xfs_ialloc_btree.c

linux 内核源代码

/*
 * Insert one record/level.  Return information to the caller
 * allowing the next level up to proceed if necessary.
 */
STATIC int				/* error */
xfs_inobt_insrec(
	xfs_btree_cur_t		*cur,	/* btree cursor */
	int			level,	/* level to insert record at */
	xfs_agblock_t		*bnop,	/* i/o: block number inserted */
	xfs_inobt_rec_t		*recp,	/* i/o: record data inserted */
	xfs_btree_cur_t		**curp,	/* output: new cursor replacing cur */
	int			*stat)	/* success/failure */
{
	xfs_inobt_block_t	*block;	/* btree block record/key lives in */
	xfs_buf_t		*bp;	/* buffer for block */
	int			error;	/* error return value */
	int			i;	/* loop index */
	xfs_inobt_key_t		key;	/* key value being inserted */
	xfs_inobt_key_t		*kp=NULL;	/* pointer to btree keys */
	xfs_agblock_t		nbno;	/* block number of allocated block */
	xfs_btree_cur_t		*ncur;	/* new cursor to be used at next lvl */
	xfs_inobt_key_t		nkey;	/* new key value, from split */
	xfs_inobt_rec_t		nrec;	/* new record value, for caller */
	int			numrecs;
	int			optr;	/* old ptr value */
	xfs_inobt_ptr_t		*pp;	/* pointer to btree addresses */
	int			ptr;	/* index in btree block for this rec */
	xfs_inobt_rec_t		*rp=NULL;	/* pointer to btree records */

	/*
	 * GCC doesn't understand the (arguably complex) control flow in
	 * this function and complains about uninitialized structure fields
	 * without this.
	 */
	memset(&nrec, 0, sizeof(nrec));

	/*
	 * If we made it to the root level, allocate a new root block
	 * and we're done.
	 */
	if (level >= cur->bc_nlevels) {
		error = xfs_inobt_newroot(cur, &i);
		*bnop = NULLAGBLOCK;
		*stat = i;
		return error;
	}
	/*
	 * Make a key out of the record data to be inserted, and save it.
	 */
	key.ir_startino = recp->ir_startino;
	optr = ptr = cur->bc_ptrs[level];
	/*
	 * If we're off the left edge, return failure.
	 */
	if (ptr == 0) {
		*stat = 0;
		return 0;
	}
	/*
	 * Get pointers to the btree buffer and block.
	 */
	bp = cur->bc_bufs[level];
	block = XFS_BUF_TO_INOBT_BLOCK(bp);
	numrecs = be16_to_cpu(block->bb_numrecs);
#ifdef DEBUG
	if ((error = xfs_btree_check_sblock(cur, block, level, bp)))
		return error;
	/*
	 * Check that the new entry is being inserted in the right place.
	 */
	if (ptr <= numrecs) {
		if (level == 0) {
			rp = XFS_INOBT_REC_ADDR(block, ptr, cur);
			xfs_btree_check_rec(cur->bc_btnum, recp, rp);
		} else {
			kp = XFS_INOBT_KEY_ADDR(block, ptr, cur);
			xfs_btree_check_key(cur->bc_btnum, &key, kp);
		}
	}
#endif
	nbno = NULLAGBLOCK;
	ncur = NULL;
	/*
	 * If the block is full, we can't insert the new entry until we
	 * make the block un-full.
	 */
	if (numrecs == XFS_INOBT_BLOCK_MAXRECS(level, cur)) {
		/*
		 * First, try shifting an entry to the right neighbor.
		 */
		if ((error = xfs_inobt_rshift(cur, level, &i)))
			return error;
		if (i) {
			/* nothing */
		}
		/*
		 * Next, try shifting an entry to the left neighbor.
		 */
		else {
			if ((error = xfs_inobt_lshift(cur, level, &i)))
				return error;
			if (i) {
				optr = ptr = cur->bc_ptrs[level];
			} else {
				/*
				 * Next, try splitting the current block
				 * in half. If this works we have to
				 * re-set our variables because
				 * we could be in a different block now.
				 */
				if ((error = xfs_inobt_split(cur, level, &nbno,
						&nkey, &ncur, &i)))
					return error;
				if (i) {
					bp = cur->bc_bufs[level];
					block = XFS_BUF_TO_INOBT_BLOCK(bp);
#ifdef DEBUG
					if ((error = xfs_btree_check_sblock(cur,
							block, level, bp)))
						return error;
#endif
					ptr = cur->bc_ptrs[level];
					nrec.ir_startino = nkey.ir_startino;
				} else {
					/*
					 * Otherwise the insert fails.
					 */
					*stat = 0;
					return 0;
				}
			}
		}
	}
	/*
	 * At this point we know there's room for our new entry in the block
	 * we're pointing at.
	 */
	numrecs = be16_to_cpu(block->bb_numrecs);
	if (level > 0) {
		/*
		 * It's a non-leaf entry.  Make a hole for the new data
		 * in the key and ptr regions of the block.
		 */
		kp = XFS_INOBT_KEY_ADDR(block, 1, cur);
		pp = XFS_INOBT_PTR_ADDR(block, 1, cur);
#ifdef DEBUG
		for (i = numrecs; i >= ptr; i--) {
			if ((error = xfs_btree_check_sptr(cur, be32_to_cpu(pp[i - 1]), level)))
				return error;
		}
#endif
		memmove(&kp[ptr], &kp[ptr - 1],
			(numrecs - ptr + 1) * sizeof(*kp));
		memmove(&pp[ptr], &pp[ptr - 1],
			(numrecs - ptr + 1) * sizeof(*pp));
		/*
		 * Now stuff the new data in, bump numrecs and log the new data.
		 */
#ifdef DEBUG
		if ((error = xfs_btree_check_sptr(cur, *bnop, level)))
			return error;
#endif
		kp[ptr - 1] = key;
		pp[ptr - 1] = cpu_to_be32(*bnop);
		numrecs++;
		block->bb_numrecs = cpu_to_be16(numrecs);
		xfs_inobt_log_keys(cur, bp, ptr, numrecs);
		xfs_inobt_log_ptrs(cur, bp, ptr, numrecs);
	} else {
		/*
		 * It's a leaf entry.  Make a hole for the new record.
		 */
		rp = XFS_INOBT_REC_ADDR(block, 1, cur);
		memmove(&rp[ptr], &rp[ptr - 1],
			(numrecs - ptr + 1) * sizeof(*rp));
		/*
		 * Now stuff the new record in, bump numrecs
		 * and log the new data.
		 */
		rp[ptr - 1] = *recp;
		numrecs++;
		block->bb_numrecs = cpu_to_be16(numrecs);
		xfs_inobt_log_recs(cur, bp, ptr, numrecs);
	}
	/*
	 * Log the new number of records in the btree header.
	 */
	xfs_inobt_log_block(cur->bc_tp, bp, XFS_BB_NUMRECS);
#ifdef DEBUG
	/*
	 * Check that the key/record is in the right place, now.
	 */
	if (ptr < numrecs) {
		if (level == 0)
			xfs_btree_check_rec(cur->bc_btnum, rp + ptr - 1,
				rp + ptr);
		else
			xfs_btree_check_key(cur->bc_btnum, kp + ptr - 1,
				kp + ptr);
	}
#endif
	/*
	 * If we inserted at the start of a block, update the parents' keys.
	 */
	if (optr == 1 && (error = xfs_inobt_updkey(cur, &key, level + 1)))
		return error;
	/*
	 * Return the new block number, if any.
	 * If there is one, give back a record value and a cursor too.
	 */
	*bnop = nbno;
	if (nbno != NULLAGBLOCK) {
		*recp = nrec;
		*curp = ncur;
	}
	*stat = 1;
	return 0;
}

/*
 * Log header fields from a btree block.
 */
STATIC void
xfs_inobt_log_block(
	xfs_trans_t		*tp,	/* transaction pointer */
	xfs_buf_t		*bp,	/* buffer containing btree block */
	int			fields)	/* mask of fields: XFS_BB_... */
{
	int			first;	/* first byte offset logged */
	int			last;	/* last byte offset logged */
	static const short	offsets[] = {	/* table of offsets */
		offsetof(xfs_inobt_block_t, bb_magic),
		offsetof(xfs_inobt_block_t, bb_level),
		offsetof(xfs_inobt_block_t, bb_numrecs),
		offsetof(xfs_inobt_block_t, bb_leftsib),
		offsetof(xfs_inobt_block_t, bb_rightsib),
		sizeof(xfs_inobt_block_t)
	};

	xfs_btree_offsets(fields, offsets, XFS_BB_NUM_BITS, &first, &last);
	xfs_trans_log_buf(tp, bp, first, last);
}

/*
 * Log keys from a btree block (nonleaf).
 */
STATIC void
xfs_inobt_log_keys(
	xfs_btree_cur_t		*cur,	/* btree cursor */
	xfs_buf_t		*bp,	/* buffer containing btree block */
	int			kfirst,	/* index of first key to log */
	int			klast)	/* index of last key to log */
{
	xfs_inobt_block_t	*block;	/* btree block to log from */
	int			first;	/* first byte offset logged */
	xfs_inobt_key_t		*kp;	/* key pointer in btree block */
	int			last;	/* last byte offset logged */

	block = XFS_BUF_TO_INOBT_BLOCK(bp);
	kp = XFS_INOBT_KEY_ADDR(block, 1, cur);
	first = (int)((xfs_caddr_t)&kp[kfirst - 1] - (xfs_caddr_t)block);
	last = (int)(((xfs_caddr_t)&kp[klast] - 1) - (xfs_caddr_t)block);
	xfs_trans_log_buf(cur->bc_tp, bp, first, last);
}

/*
 * Log block pointer fields from a btree block (nonleaf).
 */
STATIC void
xfs_inobt_log_ptrs(
	xfs_btree_cur_t		*cur,	/* btree cursor */
	xfs_buf_t		*bp,	/* buffer containing btree block */
	int			pfirst,	/* index of first pointer to log */
	int			plast)	/* index of last pointer to log */
{
	xfs_inobt_block_t	*block;	/* btree block to log from */
	int			first;	/* first byte offset logged */
	int			last;	/* last byte offset logged */
	xfs_inobt_ptr_t		*pp;	/* block-pointer pointer in btree blk */

	block = XFS_BUF_TO_INOBT_BLOCK(bp);
	pp = XFS_INOBT_PTR_ADDR(block, 1, cur);
	first = (int)((xfs_caddr_t)&pp[pfirst - 1] - (xfs_caddr_t)block);
	last = (int)(((xfs_caddr_t)&pp[plast] - 1) - (xfs_caddr_t)block);
	xfs_trans_log_buf(cur->bc_tp, bp, first, last);
}

/*
 * Log records from a btree block (leaf).
 */
STATIC void
xfs_inobt_log_recs(
	xfs_btree_cur_t		*cur,	/* btree cursor */
	xfs_buf_t		*bp,	/* buffer containing btree block */
	int			rfirst,	/* index of first record to log */
	int			rlast)	/* index of last record to log */
{
	xfs_inobt_block_t	*block;	/* btree block to log from */
	int			first;	/* first byte offset logged */
	int			last;	/* last byte offset logged */
	xfs_inobt_rec_t		*rp;	/* record pointer for btree block */

	block = XFS_BUF_TO_INOBT_BLOCK(bp);
	rp = XFS_INOBT_REC_ADDR(block, 1, cur);
	first = (int)((xfs_caddr_t)&rp[rfirst - 1] - (xfs_caddr_t)block);
	last = (int)(((xfs_caddr_t)&rp[rlast] - 1) - (xfs_caddr_t)block);
	xfs_trans_log_buf(cur->bc_tp, bp, first, last);
}

/*
 * Lookup the record.  The cursor is made to point to it, based on dir.
 * Return 0 if can't find any such record, 1 for success.
 */
STATIC int				/* error */
xfs_inobt_lookup(
	xfs_btree_cur_t		*cur,	/* btree cursor */
	xfs_lookup_t		dir,	/* <=, ==, or >= */
	int			*stat)	/* success/failure */
{
	xfs_agblock_t		agbno;	/* a.g. relative btree block number */
	xfs_agnumber_t		agno;	/* allocation group number */
	xfs_inobt_block_t	*block=NULL;	/* current btree block */
	__int64_t		diff;	/* difference for the current key */
	int			error;	/* error return value */
	int			keyno=0;	/* current key number */
	int			level;	/* level in the btree */
	xfs_mount_t		*mp;	/* file system mount point */

	/*
	 * Get the allocation group header, and the root block number.
	 */
	mp = cur->bc_mp;
	{
		xfs_agi_t	*agi;	/* a.g. inode header */

		agi = XFS_BUF_TO_AGI(cur->bc_private.i.agbp);
		agno = be32_to_cpu(agi->agi_seqno);
		agbno = be32_to_cpu(agi->agi_root);
	}
	/*
	 * Iterate over each level in the btree, starting at the root.
	 * For each level above the leaves, find the key we need, based
	 * on the lookup record, then follow the corresponding block
	 * pointer down to the next level.
	 */
	for (level = cur->bc_nlevels - 1, diff = 1; level >= 0; level--) {
		xfs_buf_t	*bp;	/* buffer pointer for btree block */
		xfs_daddr_t	d;	/* disk address of btree block */

		/*
		 * Get the disk address we're looking for.
		 */
		d = XFS_AGB_TO_DADDR(mp, agno, agbno);
		/*
		 * If the old buffer at this level is for a different block,
		 * throw it away, otherwise just use it.
		 */
		bp = cur->bc_bufs[level];
		if (bp && XFS_BUF_ADDR(bp) != d)
			bp = NULL;
		if (!bp) {
			/*
			 * Need to get a new buffer.  Read it, then
			 * set it in the cursor, releasing the old one.
			 */
			if ((error = xfs_btree_read_bufs(mp, cur->bc_tp,
					agno, agbno, 0, &bp, XFS_INO_BTREE_REF)))
				return error;
			xfs_btree_setbuf(cur, level, bp);
			/*
			 * Point to the btree block, now that we have the buffer
			 */
			block = XFS_BUF_TO_INOBT_BLOCK(bp);
			if ((error = xfs_btree_check_sblock(cur, block, level,
					bp)))
				return error;
		} else
			block = XFS_BUF_TO_INOBT_BLOCK(bp);
		/*
		 * If we already had a key match at a higher level, we know
		 * we need to use the first entry in this block.
		 */
		if (diff == 0)
			keyno = 1;
		/*
		 * Otherwise we need to search this block.  Do a binary search.
		 */
		else {
			int		high;	/* high entry number */
			xfs_inobt_key_t	*kkbase=NULL;/* base of keys in block */
			xfs_inobt_rec_t	*krbase=NULL;/* base of records in block */
			int		low;	/* low entry number */

			/*
			 * Get a pointer to keys or records.
			 */
			if (level > 0)
				kkbase = XFS_INOBT_KEY_ADDR(block, 1, cur);
			else
				krbase = XFS_INOBT_REC_ADDR(block, 1, cur);
			/*
			 * Set low and high entry numbers, 1-based.
			 */
			low = 1;
			if (!(high = be16_to_cpu(block->bb_numrecs))) {
				/*
				 * If the block is empty, the tree must
				 * be an empty leaf.
				 */
				ASSERT(level == 0 && cur->bc_nlevels == 1);
				cur->bc_ptrs[0] = dir != XFS_LOOKUP_LE;
				*stat = 0;
				return 0;
			}
			/*
			 * Binary search the block.
			 */
			while (low <= high) {
				xfs_agino_t	startino;	/* key value */

				/*
				 * keyno is average of low and high.
				 */
				keyno = (low + high) >> 1;
				/*
				 * Get startino.
				 */
				if (level > 0) {
					xfs_inobt_key_t	*kkp;

					kkp = kkbase + keyno - 1;
					startino = be32_to_cpu(kkp->ir_startino);
				} else {
					xfs_inobt_rec_t	*krp;

					krp = krbase + keyno - 1;
					startino = be32_to_cpu(krp->ir_startino);
				}
				/*
				 * Compute difference to get next direction.
				 */
				diff = (__int64_t)
					startino - cur->bc_rec.i.ir_startino;
				/*
				 * Less than, move right.
				 */
				if (diff < 0)
					low = keyno + 1;
				/*
				 * Greater than, move left.
				 */
				else if (diff > 0)
					high = keyno - 1;
				/*
				 * Equal, we're done.
				 */
				else
					break;
			}
		}
		/*
		 * If there are more levels, set up for the next level
		 * by getting the block number and filling in the cursor.
		 */
		if (level > 0) {
			/*
			 * If we moved left, need the previous key number,
			 * unless there isn't one.
			 */
			if (diff > 0 && --keyno < 1)
				keyno = 1;
			agbno = be32_to_cpu(*XFS_INOBT_PTR_ADDR(block, keyno, cur));
#ifdef DEBUG
			if ((error = xfs_btree_check_sptr(cur, agbno, level)))
				return error;
#endif
			cur->bc_ptrs[level] = keyno;
		}
	}
	/*
	 * Done with the search.
	 * See if we need to adjust the results.
	 */
	if (dir != XFS_LOOKUP_LE && diff < 0) {
		keyno++;
		/*
		 * If ge search and we went off the end of the block, but it's
		 * not the last block, we're in the wrong block.
		 */
		if (dir == XFS_LOOKUP_GE &&
		    keyno > be16_to_cpu(block->bb_numrecs) &&
		    be32_to_cpu(block->bb_rightsib) != NULLAGBLOCK) {
			int	i;

			cur->bc_ptrs[0] = keyno;
			if ((error = xfs_inobt_increment(cur, 0, &i)))
				return error;
			ASSERT(i == 1);
			*stat = 1;
			return 0;
		}
	}
	else if (dir == XFS_LOOKUP_LE && diff > 0)
		keyno--;
	cur->bc_ptrs[0] = keyno;
	/*
	 * Return if we succeeded or not.
	 */
	if (keyno == 0 || keyno > be16_to_cpu(block->bb_numrecs))
		*stat = 0;
	else
		*stat = ((dir != XFS_LOOKUP_EQ) || (diff == 0));
	return 0;
}

/*
 * Move 1 record left from cur/level if possible.
 * Update cur to reflect the new path.
 */