Hey Xiubo,
On Wed, May 17, 2023 at 4:45 PM Xiubo Li xiubli@redhat.com wrote:
On 5/17/23 19:04, Xiubo Li wrote:
On 5/17/23 18:31, Ilya Dryomov wrote:
On Wed, May 17, 2023 at 7:24 AM xiubli@redhat.com wrote:
From: Xiubo Li xiubli@redhat.com
When the MClientSnap reqeust's op is not CEPH_SNAP_OP_SPLIT the request may still contain a list of 'split_realms', and we need to skip it anyway. Or it will be parsed as a corrupt snaptrace.
Cc: stable@vger.kernel.org Cc: Frank Schilder frans@dtu.dk Reported-by: Frank Schilder frans@dtu.dk URL: https://tracker.ceph.com/issues/61200 Signed-off-by: Xiubo Li xiubli@redhat.com
fs/ceph/snap.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index 0e59e95a96d9..d95dfe16b624 100644 --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -1114,6 +1114,9 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc, continue; adjust_snap_realm_parent(mdsc, child, realm->ino); }
} else {p += sizeof(u64) * num_split_inos;p += sizeof(u64) * num_split_realms; } /*-- 2.40.1
Hi Xiubo,
This code appears to be very old -- it goes back to the initial commit 963b61eb041e ("ceph: snapshot management") in 2009. Do you have an explanation for why this popped up only now?
As I remembered we hit this before in one cu BZ last year, but I couldn't remember exactly which one. But I am not sure whether @Jeff saw this before I joint ceph team.
@Venky,
Do you remember which one ? As I remembered this is why we fixed the snaptrace issue by blocking all the IOs and at the same time blocklisting the kclient before.
Before the kcleint won't dump the corrupted msg and we don't know what was wrong with the msg and also we added code to dump the msg in the above fix.
The "corrupted" snaptrace issue happened just after the mds asserted hitting the metadata corruption (dentry first corrupted) and it _seemed_ that this corruption somehow triggered a corrupted snaptrace to be sent to the client.
Thanks
- Xiubo
Has MDS always been including split_inos and split_realms arrays in !CEPH_SNAP_OP_SPLIT case or is this a recent change? If it's a recent change, I'd argue that this needs to be addressed on the MDS side.
While in MDS side for the _UPDATE op it won't send the 'split_realm' list just before the commit in 2017:
commit 93e7267757508520dfc22cff1ab20558bd4a44d4 Author: Yan, Zheng zyan@redhat.com Date: Fri Jul 21 21:40:46 2017 +0800
mds: send snap related messages centrally during mds recovery sending CEPH_SNAP_OP_SPLIT and CEPH_SNAP_OP_UPDATE messages to clients centrally in MDCache::open_snaprealms() Signed-off-by: "Yan, Zheng" <zyan@redhat.com>Before this commit it will only send the 'split_realm' list for the _SPLIT op.
The following the snaptrace:
[Wed May 10 16:03:06 2023] header: 00000000: 05 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [Wed May 10 16:03:06 2023] header: 00000010: 12 03 7f 00 01 00 00 01 00 00 00 00 00 00 00 00 ................ [Wed May 10 16:03:06 2023] header: 00000020: 00 00 00 00 02 01 00 00 00 00 00 00 00 01 00 00 ................ [Wed May 10 16:03:06 2023] header: 00000030: 00 98 0d 60 93 ...`. [Wed May 10 16:03:06 2023] front: 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ <<== The op is 0, which is 'CEPH_SNAP_OP_UPDATE' [Wed May 10 16:03:06 2023] front: 00000010: 0c 00 00 00 88 00 00 00 d1 c0 71 38 00 01 00 00 ..........q8.... <<== The '0c' is the split_realm number [Wed May 10 16:03:06 2023] front: 00000020: 22 c8 71 38 00 01 00 00 d7 c7 71 38 00 01 00 00 ".q8......q8.... <<== All the 'q8' are the ino# [Wed May 10 16:03:06 2023] front: 00000030: d9 c7 71 38 00 01 00 00 d4 c7 71 38 00 01 00 00 ..q8......q8.... [Wed May 10 16:03:06 2023] front: 00000040: f1 c0 71 38 00 01 00 00 d4 c0 71 38 00 01 00 00 ..q8......q8.... [Wed May 10 16:03:06 2023] front: 00000050: 20 c8 71 38 00 01 00 00 1d c8 71 38 00 01 00 00 .q8......q8.... [Wed May 10 16:03:06 2023] front: 00000060: ec c0 71 38 00 01 00 00 d6 c0 71 38 00 01 00 00 ..q8......q8.... [Wed May 10 16:03:06 2023] front: 00000070: ef c0 71 38 00 01 00 00 6a 11 2d 1a 00 01 00 00 ..q8....j.-..... [Wed May 10 16:03:06 2023] front: 00000080: 01 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 ................ [Wed May 10 16:03:06 2023] front: 00000090: ee 01 00 00 00 00 00 00 01 00 00 00 00 00 00 00 ................ [Wed May 10 16:03:06 2023] front: 000000a0: 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 ................ [Wed May 10 16:03:06 2023] front: 000000b0: 01 09 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [Wed May 10 16:03:06 2023] front: 000000c0: 01 00 00 00 00 00 00 00 02 09 00 00 00 00 00 00 ................ [Wed May 10 16:03:06 2023] front: 000000d0: 05 00 00 00 00 00 00 00 01 09 00 00 00 00 00 00 ................ [Wed May 10 16:03:06 2023] front: 000000e0: ff 08 00 00 00 00 00 00 fd 08 00 00 00 00 00 00 ................ [Wed May 10 16:03:06 2023] front: 000000f0: fb 08 00 00 00 00 00 00 f9 08 00 00 00 00 00 00 ................ [Wed May 10 16:03:06 2023] footer: 00000000: ca 39 06 07 00 00 00 00 00 00 00 00 42 06 63 61 .9..........B.ca [Wed May 10 16:03:06 2023] footer: 00000010: 7b 4b 5d 2d 05 {K]-.
And if the split_realm number equals to sizeof(ceph_mds_snap_realm) + extra snap buffer size by coincidence, the above 'corrupted' snaptrace will be parsed by kclient too and kclient won't give any warning, but it will corrupted the snaprealm and capsnap info in kclient.
Thanks
- Xiubo
Thanks,
Ilya