On 01/07/2014 09:11 AM, Tsutomu Itoh wrote: > On 2014/01/06 17:48, Wang Shilong wrote: >> Itoh San, >> >> On 01/06/2014 04:23 PM, Tsutomu Itoh wrote: >>> On 2014/01/06 17:08, Wang Shilong wrote: >>>> Here we expect 0 as return value, fix it. >>>> >>>> Signed-off-by: Wang Shilong <wangsl.fnst@xxxxxxxxxxxxxx> >>>> Cc: Josef Bacik <jbacik@xxxxxx> >>>> --- >>>> tests/btrfs/022 | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> mode change 100644 => 100755 tests/btrfs/022 >>>> >>>> diff --git a/tests/btrfs/022 b/tests/btrfs/022 >>>> old mode 100644 >>>> new mode 100755 >>>> index 5b18643..142aaf9 >>>> --- a/tests/btrfs/022 >>>> +++ b/tests/btrfs/022 >>>> @@ -106,7 +106,7 @@ _limit_test() >>>> [ $? -ne 0 ] || _fail "quota should have limited us" >>>> dd if=/dev/urandom of=$SCRATCH_MNT/a/file bs=4M count=1 >> \ >>>> $seqres.full 2>&1 >>>> - [ $? -eq 0 ] || _fail "should have been allowed to write" >>>> + [ $? -ne 0 ] || _fail "should have been allowed to write" >>> from "man bash", >>> An OR list has the form >>> command1 || command2 >>> command2 is executed if and only if command1 returns a non-zero exit >>> status. >>> >>> So, original code is OK, I think. >> You are absolutely right, during my test i found we fail this case. >> I took a careful think about this: >> >> The problem is that we should clear the data we have written before, >> Because we may write some data before, for example we limit subvolume to 5M >> then we try this: >> >> # dd if=/dev/zero of=/mnt/data bs=10M count=1 >> >> Although we try to write 10M once, in kernel, we may split it into >> several request, >> at the end, we can still write some data actually, you can try the >> following command >> after the above command. >> >> # du -sh /mnt/data >> >> Here i think the best way to fix this problem is we disable quota and >> retry with 4m. > Umm... I don't think so. > Writing (or truncating) succeeds if sync is executed before writing 4MB. > Therefore, I think that there are some problems in quota. Itoh-San, The problem is that 'btrfs filesystem sync' will flush and commit transaction which will release some space, and this may give us enough space to reserve metadata space to truncate/remove file. For the below example: # dd if=/dev/zero of=/mnt/data bs=10M count=1 # sync # btrfs qgroup show /mnt qgroupid rfer excl -------- ---- ---- 0/5 5177344 5177344 Limit is 5M which means we still leave 65536 bytes space(4 leafsize). If you try: # rm -f /mnt/data It must fail, because, unlink a file will first try to reserve 5 nodesize(see __unlink_start_trans()) Let's see why truncate can succeed! # btrfs-debug-tree /dev/sda fs tree key (FS_TREE ROOT_ITEM 0) leaf 29966336 items 7 free space 15641 generation 11 owner 5 fs uuid 2b854d8d-710c-43c5-a6d5-0cb8b6b232ea chunk uuid 9b65e155-33b3-44d3-a413-bbc97af700a7 item 0 key (256 INODE_ITEM 0) itemoff 16123 itemsize 160 inode generation 3 transid 11 size 8 block group 0 mode 40755 links 1 item 1 key (256 INODE_REF 256) itemoff 16111 itemsize 12 inode ref index 0 namelen 2 name: .. item 2 key (256 DIR_ITEM 2355243158) itemoff 16077 itemsize 34 location key (259 INODE_ITEM 0) type FILE namelen 4 datalen 0 name: data item 3 key (256 DIR_INDEX 4) itemoff 16043 itemsize 34 location key (259 INODE_ITEM 0) type FILE namelen 4 datalen 0 name: data item 4 key (259 INODE_ITEM 0) itemoff 15883 itemsize 160 inode generation 11 transid 11 size 5160960 block group 0 mode 100644 links 1 item 5 key (259 INODE_REF 256) itemoff 15869 itemsize 14 inode ref index 4 namelen 4 name: data item 6 key (259 EXTENT_DATA 0) itemoff 15816 itemsize 53 extent data disk byte 12713984 nr 5160960 extent data offset 0 nr 5160960 ram 5160960 extent compression 0 For truncating inode, we will reserve 2 leafsize every time and and then free qgroup reserved space in btrfs_end_transaction(), however, for this case, we only do one loop. So command 'truncate -s 0 /mnt/data' should return successfully. Please correct me if i miss something here ^_^ Thanks, Wang > > =============================================================== > > # mkfs.btrfs -f /dev/sdc2 > > WARNING! - Btrfs v3.12 IS EXPERIMENTAL > WARNING! - see http://btrfs.wiki.kernel.org before using > > Turning ON incompat feature 'extref': increased hardlink limit per file to 65536 > fs created label (null) on /dev/sdc2 > nodesize 16384 leafsize 16384 sectorsize 4096 size 9.31GiB > Btrfs v3.12 > # mount /dev/sdc2 /test8 > # btrfs quota enable /test8 > # btrfs qgroup limit 5M /test8 > # dd if=/dev/zero of=/test8/file1 bs=10M count=1 > dd: error writing '/test8/file1': Disk quota exceeded > 1+0 records in > 0+0 records out > 5160960 bytes (5.2 MB) copied, 0.012274 s, 420 MB/s > # ls -ls /test8/file1 > 5040 -rw-r--r-- 1 root root 5160960 Jan 7 09:54 /test8/file1 > # truncate -s 0 /test8/file1 > truncate: failed to truncate '/test8/file1' at 0 bytes: Disk quota exceeded > # ls -ls /test8/file1 > 5040 -rw-r--r-- 1 root root 5160960 Jan 7 09:54 /test8/file1 > # dd if=/dev/zero of=/test8/file1 bs=4M count=1 > dd: failed to open '/test8/file1': Disk quota exceeded > # ls -ls /test8/file1 > 5040 -rw-r--r-- 1 root root 5160960 Jan 7 09:54 /test8/file1 > # > > --------------------------------------------------------------- > > # mkfs.btrfs -f /dev/sdc2 > > WARNING! - Btrfs v3.12 IS EXPERIMENTAL > WARNING! - see http://btrfs.wiki.kernel.org before using > > Turning ON incompat feature 'extref': increased hardlink limit per file to 65536 > fs created label (null) on /dev/sdc2 > nodesize 16384 leafsize 16384 sectorsize 4096 size 9.31GiB > Btrfs v3.12 > # mount /dev/sdc2 /test8 > # btrfs quota enable /test8 > # btrfs qgroup limit 5M /test8 > # dd if=/dev/zero of=/test8/file1 bs=10M count=1 > dd: error writing '/test8/file1': Disk quota exceeded > 1+0 records in > 0+0 records out > 5160960 bytes (5.2 MB) copied, 0.0120232 s, 429 MB/s > # ls -ls /test8/file1 > 5040 -rw-r--r-- 1 root root 5160960 Jan 7 09:54 /test8/file1 > # btrfs filesystem sync /test8 > FSSync '/test8' > # truncate -s 0 /test8/file1 > # ls -ls /test8/file1 > 0 -rw-r--r-- 1 root root 0 Jan 7 09:54 /test8/file1 > # dd if=/dev/zero of=/test8/file1 bs=4M count=1 > 1+0 records in > 1+0 records out > 4194304 bytes (4.2 MB) copied, 0.00734557 s, 571 MB/s > # ls -ls /test8/file1 > 4096 -rw-r--r-- 1 root root 4194304 Jan 7 09:54 /test8/file1 > # > > =============================================================== > > Thanks, > Tsutomu > >> # btrfs qgroup limit none /mnt <------------- in case we are nearly full >> and we can not delete file. >> # rm -rf /mnt/data && btrfs filesystem sync /mnt >> # btrfs qgroup limit 5m /mnt >> # dd if=/dev/zero of=/mnt bs=4m count=1 >> >> Please correct me if i miss something here.^_^ >> >> Thanks, >> Wang >>> Thanks, >>> Tsutomu >>> >>>> } >>>> >>>> _scratch_mkfs > /dev/null 2>&1 >>>> > > -- > 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 > _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
