From c8f8c2859899c631415825beee9cb6369e302f43 Mon Sep 17 00:00:00 2001 Message-Id: In-Reply-To: References: From: Paolo Bonzini Date: Mon, 9 Dec 2013 14:08:56 +0100 Subject: [PATCH 08/50] block: introduce BDRV_REQ_MAY_UNMAP request flag RH-Author: Paolo Bonzini Message-id: <1386598178-11845-11-git-send-email-pbonzini@redhat.com> Patchwork-id: 56047 O-Subject: [RHEL 7.0 qemu-kvm PATCH 10/52] block: introduce BDRV_REQ_MAY_UNMAP request flag Bugzilla: 1007815 RH-Acked-by: Jeffrey Cody RH-Acked-by: Fam Zheng RH-Acked-by: Stefan Hajnoczi From: Peter Lieven Reviewed-by: Eric Blake Signed-off-by: Peter Lieven Signed-off-by: Stefan Hajnoczi (cherry picked from commit d32f35cbc5a87af5e1100dd55074a79fc2cb5307) Conflicts: block/backup.c [missing] --- block-migration.c | 3 ++- block.c | 4 ++++ include/block/block.h | 7 +++++++ 3 files changed, 13 insertions(+), 1 deletion(-) Signed-off-by: Michal Novotny --- block-migration.c | 3 ++- block.c | 4 ++++ include/block/block.h | 7 +++++++ 3 files changed, 13 insertions(+), 1 deletion(-) diff --git a/block-migration.c b/block-migration.c index 3b22db6..1844066 100644 --- a/block-migration.c +++ b/block-migration.c @@ -780,7 +780,8 @@ static int block_load(QEMUFile *f, void *opaque, int version_id) } if (flags & BLK_MIG_FLAG_ZERO_BLOCK) { - ret = bdrv_write_zeroes(bs, addr, nr_sectors, 0); + ret = bdrv_write_zeroes(bs, addr, nr_sectors, + BDRV_REQ_MAY_UNMAP); } else { buf = g_malloc(BLOCK_SIZE); qemu_get_buffer(f, buf, BLOCK_SIZE); diff --git a/block.c b/block.c index 698334a..77167f0 100644 --- a/block.c +++ b/block.c @@ -2827,6 +2827,10 @@ int coroutine_fn bdrv_co_write_zeroes(BlockDriverState *bs, { trace_bdrv_co_write_zeroes(bs, sector_num, nb_sectors); + if (!(bs->open_flags & BDRV_O_UNMAP)) { + flags &= ~BDRV_REQ_MAY_UNMAP; + } + return bdrv_co_do_writev(bs, sector_num, nb_sectors, NULL, BDRV_REQ_ZERO_WRITE | flags); } diff --git a/include/block/block.h b/include/block/block.h index 2d78a84..10abc00 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -65,6 +65,13 @@ typedef struct BlockDevOps { typedef enum { BDRV_REQ_COPY_ON_READ = 0x1, BDRV_REQ_ZERO_WRITE = 0x2, + /* The BDRV_REQ_MAY_UNMAP flag is used to indicate that the block driver + * is allowed to optimize a write zeroes request by unmapping (discarding) + * blocks if it is guaranteed that the result will read back as + * zeroes. The flag is only passed to the driver if the block device is + * opened with BDRV_O_UNMAP. + */ + BDRV_REQ_MAY_UNMAP = 0x4, } BdrvRequestFlags; #define BDRV_O_RDWR 0x0002 -- 1.7.11.7