subr_extent.c

基于组件方式开发操作系统的OSKIT源代码

/*	$NetBSD: subr_extent.c,v 1.39 2000/12/06 18:05:57 thorpej Exp $	*/

/*-
 * Copyright (c) 1996, 1998 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe and Matthias Drochner.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the NetBSD
 *	Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * General purpose extent manager.
 */

#ifdef _KERNEL
#include <sys/param.h>
#include <sys/extent.h>
#include <sys/malloc.h>
#include <sys/pool.h>
#include <sys/time.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/lock.h>

#include <uvm/uvm_extern.h>

#define	KMEM_IS_RUNNING		(kmem_map != NULL)
#elif defined(_EXTENT_TESTING)
/*
 * user-land definitions, so it can fit into a testing harness.
 */
#include <sys/param.h>
#include <sys/pool.h>
#include <sys/extent.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

/*
 * Use multi-line #defines to avoid screwing up the kernel tags file;
 * without this, ctags produces a tags file where panic() shows up
 * in subr_extent.c rather than subr_prf.c.
 */
#define	\
malloc(s, t, flags)		malloc(s)
#define	\
free(p, t)			free(p)
#define	\
tsleep(chan, pri, str, timo)	(EWOULDBLOCK)
#define	\
ltsleep(chan,pri,str,timo,lck)	(EWOULDBLOCK)
#define	\
wakeup(chan)			((void)0)
#define	\
pool_get(pool, flags)		malloc(pool->pr_size,0,0)
#define	\
pool_put(pool, rp)		free(rp,0)
#define	\
panic(a)			printf(a)
#define	\
splhigh()			(1)
#define	\
splx(s)				((void)(s))

#define	\
simple_lock_init(l)		((void)(l))
#define	\
simple_lock(l)			((void)(l))
#define	\
simple_unlock(l)		((void)(l))
#define	KMEM_IS_RUNNING			(1)
#endif

static	struct pool *expool_create __P((void));
static	void extent_insert_and_optimize __P((struct extent *, u_long, u_long,
	    int, struct extent_region *, struct extent_region *));
static	struct extent_region *extent_alloc_region_descriptor
	    __P((struct extent *, int));
static	void extent_free_region_descriptor __P((struct extent *,
	    struct extent_region *));

static struct pool *expool;

/*
 * Macro to align to an arbitrary power-of-two boundary.
 */
#define EXTENT_ALIGN(_start, _align, _skew)		\
	(((((_start) - (_skew)) + ((_align) - 1)) & (-(_align))) + (_skew))

/*
 * Create the extent_region pool.
 * (This is deferred until one of our callers thinks we can malloc()).
 */

static struct pool *expool_create()
{
#if defined(_KERNEL)
	expool = pool_create(sizeof(struct extent_region), 0, 0,
			     0, "extent", 0, 0, 0, 0);
#else
	expool = (struct pool *)malloc(sizeof(*expool),0,0);
	expool->pr_size = sizeof(struct extent_region);
#endif
	return (expool);
}

/*
 * Allocate and initialize an extent map.
 */
struct extent *
extent_create(name, start, end, mtype, storage, storagesize, flags)
	const char *name;
	u_long start, end;
	int mtype;
	caddr_t storage;
	size_t storagesize;
	int flags;
{
	struct extent *ex;
	caddr_t cp = storage;
	size_t sz = storagesize;
	struct extent_region *rp;
	int fixed_extent = (storage != NULL);
	int s;

#ifdef DIAGNOSTIC
	/* Check arguments. */
	if (name == NULL)
		panic("extent_create: name == NULL");
	if (end < start) {
		printf("extent_create: extent `%s', start 0x%lx, end 0x%lx\n",
		    name, start, end);
		panic("extent_create: end < start");
	}
	if (fixed_extent && (storagesize < sizeof(struct extent_fixed)))
		panic("extent_create: fixed extent, bad storagesize 0x%lx",
		    (u_long)storagesize);
	if (fixed_extent == 0 && (storagesize != 0 || storage != NULL))
		panic("extent_create: storage provided for non-fixed");
#endif

	/* Allocate extent descriptor. */
	if (fixed_extent) {
		struct extent_fixed *fex;

		memset(storage, 0, storagesize);

		/*
		 * Align all descriptors on "long" boundaries.
		 */
		fex = (struct extent_fixed *)cp;
		ex = (struct extent *)fex;
		cp += ALIGN(sizeof(struct extent_fixed));
		sz -= ALIGN(sizeof(struct extent_fixed));
		fex->fex_storage = storage;
		fex->fex_storagesize = storagesize;

		/*
		 * In a fixed extent, we have to pre-allocate region
		 * descriptors and place them in the extent's freelist.
		 */
		LIST_INIT(&fex->fex_freelist);
		while (sz >= ALIGN(sizeof(struct extent_region))) {
			rp = (struct extent_region *)cp;
			cp += ALIGN(sizeof(struct extent_region));
			sz -= ALIGN(sizeof(struct extent_region));
			LIST_INSERT_HEAD(&fex->fex_freelist, rp, er_link);
		}
	} else {
		s = splhigh();
		if (expool == NULL)
			expool_create();
		splx(s);
		if (expool == NULL)
			return (NULL);

		ex = (struct extent *)malloc(sizeof(struct extent),
		    mtype, (flags & EX_WAITOK) ? M_WAITOK : M_NOWAIT);
		if (ex == NULL)
			return (NULL);
	}

	/* Fill in the extent descriptor and return it to the caller. */
	simple_lock_init(&ex->ex_slock);
	LIST_INIT(&ex->ex_regions);
	ex->ex_name = name;
	ex->ex_start = start;
	ex->ex_end = end;
	ex->ex_mtype = mtype;
	ex->ex_flags = 0;
	if (fixed_extent)
		ex->ex_flags |= EXF_FIXED;
	if (flags & EX_NOCOALESCE)
		ex->ex_flags |= EXF_NOCOALESCE;
	return (ex);
}

/*
 * Destroy an extent map.
 * Since we're freeing the data, there can't be any references
 * so we don't need any locking.
 */
void
extent_destroy(ex)
	struct extent *ex;
{
	struct extent_region *rp, *orp;

#ifdef DIAGNOSTIC
	/* Check arguments. */
	if (ex == NULL)
		panic("extent_destroy: NULL extent");
#endif

	/* Free all region descriptors in extent. */
	for (rp = ex->ex_regions.lh_first; rp != NULL; ) {
		orp = rp;
		rp = rp->er_link.le_next;
		LIST_REMOVE(orp, er_link);
		extent_free_region_descriptor(ex, orp);
	}

	/* If we're not a fixed extent, free the extent descriptor itself. */
	if ((ex->ex_flags & EXF_FIXED) == 0)
		free(ex, ex->ex_mtype);
}

/*
 * Insert a region descriptor into the sorted region list after the
 * entry "after" or at the head of the list (if "after" is NULL).
 * The region descriptor we insert is passed in "rp".  We must
 * allocate the region descriptor before calling this function!
 * If we don't need the region descriptor, it will be freed here.
 */
static void
extent_insert_and_optimize(ex, start, size, flags, after, rp)
	struct extent *ex;
	u_long start, size;
	int flags;
	struct extent_region *after, *rp;
{
	struct extent_region *nextr;
	int appended = 0;

	if (after == NULL) {
		/*
		 * We're the first in the region list.  If there's
		 * a region after us, attempt to coalesce to save
		 * descriptor overhead.
		 */
		if (((ex->ex_flags & EXF_NOCOALESCE) == 0) &&
		    (ex->ex_regions.lh_first != NULL) &&
		    ((start + size) == ex->ex_regions.lh_first->er_start)) {
			/*
			 * We can coalesce.  Prepend us to the first region.
			 */
			ex->ex_regions.lh_first->er_start = start;
			extent_free_region_descriptor(ex, rp);
			return;
		}

		/*
		 * Can't coalesce.  Fill in the region descriptor
		 * in, and insert us at the head of the region list.
		 */
		rp->er_start = start;
		rp->er_end = start + (size - 1);
		LIST_INSERT_HEAD(&ex->ex_regions, rp, er_link);
		return;
	}

	/*
	 * If EXF_NOCOALESCE is set, coalescing is disallowed.
	 */
	if (ex->ex_flags & EXF_NOCOALESCE)
		goto cant_coalesce;

	/*
	 * Attempt to coalesce with the region before us.
	 */
	if ((after->er_end + 1) == start) {
		/*
		 * We can coalesce.  Append ourselves and make
		 * note of it.
		 */
		after->er_end = start + (size - 1);
		appended = 1;
	}

	/*
	 * Attempt to coalesce with the region after us.
	 */
	if ((after->er_link.le_next != NULL) &&
	    ((start + size) == after->er_link.le_next->er_start)) {
		/*
		 * We can coalesce.  Note that if we appended ourselves
		 * to the previous region, we exactly fit the gap, and
		 * can free the "next" region descriptor.
		 */
		if (appended) {
			/*
			 * Yup, we can free it up.
			 */
			after->er_end = after->er_link.le_next->er_end;
			nextr = after->er_link.le_next;
			LIST_REMOVE(nextr, er_link);
			extent_free_region_descriptor(ex, nextr);
		} else {
			/*
			 * Nope, just prepend us to the next region.
			 */
			after->er_link.le_next->er_start = start;
		}

		extent_free_region_descriptor(ex, rp);
		return;
	}

	/*
	 * We weren't able to coalesce with the next region, but
	 * we don't need to allocate a region descriptor if we
	 * appended ourselves to the previous region.
	 */
	if (appended) {
		extent_free_region_descriptor(ex, rp);
		return;
	}

 cant_coalesce:

	/*
	 * Fill in the region descriptor and insert ourselves
	 * into the region list.
	 */
	rp->er_start = start;
	rp->er_end = start + (size - 1);
	LIST_INSERT_AFTER(after, rp, er_link);
}

/*
 * Allocate a specific region in an extent map.
 */
int
extent_alloc_region(ex, start, size, flags)
	struct extent *ex;
	u_long start, size;
	int flags;
{
	struct extent_region *rp, *last, *myrp;
	u_long end = start + (size - 1);
	int error;

#ifdef DIAGNOSTIC
	/* Check arguments. */
	if (ex == NULL)
		panic("extent_alloc_region: NULL extent");
	if (size < 1) {
		printf("extent_alloc_region: extent `%s', size 0x%lx\n",
		    ex->ex_name, size);
		panic("extent_alloc_region: bad size");
	}
	if (end < start) {
		printf(
		 "extent_alloc_region: extent `%s', start 0x%lx, size 0x%lx\n",
		 ex->ex_name, start, size);
		panic("extent_alloc_region: overflow");
	}
#endif

	/*
	 * Make sure the requested region lies within the
	 * extent.
	 *
	 * We don't lock to check the range, because those values
	 * are never modified, and if another thread deletes the
	 * extent, we're screwed anyway.
	 */
	if ((start < ex->ex_start) || (end > ex->ex_end)) {
#ifdef DIAGNOSTIC
		printf("extent_alloc_region: extent `%s' (0x%lx - 0x%lx)\n",
		    ex->ex_name, ex->ex_start, ex->ex_end);
		printf("extent_alloc_region: start 0x%lx, end 0x%lx\n",
		    start, end);
		panic("extent_alloc_region: region lies outside extent");
#else
		return (EINVAL);
#endif
	}

	/*
	 * Allocate the region descriptor.  It will be freed later
	 * if we can coalesce with another region.  Don't lock before
	 * here!  This could block.
	 */
	myrp = extent_alloc_region_descriptor(ex, flags);
	if (myrp == NULL) {
#ifdef DIAGNOSTIC
		printf(
		    "extent_alloc_region: can't allocate region descriptor\n");
#endif
		return (ENOMEM);
	}

 alloc_start:
	simple_lock(&ex->ex_slock);

	/*
	 * Attempt to place ourselves in the desired area of the
	 * extent.  We save ourselves some work by keeping the list sorted.
	 * In other words, if the start of the current region is greater
	 * than the end of our region, we don't have to search any further.
	 */

	/*
	 * Keep a pointer to the last region we looked at so
	 * that we don't have to traverse the list again when
	 * we insert ourselves.  If "last" is NULL when we
	 * finally insert ourselves, we go at the head of the
	 * list.  See extent_insert_and_optimize() for details.
	 */
	last = NULL;

	for (rp = ex->ex_regions.lh_first; rp != NULL;
	    rp = rp->er_link.le_next) {
		if (rp->er_start > end) {
			/*
			 * We lie before this region and don't
			 * conflict.
			 */
			break;
		}

		/*
		 * The current region begins before we end.
		 * Check for a conflict.
		 */
		if (rp->er_end >= start) {
			/*
			 * We conflict.  If we can (and want to) wait,
			 * do so.
			 */
			if (flags & EX_WAITSPACE) {
				ex->ex_flags |= EXF_WANTED;
				error = ltsleep(ex,
				    PNORELOCK | PRIBIO | ((flags & EX_CATCH) ? PCATCH : 0),
				    "extnt", 0, &ex->ex_slock);
				if (error)
					return (error);
				goto alloc_start;
			}
			extent_free_region_descriptor(ex, myrp);
			simple_unlock(&ex->ex_slock);
			return (EAGAIN);
		}
		/*
		 * We don't conflict, but this region lies before
		 * us.  Keep a pointer to this region, and keep
		 * trying.
		 */
		last = rp;
	}

	/*
	 * We don't conflict with any regions.  "last" points
	 * to the region we fall after, or is NULL if we belong
	 * at the beginning of the region list.  Insert ourselves.
	 */
	extent_insert_and_optimize(ex, start, size, flags, last, myrp);
	simple_unlock(&ex->ex_slock);
	return (0);
}

/*
 * Macro to check (x + y) <= z.  This check is designed to fail
 * if an overflow occurs.
 */
#define LE_OV(x, y, z)	((((x) + (y)) >= (x)) && (((x) + (y)) <= (z)))

/*
 * Allocate a region in an extent map subregion.
 *
 * If EX_FAST is specified, we return the first fit in the map.
 * Otherwise, we try to minimize fragmentation by finding the
 * smallest gap that will hold the request.
 *
 * The allocated region is aligned to "alignment", which must be
 * a power of 2.
 */
int
extent_alloc_subregion1(ex, substart, subend, size, alignment, skew, boundary,
    flags, result)
	struct extent *ex;
	u_long substart, subend, size, alignment, skew, boundary;
	int flags;
	u_long *result;
{
	struct extent_region *rp, *myrp, *last, *bestlast;
	u_long newstart, newend, beststart, bestovh, ovh;
	u_long dontcross;
	int error;

#ifdef DIAGNOSTIC
	/*
	 * Check arguments.
	 *
	 * We don't lock to check these, because these values
	 * are never modified, and if another thread deletes the
	 * extent, we're screwed anyway.
	 */
	if (ex == NULL)
		panic("extent_alloc_subregion: NULL extent");
	if (result == NULL)
		panic("extent_alloc_subregion: NULL result pointer");
	if ((substart < ex->ex_start) || (substart > ex->ex_end) ||
	    (subend > ex->ex_end) || (subend < ex->ex_start)) {
  printf("extent_alloc_subregion: extent `%s', ex_start 0x%lx, ex_end 0x%lx\n",
		    ex->ex_name, ex->ex_start, ex->ex_end);
		printf("extent_alloc_subregion: substart 0x%lx, subend 0x%lx\n",
		    substart, subend);
		panic("extent_alloc_subregion: bad subregion");
	}
	if ((size < 1) || ((size - 1) > (subend - substart))) {
		printf("extent_alloc_subregion: extent `%s', size 0x%lx\n",
		    ex->ex_name, size);
		panic("extent_alloc_subregion: bad size");
	}
	if (alignment == 0)
		panic("extent_alloc_subregion: bad alignment");
	if (boundary && (boundary < size)) {
		printf(
		    "extent_alloc_subregion: extent `%s', size 0x%lx,
		    boundary 0x%lx\n", ex->ex_name, size, boundary);
		panic("extent_alloc_subregion: bad boundary");
	}
#endif

	/*
	 * Allocate the region descriptor.  It will be freed later
	 * if we can coalesce with another region.  Don't lock before
	 * here!  This could block.
	 */
	myrp = extent_alloc_region_descriptor(ex, flags);
	if (myrp == NULL) {
#ifdef DIAGNOSTIC
		printf(
		 "extent_alloc_subregion: can't allocate region descriptor\n");
#endif
		return (ENOMEM);
	}

 alloc_start:
	simple_lock(&ex->ex_slock);

	/*
	 * Keep a pointer to the last region we looked at so
	 * that we don't have to traverse the list again when
	 * we insert ourselves.  If "last" is NULL when we