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From: Dave Chinner <david@fromorbit.com>
To: xfs@oss.sgi.com
Subject: [PATCH 07/18] xfs: introduced uncached buffer read primitve
Date: Fri, 24 Sep 2010 22:31:05 +1000	[thread overview]
Message-ID: <1285331476-23015-8-git-send-email-david@fromorbit.com> (raw)
In-Reply-To: <1285331476-23015-1-git-send-email-david@fromorbit.com>

From: Dave Chinner <dchinner@redhat.com>

To avoid the need to use cached buffers for single-shot or buffers
cached at the filesystem level, introduce a new buffer read
primitive that bypasses the cache an reads directly from disk.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
---
 fs/xfs/linux-2.6/xfs_buf.c |   34 ++++++++++++++++++++++++++++++++++
 fs/xfs/linux-2.6/xfs_buf.h |    3 +++
 2 files changed, 37 insertions(+), 0 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index eca945b..22c7bff 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -638,6 +638,40 @@ xfs_buf_readahead(
 	xfs_buf_read(target, ioff, isize, flags);
 }
 
+/*
+ * Read an uncached buffer from disk. Allocates and returns a locked
+ * buffer containing the disk contents or nothing.
+ */
+struct xfs_buf *
+xfs_buf_read_uncached(
+	struct xfs_mount	*mp,
+	struct xfs_buftarg	*target,
+	xfs_daddr_t		daddr,
+	size_t			length,
+	int			flags)
+{
+	xfs_buf_t		*bp;
+	int			error;
+
+	bp = xfs_buf_get_uncached(target, length, flags);
+	if (!bp)
+		return NULL;
+
+	/* set up the buffer for a read IO */
+	xfs_buf_lock(bp);
+	XFS_BUF_SET_ADDR(bp, daddr);
+	XFS_BUF_READ(bp);
+	XFS_BUF_BUSY(bp);
+
+	xfsbdstrat(mp, bp);
+	error = xfs_iowait(bp);
+	if (error || bp->b_error) {
+		xfs_buf_relse(bp);
+		return NULL;
+	}
+	return bp;
+}
+
 xfs_buf_t *
 xfs_buf_get_empty(
 	size_t			len,
diff --git a/fs/xfs/linux-2.6/xfs_buf.h b/fs/xfs/linux-2.6/xfs_buf.h
index fb30447..57eedc7 100644
--- a/fs/xfs/linux-2.6/xfs_buf.h
+++ b/fs/xfs/linux-2.6/xfs_buf.h
@@ -218,6 +218,9 @@ extern int xfs_buf_associate_memory(xfs_buf_t *, void *, size_t);
 extern void xfs_buf_hold(xfs_buf_t *);
 extern void xfs_buf_readahead(xfs_buftarg_t *, xfs_off_t, size_t,
 				xfs_buf_flags_t);
+struct xfs_buf *xfs_buf_read_uncached(struct xfs_mount *mp,
+				struct xfs_buftarg *target,
+				xfs_daddr_t daddr, size_t length, int flags);
 
 /* Releasing Buffers */
 extern void xfs_buf_free(xfs_buf_t *);
-- 
1.7.1

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  parent reply	other threads:[~2010-09-24 12:30 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-24 12:30 [PATCH 0/18] xfs: metadata scalability V3 Dave Chinner
2010-09-24 12:30 ` [PATCH 01/18] xfs: force background CIL push under sustained load Dave Chinner
2010-09-24 12:31 ` [PATCH 02/18] xfs: reduce the number of CIL lock round trips during commit Dave Chinner
2010-09-24 12:31 ` [PATCH 03/18] xfs: remove debug assert for per-ag reference counting Dave Chinner
2010-09-24 12:31 ` [PATCH 04/18] xfs: lockless per-ag lookups Dave Chinner
2010-09-24 12:31 ` [PATCH 05/18] xfs: don't use vfs writeback for pure metadata modifications Dave Chinner
2010-09-25 23:42   ` Christoph Hellwig
2010-09-27  1:09     ` Dave Chinner
2010-09-24 12:31 ` [PATCH 06/18] xfs: rename xfs_buf_get_nodaddr to be more appropriate Dave Chinner
2010-09-24 12:31 ` Dave Chinner [this message]
2010-09-24 12:31 ` [PATCH 08/18] xfs: store xfs_mount in the buftarg instead of in the xfs_buf Dave Chinner
2010-09-24 12:31 ` [PATCH 09/18] xfs: kill XBF_FS_MANAGED buffers Dave Chinner
2010-09-24 12:31 ` [PATCH 10/18] xfs: use unhashed buffers for size checks Dave Chinner
2010-09-24 12:31 ` [PATCH 11/18] xfs: remove buftarg hash for external devices Dave Chinner
2010-09-24 12:31 ` [PATCH 12/18] xfs: split inode AG walking into separate code for reclaim Dave Chinner
2010-09-24 12:31 ` [PATCH 13/18] xfs: split out inode walk inode grabbing Dave Chinner
2010-09-25 16:31   ` Christoph Hellwig
2010-09-24 12:31 ` [PATCH 14/18] xfs: implement batched inode lookups for AG walking Dave Chinner
2010-09-25 16:32   ` Christoph Hellwig
2010-09-24 12:31 ` [PATCH 15/18] xfs: batch inode reclaim lookup Dave Chinner
2010-09-24 12:31 ` [PATCH 16/18] xfs: serialise inode reclaim within an AG Dave Chinner
2010-09-25 23:49   ` Christoph Hellwig
2010-09-27  0:56     ` Dave Chinner
2010-09-24 12:31 ` [PATCH 17/18] xfs: convert buffer cache hash to rbtree Dave Chinner
2010-09-24 12:31 ` [PATCH 18/18] xfs: pack xfs_buf structure more tightly Dave Chinner
  -- strict thread matches above, loose matches on Subject: below --
2010-09-27  1:47 [PATCH 0/18] xfs: metadata scalability V4 Dave Chinner
2010-09-27  1:47 ` [PATCH 07/18] xfs: introduced uncached buffer read primitve Dave Chinner

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