mirrors/qemu
0
0
Fork 0
mirror of https://github.com/qemu/qemu.git synced 2024-11-24 19:33:39 +08:00
Code Issues Packages Projects Releases Wiki Activity
cc1e139139
qemu/block/mirror.c
Eric Blake 67adf4b398 trace: Fix backwards mirror_yield parameters 
block/trace-events lists the parameters for mirror_yield
consistently with other mirror events (cnt just after s, like in
mirror_before_sleep; in_flight last, like in mirror_yield_in_flight).
But the callers were passing parameters in the wrong order, leading
to poor trace messages, including type truncation when there are
more than 4G dirty sectors involved.  Broken since its introduction
in commit bd48bde.

While touching this, ensure that all callers use the same type
(uint64_t) for cnt, as a later patch will enable the compiler to do
stricter type-checking.

Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-03-24 09:21:42 +00:00

1313 lines
44 KiB
C
Raw Blame History

/*
* Image mirroring
*
* Copyright Red Hat, Inc. 2012
*
* Authors:
* Paolo Bonzini <pbonzini@redhat.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include "qemu/cutils.h"
#include "trace.h"
#include "block/blockjob_int.h"
#include "block/block_int.h"
#include "sysemu/block-backend.h"
#include "qapi/error.h"
#include "qapi/qmp/qerror.h"
#include "qemu/ratelimit.h"
#include "qemu/bitmap.h"
#define SLICE_TIME 100000000ULL /* ns */
#define MAX_IN_FLIGHT 16
#define MAX_IO_SECTORS ((1 << 20) >> BDRV_SECTOR_BITS) /* 1 Mb */
#define DEFAULT_MIRROR_BUF_SIZE \
(MAX_IN_FLIGHT * MAX_IO_SECTORS * BDRV_SECTOR_SIZE)
/* The mirroring buffer is a list of granularity-sized chunks.
* Free chunks are organized in a list.
*/
typedef struct MirrorBuffer {
QSIMPLEQ_ENTRY(MirrorBuffer) next;
} MirrorBuffer;
typedef struct MirrorBlockJob {
BlockJob common;
RateLimit limit;
BlockBackend *target;
BlockDriverState *mirror_top_bs;
BlockDriverState *source;
BlockDriverState *base;
/* The name of the graph node to replace */
char *replaces;
/* The BDS to replace */
BlockDriverState *to_replace;
/* Used to block operations on the drive-mirror-replace target */
Error *replace_blocker;
bool is_none_mode;
BlockMirrorBackingMode backing_mode;
BlockdevOnError on_source_error, on_target_error;
bool synced;
bool should_complete;
int64_t granularity;
size_t buf_size;
int64_t bdev_length;
unsigned long *cow_bitmap;
BdrvDirtyBitmap *dirty_bitmap;
BdrvDirtyBitmapIter *dbi;
uint8_t *buf;
QSIMPLEQ_HEAD(, MirrorBuffer) buf_free;
int buf_free_count;
uint64_t last_pause_ns;
unsigned long *in_flight_bitmap;
int in_flight;
int64_t sectors_in_flight;
int ret;
bool unmap;
bool waiting_for_io;
int target_cluster_sectors;
int max_iov;
bool initial_zeroing_ongoing;
} MirrorBlockJob;
typedef struct MirrorOp {
MirrorBlockJob *s;
QEMUIOVector qiov;
int64_t sector_num;
int nb_sectors;
} MirrorOp;
static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read,
int error)
{
s->synced = false;
if (read) {
return block_job_error_action(&s->common, s->on_source_error,
true, error);
} else {
return block_job_error_action(&s->common, s->on_target_error,
false, error);
}
}
static void mirror_iteration_done(MirrorOp *op, int ret)
{
MirrorBlockJob *s = op->s;
struct iovec *iov;
int64_t chunk_num;
int i, nb_chunks, sectors_per_chunk;
trace_mirror_iteration_done(s, op->sector_num, op->nb_sectors, ret);
s->in_flight--;
s->sectors_in_flight -= op->nb_sectors;
iov = op->qiov.iov;
for (i = 0; i < op->qiov.niov; i++) {
MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base;
QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next);
s->buf_free_count++;
}
sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS;
chunk_num = op->sector_num / sectors_per_chunk;
nb_chunks = DIV_ROUND_UP(op->nb_sectors, sectors_per_chunk);
bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks);
if (ret >= 0) {
if (s->cow_bitmap) {
bitmap_set(s->cow_bitmap, chunk_num, nb_chunks);
}
if (!s->initial_zeroing_ongoing) {
s->common.offset += (uint64_t)op->nb_sectors * BDRV_SECTOR_SIZE;
}
}
qemu_iovec_destroy(&op->qiov);
g_free(op);
if (s->waiting_for_io) {
qemu_coroutine_enter(s->common.co);
}
}
static void mirror_write_complete(void *opaque, int ret)
{
MirrorOp *op = opaque;
MirrorBlockJob *s = op->s;
aio_context_acquire(blk_get_aio_context(s->common.blk));
if (ret < 0) {
BlockErrorAction action;
bdrv_set_dirty_bitmap(s->dirty_bitmap, op->sector_num, op->nb_sectors);
action = mirror_error_action(s, false, -ret);
if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) {
s->ret = ret;
}
}
mirror_iteration_done(op, ret);
aio_context_release(blk_get_aio_context(s->common.blk));
}
static void mirror_read_complete(void *opaque, int ret)
{
MirrorOp *op = opaque;
MirrorBlockJob *s = op->s;
aio_context_acquire(blk_get_aio_context(s->common.blk));
if (ret < 0) {
BlockErrorAction action;
bdrv_set_dirty_bitmap(s->dirty_bitmap, op->sector_num, op->nb_sectors);
action = mirror_error_action(s, true, -ret);
if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) {
s->ret = ret;
}
mirror_iteration_done(op, ret);
} else {
blk_aio_pwritev(s->target, op->sector_num * BDRV_SECTOR_SIZE, &op->qiov,
0, mirror_write_complete, op);
}
aio_context_release(blk_get_aio_context(s->common.blk));
}
static inline void mirror_clip_sectors(MirrorBlockJob *s,
int64_t sector_num,
int *nb_sectors)
{
*nb_sectors = MIN(*nb_sectors,
s->bdev_length / BDRV_SECTOR_SIZE - sector_num);
}
/* Round sector_num and/or nb_sectors to target cluster if COW is needed, and
* return the offset of the adjusted tail sector against original. */
static int mirror_cow_align(MirrorBlockJob *s,
int64_t *sector_num,
int *nb_sectors)
{
bool need_cow;
int ret = 0;
int chunk_sectors = s->granularity >> BDRV_SECTOR_BITS;
int64_t align_sector_num = *sector_num;
int align_nb_sectors = *nb_sectors;
int max_sectors = chunk_sectors * s->max_iov;
need_cow = !test_bit(*sector_num / chunk_sectors, s->cow_bitmap);
need_cow |= !test_bit((*sector_num + *nb_sectors - 1) / chunk_sectors,
s->cow_bitmap);
if (need_cow) {
bdrv_round_sectors_to_clusters(blk_bs(s->target), *sector_num,
*nb_sectors, &align_sector_num,
&align_nb_sectors);
}
if (align_nb_sectors > max_sectors) {
align_nb_sectors = max_sectors;
if (need_cow) {
align_nb_sectors = QEMU_ALIGN_DOWN(align_nb_sectors,
s->target_cluster_sectors);
}
}
/* Clipping may result in align_nb_sectors unaligned to chunk boundary, but
* that doesn't matter because it's already the end of source image. */
mirror_clip_sectors(s, align_sector_num, &align_nb_sectors);
ret = align_sector_num + align_nb_sectors - (*sector_num + *nb_sectors);
*sector_num = align_sector_num;
*nb_sectors = align_nb_sectors;
assert(ret >= 0);
return ret;
}
static inline void mirror_wait_for_io(MirrorBlockJob *s)
{
assert(!s->waiting_for_io);
s->waiting_for_io = true;
qemu_coroutine_yield();
s->waiting_for_io = false;
}
/* Submit async read while handling COW.
* Returns: The number of sectors copied after and including sector_num,
* excluding any sectors copied prior to sector_num due to alignment.
* This will be nb_sectors if no alignment is necessary, or
* (new_end - sector_num) if tail is rounded up or down due to
* alignment or buffer limit.
*/
static int mirror_do_read(MirrorBlockJob *s, int64_t sector_num,
int nb_sectors)
{
BlockBackend *source = s->common.blk;
int sectors_per_chunk, nb_chunks;
int ret;
MirrorOp *op;
int max_sectors;
sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS;
max_sectors = sectors_per_chunk * s->max_iov;
/* We can only handle as much as buf_size at a time. */
nb_sectors = MIN(s->buf_size >> BDRV_SECTOR_BITS, nb_sectors);
nb_sectors = MIN(max_sectors, nb_sectors);
assert(nb_sectors);
ret = nb_sectors;
if (s->cow_bitmap) {
ret += mirror_cow_align(s, &sector_num, &nb_sectors);
}
assert(nb_sectors << BDRV_SECTOR_BITS <= s->buf_size);
/* The sector range must meet granularity because:
* 1) Caller passes in aligned values;
* 2) mirror_cow_align is used only when target cluster is larger. */
assert(!(sector_num % sectors_per_chunk));
nb_chunks = DIV_ROUND_UP(nb_sectors, sectors_per_chunk);
while (s->buf_free_count < nb_chunks) {
trace_mirror_yield_in_flight(s, sector_num, s->in_flight);
mirror_wait_for_io(s);
}
/* Allocate a MirrorOp that is used as an AIO callback. */
op = g_new(MirrorOp, 1);
op->s = s;
op->sector_num = sector_num;
op->nb_sectors = nb_sectors;
/* Now make a QEMUIOVector taking enough granularity-sized chunks
* from s->buf_free.
*/
qemu_iovec_init(&op->qiov, nb_chunks);
while (nb_chunks-- > 0) {
MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free);
size_t remaining = nb_sectors * BDRV_SECTOR_SIZE - op->qiov.size;
QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next);
s->buf_free_count--;
qemu_iovec_add(&op->qiov, buf, MIN(s->granularity, remaining));
}
/* Copy the dirty cluster. */
s->in_flight++;
s->sectors_in_flight += nb_sectors;
trace_mirror_one_iteration(s, sector_num, nb_sectors);
blk_aio_preadv(source, sector_num * BDRV_SECTOR_SIZE, &op->qiov, 0,
mirror_read_complete, op);
return ret;
}
static void mirror_do_zero_or_discard(MirrorBlockJob *s,
int64_t sector_num,
int nb_sectors,
bool is_discard)
{
MirrorOp *op;
/* Allocate a MirrorOp that is used as an AIO callback. The qiov is zeroed
* so the freeing in mirror_iteration_done is nop. */
op = g_new0(MirrorOp, 1);
op->s = s;
op->sector_num = sector_num;
op->nb_sectors = nb_sectors;
s->in_flight++;
s->sectors_in_flight += nb_sectors;
if (is_discard) {
blk_aio_pdiscard(s->target, sector_num << BDRV_SECTOR_BITS,
op->nb_sectors << BDRV_SECTOR_BITS,
mirror_write_complete, op);
} else {
blk_aio_pwrite_zeroes(s->target, sector_num * BDRV_SECTOR_SIZE,
op->nb_sectors * BDRV_SECTOR_SIZE,
s->unmap ? BDRV_REQ_MAY_UNMAP : 0,
mirror_write_complete, op);
}
}
static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
{
BlockDriverState *source = s->source;
int64_t sector_num, first_chunk;
uint64_t delay_ns = 0;
/* At least the first dirty chunk is mirrored in one iteration. */
int nb_chunks = 1;
int64_t end = s->bdev_length / BDRV_SECTOR_SIZE;
int sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS;
bool write_zeroes_ok = bdrv_can_write_zeroes_with_unmap(blk_bs(s->target));
int max_io_sectors = MAX((s->buf_size >> BDRV_SECTOR_BITS) / MAX_IN_FLIGHT,
MAX_IO_SECTORS);
sector_num = bdrv_dirty_iter_next(s->dbi);
if (sector_num < 0) {
bdrv_set_dirty_iter(s->dbi, 0);
sector_num = bdrv_dirty_iter_next(s->dbi);
trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap));
assert(sector_num >= 0);
}
first_chunk = sector_num / sectors_per_chunk;
while (test_bit(first_chunk, s->in_flight_bitmap)) {
trace_mirror_yield_in_flight(s, sector_num, s->in_flight);
mirror_wait_for_io(s);
}
block_job_pause_point(&s->common);
/* Find the number of consective dirty chunks following the first dirty
* one, and wait for in flight requests in them. */
while (nb_chunks * sectors_per_chunk < (s->buf_size >> BDRV_SECTOR_BITS)) {
int64_t next_dirty;
int64_t next_sector = sector_num + nb_chunks * sectors_per_chunk;
int64_t next_chunk = next_sector / sectors_per_chunk;
if (next_sector >= end ||
!bdrv_get_dirty(source, s->dirty_bitmap, next_sector)) {
break;
}
if (test_bit(next_chunk, s->in_flight_bitmap)) {
break;
}
next_dirty = bdrv_dirty_iter_next(s->dbi);
if (next_dirty > next_sector || next_dirty < 0) {
/* The bitmap iterator's cache is stale, refresh it */
bdrv_set_dirty_iter(s->dbi, next_sector);
next_dirty = bdrv_dirty_iter_next(s->dbi);
}
assert(next_dirty == next_sector);
nb_chunks++;
}
/* Clear dirty bits before querying the block status, because
* calling bdrv_get_block_status_above could yield - if some blocks are
* marked dirty in this window, we need to know.
*/
bdrv_reset_dirty_bitmap(s->dirty_bitmap, sector_num,
nb_chunks * sectors_per_chunk);
bitmap_set(s->in_flight_bitmap, sector_num / sectors_per_chunk, nb_chunks);
while (nb_chunks > 0 && sector_num < end) {
int64_t ret;
int io_sectors, io_sectors_acct;
BlockDriverState *file;
enum MirrorMethod {
MIRROR_METHOD_COPY,
MIRROR_METHOD_ZERO,
MIRROR_METHOD_DISCARD
} mirror_method = MIRROR_METHOD_COPY;
assert(!(sector_num % sectors_per_chunk));
ret = bdrv_get_block_status_above(source, NULL, sector_num,
nb_chunks * sectors_per_chunk,
&io_sectors, &file);
if (ret < 0) {
io_sectors = MIN(nb_chunks * sectors_per_chunk, max_io_sectors);
} else if (ret & BDRV_BLOCK_DATA) {
io_sectors = MIN(io_sectors, max_io_sectors);
}
io_sectors -= io_sectors % sectors_per_chunk;
if (io_sectors < sectors_per_chunk) {
io_sectors = sectors_per_chunk;
} else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) {
int64_t target_sector_num;
int target_nb_sectors;
bdrv_round_sectors_to_clusters(blk_bs(s->target), sector_num,
io_sectors, &target_sector_num,
&target_nb_sectors);
if (target_sector_num == sector_num &&
target_nb_sectors == io_sectors) {
mirror_method = ret & BDRV_BLOCK_ZERO ?
MIRROR_METHOD_ZERO :
MIRROR_METHOD_DISCARD;
}
}
while (s->in_flight >= MAX_IN_FLIGHT) {
trace_mirror_yield_in_flight(s, sector_num, s->in_flight);
mirror_wait_for_io(s);
}
if (s->ret < 0) {
return 0;
}
mirror_clip_sectors(s, sector_num, &io_sectors);
switch (mirror_method) {
case MIRROR_METHOD_COPY:
io_sectors = mirror_do_read(s, sector_num, io_sectors);
io_sectors_acct = io_sectors;
break;
case MIRROR_METHOD_ZERO:
case MIRROR_METHOD_DISCARD:
mirror_do_zero_or_discard(s, sector_num, io_sectors,
mirror_method == MIRROR_METHOD_DISCARD);
if (write_zeroes_ok) {
io_sectors_acct = 0;
} else {
io_sectors_acct = io_sectors;
}
break;
default:
abort();
}
assert(io_sectors);
sector_num += io_sectors;
nb_chunks -= DIV_ROUND_UP(io_sectors, sectors_per_chunk);
if (s->common.speed) {
delay_ns = ratelimit_calculate_delay(&s->limit, io_sectors_acct);
}
}
return delay_ns;
}
static void mirror_free_init(MirrorBlockJob *s)
{
int granularity = s->granularity;
size_t buf_size = s->buf_size;
uint8_t *buf = s->buf;
assert(s->buf_free_count == 0);
QSIMPLEQ_INIT(&s->buf_free);
while (buf_size != 0) {
MirrorBuffer *cur = (MirrorBuffer *)buf;
QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next);
s->buf_free_count++;
buf_size -= granularity;
buf += granularity;
}
}
/* This is also used for the .pause callback. There is no matching
* mirror_resume() because mirror_run() will begin iterating again
* when the job is resumed.
*/
static void mirror_wait_for_all_io(MirrorBlockJob *s)
{
while (s->in_flight > 0) {
mirror_wait_for_io(s);
}
}
typedef struct {
int ret;
} MirrorExitData;
static void mirror_exit(BlockJob *job, void *opaque)
{
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
MirrorExitData *data = opaque;
AioContext *replace_aio_context = NULL;
BlockDriverState *src = s->source;
BlockDriverState *target_bs = blk_bs(s->target);
BlockDriverState *mirror_top_bs = s->mirror_top_bs;
Error *local_err = NULL;
/* Make sure that the source BDS doesn't go away before we called
* block_job_completed(). */
bdrv_ref(src);
bdrv_ref(mirror_top_bs);
bdrv_ref(target_bs);
/* Remove target parent that still uses BLK_PERM_WRITE/RESIZE before
* inserting target_bs at s->to_replace, where we might not be able to get
* these permissions. */
blk_unref(s->target);
s->target = NULL;
/* We don't access the source any more. Dropping any WRITE/RESIZE is
* required before it could become a backing file of target_bs. */
bdrv_child_try_set_perm(mirror_top_bs->backing, 0, BLK_PERM_ALL,
&error_abort);
if (s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) {
BlockDriverState *backing = s->is_none_mode ? src : s->base;
if (backing_bs(target_bs) != backing) {
bdrv_set_backing_hd(target_bs, backing, &local_err);
if (local_err) {
error_report_err(local_err);
data->ret = -EPERM;
}
}
}
if (s->to_replace) {
replace_aio_context = bdrv_get_aio_context(s->to_replace);
aio_context_acquire(replace_aio_context);
}
if (s->should_complete && data->ret == 0) {
BlockDriverState *to_replace = src;
if (s->to_replace) {
to_replace = s->to_replace;
}
if (bdrv_get_flags(target_bs) != bdrv_get_flags(to_replace)) {
bdrv_reopen(target_bs, bdrv_get_flags(to_replace), NULL);
}
/* The mirror job has no requests in flight any more, but we need to
* drain potential other users of the BDS before changing the graph. */
bdrv_drained_begin(target_bs);
bdrv_replace_node(to_replace, target_bs, &local_err);
bdrv_drained_end(target_bs);
if (local_err) {
error_report_err(local_err);
data->ret = -EPERM;
}
}
if (s->to_replace) {
bdrv_op_unblock_all(s->to_replace, s->replace_blocker);
error_free(s->replace_blocker);
bdrv_unref(s->to_replace);
}
if (replace_aio_context) {
aio_context_release(replace_aio_context);
}
g_free(s->replaces);
bdrv_unref(target_bs);
/* Remove the mirror filter driver from the graph. Before this, get rid of
* the blockers on the intermediate nodes so that the resulting state is
* valid. Also give up permissions on mirror_top_bs->backing, which might
* block the removal. */
block_job_remove_all_bdrv(job);
bdrv_child_try_set_perm(mirror_top_bs->backing, 0, BLK_PERM_ALL,
&error_abort);
bdrv_replace_node(mirror_top_bs, backing_bs(mirror_top_bs), &error_abort);
/* We just changed the BDS the job BB refers to (with either or both of the
* bdrv_replace_node() calls), so switch the BB back so the cleanup does
* the right thing. We don't need any permissions any more now. */
blk_remove_bs(job->blk);
blk_set_perm(job->blk, 0, BLK_PERM_ALL, &error_abort);
blk_insert_bs(job->blk, mirror_top_bs, &error_abort);
block_job_completed(&s->common, data->ret);
g_free(data);
bdrv_drained_end(src);
bdrv_unref(mirror_top_bs);
bdrv_unref(src);
}
static void mirror_throttle(MirrorBlockJob *s)
{
int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
if (now - s->last_pause_ns > SLICE_TIME) {
s->last_pause_ns = now;
block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, 0);
} else {
block_job_pause_point(&s->common);
}
}
static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
{
int64_t sector_num, end;
BlockDriverState *base = s->base;
BlockDriverState *bs = s->source;
BlockDriverState *target_bs = blk_bs(s->target);
int ret, n;
end = s->bdev_length / BDRV_SECTOR_SIZE;
if (base == NULL && !bdrv_has_zero_init(target_bs)) {
if (!bdrv_can_write_zeroes_with_unmap(target_bs)) {
bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, end);
return 0;
}
s->initial_zeroing_ongoing = true;
for (sector_num = 0; sector_num < end; ) {
int nb_sectors = MIN(end - sector_num,
QEMU_ALIGN_DOWN(INT_MAX, s->granularity) >> BDRV_SECTOR_BITS);
mirror_throttle(s);
if (block_job_is_cancelled(&s->common)) {
s->initial_zeroing_ongoing = false;
return 0;
}
if (s->in_flight >= MAX_IN_FLIGHT) {
trace_mirror_yield(s, UINT64_MAX, s->buf_free_count,
s->in_flight);
mirror_wait_for_io(s);
continue;
}
mirror_do_zero_or_discard(s, sector_num, nb_sectors, false);
sector_num += nb_sectors;
}
mirror_wait_for_all_io(s);
s->initial_zeroing_ongoing = false;
}
/* First part, loop on the sectors and initialize the dirty bitmap. */
for (sector_num = 0; sector_num < end; ) {
/* Just to make sure we are not exceeding int limit. */
int nb_sectors = MIN(INT_MAX >> BDRV_SECTOR_BITS,
end - sector_num);
mirror_throttle(s);
if (block_job_is_cancelled(&s->common)) {
return 0;
}
ret = bdrv_is_allocated_above(bs, base, sector_num, nb_sectors, &n);
if (ret < 0) {
return ret;
}
assert(n > 0);
if (ret == 1) {
bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n);
}
sector_num += n;
}
return 0;
}
/* Called when going out of the streaming phase to flush the bulk of the
* data to the medium, or just before completing.
*/
static int mirror_flush(MirrorBlockJob *s)
{
int ret = blk_flush(s->target);
if (ret < 0) {
if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) {
s->ret = ret;
}
}
return ret;
}
static void coroutine_fn mirror_run(void *opaque)
{
MirrorBlockJob *s = opaque;
MirrorExitData *data;
BlockDriverState *bs = s->source;
BlockDriverState *target_bs = blk_bs(s->target);
bool need_drain = true;
int64_t length;
BlockDriverInfo bdi;
char backing_filename[2]; /* we only need 2 characters because we are only
checking for a NULL string */
int ret = 0;
int target_cluster_size = BDRV_SECTOR_SIZE;
if (block_job_is_cancelled(&s->common)) {
goto immediate_exit;
}
s->bdev_length = bdrv_getlength(bs);
if (s->bdev_length < 0) {
ret = s->bdev_length;
goto immediate_exit;
}
/* Active commit must resize the base image if its size differs from the
* active layer. */
if (s->base == blk_bs(s->target)) {
int64_t base_length;
base_length = blk_getlength(s->target);
if (base_length < 0) {
ret = base_length;
goto immediate_exit;
}
if (s->bdev_length > base_length) {
ret = blk_truncate(s->target, s->bdev_length);
if (ret < 0) {
goto immediate_exit;
}
}
}
if (s->bdev_length == 0) {
/* Report BLOCK_JOB_READY and wait for complete. */
block_job_event_ready(&s->common);
s->synced = true;
while (!block_job_is_cancelled(&s->common) && !s->should_complete) {
block_job_yield(&s->common);
}
s->common.cancelled = false;
goto immediate_exit;
}
length = DIV_ROUND_UP(s->bdev_length, s->granularity);
s->in_flight_bitmap = bitmap_new(length);
/* If we have no backing file yet in the destination, we cannot let
* the destination do COW. Instead, we copy sectors around the
* dirty data if needed. We need a bitmap to do that.
*/
bdrv_get_backing_filename(target_bs, backing_filename,
sizeof(backing_filename));
if (!bdrv_get_info(target_bs, &bdi) && bdi.cluster_size) {
target_cluster_size = bdi.cluster_size;
}
if (backing_filename[0] && !target_bs->backing
&& s->granularity < target_cluster_size) {
s->buf_size = MAX(s->buf_size, target_cluster_size);
s->cow_bitmap = bitmap_new(length);
}
s->target_cluster_sectors = target_cluster_size >> BDRV_SECTOR_BITS;
s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov);
s->buf = qemu_try_blockalign(bs, s->buf_size);
if (s->buf == NULL) {
ret = -ENOMEM;
goto immediate_exit;
}
mirror_free_init(s);
s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
if (!s->is_none_mode) {
ret = mirror_dirty_init(s);
if (ret < 0 || block_job_is_cancelled(&s->common)) {
goto immediate_exit;
}
}
assert(!s->dbi);
s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap, 0);
for (;;) {
uint64_t delay_ns = 0;
int64_t cnt, delta;
bool should_complete;
if (s->ret < 0) {
ret = s->ret;
goto immediate_exit;
}
block_job_pause_point(&s->common);
cnt = bdrv_get_dirty_count(s->dirty_bitmap);
/* s->common.offset contains the number of bytes already processed so
* far, cnt is the number of dirty sectors remaining and
* s->sectors_in_flight is the number of sectors currently being
* processed; together those are the current total operation length */
s->common.len = s->common.offset +
(cnt + s->sectors_in_flight) * BDRV_SECTOR_SIZE;
/* Note that even when no rate limit is applied we need to yield
* periodically with no pending I/O so that bdrv_drain_all() returns.
* We do so every SLICE_TIME nanoseconds, or when there is an error,
* or when the source is clean, whichever comes first.
*/
delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns;
if (delta < SLICE_TIME &&
s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 ||
(cnt == 0 && s->in_flight > 0)) {
trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight);
mirror_wait_for_io(s);
continue;
} else if (cnt != 0) {
delay_ns = mirror_iteration(s);
}
}
should_complete = false;
if (s->in_flight == 0 && cnt == 0) {
trace_mirror_before_flush(s);
if (!s->synced) {
if (mirror_flush(s) < 0) {
/* Go check s->ret. */
continue;
}
/* We're out of the streaming phase. From now on, if the job
* is cancelled we will actually complete all pending I/O and
* report completion. This way, block-job-cancel will leave
* the target in a consistent state.
*/
block_job_event_ready(&s->common);
s->synced = true;
}
should_complete = s->should_complete ||
block_job_is_cancelled(&s->common);
cnt = bdrv_get_dirty_count(s->dirty_bitmap);
}
if (cnt == 0 && should_complete) {
/* The dirty bitmap is not updated while operations are pending.
* If we're about to exit, wait for pending operations before
* calling bdrv_get_dirty_count(bs), or we may exit while the
* source has dirty data to copy!
*
* Note that I/O can be submitted by the guest while
* mirror_populate runs, so pause it now. Before deciding
* whether to switch to target check one last time if I/O has
* come in the meanwhile, and if not flush the data to disk.
*/
trace_mirror_before_drain(s, cnt);
bdrv_drained_begin(bs);
cnt = bdrv_get_dirty_count(s->dirty_bitmap);
if (cnt > 0 || mirror_flush(s) < 0) {
bdrv_drained_end(bs);
continue;
}
/* The two disks are in sync. Exit and report successful
* completion.
*/
assert(QLIST_EMPTY(&bs->tracked_requests));
s->common.cancelled = false;
need_drain = false;
break;
}
ret = 0;
trace_mirror_before_sleep(s, cnt, s->synced, delay_ns);
if (!s->synced) {
block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns);
if (block_job_is_cancelled(&s->common)) {
break;
}
} else if (!should_complete) {
delay_ns = (s->in_flight == 0 && cnt == 0 ? SLICE_TIME : 0);
block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns);
}
s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
}
immediate_exit:
if (s->in_flight > 0) {
/* We get here only if something went wrong. Either the job failed,
* or it was cancelled prematurely so that we do not guarantee that
* the target is a copy of the source.
*/
assert(ret < 0 || (!s->synced && block_job_is_cancelled(&s->common)));
assert(need_drain);
mirror_wait_for_all_io(s);
}
assert(s->in_flight == 0);
qemu_vfree(s->buf);
g_free(s->cow_bitmap);
g_free(s->in_flight_bitmap);
bdrv_dirty_iter_free(s->dbi);
bdrv_release_dirty_bitmap(bs, s->dirty_bitmap);
data = g_malloc(sizeof(*data));
data->ret = ret;
if (need_drain) {
bdrv_drained_begin(bs);
}
block_job_defer_to_main_loop(&s->common, mirror_exit, data);
}
static void mirror_set_speed(BlockJob *job, int64_t speed, Error **errp)
{
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
if (speed < 0) {
error_setg(errp, QERR_INVALID_PARAMETER, "speed");
return;
}
ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME);
}
static void mirror_complete(BlockJob *job, Error **errp)
{
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
BlockDriverState *target;
target = blk_bs(s->target);
if (!s->synced) {
error_setg(errp, "The active block job '%s' cannot be completed",
job->id);
return;
}
if (s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) {
int ret;
assert(!target->backing);
ret = bdrv_open_backing_file(target, NULL, "backing", errp);
if (ret < 0) {
return;
}
}
/* block all operations on to_replace bs */
if (s->replaces) {
AioContext *replace_aio_context;
s->to_replace = bdrv_find_node(s->replaces);
if (!s->to_replace) {
error_setg(errp, "Node name '%s' not found", s->replaces);
return;
}
replace_aio_context = bdrv_get_aio_context(s->to_replace);
aio_context_acquire(replace_aio_context);
/* TODO Translate this into permission system. Current definition of
* GRAPH_MOD would require to request it for the parents; they might
* not even be BlockDriverStates, however, so a BdrvChild can't address
* them. May need redefinition of GRAPH_MOD. */
error_setg(&s->replace_blocker,
"block device is in use by block-job-complete");
bdrv_op_block_all(s->to_replace, s->replace_blocker);
bdrv_ref(s->to_replace);
aio_context_release(replace_aio_context);
}
s->should_complete = true;
block_job_enter(&s->common);
}
static void mirror_pause(BlockJob *job)
{
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
mirror_wait_for_all_io(s);
}
static void mirror_attached_aio_context(BlockJob *job, AioContext *new_context)
{
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
blk_set_aio_context(s->target, new_context);
}
static void mirror_drain(BlockJob *job)
{
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
/* Need to keep a reference in case blk_drain triggers execution
* of mirror_complete...
*/
if (s->target) {
BlockBackend *target = s->target;
blk_ref(target);
blk_drain(target);
blk_unref(target);
}
}
static const BlockJobDriver mirror_job_driver = {
.instance_size = sizeof(MirrorBlockJob),
.job_type = BLOCK_JOB_TYPE_MIRROR,
.set_speed = mirror_set_speed,
.start = mirror_run,
.complete = mirror_complete,
.pause = mirror_pause,
.attached_aio_context = mirror_attached_aio_context,
.drain = mirror_drain,
};
static const BlockJobDriver commit_active_job_driver = {
.instance_size = sizeof(MirrorBlockJob),
.job_type = BLOCK_JOB_TYPE_COMMIT,
.set_speed = mirror_set_speed,
.start = mirror_run,
.complete = mirror_complete,
.pause = mirror_pause,
.attached_aio_context = mirror_attached_aio_context,
.drain = mirror_drain,
};
static int coroutine_fn bdrv_mirror_top_preadv(BlockDriverState *bs,
uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags)
{
return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags);
}
static int coroutine_fn bdrv_mirror_top_pwritev(BlockDriverState *bs,
uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags)
{
return bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags);
}
static int coroutine_fn bdrv_mirror_top_flush(BlockDriverState *bs)
{
return bdrv_co_flush(bs->backing->bs);
}
static int64_t coroutine_fn bdrv_mirror_top_get_block_status(
BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum,
BlockDriverState **file)
{
*pnum = nb_sectors;
*file = bs->backing->bs;
return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID | BDRV_BLOCK_DATA |
(sector_num << BDRV_SECTOR_BITS);
}
static int coroutine_fn bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs,
int64_t offset, int count, BdrvRequestFlags flags)
{
return bdrv_co_pwrite_zeroes(bs->backing, offset, count, flags);
}
static int coroutine_fn bdrv_mirror_top_pdiscard(BlockDriverState *bs,
int64_t offset, int count)
{
return bdrv_co_pdiscard(bs->backing->bs, offset, count);
}
static void bdrv_mirror_top_refresh_filename(BlockDriverState *bs, QDict *opts)
{
bdrv_refresh_filename(bs->backing->bs);
pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
bs->backing->bs->filename);
}
static void bdrv_mirror_top_close(BlockDriverState *bs)
{
}
static void bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c,
const BdrvChildRole *role,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
/* Must be able to forward guest writes to the real image */
*nperm = 0;
if (perm & BLK_PERM_WRITE) {
*nperm |= BLK_PERM_WRITE;
}
*nshared = BLK_PERM_ALL;
}
/* Dummy node that provides consistent read to its users without requiring it
* from its backing file and that allows writes on the backing file chain. */
static BlockDriver bdrv_mirror_top = {
.format_name = "mirror_top",
.bdrv_co_preadv = bdrv_mirror_top_preadv,
.bdrv_co_pwritev = bdrv_mirror_top_pwritev,
.bdrv_co_pwrite_zeroes = bdrv_mirror_top_pwrite_zeroes,
.bdrv_co_pdiscard = bdrv_mirror_top_pdiscard,
.bdrv_co_flush = bdrv_mirror_top_flush,
.bdrv_co_get_block_status = bdrv_mirror_top_get_block_status,
.bdrv_refresh_filename = bdrv_mirror_top_refresh_filename,
.bdrv_close = bdrv_mirror_top_close,
.bdrv_child_perm = bdrv_mirror_top_child_perm,
};
static void mirror_start_job(const char *job_id, BlockDriverState *bs,
int creation_flags, BlockDriverState *target,
const char *replaces, int64_t speed,
uint32_t granularity, int64_t buf_size,
BlockMirrorBackingMode backing_mode,
BlockdevOnError on_source_error,
BlockdevOnError on_target_error,
bool unmap,
BlockCompletionFunc *cb,
void *opaque, Error **errp,
const BlockJobDriver *driver,
bool is_none_mode, BlockDriverState *base,
bool auto_complete, const char *filter_node_name)
{
MirrorBlockJob *s;
BlockDriverState *mirror_top_bs;
bool target_graph_mod;
bool target_is_backing;
Error *local_err = NULL;
int ret;
if (granularity == 0) {
granularity = bdrv_get_default_bitmap_granularity(target);
}
assert ((granularity & (granularity - 1)) == 0);
if (buf_size < 0) {
error_setg(errp, "Invalid parameter 'buf-size'");
return;
}
if (buf_size == 0) {
buf_size = DEFAULT_MIRROR_BUF_SIZE;
}
/* In the case of active commit, add dummy driver to provide consistent
* reads on the top, while disabling it in the intermediate nodes, and make
* the backing chain writable. */
mirror_top_bs = bdrv_new_open_driver(&bdrv_mirror_top, filter_node_name,
BDRV_O_RDWR, errp);
if (mirror_top_bs == NULL) {
return;
}
mirror_top_bs->total_sectors = bs->total_sectors;
/* bdrv_append takes ownership of the mirror_top_bs reference, need to keep
* it alive until block_job_create() even if bs has no parent. */
bdrv_ref(mirror_top_bs);
bdrv_drained_begin(bs);
bdrv_append(mirror_top_bs, bs, &local_err);
bdrv_drained_end(bs);
if (local_err) {
bdrv_unref(mirror_top_bs);
error_propagate(errp, local_err);
return;
}
/* Make sure that the source is not resized while the job is running */
s = block_job_create(job_id, driver, mirror_top_bs,
BLK_PERM_CONSISTENT_READ,
BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD, speed,
creation_flags, cb, opaque, errp);
bdrv_unref(mirror_top_bs);
if (!s) {
goto fail;
}
s->source = bs;
s->mirror_top_bs = mirror_top_bs;
/* No resize for the target either; while the mirror is still running, a
* consistent read isn't necessarily possible. We could possibly allow
* writes and graph modifications, though it would likely defeat the
* purpose of a mirror, so leave them blocked for now.
*
* In the case of active commit, things look a bit different, though,
* because the target is an already populated backing file in active use.
* We can allow anything except resize there.*/
target_is_backing = bdrv_chain_contains(bs, target);
target_graph_mod = (backing_mode != MIRROR_LEAVE_BACKING_CHAIN);
s->target = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE |
(target_graph_mod ? BLK_PERM_GRAPH_MOD : 0),
BLK_PERM_WRITE_UNCHANGED |
(target_is_backing ? BLK_PERM_CONSISTENT_READ |
BLK_PERM_WRITE |
BLK_PERM_GRAPH_MOD : 0));
ret = blk_insert_bs(s->target, target, errp);
if (ret < 0) {
goto fail;
}
s->replaces = g_strdup(replaces);
s->on_source_error = on_source_error;
s->on_target_error = on_target_error;
s->is_none_mode = is_none_mode;
s->backing_mode = backing_mode;
s->base = base;
s->granularity = granularity;
s->buf_size = ROUND_UP(buf_size, granularity);
s->unmap = unmap;
if (auto_complete) {
s->should_complete = true;
}
s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp);
if (!s->dirty_bitmap) {
goto fail;
}
/* Required permissions are already taken with blk_new() */
block_job_add_bdrv(&s->common, "target", target, 0, BLK_PERM_ALL,
&error_abort);
/* In commit_active_start() all intermediate nodes disappear, so
* any jobs in them must be blocked */
if (target_is_backing) {
BlockDriverState *iter;
for (iter = backing_bs(bs); iter != target; iter = backing_bs(iter)) {
/* XXX BLK_PERM_WRITE needs to be allowed so we don't block
* ourselves at s->base (if writes are blocked for a node, they are
* also blocked for its backing file). The other options would be a
* second filter driver above s->base (== target). */
ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE,
errp);
if (ret < 0) {
goto fail;
}
}
}
trace_mirror_start(bs, s, opaque);
block_job_start(&s->common);
return;
fail:
if (s) {
g_free(s->replaces);
blk_unref(s->target);
block_job_unref(&s->common);
}
bdrv_child_try_set_perm(mirror_top_bs->backing, 0, BLK_PERM_ALL,
&error_abort);
bdrv_replace_node(mirror_top_bs, backing_bs(mirror_top_bs), &error_abort);
}
void mirror_start(const char *job_id, BlockDriverState *bs,
BlockDriverState *target, const char *replaces,
int64_t speed, uint32_t granularity, int64_t buf_size,
MirrorSyncMode mode, BlockMirrorBackingMode backing_mode,
BlockdevOnError on_source_error,
BlockdevOnError on_target_error,
bool unmap, const char *filter_node_name, Error **errp)
{
bool is_none_mode;
BlockDriverState *base;
if (mode == MIRROR_SYNC_MODE_INCREMENTAL) {
error_setg(errp, "Sync mode 'incremental' not supported");
return;
}
is_none_mode = mode == MIRROR_SYNC_MODE_NONE;
base = mode == MIRROR_SYNC_MODE_TOP ? backing_bs(bs) : NULL;
mirror_start_job(job_id, bs, BLOCK_JOB_DEFAULT, target, replaces,
speed, granularity, buf_size, backing_mode,
on_source_error, on_target_error, unmap, NULL, NULL, errp,
&mirror_job_driver, is_none_mode, base, false,
filter_node_name);
}
void commit_active_start(const char *job_id, BlockDriverState *bs,
BlockDriverState *base, int creation_flags,
int64_t speed, BlockdevOnError on_error,
const char *filter_node_name,
BlockCompletionFunc *cb, void *opaque, Error **errp,
bool auto_complete)
{
int orig_base_flags;
Error *local_err = NULL;
orig_base_flags = bdrv_get_flags(base);
if (bdrv_reopen(base, bs->open_flags, errp)) {
return;
}
mirror_start_job(job_id, bs, creation_flags, base, NULL, speed, 0, 0,
MIRROR_LEAVE_BACKING_CHAIN,
on_error, on_error, true, cb, opaque, &local_err,
&commit_active_job_driver, false, base, auto_complete,
filter_node_name);
if (local_err) {
error_propagate(errp, local_err);
goto error_restore_flags;
}
return;
error_restore_flags:
/* ignore error and errp for bdrv_reopen, because we want to propagate
* the original error */
bdrv_reopen(base, orig_base_flags, NULL);
return;
}
Reference in New Issue View Git Blame Copy Permalink