From f1b8961cbef828b62ba1ca7da79cd516f7dfc52b Mon Sep 17 00:00:00 2001 Message-Id: In-Reply-To: References: From: Paolo Bonzini Date: Mon, 9 Dec 2013 14:09:28 +0100 Subject: [PATCH 40/50] raw-posix: implement write_zeroes with MAY_UNMAP for block devices RH-Author: Paolo Bonzini Message-id: <1386598178-11845-43-git-send-email-pbonzini@redhat.com> Patchwork-id: 56079 O-Subject: [RHEL 7.0 qemu-kvm PATCH 42/52] raw-posix: implement write_zeroes with MAY_UNMAP for block devices Bugzilla: 1007815 RH-Acked-by: Jeffrey Cody RH-Acked-by: Fam Zheng RH-Acked-by: Stefan Hajnoczi 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 Signed-off-by: Stefan Hajnoczi (cherry picked from commit d0b4503ed2d8713791c38839341b023f78d1a3d9) --- block/raw-posix.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) Signed-off-by: Michal Novotny --- block/raw-posix.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/block/raw-posix.c b/block/raw-posix.c index ca5bcb3..815a80b 100644 --- a/block/raw-posix.c +++ b/block/raw-posix.c @@ -335,6 +335,22 @@ 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) { @@ -1637,6 +1673,7 @@ 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, -- 1.7.11.7