From 8df4da4a0a642d3a016028c0d922bcb4d5a4a6d7 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 30 Oct 2008 16:55:58 +1100 Subject: [XFS] implement generic xfs_btree_decrement From: Dave Chinner [hch: split out from bigger patch and minor adaptions] SGI-PV: 985583 SGI-Modid: xfs-linux-melb:xfs-kern:32191a 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 | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 99 insertions(+) (limited to 'fs/xfs/xfs_btree.c') diff --git a/fs/xfs/xfs_btree.c b/fs/xfs/xfs_btree.c index e9ab86b..3d561f8 100644 --- a/fs/xfs/xfs_btree.c +++ b/fs/xfs/xfs_btree.c @@ -1171,3 +1171,102 @@ error0: XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR); return error; } + +/* + * Decrement cursor by one record at the level. + * For nonzero levels the leaf-ward information is untouched. + */ +int /* error */ +xfs_btree_decrement( + struct xfs_btree_cur *cur, + int level, + int *stat) /* success/failure */ +{ + struct xfs_btree_block *block; + xfs_buf_t *bp; + int error; /* error return value */ + int lev; + union xfs_btree_ptr ptr; + + XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY); + XFS_BTREE_TRACE_ARGI(cur, level); + + ASSERT(level < cur->bc_nlevels); + + /* Read-ahead to the left at this level. */ + xfs_btree_readahead(cur, level, XFS_BTCUR_LEFTRA); + + /* We're done if we remain in the block after the decrement. */ + if (--cur->bc_ptrs[level] > 0) + goto out1; + + /* Get a pointer to the btree block. */ + block = xfs_btree_get_block(cur, level, &bp); + +#ifdef DEBUG + error = xfs_btree_check_block(cur, block, level, bp); + if (error) + goto error0; +#endif + + /* Fail if we just went off the left edge of the tree. */ + xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_LEFTSIB); + if (xfs_btree_ptr_is_null(cur, &ptr)) + goto out0; + + XFS_BTREE_STATS_INC(cur, decrement); + + /* + * March up the tree decrementing pointers. + * Stop when we don't go off the left edge of a block. + */ + for (lev = level + 1; lev < cur->bc_nlevels; lev++) { + if (--cur->bc_ptrs[lev] > 0) + break; + /* Read-ahead the left block for the next loop. */ + xfs_btree_readahead(cur, lev, XFS_BTCUR_LEFTRA); + } + + /* + * If we went off the root then we are seriously confused. + * or the root of the tree is in an inode. + */ + if (lev == cur->bc_nlevels) { + if (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) + goto out0; + ASSERT(0); + error = EFSCORRUPTED; + goto error0; + } + ASSERT(lev < cur->bc_nlevels); + + /* + * Now walk back down the tree, fixing up the cursor's buffer + * pointers and key numbers. + */ + for (block = xfs_btree_get_block(cur, lev, &bp); lev > level; ) { + union xfs_btree_ptr *ptrp; + + ptrp = xfs_btree_ptr_addr(cur, cur->bc_ptrs[lev], block); + error = xfs_btree_read_buf_block(cur, ptrp, --lev, + 0, &block, &bp); + if (error) + goto error0; + xfs_btree_setbuf(cur, lev, bp); + cur->bc_ptrs[lev] = xfs_btree_get_numrecs(block); + } +out1: + 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 v1.1