linux-kernel - [PATCH 4.9 082/117] cachefiles: Handle readpage error correctly

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Message-Id: <20201109125029.580735387@linuxfoundation.org>
Date:   Mon,  9 Nov 2020 13:55:08 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        David Howells <dhowells@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.9 082/117] cachefiles: Handle readpage error correctly

From: Matthew Wilcox (Oracle) <willy@...radead.org>

commit 9480b4e75b7108ee68ecf5bc6b4bd68e8031c521 upstream.

If ->readpage returns an error, it has already unlocked the page.

Fixes: 5e929b33c393 ("CacheFiles: Handle truncate unlocking the page we're reading")
Cc: stable@...r.kernel.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Signed-off-by: David Howells <dhowells@...hat.com>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/cachefiles/rdwr.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/cachefiles/rdwr.c
+++ b/fs/cachefiles/rdwr.c
@@ -125,7 +125,7 @@ static int cachefiles_read_reissue(struc
 		_debug("reissue read");
 		ret = bmapping->a_ops->readpage(NULL, backpage);
 		if (ret < 0)
-			goto unlock_discard;
+			goto discard;
 	}
 
 	/* but the page may have been read before the monitor was installed, so
@@ -142,6 +142,7 @@ static int cachefiles_read_reissue(struc
 
 unlock_discard:
 	unlock_page(backpage);
+discard:
 	spin_lock_irq(&object->work_lock);
 	list_del(&monitor->op_link);
 	spin_unlock_irq(&object->work_lock);