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-rw-r--r--fs/btrfs/extent_io.c4676
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);
+}