• Dmitri Monakhov's avatar
    fs: truncate blocks outside i_size after O_DIRECT write error · 0f64415d
    Dmitri Monakhov authored
    In case of error extending write may have instantiated a few blocks
    outside i_size.  We need to trim these blocks.  We have to do it
    *regardless* to blocksize.  At least ext2, ext3 and reiserfs interpret
    (i_size < biggest block) condition as error.  Fsck will complain about
    wrong i_size.  Then fsck will fix the error by changing i_size according
    to the biggest block.  This is bad because this blocks contain garbage
    from previous write attempt.  And result in data corruption.
    $touch /mnt/test/BIG_FILE
    ## at this moment /mnt/test/BIG_FILE size and blocks equal to zero
    open("/mnt/test/BIG_FILE", O_WRONLY|O_CREAT|O_DIRECT, 0666) = 3
    write(3, "aaaaaaaaaaaa"..., 104857600) = -1 ENOSPC (No space left on device)
    ## size and block sould't be changed because write op failed.
    $stat /mnt/test/BIG_FILE
    File: `/mnt/test/BIG_FILE'
    Size: 0 Blocks: 110896 IO Block: 1024 regular empty file
    <<<<<<<<^^^^^^^^^^^^^^^^^^^^^^^^^^^^^file size is less than biggest block idx
    Device: fe07h/65031d Inode: 14 Links: 1
    Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
    Access: 2007-01-24 20:03:38.000000000 +0300
    Modify: 2007-01-24 20:03:38.000000000 +0300
    Change: 2007-01-24 20:03:39.000000000 +0300
    #fsck.ext3 -f /dev/VG/test
    e2fsck 1.39 (29-May-2006)
    Pass 1: Checking inodes, blocks, and sizes
    Inode 14, i_size is 0, should be 56556544. Fix<y>? yes
    Pass 2: Checking directory structure
    #####TESTCASE_ENDdiff --git a/fs/direct-io.c b/fs/direct-io.c
    index af0558d..4e88bea 100644
    [akpm@linux-foundation.org: use i_size_read()]
    Signed-off-by: default avatarDmitri Monakhov <dmonakhov@openvz.org>
    Cc: Zach Brown <zach.brown@oracle.com>
    Cc: Nick Piggin <npiggin@suse.de>
    Cc: Badari Pulavarty <pbadari@us.ibm.com>
    Cc: Chris Mason <chris.mason@oracle.com>
    Cc: Dave Chinner <david@fromorbit.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
direct-io.c 34.4 KB