protocol/server: forget the inodes which got ENOENT in lookup

If a looked up object is removed from the backend, then upon getting a
revalidated lookup on that object ENOENT error is received. protocol/server
xlator handles it by removing dentry upon which ENOENT is received. But the
inode associated with it still remains in the inode table, and whoever does
nameless lookup on the gfid of that object will be able to do it successfully
despite the object being not present.

For handling this issue, upon getting ENOENT on a looked up entry in revalidate
lookups, protocol/server should forget the inode as well.

Though removing files directly from the backend is not allowed, in case of
objects corrupted due to bitrot and marked as bad by scrubber, objects are
removed directly from the backend in case of replicate volumes, so that the
object is healed from the good copy. For handling this, the inode of the bad
object removed from the backend should be forgotten. Otherwise, the inode which
knows the object it represents is bad, does not allow read/write operations
happening as part of self-heal.

Change-Id: I23b7a5bef919c98eea684aa1e977e317066cfc71
BUG: 1238188
Signed-off-by: Raghavendra Bhat <raghavendra@redhat.com>
Reviewed-on: http://review.gluster.org/11489
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>

2 files changed, 37 insertions, 22 deletions

diff --git a/xlators/protocol/server/src/server-rpc-fops.c b/xlators/protocol/server/src/server-rpc-fops.c
index 6c5d51d3dfb..d2a829f0363 100644
--- a/xlators/protocol/server/src/server-rpc-fops.c
+++ b/xlators/protocol/server/src/server-rpc-fops.c
@@ -27,6 +27,16 @@
                 ret = RPCSVC_ACTOR_ERROR;                       \
         } while (0)
 
+void
+forget_inode_if_no_dentry (inode_t *inode)
+{
+        if (!inode_has_dentry (inode))
+                inode_forget (inode, 0);
+
+        return;
+}
+
+
 /* Callback function section */
 int
 server_statfs_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
@@ -103,6 +113,23 @@ server_lookup_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
                                 inode_unlink (state->loc.inode,
                                               state->loc.parent,
                                               state->loc.name);
+                                /**
+                                 * If the entry is not present, then just
+                                 * unlinking the associated dentry is not
+                                 * suffecient. This condition should be
+                                 * treated as unlink of the entry. So along
+                                 * with deleting the entry, its also important
+                                 * to forget the inode for it (if the dentry
+                                 * being considered was the last dentry).
+                                 * Otherwise it might lead to inode leak.
+                                 * It also might lead to wrong decisions being
+                                 * taken if the future lookups on this inode are
+                                 * successful since they are able to find the
+                                 * inode in the inode table (atleast gfid based
+                                 * lookups will be successful, if the lookup
+                                 * is a soft lookup)
+                                 */
+                                forget_inode_if_no_dentry (state->loc.inode);
                         }
                 }
                 goto out;
@@ -411,7 +438,6 @@ server_rmdir_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
 {
         gfs3_rmdir_rsp       rsp    = {0,};
         server_state_t      *state  = NULL;
-        inode_t             *parent = NULL;
         rpcsvc_request_t    *req    = NULL;
 
         GF_PROTOCOL_DICT_SERIALIZE (this, xdata, &rsp.xdata.xdata_val,
@@ -432,15 +458,11 @@ server_rmdir_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
 
         inode_unlink (state->loc.inode, state->loc.parent,
                       state->loc.name);
-        parent = inode_parent (state->loc.inode, 0, NULL);
-        if (parent)
-                /* parent should not be found for directories after
-                 * inode_unlink, since directories cannot have
-                 * hardlinks.
-                 */
-                inode_unref (parent);
-        else
-                inode_forget (state->loc.inode, 0);
+        /* parent should not be found for directories after
+         * inode_unlink, since directories cannot have
+         * hardlinks.
+         */
+        forget_inode_if_no_dentry (state->loc.inode);
 
         gf_stat_from_iatt (&rsp.preparent, preparent);
         gf_stat_from_iatt (&rsp.postparent, postparent);
@@ -1021,12 +1043,7 @@ server_rename_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         if (tmp_inode) {
                 inode_unlink (tmp_inode, state->loc2.parent,
                               state->loc2.name);
-                tmp_parent = inode_parent (tmp_inode, 0, NULL);
-                if (tmp_parent)
-                        inode_unref (tmp_parent);
-                else
-                        inode_forget (tmp_inode, 0);
-
+                forget_inode_if_no_dentry (tmp_inode);
                 inode_unref (tmp_inode);
         }
 
@@ -1062,7 +1079,6 @@ server_unlink_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
 {
         gfs3_unlink_rsp      rsp    = {0,};
         server_state_t      *state  = NULL;
-        inode_t             *parent = NULL;
         rpcsvc_request_t    *req    = NULL;
 
         GF_PROTOCOL_DICT_SERIALIZE (this, xdata, &rsp.xdata.xdata_val,
@@ -1087,11 +1103,7 @@ server_unlink_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         inode_unlink (state->loc.inode, state->loc.parent,
                       state->loc.name);
 
-        parent = inode_parent (state->loc.inode, 0, NULL);
-        if (parent)
-                inode_unref (parent);
-        else
-                inode_forget (state->loc.inode, 0);
+        forget_inode_if_no_dentry (state->loc.inode);
 
         gf_stat_from_iatt (&rsp.preparent, preparent);
         gf_stat_from_iatt (&rsp.postparent, postparent);
diff --git a/xlators/protocol/server/src/server.h b/xlators/protocol/server/src/server.h
index 6caf44926c9..1055b72dad5 100644
--- a/xlators/protocol/server/src/server.h
+++ b/xlators/protocol/server/src/server.h
@@ -172,4 +172,7 @@ server_submit_reply (call_frame_t *frame, rpcsvc_request_t *req, void *arg,
 int gf_server_check_setxattr_cmd (call_frame_t *frame, dict_t *dict);
 int gf_server_check_getxattr_cmd (call_frame_t *frame, const char *name);
 
+void
+forget_inode_if_no_dentry (inode_t *inode);
+
 #endif /* !_SERVER_H */