xfs: Close race between direct IO and xfs_break_layouts() (e25ff835) · Commits · 戴 / test

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 <dave.jiang@intel.com> Reviewed-by:

Jan Kara <jack@suse.cz> Reviewed-by:

Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by:

Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/xfs_file.c

+4 −5

Original line number	Original line	Diff line number	Diff line
	@@ -721,12 +721,10 @@ xfs_file_write_iter(

	static void		static void
	xfs_wait_dax_page(		xfs_wait_dax_page(
	struct inode *inode,		struct inode *inode)
	bool *did_unlock)
	{		{
	struct xfs_inode *ip = XFS_I(inode);		struct xfs_inode *ip = XFS_I(inode);

	*did_unlock = true;
	xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);		xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
	schedule();		schedule();
	xfs_ilock(ip, XFS_MMAPLOCK_EXCL);		xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
	@@ -735,7 +733,7 @@ xfs_wait_dax_page(
	static int		static int
	xfs_break_dax_layouts(		xfs_break_dax_layouts(
	struct inode *inode,		struct inode *inode,
	bool *did_unlock)		bool *retry)
	{		{
	struct page *page;		struct page *page;

	@@ -745,9 +743,10 @@ xfs_break_dax_layouts(
	if (!page)		if (!page)
	return 0;		return 0;

			*retry = true;
	return ___wait_var_event(&page->_refcount,		return ___wait_var_event(&page->_refcount,
	atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE,		atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE,
	0, 0, xfs_wait_dax_page(inode, did_unlock));		0, 0, xfs_wait_dax_page(inode));
	}		}

	int		int

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