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[Qemu-devel] [PATCHv5 13/17] block: introduce bdrv_make_zero
From: |
Peter Lieven |
Subject: |
[Qemu-devel] [PATCHv5 13/17] block: introduce bdrv_make_zero |
Date: |
Sun, 20 Oct 2013 17:43:07 +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 b28dd42..21a992a 100644
--- a/block.c
+++ b/block.c
@@ -2391,6 +2391,43 @@ 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 de0d6ab..8244adb 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);
--
1.7.9.5
- [Qemu-devel] [PATCHv5 02/17] block: add flags to bdrv_*_write_zeroes, (continued)
- [Qemu-devel] [PATCHv5 02/17] block: add flags to bdrv_*_write_zeroes, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 01/17] block: make BdrvRequestFlags public, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 03/17] block: introduce BDRV_REQ_MAY_UNMAP request flag, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 04/17] block: add logical block provisioning info to BlockDriverInfo, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 06/17] block/iscsi: add .bdrv_get_info, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 05/17] block: add wrappers for logical block provisioning information, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 07/17] block: add BlockLimits structure to BlockDriverState, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 09/17] block: honour BlockLimits in bdrv_co_discard, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 11/17] iscsi: set limits in BlockDriverState, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 08/17] block: honour BlockLimits in bdrv_co_do_write_zeroes, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 13/17] block: introduce bdrv_make_zero,
Peter Lieven <=
- [Qemu-devel] [PATCHv5 12/17] iscsi: add bdrv_co_write_zeroes, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 14/17] block/get_block_status: fix BDRV_BLOCK_ZERO for unallocated blocks, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 10/17] iscsi: simplify iscsi_co_discard, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 15/17] qemu-img: add support for fully allocated images, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 16/17] qemu-img: conditionally zero out target on convert, Peter Lieven, 2013/10/20
- [Qemu-devel] [PATCHv5 17/17] block/raw: copy BlockLimits on raw_open, Peter Lieven, 2013/10/20