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[Qemu-devel] [PATCHv2 13/20] block: introduce bdrv_zeroize
From: |
Peter Lieven |
Subject: |
[Qemu-devel] [PATCHv2 13/20] block: introduce bdrv_zeroize |
Date: |
Tue, 17 Sep 2013 15:48:49 +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 | 30 ++++++++++++++++++++++++++++++
include/block/block.h | 1 +
2 files changed, 31 insertions(+)
diff --git a/block.c b/block.c
index ecc5be4..88b137c 100644
--- a/block.c
+++ b/block.c
@@ -2342,6 +2342,36 @@ int bdrv_write_zeroes(BlockDriverState *bs, int64_t
sector_num,
BDRV_REQ_ZERO_WRITE | flags);
}
+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;
+ /* split the write requests into 1MB chunks if the driver
+ * does not return a maximal size via bdi */
+ 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 & BDRV_REQ_MAY_UNMAP);
+ if (ret < 0) {
+ error_report("error writing zeroes at sector %" PRId64 ": %s",
+ sector_num, strerror(-ret));
+ return -EIO;
+ }
+ 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 8aa325a..a45166e 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -195,6 +195,7 @@ 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] [PATCHv2 05/20] block/raw: add bdrv_has_discard_zeroes and bdrv_has_discard_write_zeroes, (continued)
- [Qemu-devel] [PATCHv2 05/20] block/raw: add bdrv_has_discard_zeroes and bdrv_has_discard_write_zeroes, Peter Lieven, 2013/09/17
- [Qemu-devel] [PATCHv2 11/20] iscsi: add bdrv_has_discard_zeroes and bdrv_has_discard_write_zeroes, Peter Lieven, 2013/09/17
- [Qemu-devel] [PATCHv2 12/20] iscsi: add bdrv_co_write_zeroes, Peter Lieven, 2013/09/17
- [Qemu-devel] [PATCHv2 07/20] block: honour alignment and limit in bdrv_co_do_write_zeroes, Peter Lieven, 2013/09/17
- [Qemu-devel] [PATCHv2 14/20] block/get_block_status: set *pnum = 0 on error, Peter Lieven, 2013/09/17
- [Qemu-devel] [PATCHv2 13/20] block: introduce bdrv_zeroize,
Peter Lieven <=
- [Qemu-devel] [PATCHv2 15/20] block/get_block_status: avoid segfault if there is no backing_hd, Peter Lieven, 2013/09/17
- [Qemu-devel] [PATCHv2 20/20] block/raw: copy block limits and alignment information on raw_open, Peter Lieven, 2013/09/17
- [Qemu-devel] [PATCHv2 17/20] block/get_block_status: fix BDRV_BLOCK_ZERO for unallocated blocks, Peter Lieven, 2013/09/17
- [Qemu-devel] [PATCHv2 19/20] qemu-img: conditionally zero out target on convert, Peter Lieven, 2013/09/17