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[Qemu-devel] [PULL 14/41] block: introduce bdrv_make_zero
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PULL 14/41] block: introduce bdrv_make_zero |
Date: |
Fri, 29 Nov 2013 17:45:29 +0100 |
From: Peter Lieven <address@hidden>
this patch adds a call to completely zero out a block device.
the operation is sped up by checking the block status and
only writing zeroes to the device if they currently do not
return zeroes. optionally the zero writing can be sped up
by setting the flag BDRV_REQ_MAY_UNMAP to emulate the zero
write by unmapping if the driver supports it.
Signed-off-by: Peter Lieven <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
block.c | 37 +++++++++++++++++++++++++++++++++++++
include/block/block.h | 1 +
2 files changed, 38 insertions(+)
diff --git a/block.c b/block.c
index df5a603..c390f20 100644
--- a/block.c
+++ b/block.c
@@ -2399,6 +2399,43 @@ int bdrv_write_zeroes(BlockDriverState *bs, int64_t
sector_num,
BDRV_REQ_ZERO_WRITE | flags);
}
+/*
+ * Completely zero out a block device with the help of bdrv_write_zeroes.
+ * The operation is sped up by checking the block status and only writing
+ * zeroes to the device if they currently do not return zeroes. Optional
+ * flags are passed through to bdrv_write_zeroes (e.g. BDRV_REQ_MAY_UNMAP).
+ *
+ * Returns < 0 on error, 0 on success. For error codes see bdrv_write().
+ */
+int bdrv_make_zero(BlockDriverState *bs, BdrvRequestFlags flags)
+{
+ int64_t target_size = bdrv_getlength(bs) / BDRV_SECTOR_SIZE;
+ int64_t ret, nb_sectors, sector_num = 0;
+ int n;
+
+ for (;;) {
+ nb_sectors = target_size - sector_num;
+ if (nb_sectors <= 0) {
+ return 0;
+ }
+ if (nb_sectors > INT_MAX) {
+ nb_sectors = INT_MAX;
+ }
+ ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &n);
+ if (ret & BDRV_BLOCK_ZERO) {
+ sector_num += n;
+ continue;
+ }
+ ret = bdrv_write_zeroes(bs, sector_num, n, flags);
+ if (ret < 0) {
+ error_report("error writing zeroes at sector %" PRId64 ": %s",
+ sector_num, strerror(-ret));
+ return ret;
+ }
+ sector_num += n;
+ }
+}
+
int bdrv_pread(BlockDriverState *bs, int64_t offset,
void *buf, int count1)
{
diff --git a/include/block/block.h b/include/block/block.h
index 803c5ca..4d9e67c 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -216,6 +216,7 @@ int bdrv_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors);
int bdrv_write_zeroes(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, BdrvRequestFlags flags);
+int bdrv_make_zero(BlockDriverState *bs, BdrvRequestFlags flags);
int bdrv_writev(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov);
int bdrv_pread(BlockDriverState *bs, int64_t offset,
void *buf, int count);
--
1.8.1.4
- [Qemu-devel] [PULL 03/41] block: introduce BDRV_REQ_MAY_UNMAP request flag, (continued)
- [Qemu-devel] [PULL 03/41] block: introduce BDRV_REQ_MAY_UNMAP request flag, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 07/41] block: add BlockLimits structure to BlockDriverState, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 06/41] block/iscsi: add .bdrv_get_info, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 05/41] block: add wrappers for logical block provisioning information, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 08/41] block/raw: copy BlockLimits on raw_open, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 09/41] block: honour BlockLimits in bdrv_co_do_write_zeroes, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 10/41] block: honour BlockLimits in bdrv_co_discard, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 11/41] iscsi: set limits in BlockDriverState, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 12/41] iscsi: simplify iscsi_co_discard, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 13/41] iscsi: add bdrv_co_write_zeroes, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 14/41] block: introduce bdrv_make_zero,
Kevin Wolf <=
- [Qemu-devel] [PULL 15/41] block/get_block_status: fix BDRV_BLOCK_ZERO for unallocated blocks, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 16/41] qemu-img: add support for fully allocated images, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 17/41] qemu-img: conditionally zero out target on convert, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 18/41] util/error: Save errno from clobbering, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 19/41] Test coroutine execution order, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 20/41] sheepdog: implement .bdrv_get_allocated_file_size, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 21/41] block/stream: Don't stream unbacked devices, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 22/41] block: per caller dirty bitmap, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 24/41] COW: Speed up writes, Kevin Wolf, 2013/11/29
- [Qemu-devel] [PULL 25/41] COW: Extend checking allocated bits to beyond one sector, Kevin Wolf, 2013/11/29