308 lines
6.5 KiB
C
308 lines
6.5 KiB
C
/*
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* Copyright (c) 2019 Tom Marshall <tdm.code@gmail.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/bio.h>
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#include <linux/device-mapper.h>
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#include <linux/workqueue.h>
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#include <linux/mutex.h>
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#include <linux/lz4.h>
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#include <linux/dm-compress.h>
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struct lbatpage {
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u64 pblk;
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struct mutex reflock;
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unsigned int ref;
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struct mutex lock;
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struct cbd_params* params;
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struct page* page;
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u8* buf;
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bool dirty;
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};
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static bool
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lbatpage_ctr(struct lbatpage* lp, struct cbd_params* params)
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{
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lp->pblk = PBLK_NONE;
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mutex_init(&lp->reflock);
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lp->ref = 0;
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mutex_init(&lp->lock);
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lp->params = params;
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lp->page = cbd_alloc_page();
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if (!lp->page) {
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return false;
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}
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lp->buf = page_address(lp->page);
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lp->dirty = false;
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return true;
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}
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static void
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lbatpage_dtr(struct lbatpage* lp)
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{
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lp->buf = NULL;
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cbd_free_page(lp->page);
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lp->page = NULL;
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}
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static bool
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lbatpage_error(struct lbatpage* lp)
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{
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return PageError(lp->page);
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}
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static int
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lbatpage_flush(struct lbatpage* lp)
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{
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int ret = 0;
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struct page* iopagev[1];
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mutex_lock(&lp->lock);
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if (!PageDirty(lp->page)) {
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goto unlock;
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}
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if (lbatpage_error(lp)) {
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ret = -EIO;
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goto unlock;
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}
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iopagev[0] = lp->page;
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pblk_write(lp->params->priv, lp->pblk, 1, iopagev);
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mutex_unlock(&lp->lock);
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return ret;
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unlock:
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unlock_page(lp->page);
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mutex_unlock(&lp->lock);
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return ret;
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}
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static int
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lbatpage_read(struct lbatpage* lp)
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{
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int ret = 0;
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struct page* pagev[1];
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pagev[0] = lp->page;
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ret = pblk_read_wait(lp->params->priv, lp->pblk, 1, pagev);
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return ret;
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}
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static int
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lbatpage_reset(struct lbatpage* lp, u64 pblk)
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{
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int ret = 0;
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lock_page(lp->page);
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if (lp->pblk != pblk) {
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lp->pblk = pblk;
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ret = lbatpage_read(lp);
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}
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if (ret) {
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unlock_page(lp->page);
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lp->pblk = PBLK_NONE;
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}
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return ret;
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}
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u8*
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lbatpage_get_buf(struct lbatpage* lp, bool rw)
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{
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mutex_lock(&lp->lock);
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if (rw) {
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SetPageDirty(lp->page);
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}
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return lp->buf;
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}
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void
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lbatpage_put_buf(struct lbatpage* lp)
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{
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mutex_unlock(&lp->lock);
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}
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struct lbatpagecache {
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struct mutex lock;
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struct cbd_params* params;
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unsigned int len;
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struct lbatpage** cache;
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};
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size_t
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lbatpagecache_size(void)
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{
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return sizeof(struct lbatpagecache);
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}
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static bool
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lbatpagecache_realloc(struct lbatpagecache* lpc, unsigned int len)
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{
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struct lbatpage** cache;
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unsigned int n;
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struct lbatpage* lp;
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cache = kzalloc(len * sizeof(struct lbatpage*), GFP_KERNEL);
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if (!cache) {
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return false;
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}
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n = 0;
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if (lpc->len) {
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memcpy(cache, lpc->cache, lpc->len * sizeof(struct lbatpage*));
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n = lpc->len;
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kfree(lpc->cache);
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}
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lpc->len = len;
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lpc->cache = cache;
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while (n < len) {
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lp = kmalloc(sizeof(struct lbatpage), GFP_KERNEL);
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if (!lp) {
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return false;
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}
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cache[n++] = lp;
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if (!lbatpage_ctr(lp, lpc->params)) {
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return false;
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}
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}
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return true;
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}
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bool
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lbatpagecache_ctr(struct lbatpagecache* lpc,
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struct cbd_params* params)
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{
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memset(lpc, 0, sizeof(struct lbatpagecache));
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mutex_init(&lpc->lock);
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lpc->params = params;
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return lbatpagecache_realloc(lpc, 1);
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}
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void
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lbatpagecache_dtr(struct lbatpagecache* lpc)
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{
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unsigned int n;
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struct lbatpage* lp;
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for (n = 0; n < lpc->len; ++n) {
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lp = lpc->cache[n];
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if (!lp) {
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continue;
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}
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lbatpage_dtr(lp);
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if (lp->ref) {
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printk(KERN_ERR "%s: lbatpage ref leak: n=%u ref=%u\n", __func__, n, lp->ref);
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}
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kfree(lp);
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}
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kfree(lpc->cache);
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lpc->cache = NULL;
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lpc->len = 0;
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lpc->params = NULL;
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}
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struct lbatpage*
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lbatpagecache_get(struct lbatpagecache* lpc, u64 pblk)
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{
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unsigned int n;
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struct lbatpage* lp;
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mutex_lock(&lpc->lock);
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for (n = 0; n < lpc->len; ++n) {
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lp = lpc->cache[n];
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mutex_lock(&lp->reflock);
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if (lp->pblk == pblk) {
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if (lp->ref == 0) {
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goto found;
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}
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mutex_unlock(&lpc->lock);
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++lp->ref;
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mutex_unlock(&lp->reflock);
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return lp;
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}
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mutex_unlock(&lp->reflock);
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}
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for (n = 0; n < lpc->len; ++n) {
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lp = lpc->cache[n];
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mutex_lock(&lp->reflock);
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if (lp->pblk == PBLK_NONE) {
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goto found;
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}
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mutex_unlock(&lp->reflock);
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}
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for (n = 0; n < lpc->len; ++n) {
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lp = lpc->cache[n];
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mutex_lock(&lp->reflock);
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if (lp->ref == 0 && !lbatpage_error(lp)) {
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goto found;
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}
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mutex_unlock(&lp->reflock);
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}
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n = lpc->len;
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if (!lbatpagecache_realloc(lpc, lpc->len * 2)) {
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printk(KERN_ERR "%s: realloc failed\n", __func__);
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mutex_unlock(&lpc->lock);
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return NULL;
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}
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lp = lpc->cache[n];
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mutex_lock(&lp->reflock);
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found:
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mutex_unlock(&lpc->lock);
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if (lbatpage_reset(lp, pblk) != 0) {
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mutex_unlock(&lp->reflock);
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return NULL;
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}
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lp->ref = 1;
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mutex_unlock(&lp->reflock);
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return lp;
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}
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int
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lbatpagecache_put(struct lbatpagecache* lpc, struct lbatpage* lp)
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{
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int ret = 0;
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if (!lp) {
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return 0;
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}
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mutex_lock(&lp->reflock);
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if (--lp->ref == 0) {
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ret = lbatpage_flush(lp);
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if (ret) {
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printk(KERN_ERR "%s: lbatpage_flush failed\n", __func__);
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}
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}
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mutex_unlock(&lp->reflock);
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return ret;
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}
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