Commit efc5f7a9 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Carlos Maiolino
Browse files

xfs: decouple buffer readahead from the normal buffer read path 



xfs_buf_readahead_map is the only caller of xfs_buf_read_map and thus
_xfs_buf_read that is not synchronous.  Split it from xfs_buf_read_map
so that the asynchronous path is self-contained and the now purely
synchronous xfs_buf_read_map / _xfs_buf_read implementation can be
simplified.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Signed-off-by: default avatarCarlos Maiolino <cem@kernel.org>
parent 4b90de5b

fs/xfs/xfs_buf.c

+20 −21
Original line number Diff line number Diff line
@@ -794,18 +794,13 @@ xfs_buf_get_map( 


int

_xfs_buf_read(

	struct xfs_buf		*bp,

	xfs_buf_flags_t		flags)

	struct xfs_buf		*bp)

{

	ASSERT(!(flags & XBF_WRITE));

	ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);



	bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD | XBF_DONE);

	bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);



	bp->b_flags |= XBF_READ;

	xfs_buf_submit(bp);

	if (flags & XBF_ASYNC)

		return 0;

	return xfs_buf_iowait(bp);

}
@@ -857,6 +852,8 @@ xfs_buf_read_map( 
	struct xfs_buf		*bp;

	int			error;



	ASSERT(!(flags & (XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD)));



	flags |= XBF_READ;

	*bpp = NULL;
@@ -870,21 +867,11 @@ xfs_buf_read_map( 
		/* Initiate the buffer read and wait. */

		XFS_STATS_INC(target->bt_mount, xb_get_read);

		bp->b_ops = ops;

		error = _xfs_buf_read(bp, flags);



		/* Readahead iodone already dropped the buffer, so exit. */

		if (flags & XBF_ASYNC)

			return 0;

		error = _xfs_buf_read(bp);

	} else {

		/* Buffer already read; all we need to do is check it. */

		error = xfs_buf_reverify(bp, ops);



		/* Readahead already finished; drop the buffer and exit. */

		if (flags & XBF_ASYNC) {

			xfs_buf_relse(bp);

			return 0;

		}



		/* We do not want read in the flags */

		bp->b_flags &= ~XBF_READ;

		ASSERT(bp->b_ops != NULL || ops == NULL);
@@ -936,6 +923,7 @@ xfs_buf_readahead_map( 
	int			nmaps,

	const struct xfs_buf_ops *ops)

{

	const xfs_buf_flags_t	flags = XBF_READ | XBF_ASYNC | XBF_READ_AHEAD;

	struct xfs_buf		*bp;



	/*
@@ -945,9 +933,20 @@ xfs_buf_readahead_map( 
	if (xfs_buftarg_is_mem(target))

		return;



	xfs_buf_read_map(target, map, nmaps,

		     XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD, &bp, ops,

		     __this_address);

	if (xfs_buf_get_map(target, map, nmaps, flags | XBF_TRYLOCK, &bp))

		return;

	trace_xfs_buf_readahead(bp, 0, _RET_IP_);



	if (bp->b_flags & XBF_DONE) {

		xfs_buf_reverify(bp, ops);

		xfs_buf_relse(bp);

		return;

	}

	XFS_STATS_INC(target->bt_mount, xb_get_read);

	bp->b_ops = ops;

	bp->b_flags &= ~(XBF_WRITE | XBF_DONE);

	bp->b_flags |= flags;

	xfs_buf_submit(bp);

}



/*

fs/xfs/xfs_buf.h

+1 −1
Original line number Diff line number Diff line
@@ -291,7 +291,7 @@ int xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks, 
int xfs_buf_read_uncached(struct xfs_buftarg *target, xfs_daddr_t daddr,

		size_t numblks, xfs_buf_flags_t flags, struct xfs_buf **bpp,

		const struct xfs_buf_ops *ops);

int _xfs_buf_read(struct xfs_buf *bp, xfs_buf_flags_t flags);

int _xfs_buf_read(struct xfs_buf *bp);

void xfs_buf_hold(struct xfs_buf *bp);



/* Releasing Buffers */

fs/xfs/xfs_log_recover.c

+1 −1
Original line number Diff line number Diff line
@@ -3380,7 +3380,7 @@ xlog_do_recover( 
	 */

	xfs_buf_lock(bp);

	xfs_buf_hold(bp);

	error = _xfs_buf_read(bp, XBF_READ);

	error = _xfs_buf_read(bp);

	if (error) {

		if (!xlog_is_shutdown(log)) {

			xfs_buf_ioerror_alert(bp, __this_address);

fs/xfs/xfs_trace.h

+1 −0
Original line number Diff line number Diff line
@@ -593,6 +593,7 @@ DEFINE_EVENT(xfs_buf_flags_class, name, \ 
DEFINE_BUF_FLAGS_EVENT(xfs_buf_find);

DEFINE_BUF_FLAGS_EVENT(xfs_buf_get);

DEFINE_BUF_FLAGS_EVENT(xfs_buf_read);

DEFINE_BUF_FLAGS_EVENT(xfs_buf_readahead);



TRACE_EVENT(xfs_buf_ioerror,

	TP_PROTO(struct xfs_buf *bp, int error, xfs_failaddr_t caller_ip),