fs/9p: Add hardlink support to .u extension

For regular file and directories we put the link
count in th extension field in a tagged string format.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

fs/9p/vfs_inode.c

@@ -887,6 +887,8 @@ v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
 	struct super_block *sb)
 {
 	char ext[32];
+	char tag_name[14];
+	unsigned int i_nlink;
 	struct v9fs_session_info *v9ses = sb->s_fs_info;
 
 	inode->i_nlink = 1;
@@ -902,7 +904,22 @@ v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
 		inode->i_uid = stat->n_uid;
 		inode->i_gid = stat->n_gid;
 	}
-
+	if ((S_ISREG(inode->i_mode)) || (S_ISDIR(inode->i_mode))) {
+		if (v9fs_proto_dotu(v9ses) && (stat->extension[0] != '\0')) {
+			/*
+			 * Hadlink support got added later to
+			 * to the .u extension. So there can be
+			 * server out there that doesn't support
+			 * this even with .u extension. So check
+			 * for non NULL stat->extension
+			 */
+			strncpy(ext, stat->extension, sizeof(ext));
+			/* HARDLINKCOUNT %u */
+			sscanf(ext, "%13s %u", tag_name, &i_nlink);
+			if (!strncmp(tag_name, "HARDLINKCOUNT", 13))
+				inode->i_nlink = i_nlink;
+		}
+	}
 	inode->i_mode = p9mode2unixmode(v9ses, stat->mode);
 	if ((S_ISBLK(inode->i_mode)) || (S_ISCHR(inode->i_mode))) {
 		char type = 0;