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From: William Baker <williamtbakeremail@gmail.com>
To: Junio C Hamano <gitster@pobox.com>,
	Kevin Willford <Kevin.Willford@microsoft.com>
Cc: Utsav Shah via GitGitGadget <gitgitgadget@gmail.com>,
	William Baker <William.Baker@microsoft.com>,
	"git@vger.kernel.org" <git@vger.kernel.org>,
	Utsav Shah <ukshah2@illinois.edu>
Subject: Re: [PATCH 0/1] fsmonitor: skip sanity check if the index is split
Date: Thu, 14 Nov 2019 08:41:25 -0800	[thread overview]
Message-ID: <beb5a2b4-f07c-c3fd-9e68-dbee85fba2ee@gmail.com> (raw)
In-Reply-To: <xmqqzhh0d0ma.fsf@gitster-ct.c.googlers.com>


On 11/12/19 5:30 PM, Junio C Hamano wrote:
> Thanks.  Here is what I came up with to tie the loose ends of this
> thread.
> 
> -- >8 --
> From: Junio C Hamano <gitster@pobox.com>
> Subject: [PATCH] fsmonitor: do not compare bitmap size with size of split index
> 
> 3444ec2e ("fsmonitor: don't fill bitmap with entries to be removed",
> 2019-10-11) added a handful of sanity checks that make sure that a
> bit position in fsmonitor bitmap does not go beyond the end of the
> index.  As each bit in the bitmap corresponds to a path in the
> index, this is the right check most of the time.
> 
> Except for the case when we are in the split-index mode and looking
> at a delta index that is to be overlayed on the base index but
> before the base index has actually been merged in, namely in read_
> and write_fsmonitor_extension().  In these codepaths, the entries in
> the split/delta index is typically a small subset of the entire set
> of paths (otherwise why would we be using split-index?), so the
> bitmap used by the fsmonitor is almost always larger than the number
> of entries in the partial index, and the incorrect comparison would
> trigger the BUG().
> 
> Reported-by: Utsav Shah <ukshah2@illinois.edu>
> Helped-by: Kevin Willford <Kevin.Willford@microsoft.com>
> Helped-by: William Baker <William.Baker@microsoft.com>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  fsmonitor.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fsmonitor.c b/fsmonitor.c
> index 1f4aa1b150..0477500b39 100644
> --- a/fsmonitor.c
> +++ b/fsmonitor.c
> @@ -55,7 +55,8 @@ int read_fsmonitor_extension(struct index_state *istate, const void *data,
>  	}
>  	istate->fsmonitor_dirty = fsmonitor_dirty;
>  
> -	if (istate->fsmonitor_dirty->bit_size > istate->cache_nr)
> +	if (!istate->split_index &&
> +	    istate->fsmonitor_dirty->bit_size > istate->cache_nr)
>  		BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
>  		    (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr);
>  
> @@ -83,7 +84,8 @@ void write_fsmonitor_extension(struct strbuf *sb, struct index_state *istate)
>  	uint32_t ewah_size = 0;
>  	int fixup = 0;
>  
> -	if (istate->fsmonitor_dirty->bit_size > istate->cache_nr)
> +	if (!istate->split_index &&
> +	    istate->fsmonitor_dirty->bit_size > istate->cache_nr)
>  		BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
>  		    (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr);
>  
> 

This looks good to me.

Thanks,
William

  parent reply	other threads:[~2019-11-14 16:41 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-08  7:09 Utsav Shah via GitGitGadget
2019-11-08  7:09 ` [PATCH 1/1] " Utsav Shah via GitGitGadget
2019-11-12 11:18   ` SZEDER Gábor
2019-11-12 21:08     ` Utsav Shah
2019-11-11  1:43 ` [PATCH 0/1] " Junio C Hamano
2019-11-11  2:01   ` Junio C Hamano
2019-11-11 16:55     ` Kevin Willford
2019-11-11 17:25       ` Utsav Shah
2019-11-11 18:21         ` Kevin Willford
2019-11-11 17:30       ` William Baker
2019-11-13  1:30       ` Junio C Hamano
2019-11-14  2:55         ` Utsav Shah
2019-11-14 16:41         ` William Baker [this message]
2019-11-15  5:04           ` Junio C Hamano

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