[PATCH 4.4 57/86] cachefiles: Handle readpage error correctly

From: Greg Kroah-Hartman
Date: Mon Nov 09 2020 - 08:45:51 EST


From: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
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);