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From c8f8c2859899c631415825beee9cb6369e302f43 Mon Sep 17 00:00:00 2001
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Message-Id: <c8f8c2859899c631415825beee9cb6369e302f43.1389014116.git.minovotn@redhat.com>
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In-Reply-To: <c8cc35838d42aa286242772d97e3a9be7bb786ba.1389014116.git.minovotn@redhat.com>
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References: <c8cc35838d42aa286242772d97e3a9be7bb786ba.1389014116.git.minovotn@redhat.com>
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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Mon, 9 Dec 2013 14:08:56 +0100
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Subject: [PATCH 08/50] block: introduce BDRV_REQ_MAY_UNMAP request flag
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RH-Author: Paolo Bonzini <pbonzini@redhat.com>
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Message-id: <1386598178-11845-11-git-send-email-pbonzini@redhat.com>
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Patchwork-id: 56047
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O-Subject: [RHEL 7.0 qemu-kvm PATCH 10/52] block: introduce BDRV_REQ_MAY_UNMAP request flag
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Bugzilla: 1007815
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RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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From: Peter Lieven <pl@kamp.de>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Signed-off-by: Peter Lieven <pl@kamp.de>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit d32f35cbc5a87af5e1100dd55074a79fc2cb5307)
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Conflicts:
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block/backup.c [missing]
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---
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block-migration.c | 3 ++-
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block.c | 4 ++++
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include/block/block.h | 7 +++++++
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3 files changed, 13 insertions(+), 1 deletion(-)
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Signed-off-by: Michal Novotny <minovotn@redhat.com>
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---
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block-migration.c | 3 ++-
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block.c | 4 ++++
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include/block/block.h | 7 +++++++
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3 files changed, 13 insertions(+), 1 deletion(-)
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diff --git a/block-migration.c b/block-migration.c
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index 3b22db6..1844066 100644
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--- a/block-migration.c
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+++ b/block-migration.c
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@@ -780,7 +780,8 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
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}
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if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
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- ret = bdrv_write_zeroes(bs, addr, nr_sectors, 0);
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+ ret = bdrv_write_zeroes(bs, addr, nr_sectors,
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+ BDRV_REQ_MAY_UNMAP);
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} else {
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buf = g_malloc(BLOCK_SIZE);
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qemu_get_buffer(f, buf, BLOCK_SIZE);
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diff --git a/block.c b/block.c
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index 698334a..77167f0 100644
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--- a/block.c
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+++ b/block.c
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@@ -2827,6 +2827,10 @@ int coroutine_fn bdrv_co_write_zeroes(BlockDriverState *bs,
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{
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trace_bdrv_co_write_zeroes(bs, sector_num, nb_sectors);
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+ if (!(bs->open_flags & BDRV_O_UNMAP)) {
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+ flags &= ~BDRV_REQ_MAY_UNMAP;
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+ }
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+
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return bdrv_co_do_writev(bs, sector_num, nb_sectors, NULL,
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BDRV_REQ_ZERO_WRITE | flags);
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}
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diff --git a/include/block/block.h b/include/block/block.h
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index 2d78a84..10abc00 100644
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--- a/include/block/block.h
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+++ b/include/block/block.h
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@@ -65,6 +65,13 @@ typedef struct BlockDevOps {
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typedef enum {
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BDRV_REQ_COPY_ON_READ = 0x1,
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BDRV_REQ_ZERO_WRITE = 0x2,
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+ /* The BDRV_REQ_MAY_UNMAP flag is used to indicate that the block driver
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+ * is allowed to optimize a write zeroes request by unmapping (discarding)
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+ * blocks if it is guaranteed that the result will read back as
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+ * zeroes. The flag is only passed to the driver if the block device is
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+ * opened with BDRV_O_UNMAP.
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+ */
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+ BDRV_REQ_MAY_UNMAP = 0x4,
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} BdrvRequestFlags;
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#define BDRV_O_RDWR 0x0002
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--
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1.7.11.7
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