diff options
Diffstat (limited to 'fs/btrfs/extent_io.c')
| -rw-r--r-- | fs/btrfs/extent_io.c | 4676 |
1 files changed, 4676 insertions, 0 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c new file mode 100644 index 0000000000..03c10e0ba0 --- /dev/null +++ b/fs/btrfs/extent_io.c @@ -0,0 +1,4676 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/bitops.h> +#include <linux/slab.h> +#include <linux/bio.h> +#include <linux/mm.h> +#include <linux/pagemap.h> +#include <linux/page-flags.h> +#include <linux/sched/mm.h> +#include <linux/spinlock.h> +#include <linux/blkdev.h> +#include <linux/swap.h> +#include <linux/writeback.h> +#include <linux/pagevec.h> +#include <linux/prefetch.h> +#include <linux/fsverity.h> +#include "misc.h" +#include "extent_io.h" +#include "extent-io-tree.h" +#include "extent_map.h" +#include "ctree.h" +#include "btrfs_inode.h" +#include "bio.h" +#include "check-integrity.h" +#include "locking.h" +#include "rcu-string.h" +#include "backref.h" +#include "disk-io.h" +#include "subpage.h" +#include "zoned.h" +#include "block-group.h" +#include "compression.h" +#include "fs.h" +#include "accessors.h" +#include "file-item.h" +#include "file.h" +#include "dev-replace.h" +#include "super.h" +#include "transaction.h" + +static struct kmem_cache *extent_buffer_cache; + +#ifdef CONFIG_BTRFS_DEBUG +static inline void btrfs_leak_debug_add_eb(struct extent_buffer *eb) +{ + struct btrfs_fs_info *fs_info = eb->fs_info; + unsigned long flags; + + spin_lock_irqsave(&fs_info->eb_leak_lock, flags); + list_add(&eb->leak_list, &fs_info->allocated_ebs); + spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags); +} + +static inline void btrfs_leak_debug_del_eb(struct extent_buffer *eb) +{ + struct btrfs_fs_info *fs_info = eb->fs_info; + unsigned long flags; + + spin_lock_irqsave(&fs_info->eb_leak_lock, flags); + list_del(&eb->leak_list); + spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags); +} + +void btrfs_extent_buffer_leak_debug_check(struct btrfs_fs_info *fs_info) +{ + struct extent_buffer *eb; + unsigned long flags; + + /* + * If we didn't get into open_ctree our allocated_ebs will not be + * initialized, so just skip this. + */ + if (!fs_info->allocated_ebs.next) + return; + + WARN_ON(!list_empty(&fs_info->allocated_ebs)); + spin_lock_irqsave(&fs_info->eb_leak_lock, flags); + while (!list_empty(&fs_info->allocated_ebs)) { + eb = list_first_entry(&fs_info->allocated_ebs, + struct extent_buffer, leak_list); + pr_err( + "BTRFS: buffer leak start %llu len %lu refs %d bflags %lu owner %llu\n", + eb->start, eb->len, atomic_read(&eb->refs), eb->bflags, + btrfs_header_owner(eb)); + list_del(&eb->leak_list); + kmem_cache_free(extent_buffer_cache, eb); + } + spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags); +} +#else +#define btrfs_leak_debug_add_eb(eb) do {} while (0) +#define btrfs_leak_debug_del_eb(eb) do {} while (0) +#endif + +/* + * Structure to record info about the bio being assembled, and other info like + * how many bytes are there before stripe/ordered extent boundary. + */ +struct btrfs_bio_ctrl { + struct btrfs_bio *bbio; + enum btrfs_compression_type compress_type; + u32 len_to_oe_boundary; + blk_opf_t opf; + btrfs_bio_end_io_t end_io_func; + struct writeback_control *wbc; +}; + +static void submit_one_bio(struct btrfs_bio_ctrl *bio_ctrl) +{ + struct btrfs_bio *bbio = bio_ctrl->bbio; + + if (!bbio) + return; + + /* Caller should ensure the bio has at least some range added */ + ASSERT(bbio->bio.bi_iter.bi_size); + + if (btrfs_op(&bbio->bio) == BTRFS_MAP_READ && + bio_ctrl->compress_type != BTRFS_COMPRESS_NONE) + btrfs_submit_compressed_read(bbio); + else + btrfs_submit_bio(bbio, 0); + + /* The bbio is owned by the end_io handler now */ + bio_ctrl->bbio = NULL; +} + +/* + * Submit or fail the current bio in the bio_ctrl structure. + */ +static void submit_write_bio(struct btrfs_bio_ctrl *bio_ctrl, int ret) +{ + struct btrfs_bio *bbio = bio_ctrl->bbio; + + if (!bbio) + return; + + if (ret) { + ASSERT(ret < 0); + btrfs_bio_end_io(bbio, errno_to_blk_status(ret)); + /* The bio is owned by the end_io handler now */ + bio_ctrl->bbio = NULL; + } else { + submit_one_bio(bio_ctrl); + } +} + +int __init extent_buffer_init_cachep(void) +{ + extent_buffer_cache = kmem_cache_create("btrfs_extent_buffer", + sizeof(struct extent_buffer), 0, + SLAB_MEM_SPREAD, NULL); + if (!extent_buffer_cache) + return -ENOMEM; + + return 0; +} + +void __cold extent_buffer_free_cachep(void) +{ + /* + * Make sure all delayed rcu free are flushed before we + * destroy caches. + */ + rcu_barrier(); + kmem_cache_destroy(extent_buffer_cache); +} + +void extent_range_clear_dirty_for_io(struct inode *inode, u64 start, u64 end) +{ + unsigned long index = start >> PAGE_SHIFT; + unsigned long end_index = end >> PAGE_SHIFT; + struct page *page; + + while (index <= end_index) { + page = find_get_page(inode->i_mapping, index); + BUG_ON(!page); /* Pages should be in the extent_io_tree */ + clear_page_dirty_for_io(page); + put_page(page); + index++; + } +} + +static void process_one_page(struct btrfs_fs_info *fs_info, + struct page *page, struct page *locked_page, + unsigned long page_ops, u64 start, u64 end) +{ + u32 len; + + ASSERT(end + 1 - start != 0 && end + 1 - start < U32_MAX); + len = end + 1 - start; + + if (page_ops & PAGE_SET_ORDERED) + btrfs_page_clamp_set_ordered(fs_info, page, start, len); + if (page_ops & PAGE_START_WRITEBACK) { + btrfs_page_clamp_clear_dirty(fs_info, page, start, len); + btrfs_page_clamp_set_writeback(fs_info, page, start, len); + } + if (page_ops & PAGE_END_WRITEBACK) + btrfs_page_clamp_clear_writeback(fs_info, page, start, len); + + if (page != locked_page && (page_ops & PAGE_UNLOCK)) + btrfs_page_end_writer_lock(fs_info, page, start, len); +} + +static void __process_pages_contig(struct address_space *mapping, + struct page *locked_page, u64 start, u64 end, + unsigned long page_ops) +{ + struct btrfs_fs_info *fs_info = btrfs_sb(mapping->host->i_sb); + pgoff_t start_index = start >> PAGE_SHIFT; + pgoff_t end_index = end >> PAGE_SHIFT; + pgoff_t index = start_index; + struct folio_batch fbatch; + int i; + + folio_batch_init(&fbatch); + while (index <= end_index) { + int found_folios; + + found_folios = filemap_get_folios_contig(mapping, &index, + end_index, &fbatch); + for (i = 0; i < found_folios; i++) { + struct folio *folio = fbatch.folios[i]; + + process_one_page(fs_info, &folio->page, locked_page, + page_ops, start, end); + } + folio_batch_release(&fbatch); + cond_resched(); + } +} + +static noinline void __unlock_for_delalloc(struct inode *inode, + struct page *locked_page, + u64 start, u64 end) +{ + unsigned long index = start >> PAGE_SHIFT; + unsigned long end_index = end >> PAGE_SHIFT; + + ASSERT(locked_page); + if (index == locked_page->index && end_index == index) + return; + + __process_pages_contig(inode->i_mapping, locked_page, start, end, + PAGE_UNLOCK); +} + +static noinline int lock_delalloc_pages(struct inode *inode, + struct page *locked_page, + u64 start, + u64 end) +{ + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); + struct address_space *mapping = inode->i_mapping; + pgoff_t start_index = start >> PAGE_SHIFT; + pgoff_t end_index = end >> PAGE_SHIFT; + pgoff_t index = start_index; + u64 processed_end = start; + struct folio_batch fbatch; + + if (index == locked_page->index && index == end_index) + return 0; + + folio_batch_init(&fbatch); + while (index <= end_index) { + unsigned int found_folios, i; + + found_folios = filemap_get_folios_contig(mapping, &index, + end_index, &fbatch); + if (found_folios == 0) + goto out; + + for (i = 0; i < found_folios; i++) { + struct page *page = &fbatch.folios[i]->page; + u32 len = end + 1 - start; + + if (page == locked_page) + continue; + + if (btrfs_page_start_writer_lock(fs_info, page, start, + len)) + goto out; + + if (!PageDirty(page) || page->mapping != mapping) { + btrfs_page_end_writer_lock(fs_info, page, start, + len); + goto out; + } + + processed_end = page_offset(page) + PAGE_SIZE - 1; + } + folio_batch_release(&fbatch); + cond_resched(); + } + + return 0; +out: + folio_batch_release(&fbatch); + if (processed_end > start) + __unlock_for_delalloc(inode, locked_page, start, processed_end); + return -EAGAIN; +} + +/* + * Find and lock a contiguous range of bytes in the file marked as delalloc, no + * more than @max_bytes. + * + * @start: The original start bytenr to search. + * Will store the extent range start bytenr. + * @end: The original end bytenr of the search range + * Will store the extent range end bytenr. + * + * Return true if we find a delalloc range which starts inside the original + * range, and @start/@end will store the delalloc range start/end. + * + * Return false if we can't find any delalloc range which starts inside the + * original range, and @start/@end will be the non-delalloc range start/end. + */ +EXPORT_FOR_TESTS +noinline_for_stack bool find_lock_delalloc_range(struct inode *inode, + struct page *locked_page, u64 *start, + u64 *end) +{ + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); + struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree; + const u64 orig_start = *start; + const u64 orig_end = *end; + /* The sanity tests may not set a valid fs_info. */ + u64 max_bytes = fs_info ? fs_info->max_extent_size : BTRFS_MAX_EXTENT_SIZE; + u64 delalloc_start; + u64 delalloc_end; + bool found; + struct extent_state *cached_state = NULL; + int ret; + int loops = 0; + + /* Caller should pass a valid @end to indicate the search range end */ + ASSERT(orig_end > orig_start); + + /* The range should at least cover part of the page */ + ASSERT(!(orig_start >= page_offset(locked_page) + PAGE_SIZE || + orig_end <= page_offset(locked_page))); +again: + /* step one, find a bunch of delalloc bytes starting at start */ + delalloc_start = *start; + delalloc_end = 0; + found = btrfs_find_delalloc_range(tree, &delalloc_start, &delalloc_end, + max_bytes, &cached_state); + if (!found || delalloc_end <= *start || delalloc_start > orig_end) { + *start = delalloc_start; + + /* @delalloc_end can be -1, never go beyond @orig_end */ + *end = min(delalloc_end, orig_end); + free_extent_state(cached_state); + return false; + } + + /* + * start comes from the offset of locked_page. We have to lock + * pages in order, so we can't process delalloc bytes before + * locked_page + */ + if (delalloc_start < *start) + delalloc_start = *start; + + /* + * make sure to limit the number of pages we try to lock down + */ + if (delalloc_end + 1 - delalloc_start > max_bytes) + delalloc_end = delalloc_start + max_bytes - 1; + + /* step two, lock all the pages after the page that has start */ + ret = lock_delalloc_pages(inode, locked_page, + delalloc_start, delalloc_end); + ASSERT(!ret || ret == -EAGAIN); + if (ret == -EAGAIN) { + /* some of the pages are gone, lets avoid looping by + * shortening the size of the delalloc range we're searching + */ + free_extent_state(cached_state); + cached_state = NULL; + if (!loops) { + max_bytes = PAGE_SIZE; + loops = 1; + goto again; + } else { + found = false; + goto out_failed; + } + } + + /* step three, lock the state bits for the whole range */ + lock_extent(tree, delalloc_start, delalloc_end, &cached_state); + + /* then test to make sure it is all still delalloc */ + ret = test_range_bit(tree, delalloc_start, delalloc_end, + EXTENT_DELALLOC, 1, cached_state); + if (!ret) { + unlock_extent(tree, delalloc_start, delalloc_end, + &cached_state); + __unlock_for_delalloc(inode, locked_page, + delalloc_start, delalloc_end); + cond_resched(); + goto again; + } + free_extent_state(cached_state); + *start = delalloc_start; + *end = delalloc_end; +out_failed: + return found; +} + +void extent_clear_unlock_delalloc(struct btrfs_inode *inode, u64 start, u64 end, + struct page *locked_page, + u32 clear_bits, unsigned long page_ops) +{ + clear_extent_bit(&inode->io_tree, start, end, clear_bits, NULL); + + __process_pages_contig(inode->vfs_inode.i_mapping, locked_page, + start, end, page_ops); +} + +static bool btrfs_verify_page(struct page *page, u64 start) +{ + if (!fsverity_active(page->mapping->host) || + PageUptodate(page) || + start >= i_size_read(page->mapping->host)) + return true; + return fsverity_verify_page(page); +} + +static void end_page_read(struct page *page, bool uptodate, u64 start, u32 len) +{ + struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb); + + ASSERT(page_offset(page) <= start && + start + len <= page_offset(page) + PAGE_SIZE); + + if (uptodate && btrfs_verify_page(page, start)) + btrfs_page_set_uptodate(fs_info, page, start, len); + else + btrfs_page_clear_uptodate(fs_info, page, start, len); + + if (!btrfs_is_subpage(fs_info, page)) + unlock_page(page); + else + btrfs_subpage_end_reader(fs_info, page, start, len); +} + +/* + * after a writepage IO is done, we need to: + * clear the uptodate bits on error + * clear the writeback bits in the extent tree for this IO + * end_page_writeback if the page has no more pending IO + * + * Scheduling is not allowed, so the extent state tree is expected + * to have one and only one object corresponding to this IO. + */ +static void end_bio_extent_writepage(struct btrfs_bio *bbio) +{ + struct bio *bio = &bbio->bio; + int error = blk_status_to_errno(bio->bi_status); + struct bio_vec *bvec; + struct bvec_iter_all iter_all; + + ASSERT(!bio_flagged(bio, BIO_CLONED)); + bio_for_each_segment_all(bvec, bio, iter_all) { + struct page *page = bvec->bv_page; + struct inode *inode = page->mapping->host; + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); + const u32 sectorsize = fs_info->sectorsize; + u64 start = page_offset(page) + bvec->bv_offset; + u32 len = bvec->bv_len; + + /* Our read/write should always be sector aligned. */ + if (!IS_ALIGNED(bvec->bv_offset, sectorsize)) + btrfs_err(fs_info, + "partial page write in btrfs with offset %u and length %u", + bvec->bv_offset, bvec->bv_len); + else if (!IS_ALIGNED(bvec->bv_len, sectorsize)) + btrfs_info(fs_info, + "incomplete page write with offset %u and length %u", + bvec->bv_offset, bvec->bv_len); + + btrfs_finish_ordered_extent(bbio->ordered, page, start, len, !error); + if (error) + mapping_set_error(page->mapping, error); + btrfs_page_clear_writeback(fs_info, page, start, len); + } + + bio_put(bio); +} + +/* + * Record previously processed extent range + * + * For endio_readpage_release_extent() to handle a full extent range, reducing + * the extent io operations. + */ +struct processed_extent { + struct btrfs_inode *inode; + /* Start of the range in @inode */ + u64 start; + /* End of the range in @inode */ + u64 end; + bool uptodate; +}; + +/* + * Try to release processed extent range + * + * May not release the extent range right now if the current range is + * contiguous to processed extent. + * + * Will release processed extent when any of @inode, @uptodate, the range is + * no longer contiguous to the processed range. + * + * Passing @inode == NULL will force processed extent to be released. + */ +static void endio_readpage_release_extent(struct processed_extent *processed, + struct btrfs_inode *inode, u64 start, u64 end, + bool uptodate) +{ + struct extent_state *cached = NULL; + struct extent_io_tree *tree; + + /* The first extent, initialize @processed */ + if (!processed->inode) + goto update; + + /* + * Contiguous to processed extent, just uptodate the end. + * + * Several things to notice: + * + * - bio can be merged as long as on-disk bytenr is contiguous + * This means we can have page belonging to other inodes, thus need to + * check if the inode still matches. + * - bvec can contain range beyond current page for multi-page bvec + * Thus we need to do processed->end + 1 >= start check + */ + if (processed->inode == inode && processed->uptodate == uptodate && + processed->end + 1 >= start && end >= processed->end) { + processed->end = end; + return; + } + + tree = &processed->inode->io_tree; + /* + * Now we don't have range contiguous to the processed range, release + * the processed range now. + */ + unlock_extent(tree, processed->start, processed->end, &cached); + +update: + /* Update processed to current range */ + processed->inode = inode; + processed->start = start; + processed->end = end; + processed->uptodate = uptodate; +} + +static void begin_page_read(struct btrfs_fs_info *fs_info, struct page *page) +{ + ASSERT(PageLocked(page)); + if (!btrfs_is_subpage(fs_info, page)) + return; + + ASSERT(PagePrivate(page)); + btrfs_subpage_start_reader(fs_info, page, page_offset(page), PAGE_SIZE); +} + +/* + * after a readpage IO is done, we need to: + * clear the uptodate bits on error + * set the uptodate bits if things worked + * set the page up to date if all extents in the tree are uptodate + * clear the lock bit in the extent tree + * unlock the page if there are no other extents locked for it + * + * Scheduling is not allowed, so the extent state tree is expected + * to have one and only one object corresponding to this IO. + */ +static void end_bio_extent_readpage(struct btrfs_bio *bbio) +{ + struct bio *bio = &bbio->bio; + struct bio_vec *bvec; + struct processed_extent processed = { 0 }; + /* + * The offset to the beginning of a bio, since one bio can never be + * larger than UINT_MAX, u32 here is enough. + */ + u32 bio_offset = 0; + struct bvec_iter_all iter_all; + + ASSERT(!bio_flagged(bio, BIO_CLONED)); + bio_for_each_segment_all(bvec, bio, iter_all) { + bool uptodate = !bio->bi_status; + struct page *page = bvec->bv_page; + struct inode *inode = page->mapping->host; + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); + const u32 sectorsize = fs_info->sectorsize; + u64 start; + u64 end; + u32 len; + + btrfs_debug(fs_info, + "end_bio_extent_readpage: bi_sector=%llu, err=%d, mirror=%u", + bio->bi_iter.bi_sector, bio->bi_status, + bbio->mirror_num); + + /* + * We always issue full-sector reads, but if some block in a + * page fails to read, blk_update_request() will advance + * bv_offset and adjust bv_len to compensate. Print a warning + * for unaligned offsets, and an error if they don't add up to + * a full sector. + */ + if (!IS_ALIGNED(bvec->bv_offset, sectorsize)) + btrfs_err(fs_info, + "partial page read in btrfs with offset %u and length %u", + bvec->bv_offset, bvec->bv_len); + else if (!IS_ALIGNED(bvec->bv_offset + bvec->bv_len, + sectorsize)) + btrfs_info(fs_info, + "incomplete page read with offset %u and length %u", + bvec->bv_offset, bvec->bv_len); + + start = page_offset(page) + bvec->bv_offset; + end = start + bvec->bv_len - 1; + len = bvec->bv_len; + + if (likely(uptodate)) { + loff_t i_size = i_size_read(inode); + pgoff_t end_index = i_size >> PAGE_SHIFT; + + /* + * Zero out the remaining part if this range straddles + * i_size. + * + * Here we should only zero the range inside the bvec, + * not touch anything else. + * + * NOTE: i_size is exclusive while end is inclusive. + */ + if (page->index == end_index && i_size <= end) { + u32 zero_start = max(offset_in_page(i_size), + offset_in_page(start)); + + zero_user_segment(page, zero_start, + offset_in_page(end) + 1); + } + } + + /* Update page status and unlock. */ + end_page_read(page, uptodate, start, len); + endio_readpage_release_extent(&processed, BTRFS_I(inode), + start, end, uptodate); + + ASSERT(bio_offset + len > bio_offset); + bio_offset += len; + + } + /* Release the last extent */ + endio_readpage_release_extent(&processed, NULL, 0, 0, false); + bio_put(bio); +} + +/* + * Populate every free slot in a provided array with pages. + * + * @nr_pages: number of pages to allocate + * @page_array: the array to fill with pages; any existing non-null entries in + * the array will be skipped + * + * Return: 0 if all pages were able to be allocated; + * -ENOMEM otherwise, the partially allocated pages would be freed and + * the array slots zeroed + */ +int btrfs_alloc_page_array(unsigned int nr_pages, struct page **page_array) +{ + unsigned int allocated; + + for (allocated = 0; allocated < nr_pages;) { + unsigned int last = allocated; + + allocated = alloc_pages_bulk_array(GFP_NOFS, nr_pages, page_array); + + if (allocated == nr_pages) + return 0; + + /* + * During this iteration, no page could be allocated, even + * though alloc_pages_bulk_array() falls back to alloc_page() + * if it could not bulk-allocate. So we must be out of memory. + */ + if (allocated == last) { + for (int i = 0; i < allocated; i++) { + __free_page(page_array[i]); + page_array[i] = NULL; + } + return -ENOMEM; + } + + memalloc_retry_wait(GFP_NOFS); + } + return 0; +} + +static bool btrfs_bio_is_contig(struct btrfs_bio_ctrl *bio_ctrl, + struct page *page, u64 disk_bytenr, + unsigned int pg_offset) +{ + struct bio *bio = &bio_ctrl->bbio->bio; + struct bio_vec *bvec = bio_last_bvec_all(bio); + const sector_t sector = disk_bytenr >> SECTOR_SHIFT; + + if (bio_ctrl->compress_type != BTRFS_COMPRESS_NONE) { + /* + * For compression, all IO should have its logical bytenr set + * to the starting bytenr of the compressed extent. + */ + return bio->bi_iter.bi_sector == sector; + } + + /* + * The contig check requires the following conditions to be met: + * + * 1) The pages are belonging to the same inode + * This is implied by the call chain. + * + * 2) The range has adjacent logical bytenr + * + * 3) The range has adjacent file offset + * This is required for the usage of btrfs_bio->file_offset. + */ + return bio_end_sector(bio) == sector && + page_offset(bvec->bv_page) + bvec->bv_offset + bvec->bv_len == + page_offset(page) + pg_offset; +} + +static void alloc_new_bio(struct btrfs_inode *inode, + struct btrfs_bio_ctrl *bio_ctrl, + u64 disk_bytenr, u64 file_offset) +{ + struct btrfs_fs_info *fs_info = inode->root->fs_info; + struct btrfs_bio *bbio; + + bbio = btrfs_bio_alloc(BIO_MAX_VECS, bio_ctrl->opf, fs_info, + bio_ctrl->end_io_func, NULL); + bbio->bio.bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT; + bbio->inode = inode; + bbio->file_offset = file_offset; + bio_ctrl->bbio = bbio; + bio_ctrl->len_to_oe_boundary = U32_MAX; + + /* Limit data write bios to the ordered boundary. */ + if (bio_ctrl->wbc) { + struct btrfs_ordered_extent *ordered; + + ordered = btrfs_lookup_ordered_extent(inode, file_offset); + if (ordered) { + bio_ctrl->len_to_oe_boundary = min_t(u32, U32_MAX, + ordered->file_offset + + ordered->disk_num_bytes - file_offset); + bbio->ordered = ordered; + } + + /* + * Pick the last added device to support cgroup writeback. For + * multi-device file systems this means blk-cgroup policies have + * to always be set on the last added/replaced device. + * This is a bit odd but has been like that for a long time. + */ + bio_set_dev(&bbio->bio, fs_info->fs_devices->latest_dev->bdev); + wbc_init_bio(bio_ctrl->wbc, &bbio->bio); + } +} + +/* + * @disk_bytenr: logical bytenr where the write will be + * @page: page to add to the bio + * @size: portion of page that we want to write to + * @pg_offset: offset of the new bio or to check whether we are adding + * a contiguous page to the previous one + * + * The will either add the page into the existing @bio_ctrl->bbio, or allocate a + * new one in @bio_ctrl->bbio. + * The mirror number for this IO should already be initizlied in + * @bio_ctrl->mirror_num. + */ +static void submit_extent_page(struct btrfs_bio_ctrl *bio_ctrl, + u64 disk_bytenr, struct page *page, + size_t size, unsigned long pg_offset) +{ + struct btrfs_inode *inode = BTRFS_I(page->mapping->host); + + ASSERT(pg_offset + size <= PAGE_SIZE); + ASSERT(bio_ctrl->end_io_func); + + if (bio_ctrl->bbio && + !btrfs_bio_is_contig(bio_ctrl, page, disk_bytenr, pg_offset)) + submit_one_bio(bio_ctrl); + + do { + u32 len = size; + + /* Allocate new bio if needed */ + if (!bio_ctrl->bbio) { + alloc_new_bio(inode, bio_ctrl, disk_bytenr, + page_offset(page) + pg_offset); + } + + /* Cap to the current ordered extent boundary if there is one. */ + if (len > bio_ctrl->len_to_oe_boundary) { + ASSERT(bio_ctrl->compress_type == BTRFS_COMPRESS_NONE); + ASSERT(is_data_inode(&inode->vfs_inode)); + len = bio_ctrl->len_to_oe_boundary; + } + + if (bio_add_page(&bio_ctrl->bbio->bio, page, len, pg_offset) != len) { + /* bio full: move on to a new one */ + submit_one_bio(bio_ctrl); + continue; + } + + if (bio_ctrl->wbc) + wbc_account_cgroup_owner(bio_ctrl->wbc, page, len); + + size -= len; + pg_offset += len; + disk_bytenr += len; + + /* + * len_to_oe_boundary defaults to U32_MAX, which isn't page or + * sector aligned. alloc_new_bio() then sets it to the end of + * our ordered extent for writes into zoned devices. + * + * When len_to_oe_boundary is tracking an ordered extent, we + * trust the ordered extent code to align things properly, and + * the check above to cap our write to the ordered extent + * boundary is correct. + * + * When len_to_oe_boundary is U32_MAX, the cap above would + * result in a 4095 byte IO for the last page right before + * we hit the bio limit of UINT_MAX. bio_add_page() has all + * the checks required to make sure we don't overflow the bio, + * and we should just ignore len_to_oe_boundary completely + * unless we're using it to track an ordered extent. + * + * It's pretty hard to make a bio sized U32_MAX, but it can + * happen when the page cache is able to feed us contiguous + * pages for large extents. + */ + if (bio_ctrl->len_to_oe_boundary != U32_MAX) + bio_ctrl->len_to_oe_boundary -= len; + + /* Ordered extent boundary: move on to a new bio. */ + if (bio_ctrl->len_to_oe_boundary == 0) + submit_one_bio(bio_ctrl); + } while (size); +} + +static int attach_extent_buffer_page(struct extent_buffer *eb, + struct page *page, + struct btrfs_subpage *prealloc) +{ + struct btrfs_fs_info *fs_info = eb->fs_info; + int ret = 0; + + /* + * If the page is mapped to btree inode, we should hold the private + * lock to prevent race. + * For cloned or dummy extent buffers, their pages are not mapped and + * will not race with any other ebs. + */ + if (page->mapping) + lockdep_assert_held(&page->mapping->private_lock); + + if (fs_info->nodesize >= PAGE_SIZE) { + if (!PagePrivate(page)) + attach_page_private(page, eb); + else + WARN_ON(page->private != (unsigned long)eb); + return 0; + } + + /* Already mapped, just free prealloc */ + if (PagePrivate(page)) { + btrfs_free_subpage(prealloc); + return 0; + } + + if (prealloc) + /* Has preallocated memory for subpage */ + attach_page_private(page, prealloc); + else + /* Do new allocation to attach subpage */ + ret = btrfs_attach_subpage(fs_info, page, + BTRFS_SUBPAGE_METADATA); + return ret; +} + +int set_page_extent_mapped(struct page *page) +{ + struct btrfs_fs_info *fs_info; + + ASSERT(page->mapping); + + if (PagePrivate(page)) + return 0; + + fs_info = btrfs_sb(page->mapping->host->i_sb); + + if (btrfs_is_subpage(fs_info, page)) + return btrfs_attach_subpage(fs_info, page, BTRFS_SUBPAGE_DATA); + + attach_page_private(page, (void *)EXTENT_PAGE_PRIVATE); + return 0; +} + +void clear_page_extent_mapped(struct page *page) +{ + struct btrfs_fs_info *fs_info; + + ASSERT(page->mapping); + + if (!PagePrivate(page)) + return; + + fs_info = btrfs_sb(page->mapping->host->i_sb); + if (btrfs_is_subpage(fs_info, page)) + return btrfs_detach_subpage(fs_info, page); + + detach_page_private(page); +} + +static struct extent_map * +__get_extent_map(struct inode *inode, struct page *page, size_t pg_offset, + u64 start, u64 len, struct extent_map **em_cached) +{ + struct extent_map *em; + + if (em_cached && *em_cached) { + em = *em_cached; + if (extent_map_in_tree(em) && start >= em->start && + start < extent_map_end(em)) { + refcount_inc(&em->refs); + return em; + } + + free_extent_map(em); + *em_cached = NULL; + } + + em = btrfs_get_extent(BTRFS_I(inode), page, pg_offset, start, len); + if (em_cached && !IS_ERR(em)) { + BUG_ON(*em_cached); + refcount_inc(&em->refs); + *em_cached = em; + } + return em; +} +/* + * basic readpage implementation. Locked extent state structs are inserted + * into the tree that are removed when the IO is done (by the end_io + * handlers) + * XXX JDM: This needs looking at to ensure proper page locking + * return 0 on success, otherwise return error + */ +static int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, + struct btrfs_bio_ctrl *bio_ctrl, u64 *prev_em_start) +{ + struct inode *inode = page->mapping->host; + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); + u64 start = page_offset(page); + const u64 end = start + PAGE_SIZE - 1; + u64 cur = start; + u64 extent_offset; + u64 last_byte = i_size_read(inode); + u64 block_start; + struct extent_map *em; + int ret = 0; + size_t pg_offset = 0; + size_t iosize; + size_t blocksize = inode->i_sb->s_blocksize; + struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree; + + ret = set_page_extent_mapped(page); + if (ret < 0) { + unlock_extent(tree, start, end, NULL); + unlock_page(page); + return ret; + } + + if (page->index == last_byte >> PAGE_SHIFT) { + size_t zero_offset = offset_in_page(last_byte); + + if (zero_offset) { + iosize = PAGE_SIZE - zero_offset; + memzero_page(page, zero_offset, iosize); + } + } + bio_ctrl->end_io_func = end_bio_extent_readpage; + begin_page_read(fs_info, page); + while (cur <= end) { + enum btrfs_compression_type compress_type = BTRFS_COMPRESS_NONE; + bool force_bio_submit = false; + u64 disk_bytenr; + + ASSERT(IS_ALIGNED(cur, fs_info->sectorsize)); + if (cur >= last_byte) { + iosize = PAGE_SIZE - pg_offset; + memzero_page(page, pg_offset, iosize); + unlock_extent(tree, cur, cur + iosize - 1, NULL); + end_page_read(page, true, cur, iosize); + break; + } + em = __get_extent_map(inode, page, pg_offset, cur, + end - cur + 1, em_cached); + if (IS_ERR(em)) { + unlock_extent(tree, cur, end, NULL); + end_page_read(page, false, cur, end + 1 - cur); + return PTR_ERR(em); + } + extent_offset = cur - em->start; + BUG_ON(extent_map_end(em) <= cur); + BUG_ON(end < cur); + + if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) + compress_type = em->compress_type; + + iosize = min(extent_map_end(em) - cur, end - cur + 1); + iosize = ALIGN(iosize, blocksize); + if (compress_type != BTRFS_COMPRESS_NONE) + disk_bytenr = em->block_start; + else + disk_bytenr = em->block_start + extent_offset; + block_start = em->block_start; + if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) + block_start = EXTENT_MAP_HOLE; + + /* + * If we have a file range that points to a compressed extent + * and it's followed by a consecutive file range that points + * to the same compressed extent (possibly with a different + * offset and/or length, so it either points to the whole extent + * or only part of it), we must make sure we do not submit a + * single bio to populate the pages for the 2 ranges because + * this makes the compressed extent read zero out the pages + * belonging to the 2nd range. Imagine the following scenario: + * + * File layout + * [0 - 8K] [8K - 24K] + * | | + * | | + * points to extent X, points to extent X, + * offset 4K, length of 8K offset 0, length 16K + * + * [extent X, compressed length = 4K uncompressed length = 16K] + * + * If the bio to read the compressed extent covers both ranges, + * it will decompress extent X into the pages belonging to the + * first range and then it will stop, zeroing out the remaining + * pages that belong to the other range that points to extent X. + * So here we make sure we submit 2 bios, one for the first + * range and another one for the third range. Both will target + * the same physical extent from disk, but we can't currently + * make the compressed bio endio callback populate the pages + * for both ranges because each compressed bio is tightly + * coupled with a single extent map, and each range can have + * an extent map with a different offset value relative to the + * uncompressed data of our extent and different lengths. This + * is a corner case so we prioritize correctness over + * non-optimal behavior (submitting 2 bios for the same extent). + */ + if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags) && + prev_em_start && *prev_em_start != (u64)-1 && + *prev_em_start != em->start) + force_bio_submit = true; + + if (prev_em_start) + *prev_em_start = em->start; + + free_extent_map(em); + em = NULL; + + /* we've found a hole, just zero and go on */ + if (block_start == EXTENT_MAP_HOLE) { + memzero_page(page, pg_offset, iosize); + + unlock_extent(tree, cur, cur + iosize - 1, NULL); + end_page_read(page, true, cur, iosize); + cur = cur + iosize; + pg_offset += iosize; + continue; + } + /* the get_extent function already copied into the page */ + if (block_start == EXTENT_MAP_INLINE) { + unlock_extent(tree, cur, cur + iosize - 1, NULL); + end_page_read(page, true, cur, iosize); + cur = cur + iosize; + pg_offset += iosize; + continue; + } + + if (bio_ctrl->compress_type != compress_type) { + submit_one_bio(bio_ctrl); + bio_ctrl->compress_type = compress_type; + } + + if (force_bio_submit) + submit_one_bio(bio_ctrl); + submit_extent_page(bio_ctrl, disk_bytenr, page, iosize, + pg_offset); + cur = cur + iosize; + pg_offset += iosize; + } + + return 0; +} + +int btrfs_read_folio(struct file *file, struct folio *folio) +{ + struct page *page = &folio->page; + struct btrfs_inode *inode = BTRFS_I(page->mapping->host); + u64 start = page_offset(page); + u64 end = start + PAGE_SIZE - 1; + struct btrfs_bio_ctrl bio_ctrl = { .opf = REQ_OP_READ }; + int ret; + + btrfs_lock_and_flush_ordered_range(inode, start, end, NULL); + + ret = btrfs_do_readpage(page, NULL, &bio_ctrl, NULL); + /* + * If btrfs_do_readpage() failed we will want to submit the assembled + * bio to do the cleanup. + */ + submit_one_bio(&bio_ctrl); + return ret; +} + +static inline void contiguous_readpages(struct page *pages[], int nr_pages, + u64 start, u64 end, + struct extent_map **em_cached, + struct btrfs_bio_ctrl *bio_ctrl, + u64 *prev_em_start) +{ + struct btrfs_inode *inode = BTRFS_I(pages[0]->mapping->host); + int index; + + btrfs_lock_and_flush_ordered_range(inode, start, end, NULL); + + for (index = 0; index < nr_pages; index++) { + btrfs_do_readpage(pages[index], em_cached, bio_ctrl, + prev_em_start); + put_page(pages[index]); + } +} + +/* + * helper for __extent_writepage, doing all of the delayed allocation setup. + * + * This returns 1 if btrfs_run_delalloc_range function did all the work required + * to write the page (copy into inline extent). In this case the IO has + * been started and the page is already unlocked. + * + * This returns 0 if all went well (page still locked) + * This returns < 0 if there were errors (page still locked) + */ +static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, + struct page *page, struct writeback_control *wbc) +{ + const u64 page_start = page_offset(page); + const u64 page_end = page_start + PAGE_SIZE - 1; + u64 delalloc_start = page_start; + u64 delalloc_end = page_end; + u64 delalloc_to_write = 0; + int ret = 0; + + while (delalloc_start < page_end) { + delalloc_end = page_end; + if (!find_lock_delalloc_range(&inode->vfs_inode, page, + &delalloc_start, &delalloc_end)) { + delalloc_start = delalloc_end + 1; + continue; + } + + ret = btrfs_run_delalloc_range(inode, page, delalloc_start, + delalloc_end, wbc); + if (ret < 0) + return ret; + + delalloc_start = delalloc_end + 1; + } + + /* + * delalloc_end is already one less than the total length, so + * we don't subtract one from PAGE_SIZE + */ + delalloc_to_write += + DIV_ROUND_UP(delalloc_end + 1 - page_start, PAGE_SIZE); + + /* + * If btrfs_run_dealloc_range() already started I/O and unlocked + * the pages, we just need to account for them here. + */ + if (ret == 1) { + wbc->nr_to_write -= delalloc_to_write; + return 1; + } + + if (wbc->nr_to_write < delalloc_to_write) { + int thresh = 8192; + + if (delalloc_to_write < thresh * 2) + thresh = delalloc_to_write; + wbc->nr_to_write = min_t(u64, delalloc_to_write, + thresh); + } + + return 0; +} + +/* + * Find the first byte we need to write. + * + * For subpage, one page can contain several sectors, and + * __extent_writepage_io() will just grab all extent maps in the page + * range and try to submit all non-inline/non-compressed extents. + * + * This is a big problem for subpage, we shouldn't re-submit already written + * data at all. + * This function will lookup subpage dirty bit to find which range we really + * need to submit. + * + * Return the next dirty range in [@start, @end). + * If no dirty range is found, @start will be page_offset(page) + PAGE_SIZE. + */ +static void find_next_dirty_byte(struct btrfs_fs_info *fs_info, + struct page *page, u64 *start, u64 *end) +{ + struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private; + struct btrfs_subpage_info *spi = fs_info->subpage_info; + u64 orig_start = *start; + /* Declare as unsigned long so we can use bitmap ops */ + unsigned long flags; + int range_start_bit; + int range_end_bit; + + /* + * For regular sector size == page size case, since one page only + * contains one sector, we return the page offset directly. + */ + if (!btrfs_is_subpage(fs_info, page)) { + *start = page_offset(page); + *end = page_offset(page) + PAGE_SIZE; + return; + } + + range_start_bit = spi->dirty_offset + + (offset_in_page(orig_start) >> fs_info->sectorsize_bits); + + /* We should have the page locked, but just in case */ + spin_lock_irqsave(&subpage->lock, flags); + bitmap_next_set_region(subpage->bitmaps, &range_start_bit, &range_end_bit, + spi->dirty_offset + spi->bitmap_nr_bits); + spin_unlock_irqrestore(&subpage->lock, flags); + + range_start_bit -= spi->dirty_offset; + range_end_bit -= spi->dirty_offset; + + *start = page_offset(page) + range_start_bit * fs_info->sectorsize; + *end = page_offset(page) + range_end_bit * fs_info->sectorsize; +} + +/* + * helper for __extent_writepage. This calls the writepage start hooks, + * and does the loop to map the page into extents and bios. + * + * We return 1 if the IO is started and the page is unlocked, + * 0 if all went well (page still locked) + * < 0 if there were errors (page still locked) + */ +static noinline_for_stack int __extent_writepage_io(struct btrfs_inode *inode, + struct page *page, + struct btrfs_bio_ctrl *bio_ctrl, + loff_t i_size, + int *nr_ret) +{ + struct btrfs_fs_info *fs_info = inode->root->fs_info; + u64 cur = page_offset(page); + u64 end = cur + PAGE_SIZE - 1; + u64 extent_offset; + u64 block_start; + struct extent_map *em; + int ret = 0; + int nr = 0; + + ret = btrfs_writepage_cow_fixup(page); + if (ret) { + /* Fixup worker will requeue */ + redirty_page_for_writepage(bio_ctrl->wbc, page); + unlock_page(page); + return 1; + } + + bio_ctrl->end_io_func = end_bio_extent_writepage; + while (cur <= end) { + u32 len = end - cur + 1; + u64 disk_bytenr; + u64 em_end; + u64 dirty_range_start = cur; + u64 dirty_range_end; + u32 iosize; + + if (cur >= i_size) { + btrfs_mark_ordered_io_finished(inode, page, cur, len, + true); + /* + * This range is beyond i_size, thus we don't need to + * bother writing back. + * But we still need to clear the dirty subpage bit, or + * the next time the page gets dirtied, we will try to + * writeback the sectors with subpage dirty bits, + * causing writeback without ordered extent. + */ + btrfs_page_clear_dirty(fs_info, page, cur, len); + break; + } + + find_next_dirty_byte(fs_info, page, &dirty_range_start, + &dirty_range_end); + if (cur < dirty_range_start) { + cur = dirty_range_start; + continue; + } + + em = btrfs_get_extent(inode, NULL, 0, cur, len); + if (IS_ERR(em)) { + ret = PTR_ERR_OR_ZERO(em); + goto out_error; + } + + extent_offset = cur - em->start; + em_end = extent_map_end(em); + ASSERT(cur <= em_end); + ASSERT(cur < end); + ASSERT(IS_ALIGNED(em->start, fs_info->sectorsize)); + ASSERT(IS_ALIGNED(em->len, fs_info->sectorsize)); + + block_start = em->block_start; + disk_bytenr = em->block_start + extent_offset; + + ASSERT(!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)); + ASSERT(block_start != EXTENT_MAP_HOLE); + ASSERT(block_start != EXTENT_MAP_INLINE); + + /* + * Note that em_end from extent_map_end() and dirty_range_end from + * find_next_dirty_byte() are all exclusive + */ + iosize = min(min(em_end, end + 1), dirty_range_end) - cur; + free_extent_map(em); + em = NULL; + + btrfs_set_range_writeback(inode, cur, cur + iosize - 1); + if (!PageWriteback(page)) { + btrfs_err(inode->root->fs_info, + "page %lu not writeback, cur %llu end %llu", + page->index, cur, end); + } + + /* + * Although the PageDirty bit is cleared before entering this + * function, subpage dirty bit is not cleared. + * So clear subpage dirty bit here so next time we won't submit + * page for range already written to disk. + */ + btrfs_page_clear_dirty(fs_info, page, cur, iosize); + + submit_extent_page(bio_ctrl, disk_bytenr, page, iosize, + cur - page_offset(page)); + cur += iosize; + nr++; + } + + btrfs_page_assert_not_dirty(fs_info, page); + *nr_ret = nr; + return 0; + +out_error: + /* + * If we finish without problem, we should not only clear page dirty, + * but also empty subpage dirty bits + */ + *nr_ret = nr; + return ret; +} + +/* + * the writepage semantics are similar to regular writepage. extent + * records are inserted to lock ranges in the tree, and as dirty areas + * are found, they are marked writeback. Then the lock bits are removed + * and the end_io handler clears the writeback ranges + * + * Return 0 if everything goes well. + * Return <0 for error. + */ +static int __extent_writepage(struct page *page, struct btrfs_bio_ctrl *bio_ctrl) +{ + struct folio *folio = page_folio(page); + struct inode *inode = page->mapping->host; + const u64 page_start = page_offset(page); + int ret; + int nr = 0; + size_t pg_offset; + loff_t i_size = i_size_read(inode); + unsigned long end_index = i_size >> PAGE_SHIFT; + + trace___extent_writepage(page, inode, bio_ctrl->wbc); + + WARN_ON(!PageLocked(page)); + + pg_offset = offset_in_page(i_size); + if (page->index > end_index || + (page->index == end_index && !pg_offset)) { + folio_invalidate(folio, 0, folio_size(folio)); + folio_unlock(folio); + return 0; + } + + if (page->index == end_index) + memzero_page(page, pg_offset, PAGE_SIZE - pg_offset); + + ret = set_page_extent_mapped(page); + if (ret < 0) + goto done; + + ret = writepage_delalloc(BTRFS_I(inode), page, bio_ctrl->wbc); + if (ret == 1) + return 0; + if (ret) + goto done; + + ret = __extent_writepage_io(BTRFS_I(inode), page, bio_ctrl, i_size, &nr); + if (ret == 1) + return 0; + + bio_ctrl->wbc->nr_to_write--; + +done: + if (nr == 0) { + /* make sure the mapping tag for page dirty gets cleared */ + set_page_writeback(page); + end_page_writeback(page); + } + if (ret) { + btrfs_mark_ordered_io_finished(BTRFS_I(inode), page, page_start, + PAGE_SIZE, !ret); + mapping_set_error(page->mapping, ret); + } + unlock_page(page); + ASSERT(ret <= 0); + return ret; +} + +void wait_on_extent_buffer_writeback(struct extent_buffer *eb) +{ + wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_WRITEBACK, + TASK_UNINTERRUPTIBLE); +} + +/* + * Lock extent buffer status and pages for writeback. + * + * Return %false if the extent buffer doesn't need to be submitted (e.g. the + * extent buffer is not dirty) + * Return %true is the extent buffer is submitted to bio. + */ +static noinline_for_stack bool lock_extent_buffer_for_io(struct extent_buffer *eb, + struct writeback_control *wbc) +{ + struct btrfs_fs_info *fs_info = eb->fs_info; + bool ret = false; + + btrfs_tree_lock(eb); + while (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)) { + btrfs_tree_unlock(eb); + if (wbc->sync_mode != WB_SYNC_ALL) + return false; + wait_on_extent_buffer_writeback(eb); + btrfs_tree_lock(eb); + } + + /* + * We need to do this to prevent races in people who check if the eb is + * under IO since we can end up having no IO bits set for a short period + * of time. + */ + spin_lock(&eb->refs_lock); + if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) { + set_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags); + spin_unlock(&eb->refs_lock); + btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN); + percpu_counter_add_batch(&fs_info->dirty_metadata_bytes, + -eb->len, + fs_info->dirty_metadata_batch); + ret = true; + } else { + spin_unlock(&eb->refs_lock); + } + btrfs_tree_unlock(eb); + return ret; +} + +static void set_btree_ioerr(struct extent_buffer *eb) +{ + struct btrfs_fs_info *fs_info = eb->fs_info; + + set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags); + + /* + * A read may stumble upon this buffer later, make sure that it gets an + * error and knows there was an error. + */ + clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); + + /* + * We need to set the mapping with the io error as well because a write + * error will flip the file system readonly, and then syncfs() will + * return a 0 because we are readonly if we don't modify the err seq for + * the superblock. + */ + mapping_set_error(eb->fs_info->btree_inode->i_mapping, -EIO); + + /* + * If writeback for a btree extent that doesn't belong to a log tree + * failed, increment the counter transaction->eb_write_errors. + * We do this because while the transaction is running and before it's + * committing (when we call filemap_fdata[write|wait]_range against + * the btree inode), we might have + * btree_inode->i_mapping->a_ops->writepages() called by the VM - if it + * returns an error or an error happens during writeback, when we're + * committing the transaction we wouldn't know about it, since the pages + * can be no longer dirty nor marked anymore for writeback (if a + * subsequent modification to the extent buffer didn't happen before the + * transaction commit), which makes filemap_fdata[write|wait]_range not + * able to find the pages tagged with SetPageError at transaction + * commit time. So if this happens we must abort the transaction, + * otherwise we commit a super block with btree roots that point to + * btree nodes/leafs whose content on disk is invalid - either garbage + * or the content of some node/leaf from a past generation that got + * cowed or deleted and is no longer valid. + * + * Note: setting AS_EIO/AS_ENOSPC in the btree inode's i_mapping would + * not be enough - we need to distinguish between log tree extents vs + * non-log tree extents, and the next filemap_fdatawait_range() call + * will catch and clear such errors in the mapping - and that call might + * be from a log sync and not from a transaction commit. Also, checking + * for the eb flag EXTENT_BUFFER_WRITE_ERR at transaction commit time is + * not done and would not be reliable - the eb might have been released + * from memory and reading it back again means that flag would not be + * set (since it's a runtime flag, not persisted on disk). + * + * Using the flags below in the btree inode also makes us achieve the + * goal of AS_EIO/AS_ENOSPC when writepages() returns success, started + * writeback for all dirty pages and before filemap_fdatawait_range() + * is called, the writeback for all dirty pages had already finished + * with errors - because we were not using AS_EIO/AS_ENOSPC, + * filemap_fdatawait_range() would return success, as it could not know + * that writeback errors happened (the pages were no longer tagged for + * writeback). + */ + switch (eb->log_index) { + case -1: + set_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags); + break; + case 0: + set_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags); + break; + case 1: + set_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags); + break; + default: + BUG(); /* unexpected, logic error */ + } +} + +/* + * The endio specific version which won't touch any unsafe spinlock in endio + * context. + */ +static struct extent_buffer *find_extent_buffer_nolock( + struct btrfs_fs_info *fs_info, u64 start) +{ + struct extent_buffer *eb; + + rcu_read_lock(); + eb = radix_tree_lookup(&fs_info->buffer_radix, + start >> fs_info->sectorsize_bits); + if (eb && atomic_inc_not_zero(&eb->refs)) { + rcu_read_unlock(); + return eb; + } + rcu_read_unlock(); + return NULL; +} + +static void extent_buffer_write_end_io(struct btrfs_bio *bbio) +{ + struct extent_buffer *eb = bbio->private; + struct btrfs_fs_info *fs_info = eb->fs_info; + bool uptodate = !bbio->bio.bi_status; + struct bvec_iter_all iter_all; + struct bio_vec *bvec; + u32 bio_offset = 0; + + if (!uptodate) + set_btree_ioerr(eb); + + bio_for_each_segment_all(bvec, &bbio->bio, iter_all) { + u64 start = eb->start + bio_offset; + struct page *page = bvec->bv_page; + u32 len = bvec->bv_len; + + btrfs_page_clear_writeback(fs_info, page, start, len); + bio_offset += len; + } + + clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags); + smp_mb__after_atomic(); + wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK); + + bio_put(&bbio->bio); +} + +static void prepare_eb_write(struct extent_buffer *eb) +{ + u32 nritems; + unsigned long start; + unsigned long end; + + clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags); + + /* Set btree blocks beyond nritems with 0 to avoid stale content */ + nritems = btrfs_header_nritems(eb); + if (btrfs_header_level(eb) > 0) { + end = btrfs_node_key_ptr_offset(eb, nritems); + memzero_extent_buffer(eb, end, eb->len - end); + } else { + /* + * Leaf: + * header 0 1 2 .. N ... data_N .. data_2 data_1 data_0 + */ + start = btrfs_item_nr_offset(eb, nritems); + end = btrfs_item_nr_offset(eb, 0); + if (nritems == 0) + end += BTRFS_LEAF_DATA_SIZE(eb->fs_info); + else + end += btrfs_item_offset(eb, nritems - 1); + memzero_extent_buffer(eb, start, end - start); + } +} + +static noinline_for_stack void write_one_eb(struct extent_buffer *eb, + struct writeback_control *wbc) +{ + struct btrfs_fs_info *fs_info = eb->fs_info; + struct btrfs_bio *bbio; + + prepare_eb_write(eb); + + bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES, + REQ_OP_WRITE | REQ_META | wbc_to_write_flags(wbc), + eb->fs_info, extent_buffer_write_end_io, eb); + bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT; + bio_set_dev(&bbio->bio, fs_info->fs_devices->latest_dev->bdev); + wbc_init_bio(wbc, &bbio->bio); + bbio->inode = BTRFS_I(eb->fs_info->btree_inode); + bbio->file_offset = eb->start; + if (fs_info->nodesize < PAGE_SIZE) { + struct page *p = eb->pages[0]; + + lock_page(p); + btrfs_subpage_set_writeback(fs_info, p, eb->start, eb->len); + if (btrfs_subpage_clear_and_test_dirty(fs_info, p, eb->start, + eb->len)) { + clear_page_dirty_for_io(p); + wbc->nr_to_write--; + } + __bio_add_page(&bbio->bio, p, eb->len, eb->start - page_offset(p)); + wbc_account_cgroup_owner(wbc, p, eb->len); + unlock_page(p); + } else { + for (int i = 0; i < num_extent_pages(eb); i++) { + struct page *p = eb->pages[i]; + + lock_page(p); + clear_page_dirty_for_io(p); + set_page_writeback(p); + __bio_add_page(&bbio->bio, p, PAGE_SIZE, 0); + wbc_account_cgroup_owner(wbc, p, PAGE_SIZE); + wbc->nr_to_write--; + unlock_page(p); + } + } + btrfs_submit_bio(bbio, 0); +} + +/* + * Submit one subpage btree page. + * + * The main difference to submit_eb_page() is: + * - Page locking + * For subpage, we don't rely on page locking at all. + * + * - Flush write bio + * We only flush bio if we may be unable to fit current extent buffers into + * current bio. + * + * Return >=0 for the number of submitted extent buffers. + * Return <0 for fatal error. + */ +static int submit_eb_subpage(struct page *page, struct writeback_control *wbc) +{ + struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb); + int submitted = 0; + u64 page_start = page_offset(page); + int bit_start = 0; + int sectors_per_node = fs_info->nodesize >> fs_info->sectorsize_bits; + + /* Lock and write each dirty extent buffers in the range */ + while (bit_start < fs_info->subpage_info->bitmap_nr_bits) { + struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private; + struct extent_buffer *eb; + unsigned long flags; + u64 start; + + /* + * Take private lock to ensure the subpage won't be detached + * in the meantime. + */ + spin_lock(&page->mapping->private_lock); + if (!PagePrivate(page)) { + spin_unlock(&page->mapping->private_lock); + break; + } + spin_lock_irqsave(&subpage->lock, flags); + if (!test_bit(bit_start + fs_info->subpage_info->dirty_offset, + subpage->bitmaps)) { + spin_unlock_irqrestore(&subpage->lock, flags); + spin_unlock(&page->mapping->private_lock); + bit_start++; + continue; + } + + start = page_start + bit_start * fs_info->sectorsize; + bit_start += sectors_per_node; + + /* + * Here we just want to grab the eb without touching extra + * spin locks, so call find_extent_buffer_nolock(). + */ + eb = find_extent_buffer_nolock(fs_info, start); + spin_unlock_irqrestore(&subpage->lock, flags); + spin_unlock(&page->mapping->private_lock); + + /* + * The eb has already reached 0 refs thus find_extent_buffer() + * doesn't return it. We don't need to write back such eb + * anyway. + */ + if (!eb) + continue; + + if (lock_extent_buffer_for_io(eb, wbc)) { + write_one_eb(eb, wbc); + submitted++; + } + free_extent_buffer(eb); + } + return submitted; +} + +/* + * Submit all page(s) of one extent buffer. + * + * @page: the page of one extent buffer + * @eb_context: to determine if we need to submit this page, if current page + * belongs to this eb, we don't need to submit + * + * The caller should pass each page in their bytenr order, and here we use + * @eb_context to determine if we have submitted pages of one extent buffer. + * + * If we have, we just skip until we hit a new page that doesn't belong to + * current @eb_context. + * + * If not, we submit all the page(s) of the extent buffer. + * + * Return >0 if we have submitted the extent buffer successfully. + * Return 0 if we don't need to submit the page, as it's already submitted by + * previous call. + * Return <0 for fatal error. + */ +static int submit_eb_page(struct page *page, struct btrfs_eb_write_context *ctx) +{ + struct writeback_control *wbc = ctx->wbc; + struct address_space *mapping = page->mapping; + struct extent_buffer *eb; + int ret; + + if (!PagePrivate(page)) + return 0; + + if (btrfs_sb(page->mapping->host->i_sb)->nodesize < PAGE_SIZE) + return submit_eb_subpage(page, wbc); + + spin_lock(&mapping->private_lock); + if (!PagePrivate(page)) { + spin_unlock(&mapping->private_lock); + return 0; + } + + eb = (struct extent_buffer *)page->private; + + /* + * Shouldn't happen and normally this would be a BUG_ON but no point + * crashing the machine for something we can survive anyway. + */ + if (WARN_ON(!eb)) { + spin_unlock(&mapping->private_lock); + return 0; + } + + if (eb == ctx->eb) { + spin_unlock(&mapping->private_lock); + return 0; + } + ret = atomic_inc_not_zero(&eb->refs); + spin_unlock(&mapping->private_lock); + if (!ret) + return 0; + + ctx->eb = eb; + + ret = btrfs_check_meta_write_pointer(eb->fs_info, ctx); + if (ret) { + if (ret == -EBUSY) + ret = 0; + free_extent_buffer(eb); + return ret; + } + + if (!lock_extent_buffer_for_io(eb, wbc)) { + free_extent_buffer(eb); + return 0; + } + /* Implies write in zoned mode. */ + if (ctx->zoned_bg) { + /* Mark the last eb in the block group. */ + btrfs_schedule_zone_finish_bg(ctx->zoned_bg, eb); + ctx->zoned_bg->meta_write_pointer += eb->len; + } + write_one_eb(eb, wbc); + free_extent_buffer(eb); + return 1; +} + +int btree_write_cache_pages(struct address_space *mapping, + struct writeback_control *wbc) +{ + struct btrfs_eb_write_context ctx = { .wbc = wbc }; + struct btrfs_fs_info *fs_info = BTRFS_I(mapping->host)->root->fs_info; + int ret = 0; + int done = 0; + int nr_to_write_done = 0; + struct folio_batch fbatch; + unsigned int nr_folios; + pgoff_t index; + pgoff_t end; /* Inclusive */ + int scanned = 0; + xa_mark_t tag; + + folio_batch_init(&fbatch); + if (wbc->range_cyclic) { + index = mapping->writeback_index; /* Start from prev offset */ + end = -1; + /* + * Start from the beginning does not need to cycle over the + * range, mark it as scanned. + */ + scanned = (index == 0); + } else { + index = wbc->range_start >> PAGE_SHIFT; + end = wbc->range_end >> PAGE_SHIFT; + scanned = 1; + } + if (wbc->sync_mode == WB_SYNC_ALL) + tag = PAGECACHE_TAG_TOWRITE; + else + tag = PAGECACHE_TAG_DIRTY; + btrfs_zoned_meta_io_lock(fs_info); +retry: + if (wbc->sync_mode == WB_SYNC_ALL) + tag_pages_for_writeback(mapping, index, end); + while (!done && !nr_to_write_done && (index <= end) && + (nr_folios = filemap_get_folios_tag(mapping, &index, end, + tag, &fbatch))) { + unsigned i; + + for (i = 0; i < nr_folios; i++) { + struct folio *folio = fbatch.folios[i]; + + ret = submit_eb_page(&folio->page, &ctx); + if (ret == 0) + continue; + if (ret < 0) { + done = 1; + break; + } + + /* + * the filesystem may choose to bump up nr_to_write. + * We have to make sure to honor the new nr_to_write + * at any time + */ + nr_to_write_done = wbc->nr_to_write <= 0; + } + folio_batch_release(&fbatch); + cond_resched(); + } + if (!scanned && !done) { + /* + * We hit the last page and there is more work to be done: wrap + * back to the start of the file + */ + scanned = 1; + index = 0; + goto retry; + } + /* + * If something went wrong, don't allow any metadata write bio to be + * submitted. + * + * This would prevent use-after-free if we had dirty pages not + * cleaned up, which can still happen by fuzzed images. + * + * - Bad extent tree + * Allowing existing tree block to be allocated for other trees. + * + * - Log tree operations + * Exiting tree blocks get allocated to log tree, bumps its + * generation, then get cleaned in tree re-balance. + * Such tree block will not be written back, since it's clean, + * thus no WRITTEN flag set. + * And after log writes back, this tree block is not traced by + * any dirty extent_io_tree. + * + * - Offending tree block gets re-dirtied from its original owner + * Since it has bumped generation, no WRITTEN flag, it can be + * reused without COWing. This tree block will not be traced + * by btrfs_transaction::dirty_pages. + * + * Now such dirty tree block will not be cleaned by any dirty + * extent io tree. Thus we don't want to submit such wild eb + * if the fs already has error. + * + * We can get ret > 0 from submit_extent_page() indicating how many ebs + * were submitted. Reset it to 0 to avoid false alerts for the caller. + */ + if (ret > 0) + ret = 0; + if (!ret && BTRFS_FS_ERROR(fs_info)) + ret = -EROFS; + + if (ctx.zoned_bg) + btrfs_put_block_group(ctx.zoned_bg); + btrfs_zoned_meta_io_unlock(fs_info); + return ret; +} + +/* + * Walk the list of dirty pages of the given address space and write all of them. + * + * @mapping: address space structure to write + * @wbc: subtract the number of written pages from *@wbc->nr_to_write + * @bio_ctrl: holds context for the write, namely the bio + * + * If a page is already under I/O, write_cache_pages() skips it, even + * if it's dirty. This is desirable behaviour for memory-cleaning writeback, + * but it is INCORRECT for data-integrity system calls such as fsync(). fsync() + * and msync() need to guarantee that all the data which was dirty at the time + * the call was made get new I/O started against them. If wbc->sync_mode is + * WB_SYNC_ALL then we were called for data integrity and we must wait for + * existing IO to complete. + */ +static int extent_write_cache_pages(struct address_space *mapping, + struct btrfs_bio_ctrl *bio_ctrl) +{ + struct writeback_control *wbc = bio_ctrl->wbc; + struct inode *inode = mapping->host; + int ret = 0; + int done = 0; + int nr_to_write_done = 0; + struct folio_batch fbatch; + unsigned int nr_folios; + pgoff_t index; + pgoff_t end; /* Inclusive */ + pgoff_t done_index; + int range_whole = 0; + int scanned = 0; + xa_mark_t tag; + + /* + * We have to hold onto the inode so that ordered extents can do their + * work when the IO finishes. The alternative to this is failing to add + * an ordered extent if the igrab() fails there and that is a huge pain + * to deal with, so instead just hold onto the inode throughout the + * writepages operation. If it fails here we are freeing up the inode + * anyway and we'd rather not waste our time writing out stuff that is + * going to be truncated anyway. + */ + if (!igrab(inode)) + return 0; + + folio_batch_init(&fbatch); + if (wbc->range_cyclic) { + index = mapping->writeback_index; /* Start from prev offset */ + end = -1; + /* + * Start from the beginning does not need to cycle over the + * range, mark it as scanned. + */ + scanned = (index == 0); + } else { + index = wbc->range_start >> PAGE_SHIFT; + end = wbc->range_end >> PAGE_SHIFT; + if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) + range_whole = 1; + scanned = 1; + } + + /* + * We do the tagged writepage as long as the snapshot flush bit is set + * and we are the first one who do the filemap_flush() on this inode. + * + * The nr_to_write == LONG_MAX is needed to make sure other flushers do + * not race in and drop the bit. + */ + if (range_whole && wbc->nr_to_write == LONG_MAX && + test_and_clear_bit(BTRFS_INODE_SNAPSHOT_FLUSH, + &BTRFS_I(inode)->runtime_flags)) + wbc->tagged_writepages = 1; + + if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) + tag = PAGECACHE_TAG_TOWRITE; + else + tag = PAGECACHE_TAG_DIRTY; +retry: + if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) + tag_pages_for_writeback(mapping, index, end); + done_index = index; + while (!done && !nr_to_write_done && (index <= end) && + (nr_folios = filemap_get_folios_tag(mapping, &index, + end, tag, &fbatch))) { + unsigned i; + + for (i = 0; i < nr_folios; i++) { + struct folio *folio = fbatch.folios[i]; + + done_index = folio_next_index(folio); + /* + * At this point we hold neither the i_pages lock nor + * the page lock: the page may be truncated or + * invalidated (changing page->mapping to NULL), + * or even swizzled back from swapper_space to + * tmpfs file mapping + */ + if (!folio_trylock(folio)) { + submit_write_bio(bio_ctrl, 0); + folio_lock(folio); + } + + if (unlikely(folio->mapping != mapping)) { + folio_unlock(folio); + continue; + } + + if (!folio_test_dirty(folio)) { + /* Someone wrote it for us. */ + folio_unlock(folio); + continue; + } + + if (wbc->sync_mode != WB_SYNC_NONE) { + if (folio_test_writeback(folio)) + submit_write_bio(bio_ctrl, 0); + folio_wait_writeback(folio); + } + + if (folio_test_writeback(folio) || + !folio_clear_dirty_for_io(folio)) { + folio_unlock(folio); + continue; + } + + ret = __extent_writepage(&folio->page, bio_ctrl); + if (ret < 0) { + done = 1; + break; + } + + /* + * The filesystem may choose to bump up nr_to_write. + * We have to make sure to honor the new nr_to_write + * at any time. + */ + nr_to_write_done = (wbc->sync_mode == WB_SYNC_NONE && + wbc->nr_to_write <= 0); + } + folio_batch_release(&fbatch); + cond_resched(); + } + if (!scanned && !done) { + /* + * We hit the last page and there is more work to be done: wrap + * back to the start of the file + */ + scanned = 1; + index = 0; + + /* + * If we're looping we could run into a page that is locked by a + * writer and that writer could be waiting on writeback for a + * page in our current bio, and thus deadlock, so flush the + * write bio here. + */ + submit_write_bio(bio_ctrl, 0); + goto retry; + } + + if (wbc->range_cyclic || (wbc->nr_to_write > 0 && range_whole)) + mapping->writeback_index = done_index; + + btrfs_add_delayed_iput(BTRFS_I(inode)); + return ret; +} + +/* + * Submit the pages in the range to bio for call sites which delalloc range has + * already been ran (aka, ordered extent inserted) and all pages are still + * locked. + */ +void extent_write_locked_range(struct inode *inode, struct page *locked_page, + u64 start, u64 end, struct writeback_control *wbc, + bool pages_dirty) +{ + bool found_error = false; + int ret = 0; + struct address_space *mapping = inode->i_mapping; + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); + const u32 sectorsize = fs_info->sectorsize; + loff_t i_size = i_size_read(inode); + u64 cur = start; + struct btrfs_bio_ctrl bio_ctrl = { + .wbc = wbc, + .opf = REQ_OP_WRITE | wbc_to_write_flags(wbc), + }; + + if (wbc->no_cgroup_owner) + bio_ctrl.opf |= REQ_BTRFS_CGROUP_PUNT; + + ASSERT(IS_ALIGNED(start, sectorsize) && IS_ALIGNED(end + 1, sectorsize)); + + while (cur <= end) { + u64 cur_end = min(round_down(cur, PAGE_SIZE) + PAGE_SIZE - 1, end); + u32 cur_len = cur_end + 1 - cur; + struct page *page; + int nr = 0; + + page = find_get_page(mapping, cur >> PAGE_SHIFT); + ASSERT(PageLocked(page)); + if (pages_dirty && page != locked_page) { + ASSERT(PageDirty(page)); + clear_page_dirty_for_io(page); + } + + ret = __extent_writepage_io(BTRFS_I(inode), page, &bio_ctrl, + i_size, &nr); + if (ret == 1) + goto next_page; + + /* Make sure the mapping tag for page dirty gets cleared. */ + if (nr == 0) { + set_page_writeback(page); + end_page_writeback(page); + } + if (ret) { + btrfs_mark_ordered_io_finished(BTRFS_I(inode), page, + cur, cur_len, !ret); + mapping_set_error(page->mapping, ret); + } + btrfs_page_unlock_writer(fs_info, page, cur, cur_len); + if (ret < 0) + found_error = true; +next_page: + put_page(page); + cur = cur_end + 1; + } + + submit_write_bio(&bio_ctrl, found_error ? ret : 0); +} + +int extent_writepages(struct address_space *mapping, + struct writeback_control *wbc) +{ + struct inode *inode = mapping->host; + int ret = 0; + struct btrfs_bio_ctrl bio_ctrl = { + .wbc = wbc, + .opf = REQ_OP_WRITE | wbc_to_write_flags(wbc), + }; + + /* + * Allow only a single thread to do the reloc work in zoned mode to + * protect the write pointer updates. + */ + btrfs_zoned_data_reloc_lock(BTRFS_I(inode)); + ret = extent_write_cache_pages(mapping, &bio_ctrl); + submit_write_bio(&bio_ctrl, ret); + btrfs_zoned_data_reloc_unlock(BTRFS_I(inode)); + return ret; +} + +void extent_readahead(struct readahead_control *rac) +{ + struct btrfs_bio_ctrl bio_ctrl = { .opf = REQ_OP_READ | REQ_RAHEAD }; + struct page *pagepool[16]; + struct extent_map *em_cached = NULL; + u64 prev_em_start = (u64)-1; + int nr; + + while ((nr = readahead_page_batch(rac, pagepool))) { + u64 contig_start = readahead_pos(rac); + u64 contig_end = contig_start + readahead_batch_length(rac) - 1; + + contiguous_readpages(pagepool, nr, contig_start, contig_end, + &em_cached, &bio_ctrl, &prev_em_start); + } + + if (em_cached) + free_extent_map(em_cached); + submit_one_bio(&bio_ctrl); +} + +/* + * basic invalidate_folio code, this waits on any locked or writeback + * ranges corresponding to the folio, and then deletes any extent state + * records from the tree + */ +int extent_invalidate_folio(struct extent_io_tree *tree, + struct folio *folio, size_t offset) +{ + struct extent_state *cached_state = NULL; + u64 start = folio_pos(folio); + u64 end = start + folio_size(folio) - 1; + size_t blocksize = folio->mapping->host->i_sb->s_blocksize; + + /* This function is only called for the btree inode */ + ASSERT(tree->owner == IO_TREE_BTREE_INODE_IO); + + start += ALIGN(offset, blocksize); + if (start > end) + return 0; + + lock_extent(tree, start, end, &cached_state); + folio_wait_writeback(folio); + + /* + * Currently for btree io tree, only EXTENT_LOCKED is utilized, + * so here we only need to unlock the extent range to free any + * existing extent state. + */ + unlock_extent(tree, start, end, &cached_state); + return 0; +} + +/* + * a helper for release_folio, this tests for areas of the page that + * are locked or under IO and drops the related state bits if it is safe + * to drop the page. + */ +static int try_release_extent_state(struct extent_io_tree *tree, + struct page *page, gfp_t mask) +{ + u64 start = page_offset(page); + u64 end = start + PAGE_SIZE - 1; + int ret = 1; + + if (test_range_bit(tree, start, end, EXTENT_LOCKED, 0, NULL)) { + ret = 0; + } else { + u32 clear_bits = ~(EXTENT_LOCKED | EXTENT_NODATASUM | + EXTENT_DELALLOC_NEW | EXTENT_CTLBITS | + EXTENT_QGROUP_RESERVED); + + /* + * At this point we can safely clear everything except the + * locked bit, the nodatasum bit and the delalloc new bit. + * The delalloc new bit will be cleared by ordered extent + * completion. + */ + ret = __clear_extent_bit(tree, start, end, clear_bits, NULL, NULL); + + /* if clear_extent_bit failed for enomem reasons, + * we can't allow the release to continue. + */ + if (ret < 0) + ret = 0; + else + ret = 1; + } + return ret; +} + +/* + * a helper for release_folio. As long as there are no locked extents + * in the range corresponding to the page, both state records and extent + * map records are removed + */ +int try_release_extent_mapping(struct page *page, gfp_t mask) +{ + struct extent_map *em; + u64 start = page_offset(page); + u64 end = start + PAGE_SIZE - 1; + struct btrfs_inode *btrfs_inode = BTRFS_I(page->mapping->host); + struct extent_io_tree *tree = &btrfs_inode->io_tree; + struct extent_map_tree *map = &btrfs_inode->extent_tree; + + if (gfpflags_allow_blocking(mask) && + page->mapping->host->i_size > SZ_16M) { + u64 len; + while (start <= end) { + struct btrfs_fs_info *fs_info; + u64 cur_gen; + + len = end - start + 1; + write_lock(&map->lock); + em = lookup_extent_mapping(map, start, len); + if (!em) { + write_unlock(&map->lock); + break; + } + if (test_bit(EXTENT_FLAG_PINNED, &em->flags) || + em->start != start) { + write_unlock(&map->lock); + free_extent_map(em); + break; + } + if (test_range_bit(tree, em->start, + extent_map_end(em) - 1, + EXTENT_LOCKED, 0, NULL)) + goto next; + /* + * If it's not in the list of modified extents, used + * by a fast fsync, we can remove it. If it's being + * logged we can safely remove it since fsync took an + * extra reference on the em. + */ + if (list_empty(&em->list) || + test_bit(EXTENT_FLAG_LOGGING, &em->flags)) + goto remove_em; + /* + * If it's in the list of modified extents, remove it + * only if its generation is older then the current one, + * in which case we don't need it for a fast fsync. + * Otherwise don't remove it, we could be racing with an + * ongoing fast fsync that could miss the new extent. + */ + fs_info = btrfs_inode->root->fs_info; + spin_lock(&fs_info->trans_lock); + cur_gen = fs_info->generation; + spin_unlock(&fs_info->trans_lock); + if (em->generation >= cur_gen) + goto next; +remove_em: + /* + * We only remove extent maps that are not in the list of + * modified extents or that are in the list but with a + * generation lower then the current generation, so there + * is no need to set the full fsync flag on the inode (it + * hurts the fsync performance for workloads with a data + * size that exceeds or is close to the system's memory). + */ + remove_extent_mapping(map, em); + /* once for the rb tree */ + free_extent_map(em); +next: + start = extent_map_end(em); + write_unlock(&map->lock); + + /* once for us */ + free_extent_map(em); + + cond_resched(); /* Allow large-extent preemption. */ + } + } + return try_release_extent_state(tree, page, mask); +} + +/* + * To cache previous fiemap extent + * + * Will be used for merging fiemap extent + */ +struct fiemap_cache { + u64 offset; + u64 phys; + u64 len; + u32 flags; + bool cached; +}; + +/* + * Helper to submit fiemap extent. + * + * Will try to merge current fiemap extent specified by @offset, @phys, + * @len and @flags with cached one. + * And only when we fails to merge, cached one will be submitted as + * fiemap extent. + * + * Return value is the same as fiemap_fill_next_extent(). + */ +static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo, + struct fiemap_cache *cache, + u64 offset, u64 phys, u64 len, u32 flags) +{ + int ret = 0; + + /* Set at the end of extent_fiemap(). */ + ASSERT((flags & FIEMAP_EXTENT_LAST) == 0); + + if (!cache->cached) + goto assign; + + /* + * Sanity check, extent_fiemap() should have ensured that new + * fiemap extent won't overlap with cached one. + * Not recoverable. + * + * NOTE: Physical address can overlap, due to compression + */ + if (cache->offset + cache->len > offset) { + WARN_ON(1); + return -EINVAL; + } + + /* + * Only merges fiemap extents if + * 1) Their logical addresses are continuous + * + * 2) Their physical addresses are continuous + * So truly compressed (physical size smaller than logical size) + * extents won't get merged with each other + * + * 3) Share same flags + */ + if (cache->offset + cache->len == offset && + cache->phys + cache->len == phys && + cache->flags == flags) { + cache->len += len; + return 0; + } + + /* Not mergeable, need to submit cached one */ + ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys, + cache->len, cache->flags); + cache->cached = false; + if (ret) + return ret; +assign: + cache->cached = true; + cache->offset = offset; + cache->phys = phys; + cache->len = len; + cache->flags = flags; + + return 0; +} + +/* + * Emit last fiemap cache + * + * The last fiemap cache may still be cached in the following case: + * 0 4k 8k + * |<- Fiemap range ->| + * |<------------ First extent ----------->| + * + * In this case, the first extent range will be cached but not emitted. + * So we must emit it before ending extent_fiemap(). + */ +static int emit_last_fiemap_cache(struct fiemap_extent_info *fieinfo, + struct fiemap_cache *cache) +{ + int ret; + + if (!cache->cached) + return 0; + + ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys, + cache->len, cache->flags); + cache->cached = false; + if (ret > 0) + ret = 0; + return ret; +} + +static int fiemap_next_leaf_item(struct btrfs_inode *inode, struct btrfs_path *path) +{ + struct extent_buffer *clone; + struct btrfs_key key; + int slot; + int ret; + + path->slots[0]++; + if (path->slots[0] < btrfs_header_nritems(path->nodes[0])) + return 0; + + ret = btrfs_next_leaf(inode->root, path); + if (ret != 0) + return ret; + + /* + * Don't bother with cloning if there are no more file extent items for + * our inode. + */ + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); + if (key.objectid != btrfs_ino(inode) || key.type != BTRFS_EXTENT_DATA_KEY) + return 1; + + /* See the comment at fiemap_search_slot() about why we clone. */ + clone = btrfs_clone_extent_buffer(path->nodes[0]); + if (!clone) + return -ENOMEM; + + slot = path->slots[0]; + btrfs_release_path(path); + path->nodes[0] = clone; + path->slots[0] = slot; + + return 0; +} + +/* + * Search for the first file extent item that starts at a given file offset or + * the one that starts immediately before that offset. + * Returns: 0 on success, < 0 on error, 1 if not found. + */ +static int fiemap_search_slot(struct btrfs_inode *inode, struct btrfs_path *path, + u64 file_offset) +{ + const u64 ino = btrfs_ino(inode); + struct btrfs_root *root = inode->root; + struct extent_buffer *clone; + struct btrfs_key key; + int slot; + int ret; + + key.objectid = ino; + key.type = BTRFS_EXTENT_DATA_KEY; + key.offset = file_offset; + + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + if (ret < 0) + return ret; + + if (ret > 0 && path->slots[0] > 0) { + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0] - 1); + if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY) + path->slots[0]--; + } + + if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) { + ret = btrfs_next_leaf(root, path); + if (ret != 0) + return ret; + + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); + if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY) + return 1; + } + + /* + * We clone the leaf and use it during fiemap. This is because while + * using the leaf we do expensive things like checking if an extent is + * shared, which can take a long time. In order to prevent blocking + * other tasks for too long, we use a clone of the leaf. We have locked + * the file range in the inode's io tree, so we know none of our file + * extent items can change. This way we avoid blocking other tasks that + * want to insert items for other inodes in the same leaf or b+tree + * rebalance operations (triggered for example when someone is trying + * to push items into this leaf when trying to insert an item in a + * neighbour leaf). + * We also need the private clone because holding a read lock on an + * extent buffer of the subvolume's b+tree will make lockdep unhappy + * when we call fiemap_fill_next_extent(), because that may cause a page + * fault when filling the user space buffer with fiemap data. + */ + clone = btrfs_clone_extent_buffer(path->nodes[0]); + if (!clone) + return -ENOMEM; + + slot = path->slots[0]; + btrfs_release_path(path); + path->nodes[0] = clone; + path->slots[0] = slot; + + return 0; +} + +/* + * Process a range which is a hole or a prealloc extent in the inode's subvolume + * btree. If @disk_bytenr is 0, we are dealing with a hole, otherwise a prealloc + * extent. The end offset (@end) is inclusive. + */ +static int fiemap_process_hole(struct btrfs_inode *inode, + struct fiemap_extent_info *fieinfo, + struct fiemap_cache *cache, + struct extent_state **delalloc_cached_state, + struct btrfs_backref_share_check_ctx *backref_ctx, + u64 disk_bytenr, u64 extent_offset, + u64 extent_gen, + u64 start, u64 end) +{ + const u64 i_size = i_size_read(&inode->vfs_inode); + u64 cur_offset = start; + u64 last_delalloc_end = 0; + u32 prealloc_flags = FIEMAP_EXTENT_UNWRITTEN; + bool checked_extent_shared = false; + int ret; + + /* + * There can be no delalloc past i_size, so don't waste time looking for + * it beyond i_size. + */ + while (cur_offset < end && cur_offset < i_size) { + u64 delalloc_start; + u64 delalloc_end; + u64 prealloc_start; + u64 prealloc_len = 0; + bool delalloc; + + delalloc = btrfs_find_delalloc_in_range(inode, cur_offset, end, + delalloc_cached_state, + &delalloc_start, + &delalloc_end); + if (!delalloc) + break; + + /* + * If this is a prealloc extent we have to report every section + * of it that has no delalloc. + */ + if (disk_bytenr != 0) { + if (last_delalloc_end == 0) { + prealloc_start = start; + prealloc_len = delalloc_start - start; + } else { + prealloc_start = last_delalloc_end + 1; + prealloc_len = delalloc_start - prealloc_start; + } + } + + if (prealloc_len > 0) { + if (!checked_extent_shared && fieinfo->fi_extents_max) { + ret = btrfs_is_data_extent_shared(inode, + disk_bytenr, + extent_gen, + backref_ctx); + if (ret < 0) + return ret; + else if (ret > 0) + prealloc_flags |= FIEMAP_EXTENT_SHARED; + + checked_extent_shared = true; + } + ret = emit_fiemap_extent(fieinfo, cache, prealloc_start, + disk_bytenr + extent_offset, + prealloc_len, prealloc_flags); + if (ret) + return ret; + extent_offset += prealloc_len; + } + + ret = emit_fiemap_extent(fieinfo, cache, delalloc_start, 0, + delalloc_end + 1 - delalloc_start, + FIEMAP_EXTENT_DELALLOC | + FIEMAP_EXTENT_UNKNOWN); + if (ret) + return ret; + + last_delalloc_end = delalloc_end; + cur_offset = delalloc_end + 1; + extent_offset += cur_offset - delalloc_start; + cond_resched(); + } + + /* + * Either we found no delalloc for the whole prealloc extent or we have + * a prealloc extent that spans i_size or starts at or after i_size. + */ + if (disk_bytenr != 0 && last_delalloc_end < end) { + u64 prealloc_start; + u64 prealloc_len; + + if (last_delalloc_end == 0) { + prealloc_start = start; + prealloc_len = end + 1 - start; + } else { + prealloc_start = last_delalloc_end + 1; + prealloc_len = end + 1 - prealloc_start; + } + + if (!checked_extent_shared && fieinfo->fi_extents_max) { + ret = btrfs_is_data_extent_shared(inode, + disk_bytenr, + extent_gen, + backref_ctx); + if (ret < 0) + return ret; + else if (ret > 0) + prealloc_flags |= FIEMAP_EXTENT_SHARED; + } + ret = emit_fiemap_extent(fieinfo, cache, prealloc_start, + disk_bytenr + extent_offset, + prealloc_len, prealloc_flags); + if (ret) + return ret; + } + + return 0; +} + +static int fiemap_find_last_extent_offset(struct btrfs_inode *inode, + struct btrfs_path *path, + u64 *last_extent_end_ret) +{ + const u64 ino = btrfs_ino(inode); + struct btrfs_root *root = inode->root; + struct extent_buffer *leaf; + struct btrfs_file_extent_item *ei; + struct btrfs_key key; + u64 disk_bytenr; + int ret; + + /* + * Lookup the last file extent. We're not using i_size here because + * there might be preallocation past i_size. + */ + ret = btrfs_lookup_file_extent(NULL, root, path, ino, (u64)-1, 0); + /* There can't be a file extent item at offset (u64)-1 */ + ASSERT(ret != 0); + if (ret < 0) + return ret; + + /* + * For a non-existing key, btrfs_search_slot() always leaves us at a + * slot > 0, except if the btree is empty, which is impossible because + * at least it has the inode item for this inode and all the items for + * the root inode 256. + */ + ASSERT(path->slots[0] > 0); + path->slots[0]--; + leaf = path->nodes[0]; + btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); + if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY) { + /* No file extent items in the subvolume tree. */ + *last_extent_end_ret = 0; + return 0; + } + + /* + * For an inline extent, the disk_bytenr is where inline data starts at, + * so first check if we have an inline extent item before checking if we + * have an implicit hole (disk_bytenr == 0). + */ + ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); + if (btrfs_file_extent_type(leaf, ei) == BTRFS_FILE_EXTENT_INLINE) { + *last_extent_end_ret = btrfs_file_extent_end(path); + return 0; + } + + /* + * Find the last file extent item that is not a hole (when NO_HOLES is + * not enabled). This should take at most 2 iterations in the worst + * case: we have one hole file extent item at slot 0 of a leaf and + * another hole file extent item as the last item in the previous leaf. + * This is because we merge file extent items that represent holes. + */ + disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei); + while (disk_bytenr == 0) { + ret = btrfs_previous_item(root, path, ino, BTRFS_EXTENT_DATA_KEY); + if (ret < 0) { + return ret; + } else if (ret > 0) { + /* No file extent items that are not holes. */ + *last_extent_end_ret = 0; + return 0; + } + leaf = path->nodes[0]; + ei = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_file_extent_item); + disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei); + } + + *last_extent_end_ret = btrfs_file_extent_end(path); + return 0; +} + +int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo, + u64 start, u64 len) +{ + const u64 ino = btrfs_ino(inode); + struct extent_state *cached_state = NULL; + struct extent_state *delalloc_cached_state = NULL; + struct btrfs_path *path; + struct fiemap_cache cache = { 0 }; + struct btrfs_backref_share_check_ctx *backref_ctx; + u64 last_extent_end; + u64 prev_extent_end; + u64 lockstart; + u64 lockend; + bool stopped = false; + int ret; + + backref_ctx = btrfs_alloc_backref_share_check_ctx(); + path = btrfs_alloc_path(); + if (!backref_ctx || !path) { + ret = -ENOMEM; + goto out; + } + + lockstart = round_down(start, inode->root->fs_info->sectorsize); + lockend = round_up(start + len, inode->root->fs_info->sectorsize); + prev_extent_end = lockstart; + + btrfs_inode_lock(inode, BTRFS_ILOCK_SHARED); + lock_extent(&inode->io_tree, lockstart, lockend, &cached_state); + + ret = fiemap_find_last_extent_offset(inode, path, &last_extent_end); + if (ret < 0) + goto out_unlock; + btrfs_release_path(path); + + path->reada = READA_FORWARD; + ret = fiemap_search_slot(inode, path, lockstart); + if (ret < 0) { + goto out_unlock; + } else if (ret > 0) { + /* + * No file extent item found, but we may have delalloc between + * the current offset and i_size. So check for that. + */ + ret = 0; + goto check_eof_delalloc; + } + + while (prev_extent_end < lockend) { + struct extent_buffer *leaf = path->nodes[0]; + struct btrfs_file_extent_item *ei; + struct btrfs_key key; + u64 extent_end; + u64 extent_len; + u64 extent_offset = 0; + u64 extent_gen; + u64 disk_bytenr = 0; + u64 flags = 0; + int extent_type; + u8 compression; + + btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); + if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY) + break; + + extent_end = btrfs_file_extent_end(path); + + /* + * The first iteration can leave us at an extent item that ends + * before our range's start. Move to the next item. + */ + if (extent_end <= lockstart) + goto next_item; + + backref_ctx->curr_leaf_bytenr = leaf->start; + + /* We have in implicit hole (NO_HOLES feature enabled). */ + if (prev_extent_end < key.offset) { + const u64 range_end = min(key.offset, lockend) - 1; + + ret = fiemap_process_hole(inode, fieinfo, &cache, + &delalloc_cached_state, + backref_ctx, 0, 0, 0, + prev_extent_end, range_end); + if (ret < 0) { + goto out_unlock; + } else if (ret > 0) { + /* fiemap_fill_next_extent() told us to stop. */ + stopped = true; + break; + } + + /* We've reached the end of the fiemap range, stop. */ + if (key.offset >= lockend) { + stopped = true; + break; + } + } + + extent_len = extent_end - key.offset; + ei = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_file_extent_item); + compression = btrfs_file_extent_compression(leaf, ei); + extent_type = btrfs_file_extent_type(leaf, ei); + extent_gen = btrfs_file_extent_generation(leaf, ei); + + if (extent_type != BTRFS_FILE_EXTENT_INLINE) { + disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei); + if (compression == BTRFS_COMPRESS_NONE) + extent_offset = btrfs_file_extent_offset(leaf, ei); + } + + if (compression != BTRFS_COMPRESS_NONE) + flags |= FIEMAP_EXTENT_ENCODED; + + if (extent_type == BTRFS_FILE_EXTENT_INLINE) { + flags |= FIEMAP_EXTENT_DATA_INLINE; + flags |= FIEMAP_EXTENT_NOT_ALIGNED; + ret = emit_fiemap_extent(fieinfo, &cache, key.offset, 0, + extent_len, flags); + } else if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) { + ret = fiemap_process_hole(inode, fieinfo, &cache, + &delalloc_cached_state, + backref_ctx, + disk_bytenr, extent_offset, + extent_gen, key.offset, + extent_end - 1); + } else if (disk_bytenr == 0) { + /* We have an explicit hole. */ + ret = fiemap_process_hole(inode, fieinfo, &cache, + &delalloc_cached_state, + backref_ctx, 0, 0, 0, + key.offset, extent_end - 1); + } else { + /* We have a regular extent. */ + if (fieinfo->fi_extents_max) { + ret = btrfs_is_data_extent_shared(inode, + disk_bytenr, + extent_gen, + backref_ctx); + if (ret < 0) + goto out_unlock; + else if (ret > 0) + flags |= FIEMAP_EXTENT_SHARED; + } + + ret = emit_fiemap_extent(fieinfo, &cache, key.offset, + disk_bytenr + extent_offset, + extent_len, flags); + } + + if (ret < 0) { + goto out_unlock; + } else if (ret > 0) { + /* fiemap_fill_next_extent() told us to stop. */ + stopped = true; + break; + } + + prev_extent_end = extent_end; +next_item: + if (fatal_signal_pending(current)) { + ret = -EINTR; + goto out_unlock; + } + + ret = fiemap_next_leaf_item(inode, path); + if (ret < 0) { + goto out_unlock; + } else if (ret > 0) { + /* No more file extent items for this inode. */ + break; + } + cond_resched(); + } + +check_eof_delalloc: + /* + * Release (and free) the path before emitting any final entries to + * fiemap_fill_next_extent() to keep lockdep happy. This is because + * once we find no more file extent items exist, we may have a + * non-cloned leaf, and fiemap_fill_next_extent() can trigger page + * faults when copying data to the user space buffer. + */ + btrfs_free_path(path); + path = NULL; + + if (!stopped && prev_extent_end < lockend) { + ret = fiemap_process_hole(inode, fieinfo, &cache, + &delalloc_cached_state, backref_ctx, + 0, 0, 0, prev_extent_end, lockend - 1); + if (ret < 0) + goto out_unlock; + prev_extent_end = lockend; + } + + if (cache.cached && cache.offset + cache.len >= last_extent_end) { + const u64 i_size = i_size_read(&inode->vfs_inode); + + if (prev_extent_end < i_size) { + u64 delalloc_start; + u64 delalloc_end; + bool delalloc; + + delalloc = btrfs_find_delalloc_in_range(inode, + prev_extent_end, + i_size - 1, + &delalloc_cached_state, + &delalloc_start, + &delalloc_end); + if (!delalloc) + cache.flags |= FIEMAP_EXTENT_LAST; + } else { + cache.flags |= FIEMAP_EXTENT_LAST; + } + } + + ret = emit_last_fiemap_cache(fieinfo, &cache); + +out_unlock: + unlock_extent(&inode->io_tree, lockstart, lockend, &cached_state); + btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED); +out: + free_extent_state(delalloc_cached_state); + btrfs_free_backref_share_ctx(backref_ctx); + btrfs_free_path(path); + return ret; +} + +static void __free_extent_buffer(struct extent_buffer *eb) +{ + kmem_cache_free(extent_buffer_cache, eb); +} + +static int extent_buffer_under_io(const struct extent_buffer *eb) +{ + return (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) || + test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)); +} + +static bool page_range_has_eb(struct btrfs_fs_info *fs_info, struct page *page) +{ + struct btrfs_subpage *subpage; + + lockdep_assert_held(&page->mapping->private_lock); + + if (PagePrivate(page)) { + subpage = (struct btrfs_subpage *)page->private; + if (atomic_read(&subpage->eb_refs)) + return true; + /* + * Even there is no eb refs here, we may still have + * end_page_read() call relying on page::private. + */ + if (atomic_read(&subpage->readers)) + return true; + } + return false; +} + +static void detach_extent_buffer_page(struct extent_buffer *eb, struct page *page) +{ + struct btrfs_fs_info *fs_info = eb->fs_info; + const bool mapped = !test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags); + + /* + * For mapped eb, we're going to change the page private, which should + * be done under the private_lock. + */ + if (mapped) + spin_lock(&page->mapping->private_lock); + + if (!PagePrivate(page)) { + if (mapped) + spin_unlock(&page->mapping->private_lock); + return; + } + + if (fs_info->nodesize >= PAGE_SIZE) { + /* + * We do this since we'll remove the pages after we've + * removed the eb from the radix tree, so we could race + * and have this page now attached to the new eb. So + * only clear page_private if it's still connected to + * this eb. + */ + if (PagePrivate(page) && + page->private == (unsigned long)eb) { + BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)); + BUG_ON(PageDirty(page)); + BUG_ON(PageWriteback(page)); + /* + * We need to make sure we haven't be attached + * to a new eb. + */ + detach_page_private(page); + } + if (mapped) + spin_unlock(&page->mapping->private_lock); + return; + } + + /* + * For subpage, we can have dummy eb with page private. In this case, + * we can directly detach the private as such page is only attached to + * one dummy eb, no sharing. + */ + if (!mapped) { + btrfs_detach_subpage(fs_info, page); + return; + } + + btrfs_page_dec_eb_refs(fs_info, page); + + /* + * We can only detach the page private if there are no other ebs in the + * page range and no unfinished IO. + */ + if (!page_range_has_eb(fs_info, page)) + btrfs_detach_subpage(fs_info, page); + + spin_unlock(&page->mapping->private_lock); +} + +/* Release all pages attached to the extent buffer */ +static void btrfs_release_extent_buffer_pages(struct extent_buffer *eb) +{ + int i; + int num_pages; + + ASSERT(!extent_buffer_under_io(eb)); + + num_pages = num_extent_pages(eb); + for (i = 0; i < num_pages; i++) { + struct page *page = eb->pages[i]; + + if (!page) + continue; + + detach_extent_buffer_page(eb, page); + + /* One for when we allocated the page */ + put_page(page); + } +} + +/* + * Helper for releasing the extent buffer. + */ +static inline void btrfs_release_extent_buffer(struct extent_buffer *eb) +{ + btrfs_release_extent_buffer_pages(eb); + btrfs_leak_debug_del_eb(eb); + __free_extent_buffer(eb); +} + +static struct extent_buffer * +__alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start, + unsigned long len) +{ + struct extent_buffer *eb = NULL; + + eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|__GFP_NOFAIL); + eb->start = start; + eb->len = len; + eb->fs_info = fs_info; + init_rwsem(&eb->lock); + + btrfs_leak_debug_add_eb(eb); + + spin_lock_init(&eb->refs_lock); + atomic_set(&eb->refs, 1); + + ASSERT(len <= BTRFS_MAX_METADATA_BLOCKSIZE); + + return eb; +} + +struct extent_buffer *btrfs_clone_extent_buffer(const struct extent_buffer *src) +{ + int i; + struct extent_buffer *new; + int num_pages = num_extent_pages(src); + int ret; + + new = __alloc_extent_buffer(src->fs_info, src->start, src->len); + if (new == NULL) + return NULL; + + /* + * Set UNMAPPED before calling btrfs_release_extent_buffer(), as + * btrfs_release_extent_buffer() have different behavior for + * UNMAPPED subpage extent buffer. + */ + set_bit(EXTENT_BUFFER_UNMAPPED, &new->bflags); + + ret = btrfs_alloc_page_array(num_pages, new->pages); + if (ret) { + btrfs_release_extent_buffer(new); + return NULL; + } + + for (i = 0; i < num_pages; i++) { + int ret; + struct page *p = new->pages[i]; + + ret = attach_extent_buffer_page(new, p, NULL); + if (ret < 0) { + btrfs_release_extent_buffer(new); + return NULL; + } + WARN_ON(PageDirty(p)); + } + copy_extent_buffer_full(new, src); + set_extent_buffer_uptodate(new); + + return new; +} + +struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info, + u64 start, unsigned long len) +{ + struct extent_buffer *eb; + int num_pages; + int i; + int ret; + + eb = __alloc_extent_buffer(fs_info, start, len); + if (!eb) + return NULL; + + num_pages = num_extent_pages(eb); + ret = btrfs_alloc_page_array(num_pages, eb->pages); + if (ret) + goto err; + + for (i = 0; i < num_pages; i++) { + struct page *p = eb->pages[i]; + + ret = attach_extent_buffer_page(eb, p, NULL); + if (ret < 0) + goto err; + } + + set_extent_buffer_uptodate(eb); + btrfs_set_header_nritems(eb, 0); + set_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags); + + return eb; +err: + for (i = 0; i < num_pages; i++) { + if (eb->pages[i]) { + detach_extent_buffer_page(eb, eb->pages[i]); + __free_page(eb->pages[i]); + } + } + __free_extent_buffer(eb); + return NULL; +} + +struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info, + u64 start) +{ + return __alloc_dummy_extent_buffer(fs_info, start, fs_info->nodesize); +} + +static void check_buffer_tree_ref(struct extent_buffer *eb) +{ + int refs; + /* + * The TREE_REF bit is first set when the extent_buffer is added + * to the radix tree. It is also reset, if unset, when a new reference + * is created by find_extent_buffer. + * + * It is only cleared in two cases: freeing the last non-tree + * reference to the extent_buffer when its STALE bit is set or + * calling release_folio when the tree reference is the only reference. + * + * In both cases, care is taken to ensure that the extent_buffer's + * pages are not under io. However, release_folio can be concurrently + * called with creating new references, which is prone to race + * conditions between the calls to check_buffer_tree_ref in those + * codepaths and clearing TREE_REF in try_release_extent_buffer. + * + * The actual lifetime of the extent_buffer in the radix tree is + * adequately protected by the refcount, but the TREE_REF bit and + * its corresponding reference are not. To protect against this + * class of races, we call check_buffer_tree_ref from the codepaths + * which trigger io. Note that once io is initiated, TREE_REF can no + * longer be cleared, so that is the moment at which any such race is + * best fixed. + */ + refs = atomic_read(&eb->refs); + if (refs >= 2 && test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) + return; + + spin_lock(&eb->refs_lock); + if (!test_and_set_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) + atomic_inc(&eb->refs); + spin_unlock(&eb->refs_lock); +} + +static void mark_extent_buffer_accessed(struct extent_buffer *eb, + struct page *accessed) +{ + int num_pages, i; + + check_buffer_tree_ref(eb); + + num_pages = num_extent_pages(eb); + for (i = 0; i < num_pages; i++) { + struct page *p = eb->pages[i]; + + if (p != accessed) + mark_page_accessed(p); + } +} + +struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info, + u64 start) +{ + struct extent_buffer *eb; + + eb = find_extent_buffer_nolock(fs_info, start); + if (!eb) + return NULL; + /* + * Lock our eb's refs_lock to avoid races with free_extent_buffer(). + * When we get our eb it might be flagged with EXTENT_BUFFER_STALE and + * another task running free_extent_buffer() might have seen that flag + * set, eb->refs == 2, that the buffer isn't under IO (dirty and + * writeback flags not set) and it's still in the tree (flag + * EXTENT_BUFFER_TREE_REF set), therefore being in the process of + * decrementing the extent buffer's reference count twice. So here we + * could race and increment the eb's reference count, clear its stale + * flag, mark it as dirty and drop our reference before the other task + * finishes executing free_extent_buffer, which would later result in + * an attempt to free an extent buffer that is dirty. + */ + if (test_bit(EXTENT_BUFFER_STALE, &eb->bflags)) { + spin_lock(&eb->refs_lock); + spin_unlock(&eb->refs_lock); + } + mark_extent_buffer_accessed(eb, NULL); + return eb; +} + +#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS +struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info, + u64 start) +{ + struct extent_buffer *eb, *exists = NULL; + int ret; + + eb = find_extent_buffer(fs_info, start); + if (eb) + return eb; + eb = alloc_dummy_extent_buffer(fs_info, start); + if (!eb) + return ERR_PTR(-ENOMEM); + eb->fs_info = fs_info; +again: + ret = radix_tree_preload(GFP_NOFS); + if (ret) { + exists = ERR_PTR(ret); + goto free_eb; + } + spin_lock(&fs_info->buffer_lock); + ret = radix_tree_insert(&fs_info->buffer_radix, + start >> fs_info->sectorsize_bits, eb); + spin_unlock(&fs_info->buffer_lock); + radix_tree_preload_end(); + if (ret == -EEXIST) { + exists = find_extent_buffer(fs_info, start); + if (exists) + goto free_eb; + else + goto again; + } + check_buffer_tree_ref(eb); + set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags); + + return eb; +free_eb: + btrfs_release_extent_buffer(eb); + return exists; +} +#endif + +static struct extent_buffer *grab_extent_buffer( + struct btrfs_fs_info *fs_info, struct page *page) +{ + struct extent_buffer *exists; + + /* + * For subpage case, we completely rely on radix tree to ensure we + * don't try to insert two ebs for the same bytenr. So here we always + * return NULL and just continue. + */ + if (fs_info->nodesize < PAGE_SIZE) + return NULL; + + /* Page not yet attached to an extent buffer */ + if (!PagePrivate(page)) + return NULL; + + /* + * We could have already allocated an eb for this page and attached one + * so lets see if we can get a ref on the existing eb, and if we can we + * know it's good and we can just return that one, else we know we can + * just overwrite page->private. + */ + exists = (struct extent_buffer *)page->private; + if (atomic_inc_not_zero(&exists->refs)) + return exists; + + WARN_ON(PageDirty(page)); + detach_page_private(page); + return NULL; +} + +static int check_eb_alignment(struct btrfs_fs_info *fs_info, u64 start) +{ + if (!IS_ALIGNED(start, fs_info->sectorsize)) { + btrfs_err(fs_info, "bad tree block start %llu", start); + return -EINVAL; + } + + if (fs_info->nodesize < PAGE_SIZE && + offset_in_page(start) + fs_info->nodesize > PAGE_SIZE) { + btrfs_err(fs_info, + "tree block crosses page boundary, start %llu nodesize %u", + start, fs_info->nodesize); + return -EINVAL; + } + if (fs_info->nodesize >= PAGE_SIZE && + !PAGE_ALIGNED(start)) { + btrfs_err(fs_info, + "tree block is not page aligned, start %llu nodesize %u", + start, fs_info->nodesize); + return -EINVAL; + } + return 0; +} + +struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info, + u64 start, u64 owner_root, int level) +{ + unsigned long len = fs_info->nodesize; + int num_pages; + int i; + unsigned long index = start >> PAGE_SHIFT; + struct extent_buffer *eb; + struct extent_buffer *exists = NULL; + struct page *p; + struct address_space *mapping = fs_info->btree_inode->i_mapping; + struct btrfs_subpage *prealloc = NULL; + u64 lockdep_owner = owner_root; + int uptodate = 1; + int ret; + + if (check_eb_alignment(fs_info, start)) + return ERR_PTR(-EINVAL); + +#if BITS_PER_LONG == 32 + if (start >= MAX_LFS_FILESIZE) { + btrfs_err_rl(fs_info, + "extent buffer %llu is beyond 32bit page cache limit", start); + btrfs_err_32bit_limit(fs_info); + return ERR_PTR(-EOVERFLOW); + } + if (start >= BTRFS_32BIT_EARLY_WARN_THRESHOLD) + btrfs_warn_32bit_limit(fs_info); +#endif + + eb = find_extent_buffer(fs_info, start); + if (eb) + return eb; + + eb = __alloc_extent_buffer(fs_info, start, len); + if (!eb) + return ERR_PTR(-ENOMEM); + + /* + * The reloc trees are just snapshots, so we need them to appear to be + * just like any other fs tree WRT lockdep. + */ + if (lockdep_owner == BTRFS_TREE_RELOC_OBJECTID) + lockdep_owner = BTRFS_FS_TREE_OBJECTID; + + btrfs_set_buffer_lockdep_class(lockdep_owner, eb, level); + + num_pages = num_extent_pages(eb); + + /* + * Preallocate page->private for subpage case, so that we won't + * allocate memory with private_lock nor page lock hold. + * + * The memory will be freed by attach_extent_buffer_page() or freed + * manually if we exit earlier. + */ + if (fs_info->nodesize < PAGE_SIZE) { + prealloc = btrfs_alloc_subpage(fs_info, BTRFS_SUBPAGE_METADATA); + if (IS_ERR(prealloc)) { + exists = ERR_CAST(prealloc); + goto free_eb; + } + } + + for (i = 0; i < num_pages; i++, index++) { + p = find_or_create_page(mapping, index, GFP_NOFS|__GFP_NOFAIL); + if (!p) { + exists = ERR_PTR(-ENOMEM); + btrfs_free_subpage(prealloc); + goto free_eb; + } + + spin_lock(&mapping->private_lock); + exists = grab_extent_buffer(fs_info, p); + if (exists) { + spin_unlock(&mapping->private_lock); + unlock_page(p); + put_page(p); + mark_extent_buffer_accessed(exists, p); + btrfs_free_subpage(prealloc); + goto free_eb; + } + /* Should not fail, as we have preallocated the memory */ + ret = attach_extent_buffer_page(eb, p, prealloc); + ASSERT(!ret); + /* + * To inform we have extra eb under allocation, so that + * detach_extent_buffer_page() won't release the page private + * when the eb hasn't yet been inserted into radix tree. + * + * The ref will be decreased when the eb released the page, in + * detach_extent_buffer_page(). + * Thus needs no special handling in error path. + */ + btrfs_page_inc_eb_refs(fs_info, p); + spin_unlock(&mapping->private_lock); + + WARN_ON(btrfs_page_test_dirty(fs_info, p, eb->start, eb->len)); + eb->pages[i] = p; + if (!btrfs_page_test_uptodate(fs_info, p, eb->start, eb->len)) + uptodate = 0; + + /* + * We can't unlock the pages just yet since the extent buffer + * hasn't been properly inserted in the radix tree, this + * opens a race with btree_release_folio which can free a page + * while we are still filling in all pages for the buffer and + * we could crash. + */ + } + if (uptodate) + set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); +again: + ret = radix_tree_preload(GFP_NOFS); + if (ret) { + exists = ERR_PTR(ret); + goto free_eb; + } + + spin_lock(&fs_info->buffer_lock); + ret = radix_tree_insert(&fs_info->buffer_radix, + start >> fs_info->sectorsize_bits, eb); + spin_unlock(&fs_info->buffer_lock); + radix_tree_preload_end(); + if (ret == -EEXIST) { + exists = find_extent_buffer(fs_info, start); + if (exists) + goto free_eb; + else + goto again; + } + /* add one reference for the tree */ + check_buffer_tree_ref(eb); + set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags); + + /* + * Now it's safe to unlock the pages because any calls to + * btree_release_folio will correctly detect that a page belongs to a + * live buffer and won't free them prematurely. + */ + for (i = 0; i < num_pages; i++) + unlock_page(eb->pages[i]); + return eb; + +free_eb: + WARN_ON(!atomic_dec_and_test(&eb->refs)); + for (i = 0; i < num_pages; i++) { + if (eb->pages[i]) + unlock_page(eb->pages[i]); + } + + btrfs_release_extent_buffer(eb); + return exists; +} + +static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head) +{ + struct extent_buffer *eb = + container_of(head, struct extent_buffer, rcu_head); + + __free_extent_buffer(eb); +} + +static int release_extent_buffer(struct extent_buffer *eb) + __releases(&eb->refs_lock) +{ + lockdep_assert_held(&eb->refs_lock); + + WARN_ON(atomic_read(&eb->refs) == 0); + if (atomic_dec_and_test(&eb->refs)) { + if (test_and_clear_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags)) { + struct btrfs_fs_info *fs_info = eb->fs_info; + + spin_unlock(&eb->refs_lock); + + spin_lock(&fs_info->buffer_lock); + radix_tree_delete(&fs_info->buffer_radix, + eb->start >> fs_info->sectorsize_bits); + spin_unlock(&fs_info->buffer_lock); + } else { + spin_unlock(&eb->refs_lock); + } + + btrfs_leak_debug_del_eb(eb); + /* Should be safe to release our pages at this point */ + btrfs_release_extent_buffer_pages(eb); +#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS + if (unlikely(test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags))) { + __free_extent_buffer(eb); + return 1; + } +#endif + call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu); + return 1; + } + spin_unlock(&eb->refs_lock); + + return 0; +} + +void free_extent_buffer(struct extent_buffer *eb) +{ + int refs; + if (!eb) + return; + + refs = atomic_read(&eb->refs); + while (1) { + if ((!test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags) && refs <= 3) + || (test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags) && + refs == 1)) + break; + if (atomic_try_cmpxchg(&eb->refs, &refs, refs - 1)) + return; + } + + spin_lock(&eb->refs_lock); + if (atomic_read(&eb->refs) == 2 && + test_bit(EXTENT_BUFFER_STALE, &eb->bflags) && + !extent_buffer_under_io(eb) && + test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) + atomic_dec(&eb->refs); + + /* + * I know this is terrible, but it's temporary until we stop tracking + * the uptodate bits and such for the extent buffers. + */ + release_extent_buffer(eb); +} + +void free_extent_buffer_stale(struct extent_buffer *eb) +{ + if (!eb) + return; + + spin_lock(&eb->refs_lock); + set_bit(EXTENT_BUFFER_STALE, &eb->bflags); + + if (atomic_read(&eb->refs) == 2 && !extent_buffer_under_io(eb) && + test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) + atomic_dec(&eb->refs); + release_extent_buffer(eb); +} + +static void btree_clear_page_dirty(struct page *page) +{ + ASSERT(PageDirty(page)); + ASSERT(PageLocked(page)); + clear_page_dirty_for_io(page); + xa_lock_irq(&page->mapping->i_pages); + if (!PageDirty(page)) + __xa_clear_mark(&page->mapping->i_pages, + page_index(page), PAGECACHE_TAG_DIRTY); + xa_unlock_irq(&page->mapping->i_pages); +} + +static void clear_subpage_extent_buffer_dirty(const struct extent_buffer *eb) +{ + struct btrfs_fs_info *fs_info = eb->fs_info; + struct page *page = eb->pages[0]; + bool last; + + /* btree_clear_page_dirty() needs page locked */ + lock_page(page); + last = btrfs_subpage_clear_and_test_dirty(fs_info, page, eb->start, + eb->len); + if (last) + btree_clear_page_dirty(page); + unlock_page(page); + WARN_ON(atomic_read(&eb->refs) == 0); +} + +void btrfs_clear_buffer_dirty(struct btrfs_trans_handle *trans, + struct extent_buffer *eb) +{ + struct btrfs_fs_info *fs_info = eb->fs_info; + int i; + int num_pages; + struct page *page; + + btrfs_assert_tree_write_locked(eb); + + if (trans && btrfs_header_generation(eb) != trans->transid) + return; + + if (!test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) + return; + + percpu_counter_add_batch(&fs_info->dirty_metadata_bytes, -eb->len, + fs_info->dirty_metadata_batch); + + if (eb->fs_info->nodesize < PAGE_SIZE) + return clear_subpage_extent_buffer_dirty(eb); + + num_pages = num_extent_pages(eb); + + for (i = 0; i < num_pages; i++) { + page = eb->pages[i]; + if (!PageDirty(page)) + continue; + lock_page(page); + btree_clear_page_dirty(page); + unlock_page(page); + } + WARN_ON(atomic_read(&eb->refs) == 0); +} + +void set_extent_buffer_dirty(struct extent_buffer *eb) +{ + int i; + int num_pages; + bool was_dirty; + + check_buffer_tree_ref(eb); + + was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags); + + num_pages = num_extent_pages(eb); + WARN_ON(atomic_read(&eb->refs) == 0); + WARN_ON(!test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)); + + if (!was_dirty) { + bool subpage = eb->fs_info->nodesize < PAGE_SIZE; + + /* + * For subpage case, we can have other extent buffers in the + * same page, and in clear_subpage_extent_buffer_dirty() we + * have to clear page dirty without subpage lock held. + * This can cause race where our page gets dirty cleared after + * we just set it. + * + * Thankfully, clear_subpage_extent_buffer_dirty() has locked + * its page for other reasons, we can use page lock to prevent + * the above race. + */ + if (subpage) + lock_page(eb->pages[0]); + for (i = 0; i < num_pages; i++) + btrfs_page_set_dirty(eb->fs_info, eb->pages[i], + eb->start, eb->len); + if (subpage) + unlock_page(eb->pages[0]); + percpu_counter_add_batch(&eb->fs_info->dirty_metadata_bytes, + eb->len, + eb->fs_info->dirty_metadata_batch); + } +#ifdef CONFIG_BTRFS_DEBUG + for (i = 0; i < num_pages; i++) + ASSERT(PageDirty(eb->pages[i])); +#endif +} + +void clear_extent_buffer_uptodate(struct extent_buffer *eb) +{ + struct btrfs_fs_info *fs_info = eb->fs_info; + struct page *page; + int num_pages; + int i; + + clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); + num_pages = num_extent_pages(eb); + for (i = 0; i < num_pages; i++) { + page = eb->pages[i]; + if (!page) + continue; + + /* + * This is special handling for metadata subpage, as regular + * btrfs_is_subpage() can not handle cloned/dummy metadata. + */ + if (fs_info->nodesize >= PAGE_SIZE) + ClearPageUptodate(page); + else + btrfs_subpage_clear_uptodate(fs_info, page, eb->start, + eb->len); + } +} + +void set_extent_buffer_uptodate(struct extent_buffer *eb) +{ + struct btrfs_fs_info *fs_info = eb->fs_info; + struct page *page; + int num_pages; + int i; + + set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); + num_pages = num_extent_pages(eb); + for (i = 0; i < num_pages; i++) { + page = eb->pages[i]; + + /* + * This is special handling for metadata subpage, as regular + * btrfs_is_subpage() can not handle cloned/dummy metadata. + */ + if (fs_info->nodesize >= PAGE_SIZE) + SetPageUptodate(page); + else + btrfs_subpage_set_uptodate(fs_info, page, eb->start, + eb->len); + } +} + +static void extent_buffer_read_end_io(struct btrfs_bio *bbio) +{ + struct extent_buffer *eb = bbio->private; + struct btrfs_fs_info *fs_info = eb->fs_info; + bool uptodate = !bbio->bio.bi_status; + struct bvec_iter_all iter_all; + struct bio_vec *bvec; + u32 bio_offset = 0; + + eb->read_mirror = bbio->mirror_num; + + if (uptodate && + btrfs_validate_extent_buffer(eb, &bbio->parent_check) < 0) + uptodate = false; + + if (uptodate) { + set_extent_buffer_uptodate(eb); + } else { + clear_extent_buffer_uptodate(eb); + set_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags); + } + + bio_for_each_segment_all(bvec, &bbio->bio, iter_all) { + u64 start = eb->start + bio_offset; + struct page *page = bvec->bv_page; + u32 len = bvec->bv_len; + + if (uptodate) + btrfs_page_set_uptodate(fs_info, page, start, len); + else + btrfs_page_clear_uptodate(fs_info, page, start, len); + + bio_offset += len; + } + + clear_bit(EXTENT_BUFFER_READING, &eb->bflags); + smp_mb__after_atomic(); + wake_up_bit(&eb->bflags, EXTENT_BUFFER_READING); + free_extent_buffer(eb); + + bio_put(&bbio->bio); +} + +int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num, + struct btrfs_tree_parent_check *check) +{ + int num_pages = num_extent_pages(eb), i; + struct btrfs_bio *bbio; + + if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) + return 0; + + /* + * We could have had EXTENT_BUFFER_UPTODATE cleared by the write + * operation, which could potentially still be in flight. In this case + * we simply want to return an error. + */ + if (unlikely(test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags))) + return -EIO; + + /* Someone else is already reading the buffer, just wait for it. */ + if (test_and_set_bit(EXTENT_BUFFER_READING, &eb->bflags)) + goto done; + + clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags); + eb->read_mirror = 0; + check_buffer_tree_ref(eb); + atomic_inc(&eb->refs); + + bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES, + REQ_OP_READ | REQ_META, eb->fs_info, + extent_buffer_read_end_io, eb); + bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT; + bbio->inode = BTRFS_I(eb->fs_info->btree_inode); + bbio->file_offset = eb->start; + memcpy(&bbio->parent_check, check, sizeof(*check)); + if (eb->fs_info->nodesize < PAGE_SIZE) { + __bio_add_page(&bbio->bio, eb->pages[0], eb->len, + eb->start - page_offset(eb->pages[0])); + } else { + for (i = 0; i < num_pages; i++) + __bio_add_page(&bbio->bio, eb->pages[i], PAGE_SIZE, 0); + } + btrfs_submit_bio(bbio, mirror_num); + +done: + if (wait == WAIT_COMPLETE) { + wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_READING, TASK_UNINTERRUPTIBLE); + if (!test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) + return -EIO; + } + + return 0; +} + +static bool report_eb_range(const struct extent_buffer *eb, unsigned long start, + unsigned long len) +{ + btrfs_warn(eb->fs_info, + "access to eb bytenr %llu len %lu out of range start %lu len %lu", + eb->start, eb->len, start, len); + WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)); + + return true; +} + +/* + * Check if the [start, start + len) range is valid before reading/writing + * the eb. + * NOTE: @start and @len are offset inside the eb, not logical address. + * + * Caller should not touch the dst/src memory if this function returns error. + */ +static inline int check_eb_range(const struct extent_buffer *eb, + unsigned long start, unsigned long len) +{ + unsigned long offset; + + /* start, start + len should not go beyond eb->len nor overflow */ + if (unlikely(check_add_overflow(start, len, &offset) || offset > eb->len)) + return report_eb_range(eb, start, len); + + return false; +} + +void read_extent_buffer(const struct extent_buffer *eb, void *dstv, + unsigned long start, unsigned long len) +{ + size_t cur; + size_t offset; + struct page *page; + char *kaddr; + char *dst = (char *)dstv; + unsigned long i = get_eb_page_index(start); + + if (check_eb_range(eb, start, len)) { + /* + * Invalid range hit, reset the memory, so callers won't get + * some random garbage for their uninitialzed memory. + */ + memset(dstv, 0, len); + return; + } + + offset = get_eb_offset_in_page(eb, start); + + while (len > 0) { + page = eb->pages[i]; + + cur = min(len, (PAGE_SIZE - offset)); + kaddr = page_address(page); + memcpy(dst, kaddr + offset, cur); + + dst += cur; + len -= cur; + offset = 0; + i++; + } +} + +int read_extent_buffer_to_user_nofault(const struct extent_buffer *eb, + void __user *dstv, + unsigned long start, unsigned long len) +{ + size_t cur; + size_t offset; + struct page *page; + char *kaddr; + char __user *dst = (char __user *)dstv; + unsigned long i = get_eb_page_index(start); + int ret = 0; + + WARN_ON(start > eb->len); + WARN_ON(start + len > eb->start + eb->len); + + offset = get_eb_offset_in_page(eb, start); + + while (len > 0) { + page = eb->pages[i]; + + cur = min(len, (PAGE_SIZE - offset)); + kaddr = page_address(page); + if (copy_to_user_nofault(dst, kaddr + offset, cur)) { + ret = -EFAULT; + break; + } + + dst += cur; + len -= cur; + offset = 0; + i++; + } + + return ret; +} + +int memcmp_extent_buffer(const struct extent_buffer *eb, const void *ptrv, + unsigned long start, unsigned long len) +{ + size_t cur; + size_t offset; + struct page *page; + char *kaddr; + char *ptr = (char *)ptrv; + unsigned long i = get_eb_page_index(start); + int ret = 0; + + if (check_eb_range(eb, start, len)) + return -EINVAL; + + offset = get_eb_offset_in_page(eb, start); + + while (len > 0) { + page = eb->pages[i]; + + cur = min(len, (PAGE_SIZE - offset)); + + kaddr = page_address(page); + ret = memcmp(ptr, kaddr + offset, cur); + if (ret) + break; + + ptr += cur; + len -= cur; + offset = 0; + i++; + } + return ret; +} + +/* + * Check that the extent buffer is uptodate. + * + * For regular sector size == PAGE_SIZE case, check if @page is uptodate. + * For subpage case, check if the range covered by the eb has EXTENT_UPTODATE. + */ +static void assert_eb_page_uptodate(const struct extent_buffer *eb, + struct page *page) +{ + struct btrfs_fs_info *fs_info = eb->fs_info; + + /* + * If we are using the commit root we could potentially clear a page + * Uptodate while we're using the extent buffer that we've previously + * looked up. We don't want to complain in this case, as the page was + * valid before, we just didn't write it out. Instead we want to catch + * the case where we didn't actually read the block properly, which + * would have !PageUptodate and !EXTENT_BUFFER_WRITE_ERR. + */ + if (test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)) + return; + + if (fs_info->nodesize < PAGE_SIZE) { + if (WARN_ON(!btrfs_subpage_test_uptodate(fs_info, page, + eb->start, eb->len))) + btrfs_subpage_dump_bitmap(fs_info, page, eb->start, eb->len); + } else { + WARN_ON(!PageUptodate(page)); + } +} + +static void __write_extent_buffer(const struct extent_buffer *eb, + const void *srcv, unsigned long start, + unsigned long len, bool use_memmove) +{ + size_t cur; + size_t offset; + struct page *page; + char *kaddr; + char *src = (char *)srcv; + unsigned long i = get_eb_page_index(start); + /* For unmapped (dummy) ebs, no need to check their uptodate status. */ + const bool check_uptodate = !test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags); + + WARN_ON(test_bit(EXTENT_BUFFER_NO_CHECK, &eb->bflags)); + + if (check_eb_range(eb, start, len)) + return; + + offset = get_eb_offset_in_page(eb, start); + + while (len > 0) { + page = eb->pages[i]; + if (check_uptodate) + assert_eb_page_uptodate(eb, page); + + cur = min(len, PAGE_SIZE - offset); + kaddr = page_address(page); + if (use_memmove) + memmove(kaddr + offset, src, cur); + else + memcpy(kaddr + offset, src, cur); + + src += cur; + len -= cur; + offset = 0; + i++; + } +} + +void write_extent_buffer(const struct extent_buffer *eb, const void *srcv, + unsigned long start, unsigned long len) +{ + return __write_extent_buffer(eb, srcv, start, len, false); +} + +static void memset_extent_buffer(const struct extent_buffer *eb, int c, + unsigned long start, unsigned long len) +{ + unsigned long cur = start; + + while (cur < start + len) { + unsigned long index = get_eb_page_index(cur); + unsigned int offset = get_eb_offset_in_page(eb, cur); + unsigned int cur_len = min(start + len - cur, PAGE_SIZE - offset); + struct page *page = eb->pages[index]; + + assert_eb_page_uptodate(eb, page); + memset(page_address(page) + offset, c, cur_len); + + cur += cur_len; + } +} + +void memzero_extent_buffer(const struct extent_buffer *eb, unsigned long start, + unsigned long len) +{ + if (check_eb_range(eb, start, len)) + return; + return memset_extent_buffer(eb, 0, start, len); +} + +void copy_extent_buffer_full(const struct extent_buffer *dst, + const struct extent_buffer *src) +{ + unsigned long cur = 0; + + ASSERT(dst->len == src->len); + + while (cur < src->len) { + unsigned long index = get_eb_page_index(cur); + unsigned long offset = get_eb_offset_in_page(src, cur); + unsigned long cur_len = min(src->len, PAGE_SIZE - offset); + void *addr = page_address(src->pages[index]) + offset; + + write_extent_buffer(dst, addr, cur, cur_len); + + cur += cur_len; + } +} + +void copy_extent_buffer(const struct extent_buffer *dst, + const struct extent_buffer *src, + unsigned long dst_offset, unsigned long src_offset, + unsigned long len) +{ + u64 dst_len = dst->len; + size_t cur; + size_t offset; + struct page *page; + char *kaddr; + unsigned long i = get_eb_page_index(dst_offset); + + if (check_eb_range(dst, dst_offset, len) || + check_eb_range(src, src_offset, len)) + return; + + WARN_ON(src->len != dst_len); + + offset = get_eb_offset_in_page(dst, dst_offset); + + while (len > 0) { + page = dst->pages[i]; + assert_eb_page_uptodate(dst, page); + + cur = min(len, (unsigned long)(PAGE_SIZE - offset)); + + kaddr = page_address(page); + read_extent_buffer(src, kaddr + offset, src_offset, cur); + + src_offset += cur; + len -= cur; + offset = 0; + i++; + } +} + +/* + * eb_bitmap_offset() - calculate the page and offset of the byte containing the + * given bit number + * @eb: the extent buffer + * @start: offset of the bitmap item in the extent buffer + * @nr: bit number + * @page_index: return index of the page in the extent buffer that contains the + * given bit number + * @page_offset: return offset into the page given by page_index + * + * This helper hides the ugliness of finding the byte in an extent buffer which + * contains a given bit. + */ +static inline void eb_bitmap_offset(const struct extent_buffer *eb, + unsigned long start, unsigned long nr, + unsigned long *page_index, + size_t *page_offset) +{ + size_t byte_offset = BIT_BYTE(nr); + size_t offset; + + /* + * The byte we want is the offset of the extent buffer + the offset of + * the bitmap item in the extent buffer + the offset of the byte in the + * bitmap item. + */ + offset = start + offset_in_page(eb->start) + byte_offset; + + *page_index = offset >> PAGE_SHIFT; + *page_offset = offset_in_page(offset); +} + +/* + * Determine whether a bit in a bitmap item is set. + * + * @eb: the extent buffer + * @start: offset of the bitmap item in the extent buffer + * @nr: bit number to test + */ +int extent_buffer_test_bit(const struct extent_buffer *eb, unsigned long start, + unsigned long nr) +{ + u8 *kaddr; + struct page *page; + unsigned long i; + size_t offset; + + eb_bitmap_offset(eb, start, nr, &i, &offset); + page = eb->pages[i]; + assert_eb_page_uptodate(eb, page); + kaddr = page_address(page); + return 1U & (kaddr[offset] >> (nr & (BITS_PER_BYTE - 1))); +} + +static u8 *extent_buffer_get_byte(const struct extent_buffer *eb, unsigned long bytenr) +{ + unsigned long index = get_eb_page_index(bytenr); + + if (check_eb_range(eb, bytenr, 1)) + return NULL; + return page_address(eb->pages[index]) + get_eb_offset_in_page(eb, bytenr); +} + +/* + * Set an area of a bitmap to 1. + * + * @eb: the extent buffer + * @start: offset of the bitmap item in the extent buffer + * @pos: bit number of the first bit + * @len: number of bits to set + */ +void extent_buffer_bitmap_set(const struct extent_buffer *eb, unsigned long start, + unsigned long pos, unsigned long len) +{ + unsigned int first_byte = start + BIT_BYTE(pos); + unsigned int last_byte = start + BIT_BYTE(pos + len - 1); + const bool same_byte = (first_byte == last_byte); + u8 mask = BITMAP_FIRST_BYTE_MASK(pos); + u8 *kaddr; + + if (same_byte) + mask &= BITMAP_LAST_BYTE_MASK(pos + len); + + /* Handle the first byte. */ + kaddr = extent_buffer_get_byte(eb, first_byte); + *kaddr |= mask; + if (same_byte) + return; + + /* Handle the byte aligned part. */ + ASSERT(first_byte + 1 <= last_byte); + memset_extent_buffer(eb, 0xff, first_byte + 1, last_byte - first_byte - 1); + + /* Handle the last byte. */ + kaddr = extent_buffer_get_byte(eb, last_byte); + *kaddr |= BITMAP_LAST_BYTE_MASK(pos + len); +} + + +/* + * Clear an area of a bitmap. + * + * @eb: the extent buffer + * @start: offset of the bitmap item in the extent buffer + * @pos: bit number of the first bit + * @len: number of bits to clear + */ +void extent_buffer_bitmap_clear(const struct extent_buffer *eb, + unsigned long start, unsigned long pos, + unsigned long len) +{ + unsigned int first_byte = start + BIT_BYTE(pos); + unsigned int last_byte = start + BIT_BYTE(pos + len - 1); + const bool same_byte = (first_byte == last_byte); + u8 mask = BITMAP_FIRST_BYTE_MASK(pos); + u8 *kaddr; + + if (same_byte) + mask &= BITMAP_LAST_BYTE_MASK(pos + len); + + /* Handle the first byte. */ + kaddr = extent_buffer_get_byte(eb, first_byte); + *kaddr &= ~mask; + if (same_byte) + return; + + /* Handle the byte aligned part. */ + ASSERT(first_byte + 1 <= last_byte); + memset_extent_buffer(eb, 0, first_byte + 1, last_byte - first_byte - 1); + + /* Handle the last byte. */ + kaddr = extent_buffer_get_byte(eb, last_byte); + *kaddr &= ~BITMAP_LAST_BYTE_MASK(pos + len); +} + +static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len) +{ + unsigned long distance = (src > dst) ? src - dst : dst - src; + return distance < len; +} + +void memcpy_extent_buffer(const struct extent_buffer *dst, + unsigned long dst_offset, unsigned long src_offset, + unsigned long len) +{ + unsigned long cur_off = 0; + + if (check_eb_range(dst, dst_offset, len) || + check_eb_range(dst, src_offset, len)) + return; + + while (cur_off < len) { + unsigned long cur_src = cur_off + src_offset; + unsigned long pg_index = get_eb_page_index(cur_src); + unsigned long pg_off = get_eb_offset_in_page(dst, cur_src); + unsigned long cur_len = min(src_offset + len - cur_src, + PAGE_SIZE - pg_off); + void *src_addr = page_address(dst->pages[pg_index]) + pg_off; + const bool use_memmove = areas_overlap(src_offset + cur_off, + dst_offset + cur_off, cur_len); + + __write_extent_buffer(dst, src_addr, dst_offset + cur_off, cur_len, + use_memmove); + cur_off += cur_len; + } +} + +void memmove_extent_buffer(const struct extent_buffer *dst, + unsigned long dst_offset, unsigned long src_offset, + unsigned long len) +{ + unsigned long dst_end = dst_offset + len - 1; + unsigned long src_end = src_offset + len - 1; + + if (check_eb_range(dst, dst_offset, len) || + check_eb_range(dst, src_offset, len)) + return; + + if (dst_offset < src_offset) { + memcpy_extent_buffer(dst, dst_offset, src_offset, len); + return; + } + + while (len > 0) { + unsigned long src_i; + size_t cur; + size_t dst_off_in_page; + size_t src_off_in_page; + void *src_addr; + bool use_memmove; + + src_i = get_eb_page_index(src_end); + + dst_off_in_page = get_eb_offset_in_page(dst, dst_end); + src_off_in_page = get_eb_offset_in_page(dst, src_end); + + cur = min_t(unsigned long, len, src_off_in_page + 1); + cur = min(cur, dst_off_in_page + 1); + + src_addr = page_address(dst->pages[src_i]) + src_off_in_page - + cur + 1; + use_memmove = areas_overlap(src_end - cur + 1, dst_end - cur + 1, + cur); + + __write_extent_buffer(dst, src_addr, dst_end - cur + 1, cur, + use_memmove); + + dst_end -= cur; + src_end -= cur; + len -= cur; + } +} + +#define GANG_LOOKUP_SIZE 16 +static struct extent_buffer *get_next_extent_buffer( + struct btrfs_fs_info *fs_info, struct page *page, u64 bytenr) +{ + struct extent_buffer *gang[GANG_LOOKUP_SIZE]; + struct extent_buffer *found = NULL; + u64 page_start = page_offset(page); + u64 cur = page_start; + + ASSERT(in_range(bytenr, page_start, PAGE_SIZE)); + lockdep_assert_held(&fs_info->buffer_lock); + + while (cur < page_start + PAGE_SIZE) { + int ret; + int i; + + ret = radix_tree_gang_lookup(&fs_info->buffer_radix, + (void **)gang, cur >> fs_info->sectorsize_bits, + min_t(unsigned int, GANG_LOOKUP_SIZE, + PAGE_SIZE / fs_info->nodesize)); + if (ret == 0) + goto out; + for (i = 0; i < ret; i++) { + /* Already beyond page end */ + if (gang[i]->start >= page_start + PAGE_SIZE) + goto out; + /* Found one */ + if (gang[i]->start >= bytenr) { + found = gang[i]; + goto out; + } + } + cur = gang[ret - 1]->start + gang[ret - 1]->len; + } +out: + return found; +} + +static int try_release_subpage_extent_buffer(struct page *page) +{ + struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb); + u64 cur = page_offset(page); + const u64 end = page_offset(page) + PAGE_SIZE; + int ret; + + while (cur < end) { + struct extent_buffer *eb = NULL; + + /* + * Unlike try_release_extent_buffer() which uses page->private + * to grab buffer, for subpage case we rely on radix tree, thus + * we need to ensure radix tree consistency. + * + * We also want an atomic snapshot of the radix tree, thus go + * with spinlock rather than RCU. + */ + spin_lock(&fs_info->buffer_lock); + eb = get_next_extent_buffer(fs_info, page, cur); + if (!eb) { + /* No more eb in the page range after or at cur */ + spin_unlock(&fs_info->buffer_lock); + break; + } + cur = eb->start + eb->len; + + /* + * The same as try_release_extent_buffer(), to ensure the eb + * won't disappear out from under us. + */ + spin_lock(&eb->refs_lock); + if (atomic_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) { + spin_unlock(&eb->refs_lock); + spin_unlock(&fs_info->buffer_lock); + break; + } + spin_unlock(&fs_info->buffer_lock); + + /* + * If tree ref isn't set then we know the ref on this eb is a + * real ref, so just return, this eb will likely be freed soon + * anyway. + */ + if (!test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) { + spin_unlock(&eb->refs_lock); + break; + } + + /* + * Here we don't care about the return value, we will always + * check the page private at the end. And + * release_extent_buffer() will release the refs_lock. + */ + release_extent_buffer(eb); + } + /* + * Finally to check if we have cleared page private, as if we have + * released all ebs in the page, the page private should be cleared now. + */ + spin_lock(&page->mapping->private_lock); + if (!PagePrivate(page)) + ret = 1; + else + ret = 0; + spin_unlock(&page->mapping->private_lock); + return ret; + +} + +int try_release_extent_buffer(struct page *page) +{ + struct extent_buffer *eb; + + if (btrfs_sb(page->mapping->host->i_sb)->nodesize < PAGE_SIZE) + return try_release_subpage_extent_buffer(page); + + /* + * We need to make sure nobody is changing page->private, as we rely on + * page->private as the pointer to extent buffer. + */ + spin_lock(&page->mapping->private_lock); + if (!PagePrivate(page)) { + spin_unlock(&page->mapping->private_lock); + return 1; + } + + eb = (struct extent_buffer *)page->private; + BUG_ON(!eb); + + /* + * This is a little awful but should be ok, we need to make sure that + * the eb doesn't disappear out from under us while we're looking at + * this page. + */ + spin_lock(&eb->refs_lock); + if (atomic_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) { + spin_unlock(&eb->refs_lock); + spin_unlock(&page->mapping->private_lock); + return 0; + } + spin_unlock(&page->mapping->private_lock); + + /* + * If tree ref isn't set then we know the ref on this eb is a real ref, + * so just return, this page will likely be freed soon anyway. + */ + if (!test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) { + spin_unlock(&eb->refs_lock); + return 0; + } + + return release_extent_buffer(eb); +} + +/* + * btrfs_readahead_tree_block - attempt to readahead a child block + * @fs_info: the fs_info + * @bytenr: bytenr to read + * @owner_root: objectid of the root that owns this eb + * @gen: generation for the uptodate check, can be 0 + * @level: level for the eb + * + * Attempt to readahead a tree block at @bytenr. If @gen is 0 then we do a + * normal uptodate check of the eb, without checking the generation. If we have + * to read the block we will not block on anything. + */ +void btrfs_readahead_tree_block(struct btrfs_fs_info *fs_info, + u64 bytenr, u64 owner_root, u64 gen, int level) +{ + struct btrfs_tree_parent_check check = { + .has_first_key = 0, + .level = level, + .transid = gen + }; + struct extent_buffer *eb; + int ret; + + eb = btrfs_find_create_tree_block(fs_info, bytenr, owner_root, level); + if (IS_ERR(eb)) + return; + + if (btrfs_buffer_uptodate(eb, gen, 1)) { + free_extent_buffer(eb); + return; + } + + ret = read_extent_buffer_pages(eb, WAIT_NONE, 0, &check); + if (ret < 0) + free_extent_buffer_stale(eb); + else + free_extent_buffer(eb); +} + +/* + * btrfs_readahead_node_child - readahead a node's child block + * @node: parent node we're reading from + * @slot: slot in the parent node for the child we want to read + * + * A helper for btrfs_readahead_tree_block, we simply read the bytenr pointed at + * the slot in the node provided. + */ +void btrfs_readahead_node_child(struct extent_buffer *node, int slot) +{ + btrfs_readahead_tree_block(node->fs_info, + btrfs_node_blockptr(node, slot), + btrfs_header_owner(node), + btrfs_node_ptr_generation(node, slot), + btrfs_header_level(node) - 1); +} |