linux-kernel - [PATCH AUTOSEL 4.19 085/167] CIFS: Fix leaking locked VFS cache pages in writeback retry

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Message-Id: <20190903162519.7136-85-sashal@kernel.org>
Date:   Tue,  3 Sep 2019 12:23:57 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Pavel Shilovsky <pshilov@...rosoft.com>,
        Steve French <stfrench@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>, linux-cifs@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 085/167] CIFS: Fix leaking locked VFS cache pages in writeback retry

From: Pavel Shilovsky <pshilov@...rosoft.com>

[ Upstream commit 165df9a080b6863ae286fa01780c13d87cd81076 ]

If we don't find a writable file handle when retrying writepages
we break of the loop and do not unlock and put pages neither from
wdata2 nor from the original wdata. Fix this by walking through
all the remaining pages and cleanup them properly.

Cc: <stable@...r.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@...rosoft.com>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/cifs/cifssmb.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index a5cb7b2d1ac5d..86a54b809c484 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -2033,12 +2033,13 @@ cifs_writev_requeue(struct cifs_writedata *wdata)
 
 		wdata2->cfile = find_writable_file(CIFS_I(inode), false);
 		if (!wdata2->cfile) {
-			cifs_dbg(VFS, "No writable handles for inode\n");
+			cifs_dbg(VFS, "No writable handle to retry writepages\n");
 			rc = -EBADF;
-			break;
+		} else {
+			wdata2->pid = wdata2->cfile->pid;
+			rc = server->ops->async_writev(wdata2,
+						       cifs_writedata_release);
 		}
-		wdata2->pid = wdata2->cfile->pid;
-		rc = server->ops->async_writev(wdata2, cifs_writedata_release);
 
 		for (j = 0; j < nr_pages; j++) {
 			unlock_page(wdata2->pages[j]);
@@ -2053,6 +2054,7 @@ cifs_writev_requeue(struct cifs_writedata *wdata)
 			kref_put(&wdata2->refcount, cifs_writedata_release);
 			if (is_retryable_error(rc))
 				continue;
+			i += nr_pages;
 			break;
 		}
 
@@ -2060,6 +2062,13 @@ cifs_writev_requeue(struct cifs_writedata *wdata)
 		i += nr_pages;
 	} while (i < wdata->nr_pages);
 
+	/* cleanup remaining pages from the original wdata */
+	for (; i < wdata->nr_pages; i++) {
+		SetPageError(wdata->pages[i]);
+		end_page_writeback(wdata->pages[i]);
+		put_page(wdata->pages[i]);
+	}
+
 	if (rc != 0 && !is_retryable_error(rc))
 		mapping_set_error(inode->i_mapping, rc);
 	kref_put(&wdata->refcount, cifs_writedata_release);
-- 
2.20.1