[XFS] implement generic xfs_btree_increment

From: Dave Chinner <dgc@sgi.com>

Because this is the first major generic btree routine this patch includes
some infrastrucure, first a few routines to deal with a btree block that
can be either in short or long form, second xfs_btree_read_buf_block,
which is the new central routine to read a btree block given a cursor, and
third the new xfs_btree_ptr_addr routine to calculate the address for a
given btree pointer record.

[hch: split out from bigger patch and minor adaptions]

SGI-PV: 985583

SGI-Modid: xfs-linux-melb:xfs-kern:32190a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Bill O'Donnell <billodo@sgi.com>
Signed-off-by: David Chinner <david@fromorbit.com>

1 files changed, 4 insertions, 95 deletions

diff --git a/fs/xfs/xfs_alloc_btree.c b/fs/xfs/xfs_alloc_btree.c
index 9e2421c31a36..febc2d5ea295 100644
--- a/fs/xfs/xfs_alloc_btree.c
+++ b/fs/xfs/xfs_alloc_btree.c
@@ -303,7 +303,7 @@ xfs_alloc_delrec(
                  */
                 i = xfs_btree_lastrec(tcur, level);
                 XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
-                if ((error = xfs_alloc_increment(tcur, level, &i)))
+                if ((error = xfs_btree_increment(tcur, level, &i)))
                         goto error0;
                 XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
                 i = xfs_btree_lastrec(tcur, level);
@@ -517,7 +517,7 @@ xfs_alloc_delrec(
          * us, increment the cursor at that level.
          */
         else if (level + 1 < cur->bc_nlevels &&
-                 (error = xfs_alloc_increment(cur, level + 1, &i)))
+                 (error = xfs_btree_increment(cur, level + 1, &i)))
                 return error;
         /*
          * Fix up the number of records in the surviving block.
@@ -1134,7 +1134,7 @@ xfs_alloc_lookup(
                         int     i;
 
                         cur->bc_ptrs[0] = keyno;
-                        if ((error = xfs_alloc_increment(cur, 0, &i)))
+                        if ((error = xfs_btree_increment(cur, 0, &i)))
                                 return error;
                         XFS_WANT_CORRUPTED_RETURN(i == 1);
                         *stat = 1;
@@ -1570,7 +1570,7 @@ xfs_alloc_rshift(
                 return error;
         i = xfs_btree_lastrec(tcur, level);
         XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
-        if ((error = xfs_alloc_increment(tcur, level, &i)) ||
+        if ((error = xfs_btree_increment(tcur, level, &i)) ||
             (error = xfs_alloc_updkey(tcur, rkp, level + 1)))
                 goto error0;
         xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
@@ -1943,97 +1943,6 @@ xfs_alloc_get_rec(
 }
 
 /*
- * Increment cursor by one record at the level.
- * For nonzero levels the leaf-ward information is untouched.
- */
-int                                     /* error */
-xfs_alloc_increment(
-        xfs_btree_cur_t         *cur,   /* btree cursor */
-        int                     level,  /* level in btree, 0 is leaf */
-        int                     *stat)  /* success/failure */
-{
-        xfs_alloc_block_t       *block; /* btree block */
-        xfs_buf_t               *bp;    /* tree block buffer */
-        int                     error;  /* error return value */
-        int                     lev;    /* btree level */
-
-        ASSERT(level < cur->bc_nlevels);
-        /*
-         * Read-ahead to the right at this level.
-         */
-        xfs_btree_readahead(cur, level, XFS_BTCUR_RIGHTRA);
-        /*
-         * Get a pointer to the btree block.
-         */
-        bp = cur->bc_bufs[level];
-        block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-#ifdef DEBUG
-        if ((error = xfs_btree_check_sblock(cur, block, level, bp)))
-                return error;
-#endif
-        /*
-         * Increment the ptr at this level.  If we're still in the block
-         * then we're done.
-         */
-        if (++cur->bc_ptrs[level] <= be16_to_cpu(block->bb_numrecs)) {
-                *stat = 1;
-                return 0;
-        }
-        /*
-         * If we just went off the right edge of the tree, return failure.
-         */
-        if (be32_to_cpu(block->bb_rightsib) == NULLAGBLOCK) {
-                *stat = 0;
-                return 0;
-        }
-        /*
-         * March up the tree incrementing pointers.
-         * Stop when we don't go off the right edge of a block.
-         */
-        for (lev = level + 1; lev < cur->bc_nlevels; lev++) {
-                bp = cur->bc_bufs[lev];
-                block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-#ifdef DEBUG
-                if ((error = xfs_btree_check_sblock(cur, block, lev, bp)))
-                        return error;
-#endif
-                if (++cur->bc_ptrs[lev] <= be16_to_cpu(block->bb_numrecs))
-                        break;
-                /*
-                 * Read-ahead the right block, we're going to read it
-                 * in the next loop.
-                 */
-                xfs_btree_readahead(cur, lev, XFS_BTCUR_RIGHTRA);
-        }
-        /*
-         * If we went off the root then we are seriously confused.
-         */
-        ASSERT(lev < cur->bc_nlevels);
-        /*
-         * Now walk back down the tree, fixing up the cursor's buffer
-         * pointers and key numbers.
-         */
-        for (bp = cur->bc_bufs[lev], block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-             lev > level; ) {
-                xfs_agblock_t   agbno;  /* block number of btree block */
-
-                agbno = be32_to_cpu(*XFS_ALLOC_PTR_ADDR(block, cur->bc_ptrs[lev], cur));
-                if ((error = xfs_btree_read_bufs(cur->bc_mp, cur->bc_tp,
-                                cur->bc_private.a.agno, agbno, 0, &bp,
-                                XFS_ALLOC_BTREE_REF)))
-                        return error;
-                lev--;
-                xfs_btree_setbuf(cur, lev, bp);
-                block = XFS_BUF_TO_ALLOC_BLOCK(bp);
-                if ((error = xfs_btree_check_sblock(cur, block, lev, bp)))
-                        return error;
-                cur->bc_ptrs[lev] = 1;
-        }
-        *stat = 1;
-        return 0;
-}
-
-/*
  * Insert the current record at the point referenced by cur.
  * The cursor may be inconsistent on return if splits have been done.
  */