On Thu, Jan 18, 2018 at 11:34:20AM +0000, fdmanana@xxxxxxxxxx wrote: > From: Filipe Manana <fdmanana@xxxxxxxx> > > For a fallocate's zero range operation that targets a range with an end > that is not aligned to the sector size, we can end up not updating the > inode's i_size. This happens when the last page of the range maps to an > unwritten (prealloc) extent and before that last page we have either a > hole or a written extent. This is because in this scenario we relied > on a call to btrfs_prealloc_file_range() to update the inode's i_size, > however it can only update the i_size to the "down aligned" end of the > range. > > Example: > > $ mkfs.btrfs -f /dev/sdc > $ mount /dev/sdc /mnt > $ xfs_io -f -c "pwrite -S 0xff 0 428K" /mnt/foobar > $ xfs_io -c "falloc -k 428K 4K" /mnt/foobar > $ xfs_io -c "fzero 0 430K" /mnt/foobar > $ du --bytes /mnt/foobar > 438272 /mnt/foobar > > The inode's i_size was left as 428Kb (438272 bytes) when it should have > been updated to 430Kb (440320 bytes). > Fix this by always updating the inode's i_size explicitly after zeroing > the range. > > Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx> Added to 4.16 queue, thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
