FreeBSD-5.3/sys/fs/pseudofs/pseudofs_fileno.c
/*-
* Copyright (c) 2001 Dag-Erling Coïdan Smørgrav
* All rights reserved.
*
* 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
* in this position and unchanged.
* 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. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*
* $FreeBSD: src/sys/fs/pseudofs/pseudofs_fileno.c,v 1.10 2003/04/29 13:36:01 kan Exp $
*/
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/sysctl.h>
#include <fs/pseudofs/pseudofs.h>
#include <fs/pseudofs/pseudofs_internal.h>
static MALLOC_DEFINE(M_PFSFILENO, "pfs_fileno", "pseudofs fileno bitmap");
static struct mtx pfs_fileno_mutex;
#define PFS_BITMAP_SIZE 4096
#define PFS_SLOT_BITS (int)(sizeof(unsigned int) * CHAR_BIT)
#define PFS_BITMAP_BITS (PFS_BITMAP_SIZE * PFS_SLOT_BITS)
struct pfs_bitmap {
u_int32_t pb_offset;
int pb_used;
unsigned int pb_bitmap[PFS_BITMAP_SIZE];
struct pfs_bitmap *pb_next;
};
/*
* Initialization
*/
void
pfs_fileno_load(void)
{
mtx_init(&pfs_fileno_mutex, "pseudofs_fileno", NULL, MTX_DEF);
}
/*
* Teardown
*/
void
pfs_fileno_unload(void)
{
mtx_destroy(&pfs_fileno_mutex);
}
/*
* Initialize fileno bitmap
*/
void
pfs_fileno_init(struct pfs_info *pi)
{
struct pfs_bitmap *pb;
MALLOC(pb, struct pfs_bitmap *, sizeof *pb,
M_PFSFILENO, M_WAITOK|M_ZERO);
mtx_lock(&pi->pi_mutex);
pb->pb_bitmap[0] = 07;
pb->pb_used = 3;
pi->pi_bitmap = pb;
pi->pi_root->pn_fileno = 2;
mtx_unlock(&pi->pi_mutex);
}
/*
* Tear down fileno bitmap
*/
void
pfs_fileno_uninit(struct pfs_info *pi)
{
struct pfs_bitmap *pb, *npb;
int used;
mtx_lock(&pi->pi_mutex);
pb = pi->pi_bitmap;
pi->pi_bitmap = NULL;
mtx_unlock(&pi->pi_mutex);
for (used = 0; pb; pb = npb) {
npb = pb->pb_next;
used += pb->pb_used;
FREE(pb, M_PFSFILENO);
}
#if 0
/* we currently don't reclaim filenos */
if (used > 2)
printf("WARNING: %d file numbers still in use\n", used);
#endif
}
/*
* Get the next available file number
*/
static u_int32_t
pfs_get_fileno(struct pfs_info *pi)
{
struct pfs_bitmap *pb, *ppb;
u_int32_t fileno;
unsigned int *p;
int i;
mtx_lock(&pi->pi_mutex);
/* look for the first page with free bits */
for (ppb = NULL, pb = pi->pi_bitmap; pb; ppb = pb, pb = pb->pb_next)
if (pb->pb_used != PFS_BITMAP_BITS)
break;
/* out of pages? */
if (pb == NULL) {
mtx_unlock(&pi->pi_mutex);
MALLOC(pb, struct pfs_bitmap *, sizeof *pb,
M_PFSFILENO, M_WAITOK|M_ZERO);
mtx_lock(&pi->pi_mutex);
/* protect against possible race */
while (ppb->pb_next)
ppb = ppb->pb_next;
pb->pb_offset = ppb->pb_offset + PFS_BITMAP_BITS;
ppb->pb_next = pb;
}
/* find the first free slot */
for (i = 0; i < PFS_BITMAP_SIZE; ++i)
if (pb->pb_bitmap[i] != UINT_MAX)
break;
/* find the first available bit and flip it */
fileno = pb->pb_offset + i * PFS_SLOT_BITS;
p = &pb->pb_bitmap[i];
for (i = 0; i < PFS_SLOT_BITS; ++i, ++fileno)
if ((*p & (unsigned int)(1 << i)) == 0)
break;
KASSERT(i < PFS_SLOT_BITS,
("slot has free bits, yet doesn't"));
*p |= (unsigned int)(1 << i);
++pb->pb_used;
mtx_unlock(&pi->pi_mutex);
return fileno;
}
/*
* Free a file number
*/
static void
pfs_free_fileno(struct pfs_info *pi, u_int32_t fileno)
{
struct pfs_bitmap *pb;
unsigned int *p;
int i;
mtx_lock(&pi->pi_mutex);
/* find the right page */
for (pb = pi->pi_bitmap;
pb && fileno >= PFS_BITMAP_BITS;
pb = pb->pb_next, fileno -= PFS_BITMAP_BITS)
/* nothing */ ;
KASSERT(pb,
("fileno isn't in any bitmap"));
/* find the right bit in the right slot and flip it */
p = &pb->pb_bitmap[fileno / PFS_SLOT_BITS];
i = fileno % PFS_SLOT_BITS;
KASSERT(*p & (unsigned int)(1 << i),
("fileno is already free"));
*p &= ~((unsigned int)(1 << i));
--pb->pb_used;
mtx_unlock(&pi->pi_mutex);
printf("pfs_free_fileno(): reclaimed %d\n", fileno);
}
/*
* Allocate a file number
*/
void
pfs_fileno_alloc(struct pfs_info *pi, struct pfs_node *pn)
{
/* make sure our parent has a file number */
if (pn->pn_parent && !pn->pn_parent->pn_fileno)
pfs_fileno_alloc(pi, pn->pn_parent);
switch (pn->pn_type) {
case pfstype_root:
case pfstype_dir:
case pfstype_file:
case pfstype_symlink:
case pfstype_procdir:
pn->pn_fileno = pfs_get_fileno(pi);
break;
case pfstype_this:
KASSERT(pn->pn_parent != NULL,
("pfstype_this node has no parent"));
pn->pn_fileno = pn->pn_parent->pn_fileno;
break;
case pfstype_parent:
KASSERT(pn->pn_parent != NULL,
("pfstype_parent node has no parent"));
if (pn->pn_parent == pi->pi_root) {
pn->pn_fileno = pn->pn_parent->pn_fileno;
break;
}
KASSERT(pn->pn_parent->pn_parent != NULL,
("pfstype_parent node has no grandparent"));
pn->pn_fileno = pn->pn_parent->pn_parent->pn_fileno;
break;
case pfstype_none:
KASSERT(0,
("pfs_fileno_alloc() called for pfstype_none node"));
break;
}
#if 0
printf("pfs_fileno_alloc(): %s: ", pi->pi_name);
if (pn->pn_parent) {
if (pn->pn_parent->pn_parent) {
printf("%s/", pn->pn_parent->pn_parent->pn_name);
}
printf("%s/", pn->pn_parent->pn_name);
}
printf("%s -> %d\n", pn->pn_name, pn->pn_fileno);
#endif
}
/*
* Release a file number
*/
void
pfs_fileno_free(struct pfs_info *pi, struct pfs_node *pn)
{
switch (pn->pn_type) {
case pfstype_root:
case pfstype_dir:
case pfstype_file:
case pfstype_symlink:
case pfstype_procdir:
pfs_free_fileno(pi, pn->pn_fileno);
break;
case pfstype_this:
case pfstype_parent:
/* ignore these, as they don't "own" their file number */
break;
case pfstype_none:
KASSERT(0,
("pfs_fileno_free() called for pfstype_none node"));
break;
}
}