xfs_attr_leaf.c

linux 内核源代码

{
	xfs_attr_leafblock_t *leaf;
	xfs_da_intnode_t *node;
	xfs_inode_t *dp;
	xfs_dabuf_t *bp1, *bp2;
	xfs_dablk_t blkno;
	int error;

	dp = args->dp;
	bp1 = bp2 = NULL;
	error = xfs_da_grow_inode(args, &blkno);
	if (error)
		goto out;
	error = xfs_da_read_buf(args->trans, args->dp, 0, -1, &bp1,
					     XFS_ATTR_FORK);
	if (error)
		goto out;
	ASSERT(bp1 != NULL);
	bp2 = NULL;
	error = xfs_da_get_buf(args->trans, args->dp, blkno, -1, &bp2,
					    XFS_ATTR_FORK);
	if (error)
		goto out;
	ASSERT(bp2 != NULL);
	memcpy(bp2->data, bp1->data, XFS_LBSIZE(dp->i_mount));
	xfs_da_buf_done(bp1);
	bp1 = NULL;
	xfs_da_log_buf(args->trans, bp2, 0, XFS_LBSIZE(dp->i_mount) - 1);

	/*
	 * Set up the new root node.
	 */
	error = xfs_da_node_create(args, 0, 1, &bp1, XFS_ATTR_FORK);
	if (error)
		goto out;
	node = bp1->data;
	leaf = bp2->data;
	ASSERT(be16_to_cpu(leaf->hdr.info.magic) == XFS_ATTR_LEAF_MAGIC);
	/* both on-disk, don't endian-flip twice */
	node->btree[0].hashval =
		leaf->entries[be16_to_cpu(leaf->hdr.count)-1 ].hashval;
	node->btree[0].before = cpu_to_be32(blkno);
	node->hdr.count = cpu_to_be16(1);
	xfs_da_log_buf(args->trans, bp1, 0, XFS_LBSIZE(dp->i_mount) - 1);
	error = 0;
out:
	if (bp1)
		xfs_da_buf_done(bp1);
	if (bp2)
		xfs_da_buf_done(bp2);
	return(error);
}


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

/*
 * Create the initial contents of a leaf attribute list
 * or a leaf in a node attribute list.
 */
STATIC int
xfs_attr_leaf_create(xfs_da_args_t *args, xfs_dablk_t blkno, xfs_dabuf_t **bpp)
{
	xfs_attr_leafblock_t *leaf;
	xfs_attr_leaf_hdr_t *hdr;
	xfs_inode_t *dp;
	xfs_dabuf_t *bp;
	int error;

	dp = args->dp;
	ASSERT(dp != NULL);
	error = xfs_da_get_buf(args->trans, args->dp, blkno, -1, &bp,
					    XFS_ATTR_FORK);
	if (error)
		return(error);
	ASSERT(bp != NULL);
	leaf = bp->data;
	memset((char *)leaf, 0, XFS_LBSIZE(dp->i_mount));
	hdr = &leaf->hdr;
	hdr->info.magic = cpu_to_be16(XFS_ATTR_LEAF_MAGIC);
	hdr->firstused = cpu_to_be16(XFS_LBSIZE(dp->i_mount));
	if (!hdr->firstused) {
		hdr->firstused = cpu_to_be16(
			XFS_LBSIZE(dp->i_mount) - XFS_ATTR_LEAF_NAME_ALIGN);
	}

	hdr->freemap[0].base = cpu_to_be16(sizeof(xfs_attr_leaf_hdr_t));
	hdr->freemap[0].size = cpu_to_be16(be16_to_cpu(hdr->firstused) -
					   sizeof(xfs_attr_leaf_hdr_t));

	xfs_da_log_buf(args->trans, bp, 0, XFS_LBSIZE(dp->i_mount) - 1);

	*bpp = bp;
	return(0);
}

/*
 * Split the leaf node, rebalance, then add the new entry.
 */
int
xfs_attr_leaf_split(xfs_da_state_t *state, xfs_da_state_blk_t *oldblk,
				   xfs_da_state_blk_t *newblk)
{
	xfs_dablk_t blkno;
	int error;

	/*
	 * Allocate space for a new leaf node.
	 */
	ASSERT(oldblk->magic == XFS_ATTR_LEAF_MAGIC);
	error = xfs_da_grow_inode(state->args, &blkno);
	if (error)
		return(error);
	error = xfs_attr_leaf_create(state->args, blkno, &newblk->bp);
	if (error)
		return(error);
	newblk->blkno = blkno;
	newblk->magic = XFS_ATTR_LEAF_MAGIC;

	/*
	 * Rebalance the entries across the two leaves.
	 * NOTE: rebalance() currently depends on the 2nd block being empty.
	 */
	xfs_attr_leaf_rebalance(state, oldblk, newblk);
	error = xfs_da_blk_link(state, oldblk, newblk);
	if (error)
		return(error);

	/*
	 * Save info on "old" attribute for "atomic rename" ops, leaf_add()
	 * modifies the index/blkno/rmtblk/rmtblkcnt fields to show the
	 * "new" attrs info.  Will need the "old" info to remove it later.
	 *
	 * Insert the "new" entry in the correct block.
	 */
	if (state->inleaf)
		error = xfs_attr_leaf_add(oldblk->bp, state->args);
	else
		error = xfs_attr_leaf_add(newblk->bp, state->args);

	/*
	 * Update last hashval in each block since we added the name.
	 */
	oldblk->hashval = xfs_attr_leaf_lasthash(oldblk->bp, NULL);
	newblk->hashval = xfs_attr_leaf_lasthash(newblk->bp, NULL);
	return(error);
}

/*
 * Add a name to the leaf attribute list structure.
 */
int
xfs_attr_leaf_add(xfs_dabuf_t *bp, xfs_da_args_t *args)
{
	xfs_attr_leafblock_t *leaf;
	xfs_attr_leaf_hdr_t *hdr;
	xfs_attr_leaf_map_t *map;
	int tablesize, entsize, sum, tmp, i;

	leaf = bp->data;
	ASSERT(be16_to_cpu(leaf->hdr.info.magic) == XFS_ATTR_LEAF_MAGIC);
	ASSERT((args->index >= 0)
		&& (args->index <= be16_to_cpu(leaf->hdr.count)));
	hdr = &leaf->hdr;
	entsize = xfs_attr_leaf_newentsize(args->namelen, args->valuelen,
			   args->trans->t_mountp->m_sb.sb_blocksize, NULL);

	/*
	 * Search through freemap for first-fit on new name length.
	 * (may need to figure in size of entry struct too)
	 */
	tablesize = (be16_to_cpu(hdr->count) + 1)
					* sizeof(xfs_attr_leaf_entry_t)
					+ sizeof(xfs_attr_leaf_hdr_t);
	map = &hdr->freemap[XFS_ATTR_LEAF_MAPSIZE-1];
	for (sum = 0, i = XFS_ATTR_LEAF_MAPSIZE-1; i >= 0; map--, i--) {
		if (tablesize > be16_to_cpu(hdr->firstused)) {
			sum += be16_to_cpu(map->size);
			continue;
		}
		if (!map->size)
			continue;	/* no space in this map */
		tmp = entsize;
		if (be16_to_cpu(map->base) < be16_to_cpu(hdr->firstused))
			tmp += sizeof(xfs_attr_leaf_entry_t);
		if (be16_to_cpu(map->size) >= tmp) {
			tmp = xfs_attr_leaf_add_work(bp, args, i);
			return(tmp);
		}
		sum += be16_to_cpu(map->size);
	}

	/*
	 * If there are no holes in the address space of the block,
	 * and we don't have enough freespace, then compaction will do us
	 * no good and we should just give up.
	 */
	if (!hdr->holes && (sum < entsize))
		return(XFS_ERROR(ENOSPC));

	/*
	 * Compact the entries to coalesce free space.
	 * This may change the hdr->count via dropping INCOMPLETE entries.
	 */
	xfs_attr_leaf_compact(args->trans, bp);

	/*
	 * After compaction, the block is guaranteed to have only one
	 * free region, in freemap[0].  If it is not big enough, give up.
	 */
	if (be16_to_cpu(hdr->freemap[0].size)
				< (entsize + sizeof(xfs_attr_leaf_entry_t)))
		return(XFS_ERROR(ENOSPC));

	return(xfs_attr_leaf_add_work(bp, args, 0));
}

/*
 * Add a name to a leaf attribute list structure.
 */
STATIC int
xfs_attr_leaf_add_work(xfs_dabuf_t *bp, xfs_da_args_t *args, int mapindex)
{
	xfs_attr_leafblock_t *leaf;
	xfs_attr_leaf_hdr_t *hdr;
	xfs_attr_leaf_entry_t *entry;
	xfs_attr_leaf_name_local_t *name_loc;
	xfs_attr_leaf_name_remote_t *name_rmt;
	xfs_attr_leaf_map_t *map;
	xfs_mount_t *mp;
	int tmp, i;

	leaf = bp->data;
	ASSERT(be16_to_cpu(leaf->hdr.info.magic) == XFS_ATTR_LEAF_MAGIC);
	hdr = &leaf->hdr;
	ASSERT((mapindex >= 0) && (mapindex < XFS_ATTR_LEAF_MAPSIZE));
	ASSERT((args->index >= 0) && (args->index <= be16_to_cpu(hdr->count)));

	/*
	 * Force open some space in the entry array and fill it in.
	 */
	entry = &leaf->entries[args->index];
	if (args->index < be16_to_cpu(hdr->count)) {
		tmp  = be16_to_cpu(hdr->count) - args->index;
		tmp *= sizeof(xfs_attr_leaf_entry_t);
		memmove((char *)(entry+1), (char *)entry, tmp);
		xfs_da_log_buf(args->trans, bp,
		    XFS_DA_LOGRANGE(leaf, entry, tmp + sizeof(*entry)));
	}
	be16_add(&hdr->count, 1);

	/*
	 * Allocate space for the new string (at the end of the run).
	 */
	map = &hdr->freemap[mapindex];
	mp = args->trans->t_mountp;
	ASSERT(be16_to_cpu(map->base) < XFS_LBSIZE(mp));
	ASSERT((be16_to_cpu(map->base) & 0x3) == 0);
	ASSERT(be16_to_cpu(map->size) >=
		xfs_attr_leaf_newentsize(args->namelen, args->valuelen,
					 mp->m_sb.sb_blocksize, NULL));
	ASSERT(be16_to_cpu(map->size) < XFS_LBSIZE(mp));
	ASSERT((be16_to_cpu(map->size) & 0x3) == 0);
	be16_add(&map->size,
		-xfs_attr_leaf_newentsize(args->namelen, args->valuelen,
					  mp->m_sb.sb_blocksize, &tmp));
	entry->nameidx = cpu_to_be16(be16_to_cpu(map->base) +
				     be16_to_cpu(map->size));
	entry->hashval = cpu_to_be32(args->hashval);
	entry->flags = tmp ? XFS_ATTR_LOCAL : 0;
	entry->flags |= XFS_ATTR_NSP_ARGS_TO_ONDISK(args->flags);
	if (args->rename) {
		entry->flags |= XFS_ATTR_INCOMPLETE;
		if ((args->blkno2 == args->blkno) &&
		    (args->index2 <= args->index)) {
			args->index2++;
		}
	}
	xfs_da_log_buf(args->trans, bp,
			  XFS_DA_LOGRANGE(leaf, entry, sizeof(*entry)));
	ASSERT((args->index == 0) ||
	       (be32_to_cpu(entry->hashval) >= be32_to_cpu((entry-1)->hashval)));
	ASSERT((args->index == be16_to_cpu(hdr->count)-1) ||
	       (be32_to_cpu(entry->hashval) <= be32_to_cpu((entry+1)->hashval)));

	/*
	 * Copy the attribute name and value into the new space.
	 *
	 * For "remote" attribute values, simply note that we need to
	 * allocate space for the "remote" value.  We can't actually
	 * allocate the extents in this transaction, and we can't decide
	 * which blocks they should be as we might allocate more blocks
	 * as part of this transaction (a split operation for example).
	 */
	if (entry->flags & XFS_ATTR_LOCAL) {
		name_loc = XFS_ATTR_LEAF_NAME_LOCAL(leaf, args->index);
		name_loc->namelen = args->namelen;
		name_loc->valuelen = cpu_to_be16(args->valuelen);
		memcpy((char *)name_loc->nameval, args->name, args->namelen);
		memcpy((char *)&name_loc->nameval[args->namelen], args->value,
				   be16_to_cpu(name_loc->valuelen));
	} else {
		name_rmt = XFS_ATTR_LEAF_NAME_REMOTE(leaf, args->index);
		name_rmt->namelen = args->namelen;
		memcpy((char *)name_rmt->name, args->name, args->namelen);
		entry->flags |= XFS_ATTR_INCOMPLETE;
		/* just in case */
		name_rmt->valuelen = 0;
		name_rmt->valueblk = 0;
		args->rmtblkno = 1;
		args->rmtblkcnt = XFS_B_TO_FSB(mp, args->valuelen);
	}
	xfs_da_log_buf(args->trans, bp,
	     XFS_DA_LOGRANGE(leaf, XFS_ATTR_LEAF_NAME(leaf, args->index),
				   xfs_attr_leaf_entsize(leaf, args->index)));

	/*
	 * Update the control info for this leaf node
	 */
	if (be16_to_cpu(entry->nameidx) < be16_to_cpu(hdr->firstused)) {
		/* both on-disk, don't endian-flip twice */
		hdr->firstused = entry->nameidx;
	}
	ASSERT(be16_to_cpu(hdr->firstused) >=
	       ((be16_to_cpu(hdr->count) * sizeof(*entry)) + sizeof(*hdr)));
	tmp = (be16_to_cpu(hdr->count)-1) * sizeof(xfs_attr_leaf_entry_t)
					+ sizeof(xfs_attr_leaf_hdr_t);
	map = &hdr->freemap[0];
	for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; map++, i++) {
		if (be16_to_cpu(map->base) == tmp) {
			be16_add(&map->base, sizeof(xfs_attr_leaf_entry_t));
			be16_add(&map->size,
				 -((int)sizeof(xfs_attr_leaf_entry_t)));
		}
	}
	be16_add(&hdr->usedbytes, xfs_attr_leaf_entsize(leaf, args->index));
	xfs_da_log_buf(args->trans, bp,
		XFS_DA_LOGRANGE(leaf, hdr, sizeof(*hdr)));
	return(0);
}

/*
 * Garbage collect a leaf attribute list block by copying it to a new buffer.
 */
STATIC void
xfs_attr_leaf_compact(xfs_trans_t *trans, xfs_dabuf_t *bp)
{
	xfs_attr_leafblock_t *leaf_s, *leaf_d;
	xfs_attr_leaf_hdr_t *hdr_s, *hdr_d;
	xfs_mount_t *mp;
	char *tmpbuffer;

	mp = trans->t_mountp;
	tmpbuffer = kmem_alloc(XFS_LBSIZE(mp), KM_SLEEP);
	ASSERT(tmpbuffer != NULL);
	memcpy(tmpbuffer, bp->data, XFS_LBSIZE(mp));
	memset(bp->data, 0, XFS_LBSIZE(mp));

	/*
	 * Copy basic information
	 */
	leaf_s = (xfs_attr_leafblock_t *)tmpbuffer;
	leaf_d = bp->data;
	hdr_s = &leaf_s->hdr;
	hdr_d = &leaf_d->hdr;
	hdr_d->info = hdr_s->info;	/* struct copy */
	hdr_d->firstused = cpu_to_be16(XFS_LBSIZE(mp));
	/* handle truncation gracefully */
	if (!hdr_d->firstused) {
		hdr_d->firstused = cpu_to_be16(
				XFS_LBSIZE(mp) - XFS_ATTR_LEAF_NAME_ALIGN);
	}
	hdr_d->usedbytes = 0;
	hdr_d->count = 0;
	hdr_d->holes = 0;
	hdr_d->freemap[0].base = cpu_to_be16(sizeof(xfs_attr_leaf_hdr_t));
	hdr_d->freemap[0].size = cpu_to_be16(be16_to_cpu(hdr_d->firstused) -
					     sizeof(xfs_attr_leaf_hdr_t));

	/*
	 * Copy all entry's in the same (sorted) order,
	 * but allocate name/value pairs packed and in sequence.
	 */
	xfs_attr_leaf_moveents(leaf_s, 0, leaf_d, 0,
				be16_to_cpu(hdr_s->count), mp);
	xfs_da_log_buf(trans, bp, 0, XFS_LBSIZE(mp) - 1);

	kmem_free(tmpbuffer, XFS_LBSIZE(mp));
}

/*
 * Redistribute the attribute list entries between two leaf nodes,
 * taking into account the size of the new entry.
 *
 * NOTE: if new block is empty, then it will get the upper half of the
 * old block.  At present, all (one) callers pass in an empty second block.
 *
 * This code adjusts the args->index/blkno and args->index2/blkno2 fields
 * to match what it is doing in splitting the attribute leaf block.  Those
 * values are used in "atomic rename" operations on attributes.  Note that
 * the "new" and "old" values can end up in different blocks.
 */
STATIC void
xfs_attr_leaf_rebalance(xfs_da_state_t *state, xfs_da_state_blk_t *blk1,
				       xfs_da_state_blk_t *blk2)
{
	xfs_da_args_t *args;
	xfs_da_state_blk_t *tmp_blk;
	xfs_attr_leafblock_t *leaf1, *leaf2;
	xfs_attr_leaf_hdr_t *hdr1, *hdr2;
	int count, totallen, max, space, swap;

	/*
	 * Set up environment.
	 */
	ASSERT(blk1->magic == XFS_ATTR_LEAF_MAGIC);
	ASSERT(blk2->magic == XFS_ATTR_LEAF_MAGIC);
	leaf1 = blk1->bp->data;
	leaf2 = blk2->bp->data;
	ASSERT(be16_to_cpu(leaf1->hdr.info.magic) == XFS_ATTR_LEAF_MAGIC);
	ASSERT(be16_to_cpu(leaf2->hdr.info.magic) == XFS_ATTR_LEAF_MAGIC);
	args = state->args;

	/*
	 * Check ordering of blocks, reverse if it makes things simpler.
	 *
	 * NOTE: Given that all (current) callers pass in an empty
	 * second block, this code should never set "swap".
	 */
	swap = 0;
	if (xfs_attr_leaf_order(blk1->bp, blk2->bp)) {
		tmp_blk = blk1;
		blk1 = blk2;
		blk2 = tmp_blk;
		leaf1 = blk1->bp->data;
		leaf2 = blk2->bp->data;
		swap = 1;
	}
	hdr1 = &leaf1->hdr;
	hdr2 = &leaf2->hdr;