block: Support BDRV_REQ_WRITE_UNCHANGED in filters

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 <[email protected]>
Reviewed-by: Stefan Hajnoczi <[email protected]>
Reviewed-by: Alberto Garcia <[email protected]>
Message-id: 20180421132929[email protected]
Reviewed-by: Kevin Wolf <[email protected]>
Signed-off-by: Max Reitz <[email protected]>

diff --git a/block/blkdebug.c b/block/blkdebug.c
index 053372c22ea26eb374900e5e14edfaa9562b8189..526af2a80843b28b80dff1291521eb9b3c367d6c 100644 (file)
--- 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 fe5a9b4a984da6a94b56a99391d4950363855748..b016dbeee75ad735196be43021fcda5e97b42699 100755 (executable)
--- 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 754cc9e85769c6921528c45d7ce5d86089bf1d30..da97ee592767b165c17d49c3addb05645bb3a8b7 100644 (file)
--- 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 823ec751c4036da65277b038e40ed91f7f662cb2..6a972088889f0502bfed89e8ec2a4da1440004ab 100644 (file)
--- 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 6aa38db1140093aaa21ca52d25b7e78fbdb59b71..a4197bb975c6ab29dd5a4ab6436de8dbf7532b3e 100644 (file)
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -1134,6 +1134,8 @@ 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 a378547c9983ae89558cd0a0fb557cb28d44f340..fe33693a2da2c511862e91c851e4ebd6f7238f40 100644 (file)
--- 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 95ed06acd8ddc61281d3d07c9eebfae568689b34..e298827f95e21f1f33ba3b8e3a5db675220031b2 100644 (file)
--- 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);
 }