cur->bc_flags &= ~XFS_BTREE_STAGING;
cur->bc_tp = tp;
}
+
+/*
+ * Bulk Loading of Staged Btrees
+ * =============================
+ *
+ * This interface is used with a staged btree cursor to create a totally new
+ * btree with a large number of records (i.e. more than what would fit in a
+ * single root block). When the creation is complete, the new root can be
+ * linked atomically into the filesystem by committing the staged cursor.
+ *
+ * Creation of a new btree proceeds roughly as follows:
+ *
+ * The first step is to initialize an appropriate fake btree root structure and
+ * then construct a staged btree cursor. Refer to the block comments about
+ * "Bulk Loading for AG Btrees" and "Bulk Loading for Inode-Rooted Btrees" for
+ * more information about how to do this.
+ *
+ * The second step is to initialize a struct xfs_btree_bload context as
+ * documented in the structure definition.
+ *
+ * The third step is to call xfs_btree_bload_compute_geometry to compute the
+ * height of and the number of blocks needed to construct the btree. See the
+ * section "Computing the Geometry of the New Btree" for details about this
+ * computation.
+ *
+ * In step four, the caller must allocate xfs_btree_bload.nr_blocks blocks and
+ * save them for later use by ->claim_block(). Bulk loading requires all
+ * blocks to be allocated beforehand to avoid ENOSPC failures midway through a
+ * rebuild, and to minimize seek distances of the new btree.
+ *
+ * Step five is to call xfs_btree_bload() to start constructing the btree.
+ *
+ * The final step is to commit the staging btree cursor, which logs the new
+ * btree root and turns the staging cursor into a regular cursor. The caller
+ * is responsible for cleaning up the previous btree blocks, if any.
+ *
+ * Computing the Geometry of the New Btree
+ * =======================================
+ *
+ * The number of items placed in each btree block is computed via the following
+ * algorithm: For leaf levels, the number of items for the level is nr_records
+ * in the bload structure. For node levels, the number of items for the level
+ * is the number of blocks in the next lower level of the tree. For each
+ * level, the desired number of items per block is defined as:
+ *
+ * desired = max(minrecs, maxrecs - slack factor)
+ *
+ * The number of blocks for the level is defined to be:
+ *
+ * blocks = floor(nr_items / desired)
+ *
+ * Note this is rounded down so that the npb calculation below will never fall
+ * below minrecs. The number of items that will actually be loaded into each
+ * btree block is defined as:
+ *
+ * npb = nr_items / blocks
+ *
+ * Some of the leftmost blocks in the level will contain one extra record as
+ * needed to handle uneven division. If the number of records in any block
+ * would exceed maxrecs for that level, blocks is incremented and npb is
+ * recalculated.
+ *
+ * In other words, we compute the number of blocks needed to satisfy a given
+ * loading level, then spread the items as evenly as possible.
+ *
+ * The height and number of fs blocks required to create the btree are computed
+ * and returned via btree_height and nr_blocks.
+ */
+
+/*
+ * Put a btree block that we're loading onto the ordered list and release it.
+ * The btree blocks will be written to disk when bulk loading is finished.
+ */
+static void
+xfs_btree_bload_drop_buf(
+ struct list_head *buffers_list,
+ struct xfs_buf **bpp)
+{
+ if (*bpp == NULL)
+ return;
+
+ if (!xfs_buf_delwri_queue(*bpp, buffers_list))
+ ASSERT(0);
+
+ xfs_buf_relse(*bpp);
+ *bpp = NULL;
+}
+
+/*
+ * Allocate and initialize one btree block for bulk loading.
+ *
+ * The new btree block will have its level and numrecs fields set to the values
+ * of the level and nr_this_block parameters, respectively.
+ *
+ * The caller should ensure that ptrp, bpp, and blockp refer to the left
+ * sibling of the new block, if there is any. On exit, ptrp, bpp, and blockp
+ * will all point to the new block.
+ */
+STATIC int
+xfs_btree_bload_prep_block(
+ struct xfs_btree_cur *cur,
+ struct xfs_btree_bload *bbl,
+ struct list_head *buffers_list,
+ unsigned int level,
+ unsigned int nr_this_block,
+ union xfs_btree_ptr *ptrp, /* in/out */
+ struct xfs_buf **bpp, /* in/out */
+ struct xfs_btree_block **blockp, /* in/out */
+ void *priv)
+{
+ union xfs_btree_ptr new_ptr;
+ struct xfs_buf *new_bp;
+ struct xfs_btree_block *new_block;
+ int ret;
+
+ if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
+ level == cur->bc_nlevels - 1) {
+ struct xfs_ifork *ifp = xfs_btree_ifork_ptr(cur);
+ size_t new_size;
+
+ ASSERT(*bpp == NULL);
+
+ /* Allocate a new incore btree root block. */
+ new_size = bbl->iroot_size(cur, nr_this_block, priv);
+ ifp->if_broot = kmem_zalloc(new_size, 0);
+ ifp->if_broot_bytes = (int)new_size;
+ ifp->if_flags |= XFS_IFBROOT;
+
+ /* Initialize it and send it out. */
+ xfs_btree_init_block_int(cur->bc_mp, ifp->if_broot,
+ XFS_BUF_DADDR_NULL, cur->bc_btnum, level,
+ nr_this_block, cur->bc_ino.ip->i_ino,
+ cur->bc_flags);
+
+ *bpp = NULL;
+ *blockp = ifp->if_broot;
+ xfs_btree_set_ptr_null(cur, ptrp);
+ return 0;
+ }
+
+ /* Claim one of the caller's preallocated blocks. */
+ xfs_btree_set_ptr_null(cur, &new_ptr);
+ ret = bbl->claim_block(cur, &new_ptr, priv);
+ if (ret)
+ return ret;
+
+ ASSERT(!xfs_btree_ptr_is_null(cur, &new_ptr));
+
+ ret = xfs_btree_get_buf_block(cur, &new_ptr, &new_block, &new_bp);
+ if (ret)
+ return ret;
+
+ /*
+ * The previous block (if any) is the left sibling of the new block,
+ * so set its right sibling pointer to the new block and drop it.
+ */
+ if (*blockp)
+ xfs_btree_set_sibling(cur, *blockp, &new_ptr, XFS_BB_RIGHTSIB);
+ xfs_btree_bload_drop_buf(buffers_list, bpp);
+
+ /* Initialize the new btree block. */
+ xfs_btree_init_block_cur(cur, new_bp, level, nr_this_block);
+ xfs_btree_set_sibling(cur, new_block, ptrp, XFS_BB_LEFTSIB);
+
+ /* Set the out parameters. */
+ *bpp = new_bp;
+ *blockp = new_block;
+ xfs_btree_copy_ptrs(cur, ptrp, &new_ptr, 1);
+ return 0;
+}
+
+/* Load one leaf block. */
+STATIC int
+xfs_btree_bload_leaf(
+ struct xfs_btree_cur *cur,
+ unsigned int recs_this_block,
+ xfs_btree_bload_get_record_fn get_record,
+ struct xfs_btree_block *block,
+ void *priv)
+{
+ unsigned int j;
+ int ret;
+
+ /* Fill the leaf block with records. */
+ for (j = 1; j <= recs_this_block; j++) {
+ union xfs_btree_rec *block_rec;
+
+ ret = get_record(cur, priv);
+ if (ret)
+ return ret;
+ block_rec = xfs_btree_rec_addr(cur, j, block);
+ cur->bc_ops->init_rec_from_cur(cur, block_rec);
+ }
+
+ return 0;
+}
+
+/*
+ * Load one node block with key/ptr pairs.
+ *
+ * child_ptr must point to a block within the next level down in the tree. A
+ * key/ptr entry will be created in the new node block to the block pointed to
+ * by child_ptr. On exit, child_ptr points to the next block on the child
+ * level that needs processing.
+ */
+STATIC int
+xfs_btree_bload_node(
+ struct xfs_btree_cur *cur,
+ unsigned int recs_this_block,
+ union xfs_btree_ptr *child_ptr,
+ struct xfs_btree_block *block)
+{
+ unsigned int j;
+ int ret;
+
+ /* Fill the node block with keys and pointers. */
+ for (j = 1; j <= recs_this_block; j++) {
+ union xfs_btree_key child_key;
+ union xfs_btree_ptr *block_ptr;
+ union xfs_btree_key *block_key;
+ struct xfs_btree_block *child_block;
+ struct xfs_buf *child_bp;
+
+ ASSERT(!xfs_btree_ptr_is_null(cur, child_ptr));
+
+ ret = xfs_btree_get_buf_block(cur, child_ptr, &child_block,
+ &child_bp);
+ if (ret)
+ return ret;
+
+ block_ptr = xfs_btree_ptr_addr(cur, j, block);
+ xfs_btree_copy_ptrs(cur, block_ptr, child_ptr, 1);
+
+ block_key = xfs_btree_key_addr(cur, j, block);
+ xfs_btree_get_keys(cur, child_block, &child_key);
+ xfs_btree_copy_keys(cur, block_key, &child_key, 1);
+
+ xfs_btree_get_sibling(cur, child_block, child_ptr,
+ XFS_BB_RIGHTSIB);
+ xfs_buf_relse(child_bp);
+ }
+
+ return 0;
+}
+
+/*
+ * Compute the maximum number of records (or keyptrs) per block that we want to
+ * install at this level in the btree. Caller is responsible for having set
+ * @cur->bc_ino.forksize to the desired fork size, if appropriate.
+ */
+STATIC unsigned int
+xfs_btree_bload_max_npb(
+ struct xfs_btree_cur *cur,
+ struct xfs_btree_bload *bbl,
+ unsigned int level)
+{
+ unsigned int ret;
+
+ if (level == cur->bc_nlevels - 1 && cur->bc_ops->get_dmaxrecs)
+ return cur->bc_ops->get_dmaxrecs(cur, level);
+
+ ret = cur->bc_ops->get_maxrecs(cur, level);
+ if (level == 0)
+ ret -= bbl->leaf_slack;
+ else
+ ret -= bbl->node_slack;
+ return ret;
+}
+
+/*
+ * Compute the desired number of records (or keyptrs) per block that we want to
+ * install at this level in the btree, which must be somewhere between minrecs
+ * and max_npb. The caller is free to install fewer records per block.
+ */
+STATIC unsigned int
+xfs_btree_bload_desired_npb(
+ struct xfs_btree_cur *cur,
+ struct xfs_btree_bload *bbl,
+ unsigned int level)
+{
+ unsigned int npb = xfs_btree_bload_max_npb(cur, bbl, level);
+
+ /* Root blocks are not subject to minrecs rules. */
+ if (level == cur->bc_nlevels - 1)
+ return max(1U, npb);
+
+ return max_t(unsigned int, cur->bc_ops->get_minrecs(cur, level), npb);
+}
+
+/*
+ * Compute the number of records to be stored in each block at this level and
+ * the number of blocks for this level. For leaf levels, we must populate an
+ * empty root block even if there are no records, so we have to have at least
+ * one block.
+ */
+STATIC void
+xfs_btree_bload_level_geometry(
+ struct xfs_btree_cur *cur,
+ struct xfs_btree_bload *bbl,
+ unsigned int level,
+ uint64_t nr_this_level,
+ unsigned int *avg_per_block,
+ uint64_t *blocks,
+ uint64_t *blocks_with_extra)
+{
+ uint64_t npb;
+ uint64_t dontcare;
+ unsigned int desired_npb;
+ unsigned int maxnr;
+
+ maxnr = cur->bc_ops->get_maxrecs(cur, level);
+
+ /*
+ * Compute the number of blocks we need to fill each block with the
+ * desired number of records/keyptrs per block. Because desired_npb
+ * could be minrecs, we use regular integer division (which rounds
+ * the block count down) so that in the next step the effective # of
+ * items per block will never be less than desired_npb.
+ */
+ desired_npb = xfs_btree_bload_desired_npb(cur, bbl, level);
+ *blocks = div64_u64_rem(nr_this_level, desired_npb, &dontcare);
+ *blocks = max(1ULL, *blocks);
+
+ /*
+ * Compute the number of records that we will actually put in each
+ * block, assuming that we want to spread the records evenly between
+ * the blocks. Take care that the effective # of items per block (npb)
+ * won't exceed maxrecs even for the blocks that get an extra record,
+ * since desired_npb could be maxrecs, and in the previous step we
+ * rounded the block count down.
+ */
+ npb = div64_u64_rem(nr_this_level, *blocks, blocks_with_extra);
+ if (npb > maxnr || (npb == maxnr && *blocks_with_extra > 0)) {
+ (*blocks)++;
+ npb = div64_u64_rem(nr_this_level, *blocks, blocks_with_extra);
+ }
+
+ *avg_per_block = min_t(uint64_t, npb, nr_this_level);
+
+ trace_xfs_btree_bload_level_geometry(cur, level, nr_this_level,
+ *avg_per_block, desired_npb, *blocks,
+ *blocks_with_extra);
+}
+
+/*
+ * Ensure a slack value is appropriate for the btree.
+ *
+ * If the slack value is negative, set slack so that we fill the block to
+ * halfway between minrecs and maxrecs. Make sure the slack is never so large
+ * that we can underflow minrecs.
+ */
+static void
+xfs_btree_bload_ensure_slack(
+ struct xfs_btree_cur *cur,
+ int *slack,
+ int level)
+{
+ int maxr;
+ int minr;
+
+ maxr = cur->bc_ops->get_maxrecs(cur, level);
+ minr = cur->bc_ops->get_minrecs(cur, level);
+
+ /*
+ * If slack is negative, automatically set slack so that we load the
+ * btree block approximately halfway between minrecs and maxrecs.
+ * Generally, this will net us 75% loading.
+ */
+ if (*slack < 0)
+ *slack = maxr - ((maxr + minr) >> 1);
+
+ *slack = min(*slack, maxr - minr);
+}
+
+/*
+ * Prepare a btree cursor for a bulk load operation by computing the geometry
+ * fields in bbl. Caller must ensure that the btree cursor is a staging
+ * cursor. This function can be called multiple times.
+ */
+int
+xfs_btree_bload_compute_geometry(
+ struct xfs_btree_cur *cur,
+ struct xfs_btree_bload *bbl,
+ uint64_t nr_records)
+{
+ uint64_t nr_blocks = 0;
+ uint64_t nr_this_level;
+
+ ASSERT(cur->bc_flags & XFS_BTREE_STAGING);
+
+ /*
+ * Make sure that the slack values make sense for traditional leaf and
+ * node blocks. Inode-rooted btrees will return different minrecs and
+ * maxrecs values for the root block (bc_nlevels == level - 1). We're
+ * checking levels 0 and 1 here, so set bc_nlevels such that the btree
+ * code doesn't interpret either as the root level.
+ */
+ cur->bc_nlevels = XFS_BTREE_MAXLEVELS - 1;
+ xfs_btree_bload_ensure_slack(cur, &bbl->leaf_slack, 0);
+ xfs_btree_bload_ensure_slack(cur, &bbl->node_slack, 1);
+
+ bbl->nr_records = nr_this_level = nr_records;
+ for (cur->bc_nlevels = 1; cur->bc_nlevels < XFS_BTREE_MAXLEVELS;) {
+ uint64_t level_blocks;
+ uint64_t dontcare64;
+ unsigned int level = cur->bc_nlevels - 1;
+ unsigned int avg_per_block;
+
+ xfs_btree_bload_level_geometry(cur, bbl, level, nr_this_level,
+ &avg_per_block, &level_blocks, &dontcare64);
+
+ if (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) {
+ /*
+ * If all the items we want to store at this level
+ * would fit in the inode root block, then we have our
+ * btree root and are done.
+ *
+ * Note that bmap btrees forbid records in the root.
+ */
+ if (level != 0 && nr_this_level <= avg_per_block) {
+ nr_blocks++;
+ break;
+ }
+
+ /*
+ * Otherwise, we have to store all the items for this
+ * level in traditional btree blocks and therefore need
+ * another level of btree to point to those blocks.
+ *
+ * We have to re-compute the geometry for each level of
+ * an inode-rooted btree because the geometry differs
+ * between a btree root in an inode fork and a
+ * traditional btree block.
+ *
+ * This distinction is made in the btree code based on
+ * whether level == bc_nlevels - 1. Based on the
+ * previous root block size check against the root
+ * block geometry, we know that we aren't yet ready to
+ * populate the root. Increment bc_nevels and
+ * recalculate the geometry for a traditional
+ * block-based btree level.
+ */
+ cur->bc_nlevels++;
+ xfs_btree_bload_level_geometry(cur, bbl, level,
+ nr_this_level, &avg_per_block,
+ &level_blocks, &dontcare64);
+ } else {
+ /*
+ * If all the items we want to store at this level
+ * would fit in a single root block, we're done.
+ */
+ if (nr_this_level <= avg_per_block) {
+ nr_blocks++;
+ break;
+ }
+
+ /* Otherwise, we need another level of btree. */
+ cur->bc_nlevels++;
+ }
+
+ nr_blocks += level_blocks;
+ nr_this_level = level_blocks;
+ }
+
+ if (cur->bc_nlevels == XFS_BTREE_MAXLEVELS)
+ return -EOVERFLOW;
+
+ bbl->btree_height = cur->bc_nlevels;
+ if (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE)
+ bbl->nr_blocks = nr_blocks - 1;
+ else
+ bbl->nr_blocks = nr_blocks;
+ return 0;
+}
+
+/* Bulk load a btree given the parameters and geometry established in bbl. */
+int
+xfs_btree_bload(
+ struct xfs_btree_cur *cur,
+ struct xfs_btree_bload *bbl,
+ void *priv)
+{
+ struct list_head buffers_list;
+ union xfs_btree_ptr child_ptr;
+ union xfs_btree_ptr ptr;
+ struct xfs_buf *bp = NULL;
+ struct xfs_btree_block *block = NULL;
+ uint64_t nr_this_level = bbl->nr_records;
+ uint64_t blocks;
+ uint64_t i;
+ uint64_t blocks_with_extra;
+ uint64_t total_blocks = 0;
+ unsigned int avg_per_block;
+ unsigned int level = 0;
+ int ret;
+
+ ASSERT(cur->bc_flags & XFS_BTREE_STAGING);
+
+ INIT_LIST_HEAD(&buffers_list);
+ cur->bc_nlevels = bbl->btree_height;
+ xfs_btree_set_ptr_null(cur, &child_ptr);
+ xfs_btree_set_ptr_null(cur, &ptr);
+
+ xfs_btree_bload_level_geometry(cur, bbl, level, nr_this_level,
+ &avg_per_block, &blocks, &blocks_with_extra);
+
+ /* Load each leaf block. */
+ for (i = 0; i < blocks; i++) {
+ unsigned int nr_this_block = avg_per_block;
+
+ /*
+ * Due to rounding, btree blocks will not be evenly populated
+ * in most cases. blocks_with_extra tells us how many blocks
+ * will receive an extra record to distribute the excess across
+ * the current level as evenly as possible.
+ */
+ if (i < blocks_with_extra)
+ nr_this_block++;
+
+ ret = xfs_btree_bload_prep_block(cur, bbl, &buffers_list, level,
+ nr_this_block, &ptr, &bp, &block, priv);
+ if (ret)
+ goto out;
+
+ trace_xfs_btree_bload_block(cur, level, i, blocks, &ptr,
+ nr_this_block);
+
+ ret = xfs_btree_bload_leaf(cur, nr_this_block, bbl->get_record,
+ block, priv);
+ if (ret)
+ goto out;
+
+ /*
+ * Record the leftmost leaf pointer so we know where to start
+ * with the first node level.
+ */
+ if (i == 0)
+ xfs_btree_copy_ptrs(cur, &child_ptr, &ptr, 1);
+ }
+ total_blocks += blocks;
+ xfs_btree_bload_drop_buf(&buffers_list, &bp);
+
+ /* Populate the internal btree nodes. */
+ for (level = 1; level < cur->bc_nlevels; level++) {
+ union xfs_btree_ptr first_ptr;
+
+ nr_this_level = blocks;
+ block = NULL;
+ xfs_btree_set_ptr_null(cur, &ptr);
+
+ xfs_btree_bload_level_geometry(cur, bbl, level, nr_this_level,
+ &avg_per_block, &blocks, &blocks_with_extra);
+
+ /* Load each node block. */
+ for (i = 0; i < blocks; i++) {
+ unsigned int nr_this_block = avg_per_block;
+
+ if (i < blocks_with_extra)
+ nr_this_block++;
+
+ ret = xfs_btree_bload_prep_block(cur, bbl,
+ &buffers_list, level, nr_this_block,
+ &ptr, &bp, &block, priv);
+ if (ret)
+ goto out;
+
+ trace_xfs_btree_bload_block(cur, level, i, blocks,
+ &ptr, nr_this_block);
+
+ ret = xfs_btree_bload_node(cur, nr_this_block,
+ &child_ptr, block);
+ if (ret)
+ goto out;
+
+ /*
+ * Record the leftmost node pointer so that we know
+ * where to start the next node level above this one.
+ */
+ if (i == 0)
+ xfs_btree_copy_ptrs(cur, &first_ptr, &ptr, 1);
+ }
+ total_blocks += blocks;
+ xfs_btree_bload_drop_buf(&buffers_list, &bp);
+ xfs_btree_copy_ptrs(cur, &child_ptr, &first_ptr, 1);
+ }
+
+ /* Initialize the new root. */
+ if (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) {
+ ASSERT(xfs_btree_ptr_is_null(cur, &ptr));
+ cur->bc_ino.ifake->if_levels = cur->bc_nlevels;
+ cur->bc_ino.ifake->if_blocks = total_blocks - 1;
+ } else {
+ cur->bc_ag.afake->af_root = be32_to_cpu(ptr.s);
+ cur->bc_ag.afake->af_levels = cur->bc_nlevels;
+ cur->bc_ag.afake->af_blocks = total_blocks;
+ }
+
+ /*
+ * Write the new blocks to disk. If the ordered list isn't empty after
+ * that, then something went wrong and we have to fail. This should
+ * never happen, but we'll check anyway.
+ */
+ ret = xfs_buf_delwri_submit(&buffers_list);
+ if (ret)
+ goto out;
+ if (!list_empty(&buffers_list)) {
+ ASSERT(list_empty(&buffers_list));
+ ret = -EIO;
+ }
+
+out:
+ xfs_buf_delwri_cancel(&buffers_list);
+ if (bp)
+ xfs_buf_relse(bp);
+ return ret;
+}
projects / users / hch / xfs.git / commitdiff