[PATCH 1/2] cephfs: ignore error from invalidate_inode_pages2_range() in direct write.

From: NeilBrown <neilb@suse.com>
To: "Yan, Zheng" <zyan@redhat.com>, Sage Weil <sage@redhat.com>,
	Ilya Dryomov <idryomov@gmail.com>
Cc: ceph-devel@vger.kernel.org
Subject: [PATCH 1/2] cephfs: ignore error from invalidate_inode_pages2_range() in direct write.
Date: Wed, 31 Aug 2016 12:58:49 +1000	[thread overview]
Message-ID: <871t15ej9y.fsf@notabene.neil.brown.name> (raw)
In-Reply-To: <874m61eje0.fsf@notabene.neil.brown.name>

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This call can fail if there are dirty pages.  The preceding call to
filemap_write_and_wait_range() will normally remove dirty pages, but
as inode_lock() is not held over calls to ceph_direct_read_write(), it
could race with non-direct writes and pages could be dirtied
immediately after filemap_write_and_wait_range() returns

If there are dirty pages, they will be removed by the subsequent call
to truncate_inode_pages_range(), so having them here is not a problem.

If the 'ret' value is left holding an error, then in the async IO case
(aio_req is not NULL) the loop that would normally call
ceph_osdc_start_request() will see the error in 'ret' and abort all
requests.  This doesn't seem like correct behaviour.

So clear 'ret' and ignore the error (other than the dout() message).

Signed-off-by: NeilBrown <neilb@suse.com>
---
 fs/ceph/file.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 0f5375d8e030..1ca6e29edcc9 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -905,8 +905,14 @@ ceph_direct_read_write(struct kiocb *iocb, struct iov_iter *iter,
 		ret = invalidate_inode_pages2_range(inode->i_mapping,
 					pos >> PAGE_SHIFT,
 					(pos + count) >> PAGE_SHIFT);
-		if (ret < 0)
+		if (ret < 0) {
 			dout("invalidate_inode_pages2_range returned %d\n", ret);
+			/*
+			 * Error is not fatal as we truncate_inode_pages_range()
+			 * below.
+			 */
+			ret = 0;
+		}
 
 		flags = CEPH_OSD_FLAG_ORDERSNAP |
 			CEPH_OSD_FLAG_ONDISK |
-- 
2.9.3


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