path: root/fs/ntfs/runlist.c

/**
 * runlist.c - NTFS runlist handling code.  Part of the Linux-NTFS project.
 *
 * Copyright (c) 2001-2005 Anton Altaparmakov
 * Copyright (c) 2002 Richard Russon
 *
 * This program/include file 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; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program/include file is distributed in the hope that it will 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 (in the main directory of the Linux-NTFS
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "debug.h"
#include "dir.h"
#include "endian.h"
#include "malloc.h"
#include "ntfs.h"

/**
 * ntfs_rl_mm - runlist memmove
 *
 * It is up to the caller to serialize access to the runlist @base.
 */
static inline void ntfs_rl_mm(runlist_element *base, int dst, int src,
		int size)
{
	if (likely((dst != src) && (size > 0)))
		memmove(base + dst, base + src, size * sizeof(*base));
}

/**
 * ntfs_rl_mc - runlist memory copy
 *
 * It is up to the caller to serialize access to the runlists @dstbase and
 * @srcbase.
 */
static inline void ntfs_rl_mc(runlist_element *dstbase, int dst,
		runlist_element *srcbase, int src, int size)
{
	if (likely(size > 0))
		memcpy(dstbase + dst, srcbase + src, size * sizeof(*dstbase));
}

/**
 * ntfs_rl_realloc - Reallocate memory for runlists
 * @rl:		original runlist
 * @old_size:	number of runlist elements in the original runlist @rl
 * @new_size:	number of runlist elements we need space for
 *
 * As the runlists grow, more memory will be required.  To prevent the
 * kernel having to allocate and reallocate large numbers of small bits of
 * memory, this function returns an entire page of memory.
 *
 * It is up to the caller to serialize access to the runlist @rl.
 *
 * N.B.  If the new allocation doesn't require a different number of pages in
 *       memory, the function will return the original pointer.
 *
 * On success, return a pointer to the newly allocated, or recycled, memory.
 * On error, return -errno. The following error codes are defined:
 *	-ENOMEM	- Not enough memory to allocate runlist array.
 *	-EINVAL	- Invalid parameters were passed in.
 */
static inline runlist_element *ntfs_rl_realloc(runlist_element *rl,
		int old_size, int new_size)
{
	runlist_element *new_rl;

	old_size = PAGE_ALIGN(old_size * sizeof(*rl));
	new_size = PAGE_ALIGN(new_size * sizeof(*rl));
	if (old_size == new_size)
		return rl;

	new_rl = ntfs_malloc_nofs(new_size);
	if (unlikely(!new_rl))
		return ERR_PTR(-ENOMEM);

	if (likely(rl != NULL)) {
		if (unlikely(old_size > new_size))
			old_size = new_size;
		memcpy(new_rl, rl, old_size);
		ntfs_free(rl);
	}
	return new_rl;
}

/**
 * ntfs_rl_realloc_nofail - Reallocate memory for runlists
 * @rl:		original runlist
 * @old_size:	number of runlist elements in the original runlist @rl
 * @new_size:	number of runlist elements we need space for
 *
 * As the runlists grow, more memory will be required.  To prevent the
 * kernel having to allocate and reallocate large numbers of small bits of
 * memory, this function returns an entire page of memory.
 *
 * This function guarantees that the allocation will succeed.  It will sleep
 * for as long as it takes to complete the allocation.
 *
 * It is up to the caller to serialize access to the runlist @rl.
 *
 * N.B.  If the new allocation doesn't require a different number of pages in
 *       memory, the function will return the original pointer.
 *
 * On success, return a pointer to the newly allocated, or recycled, memory.
 * On error, return -errno. The following error codes are defined:
 *	-ENOMEM	- Not enough memory to allocate runlist array.
 *	-EINVAL	- Invalid parameters were passed in.
 */
static inline runlist_element *ntfs_rl_realloc_nofail(runlist_element *rl,
		int old_size, int new_size)
{
	runlist_element *new_rl;

	old_size = PAGE_ALIGN(old_size * sizeof(*rl));
	new_size = PAGE_ALIGN(new_size * sizeof(*rl));
	if (old_size == new_size)
		return rl;

	new_rl = ntfs_malloc_nofs_nofail(new_size);
	BUG_ON(!new_rl);

	if (likely(rl != NULL)) {
		if (unlikely(old_size > new_size))
			old_size = new_size;
		memcpy(new_rl, rl, old_size);
		ntfs_free(rl);
	}
	return new_rl;
}

/**
 * ntfs_are_rl_mergeable - test if two runlists can be joined together
 * @dst:	original runlist
 * @src:	new runlist to test for mergeability with @dst
 *
 * Test if two runlists can be joined together. For this, their VCNs and LCNs
 * must be adjacent.
 *
 * It is up to the caller to serialize access to the runlists @dst and @src.
 *
 * Return: TRUE   Success, the runlists can be merged.
 *	   FALSE  Failure, the runlists cannot be merged.
 */
static inline BOOL ntfs_are_rl_mergeable(runlist_element *dst,
		runlist_element *src)
{
	BUG_ON(!dst);
	BUG_ON(!src);

	if ((dst->lcn < 0) || (src->lcn < 0)) {   /* Are we merging holes? */
		if (dst->lcn == LCN_HOLE && src->lcn == LCN_HOLE)
			return TRUE;