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[PATCH 3/5] block: add max_pwrite_zeroes_no_fallback to BlockLimits
From: |
Vladimir Sementsov-Ogievskiy |
Subject: |
[PATCH 3/5] block: add max_pwrite_zeroes_no_fallback to BlockLimits |
Date: |
Mon, 2 Mar 2020 13:05:35 +0300 |
NBD spec is updated, so that max_block doesn't relate to
NBD_CMD_WRITE_ZEROES with NBD_CMD_FLAG_FAST_ZERO (which mirrors Qemu
flag BDRV_REQ_NO_FALLBACK). To drop the restriction we need new
max_pwrite_zeroes_no_fallback.
Default value of new max_pwrite_zeroes_no_fallback is zero and it means
no-restriction, so we are automatically done by this commit. Note that
nbd and blkdebug are the only drivers which in the same time define
max_pwrite_zeroes limit and support BDRV_REQ_NO_FALLBACK, so we need to
update only blkdebug.
Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
include/block/block_int.h | 8 ++++++++
block/blkdebug.c | 7 ++++++-
block/io.c | 4 +++-
3 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 6f9fd5e20e..c167e887c6 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -618,6 +618,14 @@ typedef struct BlockLimits {
* pwrite_zeroes_alignment. May be 0 if no inherent 32-bit limit */
int32_t max_pwrite_zeroes;
+ /*
+ * Maximum number of bytes that can zeroized at once if flag
+ * BDRV_REQ_NO_FALLBACK specified (since it is signed, it must be < 2G, if
+ * set). Must be multiple of pwrite_zeroes_alignment. May be 0 if no
+ * inherent 32-bit limit.
+ */
+ int32_t max_pwrite_zeroes_no_fallback;
+
/* Optimal alignment for write zeroes requests in bytes. A power
* of 2 is best but not mandatory. Must be a multiple of
* bl.request_alignment, and must be less than max_pwrite_zeroes
diff --git a/block/blkdebug.c b/block/blkdebug.c
index af44aa973f..7627fbcb3b 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -692,7 +692,11 @@ static int coroutine_fn
blkdebug_co_pwrite_zeroes(BlockDriverState *bs,
}
assert(QEMU_IS_ALIGNED(offset, align));
assert(QEMU_IS_ALIGNED(bytes, align));
- if (bs->bl.max_pwrite_zeroes) {
+ if ((flags & BDRV_REQ_NO_FALLBACK) &&
+ bs->bl.max_pwrite_zeroes_no_fallback)
+ {
+ assert(bytes <= bs->bl.max_pwrite_zeroes_no_fallback);
+ } else if (bs->bl.max_pwrite_zeroes) {
assert(bytes <= bs->bl.max_pwrite_zeroes);
}
@@ -977,6 +981,7 @@ static void blkdebug_refresh_limits(BlockDriverState *bs,
Error **errp)
}
if (s->max_write_zero) {
bs->bl.max_pwrite_zeroes = s->max_write_zero;
+ bs->bl.max_pwrite_zeroes_no_fallback = s->max_write_zero;
}
if (s->opt_discard) {
bs->bl.pdiscard_alignment = s->opt_discard;
diff --git a/block/io.c b/block/io.c
index 7e4cb74cf4..75fd5600c2 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1752,7 +1752,9 @@ static int coroutine_fn
bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
int head = 0;
int tail = 0;
- int max_write_zeroes = MIN_NON_ZERO(bs->bl.max_pwrite_zeroes, INT_MAX);
+ int max_write_zeroes = MIN_NON_ZERO((flags & BDRV_REQ_NO_FALLBACK) ?
+ bs->bl.max_pwrite_zeroes_no_fallback :
+ bs->bl.max_pwrite_zeroes, INT_MAX);
int alignment = MAX(bs->bl.pwrite_zeroes_alignment,
bs->bl.request_alignment);
int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, MAX_BOUNCE_BUFFER);
--
2.21.0