Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932822AbdDFPvn (ORCPT ); Thu, 6 Apr 2017 11:51:43 -0400 Received: from mail-lf0-f66.google.com ([209.85.215.66]:34652 "EHLO mail-lf0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932626AbdDFPvg (ORCPT ); Thu, 6 Apr 2017 11:51:36 -0400 From: Dmitry Monakhov To: Christoph Hellwig Cc: linux-kernel@vger.kernel.org, darrick.wong@oracle.com, axboe@kernel.dk, tytso@mit.edu, jack@suse.cz, hch@infradead.org Subject: Re: [PATCH 5/5] block: truncate page cache only when necessary on fallocate In-Reply-To: <20170406154302.GB16767@infradead.org> References: <1491480169-1889-1-git-send-email-dmonakhov@openvz.org> <1491480169-1889-6-git-send-email-dmonakhov@openvz.org> <20170406154302.GB16767@infradead.org> Date: Thu, 06 Apr 2017 18:51:33 +0300 Message-ID: <878tndjzzu.fsf@dmlp.sw.ru> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2603 Lines: 66 Christoph Hellwig writes: > why? because it is not good thing to truncate page cache and fiew lines later realize that feature is not supported !blk_queue_discard(q) and return ENOTSUPP. Event more: if mode == FALLOC_FL_KEEP_SIZE then we do nothing and return ENOTSUPP unconditionally. IMHO (mode == FALLOC_FL_KEEP_SIZE) is sane API for thin-provision blkdevs to preallocate space in advance. Nobody use it at the moment, but it may be usefull in future. > > On Thu, Apr 06, 2017 at 04:02:49PM +0400, Dmitry Monakhov wrote: >> Signed-off-by: Dmitry Monakhov >> --- >> fs/block_dev.c | 9 ++++----- >> 1 file changed, 4 insertions(+), 5 deletions(-) >> >> diff --git a/fs/block_dev.c b/fs/block_dev.c >> index 2eca00e..f4b13e1 100644 >> --- a/fs/block_dev.c >> +++ b/fs/block_dev.c >> @@ -2075,7 +2075,7 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start, >> { >> struct block_device *bdev = I_BDEV(bdev_file_inode(file)); >> struct request_queue *q = bdev_get_queue(bdev); >> - struct address_space *mapping; >> + struct address_space *mapping = bdev->bd_inode->i_mapping; >> loff_t end = start + len - 1; >> loff_t isize; >> int error; >> @@ -2102,13 +2102,10 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start, >> if ((start | len) & (bdev_logical_block_size(bdev) - 1)) >> return -EINVAL; >> >> - /* Invalidate the page cache, including dirty pages. */ >> - mapping = bdev->bd_inode->i_mapping; >> - truncate_inode_pages_range(mapping, start, end); >> - >> switch (mode) { >> case FALLOC_FL_ZERO_RANGE: >> case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE: >> + truncate_inode_pages_range(mapping, start, end); >> error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, >> GFP_KERNEL, false); >> break; >> @@ -2116,12 +2113,14 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start, >> /* Only punch if the device can do zeroing discard. */ >> if (!blk_queue_discard(q) || !q->limits.discard_zeroes_data) >> return -EOPNOTSUPP; >> + truncate_inode_pages_range(mapping, start, end); >> error = blkdev_issue_discard(bdev, start >> 9, len >> 9, >> GFP_KERNEL, 0); >> break; >> case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE: >> if (!blk_queue_discard(q)) >> return -EOPNOTSUPP; >> + truncate_inode_pages_range(mapping, start, end); >> error = blkdev_issue_discard(bdev, start >> 9, len >> 9, >> GFP_KERNEL, 0); >> break; >> -- >> 2.9.3 >> > ---end quoted text---