minix/servers/vm/cache.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

311 lines
6.6 KiB
C

/* File that implements the data structure, insert, lookup and remove
* functions for file system cache blocks.
*
* Cache blocks can be mapped into the memory of processes by the
* 'cache' and 'file' memory types.
*/
#include <assert.h>
#include <string.h>
#include <minix/hash.h>
#include "proto.h"
#include "vm.h"
#include "region.h"
#include "glo.h"
#include "cache.h"
/* cache datastructure */
#define HASHSIZE 65536
static struct cached_page *cache_hash_bydev[HASHSIZE];
static struct cached_page *cache_hash_byino[HASHSIZE];
static struct cached_page *lru_oldest = NULL, *lru_newest = NULL;
static u32_t cached_pages = 0;
static void lru_rm(struct cached_page *hb)
{
struct cached_page *newer = hb->newer, *older = hb->older;
assert(lru_newest);
assert(lru_oldest);
if(newer) {
assert(newer->older == hb);
newer->older = older;
}
if(older) {
assert(older->newer == hb);
older->newer = newer;
}
if(lru_newest == hb) { assert(!newer); lru_newest = older; }
if(lru_oldest == hb) { assert(!older); lru_oldest = newer; }
if(lru_newest) assert(lru_newest->newer == NULL);
if(lru_oldest) assert(lru_oldest->older == NULL);
cached_pages--;
}
static void lru_add(struct cached_page *hb)
{
if(lru_newest) {
assert(lru_oldest);
assert(!lru_newest->newer);
lru_newest->newer = hb;
} else {
assert(!lru_oldest);
lru_oldest = hb;
}
hb->older = lru_newest;
hb->newer = NULL;
lru_newest = hb;
cached_pages++;
}
void cache_lru_touch(struct cached_page *hb)
{
lru_rm(hb);
lru_add(hb);
}
static __inline u32_t makehash(u32_t p1, u64_t p2)
{
u32_t offlo = ex64lo(p2), offhi = ex64hi(p2),
v = 0x12345678;
hash_mix(p1, offlo, offhi);
hash_final(offlo, offhi, v);
return v % HASHSIZE;
}
#if CACHE_SANITY
void cache_sanitycheck_internal(void)
{
int h;
int n = 0;
int byino = 0;
int withino = 0;
int bydev_total = 0, lru_total = 0;
struct cached_page *cp;
for(h = 0; h < HASHSIZE; h++) {
for(cp = cache_hash_bydev[h]; cp; cp = cp->hash_next_dev) {
assert(cp->dev != NO_DEV);
assert(h == makehash(cp->dev, cp->dev_offset));
assert(cp == find_cached_page_bydev(cp->dev, cp->dev_offset, cp->ino, cp->ino_offset));
if(cp->ino != VMC_NO_INODE) withino++;
bydev_total++;
n++;
assert(n < 1500000);
}
for(cp = cache_hash_byino[h]; cp; cp = cp->hash_next_ino) {
assert(cp->dev != NO_DEV);
assert(cp->ino != VMC_NO_INODE);
assert(h == makehash(cp->ino, cp->ino_offset));
byino++;
n++;
assert(n < 1500000);
}
}
assert(byino == withino);
if(lru_newest) {
assert(lru_oldest);
assert(!lru_newest->newer);
assert(!lru_oldest->older);
} else {
assert(!lru_oldest);
}
for(cp = lru_oldest; cp; cp = cp->newer) {
struct cached_page *newer = cp->newer,
*older = cp->older;
if(newer) assert(newer->older == cp);
if(older) assert(older->newer == cp);
lru_total++;
}
assert(lru_total == bydev_total);
assert(lru_total == cached_pages);
}
#endif
#define rmhash_f(fname, nextfield) \
static void \
fname(struct cached_page *cp, struct cached_page **head) \
{ \
struct cached_page *hb; \
if(*head == cp) { *head = cp->nextfield; return; } \
for(hb = *head; hb && cp != hb->nextfield; hb = hb->nextfield) ; \
assert(hb); assert(hb->nextfield == cp); \
hb->nextfield = cp->nextfield; \
return; \
}
rmhash_f(rmhash_byino, hash_next_ino)
rmhash_f(rmhash_bydev, hash_next_dev)
static void addcache_byino(struct cached_page *hb)
{
int hv_ino = makehash(hb->ino, hb->ino_offset);
assert(hb->ino != VMC_NO_INODE);
hb->hash_next_ino = cache_hash_byino[hv_ino];
cache_hash_byino[hv_ino] = hb;
}
static void
update_inohash(struct cached_page *hb, ino_t ino, u64_t ino_off)
{
assert(ino != VMC_NO_INODE);
if(hb->ino != VMC_NO_INODE) {
int h = makehash(hb->ino, hb->ino_offset);
rmhash_byino(hb, &cache_hash_byino[h]);
}
hb->ino = ino;
hb->ino_offset = ino_off;
addcache_byino(hb);
}
struct cached_page *
find_cached_page_bydev(dev_t dev, u64_t dev_off, ino_t ino, u64_t ino_off, int touchlru)
{
struct cached_page *hb;
for(hb = cache_hash_bydev[makehash(dev, dev_off)]; hb; hb=hb->hash_next_dev) {
if(hb->dev == dev && hb->dev_offset == dev_off) {
if(ino != VMC_NO_INODE) {
if(hb->ino != ino || hb->ino_offset != ino_off) {
update_inohash(hb, ino, ino_off);
}
}
if(touchlru) cache_lru_touch(hb);
return hb;
}
}
return NULL;
}
struct cached_page *find_cached_page_byino(dev_t dev, ino_t ino, u64_t ino_off, int touchlru)
{
struct cached_page *hb;
assert(ino != VMC_NO_INODE);
assert(dev != NO_DEV);
for(hb = cache_hash_byino[makehash(ino, ino_off)]; hb; hb=hb->hash_next_ino) {
if(hb->dev == dev && hb->ino == ino && hb->ino_offset == ino_off) {
if(touchlru) cache_lru_touch(hb);
return hb;
}
}
return NULL;
}
int addcache(dev_t dev, u64_t dev_off, ino_t ino, u64_t ino_off, struct phys_block *pb)
{
int hv_dev;
struct cached_page *hb;
if(pb->flags & PBF_INCACHE) {
printf("VM: already in cache\n");
return EINVAL;
}
if(!SLABALLOC(hb)) {
printf("VM: no memory for cache node\n");
return ENOMEM;
}
assert(dev != NO_DEV);
#if CACHE_SANITY
assert(!find_cached_page_bydev(dev, dev_off, ino, ino_off));
#endif
hb->dev = dev;
hb->dev_offset = dev_off;
hb->ino = ino;
hb->ino_offset = ino_off;
hb->page = pb;
hb->page->refcount++; /* block also referenced by cache now */
hb->page->flags |= PBF_INCACHE;
hv_dev = makehash(dev, dev_off);
hb->hash_next_dev = cache_hash_bydev[hv_dev];
cache_hash_bydev[hv_dev] = hb;
if(hb->ino != VMC_NO_INODE)
addcache_byino(hb);
lru_add(hb);
return OK;
}
void rmcache(struct cached_page *cp)
{
struct phys_block *pb = cp->page;
int hv_dev = makehash(cp->dev, cp->dev_offset);
assert(cp->page->flags & PBF_INCACHE);
cp->page->flags &= ~PBF_INCACHE;
rmhash_bydev(cp, &cache_hash_bydev[hv_dev]);
if(cp->ino != VMC_NO_INODE) {
int hv_ino = makehash(cp->ino, cp->ino_offset);
rmhash_byino(cp, &cache_hash_byino[hv_ino]);
}
assert(cp->page->refcount >= 1);
cp->page->refcount--;
lru_rm(cp);
if(pb->refcount == 0) {
assert(pb->phys != MAP_NONE);
free_mem(ABS2CLICK(pb->phys), 1);
SLABFREE(pb);
}
SLABFREE(cp);
}
int cache_freepages(int pages)
{
struct cached_page *cp, *newercp;
int freed = 0;
int oldsteps = 0;
int skips = 0;
for(cp = lru_oldest; cp && freed < pages; cp = newercp) {
newercp = cp->newer;
assert(cp->page->refcount >= 1);
if(cp->page->refcount == 1) {
rmcache(cp);
freed++;
skips = 0;
} else skips++;
oldsteps++;
}
return freed;
}
void get_stats_info(struct vm_stats_info *vsi)
{
vsi->vsi_cached = cached_pages;
}