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raw-posix: implement write_zeroes with MAY_UNMAP for block devices

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See the next commit for the description of the Linux kernel problem
that is worked around in raw_open_common.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Paolo Bonzini 2013-11-22 13:39:56 +01:00 committed by Stefan Hajnoczi
parent 260a82e524
commit d0b4503ed2
1 changed files with 37 additions and 0 deletions
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37
block/raw-posix.c
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@ -334,6 +334,22 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
if (S_ISREG(st.st_mode)) {
s->discard_zeroes = true;
}
if (S_ISBLK(st.st_mode)) {
#ifdef BLKDISCARDZEROES
unsigned int arg;
if (ioctl(s->fd, BLKDISCARDZEROES, &arg) == 0 && arg) {
s->discard_zeroes = true;
}
#endif
#ifdef __linux__
/* On Linux 3.10, BLKDISCARD leaves stale data in the page cache. Do
* not rely on the contents of discarded blocks unless using O_DIRECT.
*/
if (!(bs->open_flags & BDRV_O_NOCACHE)) {
s->discard_zeroes = false;
}
#endif
}
#ifdef CONFIG_XFS
if (platform_test_xfs_fd(s->fd)) {
@ -1586,6 +1602,26 @@ static coroutine_fn BlockDriverAIOCB *hdev_aio_discard(BlockDriverState *bs,
cb, opaque, QEMU_AIO_DISCARD|QEMU_AIO_BLKDEV);
}
static coroutine_fn int hdev_co_write_zeroes(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, BdrvRequestFlags flags)
{
BDRVRawState *s = bs->opaque;
int rc;
rc = fd_open(bs);
if (rc < 0) {
return rc;
}
if (!(flags & BDRV_REQ_MAY_UNMAP)) {
return -ENOTSUP;
}
if (!s->discard_zeroes) {
return -ENOTSUP;
}
return paio_submit_co(bs, s->fd, sector_num, NULL, nb_sectors,
QEMU_AIO_DISCARD|QEMU_AIO_BLKDEV);
}
static int hdev_create(const char *filename, QEMUOptionParameter *options,
Error **errp)
{
@ -1638,6 +1674,7 @@ static BlockDriver bdrv_host_device = {
.bdrv_reopen_abort = raw_reopen_abort,
.bdrv_create = hdev_create,
.create_options = raw_create_options,
.bdrv_co_write_zeroes = hdev_co_write_zeroes,
.bdrv_aio_readv = raw_aio_readv,
.bdrv_aio_writev = raw_aio_writev,