lkml.org 
[lkml]   [2007]   [Aug]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH] mm: fix blkdev size calculation in generic_write_checks
    Currently block device size calculated regardless its
    bd_block_size. This may result attempt to write outside
    block device if i_size not aligned to bdev->bd_block_size
    and result in EIO.

    #### TEST_CASE_BEGIN
    # fdisk -l /dev/sdc
    Disk /dev/sdc: 36.7 GB, 36703918080 bytes
    255 heads, 63 sectors/track, 4462 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes

    Device Boot Start End Blocks Id System
    /dev/sdc1 * 1 254 2040223+ 83 Ldinux
    /dev/sdc2 255 379 1004062+ 83 Linux
    ####
    #### /dev/sdc2 size not aligned to 4K

    #### at this time bd_block_size == 512 so generic_write_check
    #### performed correctly
    # dd if=/dev/zero of=/dev/sdc2 bs=1k count=7 seek=1004058
    dd: writing `/dev/sdc2': No space left on device
    5+0 records in
    4+0 records out

    #### this bdev contain ext4fs with blksize = 4K
    # mount /dev/sdc2 /mnt/
    #### after we mounted this bdev bd_block_size == fsblksize == 4K

    #### the same write operation failed with EIO
    # dd if=/dev/zero of=/dev/sdc2 bs=1k count=7 seek=1004058
    dd: writing `/dev/sdc2': Input/output error
    3+0 records in
    2+0 records out
    #### Attempt to write whole fsblock result write access outside
    #### blkdevice and cause -EIO (returned by blkdev_get_block)
    #### TEST_CASE_END

    Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
    ---
    mm/filemap.c | 4 +++-
    1 files changed, 3 insertions(+), 1 deletions(-)

    diff --git a/mm/filemap.c b/mm/filemap.c
    index 2c8776b..a23ee8a 100644
    --- a/mm/filemap.c
    +++ b/mm/filemap.c
    @@ -1867,9 +1867,11 @@ inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, i
    } else {
    #ifdef CONFIG_BLOCK
    loff_t isize;
    + unsigned int blksize;
    if (bdev_read_only(I_BDEV(inode)))
    return -EPERM;
    - isize = i_size_read(inode);
    + blksize = block_size(I_BDEV(inode));
    + isize = i_size_read(inode) & ~(blksize - 1);
    if (*pos >= isize) {
    if (*count || *pos > isize)
    return -ENOSPC;
    --
    1.5.2.2

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-08-15 15:55    [W:0.024 / U:0.212 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site