> commit 3912e7b44cf77e9452d4d0cb6c1da9c7043bb7f1
> Author: Theodore Ts'o <tytso@xxxxxxx>
> Date: Fri Oct 6 23:09:55 2017 -0400
>
> ext4: fix interaction between i_size, fallocate, and delalloc after a crash
>
> If there are pending writes subject to delayed allocation, then i_size
> will show size after the writes have completed, while i_disksize
> contains the value of i_size on the disk (since the writes have not
> been persisted to disk).
>
> If fallocate(2) is called with the FALLOC_FL_KEEP_SIZE flag, either
> with or without the FALLOC_FL_ZERO_RANGE flag set, and the new size
> after the fallocate(2) is between i_size and i_disksize, then after a
> crash, if a journal commit has resulted in the changes made by the
> fallocate() call to be persisted after a crash, but the delayed
> allocation write has not resolved itself, i_size would not be updated,
> and this would cause the following e2fsck complaint:
>
> Inode 12, end of extent exceeds allowed value
> (logical block 33, physical block 33441, len 7)
>
> This can only take place on a sparse file, where the fallocate(2) call
> is allocating blocks in a range which is before a pending delayed
> allocation write which is extending i_size. Since this situation is
> quite rare, and the window in which the crash must take place is
> typically < 30 seconds, in practice this condition will rarely happen.
>
> Nevertheless, it can be triggered in testing, and in particular by
> xfstests generic/456.
>
> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
> Reported-by: Amir Goldstein <amir73il@xxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
The patch looks good to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 97f0fd06728d..07bca11749d4 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4794,7 +4794,8 @@ static long ext4_zero_range(struct file *file, loff_t offset,
> }
>
> if (!(mode & FALLOC_FL_KEEP_SIZE) &&
> - offset + len > i_size_read(inode)) {
> + (offset + len > i_size_read(inode) ||
> + offset + len > EXT4_I(inode)->i_disksize)) {
> new_size = offset + len;
> ret = inode_newsize_ok(inode, new_size);
> if (ret)
> @@ -4965,7 +4966,8 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
> }
>
> if (!(mode & FALLOC_FL_KEEP_SIZE) &&
> - offset + len > i_size_read(inode)) {
> + (offset + len > i_size_read(inode) ||
> + offset + len > EXT4_I(inode)->i_disksize)) {
> new_size = offset + len;
> ret = inode_newsize_ok(inode, new_size);
> if (ret)
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
