[XFS] implement generic xfs_btree_rshift

Make the btree right shift 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:32196a

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, 318 insertions, 1 deletions

diff --git a/fs/xfs/xfs_btree.c b/fs/xfs/xfs_btree.c
index 205272f282d9..e1a213781849 100644
--- a/fs/xfs/xfs_btree.c
+++ b/fs/xfs/xfs_btree.c
@@ -1118,6 +1118,77 @@ xfs_btree_copy_recs(
 }
 
 /*
+ * Copy block pointers from one btree block to another.
+ */
+STATIC void
+xfs_btree_copy_ptrs(
+        struct xfs_btree_cur    *cur,
+        union xfs_btree_ptr     *dst_ptr,
+        union xfs_btree_ptr     *src_ptr,
+        int                     numptrs)
+{
+        ASSERT(numptrs >= 0);
+        memcpy(dst_ptr, src_ptr, numptrs * xfs_btree_ptr_len(cur));
+}
+
+/*
+ * Shift keys one index left/right inside a single btree block.
+ */
+STATIC void
+xfs_btree_shift_keys(
+        struct xfs_btree_cur    *cur,
+        union xfs_btree_key     *key,
+        int                     dir,
+        int                     numkeys)
+{
+        char                    *dst_key;
+
+        ASSERT(numkeys >= 0);
+        ASSERT(dir == 1 || dir == -1);
+
+        dst_key = (char *)key + (dir * cur->bc_ops->key_len);
+        memmove(dst_key, key, numkeys * cur->bc_ops->key_len);
+}
+
+/*
+ * Shift records one index left/right inside a single btree block.
+ */
+STATIC void
+xfs_btree_shift_recs(
+        struct xfs_btree_cur    *cur,
+        union xfs_btree_rec     *rec,
+        int                     dir,
+        int                     numrecs)
+{
+        char                    *dst_rec;
+
+        ASSERT(numrecs >= 0);
+        ASSERT(dir == 1 || dir == -1);
+
+        dst_rec = (char *)rec + (dir * cur->bc_ops->rec_len);
+        memmove(dst_rec, rec, numrecs * cur->bc_ops->rec_len);
+}
+
+/*
+ * Shift block pointers one index left/right inside a single btree block.
+ */
+STATIC void
+xfs_btree_shift_ptrs(
+        struct xfs_btree_cur    *cur,
+        union xfs_btree_ptr     *ptr,
+        int                     dir,
+        int                     numptrs)
+{
+        char                    *dst_ptr;
+
+        ASSERT(numptrs >= 0);
+        ASSERT(dir == 1 || dir == -1);
+
+        dst_ptr = (char *)ptr + (dir * xfs_btree_ptr_len(cur));
+        memmove(dst_ptr, ptr, numptrs * xfs_btree_ptr_len(cur));
+}
+
+/*
  * Log key values from the btree block.
  */
 STATIC void
@@ -1163,6 +1234,79 @@ xfs_btree_log_recs(
 }
 
 /*
+ * Log block pointer fields from a btree block (nonleaf).
+ */
+STATIC void
+xfs_btree_log_ptrs(
+        struct xfs_btree_cur    *cur,   /* btree cursor */
+        struct xfs_buf          *bp,    /* buffer containing btree block */
+        int                     first,  /* index of first pointer to log */
+        int                     last)   /* index of last pointer to log */
+{
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+        XFS_BTREE_TRACE_ARGBII(cur, bp, first, last);
+
+        if (bp) {
+                struct xfs_btree_block  *block = XFS_BUF_TO_BLOCK(bp);
+                int                     level = xfs_btree_get_level(block);
+
+                xfs_trans_log_buf(cur->bc_tp, bp,
+                                xfs_btree_ptr_offset(cur, first, level),
+                                xfs_btree_ptr_offset(cur, last + 1, level) - 1);
+        } else {
+                xfs_trans_log_inode(cur->bc_tp, cur->bc_private.b.ip,
+                        xfs_ilog_fbroot(cur->bc_private.b.whichfork));
+        }
+
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+}
+
+/*
+ * Log fields from a btree block header.
+ */
+STATIC void
+xfs_btree_log_block(
+        struct xfs_btree_cur    *cur,   /* btree cursor */
+        struct xfs_buf          *bp,    /* buffer containing btree block */
+        int                     fields) /* mask of fields: XFS_BB_... */
+{
+        int                     first;  /* first byte offset logged */
+        int                     last;   /* last byte offset logged */
+        static const short      soffsets[] = {  /* table of offsets (short) */
+                offsetof(struct xfs_btree_sblock, bb_magic),
+                offsetof(struct xfs_btree_sblock, bb_level),
+                offsetof(struct xfs_btree_sblock, bb_numrecs),
+                offsetof(struct xfs_btree_sblock, bb_leftsib),
+                offsetof(struct xfs_btree_sblock, bb_rightsib),
+                sizeof(struct xfs_btree_sblock)
+        };
+        static const short      loffsets[] = {  /* table of offsets (long) */
+                offsetof(struct xfs_btree_lblock, bb_magic),
+                offsetof(struct xfs_btree_lblock, bb_level),
+                offsetof(struct xfs_btree_lblock, bb_numrecs),
+                offsetof(struct xfs_btree_lblock, bb_leftsib),
+                offsetof(struct xfs_btree_lblock, bb_rightsib),
+                sizeof(struct xfs_btree_lblock)
+        };
+
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+        XFS_BTREE_TRACE_ARGBI(cur, bp, fields);
+
+        if (bp) {
+                xfs_btree_offsets(fields,
+                                  (cur->bc_flags & XFS_BTREE_LONG_PTRS) ?
+                                        loffsets : soffsets,
+                                  XFS_BB_NUM_BITS, &first, &last);
+                xfs_trans_log_buf(cur->bc_tp, bp, first, last);
+        } else {
+                xfs_trans_log_inode(cur->bc_tp, cur->bc_private.b.ip,
+                        xfs_ilog_fbroot(cur->bc_private.b.whichfork));
+        }
+
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+}
+
+/*
  * Increment cursor by one record at the level.
  * For nonzero levels the leaf-ward information is untouched.
  */
@@ -1368,7 +1512,6 @@ error0:
         return error;
 }
 
-
 STATIC int
 xfs_btree_lookup_get_block(
         struct xfs_btree_cur    *cur,   /* btree cursor */
@@ -1697,3 +1840,177 @@ error0:
         return error;
 }
 
+/*
+ * Move 1 record right from cur/level if possible.
+ * Update cur to reflect the new path.
+ */
+int                                     /* error */
+xfs_btree_rshift(
+        struct xfs_btree_cur    *cur,
+        int                     level,
+        int                     *stat)          /* success/failure */
+{
+        union xfs_btree_key     key;            /* btree key */
+        struct xfs_buf          *lbp;           /* left buffer pointer */
+        struct xfs_btree_block  *left;          /* left btree block */
+        struct xfs_buf          *rbp;           /* right buffer pointer */
+        struct xfs_btree_block  *right;         /* right btree block */
+        struct xfs_btree_cur    *tcur;          /* temporary btree cursor */
+        union xfs_btree_ptr     rptr;           /* right block pointer */
+        union xfs_btree_key     *rkp;           /* right btree key */
+        int                     rrecs;          /* right record count */
+        int                     lrecs;          /* left record count */
+        int                     error;          /* error return value */
+        int                     i;              /* loop counter */
+
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+        XFS_BTREE_TRACE_ARGI(cur, level);
+
+        if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
+            (level == cur->bc_nlevels - 1))
+                goto out0;
+
+        /* Set up variables for this block as "left". */
+        left = xfs_btree_get_block(cur, level, &lbp);
+
+#ifdef DEBUG
+        error = xfs_btree_check_block(cur, left, level, lbp);
+        if (error)
+                goto error0;
+#endif
+
+        /* If we've got no right sibling then we can't shift an entry right. */
+        xfs_btree_get_sibling(cur, left, &rptr, XFS_BB_RIGHTSIB);
+        if (xfs_btree_ptr_is_null(cur, &rptr))
+                goto out0;
+
+        /*
+         * If the cursor entry is the one that would be moved, don't
+         * do it... it's too complicated.
+         */
+        lrecs = xfs_btree_get_numrecs(left);
+        if (cur->bc_ptrs[level] >= lrecs)
+                goto out0;
+
+        /* Set up the right neighbor as "right". */
+        error = xfs_btree_read_buf_block(cur, &rptr, level, 0, &right, &rbp);
+        if (error)
+                goto error0;
+
+        /* If it's full, it can't take another entry. */
+        rrecs = xfs_btree_get_numrecs(right);
+        if (rrecs == cur->bc_ops->get_maxrecs(cur, level))
+                goto out0;
+
+        XFS_BTREE_STATS_INC(cur, rshift);
+        XFS_BTREE_STATS_ADD(cur, moves, rrecs);
+
+        /*
+         * Make a hole at the start of the right neighbor block, then
+         * copy the last left block entry to the hole.
+         */
+        if (level > 0) {
+                /* It's a nonleaf. make a hole in the keys and ptrs */
+                union xfs_btree_key     *lkp;
+                union xfs_btree_ptr     *lpp;
+                union xfs_btree_ptr     *rpp;
+
+                lkp = xfs_btree_key_addr(cur, lrecs, left);
+                lpp = xfs_btree_ptr_addr(cur, lrecs, left);
+                rkp = xfs_btree_key_addr(cur, 1, right);
+                rpp = xfs_btree_ptr_addr(cur, 1, right);
+
+#ifdef DEBUG
+                for (i = rrecs - 1; i >= 0; i--) {
+                        error = xfs_btree_check_ptr(cur, rpp, i, level);
+                        if (error)
+                                goto error0;
+                }
+#endif
+
+                xfs_btree_shift_keys(cur, rkp, 1, rrecs);
+                xfs_btree_shift_ptrs(cur, rpp, 1, rrecs);
+
+#ifdef DEBUG
+                error = xfs_btree_check_ptr(cur, lpp, 0, level);
+                if (error)
+                        goto error0;
+#endif
+
+                /* Now put the new data in, and log it. */
+                xfs_btree_copy_keys(cur, rkp, lkp, 1);
+                xfs_btree_copy_ptrs(cur, rpp, lpp, 1);
+
+                xfs_btree_log_keys(cur, rbp, 1, rrecs + 1);
+                xfs_btree_log_ptrs(cur, rbp, 1, rrecs + 1);
+
+                xfs_btree_check_key(cur->bc_btnum, rkp,
+                                    xfs_btree_key_addr(cur, 2, right));
+        } else {
+                /* It's a leaf. make a hole in the records */
+                union xfs_btree_rec     *lrp;
+                union xfs_btree_rec     *rrp;
+
+                lrp = xfs_btree_rec_addr(cur, lrecs, left);
+                rrp = xfs_btree_rec_addr(cur, 1, right);
+
+                xfs_btree_shift_recs(cur, rrp, 1, rrecs);
+
+                /* Now put the new data in, and log it. */
+                xfs_btree_copy_recs(cur, rrp, lrp, 1);
+                xfs_btree_log_recs(cur, rbp, 1, rrecs + 1);
+
+                cur->bc_ops->init_key_from_rec(&key, rrp);
+                rkp = &key;
+
+                xfs_btree_check_rec(cur->bc_btnum, rrp,
+                                    xfs_btree_rec_addr(cur, 2, right));
+        }
+
+        /*
+         * Decrement and log left's numrecs, bump and log right's numrecs.
+         */
+        xfs_btree_set_numrecs(left, --lrecs);
+        xfs_btree_log_block(cur, lbp, XFS_BB_NUMRECS);
+
+        xfs_btree_set_numrecs(right, ++rrecs);
+        xfs_btree_log_block(cur, rbp, XFS_BB_NUMRECS);
+
+        /*
+         * Using a temporary cursor, update the parent key values of the
+         * block on the right.
+         */
+        error = xfs_btree_dup_cursor(cur, &tcur);
+        if (error)
+                goto error0;
+        i = xfs_btree_lastrec(tcur, level);
+        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
+
+        error = xfs_btree_increment(tcur, level, &i);
+        if (error)
+                goto error1;
+
+        error = xfs_btree_updkey(tcur, rkp, level + 1);
+        if (error)
+                goto error1;
+
+        xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
+
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+        *stat = 1;
+        return 0;
+
+out0:
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+        *stat = 0;
+        return 0;
+
+error0:
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
+        return error;
+
+error1:
+        XFS_BTREE_TRACE_CURSOR(tcur, XBT_ERROR);
+        xfs_btree_del_cursor(tcur, XFS_BTREE_ERROR);
+        return error;
+}