a89ec8bc3b
. 'anonymous' cache blocks (retrieved with NO_DEV as dev parameter) were used to implement read()s from holes in inodes that should return zeroes . this is an awkward special case in the cache code though and there's a more direct way to implement the same functionality: instead of copying from a new, anonymous, zero block, to the user target buffer, simply sys_safememset the user target buffer directly. as this was the only use of this feature, this is all that's needed to simplify the cache code a little.
692 lines
19 KiB
C
692 lines
19 KiB
C
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#define _SYSTEM
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#include <assert.h>
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#include <errno.h>
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#include <math.h>
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#include <stdlib.h>
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#include <sys/param.h>
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#include <sys/param.h>
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#include <minix/dmap.h>
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#include <minix/libminixfs.h>
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#include <minix/syslib.h>
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#include <minix/sysutil.h>
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#include <minix/u64.h>
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#include <minix/bdev.h>
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#define BP_CLEAN 0 /* on-disk block and memory copies identical */
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#define BP_DIRTY 1 /* on-disk block and memory copies differ */
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#define BUFHASH(b) ((b) % nr_bufs)
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#define MARKCLEAN lmfs_markclean
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#define MINBUFS 6 /* minimal no of bufs for sanity check */
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static struct buf *front; /* points to least recently used free block */
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static struct buf *rear; /* points to most recently used free block */
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static unsigned int bufs_in_use;/* # bufs currently in use (not on free list)*/
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static void rm_lru(struct buf *bp);
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static void read_block(struct buf *);
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static void flushall(dev_t dev);
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static int vmcache = 0; /* are we using vm's secondary cache? (initially not) */
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static struct buf *buf;
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static struct buf **buf_hash; /* the buffer hash table */
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static unsigned int nr_bufs;
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static int may_use_vmcache;
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static int fs_block_size = 1024; /* raw i/o block size */
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static int rdwt_err;
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u32_t fs_bufs_heuristic(int minbufs, u32_t btotal, u32_t bfree,
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int blocksize, dev_t majordev)
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{
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struct vm_stats_info vsi;
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int bufs;
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u32_t kbytes_used_fs, kbytes_total_fs, kbcache, kb_fsmax;
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u32_t kbytes_remain_mem, bused;
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bused = btotal-bfree;
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/* but we simply need minbufs no matter what, and we don't
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* want more than that if we're a memory device
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*/
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if(majordev == MEMORY_MAJOR) {
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return minbufs;
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}
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/* set a reasonable cache size; cache at most a certain
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* portion of the used FS, and at most a certain %age of remaining
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* memory
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*/
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if((vm_info_stats(&vsi) != OK)) {
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bufs = 1024;
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printf("fslib: heuristic info fail: default to %d bufs\n", bufs);
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return bufs;
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}
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kbytes_remain_mem = div64u(mul64u(vsi.vsi_free, vsi.vsi_pagesize), 1024);
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/* check fs usage. */
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kbytes_used_fs = div64u(mul64u(bused, blocksize), 1024);
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kbytes_total_fs = div64u(mul64u(btotal, blocksize), 1024);
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/* heuristic for a desired cache size based on FS usage;
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* but never bigger than half of the total filesystem
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*/
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kb_fsmax = sqrt_approx(kbytes_used_fs)*40;
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kb_fsmax = MIN(kb_fsmax, kbytes_total_fs/2);
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/* heuristic for a maximum usage - 10% of remaining memory */
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kbcache = MIN(kbytes_remain_mem/10, kb_fsmax);
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bufs = kbcache * 1024 / blocksize;
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/* but we simply need MINBUFS no matter what */
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if(bufs < minbufs)
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bufs = minbufs;
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return bufs;
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}
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void
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lmfs_markdirty(struct buf *bp)
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{
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bp->lmfs_dirt = BP_DIRTY;
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}
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void
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lmfs_markclean(struct buf *bp)
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{
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bp->lmfs_dirt = BP_CLEAN;
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}
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int
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lmfs_isclean(struct buf *bp)
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{
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return bp->lmfs_dirt == BP_CLEAN;
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}
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dev_t
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lmfs_dev(struct buf *bp)
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{
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return bp->lmfs_dev;
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}
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int lmfs_bytes(struct buf *bp)
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{
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return bp->lmfs_bytes;
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}
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/*===========================================================================*
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* lmfs_get_block *
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*===========================================================================*/
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struct buf *lmfs_get_block(
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register dev_t dev, /* on which device is the block? */
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register block_t block, /* which block is wanted? */
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int only_search /* if NO_READ, don't read, else act normal */
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)
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{
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/* Check to see if the requested block is in the block cache. If so, return
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* a pointer to it. If not, evict some other block and fetch it (unless
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* 'only_search' is 1). All the blocks in the cache that are not in use
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* are linked together in a chain, with 'front' pointing to the least recently
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* used block and 'rear' to the most recently used block. If 'only_search' is
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* 1, the block being requested will be overwritten in its entirety, so it is
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* only necessary to see if it is in the cache; if it is not, any free buffer
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* will do. It is not necessary to actually read the block in from disk.
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* If 'only_search' is PREFETCH, the block need not be read from the disk,
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* and the device is not to be marked on the block, so callers can tell if
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* the block returned is valid.
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* In addition to the LRU chain, there is also a hash chain to link together
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* blocks whose block numbers end with the same bit strings, for fast lookup.
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*/
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int b;
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static struct buf *bp, *prev_ptr;
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u64_t yieldid = VM_BLOCKID_NONE, getid = make64(dev, block);
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assert(buf_hash);
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assert(buf);
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assert(nr_bufs > 0);
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ASSERT(fs_block_size > 0);
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assert(dev != NO_DEV);
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/* Search the hash chain for (dev, block). Do_read() can use
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* lmfs_get_block(NO_DEV ...) to get an unnamed block to fill with zeros when
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* someone wants to read from a hole in a file, in which case this search
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* is skipped
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*/
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b = BUFHASH(block);
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bp = buf_hash[b];
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while (bp != NULL) {
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if (bp->lmfs_blocknr == block && bp->lmfs_dev == dev) {
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/* Block needed has been found. */
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if (bp->lmfs_count == 0) rm_lru(bp);
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bp->lmfs_count++; /* record that block is in use */
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ASSERT(bp->lmfs_bytes == fs_block_size);
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ASSERT(bp->lmfs_dev == dev);
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ASSERT(bp->lmfs_dev != NO_DEV);
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ASSERT(bp->data);
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return(bp);
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} else {
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/* This block is not the one sought. */
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bp = bp->lmfs_hash; /* move to next block on hash chain */
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}
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}
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/* Desired block is not on available chain. Take oldest block ('front'). */
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if ((bp = front) == NULL) panic("all buffers in use: %d", nr_bufs);
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if(bp->lmfs_bytes < fs_block_size) {
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ASSERT(!bp->data);
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ASSERT(bp->lmfs_bytes == 0);
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if(!(bp->data = alloc_contig( (size_t) fs_block_size, 0, NULL))) {
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printf("fs cache: couldn't allocate a new block.\n");
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for(bp = front;
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bp && bp->lmfs_bytes < fs_block_size; bp = bp->lmfs_next)
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;
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if(!bp) {
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panic("no buffer available");
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}
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} else {
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bp->lmfs_bytes = fs_block_size;
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}
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}
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ASSERT(bp);
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ASSERT(bp->data);
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ASSERT(bp->lmfs_bytes == fs_block_size);
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ASSERT(bp->lmfs_count == 0);
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rm_lru(bp);
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/* Remove the block that was just taken from its hash chain. */
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b = BUFHASH(bp->lmfs_blocknr);
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prev_ptr = buf_hash[b];
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if (prev_ptr == bp) {
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buf_hash[b] = bp->lmfs_hash;
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} else {
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/* The block just taken is not on the front of its hash chain. */
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while (prev_ptr->lmfs_hash != NULL)
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if (prev_ptr->lmfs_hash == bp) {
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prev_ptr->lmfs_hash = bp->lmfs_hash; /* found it */
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break;
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} else {
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prev_ptr = prev_ptr->lmfs_hash; /* keep looking */
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}
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}
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/* If the block taken is dirty, make it clean by writing it to the disk.
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* Avoid hysteresis by flushing all other dirty blocks for the same device.
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*/
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if (bp->lmfs_dev != NO_DEV) {
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if (bp->lmfs_dirt == BP_DIRTY) flushall(bp->lmfs_dev);
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/* Are we throwing out a block that contained something?
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* Give it to VM for the second-layer cache.
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*/
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yieldid = make64(bp->lmfs_dev, bp->lmfs_blocknr);
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assert(bp->lmfs_bytes == fs_block_size);
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bp->lmfs_dev = NO_DEV;
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}
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/* Fill in block's parameters and add it to the hash chain where it goes. */
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MARKCLEAN(bp); /* NO_DEV blocks may be marked dirty */
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bp->lmfs_dev = dev; /* fill in device number */
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bp->lmfs_blocknr = block; /* fill in block number */
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bp->lmfs_count++; /* record that block is being used */
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b = BUFHASH(bp->lmfs_blocknr);
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bp->lmfs_hash = buf_hash[b];
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buf_hash[b] = bp; /* add to hash list */
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assert(dev != NO_DEV);
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/* Go get the requested block unless searching or prefetching. */
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if(only_search == PREFETCH || only_search == NORMAL) {
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/* Block is not found in our cache, but we do want it
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* if it's in the vm cache.
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*/
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if(vmcache) {
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/* If we can satisfy the PREFETCH or NORMAL request
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* from the vm cache, work is done.
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*/
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if(vm_yield_block_get_block(yieldid, getid,
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bp->data, fs_block_size) == OK) {
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return bp;
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}
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}
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}
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if(only_search == PREFETCH) {
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/* PREFETCH: don't do i/o. */
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bp->lmfs_dev = NO_DEV;
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} else if (only_search == NORMAL) {
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read_block(bp);
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} else if(only_search == NO_READ) {
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/* we want this block, but its contents
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* will be overwritten. VM has to forget
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* about it.
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*/
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if(vmcache) {
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vm_forgetblock(getid);
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}
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} else
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panic("unexpected only_search value: %d", only_search);
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assert(bp->data);
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return(bp); /* return the newly acquired block */
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}
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/*===========================================================================*
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* lmfs_put_block *
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*===========================================================================*/
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void lmfs_put_block(bp, block_type)
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register struct buf *bp; /* pointer to the buffer to be released */
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int block_type; /* INODE_BLOCK, DIRECTORY_BLOCK, or whatever */
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{
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/* Return a block to the list of available blocks. Depending on 'block_type'
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* it may be put on the front or rear of the LRU chain. Blocks that are
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* expected to be needed again shortly (e.g., partially full data blocks)
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* go on the rear; blocks that are unlikely to be needed again shortly
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* (e.g., full data blocks) go on the front. Blocks whose loss can hurt
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* the integrity of the file system (e.g., inode blocks) are written to
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* disk immediately if they are dirty.
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*/
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if (bp == NULL) return; /* it is easier to check here than in caller */
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bp->lmfs_count--; /* there is one use fewer now */
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if (bp->lmfs_count != 0) return; /* block is still in use */
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bufs_in_use--; /* one fewer block buffers in use */
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/* Put this block back on the LRU chain. */
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if (bp->lmfs_dev == DEV_RAM || (block_type & ONE_SHOT)) {
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/* Block probably won't be needed quickly. Put it on front of chain.
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* It will be the next block to be evicted from the cache.
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*/
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bp->lmfs_prev = NULL;
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bp->lmfs_next = front;
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if (front == NULL)
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rear = bp; /* LRU chain was empty */
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else
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front->lmfs_prev = bp;
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front = bp;
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}
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else {
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/* Block probably will be needed quickly. Put it on rear of chain.
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* It will not be evicted from the cache for a long time.
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*/
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bp->lmfs_prev = rear;
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bp->lmfs_next = NULL;
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if (rear == NULL)
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front = bp;
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else
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rear->lmfs_next = bp;
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rear = bp;
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}
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}
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/*===========================================================================*
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* read_block *
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*===========================================================================*/
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static void read_block(bp)
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register struct buf *bp; /* buffer pointer */
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{
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/* Read or write a disk block. This is the only routine in which actual disk
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* I/O is invoked. If an error occurs, a message is printed here, but the error
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* is not reported to the caller. If the error occurred while purging a block
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* from the cache, it is not clear what the caller could do about it anyway.
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*/
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int r, op_failed;
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u64_t pos;
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dev_t dev = bp->lmfs_dev;
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op_failed = 0;
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assert(dev != NO_DEV);
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pos = mul64u(bp->lmfs_blocknr, fs_block_size);
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r = bdev_read(dev, pos, bp->data, fs_block_size,
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BDEV_NOFLAGS);
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if (r < 0) {
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printf("fs cache: I/O error on device %d/%d, block %u\n",
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major(dev), minor(dev), bp->lmfs_blocknr);
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op_failed = 1;
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} else if (r != (ssize_t) fs_block_size) {
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r = END_OF_FILE;
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op_failed = 1;
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}
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if (op_failed) {
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bp->lmfs_dev = NO_DEV; /* invalidate block */
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/* Report read errors to interested parties. */
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rdwt_err = r;
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}
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}
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/*===========================================================================*
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* lmfs_invalidate *
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*===========================================================================*/
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void lmfs_invalidate(
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dev_t device /* device whose blocks are to be purged */
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)
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{
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/* Remove all the blocks belonging to some device from the cache. */
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register struct buf *bp;
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for (bp = &buf[0]; bp < &buf[nr_bufs]; bp++)
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if (bp->lmfs_dev == device) bp->lmfs_dev = NO_DEV;
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vm_forgetblocks();
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}
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/*===========================================================================*
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* flushall *
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*===========================================================================*/
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static void flushall(dev_t dev)
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{
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/* Flush all dirty blocks for one device. */
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register struct buf *bp;
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static struct buf **dirty; /* static so it isn't on stack */
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static unsigned int dirtylistsize = 0;
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int ndirty;
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if(dirtylistsize != nr_bufs) {
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if(dirtylistsize > 0) {
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assert(dirty != NULL);
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free(dirty);
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}
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if(!(dirty = malloc(sizeof(dirty[0])*nr_bufs)))
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panic("couldn't allocate dirty buf list");
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dirtylistsize = nr_bufs;
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}
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for (bp = &buf[0], ndirty = 0; bp < &buf[nr_bufs]; bp++) {
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if (bp->lmfs_dirt == BP_DIRTY && bp->lmfs_dev == dev) {
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dirty[ndirty++] = bp;
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}
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}
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lmfs_rw_scattered(dev, dirty, ndirty, WRITING);
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}
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/*===========================================================================*
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* lmfs_rw_scattered *
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*===========================================================================*/
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void lmfs_rw_scattered(
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dev_t dev, /* major-minor device number */
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struct buf **bufq, /* pointer to array of buffers */
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int bufqsize, /* number of buffers */
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int rw_flag /* READING or WRITING */
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)
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{
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/* Read or write scattered data from a device. */
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register struct buf *bp;
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int gap;
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register int i;
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register iovec_t *iop;
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static iovec_t *iovec = NULL;
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u64_t pos;
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int j, r;
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STATICINIT(iovec, NR_IOREQS);
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/* (Shell) sort buffers on lmfs_blocknr. */
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gap = 1;
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do
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gap = 3 * gap + 1;
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while (gap <= bufqsize);
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while (gap != 1) {
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gap /= 3;
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for (j = gap; j < bufqsize; j++) {
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for (i = j - gap;
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i >= 0 && bufq[i]->lmfs_blocknr > bufq[i + gap]->lmfs_blocknr;
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i -= gap) {
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bp = bufq[i];
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bufq[i] = bufq[i + gap];
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bufq[i + gap] = bp;
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}
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}
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}
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/* Set up I/O vector and do I/O. The result of bdev I/O is OK if everything
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* went fine, otherwise the error code for the first failed transfer.
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*/
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while (bufqsize > 0) {
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for (j = 0, iop = iovec; j < NR_IOREQS && j < bufqsize; j++, iop++) {
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bp = bufq[j];
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if (bp->lmfs_blocknr != (block_t) bufq[0]->lmfs_blocknr + j) break;
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iop->iov_addr = (vir_bytes) bp->data;
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iop->iov_size = (vir_bytes) fs_block_size;
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}
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pos = mul64u(bufq[0]->lmfs_blocknr, fs_block_size);
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if (rw_flag == READING)
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r = bdev_gather(dev, pos, iovec, j, BDEV_NOFLAGS);
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else
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r = bdev_scatter(dev, pos, iovec, j, BDEV_NOFLAGS);
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/* Harvest the results. The driver may have returned an error, or it
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* may have done less than what we asked for.
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*/
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if (r < 0) {
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printf("fs cache: I/O error %d on device %d/%d, block %u\n",
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r, major(dev), minor(dev), bufq[0]->lmfs_blocknr);
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}
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for (i = 0; i < j; i++) {
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bp = bufq[i];
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if (r < (ssize_t) fs_block_size) {
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/* Transfer failed. */
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if (i == 0) {
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bp->lmfs_dev = NO_DEV; /* Invalidate block */
|
|
vm_forgetblocks();
|
|
}
|
|
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 += i;
|
|
bufqsize -= i;
|
|
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;
|
|
|
|
bufs_in_use++;
|
|
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;
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* lmfs_set_blocksize *
|
|
*===========================================================================*/
|
|
void lmfs_set_blocksize(int new_block_size, int major)
|
|
{
|
|
int bufs;
|
|
u32_t btotal, bfree, bused;
|
|
|
|
cache_resize(new_block_size, MINBUFS);
|
|
|
|
fs_blockstats(&btotal, &bfree, &bused);
|
|
|
|
bufs = fs_bufs_heuristic(10, btotal, bfree,
|
|
new_block_size, major);
|
|
|
|
cache_resize(new_block_size, bufs);
|
|
|
|
/* 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(vm_forgetblock(VM_BLOCKID_NONE) != ENOSYS &&
|
|
may_use_vmcache && major != MEMORY_MAJOR) {
|
|
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);
|
|
free_contig(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;
|
|
|
|
vm_forgetblocks();
|
|
}
|
|
|
|
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 && bp->lmfs_dirt == BP_DIRTY)
|
|
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;
|
|
}
|