linux-kernel - [PATCH 05/13] cifs: Tell the VFS that readpage was synchronous

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Date:   Thu, 17 Sep 2020 16:10:42 +0100
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     linux-fsdevel@...r.kernel.org
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        linux-mm@...ck.org, v9fs-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, linux-afs@...ts.infradead.org,
        ceph-devel@...r.kernel.org, linux-cifs@...r.kernel.org,
        ecryptfs@...r.kernel.org, linux-um@...ts.infradead.org,
        linux-mtd@...ts.infradead.org, Richard Weinberger <richard@....at>
Subject: [PATCH 05/13] cifs: Tell the VFS that readpage was synchronous

The cifs readpage implementation was already synchronous, so use
AOP_UPDATED_PAGE to avoid cycling the page lock.

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
 fs/cifs/file.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index be46fab4c96d..533b151a9143 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -4537,7 +4537,8 @@ static int cifs_readpage_worker(struct file *file, struct page *page,
 	/* send this page to the cache */
 	cifs_readpage_to_fscache(file_inode(file), page);
 
-	rc = 0;
+	kunmap(page);
+	return AOP_UPDATED_PAGE;
 
 io_error:
 	kunmap(page);
@@ -4677,7 +4678,10 @@ static int cifs_write_begin(struct file *file, struct address_space *mapping,
 		 * an error, we don't need to return it. cifs_write_end will
 		 * do a sync write instead since PG_uptodate isn't set.
 		 */
-		cifs_readpage_worker(file, page, &page_start);
+		int err = cifs_readpage_worker(file, page, &page_start);
+
+		if (err == AOP_UPDATED_PAGE)
+			goto out;
 		put_page(page);
 		oncethru = 1;
 		goto start;
-- 
2.28.0