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    Subject[PATCH 3.16 088/366] ext4: fix fencepost error in check for inode count overflow during resize
    3.16.61-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Jan Kara <jack@suse.cz>

    commit 4f2f76f751433908364ccff82f437a57d0e6e9b7 upstream.

    ext4_resize_fs() has an off-by-one bug when checking whether growing of
    a filesystem will not overflow inode count. As a result it allows a
    filesystem with 8192 inodes per group to grow to 64TB which overflows
    inode count to 0 and makes filesystem unusable. Fix it.

    Fixes: 3f8a6411fbada1fa482276591e037f3b1adcf55b
    Reported-by: Jaco Kroon <jaco@uls.co.za>
    Signed-off-by: Jan Kara <jack@suse.cz>
    Signed-off-by: Theodore Ts'o <tytso@mit.edu>
    Reviewed-by: Andreas Dilger <adilger@dilger.ca>
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    fs/ext4/resize.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/fs/ext4/resize.c
    +++ b/fs/ext4/resize.c
    @@ -1906,7 +1906,7 @@ retry:
    return 0;

    n_group = ext4_get_group_number(sb, n_blocks_count - 1);
    - if (n_group > (0xFFFFFFFFUL / EXT4_INODES_PER_GROUP(sb))) {
    + if (n_group >= (0xFFFFFFFFUL / EXT4_INODES_PER_GROUP(sb))) {
    ext4_warning(sb, "resize would cause inodes_count overflow");
    return -EINVAL;
    }
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