From mboxrd@z Thu Jan  1 00:00:00 1970
From: NeilBrown <neilb@suse.com>
Subject: Re: [PATCH v6 06/11] md/r5cache: sysfs entry r5c_journal_mode
Date: Thu, 17 Nov 2016 11:29:10 +1100
Message-ID: <87y40j7xux.fsf@notabene.neil.brown.name>
References: <20161110204623.3484694-1-songliubraving@fb.com> <20161110204623.3484694-7-songliubraving@fb.com>
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Cc: shli@fb.com, kernel-team@fb.com, dan.j.williams@intel.com, hch@infradead.org, liuzhengyuang521@gmail.com, liuzhengyuan@kylinos.cn, Song Liu <songliubraving@fb.com>
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On Fri, Nov 11 2016, Song Liu wrote:

> +static ssize_t r5c_journal_mode_store(struct mddev *mddev,
> +				      const char *page, size_t len)
> +{
> +	struct r5conf *conf = mddev->private;
> +	struct r5l_log *log = conf->log;
> +	int val = -1, i;
> +
> +	if (!log)
> +		return -ENODEV;
> +
> +	for (i = 0; i < sizeof(r5c_journal_mode_str) / sizeof(r5c_journal_mode_str[0]); i++)
> +		if (strlen(r5c_journal_mode_str[i]) == len - 1 &&
> +		    strncmp(page, r5c_journal_mode_str[i], len - 1) == 0) {
> +			val = i;
> +			break;

I don't really like this "len - 1".
It is presumably there to skip a trailing newline, but it doesn't check
that there is a new line to skip.
Some people seem to have a habit of using "echo -n ...." to write to
sysfs.
I suggest.

 if (len && page[len-1] == '\n')
       len -= 1;

then just use "len" instead of "len - 1".


Thanks,
NeilBrown

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