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>

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 7397c622fb6a14d4e691f432bc619f1fc0a52e75..8e7a78acf81af424185dc591967cc3f0db730c15 100644 (file)
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -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)) {

diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index accfedaeb51373fef185be74ae98e372f4c0e4e5..fb6eeef06bb0a88abcf9297c2c6d9156a35af552 100644 (file)
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -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;

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 337221ecca27ea2e05d4d9351a5e1dda8463ff30..85841c53880571fec4852364725e91b5a6eaef07 100644 (file)
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -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;
 

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index e01c0d0310abd3bc503c99944748ceb41db98965..59660293d29174a749fe162c2fd5703aae7d4e66 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -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;