Linux 3.17: Deal with d_splice_alias errors

In 3.17 the logic in d_splice_alias has changed.  Of interest to
us is the fact that it will now return an EIO error if it finds
an existing connected directory for the dentry, where it would
previously have added a new alias for it.  As a result the end
user can get EIO errors when accessing any file in a volume
if the volume was first accessed through a different path (ex:
RO path vs RW path).

This commit just restores the old behaviour, adding the directory
alias manually in the error case, which is what older versions
of d_splice_alias used to do.

Change-Id: I5558c64760e4cad2bd3dc648067d81020afc69b6
Reviewed-on: http://gerrit.openafs.org/11492
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Perry Ruiter <pruiter@sinenomine.net>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: D Brashear <shadow@your-file-system.com>

diff --git a/src/afs/LINUX/osi_vnodeops.c b/src/afs/LINUX/osi_vnodeops.c
index e03187f9db865ad19d7a86b4d2370b56c838c917..0cdd9e0d1abcb3e6883ecbdc060699e4b085ffde 100644 (file)
--- a/src/afs/LINUX/osi_vnodeops.c
+++ b/src/afs/LINUX/osi_vnodeops.c
@@ -1593,9 +1593,18 @@ afs_linux_lookup(struct inode *dip, struct dentry *dp)
     /* It's ok for the file to not be found. That's noted by the caller by
      * seeing that the dp->d_inode field is NULL.
      */
-    if (!code || code == ENOENT)
-       return newdp;
-    else 
+    if (!code || code == ENOENT) {
+       /*
+        * d_splice_alias can return an error (EIO) if there is an existing
+        * connected directory alias for this dentry.
+        */
+       if (!IS_ERR(newdp))
+           return newdp;
+       else {
+           d_add(dp, ip);
+           return NULL;
+       }
+    } else
        return ERR_PTR(afs_convert_code(code));
 }