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.

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>
(cherry picked from commit 5815ee92a41cdcf105741d834042a5617dc4c219)

Change-Id: Ie86009ede93255c85fcf640af14c598fe1e42ca9
Reviewed-on: http://gerrit.openafs.org/11550
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>

diff --git a/src/afs/LINUX/osi_vnodeops.c b/src/afs/LINUX/osi_vnodeops.c
index 7e5cdd1e7cbcc59d75bf66dccc94d623a8ab7ad8..3ddcf422a70f22eecdf4127ff23d6d110d20cc42 100644 (file)
--- a/src/afs/LINUX/osi_vnodeops.c
+++ b/src/afs/LINUX/osi_vnodeops.c
@@ -1529,9 +1529,18 @@ 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));
 }