Re: [Regression 6.1.y] From "cifs: Fix flushing, invalidation and file size with copy_file_range()"

From: Steve French <smfrench@gmail.com>
To: David Howells <dhowells@redhat.com>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	Salvatore Bonaccorso <carnil@debian.org>,
	 Paulo Alcantara <pc@manguebit.com>,
	Shyam Prasad N <nspmangalore@gmail.com>,
	 Rohith Surabattula <rohiths.msft@gmail.com>,
	Matthew Wilcox <willy@infradead.org>,
	 Jeff Layton <jlayton@kernel.org>,
	Steve French <stfrench@microsoft.com>,
	 "Jitindar Singh, Suraj" <surajjs@amazon.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	 "stable-commits@vger.kernel.org"
	<stable-commits@vger.kernel.org>,
	stable@vger.kernel.org,  linux-cifs@vger.kernel.org,
	 Linux regressions mailing list <regressions@lists.linux.dev>
Subject: Re: [Regression 6.1.y] From "cifs: Fix flushing, invalidation and file size with copy_file_range()"
Date: Fri, 12 Jan 2024 23:20:53 -0600	[thread overview]
Message-ID: <CAH2r5mtBSvp9D8s3bX7KNWjXdTuOHPx5Z005jp8F5kuJgU3Z-g@mail.gmail.com> (raw)
In-Reply-To: <2162049.1705069551@warthog.procyon.org.uk>

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Here is a patch similar to what David suggested.  Seems
straightforward fix.  See attached.
I did limited testing on it tonight with 6.1 (will do more tomorrow,
but feedback welcome) but it did fix the regression in xfstest
generic/001 mentioned in this thread.




On Fri, Jan 12, 2024 at 8:26 AM David Howells <dhowells@redhat.com> wrote:
>
> gregkh@linuxfoundation.org <gregkh@linuxfoundation.org> wrote:
>
> > I guess I can just revert the single commit here?  Can someone send me
> > the revert that I need to do so as I get it right?
>
> In cifs_flush_folio() the error check for filemap_get_folio() just needs
> changing to check !folio instead of IS_ERR(folio).
>
> David
>
>


--
Thanks,

Steve

[-- Attachment #2: 0001-cifs-fix-flushing-folio-regression-for-6.1-backport.patch --]
[-- Type: text/x-patch, Size: 1157 bytes --]

From ba288a873fb8ac3d1bf5563366558a905620c071 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Fri, 12 Jan 2024 23:08:51 -0600
Subject: [PATCH] cifs: fix flushing folio regression for 6.1 backport

filemap_get_folio works differenty in 6.1 vs. later kernels
(returning NULL in 6.1 instead of an error).  Add
this minor correction which addresses the regression in the patch:
  cifs: Fix flushing, invalidation and file size with copy_file_range()

Suggested-by: David Howells <dhowells@redhat.com>
Reported-by: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/smb/client/cifsfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c
index 2e15b182e59f..ac0b7f229a23 100644
--- a/fs/smb/client/cifsfs.c
+++ b/fs/smb/client/cifsfs.c
@@ -1240,7 +1240,7 @@ static int cifs_flush_folio(struct inode *inode, loff_t pos, loff_t *_fstart, lo
 	int rc = 0;
 
 	folio = filemap_get_folio(inode->i_mapping, index);
-	if (IS_ERR(folio))
+	if ((!folio) || (IS_ERR(folio)))
 		return 0;
 
 	size = folio_size(folio);
-- 
2.40.1

