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Re: [Qemu-block] [PATCH 17/17] block: Make bdrv_is_allocated_above() byt
From: |
John Snow |
Subject: |
Re: [Qemu-block] [PATCH 17/17] block: Make bdrv_is_allocated_above() byte-based |
Date: |
Mon, 24 Apr 2017 19:06:43 -0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.0 |
On 04/11/2017 06:29 PM, Eric Blake wrote:
> We are gradually moving away from sector-based interfaces, towards
> byte-based. In the common case, allocation is unlikely to ever use
> values that are not naturally sector-aligned, but it is possible
> that byte-based values will let us be more precise about allocation
> at the end of an unaligned file that can do byte-based access.
>
> Changing the signature of the function to use int64_t *pnum ensures
> that the compiler enforces that all callers are updated. For now,
> the io.c layer still assert()s that all callers are sector-aligned,
> but that can be relaxed when a later patch implements byte-based
> block status. Therefore, for the most part this patch is just the
> addition of scaling at the callers followed by inverse scaling at
> bdrv_is_allocated(). But some code, particularly stream_run(),
> gets a lot simpler because it no longer has to mess with sectors.
>
> For ease of review, bdrv_is_allocated() was tackled separately.
>
> Signed-off-by: Eric Blake <address@hidden>
> ---
> include/block/block.h | 2 +-
> block/commit.c | 20 ++++++++------------
> block/io.c | 36 +++++++++++++++---------------------
> block/mirror.c | 5 ++++-
> block/replication.c | 17 ++++++++++++-----
> block/stream.c | 21 +++++++++------------
> qemu-img.c | 10 +++++++---
> 7 files changed, 56 insertions(+), 55 deletions(-)
>
> diff --git a/include/block/block.h b/include/block/block.h
> index 8641149..740cb86 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -425,7 +425,7 @@ int64_t bdrv_get_block_status_above(BlockDriverState *bs,
> int bdrv_is_allocated(BlockDriverState *bs, int64_t offset, int64_t bytes,
> int64_t *pnum);
> int bdrv_is_allocated_above(BlockDriverState *top, BlockDriverState *base,
> - int64_t sector_num, int nb_sectors, int *pnum);
> + int64_t offset, int64_t bytes, int64_t *pnum);
>
> bool bdrv_is_read_only(BlockDriverState *bs);
> bool bdrv_is_sg(BlockDriverState *bs);
> diff --git a/block/commit.c b/block/commit.c
> index 4d6bb2a..989de7d 100644
> --- a/block/commit.c
> +++ b/block/commit.c
> @@ -132,7 +132,7 @@ static void coroutine_fn commit_run(void *opaque)
> int64_t offset;
> uint64_t delay_ns = 0;
> int ret = 0;
> - int n = 0; /* sectors */
> + int64_t n = 0; /* bytes */
> void *buf = NULL;
> int bytes_written = 0;
> int64_t base_len;
> @@ -157,7 +157,7 @@ static void coroutine_fn commit_run(void *opaque)
>
> buf = blk_blockalign(s->top, COMMIT_BUFFER_SIZE);
>
> - for (offset = 0; offset < s->common.len; offset += n * BDRV_SECTOR_SIZE)
> {
> + for (offset = 0; offset < s->common.len; offset += n) {
> bool copy;
>
> /* Note that even when no rate limit is applied we need to yield
> @@ -169,15 +169,12 @@ static void coroutine_fn commit_run(void *opaque)
> }
> /* Copy if allocated above the base */
> ret = bdrv_is_allocated_above(blk_bs(s->top), blk_bs(s->base),
> - offset / BDRV_SECTOR_SIZE,
> - COMMIT_BUFFER_SIZE / BDRV_SECTOR_SIZE,
> - &n);
> + offset, COMMIT_BUFFER_SIZE, &n);
> copy = (ret == 1);
> - trace_commit_one_iteration(s, offset, n * BDRV_SECTOR_SIZE, ret);
> + trace_commit_one_iteration(s, offset, n, ret);
> if (copy) {
> - ret = commit_populate(s->top, s->base, offset,
> - n * BDRV_SECTOR_SIZE, buf);
> - bytes_written += n * BDRV_SECTOR_SIZE;
> + ret = commit_populate(s->top, s->base, offset, n, buf);
> + bytes_written += n;
> }
> if (ret < 0) {
> BlockErrorAction action =
> @@ -190,11 +187,10 @@ static void coroutine_fn commit_run(void *opaque)
> }
> }
> /* Publish progress */
> - s->common.offset += n * BDRV_SECTOR_SIZE;
> + s->common.offset += n;
>
> if (copy && s->common.speed) {
> - delay_ns = ratelimit_calculate_delay(&s->limit,
> - n * BDRV_SECTOR_SIZE);
> + delay_ns = ratelimit_calculate_delay(&s->limit, n);
> }
> }
>
> diff --git a/block/io.c b/block/io.c
> index 438a493..9218329 100644
> --- a/block/io.c
> +++ b/block/io.c
> @@ -1930,52 +1930,46 @@ int coroutine_fn bdrv_is_allocated(BlockDriverState
> *bs, int64_t offset,
> /*
> * Given an image chain: ... -> [BASE] -> [INTER1] -> [INTER2] -> [TOP]
> *
> - * Return true if the given sector is allocated in any image between
> + * Return true if the given offset is allocated in any image between
perhaps "range" instead of "offset"?
> * BASE and TOP (inclusive). BASE can be NULL to check if the given
> - * sector is allocated in any image of the chain. Return false otherwise,
> + * offset is allocated in any image of the chain. Return false otherwise,
> * or negative errno on failure.
> *
> - * 'pnum' is set to the number of sectors (including and immediately
> following
> - * the specified sector) that are known to be in the same
> + * 'pnum' is set to the number of bytes (including and immediately following
> + * the specified offset) that are known to be in the same
> * allocated/unallocated state.
> *
> */
> int bdrv_is_allocated_above(BlockDriverState *top,
> BlockDriverState *base,
> - int64_t sector_num,
> - int nb_sectors, int *pnum)
> + int64_t offset, int64_t bytes, int64_t *pnum)
> {
> BlockDriverState *intermediate;
> - int ret, n = nb_sectors;
> + int ret;
> + int64_t n = bytes;
>
> intermediate = top;
> while (intermediate && intermediate != base) {
> int64_t pnum_inter;
> - int psectors_inter;
>
> - ret = bdrv_is_allocated(intermediate, sector_num * BDRV_SECTOR_SIZE,
> - nb_sectors * BDRV_SECTOR_SIZE,
> - &pnum_inter);
> + ret = bdrv_is_allocated(intermediate, offset, bytes, &pnum_inter);
> if (ret < 0) {
> return ret;
> }
> - assert(pnum_inter < INT_MAX * BDRV_SECTOR_SIZE);
> - psectors_inter = pnum_inter >> BDRV_SECTOR_BITS;
> if (ret) {
> - *pnum = psectors_inter;
> + *pnum = pnum_inter;
> return 1;
> }
>
> /*
> - * [sector_num, nb_sectors] is unallocated on top but intermediate
> - * might have
> - *
> - * [sector_num+x, nr_sectors] allocated.
> + * [offset, bytes] is unallocated on top but intermediate
> + * might have [offset+x, bytes-x] allocated.
> */
> - if (n > psectors_inter &&
> + if (n > pnum_inter &&
> (intermediate == top ||
> - sector_num + psectors_inter < intermediate->total_sectors)) {
> - n = psectors_inter;
> + offset + pnum_inter < (intermediate->total_sectors *
> + BDRV_SECTOR_SIZE))) {
Naive question: not worth using either bdrv_getlength for bytes, or the
bdrv_nb_sectors helpers?
(Not sure if this is appropriate due to the variable length calls which
might disqualify it from internal usage)
> + n = pnum_inter;
> }
>
> intermediate = backing_bs(intermediate);
> diff --git a/block/mirror.c b/block/mirror.c
> index 8de0492..c92335a 100644
> --- a/block/mirror.c
> +++ b/block/mirror.c
> @@ -609,6 +609,7 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob
> *s)
> BlockDriverState *bs = s->source;
> BlockDriverState *target_bs = blk_bs(s->target);
> int ret, n;
> + int64_t count;
>
> end = s->bdev_length / BDRV_SECTOR_SIZE;
>
> @@ -658,11 +659,13 @@ static int coroutine_fn
> mirror_dirty_init(MirrorBlockJob *s)
> return 0;
> }
>
> - ret = bdrv_is_allocated_above(bs, base, sector_num, nb_sectors, &n);
> + ret = bdrv_is_allocated_above(bs, base, sector_num *
> BDRV_SECTOR_SIZE,
> + nb_sectors * BDRV_SECTOR_SIZE, &count);
> if (ret < 0) {
> return ret;
> }
>
> + n = DIV_ROUND_UP(count, BDRV_SECTOR_SIZE);
> assert(n > 0);
> if (ret == 1) {
> bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n);
> diff --git a/block/replication.c b/block/replication.c
> index 414ecc4..605d90f 100644
> --- a/block/replication.c
> +++ b/block/replication.c
> @@ -264,7 +264,8 @@ static coroutine_fn int
> replication_co_writev(BlockDriverState *bs,
> BdrvChild *top = bs->file;
> BdrvChild *base = s->secondary_disk;
> BdrvChild *target;
> - int ret, n;
> + int ret;
> + int64_t n;
>
> ret = replication_get_io_status(s);
> if (ret < 0) {
> @@ -283,14 +284,20 @@ static coroutine_fn int
> replication_co_writev(BlockDriverState *bs,
> */
> qemu_iovec_init(&hd_qiov, qiov->niov);
> while (remaining_sectors > 0) {
> - ret = bdrv_is_allocated_above(top->bs, base->bs, sector_num,
> - remaining_sectors, &n);
> + int64_t count;
> +
> + ret = bdrv_is_allocated_above(top->bs, base->bs,
> + sector_num * BDRV_SECTOR_SIZE,
> + remaining_sectors * BDRV_SECTOR_SIZE,
> + &count);
> if (ret < 0) {
> goto out1;
> }
>
> + assert(QEMU_IS_ALIGNED(count, BDRV_SECTOR_SIZE));
> + n = count >> BDRV_SECTOR_BITS;
> qemu_iovec_reset(&hd_qiov);
> - qemu_iovec_concat(&hd_qiov, qiov, bytes_done, n * BDRV_SECTOR_SIZE);
> + qemu_iovec_concat(&hd_qiov, qiov, bytes_done, count);
>
> target = ret ? top : base;
> ret = bdrv_co_writev(target, sector_num, n, &hd_qiov);
> @@ -300,7 +307,7 @@ static coroutine_fn int
> replication_co_writev(BlockDriverState *bs,
>
> remaining_sectors -= n;
> sector_num += n;
> - bytes_done += n * BDRV_SECTOR_SIZE;
> + bytes_done += count;
> }
>
> out1:
> diff --git a/block/stream.c b/block/stream.c
> index 85502eb..9033655 100644
> --- a/block/stream.c
> +++ b/block/stream.c
> @@ -112,7 +112,7 @@ static void coroutine_fn stream_run(void *opaque)
> uint64_t delay_ns = 0;
> int error = 0;
> int ret = 0;
> - int n = 0; /* sectors */
> + int64_t n = 0; /* bytes */
> void *buf;
>
> if (!bs->backing) {
> @@ -136,9 +136,8 @@ static void coroutine_fn stream_run(void *opaque)
> bdrv_enable_copy_on_read(bs);
> }
>
> - for ( ; offset < s->common.len; offset += n * BDRV_SECTOR_SIZE) {
> + for ( ; offset < s->common.len; offset += n) {
> bool copy;
> - int64_t count = 0;
>
> /* Note that even when no rate limit is applied we need to yield
> * with no pending I/O here so that bdrv_drain_all() returns.
> @@ -150,26 +149,25 @@ static void coroutine_fn stream_run(void *opaque)
>
> copy = false;
>
> - ret = bdrv_is_allocated(bs, offset, STREAM_BUFFER_SIZE, &count);
> - n = DIV_ROUND_UP(count, BDRV_SECTOR_SIZE);
> + ret = bdrv_is_allocated(bs, offset, STREAM_BUFFER_SIZE, &n);
> if (ret == 1) {
> /* Allocated in the top, no need to copy. */
> } else if (ret >= 0) {
> /* Copy if allocated in the intermediate images. Limit to the
> * known-unallocated area [offset, offset+n*BDRV_SECTOR_SIZE).
> */
> ret = bdrv_is_allocated_above(backing_bs(bs), base,
> - offset / BDRV_SECTOR_SIZE, n, &n);
> + offset, n, &n);
>
> /* Finish early if end of backing file has been reached */
> if (ret == 0 && n == 0) {
> - n = (s->common.len - offset) / BDRV_SECTOR_SIZE;
> + n = s->common.len - offset;
> }
>
> copy = (ret == 1);
> }
> - trace_stream_one_iteration(s, offset, n * BDRV_SECTOR_SIZE, ret);
> + trace_stream_one_iteration(s, offset, n, ret);
> if (copy) {
> - ret = stream_populate(blk, offset, n * BDRV_SECTOR_SIZE, buf);
> + ret = stream_populate(blk, offset, n, buf);
> }
> if (ret < 0) {
> BlockErrorAction action =
> @@ -188,10 +186,9 @@ static void coroutine_fn stream_run(void *opaque)
> ret = 0;
>
> /* Publish progress */
> - s->common.offset += n * BDRV_SECTOR_SIZE;
> + s->common.offset += n;
> if (copy && s->common.speed) {
> - delay_ns = ratelimit_calculate_delay(&s->limit,
> - n * BDRV_SECTOR_SIZE);
> + delay_ns = ratelimit_calculate_delay(&s->limit, n);
> }
> }
>
> diff --git a/qemu-img.c b/qemu-img.c
> index 2f21d69..d96b4d6 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -1448,12 +1448,16 @@ static int img_compare(int argc, char **argv)
> }
>
> for (;;) {
> + int64_t count;
> +
> nb_sectors = sectors_to_process(total_sectors_over, sector_num);
> if (nb_sectors <= 0) {
> break;
> }
> - ret = bdrv_is_allocated_above(blk_bs(blk_over), NULL, sector_num,
> - nb_sectors, &pnum);
> + ret = bdrv_is_allocated_above(blk_bs(blk_over), NULL,
> + sector_num * BDRV_SECTOR_SIZE,
> + nb_sectors * BDRV_SECTOR_SIZE,
> + &count);
> if (ret < 0) {
> ret = 3;
> error_report("Sector allocation test failed for %s",
> @@ -1461,7 +1465,7 @@ static int img_compare(int argc, char **argv)
> goto out;
>
> }
> - nb_sectors = pnum;
> + nb_sectors = DIV_ROUND_UP(count, BDRV_SECTOR_SIZE);
> if (ret) {
> ret = check_empty_sectors(blk_over, sector_num, nb_sectors,
> filename_over, buf1, quiet);
>
Reviewed-by: John Snow <address@hidden>
- [Qemu-block] [PATCH 14/17] backup: Switch backup_do_cow() to byte-based, (continued)
[Qemu-block] [PATCH 17/17] block: Make bdrv_is_allocated_above() byte-based, Eric Blake, 2017/04/11
- Re: [Qemu-block] [PATCH 17/17] block: Make bdrv_is_allocated_above() byte-based,
John Snow <=
Re: [Qemu-block] [PATCH 00/17] make bdrv_is_allocated[_above] byte-based, John Snow, 2017/04/17