mirror: Switch MirrorBlockJob to byte-based
We are gradually converting to byte-based interfaces, as they are
easier to reason about than sector-based. Continue by converting an
internal structure (no semantic change), and all references to the
buffer size.
Add an assertion that our use of s->granularity >> BDRV_SECTOR_BITS
(necessary for interaction with sector-based dirty bitmaps, until
a later patch converts those to be byte-based) does not suffer from
truncation problems.
[checkpatch has a false positive on use of MIN() in this patch]
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block/mirror.c b/block/mirror.c
index b4dfe95..10f4e9b 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -24,9 +24,8 @@
#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)
+#define MAX_IO_BYTES (1 << 20) /* 1 Mb */
+#define DEFAULT_MIRROR_BUF_SIZE (MAX_IN_FLIGHT * MAX_IO_BYTES)
/* The mirroring buffer is a list of granularity-sized chunks.
* Free chunks are organized in a list.
@@ -67,11 +66,11 @@
uint64_t last_pause_ns;
unsigned long *in_flight_bitmap;
int in_flight;
- int64_t sectors_in_flight;
+ int64_t bytes_in_flight;
int ret;
bool unmap;
bool waiting_for_io;
- int target_cluster_sectors;
+ int target_cluster_size;
int max_iov;
bool initial_zeroing_ongoing;
} MirrorBlockJob;
@@ -79,8 +78,8 @@
typedef struct MirrorOp {
MirrorBlockJob *s;
QEMUIOVector qiov;
- int64_t sector_num;
- int nb_sectors;
+ int64_t offset;
+ uint64_t bytes;
} MirrorOp;
static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read,
@@ -101,13 +100,12 @@
MirrorBlockJob *s = op->s;
struct iovec *iov;
int64_t chunk_num;
- int i, nb_chunks, sectors_per_chunk;
+ int i, nb_chunks;
- trace_mirror_iteration_done(s, op->sector_num * BDRV_SECTOR_SIZE,
- op->nb_sectors * BDRV_SECTOR_SIZE, ret);
+ trace_mirror_iteration_done(s, op->offset, op->bytes, ret);
s->in_flight--;
- s->sectors_in_flight -= op->nb_sectors;
+ s->bytes_in_flight -= op->bytes;
iov = op->qiov.iov;
for (i = 0; i < op->qiov.niov; i++) {
MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base;
@@ -115,16 +113,15 @@
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);
+ chunk_num = op->offset / s->granularity;
+ nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity);
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;
+ s->common.offset += op->bytes;
}
}
qemu_iovec_destroy(&op->qiov);
@@ -144,7 +141,8 @@
if (ret < 0) {
BlockErrorAction action;
- bdrv_set_dirty_bitmap(s->dirty_bitmap, op->sector_num, op->nb_sectors);
+ bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset >> BDRV_SECTOR_BITS,
+ op->bytes >> BDRV_SECTOR_BITS);
action = mirror_error_action(s, false, -ret);
if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) {
s->ret = ret;
@@ -163,7 +161,8 @@
if (ret < 0) {
BlockErrorAction action;
- bdrv_set_dirty_bitmap(s->dirty_bitmap, op->sector_num, op->nb_sectors);
+ bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset >> BDRV_SECTOR_BITS,
+ op->bytes >> BDRV_SECTOR_BITS);
action = mirror_error_action(s, true, -ret);
if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) {
s->ret = ret;
@@ -171,7 +170,7 @@
mirror_iteration_done(op, ret);
} else {
- blk_aio_pwritev(s->target, op->sector_num * BDRV_SECTOR_SIZE, &op->qiov,
+ blk_aio_pwritev(s->target, op->offset, &op->qiov,
0, mirror_write_complete, op);
}
aio_context_release(blk_get_aio_context(s->common.blk));
@@ -211,7 +210,8 @@
align_nb_sectors = max_sectors;
if (need_cow) {
align_nb_sectors = QEMU_ALIGN_DOWN(align_nb_sectors,
- s->target_cluster_sectors);
+ s->target_cluster_size >>
+ BDRV_SECTOR_BITS);
}
}
/* Clipping may result in align_nb_sectors unaligned to chunk boundary, but
@@ -277,8 +277,8 @@
/* 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;
+ op->offset = sector_num * BDRV_SECTOR_SIZE;
+ op->bytes = nb_sectors * BDRV_SECTOR_SIZE;
/* Now make a QEMUIOVector taking enough granularity-sized chunks
* from s->buf_free.
@@ -295,7 +295,7 @@
/* Copy the dirty cluster. */
s->in_flight++;
- s->sectors_in_flight += nb_sectors;
+ s->bytes_in_flight += nb_sectors * BDRV_SECTOR_SIZE;
trace_mirror_one_iteration(s, sector_num * BDRV_SECTOR_SIZE,
nb_sectors * BDRV_SECTOR_SIZE);
@@ -315,19 +315,17 @@
* 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;
+ op->offset = sector_num * BDRV_SECTOR_SIZE;
+ op->bytes = nb_sectors * BDRV_SECTOR_SIZE;
s->in_flight++;
- s->sectors_in_flight += nb_sectors;
+ s->bytes_in_flight += nb_sectors * BDRV_SECTOR_SIZE;
if (is_discard) {
blk_aio_pdiscard(s->target, sector_num << BDRV_SECTOR_BITS,
- op->nb_sectors << BDRV_SECTOR_BITS,
- mirror_write_complete, op);
+ op->bytes, 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,
+ op->bytes, s->unmap ? BDRV_REQ_MAY_UNMAP : 0,
mirror_write_complete, op);
}
}
@@ -342,8 +340,7 @@
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);
+ 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);
@@ -415,9 +412,10 @@
nb_chunks * sectors_per_chunk,
&io_sectors, &file);
if (ret < 0) {
- io_sectors = MIN(nb_chunks * sectors_per_chunk, max_io_sectors);
+ io_sectors = MIN(nb_chunks * sectors_per_chunk,
+ max_io_bytes >> BDRV_SECTOR_BITS);
} else if (ret & BDRV_BLOCK_DATA) {
- io_sectors = MIN(io_sectors, max_io_sectors);
+ io_sectors = MIN(io_sectors, max_io_bytes >> BDRV_SECTOR_BITS);
}
io_sectors -= io_sectors % sectors_per_chunk;
@@ -719,7 +717,6 @@
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;
@@ -771,14 +768,15 @@
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;
+ s->target_cluster_size = bdi.cluster_size;
+ } else {
+ s->target_cluster_size = BDRV_SECTOR_SIZE;
}
- if (backing_filename[0] && !target_bs->backing
- && s->granularity < target_cluster_size) {
- s->buf_size = MAX(s->buf_size, target_cluster_size);
+ if (backing_filename[0] && !target_bs->backing &&
+ s->granularity < s->target_cluster_size) {
+ s->buf_size = MAX(s->buf_size, s->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);
@@ -814,10 +812,10 @@
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
+ * s->bytes_in_flight is the number of bytes 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;
+ s->common.len = s->common.offset + s->bytes_in_flight +
+ cnt * 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.
@@ -1150,6 +1148,8 @@
}
assert ((granularity & (granularity - 1)) == 0);
+ /* Granularity must be large enough for sector-based dirty bitmap */
+ assert(granularity >= BDRV_SECTOR_SIZE);
if (buf_size < 0) {
error_setg(errp, "Invalid parameter 'buf-size'");
