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From: Dave Chinner <david@fromorbit.com>
To: xfs@oss.sgi.com
Subject: [PATCH 04/12] xfs: add compound buffer get and read interfaces
Date: Wed,  7 Dec 2011 17:18:15 +1100	[thread overview]
Message-ID: <1323238703-13198-5-git-send-email-david@fromorbit.com> (raw)
In-Reply-To: <1323238703-13198-1-git-send-email-david@fromorbit.com>

From: Dave Chinner <dchinner@redhat.com>

For a compound buffer, we need to have some way of specifying all
the extents that need to be part of the buffer in one structure. The
dabuf code gets this directly from xfs_bmapi() in the form of an
xfs_bmbt_irec array. It makes sense to simply use this as the method
of transferring the information to the compound buffer get and read
functions that are responsible for building such buffers.

Implement the get and read compound buffer functions using this
interface. Initially only support a single irec map to simplify the
initial implementation. Support for multiple records will be added
in future commits.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_buf.c |   78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_buf.h |   10 +++++++
 2 files changed, 88 insertions(+), 0 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 152e855..aebe954 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -40,6 +40,8 @@
 #include "xfs_ag.h"
 #include "xfs_mount.h"
 #include "xfs_trace.h"
+#include "xfs_bit.h"
+#include "xfs_bmap_btree.h"
 
 static kmem_zone_t *xfs_buf_zone;
 STATIC int xfsbufd(void *);
@@ -670,6 +672,82 @@ xfs_buf_readahead(
 }
 
 /*
+ * XXX: only supports a single map for now
+ */
+struct xfs_buf *
+xfs_buf_get_irec(
+	struct xfs_buftarg	*target,
+	struct xfs_bmbt_irec	*map,
+	int			nmaps,
+	xfs_buf_flags_t		flags)
+{
+	xfs_daddr_t		blkno;
+	size_t			numblks;
+	struct xfs_buf		*bp;
+
+	ASSERT_ALWAYS(nmaps == 1);
+
+	blkno = XFS_FSB_TO_DADDR(target->bt_mount, map->br_startblock);
+	numblks = XFS_FSB_TO_BB(target->bt_mount, map->br_blockcount);
+
+	bp = xfs_buf_get(target, blkno, numblks, flags);
+
+	return bp;
+}
+
+struct xfs_buf *
+xfs_buf_read_irec(
+	struct xfs_buftarg	*target,
+	struct xfs_bmbt_irec	*map,
+	int			nmaps,
+	xfs_buf_flags_t		flags)
+{
+	xfs_buf_t		*bp;
+
+	flags |= XBF_READ;
+
+	bp = xfs_buf_get_irec(target, map, nmaps, flags);
+	if (bp) {
+		trace_xfs_buf_read(bp, flags, _RET_IP_);
+
+		if (!XFS_BUF_ISDONE(bp)) {
+			XFS_STATS_INC(xb_get_read);
+			_xfs_buf_read(bp, flags);
+		} else if (flags & XBF_ASYNC) {
+			/*
+			 * Read ahead call which is already satisfied,
+			 * drop the buffer
+			 */
+			goto no_buffer;
+		} else {
+			/* We do not want read in the flags */
+			bp->b_flags &= ~XBF_READ;
+		}
+	}
+
+	return bp;
+
+ no_buffer:
+	if (flags & (XBF_LOCK | XBF_TRYLOCK))
+		xfs_buf_unlock(bp);
+	xfs_buf_rele(bp);
+	return NULL;
+}
+
+void
+xfs_buf_readahead_irec(
+	struct xfs_buftarg	*target,
+	struct xfs_bmbt_irec	*map,
+	int			nmaps)
+{
+	if (bdi_read_congested(target->bt_bdi))
+		return;
+
+	xfs_buf_read_irec(target, map, nmaps,
+		     XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD|XBF_DONT_BLOCK);
+}
+
+/*
  * Read an uncached buffer from disk. Allocates and returns a locked
  * buffer containing the disk contents or nothing.
  */
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 1a3367e..e3cbd73 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -122,6 +122,7 @@ typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);
 
 #define XB_PAGES	2
 
+struct xfs_bmbt_irec;
 struct xfs_buf_vec {
 	xfs_daddr_t		bv_bn;	/* block number for I/O */
 	size_t			bv_len;	/* size of I/O */
@@ -189,6 +190,15 @@ struct xfs_buf *xfs_buf_read(struct xfs_buftarg *target, xfs_daddr_t blkno,
 void xfs_buf_readahead(struct xfs_buftarg *target, xfs_daddr_t blkno,
 				size_t numblks);
 
+struct xfs_buf *xfs_buf_get_irec(struct xfs_buftarg *target,
+				struct xfs_bmbt_irec *map, int nmaps,
+				xfs_buf_flags_t flags);
+struct xfs_buf *xfs_buf_read_irec(struct xfs_buftarg *target,
+				struct xfs_bmbt_irec *map, int nmaps,
+				xfs_buf_flags_t flags);
+void xfs_buf_readahead_irec(struct xfs_buftarg *target,
+				struct xfs_bmbt_irec *map, int nmaps);
+
 struct xfs_buf *xfs_buf_get_empty(struct xfs_buftarg *target, size_t numblks);
 struct xfs_buf *xfs_buf_alloc(struct xfs_buftarg *target, xfs_daddr_t blkno,
 				size_t numblks, xfs_buf_flags_t flags);
-- 
1.7.5.4

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  parent reply	other threads:[~2011-12-07  6:18 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-12-07  6:18 [RFC, PATCH 0/12] xfs: compound buffers for directory blocks Dave Chinner
2011-12-07  6:18 ` [PATCH 01/12] xfs: remove remaining scraps of struct xfs_iomap Dave Chinner
2011-12-08 16:02   ` Christoph Hellwig
2011-12-07  6:18 ` [PATCH 02/12] xfs: clean up buffer get/read call API Dave Chinner
2011-12-08 16:07   ` Christoph Hellwig
2011-12-07  6:18 ` [PATCH 03/12] xfs: introduce a compound buffer construct Dave Chinner
2011-12-17 23:11   ` Christoph Hellwig
2011-12-07  6:18 ` Dave Chinner [this message]
2011-12-17 23:14   ` [PATCH 04/12] xfs: add compound buffer get and read interfaces Christoph Hellwig
2011-12-07  6:18 ` [PATCH 05/12] xfs: add irec interfaces to xfs_trans_buf_get/read Dave Chinner
2011-12-07  6:18 ` [PATCH 06/12] xfs: convert xfs_da_do_buf to use irec buffer interface Dave Chinner
2011-12-07  6:18 ` [PATCH 07/12] xfs: switch the buffer get/read API to use irec methods Dave Chinner
2011-12-07  6:18 ` [PATCH 08/12] xfs: support multiple irec maps in buffer code Dave Chinner
2011-12-07  6:18 ` [PATCH 09/12] xfs: support compund buffers in buf_item logging Dave Chinner
2011-12-07  6:18 ` [PATCH 10/12] xfs: use multiple irec xfs buf support in dabuf Dave Chinner
2011-12-07  6:18 ` [PATCH 11/12] xfs: remove struct xfs_dabuf and infrastructure Dave Chinner
2011-12-17 23:30   ` Christoph Hellwig
2011-12-07  6:18 ` [PATCH 12/12] xfs: remove duplication in transaction buffer operations Dave Chinner
2011-12-17 23:32   ` Christoph Hellwig
2011-12-07  6:35 ` [RFC, PATCH 0/12] xfs: compound buffers for directory blocks Christoph Hellwig
2011-12-07  9:23   ` Dave Chinner
2011-12-14 18:33 ` Christoph Hellwig
2011-12-18 23:01   ` Dave Chinner

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