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? Cheers, Dave. -- Dave Chinner da...@fromorbit.com -- 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
