ref: 3d5dca521797b5a91ebc4281fbaf58211bb4f40f
dir: /sys/src/cmd/ext4srv/ext4_bcache.c/
#include "ext4_config.h"
#include "ext4_types.h"
#include "ext4_bcache.h"
#include "ext4_blockdev.h"
#include "ext4_debug.h"
static int ext4_bcache_lba_compare(struct ext4_buf *a, struct ext4_buf *b)
{
if (a->lba > b->lba)
return 1;
else if (a->lba < b->lba)
return -1;
return 0;
}
static int ext4_bcache_lru_compare(struct ext4_buf *a, struct ext4_buf *b)
{
if (a->lru_id > b->lru_id)
return 1;
else if (a->lru_id < b->lru_id)
return -1;
return 0;
}
RB_GENERATE_INTERNAL(ext4_buf_lba, ext4_buf, lba_node,
ext4_bcache_lba_compare, static inline)
RB_GENERATE_INTERNAL(ext4_buf_lru, ext4_buf, lru_node,
ext4_bcache_lru_compare, static inline)
int ext4_bcache_init_dynamic(struct ext4_bcache *bc, u32int cnt,
u32int itemsize)
{
assert(bc && cnt && itemsize);
memset(bc, 0, sizeof(struct ext4_bcache));
bc->cnt = cnt;
bc->itemsize = itemsize;
bc->ref_blocks = 0;
bc->max_ref_blocks = 0;
return 0;
}
void ext4_bcache_cleanup(struct ext4_bcache *bc)
{
struct ext4_buf *buf, *tmp;
RB_FOREACH_SAFE(buf, ext4_buf_lba, &bc->lba_root, tmp) {
ext4_block_flush_buf(bc->bdev, buf);
ext4_bcache_drop_buf(bc, buf);
}
}
int ext4_bcache_fini_dynamic(struct ext4_bcache *bc)
{
memset(bc, 0, sizeof(struct ext4_bcache));
return 0;
}
/**@brief:
*
* This is ext4_bcache, the module handling basic buffer-cache stuff.
*
* Buffers in a bcache are sorted by their LBA and stored in a
* RB-Tree(lba_root).
*
* Bcache also maintains another RB-Tree(lru_root) right now, where
* buffers are sorted by their LRU id.
*
* A singly-linked list is used to track those dirty buffers which are
* ready to be flushed. (Those buffers which are dirty but also referenced
* are not considered ready to be flushed.)
*
* When a buffer is not referenced, it will be stored in both lba_root
* and lru_root, while it will only be stored in lba_root when it is
* referenced.
*/
static struct ext4_buf *
ext4_buf_alloc(struct ext4_bcache *bc, u64int lba)
{
void *data;
struct ext4_buf *buf;
data = ext4_malloc(bc->itemsize);
if (!data)
return nil;
buf = ext4_calloc(1, sizeof(struct ext4_buf));
if (!buf) {
ext4_free(data);
return nil;
}
buf->lba = lba;
buf->data = data;
buf->bc = bc;
return buf;
}
static void ext4_buf_free(struct ext4_buf *buf)
{
ext4_free(buf->data);
ext4_free(buf);
}
static struct ext4_buf *
ext4_buf_lookup(struct ext4_bcache *bc, u64int lba)
{
struct ext4_buf tmp = {
.lba = lba
};
return RB_FIND(ext4_buf_lba, &bc->lba_root, &tmp);
}
struct ext4_buf *ext4_buf_lowest_lru(struct ext4_bcache *bc)
{
return RB_MIN(ext4_buf_lru, &bc->lru_root);
}
void ext4_bcache_drop_buf(struct ext4_bcache *bc, struct ext4_buf *buf)
{
/* Warn on dropping any referenced buffers.*/
if (buf->refctr) {
ext4_dbg(DEBUG_BCACHE, DBG_WARN "Buffer is still referenced. "
"lba: %llud, refctr: %ud\n",
buf->lba, buf->refctr);
} else
RB_REMOVE(ext4_buf_lru, &bc->lru_root, buf);
RB_REMOVE(ext4_buf_lba, &bc->lba_root, buf);
/*Forcibly drop dirty buffer.*/
if (ext4_bcache_test_flag(buf, BC_DIRTY))
ext4_bcache_remove_dirty_node(bc, buf);
ext4_buf_free(buf);
bc->ref_blocks--;
}
void ext4_bcache_invalidate_buf(struct ext4_bcache *bc,
struct ext4_buf *buf)
{
buf->end_write = nil;
buf->end_write_arg = nil;
/* Clear both dirty and up-to-date flags. */
if (ext4_bcache_test_flag(buf, BC_DIRTY))
ext4_bcache_remove_dirty_node(bc, buf);
ext4_bcache_clear_dirty(buf);
}
void ext4_bcache_invalidate_lba(struct ext4_bcache *bc,
u64int from,
u32int cnt)
{
u64int end = from + cnt - 1;
struct ext4_buf *tmp = ext4_buf_lookup(bc, from), *buf;
RB_FOREACH_FROM(buf, ext4_buf_lba, tmp) {
if (buf->lba > end)
break;
ext4_bcache_invalidate_buf(bc, buf);
}
}
struct ext4_buf *
ext4_bcache_find_get(struct ext4_bcache *bc, struct ext4_block *b,
u64int lba)
{
struct ext4_buf *buf = ext4_buf_lookup(bc, lba);
if (buf) {
/* If buffer is not referenced. */
if (!buf->refctr) {
/* Assign new value to LRU id and increment LRU counter
* by 1*/
buf->lru_id = ++bc->lru_ctr;
RB_REMOVE(ext4_buf_lru, &bc->lru_root, buf);
if (ext4_bcache_test_flag(buf, BC_DIRTY))
ext4_bcache_remove_dirty_node(bc, buf);
}
ext4_bcache_inc_ref(buf);
b->lb_id = lba;
b->buf = buf;
b->data = buf->data;
}
return buf;
}
int ext4_bcache_alloc(struct ext4_bcache *bc, struct ext4_block *b,
bool *is_new)
{
/* Try to search the buffer with exaxt LBA. */
struct ext4_buf *buf = ext4_bcache_find_get(bc, b, b->lb_id);
if (buf) {
*is_new = false;
return 0;
}
/* We need to allocate one buffer.*/
buf = ext4_buf_alloc(bc, b->lb_id);
if (!buf) {
werrstr("memory");
return -1;
}
RB_INSERT(ext4_buf_lba, &bc->lba_root, buf);
/* One more buffer in bcache now. :-) */
bc->ref_blocks++;
/*Calc ref blocks max depth*/
if (bc->max_ref_blocks < bc->ref_blocks)
bc->max_ref_blocks = bc->ref_blocks;
ext4_bcache_inc_ref(buf);
/* Assign new value to LRU id and increment LRU counter
* by 1*/
buf->lru_id = ++bc->lru_ctr;
b->buf = buf;
b->data = buf->data;
*is_new = true;
return 0;
}
int ext4_bcache_free(struct ext4_bcache *bc, struct ext4_block *b)
{
struct ext4_buf *buf = b->buf;
assert(bc && b);
/*Check if valid.*/
if (!b->lb_id) {
werrstr("invalid block id");
return -1;
}
/*Block should have a valid pointer to ext4_buf.*/
assert(buf);
/*Check if someone don't try free unreferenced block cache.*/
assert(buf->refctr);
/*Just decrease reference counter*/
ext4_bcache_dec_ref(buf);
/* We are the last one touching this buffer, do the cleanups. */
if (!buf->refctr) {
RB_INSERT(ext4_buf_lru, &bc->lru_root, buf);
/* This buffer is ready to be flushed. */
if (ext4_bcache_test_flag(buf, BC_DIRTY) &&
ext4_bcache_test_flag(buf, BC_UPTODATE)) {
if (bc->bdev->cache_write_back &&
!ext4_bcache_test_flag(buf, BC_FLUSH) &&
!ext4_bcache_test_flag(buf, BC_TMP))
ext4_bcache_insert_dirty_node(bc, buf);
else {
ext4_block_flush_buf(bc->bdev, buf);
ext4_bcache_clear_flag(buf, BC_FLUSH);
}
}
/* The buffer is invalidated...drop it. */
if (!ext4_bcache_test_flag(buf, BC_UPTODATE) ||
ext4_bcache_test_flag(buf, BC_TMP))
ext4_bcache_drop_buf(bc, buf);
}
b->lb_id = 0;
b->data = 0;
return 0;
}
bool ext4_bcache_is_full(struct ext4_bcache *bc)
{
return (bc->cnt <= bc->ref_blocks);
}