libgfapi: send explicit lookups on inodes linked in readdirp

          Backport of http://review.gluster.org/11236

If the inode is linked via readdirp, then the consuners of gfapi which are using
handles (got either in lookup or readdirp) might not send an explicit lookup on
that object again (ex: NFS, samba, USS). If there is a replicate volume where
the replicas of the object are not in sync, then readdirp followed by fops might
lead data being served from the subvolume which is not in sync with latest
data. And since lookup is needed to trigger self-heal on that object the
consumers might keep getting wrong data until an explicit lookup is not done.

Fuse handles this situation by sending an explicit lookup by itself (fuse
xlator) on those inodes which are linked via readdirp, whenever a fop comes on
that inode.

The same procedure is done in gfapi as well to address this situation.

Thanks to shyam(srangana@redhat.com) for valuable inputs

Change-Id: I4230fae8e0b01a95c056282b08ed30832d4804a7
BUG: 1240190
Signed-off-by: Raghavendra Bhat <raghavendra@redhat.com>
Reviewed-on: http://review.gluster.org/11545
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Shyamsundar Ranganathan <srangana@redhat.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/api/src/glfs-fops.c b/api/src/glfs-fops.c
index e1762ae1285..b66f336338d 100644
--- a/api/src/glfs-fops.c
+++ b/api/src/glfs-fops.c
@@ -2270,6 +2270,7 @@ glfd_entry_refresh (struct glfs_fd *glfd, int plus)
 	xlator_t        *subvol = NULL;
 	gf_dirent_t      entries;
 	gf_dirent_t      old;
+        gf_dirent_t     *entry = NULL;
 	int              ret = -1;
 	fd_t            *fd = NULL;
 
@@ -2304,8 +2305,20 @@ glfd_entry_refresh (struct glfs_fd *glfd, int plus)
 				      &entries, NULL, NULL);
         DECODE_SYNCOP_ERR (ret);
 	if (ret >= 0) {
-		if (plus)
+		if (plus) {
+                        /**
+                         * Set inode_needs_lookup flag before linking the
+                         * inode. Doing it later post linkage might lead
+                         * to a race where a fop comes after inode link
+                         * but before setting need_lookup flag.
+                         */
+                        list_for_each_entry (entry, &glfd->entries, list) {
+                                if (entry->inode)
+                                        inode_set_need_lookup (entry->inode, THIS);
+                        }
+
 			gf_link_inodes_from_dirent (THIS, fd->inode, &entries);
+                }
 
 		list_splice_init (&glfd->entries, &old.list);
 		list_splice_init (&entries.list, &glfd->entries);
@@ -2314,6 +2327,7 @@ glfd_entry_refresh (struct glfs_fd *glfd, int plus)
 		errno = 0;
 	}
 
+
 	if (ret > 0)
 		glfd->next = list_entry (glfd->entries.next, gf_dirent_t, list);