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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /fs/squashfs/file.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fs/squashfs/file.c')
-rw-r--r--fs/squashfs/file.c638
1 files changed, 638 insertions, 0 deletions
diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
new file mode 100644
index 0000000000..8ba8c4c507
--- /dev/null
+++ b/fs/squashfs/file.c
@@ -0,0 +1,638 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ * Phillip Lougher <phillip@squashfs.org.uk>
+ *
+ * file.c
+ */
+
+/*
+ * This file contains code for handling regular files. A regular file
+ * consists of a sequence of contiguous compressed blocks, and/or a
+ * compressed fragment block (tail-end packed block). The compressed size
+ * of each datablock is stored in a block list contained within the
+ * file inode (itself stored in one or more compressed metadata blocks).
+ *
+ * To speed up access to datablocks when reading 'large' files (256 Mbytes or
+ * larger), the code implements an index cache that caches the mapping from
+ * block index to datablock location on disk.
+ *
+ * The index cache allows Squashfs to handle large files (up to 1.75 TiB) while
+ * retaining a simple and space-efficient block list on disk. The cache
+ * is split into slots, caching up to eight 224 GiB files (128 KiB blocks).
+ * Larger files use multiple slots, with 1.75 TiB files using all 8 slots.
+ * The index cache is designed to be memory efficient, and by default uses
+ * 16 KiB.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/pagemap.h>
+#include <linux/mutex.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+#include "page_actor.h"
+
+/*
+ * Locate cache slot in range [offset, index] for specified inode. If
+ * there's more than one return the slot closest to index.
+ */
+static struct meta_index *locate_meta_index(struct inode *inode, int offset,
+ int index)
+{
+ struct meta_index *meta = NULL;
+ struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+ int i;
+
+ mutex_lock(&msblk->meta_index_mutex);
+
+ TRACE("locate_meta_index: index %d, offset %d\n", index, offset);
+
+ if (msblk->meta_index == NULL)
+ goto not_allocated;
+
+ for (i = 0; i < SQUASHFS_META_SLOTS; i++) {
+ if (msblk->meta_index[i].inode_number == inode->i_ino &&
+ msblk->meta_index[i].offset >= offset &&
+ msblk->meta_index[i].offset <= index &&
+ msblk->meta_index[i].locked == 0) {
+ TRACE("locate_meta_index: entry %d, offset %d\n", i,
+ msblk->meta_index[i].offset);
+ meta = &msblk->meta_index[i];
+ offset = meta->offset;
+ }
+ }
+
+ if (meta)
+ meta->locked = 1;
+
+not_allocated:
+ mutex_unlock(&msblk->meta_index_mutex);
+
+ return meta;
+}
+
+
+/*
+ * Find and initialise an empty cache slot for index offset.
+ */
+static struct meta_index *empty_meta_index(struct inode *inode, int offset,
+ int skip)
+{
+ struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+ struct meta_index *meta = NULL;
+ int i;
+
+ mutex_lock(&msblk->meta_index_mutex);
+
+ TRACE("empty_meta_index: offset %d, skip %d\n", offset, skip);
+
+ if (msblk->meta_index == NULL) {
+ /*
+ * First time cache index has been used, allocate and
+ * initialise. The cache index could be allocated at
+ * mount time but doing it here means it is allocated only
+ * if a 'large' file is read.
+ */
+ msblk->meta_index = kcalloc(SQUASHFS_META_SLOTS,
+ sizeof(*(msblk->meta_index)), GFP_KERNEL);
+ if (msblk->meta_index == NULL) {
+ ERROR("Failed to allocate meta_index\n");
+ goto failed;
+ }
+ for (i = 0; i < SQUASHFS_META_SLOTS; i++) {
+ msblk->meta_index[i].inode_number = 0;
+ msblk->meta_index[i].locked = 0;
+ }
+ msblk->next_meta_index = 0;
+ }
+
+ for (i = SQUASHFS_META_SLOTS; i &&
+ msblk->meta_index[msblk->next_meta_index].locked; i--)
+ msblk->next_meta_index = (msblk->next_meta_index + 1) %
+ SQUASHFS_META_SLOTS;
+
+ if (i == 0) {
+ TRACE("empty_meta_index: failed!\n");
+ goto failed;
+ }
+
+ TRACE("empty_meta_index: returned meta entry %d, %p\n",
+ msblk->next_meta_index,
+ &msblk->meta_index[msblk->next_meta_index]);
+
+ meta = &msblk->meta_index[msblk->next_meta_index];
+ msblk->next_meta_index = (msblk->next_meta_index + 1) %
+ SQUASHFS_META_SLOTS;
+
+ meta->inode_number = inode->i_ino;
+ meta->offset = offset;
+ meta->skip = skip;
+ meta->entries = 0;
+ meta->locked = 1;
+
+failed:
+ mutex_unlock(&msblk->meta_index_mutex);
+ return meta;
+}
+
+
+static void release_meta_index(struct inode *inode, struct meta_index *meta)
+{
+ struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+ mutex_lock(&msblk->meta_index_mutex);
+ meta->locked = 0;
+ mutex_unlock(&msblk->meta_index_mutex);
+}
+
+
+/*
+ * Read the next n blocks from the block list, starting from
+ * metadata block <start_block, offset>.
+ */
+static long long read_indexes(struct super_block *sb, int n,
+ u64 *start_block, int *offset)
+{
+ int err, i;
+ long long block = 0;
+ __le32 *blist = kmalloc(PAGE_SIZE, GFP_KERNEL);
+
+ if (blist == NULL) {
+ ERROR("read_indexes: Failed to allocate block_list\n");
+ return -ENOMEM;
+ }
+
+ while (n) {
+ int blocks = min_t(int, n, PAGE_SIZE >> 2);
+
+ err = squashfs_read_metadata(sb, blist, start_block,
+ offset, blocks << 2);
+ if (err < 0) {
+ ERROR("read_indexes: reading block [%llx:%x]\n",
+ *start_block, *offset);
+ goto failure;
+ }
+
+ for (i = 0; i < blocks; i++) {
+ int size = squashfs_block_size(blist[i]);
+ if (size < 0) {
+ err = size;
+ goto failure;
+ }
+ block += SQUASHFS_COMPRESSED_SIZE_BLOCK(size);
+ }
+ n -= blocks;
+ }
+
+ kfree(blist);
+ return block;
+
+failure:
+ kfree(blist);
+ return err;
+}
+
+
+/*
+ * Each cache index slot has SQUASHFS_META_ENTRIES, each of which
+ * can cache one index -> datablock/blocklist-block mapping. We wish
+ * to distribute these over the length of the file, entry[0] maps index x,
+ * entry[1] maps index x + skip, entry[2] maps index x + 2 * skip, and so on.
+ * The larger the file, the greater the skip factor. The skip factor is
+ * limited to the size of the metadata cache (SQUASHFS_CACHED_BLKS) to ensure
+ * the number of metadata blocks that need to be read fits into the cache.
+ * If the skip factor is limited in this way then the file will use multiple
+ * slots.
+ */
+static inline int calculate_skip(u64 blocks)
+{
+ u64 skip = blocks / ((SQUASHFS_META_ENTRIES + 1)
+ * SQUASHFS_META_INDEXES);
+ return min((u64) SQUASHFS_CACHED_BLKS - 1, skip + 1);
+}
+
+
+/*
+ * Search and grow the index cache for the specified inode, returning the
+ * on-disk locations of the datablock and block list metadata block
+ * <index_block, index_offset> for index (scaled to nearest cache index).
+ */
+static int fill_meta_index(struct inode *inode, int index,
+ u64 *index_block, int *index_offset, u64 *data_block)
+{
+ struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+ int skip = calculate_skip(i_size_read(inode) >> msblk->block_log);
+ int offset = 0;
+ struct meta_index *meta;
+ struct meta_entry *meta_entry;
+ u64 cur_index_block = squashfs_i(inode)->block_list_start;
+ int cur_offset = squashfs_i(inode)->offset;
+ u64 cur_data_block = squashfs_i(inode)->start;
+ int err, i;
+
+ /*
+ * Scale index to cache index (cache slot entry)
+ */
+ index /= SQUASHFS_META_INDEXES * skip;
+
+ while (offset < index) {
+ meta = locate_meta_index(inode, offset + 1, index);
+
+ if (meta == NULL) {
+ meta = empty_meta_index(inode, offset + 1, skip);
+ if (meta == NULL)
+ goto all_done;
+ } else {
+ offset = index < meta->offset + meta->entries ? index :
+ meta->offset + meta->entries - 1;
+ meta_entry = &meta->meta_entry[offset - meta->offset];
+ cur_index_block = meta_entry->index_block +
+ msblk->inode_table;
+ cur_offset = meta_entry->offset;
+ cur_data_block = meta_entry->data_block;
+ TRACE("get_meta_index: offset %d, meta->offset %d, "
+ "meta->entries %d\n", offset, meta->offset,
+ meta->entries);
+ TRACE("get_meta_index: index_block 0x%llx, offset 0x%x"
+ " data_block 0x%llx\n", cur_index_block,
+ cur_offset, cur_data_block);
+ }
+
+ /*
+ * If necessary grow cache slot by reading block list. Cache
+ * slot is extended up to index or to the end of the slot, in
+ * which case further slots will be used.
+ */
+ for (i = meta->offset + meta->entries; i <= index &&
+ i < meta->offset + SQUASHFS_META_ENTRIES; i++) {
+ int blocks = skip * SQUASHFS_META_INDEXES;
+ long long res = read_indexes(inode->i_sb, blocks,
+ &cur_index_block, &cur_offset);
+
+ if (res < 0) {
+ if (meta->entries == 0)
+ /*
+ * Don't leave an empty slot on read
+ * error allocated to this inode...
+ */
+ meta->inode_number = 0;
+ err = res;
+ goto failed;
+ }
+
+ cur_data_block += res;
+ meta_entry = &meta->meta_entry[i - meta->offset];
+ meta_entry->index_block = cur_index_block -
+ msblk->inode_table;
+ meta_entry->offset = cur_offset;
+ meta_entry->data_block = cur_data_block;
+ meta->entries++;
+ offset++;
+ }
+
+ TRACE("get_meta_index: meta->offset %d, meta->entries %d\n",
+ meta->offset, meta->entries);
+
+ release_meta_index(inode, meta);
+ }
+
+all_done:
+ *index_block = cur_index_block;
+ *index_offset = cur_offset;
+ *data_block = cur_data_block;
+
+ /*
+ * Scale cache index (cache slot entry) to index
+ */
+ return offset * SQUASHFS_META_INDEXES * skip;
+
+failed:
+ release_meta_index(inode, meta);
+ return err;
+}
+
+
+/*
+ * Get the on-disk location and compressed size of the datablock
+ * specified by index. Fill_meta_index() does most of the work.
+ */
+static int read_blocklist(struct inode *inode, int index, u64 *block)
+{
+ u64 start;
+ long long blks;
+ int offset;
+ __le32 size;
+ int res = fill_meta_index(inode, index, &start, &offset, block);
+
+ TRACE("read_blocklist: res %d, index %d, start 0x%llx, offset"
+ " 0x%x, block 0x%llx\n", res, index, start, offset,
+ *block);
+
+ if (res < 0)
+ return res;
+
+ /*
+ * res contains the index of the mapping returned by fill_meta_index(),
+ * this will likely be less than the desired index (because the
+ * meta_index cache works at a higher granularity). Read any
+ * extra block indexes needed.
+ */
+ if (res < index) {
+ blks = read_indexes(inode->i_sb, index - res, &start, &offset);
+ if (blks < 0)
+ return (int) blks;
+ *block += blks;
+ }
+
+ /*
+ * Read length of block specified by index.
+ */
+ res = squashfs_read_metadata(inode->i_sb, &size, &start, &offset,
+ sizeof(size));
+ if (res < 0)
+ return res;
+ return squashfs_block_size(size);
+}
+
+void squashfs_fill_page(struct page *page, struct squashfs_cache_entry *buffer, int offset, int avail)
+{
+ int copied;
+ void *pageaddr;
+
+ pageaddr = kmap_atomic(page);
+ copied = squashfs_copy_data(pageaddr, buffer, offset, avail);
+ memset(pageaddr + copied, 0, PAGE_SIZE - copied);
+ kunmap_atomic(pageaddr);
+
+ flush_dcache_page(page);
+ if (copied == avail)
+ SetPageUptodate(page);
+ else
+ SetPageError(page);
+}
+
+/* Copy data into page cache */
+void squashfs_copy_cache(struct page *page, struct squashfs_cache_entry *buffer,
+ int bytes, int offset)
+{
+ struct inode *inode = page->mapping->host;
+ struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+ int i, mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
+ int start_index = page->index & ~mask, end_index = start_index | mask;
+
+ /*
+ * Loop copying datablock into pages. As the datablock likely covers
+ * many PAGE_SIZE pages (default block size is 128 KiB) explicitly
+ * grab the pages from the page cache, except for the page that we've
+ * been called to fill.
+ */
+ for (i = start_index; i <= end_index && bytes > 0; i++,
+ bytes -= PAGE_SIZE, offset += PAGE_SIZE) {
+ struct page *push_page;
+ int avail = buffer ? min_t(int, bytes, PAGE_SIZE) : 0;
+
+ TRACE("bytes %d, i %d, available_bytes %d\n", bytes, i, avail);
+
+ push_page = (i == page->index) ? page :
+ grab_cache_page_nowait(page->mapping, i);
+
+ if (!push_page)
+ continue;
+
+ if (PageUptodate(push_page))
+ goto skip_page;
+
+ squashfs_fill_page(push_page, buffer, offset, avail);
+skip_page:
+ unlock_page(push_page);
+ if (i != page->index)
+ put_page(push_page);
+ }
+}
+
+/* Read datablock stored packed inside a fragment (tail-end packed block) */
+static int squashfs_readpage_fragment(struct page *page, int expected)
+{
+ struct inode *inode = page->mapping->host;
+ struct squashfs_cache_entry *buffer = squashfs_get_fragment(inode->i_sb,
+ squashfs_i(inode)->fragment_block,
+ squashfs_i(inode)->fragment_size);
+ int res = buffer->error;
+
+ if (res)
+ ERROR("Unable to read page, block %llx, size %x\n",
+ squashfs_i(inode)->fragment_block,
+ squashfs_i(inode)->fragment_size);
+ else
+ squashfs_copy_cache(page, buffer, expected,
+ squashfs_i(inode)->fragment_offset);
+
+ squashfs_cache_put(buffer);
+ return res;
+}
+
+static int squashfs_readpage_sparse(struct page *page, int expected)
+{
+ squashfs_copy_cache(page, NULL, expected, 0);
+ return 0;
+}
+
+static int squashfs_read_folio(struct file *file, struct folio *folio)
+{
+ struct page *page = &folio->page;
+ struct inode *inode = page->mapping->host;
+ struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+ int index = page->index >> (msblk->block_log - PAGE_SHIFT);
+ int file_end = i_size_read(inode) >> msblk->block_log;
+ int expected = index == file_end ?
+ (i_size_read(inode) & (msblk->block_size - 1)) :
+ msblk->block_size;
+ int res = 0;
+ void *pageaddr;
+
+ TRACE("Entered squashfs_readpage, page index %lx, start block %llx\n",
+ page->index, squashfs_i(inode)->start);
+
+ if (page->index >= ((i_size_read(inode) + PAGE_SIZE - 1) >>
+ PAGE_SHIFT))
+ goto out;
+
+ if (index < file_end || squashfs_i(inode)->fragment_block ==
+ SQUASHFS_INVALID_BLK) {
+ u64 block = 0;
+
+ res = read_blocklist(inode, index, &block);
+ if (res < 0)
+ goto error_out;
+
+ if (res == 0)
+ res = squashfs_readpage_sparse(page, expected);
+ else
+ res = squashfs_readpage_block(page, block, res, expected);
+ } else
+ res = squashfs_readpage_fragment(page, expected);
+
+ if (!res)
+ return 0;
+
+error_out:
+ SetPageError(page);
+out:
+ pageaddr = kmap_atomic(page);
+ memset(pageaddr, 0, PAGE_SIZE);
+ kunmap_atomic(pageaddr);
+ flush_dcache_page(page);
+ if (res == 0)
+ SetPageUptodate(page);
+ unlock_page(page);
+
+ return res;
+}
+
+static int squashfs_readahead_fragment(struct page **page,
+ unsigned int pages, unsigned int expected)
+{
+ struct inode *inode = page[0]->mapping->host;
+ struct squashfs_cache_entry *buffer = squashfs_get_fragment(inode->i_sb,
+ squashfs_i(inode)->fragment_block,
+ squashfs_i(inode)->fragment_size);
+ struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+ unsigned int n, mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
+ int error = buffer->error;
+
+ if (error)
+ goto out;
+
+ expected += squashfs_i(inode)->fragment_offset;
+
+ for (n = 0; n < pages; n++) {
+ unsigned int base = (page[n]->index & mask) << PAGE_SHIFT;
+ unsigned int offset = base + squashfs_i(inode)->fragment_offset;
+
+ if (expected > offset) {
+ unsigned int avail = min_t(unsigned int, expected -
+ offset, PAGE_SIZE);
+
+ squashfs_fill_page(page[n], buffer, offset, avail);
+ }
+
+ unlock_page(page[n]);
+ put_page(page[n]);
+ }
+
+out:
+ squashfs_cache_put(buffer);
+ return error;
+}
+
+static void squashfs_readahead(struct readahead_control *ractl)
+{
+ struct inode *inode = ractl->mapping->host;
+ struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+ size_t mask = (1UL << msblk->block_log) - 1;
+ unsigned short shift = msblk->block_log - PAGE_SHIFT;
+ loff_t start = readahead_pos(ractl) & ~mask;
+ size_t len = readahead_length(ractl) + readahead_pos(ractl) - start;
+ struct squashfs_page_actor *actor;
+ unsigned int nr_pages = 0;
+ struct page **pages;
+ int i, file_end = i_size_read(inode) >> msblk->block_log;
+ unsigned int max_pages = 1UL << shift;
+
+ readahead_expand(ractl, start, (len | mask) + 1);
+
+ pages = kmalloc_array(max_pages, sizeof(void *), GFP_KERNEL);
+ if (!pages)
+ return;
+
+ for (;;) {
+ pgoff_t index;
+ int res, bsize;
+ u64 block = 0;
+ unsigned int expected;
+ struct page *last_page;
+
+ expected = start >> msblk->block_log == file_end ?
+ (i_size_read(inode) & (msblk->block_size - 1)) :
+ msblk->block_size;
+
+ max_pages = (expected + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+ nr_pages = __readahead_batch(ractl, pages, max_pages);
+ if (!nr_pages)
+ break;
+
+ if (readahead_pos(ractl) >= i_size_read(inode))
+ goto skip_pages;
+
+ index = pages[0]->index >> shift;
+
+ if ((pages[nr_pages - 1]->index >> shift) != index)
+ goto skip_pages;
+
+ if (index == file_end && squashfs_i(inode)->fragment_block !=
+ SQUASHFS_INVALID_BLK) {
+ res = squashfs_readahead_fragment(pages, nr_pages,
+ expected);
+ if (res)
+ goto skip_pages;
+ continue;
+ }
+
+ bsize = read_blocklist(inode, index, &block);
+ if (bsize == 0)
+ goto skip_pages;
+
+ actor = squashfs_page_actor_init_special(msblk, pages, nr_pages,
+ expected);
+ if (!actor)
+ goto skip_pages;
+
+ res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
+
+ last_page = squashfs_page_actor_free(actor);
+
+ if (res == expected) {
+ int bytes;
+
+ /* Last page (if present) may have trailing bytes not filled */
+ bytes = res % PAGE_SIZE;
+ if (index == file_end && bytes && last_page)
+ memzero_page(last_page, bytes,
+ PAGE_SIZE - bytes);
+
+ for (i = 0; i < nr_pages; i++) {
+ flush_dcache_page(pages[i]);
+ SetPageUptodate(pages[i]);
+ }
+ }
+
+ for (i = 0; i < nr_pages; i++) {
+ unlock_page(pages[i]);
+ put_page(pages[i]);
+ }
+ }
+
+ kfree(pages);
+ return;
+
+skip_pages:
+ for (i = 0; i < nr_pages; i++) {
+ unlock_page(pages[i]);
+ put_page(pages[i]);
+ }
+ kfree(pages);
+}
+
+const struct address_space_operations squashfs_aops = {
+ .read_folio = squashfs_read_folio,
+ .readahead = squashfs_readahead
+};