linux-ext4 - Re: [PATCH 8/8] ext4: remove unnecessary parameter "needed" in ext4_discard

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Date: Tue, 2 Jan 2024 14:10:58 +0100
From: Jan Kara <jack@...e.cz>
To: Kemeng Shi <shikemeng@...weicloud.com>
Cc: tytso@....edu, adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 8/8] ext4: remove unnecessary parameter "needed" in
 ext4_discard_preallocations

On Sun 26-11-23 00:11:43, Kemeng Shi wrote:
> The "needed" controls the number of ext4_prealloc_space to discard in
> ext4_discard_preallocations. Function ext4_discard_preallocations is
> supposed to discard all non-used preallocated blocks when "needed"
> is 0 and now ext4_discard_preallocations is always called with "needed"
> = 0. Remove unnecessary parameter "needed" and remove all non-used
> preallocated spaces in ext4_discard_preallocations to simplify the
> code.
> 
> Note: If count of non-used preallocated spaces could be more than
> UINT_MAX, there was a memory leak as some non-used preallocated
> spaces are left unused and this commit will fix it. Otherwise,
> there is no behavior change.
> 
> Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>

Looks good, just one nit:

> @@ -5491,15 +5491,12 @@ void ext4_discard_preallocations(struct inode *inode, unsigned int needed)
>  	mb_debug(sb, "discard preallocation for inode %lu\n",
>  		 inode->i_ino);
>  	trace_ext4_discard_preallocations(inode,
> -			atomic_read(&ei->i_prealloc_active), needed);
> -
> -	if (needed == 0)
> -		needed = UINT_MAX;
> +			atomic_read(&ei->i_prealloc_active), 0);

There's no point in always returning 0 in the tracepoint so I'd just update
it to not print the 'needed' value as well.

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR