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Diffstat (limited to 'fs/btrfs/extent_io.c')
-rw-r--r--fs/btrfs/extent_io.c80
1 files changed, 66 insertions, 14 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index c32d226bfecc..885f533a34d9 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2795,7 +2795,8 @@ static int submit_extent_page(int rw, struct extent_io_tree *tree,
bio_end_io_t end_io_func,
int mirror_num,
unsigned long prev_bio_flags,
- unsigned long bio_flags)
+ unsigned long bio_flags,
+ bool force_bio_submit)
{
int ret = 0;
struct bio *bio;
@@ -2813,6 +2814,7 @@ static int submit_extent_page(int rw, struct extent_io_tree *tree,
contig = bio_end_sector(bio) == sector;
if (prev_bio_flags != bio_flags || !contig ||
+ force_bio_submit ||
merge_bio(rw, tree, page, offset, page_size, bio, bio_flags) ||
bio_add_page(bio, page, page_size, offset) < page_size) {
ret = submit_one_bio(rw, bio, mirror_num,
@@ -2906,7 +2908,8 @@ static int __do_readpage(struct extent_io_tree *tree,
get_extent_t *get_extent,
struct extent_map **em_cached,
struct bio **bio, int mirror_num,
- unsigned long *bio_flags, int rw)
+ unsigned long *bio_flags, int rw,
+ u64 *prev_em_start)
{
struct inode *inode = page->mapping->host;
u64 start = page_offset(page);
@@ -2954,6 +2957,7 @@ static int __do_readpage(struct extent_io_tree *tree,
}
while (cur <= end) {
unsigned long pnr = (last_byte >> PAGE_CACHE_SHIFT) + 1;
+ bool force_bio_submit = false;
if (cur >= last_byte) {
char *userpage;
@@ -3004,6 +3008,49 @@ static int __do_readpage(struct extent_io_tree *tree,
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
+ * 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->orig_start)
+ force_bio_submit = true;
+
+ if (prev_em_start)
+ *prev_em_start = em->orig_start;
+
free_extent_map(em);
em = NULL;
@@ -3053,7 +3100,8 @@ static int __do_readpage(struct extent_io_tree *tree,
bdev, bio, pnr,
end_bio_extent_readpage, mirror_num,
*bio_flags,
- this_bio_flag);
+ this_bio_flag,
+ force_bio_submit);
if (!ret) {
nr++;
*bio_flags = this_bio_flag;
@@ -3080,7 +3128,8 @@ static inline void __do_contiguous_readpages(struct extent_io_tree *tree,
get_extent_t *get_extent,
struct extent_map **em_cached,
struct bio **bio, int mirror_num,
- unsigned long *bio_flags, int rw)
+ unsigned long *bio_flags, int rw,
+ u64 *prev_em_start)
{
struct inode *inode;
struct btrfs_ordered_extent *ordered;
@@ -3100,7 +3149,7 @@ static inline void __do_contiguous_readpages(struct extent_io_tree *tree,
for (index = 0; index < nr_pages; index++) {
__do_readpage(tree, pages[index], get_extent, em_cached, bio,
- mirror_num, bio_flags, rw);
+ mirror_num, bio_flags, rw, prev_em_start);
page_cache_release(pages[index]);
}
}
@@ -3110,7 +3159,8 @@ static void __extent_readpages(struct extent_io_tree *tree,
int nr_pages, get_extent_t *get_extent,
struct extent_map **em_cached,
struct bio **bio, int mirror_num,
- unsigned long *bio_flags, int rw)
+ unsigned long *bio_flags, int rw,
+ u64 *prev_em_start)
{
u64 start = 0;
u64 end = 0;
@@ -3131,7 +3181,7 @@ static void __extent_readpages(struct extent_io_tree *tree,
index - first_index, start,
end, get_extent, em_cached,
bio, mirror_num, bio_flags,
- rw);
+ rw, prev_em_start);
start = page_start;
end = start + PAGE_CACHE_SIZE - 1;
first_index = index;
@@ -3142,7 +3192,8 @@ static void __extent_readpages(struct extent_io_tree *tree,
__do_contiguous_readpages(tree, &pages[first_index],
index - first_index, start,
end, get_extent, em_cached, bio,
- mirror_num, bio_flags, rw);
+ mirror_num, bio_flags, rw,
+ prev_em_start);
}
static int __extent_read_full_page(struct extent_io_tree *tree,
@@ -3168,7 +3219,7 @@ static int __extent_read_full_page(struct extent_io_tree *tree,
}
ret = __do_readpage(tree, page, get_extent, NULL, bio, mirror_num,
- bio_flags, rw);
+ bio_flags, rw, NULL);
return ret;
}
@@ -3194,7 +3245,7 @@ int extent_read_full_page_nolock(struct extent_io_tree *tree, struct page *page,
int ret;
ret = __do_readpage(tree, page, get_extent, NULL, &bio, mirror_num,
- &bio_flags, READ);
+ &bio_flags, READ, NULL);
if (bio)
ret = submit_one_bio(READ, bio, mirror_num, bio_flags);
return ret;
@@ -3447,7 +3498,7 @@ static noinline_for_stack int __extent_writepage_io(struct inode *inode,
sector, iosize, pg_offset,
bdev, &epd->bio, max_nr,
end_bio_extent_writepage,
- 0, 0, 0);
+ 0, 0, 0, false);
if (ret)
SetPageError(page);
}
@@ -3749,7 +3800,7 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
ret = submit_extent_page(rw, tree, p, offset >> 9,
PAGE_CACHE_SIZE, 0, bdev, &epd->bio,
-1, end_bio_extent_buffer_writepage,
- 0, epd->bio_flags, bio_flags);
+ 0, epd->bio_flags, bio_flags, false);
epd->bio_flags = bio_flags;
if (ret) {
set_btree_ioerr(p);
@@ -4153,6 +4204,7 @@ int extent_readpages(struct extent_io_tree *tree,
struct page *page;
struct extent_map *em_cached = NULL;
int nr = 0;
+ u64 prev_em_start = (u64)-1;
for (page_idx = 0; page_idx < nr_pages; page_idx++) {
page = list_entry(pages->prev, struct page, lru);
@@ -4169,12 +4221,12 @@ int extent_readpages(struct extent_io_tree *tree,
if (nr < ARRAY_SIZE(pagepool))
continue;
__extent_readpages(tree, pagepool, nr, get_extent, &em_cached,
- &bio, 0, &bio_flags, READ);
+ &bio, 0, &bio_flags, READ, &prev_em_start);
nr = 0;
}
if (nr)
__extent_readpages(tree, pagepool, nr, get_extent, &em_cached,
- &bio, 0, &bio_flags, READ);
+ &bio, 0, &bio_flags, READ, &prev_em_start);
if (em_cached)
free_extent_map(em_cached);
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-24 07:52:01 +0000