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Btrfs: Fix csum error for compressed data 

The decompress code doesn't take the logical offset in extent
pointer into account. If the logical offset isn't zero, data
will be decompressed into wrong pages.

The solution used here is to record the starting offset of the extent
in the file separately from the logical start of the extent_map struct.
This allows us to avoid problems inserting overlapping extents.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This commit is contained in:
Yan Zheng 2008-11-10 07:34:43 -05:00 committed by Chris Mason
parent f2b1c41cf9
commit ff5b7ee33d
4 changed files with 8 additions and 4 deletions
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6
fs/btrfs/compression.c
View File

@ -505,7 +505,6 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
struct block_device *bdev;
struct bio *comp_bio;
u64 cur_disk_byte = (u64)bio->bi_sector << 9;
u64 em_len;
struct extent_map *em;
int ret;
@ -524,9 +523,8 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
cb->errors = 0;
cb->inode = inode;
cb->start = em->start;
cb->start = em->orig_start;
compressed_len = em->block_len;
em_len = em->len;
free_extent_map(em);
cb->len = uncompressed_len;
@ -545,7 +543,7 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
}
cb->nr_pages = nr_pages;
add_ra_bio_pages(inode, cb->start + em_len, cb);
add_ra_bio_pages(inode, em->start + em->len, cb);
if (!btrfs_test_opt(root, NODATASUM) &&
!btrfs_test_flag(inode, NODATASUM)) {

1
fs/btrfs/extent_map.h
View File

@ -20,6 +20,7 @@ struct extent_map {
/* all of these are in bytes */
u64 start;
u64 len;
u64 orig_start;
u64 block_start;
u64 block_len;
unsigned long flags;

2
fs/btrfs/file.c
View File

@ -222,6 +222,7 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
em->start < start) {
split->start = em->start;
split->len = start - em->start;
split->orig_start = em->orig_start;
split->block_start = em->block_start;
if (compressed)
@ -243,6 +244,7 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
split->start = start + len;
split->len = em->start + em->len - (start + len);
split->orig_start = em->orig_start;
split->bdev = em->bdev;
split->flags = flags;

3
fs/btrfs/inode.c
View File

@ -3949,6 +3949,8 @@ again:
found_type == BTRFS_FILE_EXTENT_PREALLOC) {
em->start = extent_start;
em->len = extent_end - extent_start;
em->orig_start = extent_start -
btrfs_file_extent_offset(leaf, item);
bytenr = btrfs_file_extent_disk_bytenr(leaf, item);
if (bytenr == 0) {
em->block_start = EXTENT_MAP_HOLE;
@ -3988,6 +3990,7 @@ again:
em->start = extent_start + extent_offset;
em->len = (copy_size + root->sectorsize - 1) &
~((u64)root->sectorsize - 1);
em->orig_start = EXTENT_MAP_INLINE;
if (compressed)
set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
ptr = btrfs_file_extent_inline_start(item) + extent_offset;