f2fs: let's avoid to get cp_rwsem twice by f2fs_evict_inode by d_invalidate

f2fs_unlink
 -> f2fs_lock_op
 -> d_invalidate
  -> shrink_dentry_list
   -> iput_final
    -> f2fs_evict_inode
     -> f2fs_lock_op
Reviewed-by: Chao Yu <chao@kernel.org>
Tested-by: Yangtao Li <frank.li@vivo.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/namei.c

@@ -632,6 +632,8 @@ static int f2fs_unlink(struct inode *dir, struct dentry *dentry)
 		goto fail;
 	}
 	f2fs_delete_entry(de, page, dir, inode);
+	f2fs_unlock_op(sbi);
+
 #if IS_ENABLED(CONFIG_UNICODE)
 	/* VFS negative dentries are incompatible with Encoding and
 	 * Case-insensitiveness. Eventually we'll want avoid
@@ -642,8 +644,6 @@ static int f2fs_unlink(struct inode *dir, struct dentry *dentry)
 	if (IS_CASEFOLDED(dir))
 		d_invalidate(dentry);
 #endif
-	f2fs_unlock_op(sbi);
-
 	if (IS_DIRSYNC(dir))
 		f2fs_sync_fs(sbi->sb, 1);
 fail: