From f5eb8e7ca58bc1e92436614444006120d21668ba Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 30 Oct 2008 16:57:03 +1100 Subject: [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 Signed-off-by: Lachlan McIlroy Signed-off-by: Bill O'Donnell Signed-off-by: David Chinner --- fs/xfs/xfs_btree.c | 268 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 268 insertions(+) (limited to 'fs/xfs/xfs_btree.c') diff --git a/fs/xfs/xfs_btree.c b/fs/xfs/xfs_btree.c index 2b0d1422c4c..80576695fbe 100644 --- a/fs/xfs/xfs_btree.c +++ b/fs/xfs/xfs_btree.c @@ -988,6 +988,48 @@ xfs_btree_get_sibling( } } +STATIC void +xfs_btree_set_sibling( + struct xfs_btree_cur *cur, + struct xfs_btree_block *block, + union xfs_btree_ptr *ptr, + int lr) +{ + ASSERT(lr == XFS_BB_LEFTSIB || lr == XFS_BB_RIGHTSIB); + + if (cur->bc_flags & XFS_BTREE_LONG_PTRS) { + if (lr == XFS_BB_RIGHTSIB) + block->bb_u.l.bb_rightsib = ptr->l; + else + block->bb_u.l.bb_leftsib = ptr->l; + } else { + if (lr == XFS_BB_RIGHTSIB) + block->bb_u.s.bb_rightsib = ptr->s; + else + block->bb_u.s.bb_leftsib = ptr->s; + } +} + +STATIC void +xfs_btree_init_block( + struct xfs_btree_cur *cur, + int level, + int numrecs, + struct xfs_btree_block *new) /* new block */ +{ + new->bb_magic = cpu_to_be32(xfs_magics[cur->bc_btnum]); + new->bb_level = cpu_to_be16(level); + new->bb_numrecs = cpu_to_be16(numrecs); + + if (cur->bc_flags & XFS_BTREE_LONG_PTRS) { + new->bb_u.l.bb_leftsib = cpu_to_be64(NULLFSBLOCK); + new->bb_u.l.bb_rightsib = cpu_to_be64(NULLFSBLOCK); + } else { + new->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK); + new->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK); + } +} + /* * Return true if ptr is the last record in the btree and * we need to track updateѕ to this record. The decision @@ -1012,6 +1054,21 @@ xfs_btree_is_lastrec( return 1; } +STATIC void +xfs_btree_buf_to_ptr( + struct xfs_btree_cur *cur, + struct xfs_buf *bp, + union xfs_btree_ptr *ptr) +{ + if (cur->bc_flags & XFS_BTREE_LONG_PTRS) + ptr->l = cpu_to_be64(XFS_DADDR_TO_FSB(cur->bc_mp, + XFS_BUF_ADDR(bp))); + else { + ptr->s = cpu_to_be32(XFS_DADDR_TO_AGBNO(cur->bc_mp, + XFS_BUF_ADDR(bp))); + } +} + STATIC xfs_daddr_t xfs_btree_ptr_to_daddr( struct xfs_btree_cur *cur, @@ -1051,6 +1108,31 @@ xfs_btree_set_refs( } } +STATIC int +xfs_btree_get_buf_block( + struct xfs_btree_cur *cur, + union xfs_btree_ptr *ptr, + int flags, + struct xfs_btree_block **block, + struct xfs_buf **bpp) +{ + struct xfs_mount *mp = cur->bc_mp; + xfs_daddr_t d; + + /* need to sort out how callers deal with failures first */ + ASSERT(!(flags & XFS_BUF_TRYLOCK)); + + d = xfs_btree_ptr_to_daddr(cur, ptr); + *bpp = xfs_trans_get_buf(cur->bc_tp, mp->m_ddev_targp, d, + mp->m_bsize, flags); + + ASSERT(*bpp); + ASSERT(!XFS_BUF_GETERROR(*bpp)); + + *block = XFS_BUF_TO_BLOCK(*bpp); + return 0; +} + /* * Read in the buffer at the given ptr and return the buffer and * the block pointer within the buffer. @@ -2199,3 +2281,189 @@ error1: xfs_btree_del_cursor(tcur, XFS_BTREE_ERROR); return error; } + +/* + * Split cur/level block in half. + * Return new block number and the key to its first + * record (to be inserted into parent). + */ +int /* error */ +xfs_btree_split( + struct xfs_btree_cur *cur, + int level, + union xfs_btree_ptr *ptrp, + union xfs_btree_key *key, + struct xfs_btree_cur **curp, + int *stat) /* success/failure */ +{ + union xfs_btree_ptr lptr; /* left sibling block ptr */ + struct xfs_buf *lbp; /* left buffer pointer */ + struct xfs_btree_block *left; /* left btree block */ + union xfs_btree_ptr rptr; /* right sibling block ptr */ + struct xfs_buf *rbp; /* right buffer pointer */ + struct xfs_btree_block *right; /* right btree block */ + union xfs_btree_ptr rrptr; /* right-right sibling ptr */ + struct xfs_buf *rrbp; /* right-right buffer pointer */ + struct xfs_btree_block *rrblock; /* right-right btree block */ + int lrecs; + int rrecs; + int src_index; + int error; /* error return value */ +#ifdef DEBUG + int i; +#endif + + XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY); + XFS_BTREE_TRACE_ARGIPK(cur, level, *ptrp, key); + + XFS_BTREE_STATS_INC(cur, split); + + /* Set up left block (current one). */ + left = xfs_btree_get_block(cur, level, &lbp); + +#ifdef DEBUG + error = xfs_btree_check_block(cur, left, level, lbp); + if (error) + goto error0; +#endif + + xfs_btree_buf_to_ptr(cur, lbp, &lptr); + + /* Allocate the new block. If we can't do it, we're toast. Give up. */ + error = cur->bc_ops->alloc_block(cur, &lptr, &rptr, 1, stat); + if (error) + goto error0; + if (*stat == 0) + goto out0; + XFS_BTREE_STATS_INC(cur, alloc); + + /* Set up the new block as "right". */ + error = xfs_btree_get_buf_block(cur, &rptr, 0, &right, &rbp); + if (error) + goto error0; + + /* Fill in the btree header for the new right block. */ + xfs_btree_init_block(cur, xfs_btree_get_level(left), 0, right); + + /* + * Split the entries between the old and the new block evenly. + * Make sure that if there's an odd number of entries now, that + * each new block will have the same number of entries. + */ + lrecs = xfs_btree_get_numrecs(left); + rrecs = lrecs / 2; + if ((lrecs & 1) && cur->bc_ptrs[level] <= rrecs + 1) + rrecs++; + src_index = (lrecs - rrecs + 1); + + XFS_BTREE_STATS_ADD(cur, moves, rrecs); + + /* + * Copy btree block entries from the left block over to the + * new block, the right. Update the right block and log the + * changes. + */ + if (level > 0) { + /* It's a non-leaf. Move keys and pointers. */ + union xfs_btree_key *lkp; /* left btree key */ + union xfs_btree_ptr *lpp; /* left address pointer */ + union xfs_btree_key *rkp; /* right btree key */ + union xfs_btree_ptr *rpp; /* right address pointer */ + + lkp = xfs_btree_key_addr(cur, src_index, left); + lpp = xfs_btree_ptr_addr(cur, src_index, left); + rkp = xfs_btree_key_addr(cur, 1, right); + rpp = xfs_btree_ptr_addr(cur, 1, right); + +#ifdef DEBUG + for (i = src_index; i < rrecs; i++) { + error = xfs_btree_check_ptr(cur, lpp, i, level); + if (error) + goto error0; + } +#endif + + xfs_btree_copy_keys(cur, rkp, lkp, rrecs); + xfs_btree_copy_ptrs(cur, rpp, lpp, rrecs); + + xfs_btree_log_keys(cur, rbp, 1, rrecs); + xfs_btree_log_ptrs(cur, rbp, 1, rrecs); + + /* Grab the keys to the entries moved to the right block */ + xfs_btree_copy_keys(cur, key, rkp, 1); + } else { + /* It's a leaf. Move records. */ + union xfs_btree_rec *lrp; /* left record pointer */ + union xfs_btree_rec *rrp; /* right record pointer */ + + lrp = xfs_btree_rec_addr(cur, src_index, left); + rrp = xfs_btree_rec_addr(cur, 1, right); + + xfs_btree_copy_recs(cur, rrp, lrp, rrecs); + xfs_btree_log_recs(cur, rbp, 1, rrecs); + + cur->bc_ops->init_key_from_rec(key, + xfs_btree_rec_addr(cur, 1, right)); + } + + + /* + * Find the left block number by looking in the buffer. + * Adjust numrecs, sibling pointers. + */ + xfs_btree_get_sibling(cur, left, &rrptr, XFS_BB_RIGHTSIB); + xfs_btree_set_sibling(cur, right, &rrptr, XFS_BB_RIGHTSIB); + xfs_btree_set_sibling(cur, right, &lptr, XFS_BB_LEFTSIB); + xfs_btree_set_sibling(cur, left, &rptr, XFS_BB_RIGHTSIB); + + lrecs -= rrecs; + xfs_btree_set_numrecs(left, lrecs); + xfs_btree_set_numrecs(right, xfs_btree_get_numrecs(right) + rrecs); + + xfs_btree_log_block(cur, rbp, XFS_BB_ALL_BITS); + xfs_btree_log_block(cur, 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 (!xfs_btree_ptr_is_null(cur, &rrptr)) { + error = xfs_btree_read_buf_block(cur, &rrptr, level, + 0, &rrblock, &rrbp); + if (error) + goto error0; + xfs_btree_set_sibling(cur, rrblock, &rptr, XFS_BB_LEFTSIB); + xfs_btree_log_block(cur, 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] > lrecs + 1) { + xfs_btree_setbuf(cur, level, rbp); + cur->bc_ptrs[level] -= lrecs; + } + /* + * If there are more levels, we'll need another cursor which refers + * the right block, no matter where this cursor was. + */ + if (level + 1 < cur->bc_nlevels) { + error = xfs_btree_dup_cursor(cur, curp); + if (error) + goto error0; + (*curp)->bc_ptrs[level + 1]++; + } + *ptrp = rptr; + 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; +} -- cgit v1.2.3