fuse: writepage: skip already in flight

If ->writepage() tries to write back a page whose copy is still in flight,
then just skip by calling redirty_page_for_writepage().

This is OK, since now ->writepage() should never be called for data
integrity sync.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index f8ff019cc6ec..135360e2b9e5 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1591,6 +1591,18 @@ static int fuse_writepage(struct page *page, struct writeback_control *wbc)
 {
         int err;
 
+        if (fuse_page_is_writeback(page->mapping->host, page->index)) {
+                /*
+                 * ->writepages() should be called for sync() and friends.  We
+                 * should only get here on direct reclaim and then we are
+                 * allowed to skip a page which is already in flight
+                 */
+                WARN_ON(wbc->sync_mode == WB_SYNC_ALL);
+
+                redirty_page_for_writepage(wbc, page);
+                return 0;
+        }
+
         err = fuse_writepage_locked(page);
         unlock_page(page);