[PATCH] vfs: allow copy_file_range from a swapfile

From: Amir Goldstein <amir73il@gmail.com>
To: "Darrick J . Wong" <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>,
	Christoph Hellwig <hch@lst.de>, Theodore Ts'o <tytso@mit.edu>,
	linux-xfs@vger.kernel.org,
	Olga Kornievskaia <olga.kornievskaia@gmail.com>,
	Luis Henriques <lhenriques@suse.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org,
	ceph-devel@vger.kernel.org, linux-nfs@vger.kernel.org,
	linux-cifs@vger.kernel.org
Subject: [PATCH] vfs: allow copy_file_range from a swapfile
Date: Mon, 10 Jun 2019 20:26:06 +0300	[thread overview]
Message-ID: <20190610172606.4119-1-amir73il@gmail.com> (raw)

read(2) is allowed from a swapfile, so copy_file_range(2) should
be allowed as well.

Reported-by: Theodore Ts'o <tytso@mit.edu>
Fixes: 96e6e8f4a68d ("vfs: add missing checks to copy_file_range")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---

Darrick,

This fixes the generic/554 issue reported by Ted.

I intend to remove the test case of copy from swap file from
generic/554, so test is expected to pass with or without this fix.
But if you wait for next week's xfstests update before applying
this fix, then at lease maintainer that run current xfstests master
could use current copy-file-range-fixes branch to pass the tests.

Thanks,
Amir.

 mm/filemap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index aac71aef4c61..f74e5ce7ca50 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3081,7 +3081,7 @@ int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
 	if (IS_IMMUTABLE(inode_out))
 		return -EPERM;
 
-	if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
+	if (IS_SWAPFILE(inode_out))
 		return -ETXTBSY;
 
 	/* Ensure offsets don't wrap. */
-- 
2.17.1

