f2fs: remove unnecessary f2fs_lock_op in f2fs_new_inode

This can be removed, since f2fs_alloc_nid() actually doesn't require to block
checkpoint and __f2fs_build_free_nids() is covered by nm_i->nat_tree_lock.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/namei.c

@@ -37,13 +37,10 @@ static struct inode *f2fs_new_inode(struct user_namespace *mnt_userns,
 	if (!inode)
 		return ERR_PTR(-ENOMEM);
 
-	f2fs_lock_op(sbi);
 	if (!f2fs_alloc_nid(sbi, &ino)) {
-		f2fs_unlock_op(sbi);
 		err = -ENOSPC;
 		goto fail;
 	}
-	f2fs_unlock_op(sbi);
 
 	nid_free = true;