From: Dave Jiang Subject: [PATCH v2 2/2] [PATCH] xfs: Close race between direct IO and xfs_break_layouts() Date: Wed, 08 Aug 2018 10:31:40 -0700 Message-ID: <153374942137.42241.10539674028265137668.stgit@djiang5-desk3.ch.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org, linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lczerner-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, hch-jcswGhMUV9g@public.gmane.org To: tytso-3s7WtUTddSA@public.gmane.org, darrick.wong-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, jack-AlSwsSmVLrQ@public.gmane.org, zwisler-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org Return-path: 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 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) { 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