| Message ID | 1379425736-11326-14-git-send-email-pl@kamp.de |
|---|---|
| State | New |
| Headers | show |
On 09/17/2013 07:48 AM, Peter Lieven wrote: > 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 <pl@kamp.de> > --- > 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) Please add documentation in the code base about what this function does, and what return values mean. (Bad practice in the past doesn't excuse new patches from being more maintainer-friendly) > +{ > + 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); Is this intentionally throwing away all other flags except BDRV_REQ_MAY_UNMAP?
Am 19.09.2013 um 22:26 schrieb Eric Blake <eblake@redhat.com>: > On 09/17/2013 07:48 AM, Peter Lieven wrote: >> 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 <pl@kamp.de> >> --- >> 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) > > Please add documentation in the code base about what this function does, > and what return values mean. (Bad practice in the past doesn't excuse > new patches from being more maintainer-friendly) ok ;-) > >> +{ >> + 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); > > Is this intentionally throwing away all other flags except > BDRV_REQ_MAY_UNMAP? This is the only option that bdrv_write_zeroes currently expects, but as this might change some day I don't mind to pass all flags. Peter
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);
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 <pl@kamp.de> --- block.c | 30 ++++++++++++++++++++++++++++++ include/block/block.h | 1 + 2 files changed, 31 insertions(+)