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/ubifs/dir.c b/fs/ubifs/dir.c
index e49bd28..795992a 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -515,8 +515,8 @@
 	dbg_gen("dent '%pd' to ino %lu (nlink %d) in dir ino %lu",
 		dentry, inode->i_ino,
 		inode->i_nlink, dir->i_ino);
-	ubifs_assert(mutex_is_locked(&dir->i_mutex));
-	ubifs_assert(mutex_is_locked(&inode->i_mutex));
+	ubifs_assert(inode_is_locked(dir));
+	ubifs_assert(inode_is_locked(inode));
 
 	err = dbg_check_synced_i_size(c, inode);
 	if (err)
@@ -572,8 +572,8 @@
 	dbg_gen("dent '%pd' from ino %lu (nlink %d) in dir ino %lu",
 		dentry, inode->i_ino,
 		inode->i_nlink, dir->i_ino);
-	ubifs_assert(mutex_is_locked(&dir->i_mutex));
-	ubifs_assert(mutex_is_locked(&inode->i_mutex));
+	ubifs_assert(inode_is_locked(dir));
+	ubifs_assert(inode_is_locked(inode));
 	err = dbg_check_synced_i_size(c, inode);
 	if (err)
 		return err;
@@ -661,8 +661,8 @@
 
 	dbg_gen("directory '%pd', ino %lu in dir ino %lu", dentry,
 		inode->i_ino, dir->i_ino);
-	ubifs_assert(mutex_is_locked(&dir->i_mutex));
-	ubifs_assert(mutex_is_locked(&inode->i_mutex));
+	ubifs_assert(inode_is_locked(dir));
+	ubifs_assert(inode_is_locked(inode));
 	err = check_dir_empty(c, d_inode(dentry));
 	if (err)
 		return err;
@@ -996,10 +996,10 @@
 	dbg_gen("dent '%pd' ino %lu in dir ino %lu to dent '%pd' in dir ino %lu",
 		old_dentry, old_inode->i_ino, old_dir->i_ino,
 		new_dentry, new_dir->i_ino);
-	ubifs_assert(mutex_is_locked(&old_dir->i_mutex));
-	ubifs_assert(mutex_is_locked(&new_dir->i_mutex));
+	ubifs_assert(inode_is_locked(old_dir));
+	ubifs_assert(inode_is_locked(new_dir));
 	if (unlink)
-		ubifs_assert(mutex_is_locked(&new_inode->i_mutex));
+		ubifs_assert(inode_is_locked(new_inode));
 
 
 	if (unlink && is_dir) {