diff options
| author | David Howells <dhowells@redhat.com> | 2024-07-18 20:19:32 +0100 |
|---|---|---|
| committer | Steve French <stfrench@microsoft.com> | 2024-07-19 11:08:57 -0500 |
| commit | de40579b903883274fe203865f29d66b168b7236 (patch) | |
| tree | d796419b21a084acda7a717aa1fcf66748979584 /fs/smb | |
| parent | ae4ccca47195332c69176b8615c5ee17efd30c46 (diff) | |
cifs: Fix server re-repick on subrequest retry
When a subrequest is marked for needing retry, netfs will call
cifs_prepare_write() which will make cifs repick the server for the op
before renegotiating credits; it then calls cifs_issue_write() which
invokes smb2_async_writev() - which re-repicks the server.
If a different server is then selected, this causes the increment of
server->in_flight to happen against one record and the decrement to happen
against another, leading to misaccounting.
Fix this by just removing the repick code in smb2_async_writev(). As this
is only called from netfslib-driven code, cifs_prepare_write() should
always have been called first, and so server should never be NULL and the
preparatory step is repeated in the event that we do a retry.
The problem manifests as a warning looking something like:
WARNING: CPU: 4 PID: 72896 at fs/smb/client/smb2ops.c:97 smb2_add_credits+0x3f0/0x9e0 [cifs]
...
RIP: 0010:smb2_add_credits+0x3f0/0x9e0 [cifs]
...
smb2_writev_callback+0x334/0x560 [cifs]
cifs_demultiplex_thread+0x77a/0x11b0 [cifs]
kthread+0x187/0x1d0
ret_from_fork+0x34/0x60
ret_from_fork_asm+0x1a/0x30
Which may be triggered by a number of different xfstests running against an
Azure server in multichannel mode. generic/249 seems the most repeatable,
but generic/215, generic/249 and generic/308 may also show it.
Fixes: 3ee1a1fc3981 ("cifs: Cut over to using netfslib")
Cc: stable@vger.kernel.org
Reported-by: Steve French <smfrench@gmail.com>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Acked-by: Tom Talpey <tom@talpey.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Aurelien Aptel <aaptel@suse.com>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs/smb')
| -rw-r--r-- | fs/smb/client/smb2pdu.c | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c index 2ae2dbb6202b..bb84a89e5905 100644 --- a/fs/smb/client/smb2pdu.c +++ b/fs/smb/client/smb2pdu.c @@ -4859,9 +4859,6 @@ smb2_async_writev(struct cifs_io_subrequest *wdata) struct cifs_io_parms *io_parms = NULL; int credit_request; - if (!wdata->server || test_bit(NETFS_SREQ_RETRYING, &wdata->subreq.flags)) - server = wdata->server = cifs_pick_channel(tcon->ses); - /* * in future we may get cifs_io_parms passed in from the caller, * but for now we construct it here... |