From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: [PATCH 1/3] block: invalidate the page cache when issuing BLKZEROOUT. Date: Mon, 20 Jun 2016 14:35:29 +0200 Message-ID: <7589fc01-a000-a912-f9b5-cf099cc2d27a@acm.org> References: <146612624734.12764.4316680863289411106.stgit@birch.djwong.org> <146612625412.12764.6647932282740152837.stgit@birch.djwong.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <146612625412.12764.6647932282740152837.stgit@birch.djwong.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: "Darrick J. Wong" , "axboe@kernel.dk" Cc: "hch@infradead.org" , "tytso@mit.edu" , "martin.petersen@oracle.com" , "snitzer@redhat.com" , "linux-api@vger.kernel.org" , "bfoster@redhat.com" , "xfs@oss.sgi.com" , "linux-block@vger.kernel.org" , "dm-devel@redhat.com" , "linux-fsdevel@vger.kernel.org" , Christoph Hellwig List-Id: linux-api@vger.kernel.org On 06/17/2016 03:18 AM, Darrick J. Wong wrote: > Invalidate the page cache (as a regular O_DIRECT write would do) to avoid > returning stale cache contents at a later time. > > v5: Refactor the 4.4 refactoring of the ioctl code into separate functions. > Split the page invalidation and the new ioctl into separate patches. > > Signed-off-by: Darrick J. Wong > Reviewed-by: Christoph Hellwig > --- > block/ioctl.c | 29 +++++++++++++++++++++++------ > 1 file changed, 23 insertions(+), 6 deletions(-) > > > diff --git a/block/ioctl.c b/block/ioctl.c > index ed2397f..d001f52 100644 > --- a/block/ioctl.c > +++ b/block/ioctl.c > @@ -225,7 +225,9 @@ static int blk_ioctl_zeroout(struct block_device *bdev, fmode_t mode, > unsigned long arg) > { > uint64_t range[2]; > - uint64_t start, len; > + struct address_space *mapping; > + uint64_t start, end, len; > + int ret; > > if (!(mode & FMODE_WRITE)) > return -EBADF; > @@ -235,18 +237,33 @@ static int blk_ioctl_zeroout(struct block_device *bdev, fmode_t mode, > > start = range[0]; > len = range[1]; > + end = start + len - 1; > > if (start & 511) > return -EINVAL; > if (len & 511) > return -EINVAL; > - start >>= 9; > - len >>= 9; > - > - if (start + len > (i_size_read(bdev->bd_inode) >> 9)) > + if (end >= (uint64_t)i_size_read(bdev->bd_inode)) > + return -EINVAL; > + if (end < start) > return -EINVAL; > > - return blkdev_issue_zeroout(bdev, start, len, GFP_KERNEL, false); > + /* Invalidate the page cache, including dirty pages */ > + mapping = bdev->bd_inode->i_mapping; > + truncate_inode_pages_range(mapping, start, end); > + > + ret = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, GFP_KERNEL, > + false); > + if (ret) > + return ret; > + > + /* > + * Invalidate again; if someone wandered in and dirtied a page, > + * the caller will be given -EBUSY. > + */ > + return invalidate_inode_pages2_range(mapping, > + start >> PAGE_SHIFT, > + end >> PAGE_SHIFT); > } Hello Darrick, Maybe this has already been discussed, but anyway: in the POSIX spec (http://pubs.opengroup.org/onlinepubs/9699919799/functions/write.html) I found the following: "This volume of POSIX.1-2008 does not specify behavior of concurrent writes to a file from multiple processes. Applications should use some form of concurrency control." Do we really need the invalidate_inode_pages2_range() call? Thanks, Bart. _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs