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    Btrfs: fix assertion on fsync of regular file when using no-holes feature · 7ed586d0
    Filipe Manana authored
    When using the NO_HOLES feature and logging a regular file, we were
    expecting that if we find an inline extent, that either its size in RAM
    (uncompressed and unenconded) matches the size of the file or if it does
    not, that it matches the sector size and it represents compressed data.
    This assertion does not cover a case where the length of the inline extent
    is smaller than the sector size and also smaller the file's size, such
    case is possible through fallocate. Example:
      $ mkfs.btrfs -f -O no-holes /dev/sdb
      $ mount /dev/sdb /mnt
      $ xfs_io -f -c "pwrite -S 0xb60 0 21" /mnt/foobar
      $ xfs_io -c "falloc 40 40" /mnt/foobar
      $ xfs_io -c "fsync" /mnt/foobar
    In the above example we trigger the assertion because the inline extent's
    length is 21 bytes while the file size is 80 bytes. The fallocate() call
    merely updated the file's size and did not touch the existing inline
    extent, as expected.
    So fix this by adjusting the assertion so that an inline extent length
    smaller than the file size is valid if the file size is smaller than the
    filesystem's sector size.
    A test case for fstests follows soon.
    Reported-by: default avatarAnatoly Trosinenko <>
    Fixes: a89ca6f2 ("Btrfs: fix fsync after truncate when no_holes feature is enabled")
    CC: # 4.14+
    Signed-off-by: default avatarFilipe Manana <>
    Signed-off-by: default avatarDavid Sterba <>