[XFS] implement generic xfs_btree_split

Make the btree split code generic. Based on a patch from David Chinner
with lots of changes to follow the original btree implementations more
closely. While this loses some of the generic helper routines for
inserting/moving/removing records it also solves some of the one off bugs
in the original code and makes it easier to verify.

SGI-PV: 985583

SGI-Modid: xfs-linux-melb:xfs-kern:32198a

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, 42 insertions, 158 deletions

diff --git a/fs/xfs/xfs_alloc_btree.c b/fs/xfs/xfs_alloc_btree.c
index 974a412ebc8a..8a8d1aeec52a 100644
--- a/fs/xfs/xfs_alloc_btree.c
+++ b/fs/xfs/xfs_alloc_btree.c
@@ -35,6 +35,7 @@
 #include "xfs_dinode.h"
 #include "xfs_inode.h"
 #include "xfs_btree.h"
+#include "xfs_btree_trace.h"
 #include "xfs_ialloc.h"
 #include "xfs_alloc.h"
 #include "xfs_error.h"
@@ -48,8 +49,6 @@ STATIC void xfs_alloc_log_keys(xfs_btree_cur_t *, xfs_buf_t *, int, int);
 STATIC void xfs_alloc_log_ptrs(xfs_btree_cur_t *, xfs_buf_t *, int, int);
 STATIC void xfs_alloc_log_recs(xfs_btree_cur_t *, xfs_buf_t *, int, int);
 STATIC int xfs_alloc_newroot(xfs_btree_cur_t *, int *);
-STATIC int xfs_alloc_split(xfs_btree_cur_t *, int, xfs_agblock_t *,
-                xfs_alloc_key_t *, xfs_btree_cur_t **, int *);
 
 /*
  * Internal functions.
@@ -695,15 +694,18 @@ xfs_alloc_insrec(
                         if (i)
                                 optr = ptr = cur->bc_ptrs[level];
                         else {
+                                union xfs_btree_ptr bno = { .s = cpu_to_be32(nbno) };
                                 /*
                                  * Next, try splitting the current block in
                                  * half. If this works we have to re-set our
                                  * variables because we could be in a
                                  * different block now.
                                  */
-                                if ((error = xfs_alloc_split(cur, level, &nbno,
-                                                &nkey, &ncur, &i)))
+                                if ((error = xfs_btree_split(cur, level, &bno,
+                                                (union xfs_btree_key *)&nkey,
+                                                &ncur, &i)))
                                         return error;
+                                nbno = be32_to_cpu(bno.s);
                                 if (i) {
                                         bp = cur->bc_bufs[level];
                                         block = XFS_BUF_TO_ALLOC_BLOCK(bp);
@@ -1089,160 +1091,6 @@ xfs_alloc_newroot(
         return 0;
 }
 
-/*
- * Split cur/level block in half.
- * Return new block number and its first record (to be inserted into parent).
- */
-STATIC int                              /* error */
-xfs_alloc_split(
-        xfs_btree_cur_t         *cur,   /* btree cursor */
-        int                     level,  /* level to split */
-        xfs_agblock_t           *bnop,  /* output: block number allocated */
-        xfs_alloc_key_t         *keyp,  /* output: first key of new block */
-        xfs_btree_cur_t         **curp, /* output: new cursor */
-        int                     *stat)  /* success/failure */
-{
-        int                     error;  /* error return value */
-        int                     i;      /* loop index/record number */
-        xfs_agblock_t           lbno;   /* left (current) block number */
-        xfs_buf_t               *lbp;   /* buffer for left block */
-        xfs_alloc_block_t       *left;  /* left (current) btree block */
-        xfs_agblock_t           rbno;   /* right (new) block number */
-        xfs_buf_t               *rbp;   /* buffer for right block */
-        xfs_alloc_block_t       *right; /* right (new) btree block */
-
-        /*
-         * Allocate the new block from the freelist.
-         * If we can't do it, we're toast.  Give up.
-         */
-        error = xfs_alloc_get_freelist(cur->bc_tp,
-                                         cur->bc_private.a.agbp, &rbno, 1);
-        if (error)
-                return error;
-        if (rbno == NULLAGBLOCK) {
-                *stat = 0;
-                return 0;
-        }
-        xfs_trans_agbtree_delta(cur->bc_tp, 1);
-        rbp = xfs_btree_get_bufs(cur->bc_mp, cur->bc_tp, cur->bc_private.a.agno,
-                rbno, 0);
-        /*
-         * Set up the new block as "right".
-         */
-        right = XFS_BUF_TO_ALLOC_BLOCK(rbp);
-        /*
-         * "Left" is the current (according to the cursor) block.
-         */
-        lbp = cur->bc_bufs[level];
-        left = XFS_BUF_TO_ALLOC_BLOCK(lbp);
-#ifdef DEBUG
-        if ((error = xfs_btree_check_sblock(cur, left, level, lbp)))
-                return error;
-#endif
-        /*
-         * Fill in the btree header for the new block.
-         */
-        right->bb_magic = cpu_to_be32(xfs_magics[cur->bc_btnum]);
-        right->bb_level = left->bb_level;
-        right->bb_numrecs = cpu_to_be16(be16_to_cpu(left->bb_numrecs) / 2);
-        /*
-         * Make sure that if there's an odd number of entries now, that
-         * each new block will have the same number of entries.
-         */
-        if ((be16_to_cpu(left->bb_numrecs) & 1) &&
-            cur->bc_ptrs[level] <= be16_to_cpu(right->bb_numrecs) + 1)
-                be16_add_cpu(&right->bb_numrecs, 1);
-        i = be16_to_cpu(left->bb_numrecs) - be16_to_cpu(right->bb_numrecs) + 1;
-        /*
-         * For non-leaf blocks, copy keys and addresses over to the new block.
-         */
-        if (level > 0) {
-                xfs_alloc_key_t *lkp;   /* left btree key pointer */
-                xfs_alloc_ptr_t *lpp;   /* left btree address pointer */
-                xfs_alloc_key_t *rkp;   /* right btree key pointer */
-                xfs_alloc_ptr_t *rpp;   /* right btree address pointer */
-
-                lkp = XFS_ALLOC_KEY_ADDR(left, i, cur);
-                lpp = XFS_ALLOC_PTR_ADDR(left, i, cur);
-                rkp = XFS_ALLOC_KEY_ADDR(right, 1, cur);
-                rpp = XFS_ALLOC_PTR_ADDR(right, 1, cur);
-#ifdef DEBUG
-                for (i = 0; i < be16_to_cpu(right->bb_numrecs); i++) {
-                        if ((error = xfs_btree_check_sptr(cur, be32_to_cpu(lpp[i]), level)))
-                                return error;
-                }
-#endif
-                memcpy(rkp, lkp, be16_to_cpu(right->bb_numrecs) * sizeof(*rkp));
-                memcpy(rpp, lpp, be16_to_cpu(right->bb_numrecs) * sizeof(*rpp));
-                xfs_alloc_log_keys(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-                xfs_alloc_log_ptrs(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-                *keyp = *rkp;
-        }
-        /*
-         * For leaf blocks, copy records over to the new block.
-         */
-        else {
-                xfs_alloc_rec_t *lrp;   /* left btree record pointer */
-                xfs_alloc_rec_t *rrp;   /* right btree record pointer */
-
-                lrp = XFS_ALLOC_REC_ADDR(left, i, cur);
-                rrp = XFS_ALLOC_REC_ADDR(right, 1, cur);
-                memcpy(rrp, lrp, be16_to_cpu(right->bb_numrecs) * sizeof(*rrp));
-                xfs_alloc_log_recs(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-                keyp->ar_startblock = rrp->ar_startblock;
-                keyp->ar_blockcount = rrp->ar_blockcount;
-        }
-        /*
-         * Find the left block number by looking in the buffer.
-         * Adjust numrecs, sibling pointers.
-         */
-        lbno = XFS_DADDR_TO_AGBNO(cur->bc_mp, XFS_BUF_ADDR(lbp));
-        be16_add_cpu(&left->bb_numrecs, -(be16_to_cpu(right->bb_numrecs)));
-        right->bb_rightsib = left->bb_rightsib;
-        left->bb_rightsib = cpu_to_be32(rbno);
-        right->bb_leftsib = cpu_to_be32(lbno);
-        xfs_alloc_log_block(cur->bc_tp, rbp, XFS_BB_ALL_BITS);
-        xfs_alloc_log_block(cur->bc_tp, lbp, XFS_BB_NUMRECS | XFS_BB_RIGHTSIB);
-        /*
-         * If there's a block to the new block's right, make that block
-         * point back to right instead of to left.
-         */
-        if (be32_to_cpu(right->bb_rightsib) != NULLAGBLOCK) {
-                xfs_alloc_block_t       *rrblock;       /* rr btree block */
-                xfs_buf_t               *rrbp;          /* buffer for rrblock */
-
-                if ((error = xfs_btree_read_bufs(cur->bc_mp, cur->bc_tp,
-                                cur->bc_private.a.agno, be32_to_cpu(right->bb_rightsib), 0,
-                                &rrbp, XFS_ALLOC_BTREE_REF)))
-                        return error;
-                rrblock = XFS_BUF_TO_ALLOC_BLOCK(rrbp);
-                if ((error = xfs_btree_check_sblock(cur, rrblock, level, rrbp)))
-                        return error;
-                rrblock->bb_leftsib = cpu_to_be32(rbno);
-                xfs_alloc_log_block(cur->bc_tp, rrbp, XFS_BB_LEFTSIB);
-        }
-        /*
-         * If the cursor is really in the right block, move it there.
-         * If it's just pointing past the last entry in left, then we'll
-         * insert there, so don't change anything in that case.
-         */
-        if (cur->bc_ptrs[level] > be16_to_cpu(left->bb_numrecs) + 1) {
-                xfs_btree_setbuf(cur, level, rbp);
-                cur->bc_ptrs[level] -= be16_to_cpu(left->bb_numrecs);
-        }
-        /*
-         * If there are more levels, we'll need another cursor which refers to
-         * the right block, no matter where this cursor was.
-         */
-        if (level + 1 < cur->bc_nlevels) {
-                if ((error = xfs_btree_dup_cursor(cur, curp)))
-                        return error;
-                (*curp)->bc_ptrs[level + 1]++;
-        }
-        *bnop = rbno;
-        *stat = 1;
-        return 0;
-}
 
 /*
  * Externally visible routines.
@@ -1396,6 +1244,41 @@ xfs_allocbt_dup_cursor(
                         cur->bc_btnum);
 }
 
+STATIC int
+xfs_allocbt_alloc_block(
+        struct xfs_btree_cur    *cur,
+        union xfs_btree_ptr     *start,
+        union xfs_btree_ptr     *new,
+        int                     length,
+        int                     *stat)
+{
+        int                     error;
+        xfs_agblock_t           bno;
+
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+
+        /* Allocate the new block from the freelist. If we can't, give up.  */
+        error = xfs_alloc_get_freelist(cur->bc_tp, cur->bc_private.a.agbp,
+                                       &bno, 1);
+        if (error) {
+                XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
+                return error;
+        }
+
+        if (bno == NULLAGBLOCK) {
+                XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+                *stat = 0;
+                return 0;
+        }
+
+        xfs_trans_agbtree_delta(cur->bc_tp, 1);
+        new->s = cpu_to_be32(bno);
+
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+        *stat = 1;
+        return 0;
+}
+
 /*
  * Update the longest extent in the AGF
  */
@@ -1557,6 +1440,7 @@ static const struct xfs_btree_ops xfs_allocbt_ops = {
         .key_len                = sizeof(xfs_alloc_key_t),
 
         .dup_cursor             = xfs_allocbt_dup_cursor,
+        .alloc_block            = xfs_allocbt_alloc_block,
         .update_lastrec         = xfs_allocbt_update_lastrec,
         .get_maxrecs            = xfs_allocbt_get_maxrecs,
         .init_key_from_rec      = xfs_allocbt_init_key_from_rec,