From: Dave Jiang Subject: Re: [PATCH v2 2/2] [PATCH] xfs: Close race between direct IO and xfs_break_layouts() Date: Fri, 10 Aug 2018 09:05:26 -0700 Message-ID: References: <153374942137.42241.10539674028265137668.stgit@djiang5-desk3.ch.intel.com> <20180810154809.GD15083@magnolia> <20180810160243.GF4203@magnolia> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: lczerner-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, jack-AlSwsSmVLrQ@public.gmane.org, linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org, linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, zwisler-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tytso-3s7WtUTddSA@public.gmane.org, linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, hch-jcswGhMUV9g@public.gmane.org To: "Darrick J. Wong" Return-path: In-Reply-To: <20180810160243.GF4203@magnolia> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" List-Id: linux-ext4.vger.kernel.org On 08/10/2018 09:02 AM, Darrick J. Wong wrote: > On Fri, Aug 10, 2018 at 08:54:00AM -0700, Dave Jiang wrote: >> >> >> On 08/10/2018 08:48 AM, Darrick J. Wong wrote: >>> On Wed, Aug 08, 2018 at 10:31:40AM -0700, Dave Jiang wrote: >>>> This patch is the duplicate of ross's fix for ext4 for xfs. >>>> >>>> If the refcount of a page is lowered between the time that it is returned >>>> by dax_busy_page() and when the refcount is again checked in >>>> xfs_break_layouts() => ___wait_var_event(), the waiting function >>>> xfs_wait_dax_page() will never be called. This means that >>>> xfs_break_layouts() will still have 'retry' set to false, so we'll stop >>>> looping and never check the refcount of other pages in this inode. >>>> >>>> Instead, always continue looping as long as dax_layout_busy_page() gives us >>>> a page which it found with an elevated refcount. >>>> >>>> Signed-off-by: Dave Jiang >>>> Reviewed-by: Jan Kara >>>> --- >>>> >>>> Sorry resend, forgot to add Jan's reviewed-by. >>>> >>>> v2: >>>> - Rename parameter from did_unlock to retry (Jan) >>>> >>>> fs/xfs/xfs_file.c | 9 ++++----- >>>> 1 file changed, 4 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c >>>> index a3e7767a5715..cd6f0d8c4922 100644 >>>> --- a/fs/xfs/xfs_file.c >>>> +++ b/fs/xfs/xfs_file.c >>>> @@ -721,12 +721,10 @@ xfs_file_write_iter( >>>> >>>> static void >>>> xfs_wait_dax_page( >>>> - struct inode *inode, >>>> - bool *did_unlock) >>>> + struct inode *inode) >>>> { >>>> struct xfs_inode *ip = XFS_I(inode); >>>> >>>> - *did_unlock = true; >>>> xfs_iunlock(ip, XFS_MMAPLOCK_EXCL); >>>> schedule(); >>>> xfs_ilock(ip, XFS_MMAPLOCK_EXCL); >>>> @@ -736,7 +734,7 @@ static int >>>> xfs_break_dax_layouts( >>>> struct inode *inode, >>>> uint iolock, >>>> - bool *did_unlock) >>>> + bool *retry) >>> >>> Uhhh, this hunk doesn't apply. xfs_break_dax_layouts doesn't have an >>> iolock parameter anymore; was this not generated off of xfs for-next? >> >> Sorry. It was generated against 4.18-rc8. I'll respin patch against xfs >> for-next. > > I think it's just a matter of taking the old patch and changing > "did_unlock" to "retry", right? If so, I'll just change that and be > done with this one. :) For the conflict part yes. Thanks! :) > > --D > >>> >>> --D >>> >>>> { >>>> struct page *page; >>>> >>>> @@ -746,9 +744,10 @@ xfs_break_dax_layouts( >>>> if (!page) >>>> return 0; >>>> >>>> + *retry = true; >>>> return ___wait_var_event(&page->_refcount, >>>> atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE, >>>> - 0, 0, xfs_wait_dax_page(inode, did_unlock)); >>>> + 0, 0, xfs_wait_dax_page(inode)); >>>> } >>>> >>>> int >>>> >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in >>>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html