diff options
author | Eric Blake <eblake@redhat.com> | 2017-07-07 07:44:50 -0500 |
---|---|---|
committer | Kevin Wolf <kwolf@redhat.com> | 2017-07-10 13:18:06 +0200 |
commit | ae4cc8777b456ab87ca1f02b98b006ec0c96335e (patch) | |
tree | 9fb39918b1608b4bf91071a149340c711911f0d8 /block/mirror.c | |
parent | 782d97efec66d743f87f28f1d040cdfacc380b1e (diff) |
mirror: Switch mirror_do_read() to byte-based
We are gradually converting to byte-based interfaces, as they are
easier to reason about than sector-based. Convert another internal
function, preserving all existing semantics, and adding one more
assertion that things are still sector-aligned (so that conversions
to sectors in mirror_read_complete don't need to round).
Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block/mirror.c')
-rw-r--r-- | block/mirror.c | 74 |
1 files changed, 33 insertions, 41 deletions
diff --git a/block/mirror.c b/block/mirror.c index 0378bd2977..262fddf2ce 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -196,7 +196,7 @@ static inline int mirror_clip_sectors(MirrorBlockJob *s, /* 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, - unsigned int *bytes) + uint64_t *bytes) { bool need_cow; int ret = 0; @@ -204,6 +204,7 @@ static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset, unsigned int align_bytes = *bytes; int max_bytes = s->granularity * s->max_iov; + assert(*bytes < INT_MAX); need_cow = !test_bit(*offset / s->granularity, s->cow_bitmap); need_cow |= !test_bit((*offset + *bytes - 1) / s->granularity, s->cow_bitmap); @@ -238,59 +239,51 @@ static inline void mirror_wait_for_io(MirrorBlockJob *s) } /* 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 + * Returns: The number of bytes copied after and including offset, + * excluding any bytes copied prior to offset due to alignment. + * This will be @bytes if no alignment is necessary, or + * (new_end - offset) 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) +static uint64_t mirror_do_read(MirrorBlockJob *s, int64_t offset, + uint64_t bytes) { BlockBackend *source = s->common.blk; - int sectors_per_chunk, nb_chunks; - int ret; + int nb_chunks; + uint64_t ret; MirrorOp *op; - int max_sectors; + uint64_t max_bytes; - sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; - max_sectors = sectors_per_chunk * s->max_iov; + max_bytes = s->granularity * 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); - assert(nb_sectors < BDRV_REQUEST_MAX_SECTORS); - ret = nb_sectors; + bytes = MIN(s->buf_size, MIN(max_bytes, bytes)); + assert(bytes); + assert(bytes < BDRV_REQUEST_MAX_BYTES); + ret = bytes; if (s->cow_bitmap) { - int64_t offset = sector_num * BDRV_SECTOR_SIZE; - unsigned int bytes = nb_sectors * BDRV_SECTOR_SIZE; - int gap; - - gap = mirror_cow_align(s, &offset, &bytes); - sector_num = offset / BDRV_SECTOR_SIZE; - nb_sectors = bytes / BDRV_SECTOR_SIZE; - ret += gap / BDRV_SECTOR_SIZE; + ret += mirror_cow_align(s, &offset, &bytes); } - assert(nb_sectors << BDRV_SECTOR_BITS <= s->buf_size); - /* The sector range must meet granularity because: + assert(bytes <= s->buf_size); + /* The offset is granularity-aligned 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); + assert(QEMU_IS_ALIGNED(offset, s->granularity)); + /* The range is sector-aligned, since bdrv_getlength() rounds up. */ + assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE)); + nb_chunks = DIV_ROUND_UP(bytes, s->granularity); while (s->buf_free_count < nb_chunks) { - 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); } /* Allocate a MirrorOp that is used as an AIO callback. */ op = g_new(MirrorOp, 1); op->s = s; - op->offset = sector_num * BDRV_SECTOR_SIZE; - op->bytes = nb_sectors * BDRV_SECTOR_SIZE; + op->offset = offset; + op->bytes = bytes; /* Now make a QEMUIOVector taking enough granularity-sized chunks * from s->buf_free. @@ -298,7 +291,7 @@ static int mirror_do_read(MirrorBlockJob *s, int64_t sector_num, 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; + size_t remaining = bytes - op->qiov.size; QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next); s->buf_free_count--; @@ -307,12 +300,10 @@ static int mirror_do_read(MirrorBlockJob *s, int64_t sector_num, /* Copy the dirty cluster. */ s->in_flight++; - s->bytes_in_flight += nb_sectors * BDRV_SECTOR_SIZE; - trace_mirror_one_iteration(s, sector_num * BDRV_SECTOR_SIZE, - nb_sectors * BDRV_SECTOR_SIZE); + s->bytes_in_flight += bytes; + trace_mirror_one_iteration(s, offset, bytes); - blk_aio_preadv(source, sector_num * BDRV_SECTOR_SIZE, &op->qiov, 0, - mirror_read_complete, op); + blk_aio_preadv(source, offset, &op->qiov, 0, mirror_read_complete, op); return ret; } @@ -460,8 +451,9 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) io_sectors = 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_bytes_acct = io_sectors * BDRV_SECTOR_SIZE; + 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; break; case MIRROR_METHOD_ZERO: case MIRROR_METHOD_DISCARD: |