From 9aae20500d9cd3e7d55d0536d359bdd1c869db89 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Tue, 30 Oct 2018 10:41:01 +1100
Subject: [PATCH] vfs: skip zero-length dedupe requests
Git-commit: 9aae20500d9cd3e7d55d0536d359bdd1c869db89
Patch-mainline: v4.20-rc1
References: bsc#1133851, bsc#1132219
Don't bother calling the filesystem for a zero-length dedupe request;
we can return zero and exit.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Acked-by: Anthony Iliopoulos <ailiopoulos@suse.com>
---
fs/read_write.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -2031,6 +2031,11 @@
if (!dst_file->f_op->dedupe_file_range)
goto out_drop_write;
+ if (len == 0) {
+ ret = 0;
+ goto out_drop_write;
+ }
+
ret = dst_file->f_op->dedupe_file_range(src_file, src_pos,
len, dst_file, dst_pos);
out_drop_write: