[Bugs] [Bug 1258196] New: gNFSd: NFS mount fails with "Remote I/O error"

[bugzilla at redhat.com]

https://bugzilla.redhat.com/show_bug.cgi?id=1258196

            Bug ID: 1258196
           Summary: gNFSd: NFS mount fails with "Remote I/O error"
           Product: GlusterFS
           Version: mainline
         Component: nfs
          Keywords: Patch, Triaged
          Severity: medium
          Assignee: bugs at gluster.org
          Reporter: ndevos at redhat.com
                CC: bugs at gluster.org, gluster-bugs at redhat.com
            Blocks: 1258069



+++ This bug was initially created as a clone of Bug #1258069 +++

Description of problem:
gNFSd throws Remote IO error for mounts to directories which have changed OOB
from the target gNFSd (say from a FUSE mount).  Internally this is due to
ESTALE (op_errno == 116) being returned to mnt3_resolve_subdir_cbk, this causes
the code path to unroll with an error.  Per the AFR2 code comments, the correct
behavior is for gNFSd to purge the inode from it's inode table and do a fresh
lookup on the inode.

The question might follow why does mnt3_resolve_subdir_cbk get ESTALE?  This is
because the LOOKUP request is actually sent to the bricks via gfid vs a full
path lookup, and this optimization happens because the path successfully grep's
the gNFSd inode table for the GFID.  This isn't incorrect behavior, but is the
root cause of the ESTALE.

Version-Release number of selected component (if applicable):
v3.6.x (verified), probably 3.7.x but unverified.

How reproducible:
100%, see prove test.


Steps to Reproduce:
See prove test.

Actual results:
Mount returns with "Remote I/O error"

Expected results:
The mount should succeed.


Additional info:
See attached prove test and patch which resolves the bug.

--- Additional comment from  on 2015-08-28 22:57:54 CEST ---

Patch based off of FB GlusterFS v3.6.3, might not line up exactly but patching
mnt3_resolve_subdir_cbk of mounts3.c per this patch should do the trick.

--- Additional comment from  on 2015-08-29 00:37:58 CEST ---


Referenced Bugs:

https://bugzilla.redhat.com/show_bug.cgi?id=1258069
[Bug 1258069] gNFSd: NFS mount fails with "Remote I/O error"
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