* [PATCH 05/21] refactor xfs_btree_readahead
@ 2008-07-29 19:30 Christoph Hellwig
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From: Christoph Hellwig @ 2008-07-29 19:30 UTC (permalink / raw)
To: xfs
[-- Attachment #1: xfs-btree-readahead-refactor --]
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From: Dave Chinner <dgc@sgi.com>
Refactor xfs_btree_readahead to make it more readable:
(a) remove the inline xfs_btree_readahead wrapper and move all checks out
of line into the main routine.
(b) factor out helpers for short/long form btrees
(c) move check for root in inodes from the callers into xfs_btree_readahead
[hch: split out from a big patch and minor cleanups]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Index: linux-2.6-xfs/fs/xfs/xfs_btree.c
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_btree.c 2008-07-27 13:06:45.000000000 +0200
+++ linux-2.6-xfs/fs/xfs/xfs_btree.c 2008-07-28 17:41:41.000000000 +0200
@@ -709,66 +709,85 @@ xfs_btree_reada_bufs(
xfs_baread(mp->m_ddev_targp, d, mp->m_bsize * count);
}
+STATIC int
+xfs_btree_readahead_lblock(
+ struct xfs_btree_cur *cur,
+ int lr,
+ struct xfs_btree_lblock *lb)
+{
+ int rval = 0;
+ xfs_fsblock_t left = be64_to_cpu(lb->bb_leftsib);
+ xfs_fsblock_t right = be64_to_cpu(lb->bb_rightsib);
+
+ if ((lr & XFS_BTCUR_LEFTRA) && left != NULLDFSBNO) {
+ xfs_btree_reada_bufl(cur->bc_mp, left, 1);
+ rval++;
+ }
+
+ if ((lr & XFS_BTCUR_RIGHTRA) && right != NULLDFSBNO) {
+ xfs_btree_reada_bufl(cur->bc_mp, right, 1);
+ rval++;
+ }
+
+ return rval;
+}
+
+STATIC int
+xfs_btree_readahead_sblock(
+ struct xfs_btree_cur *cur,
+ int lr,
+ struct xfs_btree_sblock *sb)
+{
+ int rval = 0;
+ xfs_agblock_t left = be32_to_cpu(sb->bb_leftsib);
+ xfs_agblock_t right = be32_to_cpu(sb->bb_rightsib);
+
+
+ if ((lr & XFS_BTCUR_LEFTRA) && left != NULLAGBLOCK) {
+ xfs_btree_reada_bufs(cur->bc_mp, cur->bc_private.a.agno,
+ left, 1);
+ rval++;
+ }
+
+ if ((lr & XFS_BTCUR_RIGHTRA) && right != NULLAGBLOCK) {
+ xfs_btree_reada_bufs(cur->bc_mp, cur->bc_private.a.agno,
+ right, 1);
+ rval++;
+ }
+
+ return rval;
+}
+
/*
* Read-ahead btree blocks, at the given level.
* Bits in lr are set from XFS_BTCUR_{LEFT,RIGHT}RA.
*/
int
-xfs_btree_readahead_core(
- xfs_btree_cur_t *cur, /* btree cursor */
+xfs_btree_readahead(
+ struct xfs_btree_cur *cur, /* btree cursor */
int lev, /* level in btree */
int lr) /* left/right bits */
{
- xfs_alloc_block_t *a;
- xfs_bmbt_block_t *b;
- xfs_inobt_block_t *i;
- int rval = 0;
+ struct xfs_buf *bp;
+
+ /*
+ * No readahead needed if we are at the root level and the
+ * btree root is stored in the inode.
+ */
+ if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
+ (lev == cur->bc_nlevels - 1))
+ return 0;
+
+ if ((cur->bc_ra[lev] | lr) == cur->bc_ra[lev])
+ return 0;
- ASSERT(cur->bc_bufs[lev] != NULL);
cur->bc_ra[lev] |= lr;
- switch (cur->bc_btnum) {
- case XFS_BTNUM_BNO:
- case XFS_BTNUM_CNT:
- a = XFS_BUF_TO_ALLOC_BLOCK(cur->bc_bufs[lev]);
- if ((lr & XFS_BTCUR_LEFTRA) && be32_to_cpu(a->bb_leftsib) != NULLAGBLOCK) {
- xfs_btree_reada_bufs(cur->bc_mp, cur->bc_private.a.agno,
- be32_to_cpu(a->bb_leftsib), 1);
- rval++;
- }
- if ((lr & XFS_BTCUR_RIGHTRA) && be32_to_cpu(a->bb_rightsib) != NULLAGBLOCK) {
- xfs_btree_reada_bufs(cur->bc_mp, cur->bc_private.a.agno,
- be32_to_cpu(a->bb_rightsib), 1);
- rval++;
- }
- break;
- case XFS_BTNUM_BMAP:
- b = XFS_BUF_TO_BMBT_BLOCK(cur->bc_bufs[lev]);
- if ((lr & XFS_BTCUR_LEFTRA) && be64_to_cpu(b->bb_leftsib) != NULLDFSBNO) {
- xfs_btree_reada_bufl(cur->bc_mp, be64_to_cpu(b->bb_leftsib), 1);
- rval++;
- }
- if ((lr & XFS_BTCUR_RIGHTRA) && be64_to_cpu(b->bb_rightsib) != NULLDFSBNO) {
- xfs_btree_reada_bufl(cur->bc_mp, be64_to_cpu(b->bb_rightsib), 1);
- rval++;
- }
- break;
- case XFS_BTNUM_INO:
- i = XFS_BUF_TO_INOBT_BLOCK(cur->bc_bufs[lev]);
- if ((lr & XFS_BTCUR_LEFTRA) && be32_to_cpu(i->bb_leftsib) != NULLAGBLOCK) {
- xfs_btree_reada_bufs(cur->bc_mp, cur->bc_private.a.agno,
- be32_to_cpu(i->bb_leftsib), 1);
- rval++;
- }
- if ((lr & XFS_BTCUR_RIGHTRA) && be32_to_cpu(i->bb_rightsib) != NULLAGBLOCK) {
- xfs_btree_reada_bufs(cur->bc_mp, cur->bc_private.a.agno,
- be32_to_cpu(i->bb_rightsib), 1);
- rval++;
- }
- break;
- default:
- ASSERT(0);
- }
- return rval;
+ bp = cur->bc_bufs[lev];
+
+ if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
+ return xfs_btree_readahead_lblock(cur, lr,
+ XFS_BUF_TO_LBLOCK(bp));
+ return xfs_btree_readahead_sblock(cur, lr, XFS_BUF_TO_SBLOCK(bp));
}
/*
Index: linux-2.6-xfs/fs/xfs/xfs_btree.h
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_btree.h 2008-07-27 13:06:45.000000000 +0200
+++ linux-2.6-xfs/fs/xfs/xfs_btree.h 2008-07-28 17:37:23.000000000 +0200
@@ -429,23 +429,10 @@ xfs_btree_reada_bufs(
* Bits in lr are set from XFS_BTCUR_{LEFT,RIGHT}RA.
*/
int /* readahead block count */
-xfs_btree_readahead_core(
- xfs_btree_cur_t *cur, /* btree cursor */
- int lev, /* level in btree */
- int lr); /* left/right bits */
-
-static inline int /* readahead block count */
xfs_btree_readahead(
xfs_btree_cur_t *cur, /* btree cursor */
int lev, /* level in btree */
- int lr) /* left/right bits */
-{
- if ((cur->bc_ra[lev] | lr) == cur->bc_ra[lev])
- return 0;
-
- return xfs_btree_readahead_core(cur, lev, lr);
-}
-
+ int lr); /* left/right bits */
/*
* Set the buffer for level "lev" in the cursor to bp, releasing
Index: linux-2.6-xfs/fs/xfs/xfs_bmap_btree.c
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_bmap_btree.c 2008-07-27 13:06:45.000000000 +0200
+++ linux-2.6-xfs/fs/xfs/xfs_bmap_btree.c 2008-07-28 17:37:21.000000000 +0200
@@ -1721,8 +1721,9 @@ xfs_bmbt_decrement(
XFS_BMBT_TRACE_CURSOR(cur, ENTRY);
XFS_BMBT_TRACE_ARGI(cur, level);
ASSERT(level < cur->bc_nlevels);
- if (level < cur->bc_nlevels - 1)
- xfs_btree_readahead(cur, level, XFS_BTCUR_LEFTRA);
+
+ xfs_btree_readahead(cur, level, XFS_BTCUR_LEFTRA);
+
if (--cur->bc_ptrs[level] > 0) {
XFS_BMBT_TRACE_CURSOR(cur, EXIT);
*stat = 1;
@@ -1743,8 +1744,7 @@ xfs_bmbt_decrement(
for (lev = level + 1; lev < cur->bc_nlevels; lev++) {
if (--cur->bc_ptrs[lev] > 0)
break;
- if (lev < cur->bc_nlevels - 1)
- xfs_btree_readahead(cur, lev, XFS_BTCUR_LEFTRA);
+ xfs_btree_readahead(cur, lev, XFS_BTCUR_LEFTRA);
}
if (lev == cur->bc_nlevels) {
XFS_BMBT_TRACE_CURSOR(cur, EXIT);
@@ -1995,8 +1995,8 @@ xfs_bmbt_increment(
XFS_BMBT_TRACE_CURSOR(cur, ENTRY);
XFS_BMBT_TRACE_ARGI(cur, level);
ASSERT(level < cur->bc_nlevels);
- if (level < cur->bc_nlevels - 1)
- xfs_btree_readahead(cur, level, XFS_BTCUR_RIGHTRA);
+
+ xfs_btree_readahead(cur, level, XFS_BTCUR_RIGHTRA);
block = xfs_bmbt_get_block(cur, level, &bp);
#ifdef DEBUG
if ((error = xfs_btree_check_lblock(cur, block, level, bp))) {
@@ -2024,8 +2024,7 @@ xfs_bmbt_increment(
#endif
if (++cur->bc_ptrs[lev] <= be16_to_cpu(block->bb_numrecs))
break;
- if (lev < cur->bc_nlevels - 1)
- xfs_btree_readahead(cur, lev, XFS_BTCUR_RIGHTRA);
+ xfs_btree_readahead(cur, lev, XFS_BTCUR_RIGHTRA);
}
if (lev == cur->bc_nlevels) {
XFS_BMBT_TRACE_CURSOR(cur, EXIT);
--
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