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minix/servers/vm/slaballoc.c
Ben Gras 49eb1f4806 vm: new secondary cache code 
Primary purpose of change: to support the mmap implementation, VM must
know both (a) about some block metadata for FS cache blocks, i.e.
inode numbers and inode offsets where applicable; and (b) know about
*all* cache blocks, i.e.  also of the FS primary caches and not just
the blocks that spill into the secondary one. This changes the
interface and VM data structures.

This change is only for the interface (libminixfs) and VM data
structures; the filesystem code is unmodified, so although the
secondary cache will be used as normal, blocks will not be annotated
with inode information until the FS is modified to provide this
information. Until it is modified, mmap of files will fail gracefully
on such filesystems.

This is indicated to VFS/VM by returning ENOSYS for REQ_PEEK.

Change-Id: I1d2df6c485e6c5e89eb28d9055076cc02629594e
2013-04-24 10:18:16 +00:00

527 lines
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C
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#define _SYSTEM 1
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/config.h>
#include <minix/const.h>
#include <minix/ds.h>
#include <minix/endpoint.h>
#include <minix/keymap.h>
#include <minix/minlib.h>
#include <minix/type.h>
#include <minix/ipc.h>
#include <minix/sysutil.h>
#include <minix/syslib.h>
#include <minix/bitmap.h>
#include <minix/debug.h>
#include <assert.h>
#include <errno.h>
#include <string.h>
#include <env.h>
#include <sys/param.h>
#include "glo.h"
#include "proto.h"
#include "util.h"
#include "sanitycheck.h"
#define SLABSIZES 200
#define ITEMSPERPAGE(bytes) (DATABYTES / (bytes))
#define ELBITS (sizeof(element_t)*8)
#define BITPAT(b) (1UL << ((b) % ELBITS))
#define BITEL(f, b) (f)->sdh.usebits[(b)/ELBITS]
#define OFF(f, b) assert(!GETBIT(f, b))
#define ON(f, b) assert(GETBIT(f, b))
#if MEMPROTECT
#define SLABDATAWRITABLE(data, wr) do { \
assert(data->sdh.writable == WRITABLE_NONE); \
assert(wr != WRITABLE_NONE); \
vm_pagelock(data, 0); \
data->sdh.writable = wr; \
} while(0)
#define SLABDATAUNWRITABLE(data) do { \
assert(data->sdh.writable != WRITABLE_NONE); \
data->sdh.writable = WRITABLE_NONE; \
vm_pagelock(data, 1); \
} while(0)
#define SLABDATAUSE(data, code) do { \
SLABDATAWRITABLE(data, WRITABLE_HEADER); \
code \
SLABDATAUNWRITABLE(data); \
} while(0)
#else
#define SLABDATAWRITABLE(data, wr)
#define SLABDATAUNWRITABLE(data)
#define SLABDATAUSE(data, code) do { code } while(0)
#endif
#define GETBIT(f, b) (BITEL(f,b) & BITPAT(b))
#define SETBIT(f, b) {OFF(f,b); SLABDATAUSE(f, BITEL(f,b)|= BITPAT(b); (f)->sdh.nused++;); }
#define CLEARBIT(f, b) {ON(f, b); SLABDATAUSE(f, BITEL(f,b)&=~BITPAT(b); (f)->sdh.nused--; (f)->sdh.freeguess = (b);); }
#define OBJALIGN 8
#define MINSIZE 8
#define MAXSIZE (SLABSIZES-1+MINSIZE)
#define USEELEMENTS (1+(VM_PAGE_SIZE/MINSIZE/8))
static int pages = 0;
typedef u8_t element_t;
#define BITS_FULL (~(element_t)0)
typedef element_t elements_t[USEELEMENTS];
/* This file is too low-level to have global SANITYCHECKs everywhere,
* as the (other) data structures are often necessarily in an
* inconsistent state during a slaballoc() / slabfree(). So only do
* our own sanity checks here, with SLABSANITYCHECK.
*/
/* Special writable values. */
#define WRITABLE_NONE -2
#define WRITABLE_HEADER -1
struct sdh {
#if SANITYCHECKS
u32_t magic1;
#endif
int freeguess;
struct slabdata *next, *prev;
elements_t usebits;
phys_bytes phys;
#if SANITYCHECKS
int writable; /* data item number or WRITABLE_* */
u32_t magic2;
#endif
u16_t nused; /* Number of data items used in this slab. */
};
#define DATABYTES (VM_PAGE_SIZE-sizeof(struct sdh))
#define MAGIC1 0x1f5b842f
#define MAGIC2 0x8bb5a420
#define JUNK 0xdeadbeef
#define NOJUNK 0xc0ffee
static struct slabheader {
struct slabdata {
u8_t data[DATABYTES];
struct sdh sdh;
} *list_head;
} slabs[SLABSIZES];
static int objstats(void *, int, struct slabheader **, struct slabdata
**, int *);
#define GETSLAB(b, s) { \
int i; \
assert((b) >= MINSIZE); \
i = (b) - MINSIZE; \
assert((i) < SLABSIZES); \
assert((i) >= 0); \
s = &slabs[i]; \
}
/* move slabdata nw to slabheader sl under list number l. */
#define ADDHEAD(nw, sl) { \
SLABDATAUSE(nw, \
(nw)->sdh.next = sl->list_head; \
(nw)->sdh.prev = NULL;); \
sl->list_head = nw; \
if((nw)->sdh.next) { \
SLABDATAUSE((nw)->sdh.next, \
(nw)->sdh.next->sdh.prev = (nw);); \
} \
}
#define UNLINKNODE(node) { \
struct slabdata *next, *prev; \
prev = (node)->sdh.prev; \
next = (node)->sdh.next; \
if(prev) { SLABDATAUSE(prev, prev->sdh.next = next;); } \
if(next) { SLABDATAUSE(next, next->sdh.prev = prev;); } \
}
static struct slabdata *newslabdata()
{
struct slabdata *n;
phys_bytes p;
assert(sizeof(*n) == VM_PAGE_SIZE);
if(!(n = vm_allocpage(&p, VMP_SLAB))) {
printf("newslabdata: vm_allocpage failed\n");
return NULL;
}
memset(n->sdh.usebits, 0, sizeof(n->sdh.usebits));
pages++;
n->sdh.phys = p;
#if SANITYCHECKS
n->sdh.magic1 = MAGIC1;
n->sdh.magic2 = MAGIC2;
#endif
n->sdh.nused = 0;
n->sdh.freeguess = 0;
#if SANITYCHECKS
n->sdh.writable = WRITABLE_HEADER;
SLABDATAUNWRITABLE(n);
#endif
return n;
}
#if SANITYCHECKS
/*===========================================================================*
* checklist *
*===========================================================================*/
static int checklist(char *file, int line,
struct slabheader *s, int bytes)
{
struct slabdata *n = s->list_head;
int ch = 0;
while(n) {
int count = 0, i;
#if SANITYCHECKS
MYASSERT(n->sdh.magic1 == MAGIC1);
MYASSERT(n->sdh.magic2 == MAGIC2);
#endif
MYASSERT(usedpages_add(n->sdh.phys, VM_PAGE_SIZE) == OK);
if(n->sdh.prev)
MYASSERT(n->sdh.prev->sdh.next == n);
else
MYASSERT(s->list_head == n);
if(n->sdh.next) MYASSERT(n->sdh.next->sdh.prev == n);
for(i = 0; i < USEELEMENTS*8; i++)
if(i >= ITEMSPERPAGE(bytes))
MYASSERT(!GETBIT(n, i));
else
if(GETBIT(n,i))
count++;
MYASSERT(count == n->sdh.nused);
ch += count;
n = n->sdh.next;
}
return ch;
}
/*===========================================================================*
* void slab_sanitycheck *
*===========================================================================*/
void slab_sanitycheck(char *file, int line)
{
int s;
for(s = 0; s < SLABSIZES; s++) {
checklist(file, line, &slabs[s], s + MINSIZE);
}
}
/*===========================================================================*
* int slabsane *
*===========================================================================*/
int slabsane_f(char *file, int line, void *mem, int bytes)
{
struct slabheader *s;
struct slabdata *f;
int i;
bytes = roundup(bytes, OBJALIGN);
return (objstats(mem, bytes, &s, &f, &i) == OK);
}
#endif
#if SANITYCHECKS
static int nojunkwarning = 0;
#endif
/*===========================================================================*
* void *slaballoc *
*===========================================================================*/
void *slaballoc(int bytes)
{
int i;
int count = 0;
struct slabheader *s;
struct slabdata *newslab;
char *ret;
bytes = roundup(bytes, OBJALIGN);
SLABSANITYCHECK(SCL_FUNCTIONS);
/* Retrieve entry in slabs[]. */
GETSLAB(bytes, s);
assert(s);
if(!(newslab = s->list_head)) {
/* Make sure there is something on the freelist. */
newslab = newslabdata();
if(!newslab) return NULL;
ADDHEAD(newslab, s);
assert(newslab->sdh.nused == 0);
} else assert(newslab->sdh.nused > 0);
assert(newslab->sdh.nused < ITEMSPERPAGE(bytes));
SLABSANITYCHECK(SCL_DETAIL);
#if SANITYCHECKS
assert(newslab->sdh.magic1 == MAGIC1);
assert(newslab->sdh.magic2 == MAGIC2);
#endif
for(i = newslab->sdh.freeguess;
count < ITEMSPERPAGE(bytes); count++, i++) {
i = i % ITEMSPERPAGE(bytes);
if(!GETBIT(newslab, i))
break;
}
SLABSANITYCHECK(SCL_FUNCTIONS);
assert(count < ITEMSPERPAGE(bytes));
assert(i >= 0 && i < ITEMSPERPAGE(bytes));
SETBIT(newslab, i);
if(newslab->sdh.nused == ITEMSPERPAGE(bytes)) {
UNLINKNODE(newslab);
s->list_head = newslab->sdh.next;
}
ret = ((char *) newslab) + i*bytes;
#if SANITYCHECKS
#if MEMPROTECT
nojunkwarning++;
slabunlock(ret, bytes);
nojunkwarning--;
assert(!nojunkwarning);
#endif
*(u32_t *) ret = NOJUNK;
#if MEMPROTECT
slablock(ret, bytes);
#endif
#endif
SLABDATAUSE(newslab, newslab->sdh.freeguess = i+1;);
#if SANITYCHECKS
if(bytes >= SLABSIZES+MINSIZE) {
printf("slaballoc: odd, bytes %d?\n", bytes);
}
if(!slabsane_f(__FILE__, __LINE__, ret, bytes))
panic("slaballoc: slabsane failed");
#endif
assert(!((vir_bytes) ret % OBJALIGN));
return ret;
}
/*===========================================================================*
* int objstats *
*===========================================================================*/
static inline int objstats(void *mem, int bytes,
struct slabheader **sp, struct slabdata **fp, int *ip)
{
#if SANITYCHECKS
#define OBJSTATSCHECK(cond) \
if(!(cond)) { \
printf("VM: objstats: %s failed for ptr %p, %d bytes\n", \
#cond, mem, bytes); \
return EINVAL; \
}
#else
#define OBJSTATSCHECK(cond)
#endif
struct slabheader *s;
struct slabdata *f;
int i;
assert(!(bytes % OBJALIGN));
OBJSTATSCHECK((char *) mem >= (char *) VM_PAGE_SIZE);
#if SANITYCHECKS
if(*(u32_t *) mem == JUNK && !nojunkwarning) {
util_stacktrace();
printf("VM: WARNING: JUNK seen in slab object, likely freed\n");
}
#endif
/* Retrieve entry in slabs[]. */
GETSLAB(bytes, s);
/* Round address down to VM_PAGE_SIZE boundary to get header. */
f = (struct slabdata *) ((char *) mem - (vir_bytes) mem % VM_PAGE_SIZE);
#if SANITYCHECKS
OBJSTATSCHECK(f->sdh.magic1 == MAGIC1);
OBJSTATSCHECK(f->sdh.magic2 == MAGIC2);
#endif
/* Make sure it's in range. */
OBJSTATSCHECK((char *) mem >= (char *) f->data);
OBJSTATSCHECK((char *) mem < (char *) f->data + sizeof(f->data));
/* Get position. */
i = (char *) mem - (char *) f->data;
OBJSTATSCHECK(!(i % bytes));
i = i / bytes;
/* Make sure it is marked as allocated. */
OBJSTATSCHECK(GETBIT(f, i));
/* return values */
*ip = i;
*fp = f;
*sp = s;
return OK;
}
/*===========================================================================*
* void *slabfree *
*===========================================================================*/
void slabfree(void *mem, int bytes)
{
int i;
struct slabheader *s;
struct slabdata *f;
bytes = roundup(bytes, OBJALIGN);
SLABSANITYCHECK(SCL_FUNCTIONS);
if(objstats(mem, bytes, &s, &f, &i) != OK) {
panic("slabfree objstats failed");
}
#if SANITYCHECKS
if(*(u32_t *) mem == JUNK) {
printf("VM: WARNING: likely double free, JUNK seen\n");
}
#endif
#if SANITYCHECKS
#if MEMPROTECT
slabunlock(mem, bytes);
#endif
#if JUNKFREE
memset(mem, 0xa6, bytes);
#endif
*(u32_t *) mem = JUNK;
nojunkwarning++;
#if MEMPROTECT
slablock(mem, bytes);
#endif
nojunkwarning--;
assert(!nojunkwarning);
#endif
/* Free this data. */
CLEARBIT(f, i);
/* Check if this slab changes lists. */
if(f->sdh.nused == 0) {
UNLINKNODE(f);
if(f == s->list_head) s->list_head = f->sdh.next;
vm_freepages((vir_bytes) f, 1);
SLABSANITYCHECK(SCL_DETAIL);
} else if(f->sdh.nused == ITEMSPERPAGE(bytes)-1) {
ADDHEAD(f, s);
}
SLABSANITYCHECK(SCL_FUNCTIONS);
return;
}
/*===========================================================================*
* void *slablock *
*===========================================================================*/
void slablock(void *mem, int bytes)
{
int i;
struct slabheader *s;
struct slabdata *f;
bytes = roundup(bytes, OBJALIGN);
if(objstats(mem, bytes, &s, &f, &i) != OK)
panic("slablock objstats failed");
SLABDATAUNWRITABLE(f);
return;
}
/*===========================================================================*
* void *slabunlock *
*===========================================================================*/
void slabunlock(void *mem, int bytes)
{
int i;
struct slabheader *s;
struct slabdata *f;
bytes = roundup(bytes, OBJALIGN);
if(objstats(mem, bytes, &s, &f, &i) != OK)
panic("slabunlock objstats failed");
SLABDATAWRITABLE(f, i);
return;
}
#if SANITYCHECKS
/*===========================================================================*
* void slabstats *
*===========================================================================*/
void slabstats(void)
{
int s, totalbytes = 0;
static int n;
n++;
if(n%1000) return;
for(s = 0; s < SLABSIZES; s++) {
int b, t;
b = s + MINSIZE;
t = checklist(__FILE__, __LINE__, &slabs[s], b);
if(t > 0) {
int bytes = t * b;
printf("VMSTATS: %2d slabs: %d (%dkB)\n", b, t, bytes/1024);
totalbytes += bytes;
}
}
if(pages > 0) {
printf("VMSTATS: %dK net used in slab objects in %d pages (%dkB): %d%% utilization\n",
totalbytes/1024, pages, pages*VM_PAGE_SIZE/1024,
100 * totalbytes / (pages*VM_PAGE_SIZE));
}
}
#endif
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