| From 69e802baf506bd21a2f444cfebe4ac7f5b5d07a8 Mon Sep 17 00:00:00 2001 |
| Message-Id: <69e802baf506bd21a2f444cfebe4ac7f5b5d07a8.1389014116.git.minovotn@redhat.com> |
| In-Reply-To: <c8cc35838d42aa286242772d97e3a9be7bb786ba.1389014116.git.minovotn@redhat.com> |
| References: <c8cc35838d42aa286242772d97e3a9be7bb786ba.1389014116.git.minovotn@redhat.com> |
| From: Paolo Bonzini <pbonzini@redhat.com> |
| Date: Mon, 9 Dec 2013 14:09:02 +0100 |
| Subject: [PATCH 14/50] block: honour BlockLimits in bdrv_co_do_write_zeroes |
| |
| RH-Author: Paolo Bonzini <pbonzini@redhat.com> |
| Message-id: <1386598178-11845-17-git-send-email-pbonzini@redhat.com> |
| Patchwork-id: 56052 |
| O-Subject: [RHEL 7.0 qemu-kvm PATCH 16/52] block: honour BlockLimits in bdrv_co_do_write_zeroes |
| Bugzilla: 1007815 |
| RH-Acked-by: Jeffrey Cody <jcody@redhat.com> |
| RH-Acked-by: Fam Zheng <famz@redhat.com> |
| RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com> |
| |
| From: Peter Lieven <pl@kamp.de> |
| |
| Reviewed-by: Eric Blake <eblake@redhat.com> |
| Signed-off-by: Peter Lieven <pl@kamp.de> |
| Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> |
| (cherry picked from commit c31cb70728d2c0c8900b35a66784baa446fd5147) |
| |
| block.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++---------------- |
| 1 file changed, 49 insertions(+), 16 deletions(-) |
| |
| Signed-off-by: Michal Novotny <minovotn@redhat.com> |
| |
| block.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++---------------- |
| 1 file changed, 49 insertions(+), 16 deletions(-) |
| |
| diff --git a/block.c b/block.c |
| index 2fae459..2ed9aa9 100644 |
| |
| |
| @@ -2724,32 +2724,65 @@ int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs, |
| BDRV_REQ_COPY_ON_READ); |
| } |
| |
| +/* if no limit is specified in the BlockLimits use a default |
| + * of 32768 512-byte sectors (16 MiB) per request. |
| + */ |
| +#define MAX_WRITE_ZEROES_DEFAULT 32768 |
| + |
| static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs, |
| int64_t sector_num, int nb_sectors, BdrvRequestFlags flags) |
| { |
| BlockDriver *drv = bs->drv; |
| QEMUIOVector qiov; |
| - struct iovec iov; |
| - int ret; |
| + struct iovec iov = {0}; |
| + int ret = 0; |
| |
| - /* TODO Emulate only part of misaligned requests instead of letting block |
| - * drivers return -ENOTSUP and emulate everything */ |
| + int max_write_zeroes = bs->bl.max_write_zeroes ? |
| + bs->bl.max_write_zeroes : MAX_WRITE_ZEROES_DEFAULT; |
| |
| - /* First try the efficient write zeroes operation */ |
| - if (drv->bdrv_co_write_zeroes) { |
| - ret = drv->bdrv_co_write_zeroes(bs, sector_num, nb_sectors, flags); |
| - if (ret != -ENOTSUP) { |
| - return ret; |
| + while (nb_sectors > 0 && !ret) { |
| + int num = nb_sectors; |
| + |
| + /* align request */ |
| + if (bs->bl.write_zeroes_alignment && |
| + num >= bs->bl.write_zeroes_alignment && |
| + sector_num % bs->bl.write_zeroes_alignment) { |
| + if (num > bs->bl.write_zeroes_alignment) { |
| + num = bs->bl.write_zeroes_alignment; |
| + } |
| + num -= sector_num % bs->bl.write_zeroes_alignment; |
| } |
| - } |
| |
| - /* Fall back to bounce buffer if write zeroes is unsupported */ |
| - iov.iov_len = nb_sectors * BDRV_SECTOR_SIZE; |
| - iov.iov_base = qemu_blockalign(bs, iov.iov_len); |
| - memset(iov.iov_base, 0, iov.iov_len); |
| - qemu_iovec_init_external(&qiov, &iov, 1); |
| + /* limit request size */ |
| + if (num > max_write_zeroes) { |
| + num = max_write_zeroes; |
| + } |
| + |
| + ret = -ENOTSUP; |
| + /* First try the efficient write zeroes operation */ |
| + if (drv->bdrv_co_write_zeroes) { |
| + ret = drv->bdrv_co_write_zeroes(bs, sector_num, num, flags); |
| + } |
| + |
| + if (ret == -ENOTSUP) { |
| + /* Fall back to bounce buffer if write zeroes is unsupported */ |
| + iov.iov_len = num * BDRV_SECTOR_SIZE; |
| + if (iov.iov_base == NULL) { |
| + /* allocate bounce buffer only once and ensure that it |
| + * is big enough for this and all future requests. |
| + */ |
| + size_t bufsize = num <= nb_sectors ? num : max_write_zeroes; |
| + iov.iov_base = qemu_blockalign(bs, bufsize * BDRV_SECTOR_SIZE); |
| + memset(iov.iov_base, 0, bufsize * BDRV_SECTOR_SIZE); |
| + } |
| + qemu_iovec_init_external(&qiov, &iov, 1); |
| |
| - ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, &qiov); |
| + ret = drv->bdrv_co_writev(bs, sector_num, num, &qiov); |
| + } |
| + |
| + sector_num += num; |
| + nb_sectors -= num; |
| + } |
| |
| qemu_vfree(iov.iov_base); |
| return ret; |
| -- |
| 1.7.11.7 |
| |