wrappers for ->i_mutex access

parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
index 2f77f8d..1b38abd 100644
--- a/fs/ntfs/super.c
+++ b/fs/ntfs/super.c
@@ -1284,10 +1284,10 @@
 	 * Find the inode number for the hibernation file by looking up the
 	 * filename hiberfil.sys in the root directory.
 	 */
-	mutex_lock(&vol->root_ino->i_mutex);
+	inode_lock(vol->root_ino);
 	mref = ntfs_lookup_inode_by_name(NTFS_I(vol->root_ino), hiberfil, 12,
 			&name);
-	mutex_unlock(&vol->root_ino->i_mutex);
+	inode_unlock(vol->root_ino);
 	if (IS_ERR_MREF(mref)) {
 		ret = MREF_ERR(mref);
 		/* If the file does not exist, Windows is not hibernated. */
@@ -1377,10 +1377,10 @@
 	 * Find the inode number for the quota file by looking up the filename
 	 * $Quota in the extended system files directory $Extend.
 	 */
-	mutex_lock(&vol->extend_ino->i_mutex);
+	inode_lock(vol->extend_ino);
 	mref = ntfs_lookup_inode_by_name(NTFS_I(vol->extend_ino), Quota, 6,
 			&name);
-	mutex_unlock(&vol->extend_ino->i_mutex);
+	inode_unlock(vol->extend_ino);
 	if (IS_ERR_MREF(mref)) {
 		/*
 		 * If the file does not exist, quotas are disabled and have
@@ -1460,10 +1460,10 @@
 	 * Find the inode number for the transaction log file by looking up the
 	 * filename $UsnJrnl in the extended system files directory $Extend.
 	 */
-	mutex_lock(&vol->extend_ino->i_mutex);
+	inode_lock(vol->extend_ino);
 	mref = ntfs_lookup_inode_by_name(NTFS_I(vol->extend_ino), UsnJrnl, 8,
 			&name);
-	mutex_unlock(&vol->extend_ino->i_mutex);
+	inode_unlock(vol->extend_ino);
 	if (IS_ERR_MREF(mref)) {
 		/*
 		 * If the file does not exist, transaction logging is disabled,