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mars/kernel/mars_aio.c
Thomas Schoebel-Theuer 8544ef4117 aio: safeguard potential race on fd_uninstall
2021-03-02 10:12:56 +01:00

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/*
* 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.
*/
//#define BRICK_DEBUGGING
#define MARS_DEBUGGING
//#define IO_DEBUGGING
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/version.h>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/types.h>
#include <linux/blkdev.h>
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/file.h>
#include "mars.h"
#include "lib_timing.h"
#include "lib_mapfree.h"
#include "mars_aio.h"
#if !defined(MARS_HAS_PREPATCH_V2) && !defined(MARS_HAS_PREPATCH)
#warning You are compiling without pre-patch, resulting in BAD IO PERFORMANCE
#endif
#define MARS_MAX_AIO 512
#define MARS_MAX_AIO_READ 32
/* Self-tune aio_max_nr when possible.
* This works only when the pre-patch has
* EXPORT_SYNBOL_GPL(aio_max_nr) and has
* defined HAS_AIO_MAX.
*/
#ifdef HAS_AIO_MAX
static DEFINE_MUTEX(aio_max_lock);
int aio_max_nr_current = 0;
int aio_max_nr_max = 0;
#endif
struct timing_stats timings[3] = {};
struct threshold aio_submit_threshold = {
.thr_ban = &mars_global_ban,
.thr_parent = &global_io_threshold,
.thr_limit = AIO_SUBMIT_MAX_LATENCY,
.thr_factor = 10,
.thr_plus = 10000,
};
EXPORT_SYMBOL_GPL(aio_submit_threshold);
struct threshold aio_io_threshold[2] = {
[0] = {
.thr_ban = &mars_global_ban,
.thr_parent = &global_io_threshold,
.thr_limit = AIO_IO_R_MAX_LATENCY,
.thr_factor = 100,
.thr_plus = 0,
},
[1] = {
.thr_ban = &mars_global_ban,
.thr_parent = &global_io_threshold,
.thr_limit = AIO_IO_W_MAX_LATENCY,
.thr_factor = 100,
.thr_plus = 0,
},
};
EXPORT_SYMBOL_GPL(aio_io_threshold);
struct threshold aio_sync_threshold = {
.thr_ban = &mars_global_ban,
.thr_limit = AIO_SYNC_MAX_LATENCY,
.thr_factor = 100,
.thr_plus = 0,
};
EXPORT_SYMBOL_GPL(aio_sync_threshold);
int aio_sync_mode = 2;
EXPORT_SYMBOL_GPL(aio_sync_mode);
///////////////////////// own type definitions ////////////////////////
////////////////// some helpers //////////////////
#ifdef ENABLE_MARS_AIO
static inline
void _enqueue(struct aio_threadinfo *tinfo, struct aio_mref_aspect *mref_a, int prio, bool at_end)
{
#if 1
prio++;
if (unlikely(prio < 0)) {
prio = 0;
} else if (unlikely(prio >= MARS_PRIO_NR)) {
prio = MARS_PRIO_NR - 1;
}
#else
prio = 0;
#endif
mref_a->enqueue_stamp = cpu_clock(raw_smp_processor_id());
mutex_lock(&tinfo->mutex);
if (at_end) {
list_add_tail(&mref_a->io_head, &tinfo->mref_list[prio]);
} else {
list_add(&mref_a->io_head, &tinfo->mref_list[prio]);
}
tinfo->queued[prio]++;
atomic_inc(&tinfo->queued_sum);
mutex_unlock(&tinfo->mutex);
#ifdef MARS_AIO_DEBUG
atomic_inc(&tinfo->total_enqueue_count);
#endif
wake_up_interruptible_all(&tinfo->event);
}
static inline
struct aio_mref_aspect *_dequeue(struct aio_threadinfo *tinfo)
{
struct aio_mref_aspect *mref_a = NULL;
int prio;
mutex_lock(&tinfo->mutex);
for (prio = 0; prio < MARS_PRIO_NR; prio++) {
struct list_head *start = &tinfo->mref_list[prio];
struct list_head *tmp = start->next;
if (tmp != start) {
list_del_init(tmp);
tinfo->queued[prio]--;
atomic_dec(&tinfo->queued_sum);
mref_a = container_of(tmp, struct aio_mref_aspect, io_head);
goto done;
}
}
done:
mutex_unlock(&tinfo->mutex);
if (likely(mref_a && mref_a->object)) {
unsigned long long latency;
int rw = mref_a->object->ref_flags & MREF_WRITE ? 1 : 0;
latency = cpu_clock(raw_smp_processor_id()) - mref_a->enqueue_stamp;
threshold_check(&aio_io_threshold[rw], latency);
}
return mref_a;
}
////////////////// own brick / input / output operations //////////////////
static
loff_t get_total_size(struct aio_output *output)
{
/* Workaround for races in the page cache.
* It appears that concurrent reads and writes seem to
* result in inconsistent reads in some very rare cases, due to
* races. Sometimes, the inode claims that the file has been already
* appended by a write operation, but the data has not actually hit
* the page cache, such that a concurrent read gets NULL blocks.
*/
return mf_dirty_length(output->mf, DIRTY_COMPLETED);
}
static int aio_ref_get(struct aio_output *output, struct mref_object *mref)
{
loff_t total_size;
if (unlikely(!output->brick->power.led_on))
return -EBADFD;
if (unlikely(!output->mf)) {
MARS_ERR("brick is not switched on\n");
return -EILSEQ;
}
if (unlikely(mref->ref_len <= 0)) {
MARS_ERR("bad ref_len=%d\n", mref->ref_len);
return -EILSEQ;
}
total_size = get_total_size(output);
if (unlikely(total_size < 0)) {
return total_size;
}
mref->ref_total_size = total_size;
if (mref->ref_initialized) {
_mref_get(mref);
return mref->ref_len;
}
/* Buffered IO.
*/
if (!mref->ref_data) {
struct aio_mref_aspect *mref_a = aio_mref_get_aspect(output->brick, mref);
if (unlikely(!mref_a)) {
MARS_ERR("bad mref_a\n");
return -EILSEQ;
}
if (unlikely(mref->ref_len <= 0)) {
MARS_ERR("bad ref_len = %d\n", mref->ref_len);
return -ENOMEM;
}
mref->ref_data = brick_block_alloc(mref->ref_pos, (mref_a->alloc_len = mref->ref_len));
if (unlikely(!mref->ref_data)) {
MARS_ERR("ENOMEM %d bytes\n", mref->ref_len);
return -ENOMEM;
}
mref_a->do_dealloc = true;
#ifdef MARS_AIO_DEBUG
atomic_inc(&output->total_alloc_count);
atomic_inc(&output->alloc_count);
#endif
}
_mref_get_first(mref);
return mref->ref_len;
}
static void aio_ref_put(struct aio_output *output, struct mref_object *mref)
{
struct file *file;
struct aio_mref_aspect *mref_a;
if (!_mref_put(mref)) {
goto done;
}
if (output->mf && (file = output->mf->mf_filp) && file->f_mapping && file->f_mapping->host) {
mref->ref_total_size = get_total_size(output);
}
mref_a = aio_mref_get_aspect(output->brick, mref);
if (mref_a && mref_a->do_dealloc) {
brick_block_free(mref->ref_data, mref_a->alloc_len);
#ifdef MARS_AIO_DEBUG
atomic_dec(&output->alloc_count);
#endif
}
aio_free_mref(mref);
done:;
}
static
void _complete(struct aio_output *output, struct aio_mref_aspect *mref_a, int err)
{
struct mref_object *mref;
bool was_write;
CHECK_PTR(mref_a, fatal);
mref = mref_a->object;
CHECK_PTR(mref, fatal);
mars_trace(mref, "aio_endio");
if (err < 0) {
MARS_ERR("IO error %d at pos=%lld len=%d (mref=%p ref_data=%p)\n", err, mref->ref_pos, mref->ref_len, mref, mref->ref_data);
} else {
mref_checksum(mref);
mref->ref_flags |= MREF_UPTODATE;
}
was_write = (mref->ref_flags & MREF_WRITE);
if (was_write) {
/* Needs to be done before callback, which might modify
* mref->.+
*/
mf_dirty_append(output->mf, DIRTY_FINISHED, mref->ref_pos + mref->ref_len);
}
CHECKED_CALLBACK(mref, err, err_found);
done:
if (was_write) {
atomic_dec(&output->write_count);
} else {
atomic_dec(&output->read_count);
}
aio_ref_put(output, mref);
atomic_dec(&output->work_count);
atomic_dec(&mars_global_io_flying);
return;
err_found:
MARS_FAT("giving up...\n");
goto done;
fatal:
MARS_FAT("bad pointer, giving up...\n");
}
static
void _complete_mref(struct aio_output *output, struct mref_object *mref, int err)
{
struct aio_mref_aspect *mref_a;
_mref_check(mref);
mref_a = aio_mref_get_aspect(output->brick, mref);
CHECK_PTR(mref_a, fatal);
_complete(output, mref_a, err);
return;
fatal:
MARS_FAT("bad pointer, giving up...\n");
}
static
void _complete_all(struct list_head *tmp_list, struct aio_output *output, int err)
{
while (!list_empty(tmp_list)) {
struct list_head *tmp = tmp_list->next;
struct aio_mref_aspect *mref_a = container_of(tmp, struct aio_mref_aspect, io_head);
list_del_init(tmp);
_complete(output, mref_a, err);
}
}
static void aio_ref_io(struct aio_output *output, struct mref_object *mref)
{
struct aio_threadinfo *tinfo = &output->tinfo[0];
struct aio_mref_aspect *mref_a;
int err = -EINVAL;
_mref_check(mref);
if (unlikely(!output->brick->power.led_on)) {
SIMPLE_CALLBACK(mref, -EBADFD);
return;
}
_mref_get(mref);
atomic_inc(&mars_global_io_flying);
atomic_inc(&output->work_count);
// statistics
if (mref->ref_flags & MREF_WRITE) {
#ifdef MARS_AIO_DEBUG
atomic_inc(&output->total_write_count);
#endif
atomic_inc(&output->write_count);
} else {
#ifdef MARS_AIO_DEBUG
atomic_inc(&output->total_read_count);
#endif
atomic_inc(&output->read_count);
}
if (unlikely(!output->mf || !output->mf->mf_filp)) {
goto done;
}
mapfree_set(output->mf, mref->ref_pos, -1);
MARS_IO("AIO flags=%ux pos=%lld len=%d data=%p\n",
mref->ref_flags, mref->ref_pos, mref->ref_len, mref->ref_data);
mref_a = aio_mref_get_aspect(output->brick, mref);
if (unlikely(!mref_a)) {
goto done;
}
_enqueue(tinfo, mref_a, mref->ref_prio, true);
return;
done:
_complete_mref(output, mref, err);
}
static int aio_submit(struct aio_output *output, struct aio_mref_aspect *mref_a, bool use_fdsync)
{
struct mref_object *mref = mref_a->object;
mm_segment_t oldfs;
int res;
__u32 rw = mref->ref_flags & MREF_WRITE ? 1 : 0;
struct iocb iocb = {
.aio_data = (__u64)mref_a,
.aio_lio_opcode = use_fdsync ? IOCB_CMD_FDSYNC : (rw ? IOCB_CMD_PWRITE : IOCB_CMD_PREAD),
.aio_fildes = output->fd,
.aio_buf = (unsigned long)mref->ref_data,
.aio_nbytes = mref->ref_len,
.aio_offset = mref->ref_pos,
// .aio_reqprio = something(mref->ref_prio) field exists, but not yet implemented in kernelspace :(
};
struct iocb *iocbp = &iocb;
struct timing_stats *this_timing = &timings[rw];
unsigned long long latency;
mars_trace(mref, "aio_submit");
if (unlikely(output->fd < 0)) {
MARS_ERR("bad fd = %d\n", output->fd);
res = -EBADF;
goto done;
}
oldfs = get_fs();
set_fs(KERNEL_DS);
latency = TIME_STATS(
this_timing,
#ifdef MARS_HAS_PREPATCH_V2
res = ksys_io_submit(output->ctxp, 1, &iocbp)
#else
res = sys_io_submit(output->ctxp, 1, &iocbp)
#endif
);
set_fs(oldfs);
threshold_check(&aio_submit_threshold, latency);
#ifdef MARS_AIO_DEBUG
atomic_inc(&output->total_submit_count);
#endif
if (likely(res >= 0)) {
atomic_inc(&output->submit_count);
} else if (likely(res == -EAGAIN)) {
#ifdef MARS_AIO_DEBUG
atomic_inc(&output->total_again_count);
#endif
} else {
MARS_ERR("error = %d\n", res);
}
wake_up_interruptible_all(&output->tinfo[1].event);
done:
return res;
}
static int aio_submit_dummy(struct aio_output *output)
{
mm_segment_t oldfs;
int res;
int dummy;
struct iocb iocb = {
.aio_buf = (__u64)&dummy,
};
struct iocb *iocbp = &iocb;
oldfs = get_fs();
set_fs(KERNEL_DS);
#ifdef MARS_HAS_PREPATCH_V2
res = ksys_io_submit(output->ctxp, 1, &iocbp);
#else
res = sys_io_submit(output->ctxp, 1, &iocbp);
#endif
set_fs(oldfs);
if (likely(res >= 0)) {
atomic_inc(&output->submit_count);
}
return res;
}
static
int aio_start_thread(
struct aio_output *output,
struct aio_threadinfo *tinfo,
int(*fn)(void*),
char class)
{
int j;
for (j = 0; j < MARS_PRIO_NR; j++) {
INIT_LIST_HEAD(&tinfo->mref_list[j]);
}
tinfo->output = output;
mutex_init(&tinfo->mutex);
init_waitqueue_head(&tinfo->event);
init_waitqueue_head(&tinfo->terminate_event);
tinfo->should_terminate = false;
tinfo->terminated = false;
tinfo->thread = brick_thread_create(fn, tinfo, "mars_aio_%c%d", class, output->index);
if (unlikely(!tinfo->thread)) {
MARS_ERR("cannot create thread\n");
return -ENOENT;
}
return 0;
}
static
void aio_stop_thread(struct aio_output *output, int i, bool do_submit_dummy)
{
struct aio_threadinfo *tinfo = &output->tinfo[i];
struct task_struct *thread = tinfo->thread;
if (thread) {
MARS_DBG("stopping thread %d ...\n", i);
tinfo->should_terminate = true;
// workaround for waking up the receiver thread. TODO: check whether signal handlong could do better.
if (do_submit_dummy) {
MARS_DBG("submitting dummy for wakeup %d...\n", i);
use_fake_mm();
aio_submit_dummy(output);
if (likely(current->mm)) {
unuse_fake_mm();
}
}
wake_up_interruptible_all(&tinfo->event);
// wait for termination
MARS_DBG("waiting for thread %d ...\n", i);
wait_event_interruptible_timeout(
tinfo->terminate_event,
tinfo->terminated,
(60 - i * 2) * HZ);
if (likely(tinfo->terminated)) {
brick_thread_stop(tinfo->thread);
} else {
MARS_ERR("thread %d did not terminate - leaving a zombie\n", i);
}
}
}
static
int aio_sync(struct file *file)
{
int err;
switch (aio_sync_mode) {
case 1:
#if defined(S_BIAS) || (defined(RHEL_MAJOR) && (RHEL_MAJOR < 7))
err = vfs_fsync_range(file, file->f_path.dentry, 0, LLONG_MAX, 1);
#else
err = vfs_fsync_range(file, 0, LLONG_MAX, 1);
#endif
break;
case 2:
#if defined(S_BIAS) || (defined(RHEL_MAJOR) && (RHEL_MAJOR < 7))
err = vfs_fsync_range(file, file->f_path.dentry, 0, LLONG_MAX, 0);
#else
err = vfs_fsync_range(file, 0, LLONG_MAX, 0);
#endif
break;
default:
err = filemap_write_and_wait_range(file->f_mapping, 0, LLONG_MAX);
}
return err;
}
static
void aio_sync_all(struct aio_output *output, struct list_head *tmp_list)
{
unsigned long long latency;
int err;
output->fdsync_active = true;
#ifdef MARS_AIO_DEBUG
atomic_inc(&output->total_fdsync_count);
#endif
latency = TIME_STATS(
&timings[2],
err = aio_sync(output->mf->mf_filp)
);
threshold_check(&aio_sync_threshold, latency);
output->fdsync_active = false;
wake_up_interruptible_all(&output->fdsync_event);
if (err < 0) {
MARS_ERR("FDSYNC error %d\n", err);
}
/* Signal completion for the whole list.
* No locking needed, it's on the stack.
*/
_complete_all(tmp_list, output, err);
}
/* Workaround for non-implemented aio_fsync()
*/
static
int aio_sync_thread(void *data)
{
struct aio_threadinfo *tinfo = data;
struct aio_output *output = tinfo->output;
MARS_DBG("sync thread has started on '%s'.\n", output->brick->brick_path);
//set_user_nice(current, -20);
while (!tinfo->should_terminate || atomic_read(&tinfo->queued_sum) > 0) {
LIST_HEAD(tmp_list);
int i;
output->fdsync_active = false;
wake_up_interruptible_all(&output->fdsync_event);
wait_event_interruptible_timeout(
tinfo->event,
atomic_read(&tinfo->queued_sum) > 0 ||
tinfo->should_terminate,
HZ / 4);
mutex_lock(&tinfo->mutex);
for (i = 0; i < MARS_PRIO_NR; i++) {
struct list_head *start = &tinfo->mref_list[i];
if (!list_empty(start)) {
// move over the whole list
list_replace_init(start, &tmp_list);
atomic_sub(tinfo->queued[i], &tinfo->queued_sum);
tinfo->queued[i] = 0;
break;
}
}
mutex_unlock(&tinfo->mutex);
if (!list_empty(&tmp_list)) {
aio_sync_all(output, &tmp_list);
}
}
MARS_DBG("sync thread has stopped.\n");
tinfo->terminated = true;
wake_up_interruptible_all(&tinfo->terminate_event);
return 0;
}
static int aio_event_thread(void *data)
{
struct aio_threadinfo *tinfo = data;
struct aio_output *output = tinfo->output;
struct aio_brick *brick = output->brick;
struct aio_threadinfo *other = &output->tinfo[2];
struct io_event *events;
int err = -ENOMEM;
events = brick_mem_alloc(sizeof(struct io_event) * MARS_MAX_AIO_READ);
MARS_DBG("event thread has started.\n");
//set_user_nice(current, -20);
use_fake_mm();
if (!current->mm)
goto err;
err = aio_start_thread(output, &output->tinfo[2], aio_sync_thread, 'y');
if (unlikely(err < 0))
goto err;
while (!tinfo->should_terminate || atomic_read(&tinfo->queued_sum) > 0) {
mm_segment_t oldfs;
int count;
int i;
#ifdef MARS_HAS_SO_SNDTIMEO_NEW
struct __kernel_timespec timeout = {
.tv_nsec =
tinfo->should_terminate ||
!brick->power.button ? 0 : 100000,
};
#else
struct timespec timeout = {
.tv_nsec =
tinfo->should_terminate ||
!brick->power.button ? 0 : 100000,
};
#endif
if (unlikely(!(void*)output->ctxp)) {
MARS_ERR("Oops, context vanished. queued_sum = %d\n", atomic_read(&tinfo->queued_sum));
break;
}
#ifdef CONFIG_MARS_DEBUG
if (mars_hang_mode & 1) {
brick_msleep(100);
continue;
}
#endif
oldfs = get_fs();
set_fs(KERNEL_DS);
/* TODO: don't timeout upon termination.
* Probably we should submit a dummy request.
*/
#ifdef MARS_HAS_PREPATCH_V2
count = ksys_io_getevents(output->ctxp, 1, MARS_MAX_AIO_READ, events, &timeout);
#else
count = sys_io_getevents(output->ctxp, 1, MARS_MAX_AIO_READ, events, &timeout);
#endif
set_fs(oldfs);
if (count > 0) {
atomic_sub(count, &output->submit_count);
} else if (!count) {
wait_event_interruptible_timeout(
tinfo->event,
atomic_read(&output->submit_count) > 0 ||
tinfo->should_terminate,
HZ / 4);
continue;
}
for (i = 0; i < count; i++) {
struct aio_mref_aspect *mref_a = (void*)events[i].data;
struct mref_object *mref;
int err = events[i].res;
if (!mref_a) {
continue; // this was a dummy request
}
mref = mref_a->object;
MARS_IO("AIO done %p pos = %lld len = %d flags = %ux\n",
mref, mref->ref_pos, mref->ref_len,
mref->ref_flags);
mapfree_set(output->mf, mref->ref_pos, mref->ref_pos + mref->ref_len);
if (mref->ref_flags & MREF_WRITE)
mf_dirty_append(output->mf, DIRTY_COMPLETED, mref->ref_pos + mref->ref_len);
/* Workaround for never implemented aio_fsync operation,
* see also upstream commit 723c038475b78edc9327eb952f95f9881cc9d7.
* FIXME: don't use aio anymore at all in the long-term future.
*/
if (output->brick->o_fdsync &&
err >= 0 &&
(mref->ref_flags & MREF_WRITE) &&
!(mref->ref_flags & MREF_SKIP_SYNC) &&
!mref_a->resubmit++) {
mars_trace(mref, "aio_fsync");
_enqueue(other, mref_a, mref->ref_prio, true);
continue;
}
_complete(output, mref_a, err);
}
}
err = 0;
err:
MARS_DBG("event thread has stopped, err = %d\n", err);
aio_stop_thread(output, 2, false);
unuse_fake_mm();
tinfo->terminated = true;
wake_up_interruptible_all(&tinfo->terminate_event);
brick_mem_free(events);
return err;
}
#if 1
/* This should go to fs/open.c (as long as vfs_submit() is not implemented)
*/
#include <linux/fdtable.h>
void fd_uninstall(unsigned int fd)
{
struct files_struct *files = current->files;
struct fdtable *fdt;
unsigned long flags;
MARS_DBG("fd = %d\n", fd);
if (unlikely(fd < 0)) {
MARS_ERR("bad fd = %d\n", fd);
return;
}
spin_lock_irqsave(&files->file_lock, flags);
fdt = files_fdtable(files);
rcu_assign_pointer(fdt->fd[fd], NULL);
spin_unlock_irqrestore(&files->file_lock, flags);
}
EXPORT_SYMBOL(fd_uninstall);
#endif
static
atomic_t ioctx_count = ATOMIC_INIT(0);
static DEFINE_MUTEX(_fd_lock);
static
void _destroy_ioctx(struct aio_output *output)
{
int fd;
if (unlikely(!output))
goto done;
aio_stop_thread(output, 1, true);
use_fake_mm();
if (likely(output->ctxp)) {
mm_segment_t oldfs;
int err;
MARS_DBG("ioctx count = %d destroying %p\n", atomic_read(&ioctx_count), (void*)output->ctxp);
oldfs = get_fs();
set_fs(KERNEL_DS);
#ifdef MARS_HAS_PREPATCH_V2
err = ksys_io_destroy(output->ctxp);
#else
err = sys_io_destroy(output->ctxp);
#endif
set_fs(oldfs);
atomic_dec(&ioctx_count);
MARS_DBG("ioctx count = %d status = %d\n", atomic_read(&ioctx_count), err);
output->ctxp = 0;
#ifdef HAS_AIO_MAX
mutex_lock(&aio_max_lock);
aio_max_nr_current -= MARS_MAX_AIO;
mutex_unlock(&aio_max_lock);
#endif
}
mutex_lock(&_fd_lock);
fd = output->fd;
if (likely(fd >= 0)) {
MARS_DBG("destroying fd %d\n", fd);
fd_uninstall(fd);
put_unused_fd(fd);
output->fd = -1;
}
mutex_unlock(&_fd_lock);
done:
if (likely(current->mm)) {
unuse_fake_mm();
}
}
/* TODO: this is provisionary. We only need it for sys_io_submit()
* which uses userspace concepts like file handles.
* This should be replaced by a future kernelsapce vfs_submit() or
* do_submit() which currently does not exist :(
* Or, the whole aio brick should be replaced by something else.
* A good candidate could be the new {read,write}_iter() infrastructure.
* But only present at newer kernels.
* Unfortunately I will have to support old kernels for a while :(
*/
static int _get_fd(void)
{
struct files_struct *files;
int err = -EINVAL;
int count = 0;
do {
mutex_lock(&_fd_lock);
files = current->files;
CHECK_PTR(files, done);
/* Workaround upstream bug:
* Commit 8a81252b774b53e628a8a0fe18e2b8fc236d92cc
* forgot to initialize the new field resize_wait in
* fs/file.c in the initializer of init_files.
* We detect whether this commit is present via neighbor
* commit a7928c1578c550bd6f4dec62d65132e6db226c57
* which removed the ancient define for blk_pm_request.
* Once the bug is fixed in all relevant upstream LTS kernels
* and in all relevant distro kernels, this hack should be
* removed again.
*/
#ifndef blk_pm_request
/* Upstream commit 2055da97389a605c8a00d163d40903afbe413921
* changed the field name.
* Detected via 8ada92799ec4de00f4bc0f10b1ededa256c1ab22
*/
#ifdef wait_event_killable_timeout
#define XXX_NAME head
#else
#define XXX_NAME task_list
#endif
if (unlikely(!files->resize_wait.XXX_NAME.next)) {
files->resize_in_progress = false;
init_waitqueue_head(&files->resize_wait);
}
#endif
/* see f938612dd97d481b8b5bf960c992ae577f081c17
* and 1a7bd2265fc57f29400d57f66275cc5918e30aa6
*/
#if defined(get_unused_fd) || defined(get_unused_fd_flags)
err = get_unused_fd();
#else
err = get_unused_fd_flags(0);
#endif
mutex_unlock(&_fd_lock);
/* safety workaround: skip standard Unix filehandles */
} while (err >= 0 && err <= 2 && count++ < 3);
done:
return err;
}
static
int _create_ioctx(struct aio_output *output)
{
struct file *file;
mm_segment_t oldfs;
int err = -EINVAL;
CHECK_PTR_NULL(output, done);
CHECK_PTR_NULL(output->mf, done);
file = output->mf->mf_filp;
CHECK_PTR_NULL(file, done);
err = _get_fd();
MARS_DBG("file %p '%s' new fd = %d\n", file, output->mf->mf_name, err);
if (unlikely(err < 0)) {
MARS_ERR("cannot get fd, err=%d\n", err);
goto done;
}
output->fd = err;
fd_install(err, file);
use_fake_mm();
err = -ENOMEM;
if (unlikely(!current->mm)) {
MARS_ERR("cannot fake mm\n");
goto done;
}
#ifdef HAS_AIO_MAX
/* Self-tune aio_max_nr when possible. */
mutex_lock(&aio_max_lock);
aio_max_nr_current += MARS_MAX_AIO;
if (aio_max_nr_current > aio_max_nr_max) {
int diff = aio_max_nr_current - aio_max_nr_max;
aio_max_nr += diff;
aio_max_nr_max = aio_max_nr_current;
}
mutex_unlock(&aio_max_lock);
#endif
MARS_DBG("ioctx count = %d old = %p\n", atomic_read(&ioctx_count), (void*)output->ctxp);
output->ctxp = 0;
oldfs = get_fs();
set_fs(KERNEL_DS);
#ifdef MARS_HAS_PREPATCH_V2
err = ksys_io_setup(MARS_MAX_AIO, &output->ctxp);
#else
err = sys_io_setup(MARS_MAX_AIO, &output->ctxp);
#endif
set_fs(oldfs);
if (likely(output->ctxp))
atomic_inc(&ioctx_count);
MARS_DBG("ioctx count = %d new = %p status = %d\n", atomic_read(&ioctx_count), (void*)output->ctxp, err);
if (unlikely(err < 0)) {
MARS_ERR("io_setup failed, err=%d\n", err);
goto done;
}
err = aio_start_thread(output, &output->tinfo[1], aio_event_thread, 'e');
if (unlikely(err < 0)) {
MARS_ERR("could not start event thread\n");
goto done;
}
done:
if (likely(current->mm)) {
unuse_fake_mm();
}
return err;
}
static int aio_submit_thread(void *data)
{
struct aio_threadinfo *tinfo = data;
struct aio_output *output = tinfo->output;
struct file *file;
int err = -EINVAL;
MARS_DBG("submit thread has started.\n");
file = output->mf->mf_filp;
use_fake_mm();
while (!tinfo->should_terminate || atomic_read(&output->read_count) + atomic_read(&output->write_count) + atomic_read(&tinfo->queued_sum) > 0) {
struct aio_mref_aspect *mref_a;
struct mref_object *mref;
int sleeptime;
int status;
wait_event_interruptible_timeout(
tinfo->event,
atomic_read(&tinfo->queued_sum) > 0 ||
tinfo->should_terminate,
HZ / 4);
mref_a = _dequeue(tinfo);
if (!mref_a) {
continue;
}
mref = mref_a->object;
status = -EINVAL;
CHECK_PTR(mref, error);
mapfree_set(output->mf, mref->ref_pos, -1);
if (mref->ref_flags & MREF_WRITE) {
mf_dirty_append(output->mf, DIRTY_SUBMITTED, mref->ref_pos + mref->ref_len);
}
mref->ref_total_size = get_total_size(output);
/* Check for reads crossing the EOF boundary (special case)
*/
if (!(mref->ref_flags & MREF_WRITE) &&
mref->ref_pos + mref->ref_len > mref->ref_total_size) {
loff_t len;
/* Timeout handling, ONLY possible for reads
* beyond EOF.
* Currently not used! Needed for a future feature.
*/
if (mref->ref_timeout > 0) {
if (!mref_a->start_jiffies)
mref_a->start_jiffies = jiffies;
if ((long long)jiffies - mref_a->start_jiffies <= mref->ref_timeout) {
if (atomic_read(&tinfo->queued_sum) <= 0) {
#ifdef MARS_AIO_DEBUG
atomic_inc(&output->total_msleep_count);
#endif
brick_msleep(1000 * 4 / HZ);
}
_enqueue(tinfo, mref_a, MARS_PRIO_LOW, true);
continue;
}
MARS_DBG("ENODATA %lld\n", len);
_complete(output, mref_a, -ENODATA);
continue;
}
/* Shorten reads crossing EOF.
*/
len = mref->ref_total_size - mref->ref_pos;
if (len > 0 && mref->ref_len > len)
mref->ref_len = len;
}
sleeptime = 1;
for (;;) {
status = aio_submit(output, mref_a, false);
if (likely(status != -EAGAIN)) {
break;
}
#ifdef MARS_AIO_DEBUG
atomic_inc(&output->total_delay_count);
#endif
brick_msleep(sleeptime);
if (sleeptime < 100) {
sleeptime++;
}
}
error:
if (unlikely(status < 0)) {
MARS_IO("submit_count = %d status = %d\n", atomic_read(&output->submit_count), status);
_complete_mref(output, mref, status);
}
}
MARS_DBG("submit thread has stopped, status = %d.\n", err);
if (likely(current->mm)) {
unuse_fake_mm();
}
tinfo->terminated = true;
wake_up_interruptible_all(&tinfo->terminate_event);
return err;
}
static int aio_get_info(struct aio_output *output, struct mars_info *info)
{
struct file *file;
if (unlikely(!output ||
!output->mf ||
!(file = output->mf->mf_filp) ||
!file->f_mapping ||
!file->f_mapping->host))
return -EINVAL;
info->tf_align = 1;
info->tf_min_size = 1;
info->current_size = get_total_size(output);
MARS_DBG("determined file size = %lld\n", info->current_size);
return 0;
}
//////////////// informational / statistics ///////////////
static noinline
char *aio_statistics(struct aio_brick *brick, int verbose)
{
struct aio_output *output = brick->outputs[0];
char *res = brick_string_alloc(4096);
char *sync = NULL;
int pos = 0;
if (!res)
return NULL;
pos += report_timing(&timings[0], res + pos, 4096 - pos);
pos += report_timing(&timings[1], res + pos, 4096 - pos);
pos += report_timing(&timings[2], res + pos, 4096 - pos);
snprintf(res + pos, 4096 - pos,
#ifdef MARS_AIO_DEBUG
"total "
"reads = %d "
"writes = %d "
"allocs = %d "
"submits = %d "
"again = %d "
"delays = %d "
"msleeps = %d "
"fdsyncs = %d "
"fdsync_waits = %d "
"map_free = %d | "
#endif
"flying reads = %d "
"writes = %d "
#ifdef MARS_AIO_DEBUG
"allocs = %d "
#endif
"submits = %d "
"q0 = %d "
"q1 = %d "
"q2 = %d "
#ifdef MARS_AIO_DEBUG
"| total "
"q0 = %d "
"q1 = %d "
"q2 = %d "
#endif
"%s\n",
#ifdef MARS_AIO_DEBUG
atomic_read(&output->total_read_count),
atomic_read(&output->total_write_count),
atomic_read(&output->total_alloc_count),
atomic_read(&output->total_submit_count),
atomic_read(&output->total_again_count),
atomic_read(&output->total_delay_count),
atomic_read(&output->total_msleep_count),
atomic_read(&output->total_fdsync_count),
atomic_read(&output->total_fdsync_wait_count),
atomic_read(&output->total_mapfree_count),
#endif
atomic_read(&output->read_count),
atomic_read(&output->write_count),
#ifdef MARS_AIO_DEBUG
atomic_read(&output->alloc_count),
#endif
atomic_read(&output->submit_count),
atomic_read(&output->tinfo[0].queued_sum),
atomic_read(&output->tinfo[1].queued_sum),
atomic_read(&output->tinfo[2].queued_sum),
#ifdef MARS_AIO_DEBUG
atomic_read(&output->tinfo[0].total_enqueue_count),
atomic_read(&output->tinfo[1].total_enqueue_count),
atomic_read(&output->tinfo[2].total_enqueue_count),
#endif
sync ? sync : "");
brick_string_free(sync);
return res;
}
static noinline
void aio_reset_statistics(struct aio_brick *brick)
{
#ifdef MARS_AIO_DEBUG
struct aio_output *output = brick->outputs[0];
int i;
atomic_set(&output->total_read_count, 0);
atomic_set(&output->total_write_count, 0);
atomic_set(&output->total_alloc_count, 0);
atomic_set(&output->total_submit_count, 0);
atomic_set(&output->total_again_count, 0);
atomic_set(&output->total_delay_count, 0);
atomic_set(&output->total_msleep_count, 0);
atomic_set(&output->total_fdsync_count, 0);
atomic_set(&output->total_fdsync_wait_count, 0);
atomic_set(&output->total_mapfree_count, 0);
for (i = 0; i < 3; i++) {
struct aio_threadinfo *tinfo = &output->tinfo[i];
atomic_set(&tinfo->total_enqueue_count, 0);
}
#endif
}
#endif /* ENABLE_MARS_AIO */
//////////////// object / aspect constructors / destructors ///////////////
static int aio_mref_aspect_init_fn(struct generic_aspect *_ini)
{
struct aio_mref_aspect *ini = (void*)_ini;
INIT_LIST_HEAD(&ini->io_head);
return 0;
}
static void aio_mref_aspect_exit_fn(struct generic_aspect *_ini)
{
struct aio_mref_aspect *ini = (void*)_ini;
CHECK_HEAD_EMPTY(&ini->io_head);
}
MARS_MAKE_STATICS(aio);
#ifdef ENABLE_MARS_AIO
////////////////////// brick constructors / destructors ////////////////////
static int aio_brick_construct(struct aio_brick *brick)
{
return 0;
}
static int aio_switch(struct aio_brick *brick)
{
static int index;
struct aio_output *output = brick->outputs[0];
const char *path = output->brick->brick_path;
int flags = O_RDWR | O_LARGEFILE;
int status = 0;
MARS_DBG("power.button = %d\n", brick->power.button);
if (!brick->power.button)
goto cleanup;
if (brick->power.led_on || output->mf)
goto done;
mars_power_led_off((void*)brick, false);
flags |= O_LARGEFILE;
if (brick->o_creat) {
flags |= (O_NOFOLLOW | O_CREAT);
MARS_DBG("using O_CREAT on %s\n", path);
}
if (brick->o_direct) {
flags |= O_DIRECT;
MARS_DBG("using O_DIRECT on %s\n", path);
}
output->error = 0;
output->mf = mapfree_get(path, flags, &output->error);
if (unlikely(!output->mf)) {
MARS_ERR("could not open file = '%s' flags = %d error = %d\n",
path, flags, output->error);
status = output->error;
if (!status)
status = -ENOENT;
goto err;
}
output->index = ++index;
status = _create_ioctx(output);
if (unlikely(status < 0)) {
MARS_ERR("could not create ioctx, status = %d\n", status);
goto err;
}
status = aio_start_thread(output, &output->tinfo[0], aio_submit_thread, 's');
if (unlikely(status < 0)) {
MARS_ERR("could not start theads, status = %d\n", status);
goto err;
}
MARS_DBG("opened file '%s'\n", path);
brick->mode_ptr = &output->mf->mf_mode;
mars_power_led_on((void*)brick, true);
done:
return 0;
err:
MARS_ERR("status = %d\n", status);
cleanup:
if (brick->power.led_off) {
goto done;
}
mars_power_led_on((void*)brick, false);
for (;;) {
int count = atomic_read(&output->work_count);
if (count <= 0)
break;
MARS_DBG("working on %d requests\n", count);
brick_msleep(1000);
}
aio_stop_thread(output, 0, false);
brick->mode_ptr = NULL;
_destroy_ioctx(output);
mars_power_led_off((void*)brick,
(output->tinfo[0].thread == NULL &&
output->tinfo[1].thread == NULL &&
output->tinfo[2].thread == NULL));
MARS_DBG("switch off led_off = %d status = %d\n", brick->power.led_off, status);
if (brick->power.led_off) {
if (output->mf) {
MARS_DBG("closing file = '%s'\n", output->mf->mf_name);
mapfree_put(output->mf);
output->mf = NULL;
}
}
return status;
}
static int aio_output_construct(struct aio_output *output)
{
init_waitqueue_head(&output->fdsync_event);
output->fd = -1;
return 0;
}
static int aio_output_destruct(struct aio_output *output)
{
if (unlikely(output->fd >= 0)) {
MARS_ERR("active fd = %d detected\n", output->fd);
}
return 0;
}
///////////////////////// static structs ////////////////////////
static struct aio_brick_ops aio_brick_ops = {
.brick_switch = aio_switch,
.brick_statistics = aio_statistics,
.reset_statistics = aio_reset_statistics,
};
static struct aio_output_ops aio_output_ops = {
.mref_get = aio_ref_get,
.mref_put = aio_ref_put,
.mref_io = aio_ref_io,
.mars_get_info = aio_get_info,
};
const struct aio_input_type aio_input_type = {
.type_name = "aio_input",
.input_size = sizeof(struct aio_input),
};
static const struct aio_input_type *aio_input_types[] = {
&aio_input_type,
};
const struct aio_output_type aio_output_type = {
.type_name = "aio_output",
.output_size = sizeof(struct aio_output),
.master_ops = &aio_output_ops,
.output_construct = &aio_output_construct,
.output_destruct = &aio_output_destruct,
};
static const struct aio_output_type *aio_output_types[] = {
&aio_output_type,
};
#endif /* ENABLE_MARS_AIO */
const struct aio_brick_type aio_brick_type = {
.type_name = "aio_brick",
.brick_size = sizeof(struct aio_brick),
.max_inputs = 0,
.max_outputs = 1,
#ifdef ENABLE_MARS_AIO
.master_ops = &aio_brick_ops,
.aspect_types = aio_aspect_types,
.default_input_types = aio_input_types,
.default_output_types = aio_output_types,
.brick_construct = &aio_brick_construct,
#else /* ENABLE_MARS_AIO */
.aspect_types = aio_aspect_types, /* dummy, shut up gcc */
#endif /* ENABLE_MARS_AIO */
};
EXPORT_SYMBOL_GPL(aio_brick_type);
////////////////// module init stuff /////////////////////////
int __init init_mars_aio(void)
{
MARS_DBG("init_aio()\n");
_aio_brick_type = (void*)&aio_brick_type;
return aio_register_brick_type();
}
void exit_mars_aio(void)
{
MARS_DBG("exit_aio()\n");
aio_unregister_brick_type();
}
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