Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754858Ab3HPLaP (ORCPT ); Fri, 16 Aug 2013 07:30:15 -0400 Received: from relay.parallels.com ([195.214.232.42]:49730 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754471Ab3HPLaL (ORCPT ); Fri, 16 Aug 2013 07:30:11 -0400 Subject: [PATCH 2/2] fuse: wait for writeback in fuse_file_fallocate() -v2 From: Maxim Patlasov Cc: miklos@szeredi.hu, fuse-devel@lists.sourceforge.net, bfoster@redhat.com, xemul@parallels.com, linux-kernel@vger.kernel.org, devel@openvz.org Date: Fri, 16 Aug 2013 15:30:27 +0400 Message-ID: <20130816112854.5630.1907.stgit@maximpc.sw.ru> In-Reply-To: <20130812163935.10366.88320.stgit@maximpc.sw.ru> References: <20130812163935.10366.88320.stgit@maximpc.sw.ru> User-Agent: StGit/0.15 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3704 Lines: 116 The patch fixes a race between mmap-ed write and fallocate(PUNCH_HOLE): 1) An user makes a page dirty via mmap-ed write. 2) The user performs fallocate(2) with mode == PUNCH_HOLE|KEEP_SIZE and covering the page. 3) Before truncate_pagecache_range call from fuse_file_fallocate, the page goes to write-back. The page is fully processed by fuse_writepage (including end_page_writeback on the page), but fuse_flush_writepages did nothing because fi->writectr < 0. 4) truncate_pagecache_range is called and fuse_file_fallocate is finishing by calling fuse_release_nowrite. The latter triggers processing queued write-back request which will write stale data to the hole soon. Changed in v2 (thanks to Brian for suggestion): - Do not truncate page cache until FUSE_FALLOCATE succeeded. Otherwise, we can end up in returning -ENOTSUPP while user data is already punched from page cache. Use filemap_write_and_wait_range() instead. Signed-off-by: Maxim Patlasov --- fs/fuse/file.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++------ 1 files changed, 48 insertions(+), 6 deletions(-) diff --git a/fs/fuse/file.c b/fs/fuse/file.c index d1715b3..e88ba8b 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -344,6 +344,31 @@ static bool fuse_page_is_writeback(struct inode *inode, pgoff_t index) return found; } +static bool fuse_range_is_writeback(struct inode *inode, pgoff_t idx_from, + pgoff_t idx_to) +{ + struct fuse_conn *fc = get_fuse_conn(inode); + struct fuse_inode *fi = get_fuse_inode(inode); + struct fuse_req *req; + bool found = false; + + spin_lock(&fc->lock); + list_for_each_entry(req, &fi->writepages, writepages_entry) { + pgoff_t curr_index; + + BUG_ON(req->inode != inode); + curr_index = req->misc.write.in.offset >> PAGE_CACHE_SHIFT; + if (!(idx_from >= curr_index + req->num_pages || + idx_to < curr_index)) { + found = true; + break; + } + } + spin_unlock(&fc->lock); + + return found; +} + /* * Wait for page writeback to be completed. * @@ -358,6 +383,19 @@ static int fuse_wait_on_page_writeback(struct inode *inode, pgoff_t index) return 0; } +static void fuse_wait_on_writeback(struct inode *inode, pgoff_t start, + size_t bytes) +{ + struct fuse_inode *fi = get_fuse_inode(inode); + pgoff_t idx_from, idx_to; + + idx_from = start >> PAGE_CACHE_SHIFT; + idx_to = (start + bytes - 1) >> PAGE_CACHE_SHIFT; + + wait_event(fi->page_waitq, + !fuse_range_is_writeback(inode, idx_from, idx_to)); +} + static int fuse_flush(struct file *file, fl_owner_t id) { struct inode *inode = file_inode(file); @@ -2478,8 +2516,15 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset, if (lock_inode) { mutex_lock(&inode->i_mutex); - if (mode & FALLOC_FL_PUNCH_HOLE) - fuse_set_nowrite(inode); + if (mode & FALLOC_FL_PUNCH_HOLE) { + loff_t endbyte = offset + length - 1; + err = filemap_write_and_wait_range(inode->i_mapping, + offset, endbyte); + if (err) + goto out; + + fuse_wait_on_writeback(inode, offset, length); + } } req = fuse_get_req_nopages(fc); @@ -2514,11 +2559,8 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset, fuse_invalidate_attr(inode); out: - if (lock_inode) { - if (mode & FALLOC_FL_PUNCH_HOLE) - fuse_release_nowrite(inode); + if (lock_inode) mutex_unlock(&inode->i_mutex); - } return err; } -- 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/