mars/kernel/lib_mapfree.c

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2014-11-21 10:51:34 +00:00
/*
* MARS Long Distance Replication Software
*
* This file is part of MARS project: http://schoebel.github.io/mars/
*
* Copyright (C) 2010-2014 Thomas Schoebel-Theuer
* Copyright (C) 2011-2014 1&1 Internet AG
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "lib_mapfree.h"
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/file.h>
/* needed for symlink checking */
#include "sy_old/strategy.h"
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// time to wait between background mapfree operations
int mapfree_period_sec = 10;
EXPORT_SYMBOL_GPL(mapfree_period_sec);
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// some grace space where no regular cleanup should occur
int mapfree_grace_keep_mb = 16;
EXPORT_SYMBOL_GPL(mapfree_grace_keep_mb);
struct mf_hash_anchor {
struct rw_semaphore hash_mutex;
struct list_head hash_anchor;
struct task_struct *hash_thread;
};
#define MAPFREE_HASH 16
static inline
unsigned int mf_hash(const char *name)
{
unsigned char digest[MARS_DIGEST_SIZE] = {};
unsigned int res = 0;
mars_digest(MREF_CHKSUM_CRC32C | MREF_CHKSUM_MD5_OLD,
NULL,
digest,
name, strlen(name));
res = *(unsigned int *)&digest % MAPFREE_HASH;
return res;
}
static
struct mf_hash_anchor mf_table[MAPFREE_HASH];
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void mapfree_pages(struct mapfree_info *mf, int grace_keep)
{
struct address_space *mapping;
pgoff_t start;
pgoff_t end;
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if (unlikely(!mf))
goto done;
if (unlikely(!mf->mf_filp || !(mapping = mf->mf_filp->f_mapping)))
goto done;
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if (grace_keep < 0) { // force full flush
start = 0;
end = -1;
} else {
loff_t tmp;
loff_t min;
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down_write(&mf->mf_mutex);
min = tmp = mf->mf_min[0];
if (likely(mf->mf_min[1] < min))
min = mf->mf_min[1];
if (tmp) {
mf->mf_min[1] = tmp;
mf->mf_min[0] = 0;
}
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up_write(&mf->mf_mutex);
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min -= (loff_t)grace_keep * (1024 * 1024); // megabytes
end = 0;
if (min > 0 || mf->mf_last) {
start = mf->mf_last / PAGE_SIZE;
// add some grace overlapping
if (likely(start > 0))
start--;
mf->mf_last = min;
end = min / PAGE_SIZE;
} else { // there was no progress for at least 2 rounds
start = 0;
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if (!grace_keep) // also flush thoroughly
end = -1;
}
MARS_DBG("file = '%s' start = %lu end = %lu\n", SAFE_STR(mf->mf_name), start, end);
}
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if (end > start || end == -1) {
invalidate_mapping_pages(mapping, start, end);
}
done:;
}
static
void _mapfree_put(struct mapfree_info *mf)
{
if (atomic_dec_and_test(&mf->mf_count)) {
MARS_DBG("closing file '%s' filp = %p\n", mf->mf_name, mf->mf_filp);
list_del_init(&mf->mf_head);
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CHECK_HEAD_EMPTY(&mf->mf_dirty_anchor);
if (likely(mf->mf_filp)) {
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mapfree_pages(mf, -1);
filp_close(mf->mf_filp, NULL);
}
brick_string_free(mf->mf_name);
brick_mem_free(mf);
}
}
void mapfree_put(struct mapfree_info *mf)
{
if (likely(mf && mf->mf_hash < MAPFREE_HASH)) {
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unsigned int hash = mf->mf_hash;
down_write(&mf_table[hash].hash_mutex);
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_mapfree_put(mf);
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up_write(&mf_table[hash].hash_mutex);
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}
}
EXPORT_SYMBOL_GPL(mapfree_put);
struct mapfree_info *mapfree_get(const char *name, int flags)
{
struct mapfree_info *mf = NULL;
struct list_head *tmp;
unsigned int hash = mf_hash(name);
if (!(flags & O_DIRECT)) {
down_read(&mf_table[hash].hash_mutex);
for (tmp = mf_table[hash].hash_anchor.next;
tmp != &mf_table[hash].hash_anchor;
tmp = tmp->next) {
struct mapfree_info *_mf = container_of(tmp, struct mapfree_info, mf_head);
if (_mf->mf_flags == flags && !strcmp(_mf->mf_name, name)) {
mf = _mf;
atomic_inc(&mf->mf_count);
break;
}
}
up_read(&mf_table[hash].hash_mutex);
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if (mf) {
struct inode *inode = mf->mf_filp->f_mapping->host;
loff_t length;
int i;
/* In some cases like truncated logfiles,
* account for any shortenings.
*/
length = i_size_read(inode);
mf->mf_max = length;
for (i = 0; i < DIRTY_MAX; i++)
mf_dirty_reduce(mf, i, length);
goto done;
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}
}
for (;;) {
struct address_space *mapping;
struct inode *inode;
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loff_t length;
int i;
int ra = 1;
int prot = 0600;
mm_segment_t oldfs;
mf = brick_zmem_alloc(sizeof(struct mapfree_info));
if (unlikely(!mf)) {
MARS_ERR("no mem, name = '%s'\n", name);
continue;
}
mf->mf_hash = hash;
mf->mf_name = brick_strdup(name);
if (unlikely(!mf->mf_name)) {
MARS_ERR("no mem, name = '%s'\n", name);
brick_mem_free(mf);
continue;
}
/* allow replacement of a .deleted symlink */
if (flags & O_CREAT) {
const char *check = ordered_readlink(name, NULL);
if (check && !*check)
mars_unlink(name);
brick_string_free(check);
}
mf->mf_flags = flags;
INIT_LIST_HEAD(&mf->mf_head);
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INIT_LIST_HEAD(&mf->mf_dirty_anchor);
atomic_set(&mf->mf_count, 1);
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init_rwsem(&mf->mf_mutex);
mf->mf_max = -1;
oldfs = get_fs();
set_fs(get_ds());
mf->mf_filp = filp_open(name, flags, prot);
set_fs(oldfs);
MARS_DBG("file '%s' flags = %d prot = %d filp = %p\n", name, flags, prot, mf->mf_filp);
if (unlikely(!mf->mf_filp || IS_ERR(mf->mf_filp))) {
int err = PTR_ERR(mf->mf_filp);
MARS_ERR("can't open file '%s' status=%d\n", name, err);
mf->mf_filp = NULL;
_mapfree_put(mf);
mf = NULL;
break;
}
if (unlikely(!(mapping = mf->mf_filp->f_mapping) ||
!(inode = mapping->host))) {
MARS_ERR("file '%s' has no mapping\n", name);
mf->mf_filp = NULL;
_mapfree_put(mf);
mf = NULL;
break;
}
mapping_set_gfp_mask(mapping, mapping_gfp_mask(mapping) & ~(__GFP_IO | __GFP_FS));
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length = i_size_read(inode);
mf->mf_max = length;
for (i = 0; i < DIRTY_MAX; i++) {
rwlock_init(&mf->mf_length[i].dl_lock);
mf->mf_length[i].dl_length = length;
}
if (S_ISBLK(inode->i_mode)) {
#ifdef MARS_HAS_BDI_GET
struct backing_dev_info *bdi =
I_BDEV(inode)->bd_bdi;
MARS_INF("changing blkdev readahead from %lu to %d\n",
bdi->ra_pages, ra);
bdi->ra_pages = ra;
#else /* deprecated old code */
MARS_INF("changing blkdev readahead from %lu to %d\n", inode->i_bdev->bd_disk->queue->backing_dev_info.ra_pages, ra);
inode->i_bdev->bd_disk->queue->backing_dev_info.ra_pages = ra;
#endif
}
if (flags & O_DIRECT) { // never share them
break;
}
// maintain global list of all open files
down_write(&mf_table[hash].hash_mutex);
for (tmp = mf_table[hash].hash_anchor.next;
tmp != &mf_table[hash].hash_anchor;
tmp = tmp->next) {
struct mapfree_info *_mf = container_of(tmp, struct mapfree_info, mf_head);
if (unlikely(_mf->mf_flags == flags && !strcmp(_mf->mf_name, name))) {
MARS_WRN("race on creation of '%s' detected\n", name);
_mapfree_put(mf);
mf = _mf;
atomic_inc(&mf->mf_count);
goto leave;
}
}
list_add_tail(&mf->mf_head, &mf_table[hash].hash_anchor);
leave:
up_write(&mf_table[hash].hash_mutex);
break;
}
done:
return mf;
}
EXPORT_SYMBOL_GPL(mapfree_get);
void mapfree_set(struct mapfree_info *mf, loff_t min, loff_t max)
{
if (likely(mf && mf->mf_hash < MAPFREE_HASH)) {
struct mf_hash_anchor *mha = &mf_table[mf->mf_hash];
down_write(&mha->hash_mutex);
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if (!mf->mf_min[0] || mf->mf_min[0] > min)
mf->mf_min[0] = min;
if (max >= 0 && mf->mf_max < max)
mf->mf_max = max;
up_write(&mha->hash_mutex);
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}
}
EXPORT_SYMBOL_GPL(mapfree_set);
static
int mapfree_thread(void *data)
{
struct mf_hash_anchor *mha = data;
while (!brick_thread_should_stop()) {
struct mapfree_info *mf = NULL;
struct list_head *tmp;
long long eldest = 0;
brick_msleep(500);
if (mapfree_period_sec <= 0)
continue;
down_read(&mha->hash_mutex);
for (tmp = mha->hash_anchor.next;
tmp != &mha->hash_anchor;
tmp = tmp->next) {
struct mapfree_info *_mf = container_of(tmp, struct mapfree_info, mf_head);
if (unlikely(!_mf->mf_jiffies)) {
_mf->mf_jiffies = jiffies;
continue;
}
if ((long long)jiffies - _mf->mf_jiffies > mapfree_period_sec * HZ &&
(!mf || _mf->mf_jiffies < eldest)) {
mf = _mf;
eldest = _mf->mf_jiffies;
}
}
if (mf)
atomic_inc(&mf->mf_count);
up_read(&mha->hash_mutex);
if (!mf) {
continue;
}
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mapfree_pages(mf, mapfree_grace_keep_mb);
mf->mf_jiffies = jiffies;
mapfree_put(mf);
}
return 0;
}
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////////////////// dirty IOs in append mode //////////////////
static
struct dirty_length *_get_dl(struct mapfree_info *mf, enum dirty_stage stage)
{
#ifdef MARS_DEBUGGING
if (unlikely(stage < 0)) {
MARS_ERR("bad stage=%d\n", stage);
stage = 0;
}
if (unlikely(stage >= DIRTY_MAX)) {
MARS_ERR("bad stage=%d\n", stage);
stage = DIRTY_MAX - 1;
}
#endif
return &mf->mf_length[stage];
}
void mf_dirty_append(struct mapfree_info *mf, enum dirty_stage stage, loff_t newlen)
{
struct dirty_length *dl = _get_dl(mf, stage);
unsigned long flags;
traced_writelock(&dl->dl_lock, flags);
if (dl->dl_length < newlen)
dl->dl_length = newlen;
traced_writeunlock(&dl->dl_lock, flags);
}
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void mf_dirty_reduce(struct mapfree_info *mf, enum dirty_stage stage, loff_t newlen)
{
struct dirty_length *dl = _get_dl(mf, stage);
unsigned long flags;
traced_writelock(&dl->dl_lock, flags);
if (dl->dl_length > newlen)
dl->dl_length = newlen;
traced_writeunlock(&dl->dl_lock, flags);
}
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loff_t mf_dirty_length(struct mapfree_info *mf, enum dirty_stage stage)
{
struct dirty_length *dl = _get_dl(mf, stage);
#ifdef CONFIG_64BIT
/* Avoid locking by assuming that 64bit reads are atomic in itself */
smp_read_barrier_depends();
return ACCESS_ONCE(dl->dl_length);
#else /* cannot rely on atomic read of two 32bit values */
loff_t res;
unsigned long flags;
traced_readlock(&dl->dl_lock, flags);
res = dl->dl_length;
traced_readunlock(&dl->dl_lock, flags);
return res;
#endif
}
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////////////////// dirty IOs on the fly //////////////////
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loff_t mf_get_any_dirty(const char *filename, int stage)
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{
unsigned int hash = mf_hash(filename);
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loff_t res = -1;
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struct list_head *tmp;
down_read(&mf_table[hash].hash_mutex);
for (tmp = mf_table[hash].hash_anchor.next;
tmp != &mf_table[hash].hash_anchor;
tmp = tmp->next) {
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struct mapfree_info *mf = container_of(tmp, struct mapfree_info, mf_head);
if (!strcmp(mf->mf_name, filename)) {
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res = mf_dirty_length(mf, stage);
break;
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}
}
up_read(&mf_table[hash].hash_mutex);
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return res;
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}
EXPORT_SYMBOL_GPL(mf_get_any_dirty);
////////////////// module init stuff /////////////////////////
int __init init_mars_mapfree(void)
{
int i;
MARS_DBG("init_mapfree()\n");
for (i = 0; i < MAPFREE_HASH; i++) {
struct task_struct *thread;
init_rwsem(&mf_table[i].hash_mutex);
INIT_LIST_HEAD(&mf_table[i].hash_anchor);
thread = brick_thread_create(mapfree_thread,
&mf_table[i],
"mars_mf%d", i);
if (unlikely(!thread)) {
MARS_ERR("could not create mapfree thread %d\n", i);
return -ENOMEM;
}
mf_table[i].hash_thread = thread;
}
return 0;
}
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void exit_mars_mapfree(void)
{
int i;
MARS_DBG("exit_mapfree()\n");
for (i = 0; i < MAPFREE_HASH; i++) {
if (likely(mf_table[i].hash_thread)) {
brick_thread_stop(mf_table[i].hash_thread);
mf_table[i].hash_thread = NULL;
}
CHECK_HEAD_EMPTY(&mf_table[i].hash_anchor);
}
}