xfs_alloc.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 2,225 行 · 第 1/5 页

	 * In the first case above, we got the last entry in the
	 * by-size btree.  Now we check to see if the space hits maxlen
	 * once aligned; if not, we search left for something better.
	 * This can't happen in the second case above.
	 */
	xfs_alloc_compute_aligned(fbno, flen, args->alignment, args->minlen,
		&rbno, &rlen);
	rlen = XFS_EXTLEN_MIN(args->maxlen, rlen);
	XFS_WANT_CORRUPTED_GOTO(rlen == 0 ||
			(rlen <= flen && rbno + rlen <= fbno + flen), error0);
	if (rlen < args->maxlen) {
		xfs_agblock_t	bestfbno;
		xfs_extlen_t	bestflen;
		xfs_agblock_t	bestrbno;
		xfs_extlen_t	bestrlen;

		bestrlen = rlen;
		bestrbno = rbno;
		bestflen = flen;
		bestfbno = fbno;
		for (;;) {
			if ((error = xfs_alloc_decrement(cnt_cur, 0, &i)))
				goto error0;
			if (i == 0)
				break;
			if ((error = xfs_alloc_get_rec(cnt_cur, &fbno, &flen,
					&i)))
				goto error0;
			XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
			if (flen < bestrlen)
				break;
			xfs_alloc_compute_aligned(fbno, flen, args->alignment,
				args->minlen, &rbno, &rlen);
			rlen = XFS_EXTLEN_MIN(args->maxlen, rlen);
			XFS_WANT_CORRUPTED_GOTO(rlen == 0 ||
				(rlen <= flen && rbno + rlen <= fbno + flen),
				error0);
			if (rlen > bestrlen) {
				bestrlen = rlen;
				bestrbno = rbno;
				bestflen = flen;
				bestfbno = fbno;
				if (rlen == args->maxlen)
					break;
			}
		}
		if ((error = xfs_alloc_lookup_eq(cnt_cur, bestfbno, bestflen,
				&i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
		rlen = bestrlen;
		rbno = bestrbno;
		flen = bestflen;
		fbno = bestfbno;
	}
	args->wasfromfl = 0;
	/*
	 * Fix up the length.
	 */
	args->len = rlen;
	xfs_alloc_fix_len(args);
	if (rlen < args->minlen || !xfs_alloc_fix_minleft(args)) {
		xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
		TRACE_ALLOC("nominleft", args);
		args->agbno = NULLAGBLOCK;
		return 0;
	}
	rlen = args->len;
	XFS_WANT_CORRUPTED_GOTO(rlen <= flen, error0);
	/*
	 * Allocate and initialize a cursor for the by-block tree.
	 */
	bno_cur = xfs_btree_init_cursor(args->mp, args->tp, args->agbp,
		args->agno, XFS_BTNUM_BNO, NULL, 0);
	if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur, fbno, flen,
			rbno, rlen, XFSA_FIXUP_CNT_OK)))
		goto error0;
	xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
	xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
	cnt_cur = bno_cur = NULL;
	args->len = rlen;
	args->agbno = rbno;
	XFS_WANT_CORRUPTED_GOTO(
		args->agbno + args->len <=
			INT_GET(XFS_BUF_TO_AGF(args->agbp)->agf_length,
			ARCH_CONVERT),
		error0);
	TRACE_ALLOC("normal", args);
	return 0;

error0:
	TRACE_ALLOC("error", args);
	if (cnt_cur)
		xfs_btree_del_cursor(cnt_cur, XFS_BTREE_ERROR);
	if (bno_cur)
		xfs_btree_del_cursor(bno_cur, XFS_BTREE_ERROR);
	return error;
}

/*
 * Deal with the case where only small freespaces remain.
 * Either return the contents of the last freespace record,
 * or allocate space from the freelist if there is nothing in the tree.
 */
STATIC int			/* error */
xfs_alloc_ag_vextent_small(
	xfs_alloc_arg_t	*args,	/* allocation argument structure */
	xfs_btree_cur_t	*ccur,	/* by-size cursor */
	xfs_agblock_t	*fbnop,	/* result block number */
	xfs_extlen_t	*flenp,	/* result length */
	int		*stat)	/* status: 0-freelist, 1-normal/none */
{
	int		error;
	xfs_agblock_t	fbno;
	xfs_extlen_t	flen;
#ifdef XFS_ALLOC_TRACE
	static char	fname[] = "xfs_alloc_ag_vextent_small";
#endif
	int		i;

	if ((error = xfs_alloc_decrement(ccur, 0, &i)))
		goto error0;
	if (i) {
		if ((error = xfs_alloc_get_rec(ccur, &fbno, &flen, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
	}
	/*
	 * Nothing in the btree, try the freelist.  Make sure
	 * to respect minleft even when pulling from the
	 * freelist.
	 */
	else if (args->minlen == 1 && args->alignment == 1 && !args->isfl &&
		 (INT_GET(XFS_BUF_TO_AGF(args->agbp)->agf_flcount,
			ARCH_CONVERT) > args->minleft)) {
		if ((error = xfs_alloc_get_freelist(args->tp, args->agbp, &fbno)))
			goto error0;
		if (fbno != NULLAGBLOCK) {
			if (args->userdata) {
				xfs_buf_t	*bp;

				bp = xfs_btree_get_bufs(args->mp, args->tp,
					args->agno, fbno, 0);
				xfs_trans_binval(args->tp, bp);
			}
			args->len = 1;
			args->agbno = fbno;
			XFS_WANT_CORRUPTED_GOTO(
				args->agbno + args->len <=
				INT_GET(XFS_BUF_TO_AGF(args->agbp)->agf_length,
					ARCH_CONVERT),
				error0);
			args->wasfromfl = 1;
			TRACE_ALLOC("freelist", args);
			*stat = 0;
			return 0;
		}
		/*
		 * Nothing in the freelist.
		 */
		else
			flen = 0;
	}
	/*
	 * Can't allocate from the freelist for some reason.
	 */
	else
		flen = 0;
	/*
	 * Can't do the allocation, give up.
	 */
	if (flen < args->minlen) {
		args->agbno = NULLAGBLOCK;
		TRACE_ALLOC("notenough", args);
		flen = 0;
	}
	*fbnop = fbno;
	*flenp = flen;
	*stat = 1;
	TRACE_ALLOC("normal", args);
	return 0;

error0:
	TRACE_ALLOC("error", args);
	return error;
}

/*
 * Free the extent starting at agno/bno for length.
 */
STATIC int			/* error */
xfs_free_ag_extent(
	xfs_trans_t	*tp,	/* transaction pointer */
	xfs_buf_t	*agbp,	/* buffer for a.g. freelist header */
	xfs_agnumber_t	agno,	/* allocation group number */
	xfs_agblock_t	bno,	/* starting block number */
	xfs_extlen_t	len,	/* length of extent */
	int		isfl)	/* set if is freelist blocks - no sb acctg */
{
	xfs_btree_cur_t	*bno_cur;	/* cursor for by-block btree */
	xfs_btree_cur_t	*cnt_cur;	/* cursor for by-size btree */
	int		error;		/* error return value */
#ifdef XFS_ALLOC_TRACE
	static char	fname[] = "xfs_free_ag_extent";
#endif
	xfs_agblock_t	gtbno;		/* start of right neighbor block */
	xfs_extlen_t	gtlen;		/* length of right neighbor block */
	int		haveleft;	/* have a left neighbor block */
	int		haveright;	/* have a right neighbor block */
	int		i;		/* temp, result code */
	xfs_agblock_t	ltbno;		/* start of left neighbor block */
	xfs_extlen_t	ltlen;		/* length of left neighbor block */
	xfs_mount_t	*mp;		/* mount point struct for filesystem */
	xfs_agblock_t	nbno;		/* new starting block of freespace */
	xfs_extlen_t	nlen;		/* new length of freespace */

	mp = tp->t_mountp;
	/*
	 * Allocate and initialize a cursor for the by-block btree.
	 */
	bno_cur = xfs_btree_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_BNO, NULL,
		0);
	cnt_cur = NULL;
	/*
	 * Look for a neighboring block on the left (lower block numbers)
	 * that is contiguous with this space.
	 */
	if ((error = xfs_alloc_lookup_le(bno_cur, bno, len, &haveleft)))
		goto error0;
	if (haveleft) {
		/*
		 * There is a block to our left.
		 */
		if ((error = xfs_alloc_get_rec(bno_cur, &ltbno, &ltlen, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
		/*
		 * It's not contiguous, though.
		 */
		if (ltbno + ltlen < bno)
			haveleft = 0;
		else {
			/*
			 * If this failure happens the request to free this
			 * space was invalid, it's (partly) already free.
			 * Very bad.
			 */
			XFS_WANT_CORRUPTED_GOTO(ltbno + ltlen <= bno, error0);
		}
	}
	/*
	 * Look for a neighboring block on the right (higher block numbers)
	 * that is contiguous with this space.
	 */
	if ((error = xfs_alloc_increment(bno_cur, 0, &haveright)))
		goto error0;
	if (haveright) {
		/*
		 * There is a block to our right.
		 */
		if ((error = xfs_alloc_get_rec(bno_cur, &gtbno, &gtlen, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
		/*
		 * It's not contiguous, though.
		 */
		if (bno + len < gtbno)
			haveright = 0;
		else {
			/*
			 * If this failure happens the request to free this
			 * space was invalid, it's (partly) already free.
			 * Very bad.
			 */
			XFS_WANT_CORRUPTED_GOTO(gtbno >= bno + len, error0);
		}
	}
	/*
	 * Now allocate and initialize a cursor for the by-size tree.
	 */
	cnt_cur = xfs_btree_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_CNT, NULL,
		0);
	/*
	 * Have both left and right contiguous neighbors.
	 * Merge all three into a single free block.
	 */
	if (haveleft && haveright) {
		/*
		 * Delete the old by-size entry on the left.
		 */
		if ((error = xfs_alloc_lookup_eq(cnt_cur, ltbno, ltlen, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
		if ((error = xfs_alloc_delete(cnt_cur, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
		/*
		 * Delete the old by-size entry on the right.
		 */
		if ((error = xfs_alloc_lookup_eq(cnt_cur, gtbno, gtlen, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
		if ((error = xfs_alloc_delete(cnt_cur, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
		/*
		 * Delete the old by-block entry for the right block.
		 */
		if ((error = xfs_alloc_delete(bno_cur, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
		/*
		 * Move the by-block cursor back to the left neighbor.
		 */
		if ((error = xfs_alloc_decrement(bno_cur, 0, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
#ifdef DEBUG
		/*
		 * Check that this is the right record: delete didn't
		 * mangle the cursor.
		 */
		{
			xfs_agblock_t	xxbno;
			xfs_extlen_t	xxlen;

			if ((error = xfs_alloc_get_rec(bno_cur, &xxbno, &xxlen,
					&i)))
				goto error0;
			XFS_WANT_CORRUPTED_GOTO(
				i == 1 && xxbno == ltbno && xxlen == ltlen,
				error0);
		}
#endif
		/*
		 * Update remaining by-block entry to the new, joined block.
		 */
		nbno = ltbno;
		nlen = len + ltlen + gtlen;
		if ((error = xfs_alloc_update(bno_cur, nbno, nlen)))
			goto error0;
	}
	/*
	 * Have only a left contiguous neighbor.
	 * Merge it together with the new freespace.
	 */
	else if (haveleft) {
		/*
		 * Delete the old by-size entry on the left.
		 */
		if ((error = xfs_alloc_lookup_eq(cnt_cur, ltbno, ltlen, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
		if ((error = xfs_alloc_delete(cnt_cur, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
		/*
		 * Back up the by-block cursor to the left neighbor, and
		 * update its length.
		 */
		if ((error = xfs_alloc_decrement(bno_cur, 0, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
		nbno = ltbno;
		nlen = len + ltlen;
		if ((error = xfs_alloc_update(bno_cur, nbno, nlen)))
			goto error0;
	}
	/*
	 * Have only a right contiguous neighbor.
	 * Merge it together with the new freespace.
	 */
	else if (haveright) {
		/*
		 * Delete the old by-size entry on the right.
		 */
		if ((error = xfs_alloc_lookup_eq(cnt_cur, gtbno, gtlen, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
		if ((error = xfs_alloc_delete(cnt_cur, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
		/*
		 * Update the starting block and length of the right
		 * neighbor in the by-block tree.
		 */
		nbno = bno;
		nlen = len + gtlen;
		if ((error = xfs_alloc_update(bno_cur, nbno, nlen)))
			goto error0;
	}
	/*
	 * No contiguous neighbors.
	 * Insert the new freespace into the by-block tree.
	 */
	else {
		nbno = bno;
		nlen = len;
		if ((error = xfs_alloc_insert(bno_cur, &i)))
			goto error0;
		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
	}
	xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
	bno_cur = NULL;
	/*
	 * In all cases we need to insert the new freespace in the by-size tree.
	 */
	if ((error = xfs_alloc_lookup_eq(cnt_cur, nbno, nlen, &i)))
		goto error0;
	XFS_WANT_CORRUPTED_GOTO(i == 0, error0);
	if ((error = xfs_alloc_insert(cnt_cur, &i)))
		goto error0;
	XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
	xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
	cnt_cur = NULL;
	/*
	 * Update the freespace totals in the ag and superblock.
	 */
	{
		xfs_agf_t	*agf;
		xfs_perag_t	*pag;		/* per allocation group data */

		agf = XFS_BUF_TO_AGF(agbp);
		pag = &mp->m_perag[agno];
		INT_MOD(agf->agf_freeblks, ARCH_CONVERT, len);
		xfs_trans_agblocks_delta(tp, len);
		pag->pagf_freeblks += len;
		XFS_WANT_CORRUPTED_GOTO(
			INT_GET(agf->agf_freeblks, ARCH_CONVERT)
				<= INT_GET(agf->agf_length, ARCH_CONVERT),
			error0);
		TRACE_MODAGF(NULL, agf, XFS_AGF_FREEBLKS);
		xfs_alloc_log_agf(tp, agbp, XFS_AGF_FREEBLKS);
		if (!isfl)
			xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, (long)len);
		XFS_STATS_INC(xs_freex);
		XFS_STATS_ADD(xs_freeb, len);
	}
	TRACE_FREE(haveleft ?
			(haveright ? "both" : "left") :
			(haveright ? "right" : "none"),
		agno, bno, len, isfl);

	/*
	 * Since blocks move to the free list without the coordination