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mirror: Switch mirror_iteration() to byte-based

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We are gradually converting to byte-based interfaces, as they are
easier to reason about than sector-based.  Change the internal
loop iteration of mirroring to track by bytes instead of sectors
(although we are still guaranteed that we iterate by steps that
are both sector-aligned and multiples of the granularity).  Drop
the now-unused mirror_clip_sectors().

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake 2017-07-07 07:44:51 -05:00 committed by Kevin Wolf
parent ae4cc8777b
commit fb2ef7919b
1 changed files with 46 additions and 59 deletions
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105
block/mirror.c
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@ -184,15 +184,6 @@ static inline int64_t mirror_clip_bytes(MirrorBlockJob *s,
return MIN(bytes, s->bdev_length - offset);
}
/* Clip nb_sectors relative to sector_num to not exceed end-of-file */
static inline int mirror_clip_sectors(MirrorBlockJob *s,
int64_t sector_num,
int nb_sectors)
{
return MIN(nb_sectors,
s->bdev_length / BDRV_SECTOR_SIZE - sector_num);
}
/* Round offset and/or bytes to target cluster if COW is needed, and
* return the offset of the adjusted tail against original. */
static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset,
@ -336,30 +327,28 @@ static void mirror_do_zero_or_discard(MirrorBlockJob *s,
static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
{
BlockDriverState *source = s->source;
int64_t sector_num, first_chunk;
int64_t offset, 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_bytes = MAX(s->buf_size / MAX_IN_FLIGHT, MAX_IO_BYTES);
bdrv_dirty_bitmap_lock(s->dirty_bitmap);
sector_num = bdrv_dirty_iter_next(s->dbi);
if (sector_num < 0) {
offset = bdrv_dirty_iter_next(s->dbi) * BDRV_SECTOR_SIZE;
if (offset < 0) {
bdrv_set_dirty_iter(s->dbi, 0);
sector_num = bdrv_dirty_iter_next(s->dbi);
offset = bdrv_dirty_iter_next(s->dbi) * BDRV_SECTOR_SIZE;
trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap) *
BDRV_SECTOR_SIZE);
assert(sector_num >= 0);
assert(offset >= 0);
}
bdrv_dirty_bitmap_unlock(s->dirty_bitmap);
first_chunk = sector_num / sectors_per_chunk;
first_chunk = offset / s->granularity;
while (test_bit(first_chunk, s->in_flight_bitmap)) {
trace_mirror_yield_in_flight(s, sector_num * BDRV_SECTOR_SIZE,
s->in_flight);
trace_mirror_yield_in_flight(s, offset, s->in_flight);
mirror_wait_for_io(s);
}
@ -368,25 +357,26 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
/* Find the number of consective dirty chunks following the first dirty
* one, and wait for in flight requests in them. */
bdrv_dirty_bitmap_lock(s->dirty_bitmap);
while (nb_chunks * sectors_per_chunk < (s->buf_size >> BDRV_SECTOR_BITS)) {
while (nb_chunks * s->granularity < s->buf_size) {
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_locked(source, s->dirty_bitmap, next_sector)) {
int64_t next_offset = offset + nb_chunks * s->granularity;
int64_t next_chunk = next_offset / s->granularity;
if (next_offset >= s->bdev_length ||
!bdrv_get_dirty_locked(source, s->dirty_bitmap,
next_offset >> BDRV_SECTOR_BITS)) {
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) {
next_dirty = bdrv_dirty_iter_next(s->dbi) * BDRV_SECTOR_SIZE;
if (next_dirty > next_offset || 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);
bdrv_set_dirty_iter(s->dbi, next_offset >> BDRV_SECTOR_BITS);
next_dirty = bdrv_dirty_iter_next(s->dbi) * BDRV_SECTOR_SIZE;
}
assert(next_dirty == next_sector);
assert(next_dirty == next_offset);
nb_chunks++;
}
@ -394,14 +384,15 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
* 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_locked(s->dirty_bitmap, sector_num,
nb_chunks * sectors_per_chunk);
bdrv_reset_dirty_bitmap_locked(s->dirty_bitmap, offset >> BDRV_SECTOR_BITS,
nb_chunks * sectors_per_chunk);
bdrv_dirty_bitmap_unlock(s->dirty_bitmap);
bitmap_set(s->in_flight_bitmap, sector_num / sectors_per_chunk, nb_chunks);
while (nb_chunks > 0 && sector_num < end) {
bitmap_set(s->in_flight_bitmap, offset / s->granularity, nb_chunks);
while (nb_chunks > 0 && offset < s->bdev_length) {
int64_t ret;
int io_sectors;
unsigned int io_bytes;
int64_t io_bytes_acct;
BlockDriverState *file;
enum MirrorMethod {
@ -410,28 +401,28 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
MIRROR_METHOD_DISCARD
} mirror_method = MIRROR_METHOD_COPY;
assert(!(sector_num % sectors_per_chunk));
ret = bdrv_get_block_status_above(source, NULL, sector_num,
assert(!(offset % s->granularity));
ret = bdrv_get_block_status_above(source, NULL,
offset >> BDRV_SECTOR_BITS,
nb_chunks * sectors_per_chunk,
&io_sectors, &file);
io_bytes = io_sectors * BDRV_SECTOR_SIZE;
if (ret < 0) {
io_sectors = MIN(nb_chunks * sectors_per_chunk,
max_io_bytes >> BDRV_SECTOR_BITS);
io_bytes = MIN(nb_chunks * s->granularity, max_io_bytes);
} else if (ret & BDRV_BLOCK_DATA) {
io_sectors = MIN(io_sectors, max_io_bytes >> BDRV_SECTOR_BITS);
io_bytes = MIN(io_bytes, max_io_bytes);
}
io_sectors -= io_sectors % sectors_per_chunk;
if (io_sectors < sectors_per_chunk) {
io_sectors = sectors_per_chunk;
io_bytes -= io_bytes % s->granularity;
if (io_bytes < s->granularity) {
io_bytes = s->granularity;
} 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) {
int64_t target_offset;
unsigned int target_bytes;
bdrv_round_to_clusters(blk_bs(s->target), offset, io_bytes,
&target_offset, &target_bytes);
if (target_offset == offset &&
target_bytes == io_bytes) {
mirror_method = ret & BDRV_BLOCK_ZERO ?
MIRROR_METHOD_ZERO :
MIRROR_METHOD_DISCARD;
@ -439,8 +430,7 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
}
while (s->in_flight >= MAX_IN_FLIGHT) {
trace_mirror_yield_in_flight(s, sector_num * BDRV_SECTOR_SIZE,
s->in_flight);
trace_mirror_yield_in_flight(s, offset, s->in_flight);
mirror_wait_for_io(s);
}
@ -448,30 +438,27 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
return 0;
}
io_sectors = mirror_clip_sectors(s, sector_num, io_sectors);
io_bytes = mirror_clip_bytes(s, offset, io_bytes);
switch (mirror_method) {
case MIRROR_METHOD_COPY:
io_bytes_acct = mirror_do_read(s, sector_num * BDRV_SECTOR_SIZE,
io_sectors * BDRV_SECTOR_SIZE);
io_sectors = io_bytes_acct / BDRV_SECTOR_SIZE;
io_bytes = io_bytes_acct = mirror_do_read(s, offset, io_bytes);
break;
case MIRROR_METHOD_ZERO:
case MIRROR_METHOD_DISCARD:
mirror_do_zero_or_discard(s, sector_num * BDRV_SECTOR_SIZE,
io_sectors * BDRV_SECTOR_SIZE,
mirror_do_zero_or_discard(s, offset, io_bytes,
mirror_method == MIRROR_METHOD_DISCARD);
if (write_zeroes_ok) {
io_bytes_acct = 0;
} else {
io_bytes_acct = io_sectors * BDRV_SECTOR_SIZE;
io_bytes_acct = io_bytes;
}
break;
default:
abort();
}
assert(io_sectors);
sector_num += io_sectors;
nb_chunks -= DIV_ROUND_UP(io_sectors, sectors_per_chunk);
assert(io_bytes);
offset += io_bytes;
nb_chunks -= DIV_ROUND_UP(io_bytes, s->granularity);
if (s->common.speed) {
delay_ns = ratelimit_calculate_delay(&s->limit, io_bytes_acct);
}