On 06/29/2013 10:22 AM, Dave Chinner wrote: > On Fri, Jun 28, 2013 at 08:41:00AM -0400, Josef Bacik wrote: >> On Fri, Jun 28, 2013 at 01:15:52PM +0800, Jeff Liu wrote: >>> From: Jie Liu <jeff....@oracle.com> >>> >>> Create a small file and fallocate it to a big size with >>> FALLOC_FL_KEEP_SIZE option, then truncate it back to the >>> small size again, the disk free space is not changed back >>> in this case. i.e, >>> >>> # dd if=/dev/zero of=/mnt/test bs=512 count=1 >>> # ls -l /mnt >>> total 4 >>> -rw-r--r-- 1 root root 512 Jun 28 11:35 test >>> >>> # df -h >>> Filesystem Size Used Avail Use% Mounted on >>> .... >>> /dev/sdb1 8.0G 56K 7.2G 1% /mnt >>> >>> # xfs_io -c 'falloc -k 512 5G' /mnt/test >>> # ls -l /mnt/test >>> -rw-r--r-- 1 root root 512 Jun 28 11:35 /mnt/test >>> >>> # sync; df -h >>> Filesystem Size Used Avail Use% Mounted on >>> .... >>> /dev/sdb1 8.0G 5.1G 2.2G 70% /mnt >>> >>> # xfs_io -c 'truncate 512' /mnt/test >>> # sync; df -h >>> Filesystem Size Used Avail Use% Mounted on >>> .... >>> /dev/sdb1 8.0G 5.1G 2.2G 70% /mnt >>> >>> With this fix, the truncated up space is back as: >>> # sync; df -h >>> Filesystem Size Used Avail Use% Mounted on >>> .... >>> /dev/sdb1 8.0G 56K 7.2G 1% /mnt >>> >>> Signed-off-by: Jie Liu <jeff....@oracle.com> >>> --- >>> fs/btrfs/inode.c | 3 --- >>> 1 file changed, 3 deletions(-) >>> >>> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c >>> index 4f9d16b..7e1a5ff 100644 >>> --- a/fs/btrfs/inode.c >>> +++ b/fs/btrfs/inode.c >>> @@ -4509,9 +4509,6 @@ static int btrfs_setsize(struct inode *inode, struct >>> iattr *attr) >>> int mask = attr->ia_valid; >>> int ret; >>> >>> - if (newsize == oldsize) >>> - return 0; >>> - >>> /* >>> * The regular truncate() case without ATTR_CTIME and ATTR_MTIME is a >>> * special case where we need to update the times despite not having >> >> Cc'ing a few people on this since I'd like their opinion. Looking at other >> fs's >> it looks like ext4 does the same thing we do and would leave the prealloc'ed >> space, but it appears that xfs will truncate it. What do we think is the >> correct behavior? > > XFS has had this truncate behaviour since at least the start of the > git tree history (2005). Given that these fallocate() > prealloc-blocks-beyond-EOF behaviours are modelled on what XFS has > historically provided, I think y'all can see what i think should be > done... > >> I'm inclined to take this patch, but I'd like to have an >> xfstest made for it so other file systems can be made to be consistent, and >> I'd >> like to make sure we all agree what is the correct behavior before we wander >> down that road. Thanks, > > I couldn't have said it better myself. Jeff, can you take care of > this, please?
Yes, I'll take care of this. Thanks, -Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
