From cf081fca4e3cc02a309659b571ab0c5b225ea4cf Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Wed, 1 Jun 2016 15:10:02 -0600 Subject: [PATCH] block: Track write zero limits in bytes Another step towards removing sector-based interfaces: convert the maximum write and minimum alignment values from sectors to bytes. Rename the variables to let the compiler check that all users are converted to the new semantics. The maximum remains an int as long as BDRV_REQUEST_MAX_SECTORS is constrained by INT_MAX (this means that we can't even support a 2G write_zeroes, but just under it) - changing operation lengths to unsigned or to 64-bits is a much bigger audit, and debatable if we even want to do it (since at the core, a 32-bit platform will still have ssize_t as its underlying limit on write()). Meanwhile, alignment is changed to 'uint32_t', since it makes no sense to have an alignment larger than the maximum write, and less painful to use an unsigned type with well-defined behavior in bit operations than to have to worry about what happens if a driver mistakenly supplies a negative alignment. Add an assert that no one was trying to use sectors to get a write zeroes larger than 2G, and therefore that a later conversion to bytes won't be impacted by keeping the limit at 32 bits. Signed-off-by: Eric Blake Signed-off-by: Kevin Wolf --- block/io.c | 22 +++++++++++++--------- block/iscsi.c | 13 ++++++------- block/qcow2.c | 2 +- block/qed.c | 2 +- block/vmdk.c | 6 +++--- include/block/block_int.h | 10 ++++++---- 6 files changed, 30 insertions(+), 25 deletions(-) diff --git a/block/io.c b/block/io.c index c73be55f86..1eda1b2f58 100644 --- a/block/io.c +++ b/block/io.c @@ -1121,15 +1121,19 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs, int head = 0; int tail = 0; - int max_write_zeroes = MIN_NON_ZERO(bs->bl.max_write_zeroes, - BDRV_REQUEST_MAX_SECTORS); - if (bs->bl.write_zeroes_alignment) { - assert(is_power_of_2(bs->bl.write_zeroes_alignment)); - head = sector_num & (bs->bl.write_zeroes_alignment - 1); - tail = (sector_num + nb_sectors) & (bs->bl.write_zeroes_alignment - 1); - max_write_zeroes &= ~(bs->bl.write_zeroes_alignment - 1); + int max_write_zeroes = MIN_NON_ZERO(bs->bl.max_pwrite_zeroes, INT_MAX); + int write_zeroes_sector_align = + bs->bl.pwrite_zeroes_alignment >> BDRV_SECTOR_BITS; + + max_write_zeroes >>= BDRV_SECTOR_BITS; + if (write_zeroes_sector_align) { + assert(is_power_of_2(bs->bl.pwrite_zeroes_alignment)); + head = sector_num & (write_zeroes_sector_align - 1); + tail = (sector_num + nb_sectors) & (write_zeroes_sector_align - 1); + max_write_zeroes &= ~(write_zeroes_sector_align - 1); } + assert(nb_sectors <= BDRV_REQUEST_MAX_SECTORS); while (nb_sectors > 0 && !ret) { int num = nb_sectors; @@ -1139,9 +1143,9 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs, */ if (head) { /* Make a small request up to the first aligned sector. */ - num = MIN(nb_sectors, bs->bl.write_zeroes_alignment - head); + num = MIN(nb_sectors, write_zeroes_sector_align - head); head = 0; - } else if (tail && num > bs->bl.write_zeroes_alignment) { + } else if (tail && num > write_zeroes_sector_align) { /* Shorten the request to the last aligned sector. */ num -= tail; } diff --git a/block/iscsi.c b/block/iscsi.c index 94f9974f10..52ea9d7a70 100644 --- a/block/iscsi.c +++ b/block/iscsi.c @@ -1715,16 +1715,15 @@ static void iscsi_refresh_limits(BlockDriverState *bs, Error **errp) bs->bl.discard_alignment = iscsilun->block_size >> BDRV_SECTOR_BITS; } - if (iscsilun->bl.max_ws_len < 0xffffffff) { - bs->bl.max_write_zeroes = - sector_limits_lun2qemu(iscsilun->bl.max_ws_len, iscsilun); + if (iscsilun->bl.max_ws_len < 0xffffffff / iscsilun->block_size) { + bs->bl.max_pwrite_zeroes = + iscsilun->bl.max_ws_len * iscsilun->block_size; } if (iscsilun->lbp.lbpws) { - bs->bl.write_zeroes_alignment = - sector_limits_lun2qemu(iscsilun->bl.opt_unmap_gran, iscsilun); + bs->bl.pwrite_zeroes_alignment = + iscsilun->bl.opt_unmap_gran * iscsilun->block_size; } else { - bs->bl.write_zeroes_alignment = - iscsilun->block_size >> BDRV_SECTOR_BITS; + bs->bl.pwrite_zeroes_alignment = iscsilun->block_size; } bs->bl.opt_transfer_length = sector_limits_lun2qemu(iscsilun->bl.opt_xfer_len, iscsilun); diff --git a/block/qcow2.c b/block/qcow2.c index ecac399b43..a6ea6cb62d 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1193,7 +1193,7 @@ static void qcow2_refresh_limits(BlockDriverState *bs, Error **errp) { BDRVQcow2State *s = bs->opaque; - bs->bl.write_zeroes_alignment = s->cluster_sectors; + bs->bl.pwrite_zeroes_alignment = s->cluster_size; } static int qcow2_set_key(BlockDriverState *bs, const char *key) diff --git a/block/qed.c b/block/qed.c index 0f621924f8..113b8e8cc6 100644 --- a/block/qed.c +++ b/block/qed.c @@ -517,7 +517,7 @@ static void bdrv_qed_refresh_limits(BlockDriverState *bs, Error **errp) { BDRVQEDState *s = bs->opaque; - bs->bl.write_zeroes_alignment = s->header.cluster_size >> BDRV_SECTOR_BITS; + bs->bl.pwrite_zeroes_alignment = s->header.cluster_size; } /* We have nothing to do for QED reopen, stubs just return diff --git a/block/vmdk.c b/block/vmdk.c index 2205cc888f..5a01e1672f 100644 --- a/block/vmdk.c +++ b/block/vmdk.c @@ -997,9 +997,9 @@ static void vmdk_refresh_limits(BlockDriverState *bs, Error **errp) for (i = 0; i < s->num_extents; i++) { if (!s->extents[i].flat) { - bs->bl.write_zeroes_alignment = - MAX(bs->bl.write_zeroes_alignment, - s->extents[i].cluster_sectors); + bs->bl.pwrite_zeroes_alignment = + MAX(bs->bl.pwrite_zeroes_alignment, + s->extents[i].cluster_sectors << BDRV_SECTOR_BITS); } } } diff --git a/include/block/block_int.h b/include/block/block_int.h index 30a97178c8..2e9c81ff95 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -328,11 +328,13 @@ typedef struct BlockLimits { /* optimal alignment for discard requests in sectors */ int64_t discard_alignment; - /* maximum number of sectors that can zeroized at once */ - int max_write_zeroes; + /* maximum number of bytes that can zeroized at once (since it is + * signed, it must be < 2G, if set) */ + int32_t max_pwrite_zeroes; - /* optimal alignment for write zeroes requests in sectors */ - int64_t write_zeroes_alignment; + /* optimal alignment for write zeroes requests in bytes, must be + * power of 2, and less than max_pwrite_zeroes if that is set */ + uint32_t pwrite_zeroes_alignment; /* optimal transfer length in sectors */ int opt_transfer_length; -- GitLab