Commit 8626b67a authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Chandan Babu R
Browse files

xfs: move the dio write relocking out of xfs_ilock_for_iomap 



About half of xfs_ilock_for_iomap deals with a special case for direct
I/O writes to COW files that need to take the ilock exclusively.  Move
this code into the one callers that cares and simplify
xfs_ilock_for_iomap.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Signed-off-by: default avatarChandan Babu R <chandanbabu@kernel.org>
parent 0c7fcdb6

fs/xfs/xfs_iomap.c

+34 −37
Original line number Diff line number Diff line
@@ -717,53 +717,30 @@ imap_needs_cow( 
	return true;

}



/*

 * Extents not yet cached requires exclusive access, don't block for

 * IOMAP_NOWAIT.

 *

 * This is basically an opencoded xfs_ilock_data_map_shared() call, but with

 * support for IOMAP_NOWAIT.

 */

static int

xfs_ilock_for_iomap(

	struct xfs_inode	*ip,

	unsigned		flags,

	unsigned		*lockmode)

{

	unsigned int		mode = *lockmode;

	bool			is_write = flags & (IOMAP_WRITE | IOMAP_ZERO);



	/*

	 * COW writes may allocate delalloc space or convert unwritten COW

	 * extents, so we need to make sure to take the lock exclusively here.

	 */

	if (xfs_is_cow_inode(ip) && is_write)

		mode = XFS_ILOCK_EXCL;



	/*

	 * Extents not yet cached requires exclusive access, don't block.  This

	 * is an opencoded xfs_ilock_data_map_shared() call but with

	 * non-blocking behaviour.

	 */

	if (xfs_need_iread_extents(&ip->i_df)) {

		if (flags & IOMAP_NOWAIT)

			return -EAGAIN;

		mode = XFS_ILOCK_EXCL;

	}



relock:

	if (flags & IOMAP_NOWAIT) {

		if (!xfs_ilock_nowait(ip, mode))

		if (xfs_need_iread_extents(&ip->i_df))

			return -EAGAIN;

		if (!xfs_ilock_nowait(ip, *lockmode))

			return -EAGAIN;

	} else {

		xfs_ilock(ip, mode);

	}



	/*

	 * The reflink iflag could have changed since the earlier unlocked

	 * check, so if we got ILOCK_SHARED for a write and but we're now a

	 * reflink inode we have to switch to ILOCK_EXCL and relock.

	 */

	if (mode == XFS_ILOCK_SHARED && is_write && xfs_is_cow_inode(ip)) {

		xfs_iunlock(ip, mode);

		mode = XFS_ILOCK_EXCL;

		goto relock;

		if (xfs_need_iread_extents(&ip->i_df))

			*lockmode = XFS_ILOCK_EXCL;

		xfs_ilock(ip, *lockmode);

	}



	*lockmode = mode;

	return 0;

}
@@ -801,7 +778,7 @@ xfs_direct_write_iomap_begin( 
	int			nimaps = 1, error = 0;

	bool			shared = false;

	u16			iomap_flags = 0;

	unsigned int		lockmode = XFS_ILOCK_SHARED;

	unsigned int		lockmode;

	u64			seq;



	ASSERT(flags & (IOMAP_WRITE | IOMAP_ZERO));
@@ -817,10 +794,30 @@ xfs_direct_write_iomap_begin( 
	if (offset + length > i_size_read(inode))

		iomap_flags |= IOMAP_F_DIRTY;



	/*

	 * COW writes may allocate delalloc space or convert unwritten COW

	 * extents, so we need to make sure to take the lock exclusively here.

	 */

	if (xfs_is_cow_inode(ip))

		lockmode = XFS_ILOCK_EXCL;

	else

		lockmode = XFS_ILOCK_SHARED;



relock:

	error = xfs_ilock_for_iomap(ip, flags, &lockmode);

	if (error)

		return error;



	/*

	 * The reflink iflag could have changed since the earlier unlocked

	 * check, check if it again and relock if needed.

	 */

	if (xfs_is_cow_inode(ip) && lockmode == XFS_ILOCK_SHARED) {

		xfs_iunlock(ip, lockmode);

		lockmode = XFS_ILOCK_EXCL;

		goto relock;

	}



	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,

			       &nimaps, 0);

	if (error)