[PATCH v7 0/5] fix & merge block_status_above and is_allocated_above

[PATCH v7 0/5] fix & merge block_status_above and is_allocated_above

[Vladimir Sementsov-Ogievskiy]

Hi all!

These series are here to address the following problem:
block-status-above functions may consider space after EOF of
intermediate backing files as unallocated, which is wrong, as these
backing files are the reason of producing zeroes, we never go further by
backing chain after a short backing file. So, if such short-backing file
is _inside_ requested sub-chain of the backing chain, we should never
report space after its EOF as unallocated.

See patches 01,04,05 for details.

Note, that this series leaves for another day the general problem
around block-status: misuse of BDRV_BLOCK_ALLOCATED as is-fs-allocated
vs go-to-backing.
Audit for this problem is done here:
"backing chain & block status & filters"
https://lists.gnu.org/archive/html/qemu-devel/2020-04/msg04706.html
And I'm going to prepare series to address this problem.

Also, get_block_status func have same disease, but remains unfixed here:
I want to make separate series for it.

v7:
- add Alberto's r-bs in all patchs
- rebase to new backing-chain handling, bdrv_filter_or_cow_bs is used instead of backing_bs


Based on series "[PATCH v9 0/7] coroutines: generate wrapper code" or
in other words:
Based-on: <20200924185414.28642-1-vsementsov@virtuozzo.com>

Vladimir Sementsov-Ogievskiy (5):
  block/io: fix bdrv_co_block_status_above
  block/io: bdrv_common_block_status_above: support include_base
  block/io: bdrv_common_block_status_above: support bs == base
  block/io: fix bdrv_is_allocated_above
  iotests: add commit top->base cases to 274

 block/coroutines.h         |   2 +
 block/io.c                 | 132 +++++++++++++++++++++----------------
 block/qcow2.c              |  16 ++++-
 tests/qemu-iotests/274     |  20 ++++++
 tests/qemu-iotests/274.out |  68 +++++++++++++++++++
 5 files changed, 179 insertions(+), 59 deletions(-)

-- 
2.21.3

[PATCH v7 1/5] block/io: fix bdrv_co_block_status_above

[Vladimir Sementsov-Ogievskiy]

bdrv_co_block_status_above has several design problems with handling
short backing files:

1. With want_zeros=true, it may return ret with BDRV_BLOCK_ZERO but
without BDRV_BLOCK_ALLOCATED flag, when actually short backing file
which produces these after-EOF zeros is inside requested backing
sequence.

2. With want_zero=false, it may return pnum=0 prior to actual EOF,
because of EOF of short backing file.

Fix these things, making logic about short backing files clearer.

With fixed bdrv_block_status_above we also have to improve is_zero in
qcow2 code, otherwise iotest 154 will fail, because with this patch we
stop to merge zeros of different types (produced by fully unallocated
in the whole backing chain regions vs produced by short backing files).

Note also, that this patch leaves for another day the general problem
around block-status: misuse of BDRV_BLOCK_ALLOCATED as is-fs-allocated
vs go-to-backing.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
---
 block/io.c    | 68 ++++++++++++++++++++++++++++++++++++++++-----------
 block/qcow2.c | 16 ++++++++++--
 2 files changed, 68 insertions(+), 16 deletions(-)

diff --git a/block/io.c b/block/io.c
index 449b99b92c..4697e67a85 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2350,34 +2350,74 @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
                                   int64_t *map,
                                   BlockDriverState **file)
 {
+    int ret;
     BlockDriverState *p;
-    int ret = 0;
-    bool first = true;
+    int64_t eof = 0;
 
     assert(bs != base);
-    for (p = bs; p != base; p = bdrv_filter_or_cow_bs(p)) {
+
+    ret = bdrv_co_block_status(bs, want_zero, offset, bytes, pnum, map, file);
+    if (ret < 0 || *pnum == 0 || ret & BDRV_BLOCK_ALLOCATED) {
+        return ret;
+    }
+
+    if (ret & BDRV_BLOCK_EOF) {
+        eof = offset + *pnum;
+    }
+
+    assert(*pnum <= bytes);
+    bytes = *pnum;
+
+    for (p = bdrv_filter_or_cow_bs(bs); p != base;
+         p = bdrv_filter_or_cow_bs(p))
+    {
         ret = bdrv_co_block_status(p, want_zero, offset, bytes, pnum, map,
                                    file);
         if (ret < 0) {
-            break;
+            return ret;
         }
-        if (ret & BDRV_BLOCK_ZERO && ret & BDRV_BLOCK_EOF && !first) {
+        if (*pnum == 0) {
             /*
-             * Reading beyond the end of the file continues to read
-             * zeroes, but we can only widen the result to the
-             * unallocated length we learned from an earlier
-             * iteration.
+             * The top layer deferred to this layer, and because this layer is
+             * short, any zeroes that we synthesize beyond EOF behave as if they
+             * were allocated at this layer.
+             *
+             * We don't include BDRV_BLOCK_EOF into ret, as upper layer may be
+             * larger. We'll add BDRV_BLOCK_EOF if needed at function end, see
+             * below.
              */
+            assert(ret & BDRV_BLOCK_EOF);
             *pnum = bytes;
+            if (file) {
+                *file = p;
+            }
+            ret = BDRV_BLOCK_ZERO | BDRV_BLOCK_ALLOCATED;
+            break;
         }
-        if (ret & (BDRV_BLOCK_ZERO | BDRV_BLOCK_DATA)) {
+        if (ret & BDRV_BLOCK_ALLOCATED) {
+            /*
+             * We've found the node and the status, we must break.
+             *
+             * Drop BDRV_BLOCK_EOF, as it's not for upper layer, which may be
+             * larger. We'll add BDRV_BLOCK_EOF if needed at function end, see
+             * below.
+             */
+            ret &= ~BDRV_BLOCK_EOF;
             break;
         }
-        /* [offset, pnum] unallocated on this layer, which could be only
-         * the first part of [offset, bytes].  */
-        bytes = MIN(bytes, *pnum);
-        first = false;
+
+        /*
+         * OK, [offset, offset + *pnum) region is unallocated on this layer,
+         * let's continue the diving.
+         */
+        assert(*pnum <= bytes);
+        bytes = *pnum;
     }
+
+    if (offset + *pnum == eof) {
+        ret |= BDRV_BLOCK_EOF;
+    }
+
     return ret;
 }
 
diff --git a/block/qcow2.c b/block/qcow2.c
index b05512718c..a1bc16e202 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3860,8 +3860,20 @@ static bool is_zero(BlockDriverState *bs, int64_t offset, int64_t bytes)
     if (!bytes) {
         return true;
     }
-    res = bdrv_block_status_above(bs, NULL, offset, bytes, &nr, NULL, NULL);
-    return res >= 0 && (res & BDRV_BLOCK_ZERO) && nr == bytes;
+
+    /*
+     * bdrv_block_status_above doesn't merge different types of zeros, for
+     * example, zeros which come from the region which is unallocated in
+     * the whole backing chain, and zeros which comes because of a short
+     * backing file. So, we need a loop.
+     */
+    do {
+        res = bdrv_block_status_above(bs, NULL, offset, bytes, &nr, NULL, NULL);
+        offset += nr;
+        bytes -= nr;
+    } while (res >= 0 && (res & BDRV_BLOCK_ZERO) && nr && bytes);
+
+    return res >= 0 && (res & BDRV_BLOCK_ZERO) && bytes == 0;
 }
 
 static coroutine_fn int qcow2_co_pwrite_zeroes(BlockDriverState *bs,
-- 
2.21.3

[PATCH v7 2/5] block/io: bdrv_common_block_status_above: support include_base

[Vladimir Sementsov-Ogievskiy]

In order to reuse bdrv_common_block_status_above in
bdrv_is_allocated_above, let's support include_base parameter.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
---
 block/coroutines.h |  2 ++
 block/io.c         | 21 ++++++++++++++-------
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/block/coroutines.h b/block/coroutines.h
index f69179f5ef..1cb3128b94 100644
--- a/block/coroutines.h
+++ b/block/coroutines.h
@@ -41,6 +41,7 @@ bdrv_pwritev(BdrvChild *child, int64_t offset, unsigned int bytes,
 int coroutine_fn
 bdrv_co_common_block_status_above(BlockDriverState *bs,
                                   BlockDriverState *base,
+                                  bool include_base,
                                   bool want_zero,
                                   int64_t offset,
                                   int64_t bytes,
@@ -50,6 +51,7 @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
 int generated_co_wrapper
 bdrv_common_block_status_above(BlockDriverState *bs,
                                BlockDriverState *base,
+                               bool include_base,
                                bool want_zero,
                                int64_t offset,
                                int64_t bytes,
diff --git a/block/io.c b/block/io.c
index 4697e67a85..b88c7a6314 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2343,6 +2343,7 @@ early_out:
 int coroutine_fn
 bdrv_co_common_block_status_above(BlockDriverState *bs,
                                   BlockDriverState *base,
+                                  bool include_base,
                                   bool want_zero,
                                   int64_t offset,
                                   int64_t bytes,
@@ -2354,10 +2355,11 @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
     BlockDriverState *p;
     int64_t eof = 0;
 
-    assert(bs != base);
+    assert(include_base || bs != base);
+    assert(!include_base || base); /* Can't include NULL base */
 
     ret = bdrv_co_block_status(bs, want_zero, offset, bytes, pnum, map, file);
-    if (ret < 0 || *pnum == 0 || ret & BDRV_BLOCK_ALLOCATED) {
+    if (ret < 0 || *pnum == 0 || ret & BDRV_BLOCK_ALLOCATED || bs == base) {
         return ret;
     }
 
@@ -2368,7 +2370,7 @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
     assert(*pnum <= bytes);
     bytes = *pnum;
 
-    for (p = bdrv_filter_or_cow_bs(bs); p != base;
+    for (p = bdrv_filter_or_cow_bs(bs); include_base || p != base;
          p = bdrv_filter_or_cow_bs(p))
     {
         ret = bdrv_co_block_status(p, want_zero, offset, bytes, pnum, map,
@@ -2406,6 +2408,11 @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
             break;
         }
 
+        if (p == base) {
+            assert(include_base);
+            break;
+        }
+
         /*
          * OK, [offset, offset + *pnum) region is unallocated on this layer,
          * let's continue the diving.
@@ -2425,7 +2432,7 @@ int bdrv_block_status_above(BlockDriverState *bs, BlockDriverState *base,
                             int64_t offset, int64_t bytes, int64_t *pnum,
                             int64_t *map, BlockDriverState **file)
 {
-    return bdrv_common_block_status_above(bs, base, true, offset, bytes,
+    return bdrv_common_block_status_above(bs, base, false, true, offset, bytes,
                                           pnum, map, file);
 }
 
@@ -2442,9 +2449,9 @@ int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset,
     int ret;
     int64_t dummy;
 
-    ret = bdrv_common_block_status_above(bs, bdrv_filter_or_cow_bs(bs), false,
-                                         offset, bytes, pnum ? pnum : &dummy,
-                                         NULL, NULL);
+    ret = bdrv_common_block_status_above(bs, bs, true, false, offset,
+                                         bytes, pnum ? pnum : &dummy, NULL,
+                                         NULL);
     if (ret < 0) {
         return ret;
     }
-- 
2.21.3

[PATCH v7 3/5] block/io: bdrv_common_block_status_above: support bs == base

[Vladimir Sementsov-Ogievskiy]

We are going to reuse bdrv_common_block_status_above in
bdrv_is_allocated_above. bdrv_is_allocated_above may be called with
include_base == false and still bs == base (for ex. from img_rebase()).

So, support this corner case.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
---
 block/io.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/block/io.c b/block/io.c
index b88c7a6314..82a3afa3dc 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2355,9 +2355,13 @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
     BlockDriverState *p;
     int64_t eof = 0;
 
-    assert(include_base || bs != base);
     assert(!include_base || base); /* Can't include NULL base */
 
+    if (!include_base && bs == base) {
+        *pnum = bytes;
+        return 0;
+    }
+
     ret = bdrv_co_block_status(bs, want_zero, offset, bytes, pnum, map, file);
     if (ret < 0 || *pnum == 0 || ret & BDRV_BLOCK_ALLOCATED || bs == base) {
         return ret;
-- 
2.21.3

[PATCH v7 4/5] block/io: fix bdrv_is_allocated_above

[Vladimir Sementsov-Ogievskiy]

bdrv_is_allocated_above wrongly handles short backing files: it reports
after-EOF space as UNALLOCATED which is wrong, as on read the data is
generated on the level of short backing file (if all overlays has
unallocated area at that place).

Reusing bdrv_common_block_status_above fixes the issue and unifies code
path.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
---
 block/io.c | 43 +++++--------------------------------------
 1 file changed, 5 insertions(+), 38 deletions(-)

diff --git a/block/io.c b/block/io.c
index 82a3afa3dc..36baf4fed4 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2477,52 +2477,19 @@ int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset,
  * at 'offset + *pnum' may return the same allocation status (in other
  * words, the result is not necessarily the maximum possible range);
  * but 'pnum' will only be 0 when end of file is reached.
- *
  */
 int bdrv_is_allocated_above(BlockDriverState *top,
                             BlockDriverState *base,
                             bool include_base, int64_t offset,
                             int64_t bytes, int64_t *pnum)
 {
-    BlockDriverState *intermediate;
-    int ret;
-    int64_t n = bytes;
-
-    assert(base || !include_base);
-
-    intermediate = top;
-    while (include_base || intermediate != base) {
-        int64_t pnum_inter;
-        int64_t size_inter;
-
-        assert(intermediate);
-        ret = bdrv_is_allocated(intermediate, offset, bytes, &pnum_inter);
-        if (ret < 0) {
-            return ret;
-        }
-        if (ret) {
-            *pnum = pnum_inter;
-            return 1;
-        }
-
-        size_inter = bdrv_getlength(intermediate);
-        if (size_inter < 0) {
-            return size_inter;
-        }
-        if (n > pnum_inter &&
-            (intermediate == top || offset + pnum_inter < size_inter)) {
-            n = pnum_inter;
-        }
-
-        if (intermediate == base) {
-            break;
-        }
-
-        intermediate = bdrv_filter_or_cow_bs(intermediate);
+    int ret = bdrv_common_block_status_above(top, base, include_base, false,
+                                             offset, bytes, pnum, NULL, NULL);
+    if (ret < 0) {
+        return ret;
     }
 
-    *pnum = n;
-    return 0;
+    return !!(ret & BDRV_BLOCK_ALLOCATED);
 }
 
 int coroutine_fn
-- 
2.21.3

[PATCH v7 5/5] iotests: add commit top->base cases to 274

[Vladimir Sementsov-Ogievskiy]

These cases are fixed by previous patches around block_status and
is_allocated.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
---
 tests/qemu-iotests/274     | 20 +++++++++++
 tests/qemu-iotests/274.out | 68 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 88 insertions(+)

diff --git a/tests/qemu-iotests/274 b/tests/qemu-iotests/274
index d4571c5465..76b1ba6a52 100755
--- a/tests/qemu-iotests/274
+++ b/tests/qemu-iotests/274
@@ -115,6 +115,26 @@ with iotests.FilePath('base') as base, \
     iotests.qemu_io_log('-c', 'read -P 1 0 %d' % size_short, mid)
     iotests.qemu_io_log('-c', 'read -P 0 %d %d' % (size_short, size_diff), mid)
 
+    iotests.log('=== Testing qemu-img commit (top -> base) ===')
+
+    create_chain()
+    iotests.qemu_img_log('commit', '-b', base, top)
+    iotests.img_info_log(base)
+    iotests.qemu_io_log('-c', 'read -P 1 0 %d' % size_short, base)
+    iotests.qemu_io_log('-c', 'read -P 0 %d %d' % (size_short, size_diff), base)
+
+    iotests.log('=== Testing QMP active commit (top -> base) ===')
+
+    create_chain()
+    with create_vm() as vm:
+        vm.launch()
+        vm.qmp_log('block-commit', device='top', base_node='base',
+                   job_id='job0', auto_dismiss=False)
+        vm.run_job('job0', wait=5)
+
+    iotests.img_info_log(mid)
+    iotests.qemu_io_log('-c', 'read -P 1 0 %d' % size_short, base)
+    iotests.qemu_io_log('-c', 'read -P 0 %d %d' % (size_short, size_diff), base)
 
     iotests.log('== Resize tests ==')
 
diff --git a/tests/qemu-iotests/274.out b/tests/qemu-iotests/274.out
index bf5abd4c10..cfe17a8659 100644
--- a/tests/qemu-iotests/274.out
+++ b/tests/qemu-iotests/274.out
@@ -135,6 +135,74 @@ read 1048576/1048576 bytes at offset 0
 read 1048576/1048576 bytes at offset 1048576
 1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
+=== Testing qemu-img commit (top -> base) ===
+Formatting 'TEST_DIR/PID-base', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=2097152 lazy_refcounts=off refcount_bits=16
+
+Formatting 'TEST_DIR/PID-mid', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1048576 backing_file=TEST_DIR/PID-base backing_fmt=qcow2 lazy_refcounts=off refcount_bits=16
+
+Formatting 'TEST_DIR/PID-top', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=2097152 backing_file=TEST_DIR/PID-mid backing_fmt=qcow2 lazy_refcounts=off refcount_bits=16
+
+wrote 2097152/2097152 bytes at offset 0
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+Image committed.
+
+image: TEST_IMG
+file format: IMGFMT
+virtual size: 2 MiB (2097152 bytes)
+cluster_size: 65536
+Format specific information:
+    compat: 1.1
+    compression type: zlib
+    lazy refcounts: false
+    refcount bits: 16
+    corrupt: false
+    extended l2: false
+
+read 1048576/1048576 bytes at offset 0
+1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+read 1048576/1048576 bytes at offset 1048576
+1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+=== Testing QMP active commit (top -> base) ===
+Formatting 'TEST_DIR/PID-base', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=2097152 lazy_refcounts=off refcount_bits=16
+
+Formatting 'TEST_DIR/PID-mid', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1048576 backing_file=TEST_DIR/PID-base backing_fmt=qcow2 lazy_refcounts=off refcount_bits=16
+
+Formatting 'TEST_DIR/PID-top', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=2097152 backing_file=TEST_DIR/PID-mid backing_fmt=qcow2 lazy_refcounts=off refcount_bits=16
+
+wrote 2097152/2097152 bytes at offset 0
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+{"execute": "block-commit", "arguments": {"auto-dismiss": false, "base-node": "base", "device": "top", "job-id": "job0"}}
+{"return": {}}
+{"execute": "job-complete", "arguments": {"id": "job0"}}
+{"return": {}}
+{"data": {"device": "job0", "len": 1048576, "offset": 1048576, "speed": 0, "type": "commit"}, "event": "BLOCK_JOB_READY", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
+{"data": {"device": "job0", "len": 1048576, "offset": 1048576, "speed": 0, "type": "commit"}, "event": "BLOCK_JOB_COMPLETED", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
+{"execute": "job-dismiss", "arguments": {"id": "job0"}}
+{"return": {}}
+image: TEST_IMG
+file format: IMGFMT
+virtual size: 1 MiB (1048576 bytes)
+cluster_size: 65536
+backing file: TEST_DIR/PID-base
+backing file format: IMGFMT
+Format specific information:
+    compat: 1.1
+    compression type: zlib
+    lazy refcounts: false
+    refcount bits: 16
+    corrupt: false
+    extended l2: false
+
+read 1048576/1048576 bytes at offset 0
+1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+read 1048576/1048576 bytes at offset 1048576
+1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
 == Resize tests ==
 === preallocation=off ===
 Formatting 'TEST_DIR/PID-base', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=6442450944 lazy_refcounts=off refcount_bits=16
-- 
2.21.3

Re: [PATCH v7 1/5] block/io: fix bdrv_co_block_status_above

[Eric Blake]

On 9/24/20 2:39 PM, Vladimir Sementsov-Ogievskiy wrote:
> bdrv_co_block_status_above has several design problems with handling
> short backing files:
> 
> 1. With want_zeros=true, it may return ret with BDRV_BLOCK_ZERO but
> without BDRV_BLOCK_ALLOCATED flag, when actually short backing file
> which produces these after-EOF zeros is inside requested backing
> sequence.
> 
> 2. With want_zero=false, it may return pnum=0 prior to actual EOF,
> because of EOF of short backing file.
> 
> Fix these things, making logic about short backing files clearer.
> 
> With fixed bdrv_block_status_above we also have to improve is_zero in
> qcow2 code, otherwise iotest 154 will fail, because with this patch we
> stop to merge zeros of different types (produced by fully unallocated
> in the whole backing chain regions vs produced by short backing files).
> 
> Note also, that this patch leaves for another day the general problem
> around block-status: misuse of BDRV_BLOCK_ALLOCATED as is-fs-allocated
> vs go-to-backing.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Reviewed-by: Alberto Garcia <berto@igalia.com>
> ---
>   block/io.c    | 68 ++++++++++++++++++++++++++++++++++++++++-----------
>   block/qcow2.c | 16 ++++++++++--
>   2 files changed, 68 insertions(+), 16 deletions(-)
> 
> diff --git a/block/io.c b/block/io.c
> index 449b99b92c..4697e67a85 100644
> --- a/block/io.c
> +++ b/block/io.c
> @@ -2350,34 +2350,74 @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
>                                     int64_t *map,
>                                     BlockDriverState **file)
>   {
> +    int ret;
>       BlockDriverState *p;
> -    int ret = 0;

The shuffle of these lines is odd, but not a show-stopper.

The new flow is definitely easier to read.  Thanks for doing this!

> +++ b/block/qcow2.c
> @@ -3860,8 +3860,20 @@ static bool is_zero(BlockDriverState *bs, int64_t offset, int64_t bytes)
>       if (!bytes) {
>           return true;
>       }
> -    res = bdrv_block_status_above(bs, NULL, offset, bytes, &nr, NULL, NULL);
> -    return res >= 0 && (res & BDRV_BLOCK_ZERO) && nr == bytes;
> +
> +    /*
> +     * bdrv_block_status_above doesn't merge different types of zeros, for

We're inconsistent on whether we spell the noun 'zeros' or 'zeroes'; but 
I don't care enough to make you change this.

> +     * example, zeros which come from the region which is unallocated in
> +     * the whole backing chain, and zeros which comes because of a short

s/comes/come/

> +     * backing file. So, we need a loop.
> +     */
> +    do {
> +        res = bdrv_block_status_above(bs, NULL, offset, bytes, &nr, NULL, NULL);
> +        offset += nr;
> +        bytes -= nr;
> +    } while (res >= 0 && (res & BDRV_BLOCK_ZERO) && nr && bytes);
> +
> +    return res >= 0 && (res & BDRV_BLOCK_ZERO) && bytes == 0;
>   }
>   
>   static coroutine_fn int qcow2_co_pwrite_zeroes(BlockDriverState *bs,
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

Re: [PATCH v7 2/5] block/io: bdrv_common_block_status_above: support include_base

[Eric Blake]

On 9/24/20 2:40 PM, Vladimir Sementsov-Ogievskiy wrote:
> In order to reuse bdrv_common_block_status_above in
> bdrv_is_allocated_above, let's support include_base parameter.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Reviewed-by: Alberto Garcia <berto@igalia.com>
> ---
>   block/coroutines.h |  2 ++
>   block/io.c         | 21 ++++++++++++++-------
>   2 files changed, 16 insertions(+), 7 deletions(-)
> 

> +++ b/block/io.c
> @@ -2343,6 +2343,7 @@ early_out:
>   int coroutine_fn
>   bdrv_co_common_block_status_above(BlockDriverState *bs,
>                                     BlockDriverState *base,
> +                                  bool include_base,
>                                     bool want_zero,
>                                     int64_t offset,
>                                     int64_t bytes,
> @@ -2354,10 +2355,11 @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
>       BlockDriverState *p;
>       int64_t eof = 0;
>   
> -    assert(bs != base);
> +    assert(include_base || bs != base);
> +    assert(!include_base || base); /* Can't include NULL base */

I wonder if this would be easier to read as:

if (include_base) {
     assert(bs != base);
} else {
     assert(base); /* Can't include NULL base */
}

but I won't insist.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

Re: [PATCH v7 4/5] block/io: fix bdrv_is_allocated_above

[Eric Blake]

On 9/24/20 2:40 PM, Vladimir Sementsov-Ogievskiy wrote:
> bdrv_is_allocated_above wrongly handles short backing files: it reports
> after-EOF space as UNALLOCATED which is wrong, as on read the data is
> generated on the level of short backing file (if all overlays has

s/has/have/

> unallocated area at that place).
> 
> Reusing bdrv_common_block_status_above fixes the issue and unifies code
> path.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> Reviewed-by: Alberto Garcia <berto@igalia.com>
> ---
>   block/io.c | 43 +++++--------------------------------------
>   1 file changed, 5 insertions(+), 38 deletions(-)

Nice diffstat, R-b remains in force.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

Re: [PATCH v7 0/5] fix & merge block_status_above and is_allocated_above

[no-reply]

Patchew URL: https://patchew.org/QEMU/20200924194003.22080-1-vsementsov@virtuozzo.com/



Hi,

This series failed the docker-quick@centos7 build test. Please find the testing commands and
their output below. If you have Docker installed, you can probably reproduce it
locally.

=== TEST SCRIPT BEGIN ===
#!/bin/bash
make docker-image-centos7 V=1 NETWORK=1
time make docker-test-quick@centos7 SHOW_ENV=1 J=14 NETWORK=1
=== TEST SCRIPT END ===

C linker for the host machine: cc ld.bfd 2.27-43
Host machine cpu family: x86_64
Host machine cpu: x86_64
../src/meson.build:10: WARNING: Module unstable-keyval has no backwards or forwards compatibility and might not exist in future releases.
Program sh found: YES
Program python3 found: YES (/usr/bin/python3)
Configuring ninjatool using configuration
---
    return codecs.ascii_decode(input, self.errors)[0]
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 11406: ordinal not in range(128)
Generating 'libqemu-aarch64-softmmu.fa.p/decode-neon-shared.c.inc'.
make: *** [block/block-gen.c.stamp] Error 1
make: *** Waiting for unfinished jobs....
Traceback (most recent call last):
  File "./tests/docker/docker.py", line 709, in <module>
---
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['sudo', '-n', 'docker', 'run', '--rm', '--label', 'com.qemu.instance.uuid=528b329e049d459c994676e3ba6dc69a', '-u', '1003', '--security-opt', 'seccomp=unconfined', '-e', 'TARGET_LIST=', '-e', 'EXTRA_CONFIGURE_OPTS=', '-e', 'V=', '-e', 'J=14', '-e', 'DEBUG=', '-e', 'SHOW_ENV=1', '-e', 'CCACHE_DIR=/var/tmp/ccache', '-v', '/home/patchew2/.cache/qemu-docker-ccache:/var/tmp/ccache:z', '-v', '/var/tmp/patchew-tester-tmp-e72243g9/src/docker-src.2020-09-24-17.42.11.20907:/var/tmp/qemu:z,ro', 'qemu/centos7', '/var/tmp/qemu/run', 'test-quick']' returned non-zero exit status 2.
filter=--filter=label=com.qemu.instance.uuid=528b329e049d459c994676e3ba6dc69a
make[1]: *** [docker-run] Error 1
make[1]: Leaving directory `/var/tmp/patchew-tester-tmp-e72243g9/src'
make: *** [docker-run-test-quick@centos7] Error 2

real    3m12.373s
user    0m16.084s


The full log is available at
http://patchew.org/logs/20200924194003.22080-1-vsementsov@virtuozzo.com/testing.docker-quick@centos7/?type=message.
---
Email generated automatically by Patchew [https://patchew.org/].
Please send your feedback to patchew-devel@redhat.com

Re: [PATCH v7 0/5] fix & merge block_status_above and is_allocated_above

[Vladimir Sementsov-Ogievskiy]

It's all because underlying "[PATCH v9 0/7] coroutines: generate wrapper code" series, I've answered in "[PATCH v9 0/7] coroutines: generate wrapper code" thread.

25.09.2020 00:45, no-reply@patchew.org wrote:
> Patchew URL: https://patchew.org/QEMU/20200924194003.22080-1-vsementsov@virtuozzo.com/
> 
> 
> 
> Hi,
> 
> This series failed the docker-quick@centos7 build test. Please find the testing commands and
> their output below. If you have Docker installed, you can probably reproduce it
> locally.
> 
> === TEST SCRIPT BEGIN ===
> #!/bin/bash
> make docker-image-centos7 V=1 NETWORK=1
> time make docker-test-quick@centos7 SHOW_ENV=1 J=14 NETWORK=1
> === TEST SCRIPT END ===
> 
> C linker for the host machine: cc ld.bfd 2.27-43
> Host machine cpu family: x86_64
> Host machine cpu: x86_64
> ../src/meson.build:10: WARNING: Module unstable-keyval has no backwards or forwards compatibility and might not exist in future releases.
> Program sh found: YES
> Program python3 found: YES (/usr/bin/python3)
> Configuring ninjatool using configuration
> ---
>      return codecs.ascii_decode(input, self.errors)[0]
> UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 11406: ordinal not in range(128)
> Generating 'libqemu-aarch64-softmmu.fa.p/decode-neon-shared.c.inc'.
> make: *** [block/block-gen.c.stamp] Error 1
> make: *** Waiting for unfinished jobs....
> Traceback (most recent call last):
>    File "./tests/docker/docker.py", line 709, in <module>
> ---
>      raise CalledProcessError(retcode, cmd)
> subprocess.CalledProcessError: Command '['sudo', '-n', 'docker', 'run', '--rm', '--label', 'com.qemu.instance.uuid=528b329e049d459c994676e3ba6dc69a', '-u', '1003', '--security-opt', 'seccomp=unconfined', '-e', 'TARGET_LIST=', '-e', 'EXTRA_CONFIGURE_OPTS=', '-e', 'V=', '-e', 'J=14', '-e', 'DEBUG=', '-e', 'SHOW_ENV=1', '-e', 'CCACHE_DIR=/var/tmp/ccache', '-v', '/home/patchew2/.cache/qemu-docker-ccache:/var/tmp/ccache:z', '-v', '/var/tmp/patchew-tester-tmp-e72243g9/src/docker-src.2020-09-24-17.42.11.20907:/var/tmp/qemu:z,ro', 'qemu/centos7', '/var/tmp/qemu/run', 'test-quick']' returned non-zero exit status 2.
> filter=--filter=label=com.qemu.instance.uuid=528b329e049d459c994676e3ba6dc69a
> make[1]: *** [docker-run] Error 1
> make[1]: Leaving directory `/var/tmp/patchew-tester-tmp-e72243g9/src'
> make: *** [docker-run-test-quick@centos7] Error 2
> 
> real    3m12.373s
> user    0m16.084s
> 
> 
> The full log is available at
> http://patchew.org/logs/20200924194003.22080-1-vsementsov@virtuozzo.com/testing.docker-quick@centos7/?type=message.
> ---
> Email generated automatically by Patchew [https://patchew.org/].
> Please send your feedback to patchew-devel@redhat.com
> 


-- 
Best regards,
Vladimir

Re: [PATCH v7 0/5] fix & merge block_status_above and is_allocated_above

[Stefan Hajnoczi]

[-- Attachment #1: Type: text/plain, Size: 2189 bytes --]

On Thu, Sep 24, 2020 at 10:39:58PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> Hi all!
> 
> These series are here to address the following problem:
> block-status-above functions may consider space after EOF of
> intermediate backing files as unallocated, which is wrong, as these
> backing files are the reason of producing zeroes, we never go further by
> backing chain after a short backing file. So, if such short-backing file
> is _inside_ requested sub-chain of the backing chain, we should never
> report space after its EOF as unallocated.
> 
> See patches 01,04,05 for details.
> 
> Note, that this series leaves for another day the general problem
> around block-status: misuse of BDRV_BLOCK_ALLOCATED as is-fs-allocated
> vs go-to-backing.
> Audit for this problem is done here:
> "backing chain & block status & filters"
> https://lists.gnu.org/archive/html/qemu-devel/2020-04/msg04706.html
> And I'm going to prepare series to address this problem.
> 
> Also, get_block_status func have same disease, but remains unfixed here:
> I want to make separate series for it.
> 
> v7:
> - add Alberto's r-bs in all patchs
> - rebase to new backing-chain handling, bdrv_filter_or_cow_bs is used instead of backing_bs
> 
> 
> Based on series "[PATCH v9 0/7] coroutines: generate wrapper code" or
> in other words:
> Based-on: <20200924185414.28642-1-vsementsov@virtuozzo.com>
> 
> Vladimir Sementsov-Ogievskiy (5):
>   block/io: fix bdrv_co_block_status_above
>   block/io: bdrv_common_block_status_above: support include_base
>   block/io: bdrv_common_block_status_above: support bs == base
>   block/io: fix bdrv_is_allocated_above
>   iotests: add commit top->base cases to 274
> 
>  block/coroutines.h         |   2 +
>  block/io.c                 | 132 +++++++++++++++++++++----------------
>  block/qcow2.c              |  16 ++++-
>  tests/qemu-iotests/274     |  20 ++++++
>  tests/qemu-iotests/274.out |  68 +++++++++++++++++++
>  5 files changed, 179 insertions(+), 59 deletions(-)
> 
> -- 
> 2.21.3
> 

Thanks, applied to my block tree with Eric's spelling fixes:
https://github.com/stefanha/qemu/commits/block

Stefan

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