fuse: fuse_flush() should wait on writeback

The aim of .flush fop is to hint file-system that flushing its state or caches
or any other important data to reliable storage would be desirable now.
fuse_flush() passes this hint by sending FUSE_FLUSH request to userspace.
However, dirty pages and pages under writeback may be not visible to userspace
yet if we won't ensure it explicitly.

Signed-off-by: Maxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index d8575304c062357f8b18fb6af8b705c2cb86bd6c..d93f2a1aa7de563a22d743ed58ba2b6432cef618 100644 (file)
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -401,6 +401,21 @@ static int fuse_wait_on_page_writeback(struct inode *inode, pgoff_t index)
        return 0;
 }
 
+/*
+ * Wait for all pending writepages on the inode to finish.
+ *
+ * This is currently done by blocking further writes with FUSE_NOWRITE
+ * and waiting for all sent writes to complete.
+ *
+ * This must be called under i_mutex, otherwise the FUSE_NOWRITE usage
+ * could conflict with truncation.
+ */
+static void fuse_sync_writes(struct inode *inode)
+{
+       fuse_set_nowrite(inode);
+       fuse_release_nowrite(inode);
+}
+
 static int fuse_flush(struct file *file, fl_owner_t id)
 {
        struct inode *inode = file_inode(file);
@@ -416,6 +431,14 @@ static int fuse_flush(struct file *file, fl_owner_t id)
        if (fc->no_flush)
                return 0;
 
+       err = filemap_write_and_wait(file->f_mapping);
+       if (err)
+               return err;
+
+       mutex_lock(&inode->i_mutex);
+       fuse_sync_writes(inode);
+       mutex_unlock(&inode->i_mutex);
+
        req = fuse_get_req_nofail_nopages(fc, file);
        memset(&inarg, 0, sizeof(inarg));
        inarg.fh = ff->fh;
@@ -436,21 +459,6 @@ static int fuse_flush(struct file *file, fl_owner_t id)
        return err;
 }
 
-/*
- * Wait for all pending writepages on the inode to finish.
- *
- * This is currently done by blocking further writes with FUSE_NOWRITE
- * and waiting for all sent writes to complete.
- *
- * This must be called under i_mutex, otherwise the FUSE_NOWRITE usage
- * could conflict with truncation.
- */
-static void fuse_sync_writes(struct inode *inode)
-{
-       fuse_set_nowrite(inode);
-       fuse_release_nowrite(inode);
-}
-
 int fuse_fsync_common(struct file *file, loff_t start, loff_t end,
                      int datasync, int isdir)
 {