fuse: don't BUG on no write file

Don't bug if there's no writable files found for page writeback.  If ever
this is triggered, a WARN_ON helps debugging it much better then a BUG_ON.

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

1 files changed, 12 insertions, 5 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 6fb9425c23c6..6ce0066d7c8c 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1505,12 +1505,14 @@ static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_req *req)
 static struct fuse_file *fuse_write_file(struct fuse_conn *fc,
                                          struct fuse_inode *fi)
 {
-        struct fuse_file *ff;
+        struct fuse_file *ff = NULL;
 
         spin_lock(&fc->lock);
-        BUG_ON(list_empty(&fi->write_files));
-        ff = list_entry(fi->write_files.next, struct fuse_file, write_entry);
-        fuse_file_get(ff);
+        if (!WARN_ON(list_empty(&fi->write_files))) {
+                ff = list_entry(fi->write_files.next, struct fuse_file,
+                                write_entry);
+                fuse_file_get(ff);
+        }
         spin_unlock(&fc->lock);
 
         return ff;
@@ -1524,6 +1526,7 @@ static int fuse_writepage_locked(struct page *page)
         struct fuse_inode *fi = get_fuse_inode(inode);
         struct fuse_req *req;
         struct page *tmp_page;
+        int error = -ENOMEM;
 
         set_page_writeback(page);
 
@@ -1536,7 +1539,11 @@ static int fuse_writepage_locked(struct page *page)
         if (!tmp_page)
                 goto err_free;
 
+        error = -EIO;
         req->ff = fuse_write_file(fc, fi);
+        if (!req->ff)
+                goto err_free;
+
         fuse_write_fill(req, req->ff, page_offset(page), 0);
 
         copy_highpage(tmp_page, page);
@@ -1566,7 +1573,7 @@ err_free:
         fuse_request_free(req);
 err:
         end_page_writeback(page);
-        return -ENOMEM;
+        return error;
 }
 
 static int fuse_writepage(struct page *page, struct writeback_control *wbc)