ceph: remove page upon writeback completion if lost cache cap

This page should have been removed earlier when the cache cap was
revoked, but a writeback was in flight, so it was skipped. We truncate
it here just as the writeback finishes, while it's still locked.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 11 insertions, 0 deletions

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 71f5ad1c1e26..25360d517d1b 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -514,6 +514,7 @@ static void writepages_finish(struct ceph_osd_request *req,
         u64 bytes = 0;
         struct ceph_client *client = ceph_inode_to_client(inode);
         long writeback_stat;
+        unsigned issued = __ceph_caps_issued(ci, NULL);
 
         /* parse reply */
         replyhead = msg->front.iov_base;
@@ -559,6 +560,16 @@ static void writepages_finish(struct ceph_osd_request *req,
                 ceph_put_snap_context(snapc);
                 dout("unlocking %d %p\n", i, page);
                 end_page_writeback(page);
+
+                /*
+                 * We lost the cache cap, need to truncate the page before
+                 * it is unlocked, otherwise we'd truncate it later in the
+                 * page truncation thread, possibly losing some data that
+                 * raced its way in
+                 */
+                if ((issued & CEPH_CAP_FILE_CACHE) == 0)
+                        generic_error_remove_page(inode->i_mapping, page);
+
                 unlock_page(page);
         }
         dout("%p wrote+cleaned %d pages\n", inode, wrote);