On 06/28/2013 08:41 PM, 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? 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,
Looks Ext4 does the same thing to XFS in this case :), but OCFS2 does not. I'd like to write a test case for xfstest if we reach an agreement. 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
