Re: Fix an incorrect assertion condition in mdwritev(). - Mailing list pgsql-hackers

From Michael Paquier
Subject Re: Fix an incorrect assertion condition in mdwritev().
Date
Msg-id ZlKArtPhzn868no_@paquier.xyz
Whole thread Raw
In response to Fix an incorrect assertion condition in mdwritev().  (Xing Guo <higuoxing@gmail.com>)
Responses Re: Fix an incorrect assertion condition in mdwritev().
List pgsql-hackers
On Sat, May 25, 2024 at 11:52:22PM +0800, Xing Guo wrote:
> In commit 4908c58[^1], a vectored variant of smgrwrite() is added and
> the assertion condition in mdwritev() no longer matches the comment.
> This patch helps fix it.
>
>      /* This assert is too expensive to have on normally ... */
>  #ifdef CHECK_WRITE_VS_EXTEND
> -    Assert(blocknum < mdnblocks(reln, forknum));
> +    Assert(blocknum + nblocks <= mdnblocks(reln, forknum));
>  #endif

Yes, it looks like you're right that this can be made stricter,
computing the number of blocks we're adding in the number calculated
(aka adding one block to this number fails immediately at initdb).
--
Michael

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