alistair23-linux/fs/xfs/kmem.c

/*
 * 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 <linux/mm.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include "time.h"
#include "kmem.h"
#include "xfs_message.h"

/*
 * Greedy allocation.  May fail and may return vmalloced memory.
 */
void *
kmem_zalloc_greedy(size_t *size, size_t minsize, size_t maxsize)
{
	void		*ptr;
	size_t		kmsize = maxsize;

	while (!(ptr = vzalloc(kmsize))) {
		if ((kmsize >>= 1) <= minsize)
			kmsize = minsize;
	}
	if (ptr)
		*size = kmsize;
	return ptr;
}

void *
kmem_alloc(size_t size, xfs_km_flags_t flags)
{
	int	retries = 0;
	gfp_t	lflags = kmem_flags_convert(flags);
	void	*ptr;

	do {
		ptr = kmalloc(size, lflags);
		if (ptr || (flags & (KM_MAYFAIL|KM_NOSLEEP)))
			return ptr;
		if (!(++retries % 100))
			xfs_err(NULL,
		"possible memory allocation deadlock in %s (mode:0x%x)",
					__func__, lflags);
		congestion_wait(BLK_RW_ASYNC, HZ/50);
	} while (1);
}

void *
kmem_zalloc_large(size_t size, xfs_km_flags_t flags)
{
	unsigned noio_flag = 0;
	void	*ptr;
	gfp_t	lflags;

	ptr = kmem_zalloc(size, flags | KM_MAYFAIL);
	if (ptr)
		return ptr;

	/*
	 * __vmalloc() will allocate data pages and auxillary structures (e.g.
	 * pagetables) with GFP_KERNEL, yet we may be under GFP_NOFS context
	 * here. Hence we need to tell memory reclaim that we are in such a
	 * context via PF_MEMALLOC_NOIO to prevent memory reclaim re-entering
	 * the filesystem here and potentially deadlocking.
	 */
	if ((current->flags & PF_FSTRANS) || (flags & KM_NOFS))
		noio_flag = memalloc_noio_save();

	lflags = kmem_flags_convert(flags);
	ptr = __vmalloc(size, lflags | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);

	if ((current->flags & PF_FSTRANS) || (flags & KM_NOFS))
		memalloc_noio_restore(noio_flag);

	return ptr;
}

void
kmem_free(const void *ptr)
{
	if (!is_vmalloc_addr(ptr)) {
		kfree(ptr);
	} else {
		vfree(ptr);
	}
}

void *
kmem_realloc(const void *ptr, size_t newsize, size_t oldsize,
	     xfs_km_flags_t flags)
{
	void	*new;

	new = kmem_alloc(newsize, flags);
	if (ptr) {
		if (new)
			memcpy(new, ptr,
				((oldsize < newsize) ? oldsize : newsize));
		kmem_free(ptr);
	}
	return new;
}

void *
kmem_zone_alloc(kmem_zone_t *zone, xfs_km_flags_t flags)
{
	int	retries = 0;
	gfp_t	lflags = kmem_flags_convert(flags);
	void	*ptr;

	do {
		ptr = kmem_cache_alloc(zone, lflags);
		if (ptr || (flags & (KM_MAYFAIL|KM_NOSLEEP)))
			return ptr;
		if (!(++retries % 100))
			xfs_err(NULL,
		"possible memory allocation deadlock in %s (mode:0x%x)",
					__func__, lflags);
		congestion_wait(BLK_RW_ASYNC, HZ/50);
	} while (1);
}