Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753036Ab3JCJ5K (ORCPT ); Thu, 3 Oct 2013 05:57:10 -0400 Received: from mail-ea0-f175.google.com ([209.85.215.175]:36976 "EHLO mail-ea0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751374Ab3JCJ5I (ORCPT ); Thu, 3 Oct 2013 05:57:08 -0400 Date: Thu, 3 Oct 2013 11:57:49 +0200 From: Miklos Szeredi To: Maxim Patlasov Cc: fuse-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] fuse: writepages: crop secondary requests Message-ID: <20131003095749.GB14242@tucsk.piliscsaba.szeredi.hu> References: <20131002173701.31188.33547.stgit@dhcp-10-30-17-2.sw.ru> <20131002173823.31188.77171.stgit@dhcp-10-30-17-2.sw.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131002173823.31188.77171.stgit@dhcp-10-30-17-2.sw.ru> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3348 Lines: 88 On Wed, Oct 02, 2013 at 09:38:32PM +0400, Maxim Patlasov wrote: > If writeback happens while fuse is in FUSE_NOWRITE condition, the request > will be queued but not processed immediately (see fuse_flush_writepages()). > Until FUSE_NOWRITE becomes relaxed, more writebacks can happen. They will > be queued as "secondary" requests to that first ("primary") request. > > Existing implementation crops only primary request. This is not correct > because a subsequent extending write(2) may increase i_size and then secondary > requests won't be cropped properly. The result would be stale data written to > the server to a file offset where zeros must be. > > Similar problem may happen if secondary requests are attached to an in-flight > request that was already cropped. > > The patch solves the issue by cropping all secondary requests in > fuse_writepage_end(). Thanks to Miklos for idea. How about this, even simpler, one? Thanks, Miklos Index: linux/fs/fuse/file.c =================================================================== --- linux.orig/fs/fuse/file.c 2013-10-03 11:27:00.597084704 +0200 +++ linux/fs/fuse/file.c 2013-10-03 11:53:30.477208467 +0200 @@ -1436,12 +1436,12 @@ static void fuse_writepage_finish(struct } /* Called under fc->lock, may release and reacquire it */ -static void fuse_send_writepage(struct fuse_conn *fc, struct fuse_req *req) +static void fuse_send_writepage(struct fuse_conn *fc, struct fuse_req *req, + loff_t size) __releases(fc->lock) __acquires(fc->lock) { struct fuse_inode *fi = get_fuse_inode(req->inode); - loff_t size = i_size_read(req->inode); struct fuse_write_in *inarg = &req->misc.write.in; __u64 data_size = req->num_pages * PAGE_CACHE_SIZE; @@ -1476,7 +1476,7 @@ __acquires(fc->lock) * * Called with fc->lock */ -void fuse_flush_writepages(struct inode *inode) +void __fuse_flush_writepages(struct inode *inode, loff_t crop) __releases(fc->lock) __acquires(fc->lock) { @@ -1487,9 +1487,15 @@ __acquires(fc->lock) while (fi->writectr >= 0 && !list_empty(&fi->queued_writes)) { req = list_entry(fi->queued_writes.next, struct fuse_req, list); list_del_init(&req->list); - fuse_send_writepage(fc, req); + fuse_send_writepage(fc, req, crop); } } +void fuse_flush_writepages(struct inode *inode) +__releases(fc->lock) +__acquires(fc->lock) +{ + __fuse_flush_writepages(inode, i_size_read(inode)); +} static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_req *req) { @@ -1499,12 +1505,13 @@ static void fuse_writepage_end(struct fu mapping_set_error(inode->i_mapping, req->out.h.error); spin_lock(&fc->lock); while (req->misc.write.next) { + struct fuse_write_in *inarg = &req->misc.write.in; struct fuse_req *next = req->misc.write.next; req->misc.write.next = next->misc.write.next; next->misc.write.next = NULL; list_add(&next->writepages_entry, &fi->writepages); list_add_tail(&next->list, &fi->queued_writes); - fuse_flush_writepages(inode); + __fuse_flush_writepages(inode, inarg->offset + inarg->size); } fi->writectr--; fuse_writepage_finish(fc, req); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/