From 9cecd3548e9275e7de21801b90c277c7b04cabb4 Mon Sep 17 00:00:00 2001

From: Max Reitz <mreitz@redhat.com>

Date: Mon, 18 Jun 2018 16:12:09 +0200

Subject: [PATCH 042/268] block: Support BDRV_REQ_WRITE_UNCHANGED in filters

RH-Author: Max Reitz <mreitz@redhat.com>

Message-id: <20180618161212.14444-8-mreitz@redhat.com>

Patchwork-id: 80767

O-Subject: [RHV-7.6 qemu-kvm-rhev PATCH 07/10] block: Support BDRV_REQ_WRITE_UNCHANGED in filters

Bugzilla: 1518738

RH-Acked-by: John Snow <jsnow@redhat.com>

RH-Acked-by: Kevin Wolf <kwolf@redhat.com>

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

Update the rest of the filter drivers to support

BDRV_REQ_WRITE_UNCHANGED.  They already forward write request flags to

their children, so we just have to announce support for it.

This patch does not cover the replication driver because that currently

does not support flags at all, and because it just grabs the WRITE

permission for its children when it can, so we should be fine just

submitting the incoming WRITE_UNCHANGED requests as normal writes.

It also does not cover format drivers for similar reasons.  They all use

bdrv_format_default_perms() as their .bdrv_child_perm() implementation

so they just always grab the WRITE permission for their file children

whenever possible.  In addition, it often would be difficult to

ascertain whether incoming unchanging writes end up as unchanging writes

in their files.  So we just leave them as normal potentially changing

writes.

Signed-off-by: Max Reitz <mreitz@redhat.com>

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: Alberto Garcia <berto@igalia.com>

Message-id: 20180421132929.21610-7-mreitz@redhat.com

Reviewed-by: Kevin Wolf <kwolf@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>

(cherry picked from commit 228345bf5db8bc97d1c64f062e138d389065d1ab)

Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 block/blkdebug.c     |  9 +++++----

 block/blkreplay.c    |  3 +++

 block/blkverify.c    |  3 +++

 block/copy-on-read.c | 10 ++++++----

 block/mirror.c       |  2 ++

 block/raw-format.c   |  9 +++++----

 block/throttle.c     |  6 ++++--

 7 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/block/blkdebug.c b/block/blkdebug.c

index 053372c..526af2a 100644

--- a/block/blkdebug.c

+++ b/block/blkdebug.c

@@ -398,10 +398,11 @@ static int blkdebug_open(BlockDriverState *bs, QDict *options, int flags,

         goto out;

     }

-    bs->supported_write_flags = BDRV_REQ_FUA &

-        bs->file->bs->supported_write_flags;

-    bs->supported_zero_flags = (BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &

-        bs->file->bs->supported_zero_flags;

+    bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |

+        (BDRV_REQ_FUA & bs->file->bs->supported_write_flags);

+    bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |

+        ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &

+            bs->file->bs->supported_zero_flags);

     ret = -EINVAL;

     /* Set alignment overrides */

diff --git a/block/blkreplay.c b/block/blkreplay.c

index fe5a9b4..b016dbe 100755

--- a/block/blkreplay.c

+++ b/block/blkreplay.c

@@ -35,6 +35,9 @@ static int blkreplay_open(BlockDriverState *bs, QDict *options, int flags,

         goto fail;

     }

+    bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED;

+    bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED;

+

     ret = 0;

 fail:

     return ret;

diff --git a/block/blkverify.c b/block/blkverify.c

index 754cc9e..da97ee5 100644

--- a/block/blkverify.c

+++ b/block/blkverify.c

@@ -141,6 +141,9 @@ static int blkverify_open(BlockDriverState *bs, QDict *options, int flags,

         goto fail;

     }

+    bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED;

+    bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED;

+

     ret = 0;

 fail:

     qemu_opts_del(opts);

diff --git a/block/copy-on-read.c b/block/copy-on-read.c

index 823ec75..6a97208 100644

--- a/block/copy-on-read.c

+++ b/block/copy-on-read.c

@@ -33,11 +33,13 @@ static int cor_open(BlockDriverState *bs, QDict *options, int flags,

         return -EINVAL;

     }

-    bs->supported_write_flags = BDRV_REQ_FUA &

-                                    bs->file->bs->supported_write_flags;

+    bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |

+                                (BDRV_REQ_FUA &

+                                    bs->file->bs->supported_write_flags);

-    bs->supported_zero_flags = (BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &

-                                    bs->file->bs->supported_zero_flags;

+    bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |

+                               ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &

+                                    bs->file->bs->supported_zero_flags);

     return 0;

 }

diff --git a/block/mirror.c b/block/mirror.c

index 99da9c0..003f957 100644

--- a/block/mirror.c

+++ b/block/mirror.c

@@ -1152,6 +1152,8 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,

         mirror_top_bs->implicit = true;

     }

     mirror_top_bs->total_sectors = bs->total_sectors;

+    mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED;

+    mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED;

     bdrv_set_aio_context(mirror_top_bs, bdrv_get_aio_context(bs));

     /* bdrv_append takes ownership of the mirror_top_bs reference, need to keep

diff --git a/block/raw-format.c b/block/raw-format.c

index a378547..fe33693 100644

--- a/block/raw-format.c

+++ b/block/raw-format.c

@@ -415,10 +415,11 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,

     }

     bs->sg = bs->file->bs->sg;

-    bs->supported_write_flags = BDRV_REQ_FUA &

-        bs->file->bs->supported_write_flags;

-    bs->supported_zero_flags = (BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &

-        bs->file->bs->supported_zero_flags;

+    bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |

+        (BDRV_REQ_FUA & bs->file->bs->supported_write_flags);

+    bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |

+        ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &

+            bs->file->bs->supported_zero_flags);

     if (bs->probed && !bdrv_is_read_only(bs)) {

         fprintf(stderr,

diff --git a/block/throttle.c b/block/throttle.c

index 95ed06a..e298827 100644

--- a/block/throttle.c

+++ b/block/throttle.c

@@ -81,8 +81,10 @@ static int throttle_open(BlockDriverState *bs, QDict *options,

     if (!bs->file) {

         return -EINVAL;

     }

-    bs->supported_write_flags = bs->file->bs->supported_write_flags;

-    bs->supported_zero_flags = bs->file->bs->supported_zero_flags;

+    bs->supported_write_flags = bs->file->bs->supported_write_flags |

+                                BDRV_REQ_WRITE_UNCHANGED;

+    bs->supported_zero_flags = bs->file->bs->supported_zero_flags |

+                               BDRV_REQ_WRITE_UNCHANGED;

     return throttle_configure_tgm(bs, tgm, options, errp);

 }

-- 

1.8.3.1