minix/lib/libminixfs/cache.c
Ben Gras f0cc010614 libminixfs, mfs, ext2: may re-evaluate cache size
libminixfs may now be informed of changes to the block usage on the
filesystem. if the net change becomes big enough, libminixfs may
resize the cache based on the new usage.

	. update the 2 FSes to provide this information to libminixfs

Change-Id: I158815a11da801fd5572a8de89c9e6c039b82650
2013-04-26 13:57:08 +00:00

930 lines
24 KiB
C

#define _SYSTEM
#include <assert.h>
#include <errno.h>
#include <math.h>
#include <stdlib.h>
#include <sys/param.h>
#include <sys/mman.h>
#include <minix/dmap.h>
#include <minix/libminixfs.h>
#include <minix/syslib.h>
#include <minix/sysutil.h>
#include <minix/u64.h>
#include <minix/bdev.h>
#define BUFHASH(b) ((b) % nr_bufs)
#define MARKCLEAN lmfs_markclean
#define MINBUFS 6 /* minimal no of bufs for sanity check */
static struct buf *front; /* points to least recently used free block */
static struct buf *rear; /* points to most recently used free block */
static unsigned int bufs_in_use;/* # bufs currently in use (not on free list)*/
static void rm_lru(struct buf *bp);
static void read_block(struct buf *);
static void flushall(dev_t dev);
static void freeblock(struct buf *bp);
static void cache_heuristic_check(int major);
static int vmcache = 0; /* are we using vm's secondary cache? (initially not) */
static struct buf *buf;
static struct buf **buf_hash; /* the buffer hash table */
static unsigned int nr_bufs;
static int may_use_vmcache;
static int fs_block_size = 1024; /* raw i/o block size */
static int rdwt_err;
static int quiet = 0;
void
lmfs_setquiet(int q) { quiet = q; }
u32_t fs_bufs_heuristic(int minbufs, u32_t btotal, u32_t bfree,
int blocksize, dev_t majordev)
{
struct vm_stats_info vsi;
int bufs;
u32_t kbytes_used_fs, kbytes_total_fs, kbcache, kb_fsmax;
u32_t kbytes_remain_mem, bused;
bused = btotal-bfree;
/* set a reasonable cache size; cache at most a certain
* portion of the used FS, and at most a certain %age of remaining
* memory
*/
if(vm_info_stats(&vsi) != OK) {
bufs = 1024;
if(!quiet)
printf("fslib: heuristic info fail: default to %d bufs\n", bufs);
return bufs;
}
/* remaining free memory is unused memory plus memory in used for cache,
* as the cache can be evicted
*/
kbytes_remain_mem = (u64_t)(vsi.vsi_free + vsi.vsi_cached) *
vsi.vsi_pagesize / 1024;
/* check fs usage. */
kbytes_used_fs = div64u(mul64u(bused, blocksize), 1024);
kbytes_total_fs = div64u(mul64u(btotal, blocksize), 1024);
/* heuristic for a desired cache size based on FS usage;
* but never bigger than half of the total filesystem
*/
kb_fsmax = sqrt_approx(kbytes_used_fs)*40;
kb_fsmax = MIN(kb_fsmax, kbytes_total_fs/2);
/* heuristic for a maximum usage - 10% of remaining memory */
kbcache = MIN(kbytes_remain_mem/10, kb_fsmax);
bufs = kbcache * 1024 / blocksize;
/* but we simply need MINBUFS no matter what */
if(bufs < minbufs)
bufs = minbufs;
return bufs;
}
void lmfs_blockschange(dev_t dev, int delta)
{
/* Change the number of allocated blocks by 'delta.'
* Also accumulate the delta since the last cache re-evaluation.
* If it is outside a certain band, ask the cache library to
* re-evaluate the cache size.
*/
static int bitdelta = 0;
bitdelta += delta;
#define BANDKB (10*1024) /* recheck cache every 10MB change */
if(bitdelta*fs_block_size/1024 > BANDKB ||
bitdelta*fs_block_size/1024 < -BANDKB) {
lmfs_cache_reevaluate(dev);
bitdelta = 0;
}
}
void
lmfs_markdirty(struct buf *bp)
{
bp->lmfs_flags |= VMMC_DIRTY;
}
void
lmfs_markclean(struct buf *bp)
{
bp->lmfs_flags &= ~VMMC_DIRTY;
}
int
lmfs_isclean(struct buf *bp)
{
return !(bp->lmfs_flags & VMMC_DIRTY);
}
dev_t
lmfs_dev(struct buf *bp)
{
return bp->lmfs_dev;
}
int lmfs_bytes(struct buf *bp)
{
return bp->lmfs_bytes;
}
static void
free_unused_blocks(void)
{
struct buf *bp;
int freed = 0, bytes = 0;
printf("libminixfs: freeing; %d blocks in use\n", bufs_in_use);
for(bp = &buf[0]; bp < &buf[nr_bufs]; bp++) {
if(bp->lmfs_bytes > 0 && bp->lmfs_count == 0) {
freed++;
bytes += bp->lmfs_bytes;
freeblock(bp);
}
}
printf("libminixfs: freeing; %d blocks, %d bytes\n", freed, bytes);
}
static void
lmfs_alloc_block(struct buf *bp)
{
ASSERT(!bp->data);
ASSERT(bp->lmfs_bytes == 0);
ASSERT(!(fs_block_size % PAGE_SIZE));
if((bp->data = minix_mmap(0, fs_block_size,
PROT_READ|PROT_WRITE, MAP_PREALLOC|MAP_ANON, -1, 0)) == MAP_FAILED) {
free_unused_blocks();
if((bp->data = minix_mmap(0, fs_block_size, PROT_READ|PROT_WRITE,
MAP_PREALLOC|MAP_ANON, -1, 0)) == MAP_FAILED) {
panic("libminixfs: could not allocate block");
}
}
assert(bp->data);
bp->lmfs_bytes = fs_block_size;
bp->lmfs_needsetcache = 1;
}
/*===========================================================================*
* lmfs_get_block *
*===========================================================================*/
struct buf *lmfs_get_block(register dev_t dev, register block_t block,
int only_search)
{
return lmfs_get_block_ino(dev, block, only_search, VMC_NO_INODE, 0);
}
void minix_munmap_t(void *a, int len)
{
vir_bytes av = (vir_bytes) a;
assert(a);
assert(a != MAP_FAILED);
assert(len > 0);
assert(!(len % PAGE_SIZE));
assert(!(av % PAGE_SIZE));
if(minix_munmap(a, len) < 0)
panic("libminixfs cache: munmap failed");
}
static void raisecount(struct buf *bp)
{
assert(bufs_in_use >= 0);
ASSERT(bp->lmfs_count >= 0);
bp->lmfs_count++;
if(bp->lmfs_count == 1) bufs_in_use++;
assert(bufs_in_use > 0);
}
static void lowercount(struct buf *bp)
{
assert(bufs_in_use > 0);
ASSERT(bp->lmfs_count > 0);
bp->lmfs_count--;
if(bp->lmfs_count == 0) bufs_in_use--;
assert(bufs_in_use >= 0);
}
static void freeblock(struct buf *bp)
{
ASSERT(bp->lmfs_count == 0);
/* If the block taken is dirty, make it clean by writing it to the disk.
* Avoid hysteresis by flushing all other dirty blocks for the same device.
*/
if (bp->lmfs_dev != NO_DEV) {
if (!lmfs_isclean(bp)) flushall(bp->lmfs_dev);
assert(bp->lmfs_bytes == fs_block_size);
bp->lmfs_dev = NO_DEV;
}
/* Fill in block's parameters and add it to the hash chain where it goes. */
MARKCLEAN(bp); /* NO_DEV blocks may be marked dirty */
if(bp->lmfs_bytes > 0) {
assert(bp->data);
minix_munmap_t(bp->data, bp->lmfs_bytes);
bp->lmfs_bytes = 0;
bp->data = NULL;
} else assert(!bp->data);
}
/*===========================================================================*
* lmfs_get_block_ino *
*===========================================================================*/
struct buf *lmfs_get_block_ino(dev_t dev, block_t block, int only_search,
ino_t ino, u64_t ino_off)
{
/* Check to see if the requested block is in the block cache. If so, return
* a pointer to it. If not, evict some other block and fetch it (unless
* 'only_search' is 1). All the blocks in the cache that are not in use
* are linked together in a chain, with 'front' pointing to the least recently
* used block and 'rear' to the most recently used block. If 'only_search' is
* 1, the block being requested will be overwritten in its entirety, so it is
* only necessary to see if it is in the cache; if it is not, any free buffer
* will do. It is not necessary to actually read the block in from disk.
* If 'only_search' is PREFETCH, the block need not be read from the disk,
* and the device is not to be marked on the block, so callers can tell if
* the block returned is valid.
* In addition to the LRU chain, there is also a hash chain to link together
* blocks whose block numbers end with the same bit strings, for fast lookup.
*/
int b;
static struct buf *bp;
u64_t dev_off = (u64_t) block * fs_block_size;
struct buf *prev_ptr;
assert(buf_hash);
assert(buf);
assert(nr_bufs > 0);
ASSERT(fs_block_size > 0);
assert(dev != NO_DEV);
if((ino_off % fs_block_size)) {
printf("cache: unaligned lmfs_get_block_ino ino_off %llu\n",
ino_off);
util_stacktrace();
}
/* Search the hash chain for (dev, block). */
b = BUFHASH(block);
bp = buf_hash[b];
while (bp != NULL) {
if (bp->lmfs_blocknr == block && bp->lmfs_dev == dev) {
if(bp->lmfs_flags & VMMC_EVICTED) {
/* We had it but VM evicted it; invalidate it. */
ASSERT(bp->lmfs_count == 0);
ASSERT(!(bp->lmfs_flags & VMMC_BLOCK_LOCKED));
ASSERT(!(bp->lmfs_flags & VMMC_DIRTY));
bp->lmfs_dev = NO_DEV;
bp->lmfs_bytes = 0;
bp->data = NULL;
break;
}
ASSERT(bp->lmfs_needsetcache == 0);
/* Block needed has been found. */
if (bp->lmfs_count == 0) {
rm_lru(bp);
ASSERT(!(bp->lmfs_flags & VMMC_BLOCK_LOCKED));
bp->lmfs_flags |= VMMC_BLOCK_LOCKED;
}
raisecount(bp);
ASSERT(bp->lmfs_bytes == fs_block_size);
ASSERT(bp->lmfs_dev == dev);
ASSERT(bp->lmfs_dev != NO_DEV);
ASSERT(bp->lmfs_flags & VMMC_BLOCK_LOCKED);
ASSERT(bp->data);
if(ino != VMC_NO_INODE) {
if(bp->lmfs_inode == VMC_NO_INODE
|| bp->lmfs_inode != ino
|| bp->lmfs_inode_offset != ino_off) {
bp->lmfs_inode = ino;
bp->lmfs_inode_offset = ino_off;
bp->lmfs_needsetcache = 1;
}
}
return(bp);
} else {
/* This block is not the one sought. */
bp = bp->lmfs_hash; /* move to next block on hash chain */
}
}
/* Desired block is not on available chain. Find a free block to use. */
if(bp) {
ASSERT(bp->lmfs_flags & VMMC_EVICTED);
} else {
if ((bp = front) == NULL) panic("all buffers in use: %d", nr_bufs);
}
assert(bp);
rm_lru(bp);
/* Remove the block that was just taken from its hash chain. */
b = BUFHASH(bp->lmfs_blocknr);
prev_ptr = buf_hash[b];
if (prev_ptr == bp) {
buf_hash[b] = bp->lmfs_hash;
} else {
/* The block just taken is not on the front of its hash chain. */
while (prev_ptr->lmfs_hash != NULL)
if (prev_ptr->lmfs_hash == bp) {
prev_ptr->lmfs_hash = bp->lmfs_hash; /* found it */
break;
} else {
prev_ptr = prev_ptr->lmfs_hash; /* keep looking */
}
}
freeblock(bp);
bp->lmfs_inode = ino;
bp->lmfs_inode_offset = ino_off;
bp->lmfs_flags = VMMC_BLOCK_LOCKED;
bp->lmfs_needsetcache = 0;
bp->lmfs_dev = dev; /* fill in device number */
bp->lmfs_blocknr = block; /* fill in block number */
ASSERT(bp->lmfs_count == 0);
raisecount(bp);
b = BUFHASH(bp->lmfs_blocknr);
bp->lmfs_hash = buf_hash[b];
buf_hash[b] = bp; /* add to hash list */
assert(dev != NO_DEV);
/* Block is not found in our cache, but we do want it
* if it's in the vm cache.
*/
assert(!bp->data);
assert(!bp->lmfs_bytes);
if(vmcache) {
if((bp->data = vm_map_cacheblock(dev, dev_off, ino, ino_off,
&bp->lmfs_flags, fs_block_size)) != MAP_FAILED) {
bp->lmfs_bytes = fs_block_size;
ASSERT(!bp->lmfs_needsetcache);
return bp;
}
}
bp->data = NULL;
/* Not in the cache; reserve memory for its contents. */
lmfs_alloc_block(bp);
assert(bp->data);
if(only_search == PREFETCH) {
/* PREFETCH: don't do i/o. */
bp->lmfs_dev = NO_DEV;
} else if (only_search == NORMAL) {
read_block(bp);
} else if(only_search == NO_READ) {
/* This block will be overwritten by new contents. */
} else
panic("unexpected only_search value: %d", only_search);
assert(bp->data);
return(bp); /* return the newly acquired block */
}
/*===========================================================================*
* lmfs_put_block *
*===========================================================================*/
void lmfs_put_block(bp, block_type)
register struct buf *bp; /* pointer to the buffer to be released */
int block_type; /* INODE_BLOCK, DIRECTORY_BLOCK, or whatever */
{
/* Return a block to the list of available blocks. Depending on 'block_type'
* it may be put on the front or rear of the LRU chain. Blocks that are
* expected to be needed again shortly (e.g., partially full data blocks)
* go on the rear; blocks that are unlikely to be needed again shortly
* (e.g., full data blocks) go on the front. Blocks whose loss can hurt
* the integrity of the file system (e.g., inode blocks) are written to
* disk immediately if they are dirty.
*/
dev_t dev;
u64_t dev_off;
int r;
if (bp == NULL) return; /* it is easier to check here than in caller */
dev = bp->lmfs_dev;
dev_off = (u64_t) bp->lmfs_blocknr * fs_block_size;
lowercount(bp);
if (bp->lmfs_count != 0) return; /* block is still in use */
/* Put this block back on the LRU chain. */
if (dev == DEV_RAM || (block_type & ONE_SHOT)) {
/* Block probably won't be needed quickly. Put it on front of chain.
* It will be the next block to be evicted from the cache.
*/
bp->lmfs_prev = NULL;
bp->lmfs_next = front;
if (front == NULL)
rear = bp; /* LRU chain was empty */
else
front->lmfs_prev = bp;
front = bp;
}
else {
/* Block probably will be needed quickly. Put it on rear of chain.
* It will not be evicted from the cache for a long time.
*/
bp->lmfs_prev = rear;
bp->lmfs_next = NULL;
if (rear == NULL)
front = bp;
else
rear->lmfs_next = bp;
rear = bp;
}
assert(bp->lmfs_flags & VMMC_BLOCK_LOCKED);
bp->lmfs_flags &= ~VMMC_BLOCK_LOCKED;
/* block has sensible content - if necesary, identify it to VM */
if(vmcache && bp->lmfs_needsetcache && dev != NO_DEV) {
if((r=vm_set_cacheblock(bp->data, dev, dev_off,
bp->lmfs_inode, bp->lmfs_inode_offset,
&bp->lmfs_flags, fs_block_size)) != OK) {
if(r == ENOSYS) {
printf("libminixfs: ENOSYS, disabling VM calls\n");
vmcache = 0;
} else {
panic("libminixfs: setblock of 0x%lx dev 0x%x off "
"0x%llx failed\n", bp->data, dev, dev_off);
}
}
}
bp->lmfs_needsetcache = 0;
}
void lmfs_cache_reevaluate(dev_t dev)
{
if(bufs_in_use == 0 && dev != NO_DEV) {
/* if the cache isn't in use any more, we could resize it. */
cache_heuristic_check(major(dev));
}
}
/*===========================================================================*
* read_block *
*===========================================================================*/
static void read_block(bp)
register struct buf *bp; /* buffer pointer */
{
/* Read or write a disk block. This is the only routine in which actual disk
* I/O is invoked. If an error occurs, a message is printed here, but the error
* is not reported to the caller. If the error occurred while purging a block
* from the cache, it is not clear what the caller could do about it anyway.
*/
int r, op_failed;
u64_t pos;
dev_t dev = bp->lmfs_dev;
op_failed = 0;
assert(dev != NO_DEV);
ASSERT(bp->lmfs_bytes == fs_block_size);
ASSERT(fs_block_size > 0);
ASSERT(!(fs_block_size % PAGE_SIZE));
pos = mul64u(bp->lmfs_blocknr, fs_block_size);
if(fs_block_size > PAGE_SIZE) {
#define MAXPAGES 20
vir_bytes vaddr = (vir_bytes) bp->data;
int p;
static iovec_t iovec[MAXPAGES];
int pages = fs_block_size/PAGE_SIZE;
ASSERT(pages > 1 && pages < MAXPAGES);
for(p = 0; p < pages; p++) {
iovec[p].iov_addr = vaddr;
iovec[p].iov_size = PAGE_SIZE;
vaddr += PAGE_SIZE;
}
r = bdev_gather(dev, pos, iovec, pages, BDEV_NOFLAGS);
} else {
r = bdev_read(dev, pos, bp->data, fs_block_size,
BDEV_NOFLAGS);
}
if (r < 0) {
printf("fs cache: I/O error on device %d/%d, block %u\n",
major(dev), minor(dev), bp->lmfs_blocknr);
op_failed = 1;
} else if (r != (ssize_t) fs_block_size) {
r = END_OF_FILE;
op_failed = 1;
}
if (op_failed) {
bp->lmfs_dev = NO_DEV; /* invalidate block */
/* Report read errors to interested parties. */
rdwt_err = r;
}
}
/*===========================================================================*
* lmfs_invalidate *
*===========================================================================*/
void lmfs_invalidate(
dev_t device /* device whose blocks are to be purged */
)
{
/* Remove all the blocks belonging to some device from the cache. */
register struct buf *bp;
for (bp = &buf[0]; bp < &buf[nr_bufs]; bp++) {
if (bp->lmfs_dev == device) {
assert(bp->data);
assert(bp->lmfs_bytes > 0);
minix_munmap_t(bp->data, bp->lmfs_bytes);
bp->lmfs_dev = NO_DEV;
bp->lmfs_bytes = 0;
bp->data = NULL;
}
}
}
/*===========================================================================*
* flushall *
*===========================================================================*/
static void flushall(dev_t dev)
{
/* Flush all dirty blocks for one device. */
register struct buf *bp;
static struct buf **dirty; /* static so it isn't on stack */
static unsigned int dirtylistsize = 0;
int ndirty;
if(dirtylistsize != nr_bufs) {
if(dirtylistsize > 0) {
assert(dirty != NULL);
free(dirty);
}
if(!(dirty = malloc(sizeof(dirty[0])*nr_bufs)))
panic("couldn't allocate dirty buf list");
dirtylistsize = nr_bufs;
}
for (bp = &buf[0], ndirty = 0; bp < &buf[nr_bufs]; bp++) {
if (!lmfs_isclean(bp) && bp->lmfs_dev == dev) {
dirty[ndirty++] = bp;
}
}
lmfs_rw_scattered(dev, dirty, ndirty, WRITING);
}
/*===========================================================================*
* lmfs_rw_scattered *
*===========================================================================*/
void lmfs_rw_scattered(
dev_t dev, /* major-minor device number */
struct buf **bufq, /* pointer to array of buffers */
int bufqsize, /* number of buffers */
int rw_flag /* READING or WRITING */
)
{
/* Read or write scattered data from a device. */
register struct buf *bp;
int gap;
register int i;
register iovec_t *iop;
static iovec_t *iovec = NULL;
u64_t pos;
int iov_per_block;
STATICINIT(iovec, NR_IOREQS);
assert(dev != NO_DEV);
assert(!(fs_block_size % PAGE_SIZE));
assert(fs_block_size > 0);
iov_per_block = fs_block_size / PAGE_SIZE;
/* (Shell) sort buffers on lmfs_blocknr. */
gap = 1;
do
gap = 3 * gap + 1;
while (gap <= bufqsize);
while (gap != 1) {
int j;
gap /= 3;
for (j = gap; j < bufqsize; j++) {
for (i = j - gap;
i >= 0 && bufq[i]->lmfs_blocknr > bufq[i + gap]->lmfs_blocknr;
i -= gap) {
bp = bufq[i];
bufq[i] = bufq[i + gap];
bufq[i + gap] = bp;
}
}
}
/* Set up I/O vector and do I/O. The result of bdev I/O is OK if everything
* went fine, otherwise the error code for the first failed transfer.
*/
while (bufqsize > 0) {
int nblocks = 0, niovecs = 0;
int r;
for (iop = iovec; nblocks < bufqsize; nblocks++) {
int p;
vir_bytes vdata;
bp = bufq[nblocks];
if (bp->lmfs_blocknr != (block_t) bufq[0]->lmfs_blocknr + nblocks)
break;
if(niovecs >= NR_IOREQS-iov_per_block) break;
vdata = (vir_bytes) bp->data;
for(p = 0; p < iov_per_block; p++) {
iop->iov_addr = vdata;
iop->iov_size = PAGE_SIZE;
vdata += PAGE_SIZE;
iop++;
niovecs++;
}
}
assert(nblocks > 0);
assert(niovecs > 0);
pos = mul64u(bufq[0]->lmfs_blocknr, fs_block_size);
if (rw_flag == READING)
r = bdev_gather(dev, pos, iovec, niovecs, BDEV_NOFLAGS);
else
r = bdev_scatter(dev, pos, iovec, niovecs, BDEV_NOFLAGS);
/* Harvest the results. The driver may have returned an error, or it
* may have done less than what we asked for.
*/
if (r < 0) {
printf("fs cache: I/O error %d on device %d/%d, block %u\n",
r, major(dev), minor(dev), bufq[0]->lmfs_blocknr);
}
for (i = 0; i < nblocks; i++) {
bp = bufq[i];
if (r < (ssize_t) fs_block_size) {
/* Transfer failed. */
if (i == 0) {
bp->lmfs_dev = NO_DEV; /* Invalidate block */
}
break;
}
if (rw_flag == READING) {
bp->lmfs_dev = dev; /* validate block */
lmfs_put_block(bp, PARTIAL_DATA_BLOCK);
} else {
MARKCLEAN(bp);
}
r -= fs_block_size;
}
bufq += nblocks;
bufqsize -= nblocks;
if (rw_flag == READING) {
/* Don't bother reading more than the device is willing to
* give at this time. Don't forget to release those extras.
*/
while (bufqsize > 0) {
lmfs_put_block(*bufq++, PARTIAL_DATA_BLOCK);
bufqsize--;
}
}
if (rw_flag == WRITING && i == 0) {
/* We're not making progress, this means we might keep
* looping. Buffers remain dirty if un-written. Buffers are
* lost if invalidate()d or LRU-removed while dirty. This
* is better than keeping unwritable blocks around forever..
*/
break;
}
}
}
/*===========================================================================*
* rm_lru *
*===========================================================================*/
static void rm_lru(bp)
struct buf *bp;
{
/* Remove a block from its LRU chain. */
struct buf *next_ptr, *prev_ptr;
next_ptr = bp->lmfs_next; /* successor on LRU chain */
prev_ptr = bp->lmfs_prev; /* predecessor on LRU chain */
if (prev_ptr != NULL)
prev_ptr->lmfs_next = next_ptr;
else
front = next_ptr; /* this block was at front of chain */
if (next_ptr != NULL)
next_ptr->lmfs_prev = prev_ptr;
else
rear = prev_ptr; /* this block was at rear of chain */
}
/*===========================================================================*
* cache_resize *
*===========================================================================*/
static void cache_resize(unsigned int blocksize, unsigned int bufs)
{
struct buf *bp;
assert(blocksize > 0);
assert(bufs >= MINBUFS);
for (bp = &buf[0]; bp < &buf[nr_bufs]; bp++)
if(bp->lmfs_count != 0) panic("change blocksize with buffer in use");
lmfs_buf_pool(bufs);
fs_block_size = blocksize;
}
static void cache_heuristic_check(int major)
{
int bufs, d;
u32_t btotal, bfree, bused;
fs_blockstats(&btotal, &bfree, &bused);
bufs = fs_bufs_heuristic(10, btotal, bfree,
fs_block_size, major);
/* set the cache to the new heuristic size if the new one
* is more than 10% off from the current one.
*/
d = bufs-nr_bufs;
if(d < 0) d = -d;
if(d*100/nr_bufs > 10) {
cache_resize(fs_block_size, bufs);
}
}
/*===========================================================================*
* lmfs_set_blocksize *
*===========================================================================*/
void lmfs_set_blocksize(int new_block_size, int major)
{
cache_resize(new_block_size, MINBUFS);
cache_heuristic_check(major);
/* Decide whether to use seconday cache or not.
* Only do this if
* - it's available, and
* - use of it hasn't been disabled for this fs, and
* - our main FS device isn't a memory device
*/
vmcache = 0;
if(may_use_vmcache)
vmcache = 1;
}
/*===========================================================================*
* lmfs_buf_pool *
*===========================================================================*/
void lmfs_buf_pool(int new_nr_bufs)
{
/* Initialize the buffer pool. */
register struct buf *bp;
assert(new_nr_bufs >= MINBUFS);
if(nr_bufs > 0) {
assert(buf);
(void) fs_sync();
for (bp = &buf[0]; bp < &buf[nr_bufs]; bp++) {
if(bp->data) {
assert(bp->lmfs_bytes > 0);
minix_munmap_t(bp->data, bp->lmfs_bytes);
}
}
}
if(buf)
free(buf);
if(!(buf = calloc(sizeof(buf[0]), new_nr_bufs)))
panic("couldn't allocate buf list (%d)", new_nr_bufs);
if(buf_hash)
free(buf_hash);
if(!(buf_hash = calloc(sizeof(buf_hash[0]), new_nr_bufs)))
panic("couldn't allocate buf hash list (%d)", new_nr_bufs);
nr_bufs = new_nr_bufs;
bufs_in_use = 0;
front = &buf[0];
rear = &buf[nr_bufs - 1];
for (bp = &buf[0]; bp < &buf[nr_bufs]; bp++) {
bp->lmfs_blocknr = NO_BLOCK;
bp->lmfs_dev = NO_DEV;
bp->lmfs_next = bp + 1;
bp->lmfs_prev = bp - 1;
bp->data = NULL;
bp->lmfs_bytes = 0;
}
front->lmfs_prev = NULL;
rear->lmfs_next = NULL;
for (bp = &buf[0]; bp < &buf[nr_bufs]; bp++) bp->lmfs_hash = bp->lmfs_next;
buf_hash[0] = front;
}
int lmfs_bufs_in_use(void)
{
return bufs_in_use;
}
int lmfs_nr_bufs(void)
{
return nr_bufs;
}
void lmfs_flushall(void)
{
struct buf *bp;
for(bp = &buf[0]; bp < &buf[nr_bufs]; bp++)
if(bp->lmfs_dev != NO_DEV && !lmfs_isclean(bp))
flushall(bp->lmfs_dev);
}
int lmfs_fs_block_size(void)
{
return fs_block_size;
}
void lmfs_may_use_vmcache(int ok)
{
may_use_vmcache = ok;
}
void lmfs_reset_rdwt_err(void)
{
rdwt_err = OK;
}
int lmfs_rdwt_err(void)
{
return rdwt_err;
}
int lmfs_do_bpeek(message *m)
{
block_t startblock, b, limitblock;
dev_t dev = m->REQ_DEV2;
u64_t extra, pos = make64(m->REQ_SEEK_POS_LO, m->REQ_SEEK_POS_HI);
size_t len = m->REQ_NBYTES;
struct buf *bp;
assert(m->m_type == REQ_BPEEK);
assert(fs_block_size > 0);
assert(dev != NO_DEV);
if((extra=(pos % fs_block_size))) {
pos -= extra;
len += extra;
}
len = roundup(len, fs_block_size);
startblock = pos/fs_block_size;
limitblock = startblock + len/fs_block_size;
for(b = startblock; b < limitblock; b++) {
bp = lmfs_get_block(dev, b, NORMAL);
assert(bp);
lmfs_put_block(bp, FULL_DATA_BLOCK);
}
return OK;
}