From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([65.50.211.133]:59130 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750930AbdGZRLF (ORCPT ); Wed, 26 Jul 2017 13:11:05 -0400 Date: Wed, 26 Jul 2017 10:11:01 -0700 From: Matthew Wilcox To: OGAWA Hirofumi Cc: Johannes Thumshirn , Ross Zwisler , "Kani, Toshimitsu" , "linux-nvdimm@lists.01.org" , "linux-fsdevel@vger.kernel.org" Subject: Re: FIle copy to FAT FS on NVDIMM hits BUG_ON at fs/buffer.c:3305! Message-ID: <20170726171101.GA15980@bombadil.infradead.org> References: <1501018096.2042.70.camel@hpe.com> <20170725222247.GA26391@linux.intel.com> <20170726082159.GE4039@linux-x5ow.site> <87d18neemb.fsf@devron> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87d18neemb.fsf@devron> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, Jul 26, 2017 at 06:23:08PM +0900, OGAWA Hirofumi wrote: > The locking of this path seems to be broken. The guy familiar to > bdev_write_page() path will made real fix though, The following patch > should be explaining enough what is wrong. > > In short, clean_buffers() must be called before unlocking lock_page(). Thanks for that. This should fix the problem while not leaking the unlock_page call outside bdev_write_page. --- 8< --- Signed-off-by: Matthew Wilcox diff --git a/fs/block_dev.c b/fs/block_dev.c index 9941dc8342df..3fbe75bdd257 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -716,10 +716,12 @@ int bdev_write_page(struct block_device *bdev, sector_t sector, set_page_writeback(page); result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, true); - if (result) + if (result) { end_page_writeback(page); - else + } else { + clean_page_buffers(page); unlock_page(page); + } blk_queue_exit(bdev->bd_queue); return result; } diff --git a/fs/mpage.c b/fs/mpage.c index 2e4c41ccb5c9..d97b003f1607 100644 --- a/fs/mpage.c +++ b/fs/mpage.c @@ -468,6 +468,16 @@ static void clean_buffers(struct page *page, unsigned first_unmapped) try_to_free_buffers(page); } +/* + * For situations where we want to clean all buffers attached to a page. + * We don't need to calculate how many buffers are attached to the page, + * we just need to specify a number larger than the maximum number of buffers. + */ +void clean_page_buffers(struct page *page) +{ + clean_buffers(page, PAGE_SIZE); +} + static int __mpage_writepage(struct page *page, struct writeback_control *wbc, void *data) { @@ -605,10 +615,8 @@ static int __mpage_writepage(struct page *page, struct writeback_control *wbc, if (bio == NULL) { if (first_unmapped == blocks_per_page) { if (!bdev_write_page(bdev, blocks[0] << (blkbits - 9), - page, wbc)) { - clean_buffers(page, first_unmapped); + page, wbc)) goto out; - } } bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9), BIO_MAX_PAGES, GFP_NOFS|__GFP_HIGH); diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index c8dae555eccf..446b24cac67d 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -232,6 +232,7 @@ int generic_write_end(struct file *, struct address_space *, loff_t, unsigned, unsigned, struct page *, void *); void page_zero_new_buffers(struct page *page, unsigned from, unsigned to); +void clean_page_buffers(struct page *page); int cont_write_begin(struct file *, struct address_space *, loff_t, unsigned, unsigned, struct page **, void **, get_block_t *, loff_t *);