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[Qemu-devel] [PATCHv3 13/20] block: introduce bdrv_zeroize
From: |
Peter Lieven |
Subject: |
[Qemu-devel] [PATCHv3 13/20] block: introduce bdrv_zeroize |
Date: |
Tue, 24 Sep 2013 15:35:07 +0200 |
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>
---
block.c | 37 +++++++++++++++++++++++++++++++++++++
include/block/block.h | 1 +
2 files changed, 38 insertions(+)
diff --git a/block.c b/block.c
index 784e545..66b9eae 100644
--- a/block.c
+++ b/block.c
@@ -2398,6 +2398,43 @@ 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_zeroize(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 2de226f..e059188 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -196,6 +196,7 @@ 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_zeroize(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);
--
1.7.9.5
- [Qemu-devel] [PATCHv3 00/20] block: logical block provisioning enhancements, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 04/20] block: introduce bdrv_has_discard_zeroes and bdrv_has_discard_write_zeroes, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 01/20] block: make BdrvRequestFlags public, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 02/20] block: add flags to bdrv_*_write_zeroes, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 03/20] block: introduce BDRV_REQ_MAY_UNMAP request flag, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 05/20] block/raw: add bdrv_has_discard_zeroes and bdrv_has_discard_write_zeroes, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 06/20] block: add BlockLimits structure to BlockDriverState, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 07/20] block: honour BlockLimits in bdrv_co_do_write_zeroes, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 08/20] block: honour BlockLimits in bdrv_co_discard, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 11/20] iscsi: add bdrv_has_discard_zeroes and bdrv_has_discard_write_zeroes, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 13/20] block: introduce bdrv_zeroize,
Peter Lieven <=
- [Qemu-devel] [PATCHv3 12/20] iscsi: add bdrv_co_write_zeroes, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 10/20] iscsi: set limits in BlockDriverState, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 14/20] block/get_block_status: set *pnum = 0 on error, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 09/20] iscsi: simplify iscsi_co_discard, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 16/20] block/get_block_status: avoid redundant callouts on raw devices, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 18/20] qemu-img: add support for fully allocated images, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 20/20] block/raw: copy BlockLimits on raw_open, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 15/20] block/get_block_status: avoid segfault if there is no backing_hd, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 17/20] block/get_block_status: fix BDRV_BLOCK_ZERO for unallocated blocks, Peter Lieven, 2013/09/24
- [Qemu-devel] [PATCHv3 19/20] qemu-img: conditionally zero out target on convert, Peter Lieven, 2013/09/24