linux-kernel - Re: [PATCH 1/2] btrfs: use min_t() for mismatched type comparison

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Message-ID: <1cfc2f43-8ea4-4c39-b543-1f54ba9b284e@suse.com>
Date: Wed, 26 Feb 2025 07:52:21 +1030
From: Qu Wenruo <wqu@...e.com>
To: Arnd Bergmann <arnd@...nel.org>, Chris Mason <clm@...com>,
 Josef Bacik <josef@...icpanda.com>, David Sterba <dsterba@...e.com>
Cc: Arnd Bergmann <arnd@...db.de>, kernel test robot <lkp@...el.com>,
 Johannes Thumshirn <johannes.thumshirn@....com>,
 Anand Jain <anand.jain@...cle.com>, Filipe Manana <fdmanana@...e.com>,
 Li Zetao <lizetao1@...wei.com>, linux-btrfs@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] btrfs: use min_t() for mismatched type comparison



在 2025/2/26 06:14, Arnd Bergmann 写道:
> From: Arnd Bergmann <arnd@...db.de>
> 
> loff_t is a signed type, so using min() to compare it against a u64
> causes a compiler warning:
> 
> fs/btrfs/extent_io.c:2497:13: error: call to '__compiletime_assert_728' declared with 'error' attribute: min(folio_pos(folio) + folio_size(folio) - 1, end) signedness error
>   2497 |                 cur_end = min(folio_pos(folio) + folio_size(folio) - 1, end);
>        |                           ^
> 
> Use min_t() instead.
> 
> Reported-by: kernel test robot <lkp@...el.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202502211908.aCcQQyEY-lkp@intel.com/
> Fixes: aba063bf9336 ("btrfs: prepare extent_io.c for future larger folio support")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Thanks a lot, those fixes will be merged into the next version.

For now the series is only for test purposes as there is a backlog of 
subpage block size related patches pending.

Thanks,
Qu

> ---
>   fs/btrfs/extent_io.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index f0a1da40d641..7dc996e7e249 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -2485,7 +2485,7 @@ void extent_write_locked_range(struct inode *inode, const struct folio *locked_f
>   		 * code is just in case, but shouldn't actually be run.
>   		 */
>   		if (IS_ERR(folio)) {
> -			cur_end = min(round_down(cur, PAGE_SIZE) + PAGE_SIZE - 1, end);
> +			cur_end = min_t(u64, round_down(cur, PAGE_SIZE) + PAGE_SIZE - 1, end);
>   			cur_len = cur_end + 1 - cur;
>   			btrfs_mark_ordered_io_finished(BTRFS_I(inode), NULL,
>   						       cur, cur_len, false);
> @@ -2494,7 +2494,7 @@ void extent_write_locked_range(struct inode *inode, const struct folio *locked_f
>   			continue;
>   		}
>   
> -		cur_end = min(folio_pos(folio) + folio_size(folio) - 1, end);
> +		cur_end = min_t(u64, folio_pos(folio) + folio_size(folio) - 1, end);
>   		cur_len = cur_end + 1 - cur;
>   
>   		ASSERT(folio_test_locked(folio));