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[Qemu-devel] [PATCH v4 03/15] block: introduce BDRV_REQ_ALLOCATE flag
From: |
Anton Nefedov |
Subject: |
[Qemu-devel] [PATCH v4 03/15] block: introduce BDRV_REQ_ALLOCATE flag |
Date: |
Tue, 1 Aug 2017 17:19:00 +0300 |
The flag is supposed to indicate that the region of the disk image has
to be sufficiently allocated so it reads as zeroes. The call with the flag
set has to return -ENOTSUP if allocation cannot be done efficiently
(i.e. without falling back to writing actual buffers)
Signed-off-by: Anton Nefedov <address@hidden>
---
include/block/block.h | 6 +++++-
include/block/block_int.h | 2 +-
block/io.c | 20 +++++++++++++++++---
3 files changed, 23 insertions(+), 5 deletions(-)
diff --git a/include/block/block.h b/include/block/block.h
index 7fe0125..828da67 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -65,9 +65,13 @@ typedef enum {
BDRV_REQ_NO_SERIALISING = 0x8,
BDRV_REQ_FUA = 0x10,
BDRV_REQ_WRITE_COMPRESSED = 0x20,
+ /* The BDRV_REQ_ALLOCATE flag is used to indicate that the driver has to
+ * efficiently allocate the space so it reads as zeroes, or return an
error.
+ */
+ BDRV_REQ_ALLOCATE = 0x40,
/* Mask of valid flags */
- BDRV_REQ_MASK = 0x3f,
+ BDRV_REQ_MASK = 0x7f,
} BdrvRequestFlags;
typedef struct BlockSizes {
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 9b94b32..9b64411 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -585,7 +585,7 @@ struct BlockDriverState {
/* Flags honored during pwrite (so far: BDRV_REQ_FUA) */
unsigned int supported_write_flags;
/* Flags honored during pwrite_zeroes (so far: BDRV_REQ_FUA,
- * BDRV_REQ_MAY_UNMAP) */
+ * BDRV_REQ_MAY_UNMAP, BDRV_REQ_ALLOCATE) */
unsigned int supported_zero_flags;
/* the following member gives a name to every node on the bs graph. */
diff --git a/block/io.c b/block/io.c
index 375fc66..04d495e 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1245,7 +1245,7 @@ static int coroutine_fn
bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
assert(!bs->supported_zero_flags);
}
- if (ret == -ENOTSUP) {
+ if (ret == -ENOTSUP && !(flags & BDRV_REQ_ALLOCATE)) {
/* Fall back to bounce buffer if write zeroes is unsupported */
BdrvRequestFlags write_flags = flags & ~BDRV_REQ_ZERO_WRITE;
@@ -1331,8 +1331,8 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild
*child,
ret = notifier_with_return_list_notify(&bs->before_write_notifiers, req);
if (!ret && bs->detect_zeroes != BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF &&
- !(flags & BDRV_REQ_ZERO_WRITE) && drv->bdrv_co_pwrite_zeroes &&
- qemu_iovec_is_zero(qiov)) {
+ !(flags & BDRV_REQ_ZERO_WRITE) && !(flags & BDRV_REQ_ALLOCATE) &&
+ drv->bdrv_co_pwrite_zeroes && qemu_iovec_is_zero(qiov)) {
flags |= BDRV_REQ_ZERO_WRITE;
if (bs->detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP) {
flags |= BDRV_REQ_MAY_UNMAP;
@@ -1410,6 +1410,9 @@ static int coroutine_fn bdrv_co_do_zero_pwritev(BdrvChild
*child,
assert(flags & BDRV_REQ_ZERO_WRITE);
if (head_padding_bytes || tail_padding_bytes) {
+ if (flags & BDRV_REQ_ALLOCATE) {
+ return -ENOTSUP;
+ }
buf = qemu_blockalign(bs, align);
iov = (struct iovec) {
.iov_base = buf,
@@ -1508,6 +1511,9 @@ int coroutine_fn bdrv_co_pwritev(BdrvChild *child,
return ret;
}
+ /* allocation request with qiov provided doesn't make much sense */
+ assert(!(qiov && flags & BDRV_REQ_ALLOCATE));
+
bdrv_inc_in_flight(bs);
/*
* Align write if necessary by performing a read-modify-write cycle.
@@ -1639,6 +1645,14 @@ int coroutine_fn bdrv_co_pwrite_zeroes(BdrvChild *child,
int64_t offset,
{
trace_bdrv_co_pwrite_zeroes(child->bs, offset, bytes, flags);
+ assert(!(flags & BDRV_REQ_MAY_UNMAP && flags & BDRV_REQ_ALLOCATE));
+
+ if (flags & BDRV_REQ_ALLOCATE &&
+ !(child->bs->supported_zero_flags & BDRV_REQ_ALLOCATE))
+ {
+ return -ENOTSUP;
+ }
+
if (!(child->bs->open_flags & BDRV_O_UNMAP)) {
flags &= ~BDRV_REQ_MAY_UNMAP;
}
--
2.7.4
- Re: [Qemu-devel] [PATCH v4 08/15] qcow2: set inactive flag, (continued)
- [Qemu-devel] [PATCH v4 07/15] qcow2: preallocation at image expand, Anton Nefedov, 2017/08/01
- [Qemu-devel] [PATCH v4 01/15] mirror: inherit supported write/zero flags, Anton Nefedov, 2017/08/01
- [Qemu-devel] [PATCH v4 06/15] block: support BDRV_REQ_ALLOCATE in passthrough drivers, Anton Nefedov, 2017/08/01
- [Qemu-devel] [PATCH v4 05/15] file-posix: support BDRV_REQ_ALLOCATE, Anton Nefedov, 2017/08/01
- [Qemu-devel] [PATCH v4 09/15] qcow2: truncate preallocated space, Anton Nefedov, 2017/08/01
- [Qemu-devel] [PATCH v4 03/15] block: introduce BDRV_REQ_ALLOCATE flag,
Anton Nefedov <=
- [Qemu-devel] [PATCH v4 02/15] blkverify: set supported write/zero flags, Anton Nefedov, 2017/08/01
- [Qemu-devel] [PATCH v4 10/15] qcow2: check space leak at the end of the image, Anton Nefedov, 2017/08/01
- [Qemu-devel] [PATCH v4 15/15] iotest 134: test cluster-misaligned encrypted write, Anton Nefedov, 2017/08/01
- [Qemu-devel] [PATCH v4 13/15] qcow2: allocate image space by-cluster, Anton Nefedov, 2017/08/01
- [Qemu-devel] [PATCH v4 11/15] qcow2: move is_zero() up, Anton Nefedov, 2017/08/01
- [Qemu-devel] [PATCH v4 12/15] qcow2: skip writing zero buffers to empty COW areas, Anton Nefedov, 2017/08/01