gfapi : Resolve "." and ".." only for named lookups

The patch https://review.gluster.org/#/c/17177 resolves "." and ".."
to corrosponding inodes and names before sending the request to the
backend server. But this will only work if inode and its parent is
linked properly. Incase of nameless lookup(applications like ganesha)
the inode of parent can be NULL(only gfid is send). So this patch will
resolve "." and ".." only if proper parent is available

Upstream reference
>Change-Id: I4c50258b0d896dabf000a547ab180b57df308a0b
>BUG: 1460514
>Signed-off-by: Jiffin Tony Thottan <jthottan@redhat.com>
>Reviewed-on: https://review.gluster.org/17502
>Smoke: Gluster Build System <jenkins@build.gluster.org>
>NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
>Reviewed-by: Poornima G <pgurusid@redhat.com>
>CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
>Reviewed-by: soumya k <skoduri@redhat.com>
>Reviewed-by: Jeff Darcy <jeff@pl.atyp.us>
>(cherry picked from commit a052b413242783f39cb3312a6a02bdd025b10f0c)

Change-Id: I4c50258b0d896dabf000a547ab180b57df308a0b
BUG: 1559352
Signed-off-by: Jiffin Tony Thottan <jthottan@redhat.com>

3 files changed, 83 insertions, 124 deletions

diff --git a/api/src/glfs-resolve.c b/api/src/glfs-resolve.c
index a2be87f1c1e..7ebd4f49ddf 100644
--- a/api/src/glfs-resolve.c
+++ b/api/src/glfs-resolve.c
@@ -236,6 +236,7 @@ glfs_resolve_component (struct glfs *fs, xlator_t *subvol, inode_t *parent,
 {
 	loc_t        loc = {0, };
 	inode_t     *inode = NULL;
+        inode_t     *temp_parent = NULL;
 	int          reval = 0;
 	int          ret = -1;
 	int          glret = -1;
@@ -244,14 +245,12 @@ glfs_resolve_component (struct glfs *fs, xlator_t *subvol, inode_t *parent,
 	dict_t      *xattr_req = NULL;
         uint64_t     ctx_value = LOOKUP_NOT_NEEDED;
 
-	loc.name = component;
-
 	loc.parent = inode_ref (parent);
 	gf_uuid_copy (loc.pargfid, parent->gfid);
 
-        /* At this point we should never have '.' or ".." in path */
         if (__is_root_gfid (parent->gfid) &&
-            (strcmp (component, "/") == 0)) {
+            ((strcmp (component, ".") == 0) ||
+             (strcmp (component, "..") == 0))) {
                 if (!force_lookup) {
                         inode = inode_ref (parent);
                 } else {
@@ -261,8 +260,68 @@ glfs_resolve_component (struct glfs *fs, xlator_t *subvol, inode_t *parent,
                 }
                 goto found;
         }
+        /* *
+        * if the component name is either "." or "..", it will try to
+        * resolve that if inode has a proper parent (named lookup).
+        *
+        * Below condition works like this
+        *
+        * Example 1 :
+        * Path /out_dir/dir/in_dir/.
+        *     In put values :
+        *         parent = in_dir
+        *         component : "."
+        *
+        *      Out put values:
+        *         parent : dir
+        *         component : "in_dir"
+        *
+        * Example 2 :
+        * Path /out_dir/dir/in_dir/..
+        *     In put values :
+        *         parent = in_dir
+        *         component : ".."
+        *
+        *     Out put values:
+        *         parent : output_dir
+        *         component : "dir"
+        *
+        * Incase of nameless lookup, both "." and ".." retained
+        */
+
+        if (strcmp (component, ".") == 0) {
+                loc.inode = inode_ref (parent);
+                temp_parent = inode_parent (loc.inode, 0, 0);
+                if (temp_parent) {
+                        inode_unref (loc.parent);
+                        loc.parent = temp_parent;
+                        inode_find_directory_name (loc.inode, &loc.name);
+                }
+
+        } else if (strcmp (component, "..") == 0) {
+                loc.inode = inode_parent (parent, 0, 0);
+                if (loc.inode) {
+                        temp_parent = inode_parent (loc.inode, 0, 0);
+                        if (temp_parent) {
+                                inode_unref (loc.parent);
+                                loc.parent = temp_parent;
+                                inode_find_directory_name (loc.inode, &loc.name);
+                        } else if (__is_root_gfid (loc.inode->gfid)) {
+                                inode_unref (loc.parent);
+                                loc.parent = inode_ref (loc.inode);
+                                loc.name = "";
+                        } else {
+                                inode_unref (loc.inode);
+                                loc.inode = NULL;
+                        }
+
+                }
+        } else
+                loc.inode = inode_grep (parent->table, parent, component);
+
+        if (!loc.name)
+                loc.name = component;
 
-        loc.inode = inode_grep (parent->table, parent, component);
 	if (loc.inode) {
 		gf_uuid_copy (loc.gfid, loc.inode->gfid);
 		reval = 1;
@@ -357,7 +416,6 @@ found:
 out:
 	if (xattr_req)
 		dict_unref (xattr_req);
-
 	loc_wipe (&loc);
 
 	return inode;
@@ -377,7 +435,6 @@ priv_glfs_resolve_at (struct glfs *fs, xlator_t *subvol, inode_t *at,
 	char       *next_component = NULL;
 	int         ret = -1;
 	struct iatt ciatt = {0, };
-        char        dentry_name[PATH_MAX]  = {0, };
 
 	DECLARE_OLD_THIS;
 	__GLFS_ENTRY_VALIDATE_FS(fs, invalid_fs);
@@ -409,7 +466,6 @@ priv_glfs_resolve_at (struct glfs *fs, xlator_t *subvol, inode_t *at,
 		if (parent)
 			inode_unref (parent);
 		parent = inode;
-                glusterfs_normalize_dentry (&parent, &component, dentry_name);
 		inode = glfs_resolve_component (fs, subvol, parent,
 						component, &ciatt,
 						/* force hard lookup on the last
diff --git a/libglusterfs/src/inode.c b/libglusterfs/src/inode.c
index 819d3a8c524..7aa4ee6289a 100644
--- a/libglusterfs/src/inode.c
+++ b/libglusterfs/src/inode.c
@@ -2561,112 +2561,30 @@ out:
         return size;
 }
 
-static void
-inode_parent_null_check(inode_t **parent, inode_t *inode, char **component)
-{
-        GF_VALIDATE_OR_GOTO ("inode", inode, out);
-        GF_VALIDATE_OR_GOTO ("inode", (*component), out);
-
-        if (!(*parent) && __is_root_gfid (inode->gfid)) {
-                *parent = inode_ref (inode);
-                *component = "/";
-        }
-out:
-        return;
-}
-
-/*
- * This function changes component name and parent inode
- * if the component name is either "." or ".."
- *
- * @Paramas:
- * Parent : Parent inode of current dentry
- * component : component name that we need to test
- * dentry_name : Address for memory if need to change component.
- *               The caller has to preallocate this memory with
- *               PATH_MAX as the size.
- *
- * We return the updated parent inode and component in the
- * respective structures.
- *
- * Basic Idea of the function:
- *
- * Example 1 :
- * Path /out_dir/dir/in_dir/.
- *     In put values :
- *         parent = in_dir
- *         component : "."
- *
- *     Out put values:
- *         parent : dir
- *         component : "in_dir"
- *
- * Example 2 :
- * Path /out_dir/dir/in_dir/..
- *     In put values :
- *         parent = in_dir
- *         component : ".."
- *
- *     Out put values:
- *         parent : output_dir
- *         component : "dir"
- */
+/* *
+ * This function finds name of the inode, if it has dentry. The dentry will be
+ * created only if inode_link happens with valid parent and name. And this
+ * function is only applicable for directories because multiple dentries are
+ * not possible(no hardlinks)
+ * */
 void
-glusterfs_normalize_dentry (inode_t **parent, char **component,
-                          char *dentry_name)
-{
-        inode_t         *temp_inode             = NULL;
-        dentry_t        *dentry                 = NULL;
+inode_find_directory_name (inode_t *inode, const char **name) {
+        dentry_t *dentry = NULL;
 
-        GF_VALIDATE_OR_GOTO ("inode", (*parent), out);
-        GF_VALIDATE_OR_GOTO ("inode", (*component), out);
-        GF_VALIDATE_OR_GOTO ("inode", (dentry_name), out);
+        GF_VALIDATE_OR_GOTO ("inode", inode, out);
+        GF_VALIDATE_OR_GOTO ("inode", name, out);
 
-        /* After this point, there should not be "." or ".."
-         * in the path. Dot and double dots are replaced with
-         * appropriate base name and parent inode.
-         */
+        if (!IA_ISDIR (inode->ia_type))
+                return;
 
-        /* During the resolving, if it goes beyond the mount point
-         * we do lookup on the mount itself like "/.. " will be
-         * converted as "/"
-         */
-        if (strcmp (*component, ".") == 0) {
-                temp_inode = *parent;
-                *parent = inode_parent (*parent, 0, 0);
-                inode_parent_null_check (parent, temp_inode, component);
-                pthread_mutex_lock (&temp_inode->table->lock);
-                {
-                        dentry = __dentry_search_arbit (temp_inode);
-                        if (dentry) {
-                                snprintf (dentry_name, PATH_MAX, "%s",
-                                          dentry->name);
-                                *component = dentry_name;
-                        }
-                }
-                pthread_mutex_unlock (&temp_inode->table->lock);
-                inode_unref (temp_inode);
-        } else if (strcmp (*component, "..") == 0) {
-                temp_inode = *parent;
-                *parent = inode_parent (*parent, 0, 0);
-                inode_parent_null_check (parent, temp_inode, component);
-                inode_unref (temp_inode);
-
-                temp_inode = *parent;
-                *parent = inode_parent (*parent, 0, 0);
-                inode_parent_null_check (parent, temp_inode, component);
-                pthread_mutex_lock (&temp_inode->table->lock);
-                {
-                        dentry = __dentry_search_arbit (temp_inode);
-                        if (dentry) {
-                                snprintf (dentry_name, PATH_MAX, "%s",
-                                          dentry->name);
-                                *component = dentry_name;
-                        }
+        pthread_mutex_lock (&inode->table->lock);
+        {
+                dentry = __dentry_search_arbit (inode);
+                if (dentry) {
+                        *name = dentry->name;
                 }
-                pthread_mutex_unlock (&temp_inode->table->lock);
-                inode_unref (temp_inode);
         }
+        pthread_mutex_unlock (&inode->table->lock);
 out:
         return;
 }
diff --git a/libglusterfs/src/inode.h b/libglusterfs/src/inode.h
index 253196378a8..b82b6bac2c7 100644
--- a/libglusterfs/src/inode.h
+++ b/libglusterfs/src/inode.h
@@ -286,21 +286,6 @@ inode_has_dentry (inode_t *inode);
 size_t
 inode_ctx_size (inode_t *inode);
 
-/*
- * This function is used to change the dentry from a path
- * if it contains any "." or ".." .
- *
- * It replaces "." and ".." to proper bname after resolving
- * and will change the component accordingly.
- *
- * This fucntion also replaces the parent inode based on the
- * bname.
- *
- * We should give a allocated memory as a third argument to store
- * the component in case if we are modifying it.
- */
-
 void
-glusterfs_normalize_dentry (inode_t **parent, char **component,
-                            char *dentry_name);
+inode_find_directory_name (inode_t *inode, const char **name);
 #endif /* _INODE_H */