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Re: [PATCH for-5.0 2/2] block: Fix blk->in_flight during blk_wait_while_
From: |
Max Reitz |
Subject: |
Re: [PATCH for-5.0 2/2] block: Fix blk->in_flight during blk_wait_while_drained() |
Date: |
Fri, 3 Apr 2020 14:42:17 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 |
On 03.04.20 12:44, Kevin Wolf wrote:
> Calling blk_wait_while_drained() while blk->in_flight is increased for
> the current request is wrong because it will cause the drain operation
> to deadlock.
>
> Many callers of blk_wait_while_drained() have already increased
> blk->in_flight when called in a blk_aio_*() path, but can also be called
> in synchonous code paths where blk->in_flight isn't increased. This
> means that these calls of blk_wait_while_drained() are wrong at least in
> some cases.
>
> In order to fix this, increase blk->in_flight even for synchronous
> operations and temporarily decrease the counter again in
> blk_wait_while_drained().
>
> Fixes: cf3129323f900ef5ddbccbe86e4fa801e88c566e
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
> block/block-backend.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
blk_co_pdiscard() and blk_co_flush() are called from outside of
block-backend.c (namely from mirror.c and nbd/server.c). Is that OK?
Max
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