linux-kernel - Re: [PATCH] ocfs2: replace usage of found with dedicated list iterator variable

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Date:   Fri, 25 Mar 2022 11:15:24 +0800
From:   Joseph Qi <joseph.qi@...ux.alibaba.com>
To:     Jakob Koschel <jakobkoschel@...il.com>,
        Mark Fasheh <mark@...heh.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Joel Becker <jlbec@...lplan.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Miguel Ojeda <ojeda@...nel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        ocfs2-devel@....oracle.com, linux-kernel@...r.kernel.org,
        Mike Rapoport <rppt@...nel.org>,
        Brian Johannesmeyer <bjohannesmeyer@...il.com>,
        Cristiano Giuffrida <c.giuffrida@...nl>,
        "Bos, H.J." <h.j.bos@...nl>
Subject: Re: [PATCH] ocfs2: replace usage of found with dedicated list
 iterator variable



On 3/24/22 3:16 PM, Jakob Koschel wrote:
> To move the list iterator variable into the list_for_each_entry_*()
> macro in the future it should be avoided to use the list iterator
> variable after the loop body.
> 
> To *never* use the list iterator variable after the loop it was
> concluded to use a separate iterator variable instead of a
> found boolean [1].
> 
> This removes the need to use a found variable and simply checking if
> the variable was set, can determine if the break/goto was hit.
> 
> Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/
> Signed-off-by: Jakob Koschel <jakobkoschel@...il.com>

Looks good.
Reviewed-by: Joseph Qi <joseph.qi@...ux.alibaba.com>

> ---
>  fs/ocfs2/dlm/dlmunlock.c | 21 ++++++++++-----------
>  fs/ocfs2/quota_local.c   | 10 +++++-----
>  2 files changed, 15 insertions(+), 16 deletions(-)
> 
> diff --git a/fs/ocfs2/dlm/dlmunlock.c b/fs/ocfs2/dlm/dlmunlock.c
> index 61103b2d69fb..7318e4794ef9 100644
> --- a/fs/ocfs2/dlm/dlmunlock.c
> +++ b/fs/ocfs2/dlm/dlmunlock.c
> @@ -392,9 +392,9 @@ int dlm_unlock_lock_handler(struct o2net_msg *msg, u32 len, void *data,
>  	struct dlm_ctxt *dlm = data;
>  	struct dlm_unlock_lock *unlock = (struct dlm_unlock_lock *)msg->buf;
>  	struct dlm_lock_resource *res = NULL;
> -	struct dlm_lock *lock = NULL;
> +	struct dlm_lock *lock = NULL, *iter;
>  	enum dlm_status status = DLM_NORMAL;
> -	int found = 0, i;
> +	int i;
>  	struct dlm_lockstatus *lksb = NULL;
>  	int ignore;
>  	u32 flags;
> @@ -437,7 +437,6 @@ int dlm_unlock_lock_handler(struct o2net_msg *msg, u32 len, void *data,
>  	}
>  
>  	queue=&res->granted;
> -	found = 0;
>  	spin_lock(&res->spinlock);
>  	if (res->state & DLM_LOCK_RES_RECOVERING) {
>  		spin_unlock(&res->spinlock);
> @@ -461,21 +460,21 @@ int dlm_unlock_lock_handler(struct o2net_msg *msg, u32 len, void *data,
>  	}
>  
>  	for (i=0; i<3; i++) {
> -		list_for_each_entry(lock, queue, list) {
> -			if (lock->ml.cookie == unlock->cookie &&
> -		    	    lock->ml.node == unlock->node_idx) {
> -				dlm_lock_get(lock);
> -				found = 1;
> +		list_for_each_entry(iter, queue, list) {
> +			if (iter->ml.cookie == unlock->cookie &&
> +			    iter->ml.node == unlock->node_idx) {
> +				dlm_lock_get(iter);
> +				lock = iter;
>  				break;
>  			}
>  		}
> -		if (found)
> +		if (lock)
>  			break;
>  		/* scan granted -> converting -> blocked queues */
>  		queue++;
>  	}
>  	spin_unlock(&res->spinlock);
> -	if (!found) {
> +	if (!lock) {
>  		status = DLM_IVLOCKID;
>  		goto not_found;
>  	}
> @@ -505,7 +504,7 @@ int dlm_unlock_lock_handler(struct o2net_msg *msg, u32 len, void *data,
>  	dlm_kick_thread(dlm, res);
>  
>  not_found:
> -	if (!found)
> +	if (!lock)
>  		mlog(ML_ERROR, "failed to find lock to unlock! "
>  			       "cookie=%u:%llu\n",
>  		     dlm_get_lock_cookie_node(be64_to_cpu(unlock->cookie)),
> diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
> index 0e4b16d4c037..38cc75bd3127 100644
> --- a/fs/ocfs2/quota_local.c
> +++ b/fs/ocfs2/quota_local.c
> @@ -923,19 +923,19 @@ static struct ocfs2_quota_chunk *ocfs2_find_free_entry(struct super_block *sb,
>  {
>  	struct mem_dqinfo *info = sb_dqinfo(sb, type);
>  	struct ocfs2_mem_dqinfo *oinfo = info->dqi_priv;
> -	struct ocfs2_quota_chunk *chunk;
> +	struct ocfs2_quota_chunk *chunk = NULL, *iter;
>  	struct ocfs2_local_disk_chunk *dchunk;
>  	int found = 0, len;
>  
> -	list_for_each_entry(chunk, &oinfo->dqi_chunk, qc_chunk) {
> +	list_for_each_entry(iter, &oinfo->dqi_chunk, qc_chunk) {
>  		dchunk = (struct ocfs2_local_disk_chunk *)
> -						chunk->qc_headerbh->b_data;
> +						iter->qc_headerbh->b_data;
>  		if (le32_to_cpu(dchunk->dqc_free) > 0) {
> -			found = 1;
> +			chunk = iter;
>  			break;
>  		}
>  	}
> -	if (!found)
> +	if (!chunk)
>  		return NULL;
>  
>  	if (chunk->qc_num < oinfo->dqi_chunks - 1) {
> 
> base-commit: f443e374ae131c168a065ea1748feac6b2e76613