xfs_da_btree.c

linux 内核源代码

/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_da_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_inode_item.h"
#include "xfs_alloc.h"
#include "xfs_btree.h"
#include "xfs_bmap.h"
#include "xfs_attr.h"
#include "xfs_attr_leaf.h"
#include "xfs_dir2_data.h"
#include "xfs_dir2_leaf.h"
#include "xfs_dir2_block.h"
#include "xfs_dir2_node.h"
#include "xfs_error.h"

/*
 * xfs_da_btree.c
 *
 * Routines to implement directories as Btrees of hashed names.
 */

/*========================================================================
 * Function prototypes for the kernel.
 *========================================================================*/

/*
 * Routines used for growing the Btree.
 */
STATIC int xfs_da_root_split(xfs_da_state_t *state,
					    xfs_da_state_blk_t *existing_root,
					    xfs_da_state_blk_t *new_child);
STATIC int xfs_da_node_split(xfs_da_state_t *state,
					    xfs_da_state_blk_t *existing_blk,
					    xfs_da_state_blk_t *split_blk,
					    xfs_da_state_blk_t *blk_to_add,
					    int treelevel,
					    int *result);
STATIC void xfs_da_node_rebalance(xfs_da_state_t *state,
					 xfs_da_state_blk_t *node_blk_1,
					 xfs_da_state_blk_t *node_blk_2);
STATIC void xfs_da_node_add(xfs_da_state_t *state,
				   xfs_da_state_blk_t *old_node_blk,
				   xfs_da_state_blk_t *new_node_blk);

/*
 * Routines used for shrinking the Btree.
 */
STATIC int xfs_da_root_join(xfs_da_state_t *state,
					   xfs_da_state_blk_t *root_blk);
STATIC int xfs_da_node_toosmall(xfs_da_state_t *state, int *retval);
STATIC void xfs_da_node_remove(xfs_da_state_t *state,
					      xfs_da_state_blk_t *drop_blk);
STATIC void xfs_da_node_unbalance(xfs_da_state_t *state,
					 xfs_da_state_blk_t *src_node_blk,
					 xfs_da_state_blk_t *dst_node_blk);

/*
 * Utility routines.
 */
STATIC uint	xfs_da_node_lasthash(xfs_dabuf_t *bp, int *count);
STATIC int	xfs_da_node_order(xfs_dabuf_t *node1_bp, xfs_dabuf_t *node2_bp);
STATIC xfs_dabuf_t *xfs_da_buf_make(int nbuf, xfs_buf_t **bps, inst_t *ra);
STATIC int	xfs_da_blk_unlink(xfs_da_state_t *state,
				  xfs_da_state_blk_t *drop_blk,
				  xfs_da_state_blk_t *save_blk);
STATIC void	xfs_da_state_kill_altpath(xfs_da_state_t *state);

/*========================================================================
 * Routines used for growing the Btree.
 *========================================================================*/

/*
 * Create the initial contents of an intermediate node.
 */
int
xfs_da_node_create(xfs_da_args_t *args, xfs_dablk_t blkno, int level,
				 xfs_dabuf_t **bpp, int whichfork)
{
	xfs_da_intnode_t *node;
	xfs_dabuf_t *bp;
	int error;
	xfs_trans_t *tp;

	tp = args->trans;
	error = xfs_da_get_buf(tp, args->dp, blkno, -1, &bp, whichfork);
	if (error)
		return(error);
	ASSERT(bp != NULL);
	node = bp->data;
	node->hdr.info.forw = 0;
	node->hdr.info.back = 0;
	node->hdr.info.magic = cpu_to_be16(XFS_DA_NODE_MAGIC);
	node->hdr.info.pad = 0;
	node->hdr.count = 0;
	node->hdr.level = cpu_to_be16(level);

	xfs_da_log_buf(tp, bp,
		XFS_DA_LOGRANGE(node, &node->hdr, sizeof(node->hdr)));

	*bpp = bp;
	return(0);
}

/*
 * Split a leaf node, rebalance, then possibly split
 * intermediate nodes, rebalance, etc.
 */
int							/* error */
xfs_da_split(xfs_da_state_t *state)
{
	xfs_da_state_blk_t *oldblk, *newblk, *addblk;
	xfs_da_intnode_t *node;
	xfs_dabuf_t *bp;
	int max, action, error, i;

	/*
	 * Walk back up the tree splitting/inserting/adjusting as necessary.
	 * If we need to insert and there isn't room, split the node, then
	 * decide which fragment to insert the new block from below into.
	 * Note that we may split the root this way, but we need more fixup.
	 */
	max = state->path.active - 1;
	ASSERT((max >= 0) && (max < XFS_DA_NODE_MAXDEPTH));
	ASSERT(state->path.blk[max].magic == XFS_ATTR_LEAF_MAGIC ||
	       state->path.blk[max].magic == XFS_DIR2_LEAFN_MAGIC);

	addblk = &state->path.blk[max];		/* initial dummy value */
	for (i = max; (i >= 0) && addblk; state->path.active--, i--) {
		oldblk = &state->path.blk[i];
		newblk = &state->altpath.blk[i];

		/*
		 * If a leaf node then
		 *     Allocate a new leaf node, then rebalance across them.
		 * else if an intermediate node then
		 *     We split on the last layer, must we split the node?
		 */
		switch (oldblk->magic) {
		case XFS_ATTR_LEAF_MAGIC:
			error = xfs_attr_leaf_split(state, oldblk, newblk);
			if ((error != 0) && (error != ENOSPC)) {
				return(error);	/* GROT: attr is inconsistent */
			}
			if (!error) {
				addblk = newblk;
				break;
			}
			/*
			 * Entry wouldn't fit, split the leaf again.
			 */
			state->extravalid = 1;
			if (state->inleaf) {
				state->extraafter = 0;	/* before newblk */
				error = xfs_attr_leaf_split(state, oldblk,
							    &state->extrablk);
			} else {
				state->extraafter = 1;	/* after newblk */
				error = xfs_attr_leaf_split(state, newblk,
							    &state->extrablk);
			}
			if (error)
				return(error);	/* GROT: attr inconsistent */
			addblk = newblk;
			break;
		case XFS_DIR2_LEAFN_MAGIC:
			error = xfs_dir2_leafn_split(state, oldblk, newblk);
			if (error)
				return error;
			addblk = newblk;
			break;
		case XFS_DA_NODE_MAGIC:
			error = xfs_da_node_split(state, oldblk, newblk, addblk,
							 max - i, &action);
			xfs_da_buf_done(addblk->bp);
			addblk->bp = NULL;
			if (error)
				return(error);	/* GROT: dir is inconsistent */
			/*
			 * Record the newly split block for the next time thru?
			 */
			if (action)
				addblk = newblk;
			else
				addblk = NULL;
			break;
		}

		/*
		 * Update the btree to show the new hashval for this child.
		 */
		xfs_da_fixhashpath(state, &state->path);
		/*
		 * If we won't need this block again, it's getting dropped
		 * from the active path by the loop control, so we need
		 * to mark it done now.
		 */
		if (i > 0 || !addblk)
			xfs_da_buf_done(oldblk->bp);
	}
	if (!addblk)
		return(0);

	/*
	 * Split the root node.
	 */
	ASSERT(state->path.active == 0);
	oldblk = &state->path.blk[0];
	error = xfs_da_root_split(state, oldblk, addblk);
	if (error) {
		xfs_da_buf_done(oldblk->bp);
		xfs_da_buf_done(addblk->bp);
		addblk->bp = NULL;
		return(error);	/* GROT: dir is inconsistent */
	}

	/*
	 * Update pointers to the node which used to be block 0 and
	 * just got bumped because of the addition of a new root node.
	 * There might be three blocks involved if a double split occurred,
	 * and the original block 0 could be at any position in the list.
	 */

	node = oldblk->bp->data;
	if (node->hdr.info.forw) {
		if (be32_to_cpu(node->hdr.info.forw) == addblk->blkno) {
			bp = addblk->bp;
		} else {
			ASSERT(state->extravalid);
			bp = state->extrablk.bp;
		}
		node = bp->data;
		node->hdr.info.back = cpu_to_be32(oldblk->blkno);
		xfs_da_log_buf(state->args->trans, bp,
		    XFS_DA_LOGRANGE(node, &node->hdr.info,
		    sizeof(node->hdr.info)));
	}
	node = oldblk->bp->data;
	if (node->hdr.info.back) {
		if (be32_to_cpu(node->hdr.info.back) == addblk->blkno) {
			bp = addblk->bp;
		} else {
			ASSERT(state->extravalid);
			bp = state->extrablk.bp;
		}
		node = bp->data;
		node->hdr.info.forw = cpu_to_be32(oldblk->blkno);
		xfs_da_log_buf(state->args->trans, bp,
		    XFS_DA_LOGRANGE(node, &node->hdr.info,
		    sizeof(node->hdr.info)));
	}
	xfs_da_buf_done(oldblk->bp);
	xfs_da_buf_done(addblk->bp);
	addblk->bp = NULL;
	return(0);
}

/*
 * Split the root.  We have to create a new root and point to the two
 * parts (the split old root) that we just created.  Copy block zero to
 * the EOF, extending the inode in process.
 */
STATIC int						/* error */
xfs_da_root_split(xfs_da_state_t *state, xfs_da_state_blk_t *blk1,
				 xfs_da_state_blk_t *blk2)
{
	xfs_da_intnode_t *node, *oldroot;
	xfs_da_args_t *args;
	xfs_dablk_t blkno;
	xfs_dabuf_t *bp;
	int error, size;
	xfs_inode_t *dp;
	xfs_trans_t *tp;
	xfs_mount_t *mp;
	xfs_dir2_leaf_t *leaf;

	/*
	 * Copy the existing (incorrect) block from the root node position
	 * to a free space somewhere.
	 */
	args = state->args;
	ASSERT(args != NULL);
	error = xfs_da_grow_inode(args, &blkno);
	if (error)
		return(error);
	dp = args->dp;
	tp = args->trans;
	mp = state->mp;
	error = xfs_da_get_buf(tp, dp, blkno, -1, &bp, args->whichfork);
	if (error)
		return(error);
	ASSERT(bp != NULL);
	node = bp->data;
	oldroot = blk1->bp->data;
	if (be16_to_cpu(oldroot->hdr.info.magic) == XFS_DA_NODE_MAGIC) {
		size = (int)((char *)&oldroot->btree[be16_to_cpu(oldroot->hdr.count)] -
			     (char *)oldroot);
	} else {
		ASSERT(be16_to_cpu(oldroot->hdr.info.magic) == XFS_DIR2_LEAFN_MAGIC);
		leaf = (xfs_dir2_leaf_t *)oldroot;
		size = (int)((char *)&leaf->ents[be16_to_cpu(leaf->hdr.count)] -
			     (char *)leaf);
	}
	memcpy(node, oldroot, size);
	xfs_da_log_buf(tp, bp, 0, size - 1);
	xfs_da_buf_done(blk1->bp);
	blk1->bp = bp;
	blk1->blkno = blkno;

	/*
	 * Set up the new root node.
	 */
	error = xfs_da_node_create(args,
		(args->whichfork == XFS_DATA_FORK) ? mp->m_dirleafblk : 0,
		be16_to_cpu(node->hdr.level) + 1, &bp, args->whichfork);
	if (error)
		return(error);
	node = bp->data;
	node->btree[0].hashval = cpu_to_be32(blk1->hashval);
	node->btree[0].before = cpu_to_be32(blk1->blkno);
	node->btree[1].hashval = cpu_to_be32(blk2->hashval);
	node->btree[1].before = cpu_to_be32(blk2->blkno);
	node->hdr.count = cpu_to_be16(2);

#ifdef DEBUG
	if (be16_to_cpu(oldroot->hdr.info.magic) == XFS_DIR2_LEAFN_MAGIC) {
		ASSERT(blk1->blkno >= mp->m_dirleafblk &&
		       blk1->blkno < mp->m_dirfreeblk);
		ASSERT(blk2->blkno >= mp->m_dirleafblk &&
		       blk2->blkno < mp->m_dirfreeblk);
	}
#endif

	/* Header is already logged by xfs_da_node_create */
	xfs_da_log_buf(tp, bp,
		XFS_DA_LOGRANGE(node, node->btree,
			sizeof(xfs_da_node_entry_t) * 2));
	xfs_da_buf_done(bp);

	return(0);
}

/*
 * Split the node, rebalance, then add the new entry.
 */
STATIC int						/* error */
xfs_da_node_split(xfs_da_state_t *state, xfs_da_state_blk_t *oldblk,
				 xfs_da_state_blk_t *newblk,
				 xfs_da_state_blk_t *addblk,
				 int treelevel, int *result)
{
	xfs_da_intnode_t *node;
	xfs_dablk_t blkno;
	int newcount, error;
	int useextra;

	node = oldblk->bp->data;
	ASSERT(be16_to_cpu(node->hdr.info.magic) == XFS_DA_NODE_MAGIC);

	/*
	 * With V2 dirs the extra block is data or freespace.
	 */
	useextra = state->extravalid && state->args->whichfork == XFS_ATTR_FORK;
	newcount = 1 + useextra;
	/*
	 * Do we have to split the node?
	 */
	if ((be16_to_cpu(node->hdr.count) + newcount) > state->node_ents) {
		/*
		 * Allocate a new node, add to the doubly linked chain of
		 * nodes, then move some of our excess entries into it.
		 */
		error = xfs_da_grow_inode(state->args, &blkno);
		if (error)
			return(error);	/* GROT: dir is inconsistent */

		error = xfs_da_node_create(state->args, blkno, treelevel,
					   &newblk->bp, state->args->whichfork);
		if (error)
			return(error);	/* GROT: dir is inconsistent */
		newblk->blkno = blkno;
		newblk->magic = XFS_DA_NODE_MAGIC;
		xfs_da_node_rebalance(state, oldblk, newblk);
		error = xfs_da_blk_link(state, oldblk, newblk);
		if (error)
			return(error);
		*result = 1;
	} else {
		*result = 0;
	}

	/*
	 * Insert the new entry(s) into the correct block
	 * (updating last hashval in the process).
	 *
	 * xfs_da_node_add() inserts BEFORE the given index,
	 * and as a result of using node_lookup_int() we always
	 * point to a valid entry (not after one), but a split
	 * operation always results in a new block whose hashvals
	 * FOLLOW the current block.
	 *
	 * If we had double-split op below us, then add the extra block too.
	 */
	node = oldblk->bp->data;
	if (oldblk->index <= be16_to_cpu(node->hdr.count)) {
		oldblk->index++;
		xfs_da_node_add(state, oldblk, addblk);
		if (useextra) {
			if (state->extraafter)
				oldblk->index++;
			xfs_da_node_add(state, oldblk, &state->extrablk);
			state->extravalid = 0;
		}
	} else {
		newblk->index++;
		xfs_da_node_add(state, newblk, addblk);
		if (useextra) {
			if (state->extraafter)
				newblk->index++;
			xfs_da_node_add(state, newblk, &state->extrablk);
			state->extravalid = 0;
		}
	}

	return(0);
}

/*
 * Balance the btree elements between two intermediate nodes,
 * usually one full and one empty.
 *
 * NOTE: if blk2 is empty, then it will get the upper half of blk1.
 */
STATIC void
xfs_da_node_rebalance(xfs_da_state_t *state, xfs_da_state_blk_t *blk1,
				     xfs_da_state_blk_t *blk2)
{
	xfs_da_intnode_t *node1, *node2, *tmpnode;
	xfs_da_node_entry_t *btree_s, *btree_d;
	int count, tmp;
	xfs_trans_t *tp;