On Mon, Apr 24, 2017 at 11:28 AM, Raghavendra Gowdappa <rgowdapp@xxxxxxxxxx> wrote:
Its a known issue in DHT. Since DHT relies on some bits (S+T) in the stat for identifying that a file is being migrated by a rebalance process, it strips them off. But the problem is if the same bits are being used by application (as in this case). The fix (if we can come up with one) might require some time for validation as impact can be large. Possible solutions are:
1. Pranith pointed out that rebalance process always holds an inodelk during file migration. Probably we can leverage this information and decide whether to strip the flags or not.
2. There is also a linkto xattr stored on the data-file during migration. Instead of unconditionally striping Phase1(2) flags, lookup/stat codepaths can check for the presence of this xattr too and strip the flags only if it is present. Note that with this solution application won't see the (S+T) bits in stat during rebalance.
Innocent question. If we have a linkto-xattr and the lock, do we need anything more to detect that migration is in progress? I am wondering if we can remove the reliance on S+T bits. Worst case we will have to store the info on the xattr.
regards,
Raghavendra.
----- Original Message -----
> From: "Pranith Kumar Karampuri" <pkarampu@xxxxxxxxxx>
> To: "qingwei wei" <tchengwee@xxxxxxxxx>
> Cc: "Gluster Devel" <gluster-devel@xxxxxxxxxxx>, "Raghavendra Gowdappa" <rgowdapp@xxxxxxxxxx>, "Nithya Balachandran"
> <nbalacha@xxxxxxxxxx>
> Sent: Monday, April 24, 2017 11:03:29 AM
> Subject: Re: fstest for fuse mount gluster
>
> This is a bug in dht it seems like. It is stripping PHASE1 flags
> unconditionally.
>
> (gdb)
> 1212 DHT_STRIP_PHASE1_FLAGS (&local->stbuf);
> (gdb) p local->stbuf.ia_prot
> $18 = {
> suid = 1 '\001',
> sgid = 1 '\001', <-------
> sticky = 1 '\001', <-------
> .........
> }
> (gdb) n
> 1213 dht_set_fixed_dir_stat (&local->postparent);
> (gdb) p local->stbuf.ia_prot
> $19 = {
> suid = 1 '\001',
> sgid = 0 '\000', <-------
> sticky = 0 '\000', <-------
> ...
>
> This is leading to 7777-->4777
>
> Will update bug with same info
>
>
> On Thu, Apr 20, 2017 at 8:58 PM, qingwei wei <tchengwee@xxxxxxxxx> wrote:
>
> > Hi,
> >
> > Posted this in gluster-user mailing list but got no response so far, so i
> > post in gluster-devel.
> >
> > I found this test suite (https://github.com/Hnasar/pjdfstest ) for me to
> > test fuse mount gluster and there is some reported issue from the test. One
> > of the error is as follow.
> >
> > When i chmod 7777 to a file in fuse mounted gluster volume. the return
> > stat value for the file is not 7777 instead of 4777.
> >
> > root@ubuntu16d:/mnt/g310mp# touch test
> > root@ubuntu16d:/mnt/g310mp# chmod 7777 test
> > root@ubuntu16d:/mnt/g310mp# stat test
> > File: 'test'
> > Size: 0 Blocks: 0 IO Block: 131072 regular empty
> > file
> > Device: 29h/41d Inode: 9618589997017543511 Links: 1
> > Access: (4777/-rwsrwxrwx) Uid: ( 0/ root) Gid: ( 0/ root)
> > Access: 2017-11-30 14:21:23.374871207 +0800
> > Modify: 2017-11-30 14:21:16.974871000 +0800
> > Change: 2017-11-30 14:21:23.374871207 +0800
> > Birth: -
> >
> > Performing this operation in normal ext4 system produce correct result.
> >
> > root@ubuntu16d:/mnt/g310mp# touch ~/testfile
> > root@ubuntu16d:/mnt/g310mp# chmod 7777 ~/testfile
> > root@ubuntu16d:/mnt/g310mp# stat ~/testfile
> > File: '/home/ubuntu/testfile'
> > Size: 0 Blocks: 0 IO Block: 4096 regular empty
> > file
> > Device: fc00h/64512d Inode: 662649 Links: 1
> > Access: (7777/-rwsrwsrwt) Uid: ( 0/ root) Gid: ( 0/ root)
> > Access: 2017-11-30 14:23:00.518867795 +0800
> > Modify: 2017-11-30 14:23:00.518867795 +0800
> > Change: 2017-11-30 14:23:08.742867507 +0800
> > Birth: -
> >
> > Besides 7777, 3777 also an issue. The stat return is 0777.
> >
> > My OS is Ubuntu 16.04 and my gluster version is 3.10.1 and the it is a
> > simple volume with default parameter.
> >
> > root@ubuntu16d:/mnt/g310mp# gluster volume info
> >
> > Volume Name: g310
> > Type: Distribute
> > Volume ID: 114666c6-4884-436a-81a8-2deb3c0923ba
> > Status: Started
> > Snapshot Count: 0
> > Number of Bricks: 1
> > Transport-type: tcp
> > Bricks:
> > Brick1: 192.168.36.130:/mnt/g310brick
> > Options Reconfigured:
> > transport.address-family: inet
> > nfs.disable: on
> >
> > for me, i seldom use those mode (3777 & 7777) but i cannot say for sure
> > for others. So is this something i should be concerned about?
> >
> > Cw
> >
> > _______________________________________________
> > Gluster-devel mailing list
> > Gluster-devel@xxxxxxxxxxx
> > http://lists.gluster.org/mailman/listinfo/gluster-devel
> >
>
>
>
> --
> Pranith
>
--
Pranith
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