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Re: [Qemu-devel] [PATCH v6 16/42] block: Flush all children in generic c
From: |
Max Reitz |
Subject: |
Re: [Qemu-devel] [PATCH v6 16/42] block: Flush all children in generic code |
Date: |
Mon, 12 Aug 2019 14:58:16 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 |
On 10.08.19 17:36, Vladimir Sementsov-Ogievskiy wrote:
> 09.08.2019 19:13, Max Reitz wrote:
>> If the driver does not support .bdrv_co_flush() so bdrv_co_flush()
>> itself has to flush the children of the given node, it should not flush
>> just bs->file->bs, but in fact all children.
>>
>> In any case, the BLKDBG_EVENT() should be emitted on the primary child,
>> because that is where a blkdebug node would be if there is any.
>>
>> Suggested-by: Vladimir Sementsov-Ogievskiy <address@hidden>
>> Signed-off-by: Max Reitz <address@hidden>
>> ---
>> block/io.c | 23 +++++++++++++++++------
>> 1 file changed, 17 insertions(+), 6 deletions(-)
>>
>> diff --git a/block/io.c b/block/io.c
>> index c5a8e3e6a3..bcc770d336 100644
>> --- a/block/io.c
>> +++ b/block/io.c
>> @@ -2572,6 +2572,8 @@ static void coroutine_fn bdrv_flush_co_entry(void
>> *opaque)
>>
>> int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
>> {
>> + BdrvChild *primary_child = bdrv_primary_child(bs);
>> + BdrvChild *child;
>> int current_gen;
>> int ret = 0;
>>
>> @@ -2601,7 +2603,7 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
>> }
>>
>> /* Write back cached data to the OS even with cache=unsafe */
>> - BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_OS);
>> + BLKDBG_EVENT(primary_child, BLKDBG_FLUSH_TO_OS);
>> if (bs->drv->bdrv_co_flush_to_os) {
>> ret = bs->drv->bdrv_co_flush_to_os(bs);
>> if (ret < 0) {
>> @@ -2611,15 +2613,15 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
>>
>> /* But don't actually force it to the disk with cache=unsafe */
>> if (bs->open_flags & BDRV_O_NO_FLUSH) {
>> - goto flush_parent;
>> + goto flush_children;
>> }
>>
>> /* Check if we really need to flush anything */
>> if (bs->flushed_gen == current_gen) {
>> - goto flush_parent;
>> + goto flush_children;
>> }
>>
>> - BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_DISK);
>> + BLKDBG_EVENT(primary_child, BLKDBG_FLUSH_TO_DISK);
>> if (!bs->drv) {
>> /* bs->drv->bdrv_co_flush() might have ejected the BDS
>> * (even in case of apparent success) */
>> @@ -2663,8 +2665,17 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
>> /* Now flush the underlying protocol. It will also have
>> BDRV_O_NO_FLUSH
>> * in the case of cache=unsafe, so there are no useless flushes.
>> */
>> -flush_parent:
>> - ret = bs->file ? bdrv_co_flush(bs->file->bs) : 0;
>> +flush_children:
>> + ret = 0; > + QLIST_FOREACH(child, &bs->children, next) {
>> + int this_child_ret;
>> +
>> + this_child_ret = bdrv_co_flush(child->bs);
>> + if (!ret) {
>> + ret = this_child_ret;
>> + }
>> + }
>
> Hmm, you said that we want to flush only children with write-access from
> parent..
Good that you remember it, I must have overlooked it (when reading the
replies to the previous version). :-)
> Shouldn't we check it? Or we assume that it's always safe to call
> bdrv_co_flush on
> a node?
I think it’s always safe. But checking it seems like a nice touch, yes.
Max
>> +
>> out:
>> /* Notify any pending flushes that we have completed */
>> if (ret == 0) {
>>
>
>
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- Re: [Qemu-devel] [PATCH v6 09/42] block: Include filters when freezing backing chain, (continued)
- [Qemu-devel] [PATCH v6 11/42] block: Add bdrv_supports_compressed_writes(), Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 12/42] block: Use bdrv_filtered_rw* where obvious, Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 13/42] block: Use CAFs in block status functions, Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 14/42] block: Use CAFs when working with backing chains, Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 15/42] block: Re-evaluate backing file handling in reopen, Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 16/42] block: Flush all children in generic code, Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 17/42] block: Use CAFs in bdrv_refresh_limits(), Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 18/42] block: Use CAFs in bdrv_refresh_filename(), Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 19/42] block: Use CAF in bdrv_co_rw_vmstate(), Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 20/42] block/snapshot: Fix fallback, Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 21/42] block: Use CAFs for debug breakpoints, Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 22/42] block: Fix bdrv_get_allocated_file_size's fallback, Max Reitz, 2019/08/09