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Message-ID: <2abb3c694107764dea1e118566eb3c6c331404fc.camel@perches.com>
Subject: Re: [PATCH 4/5] mm: shmem: Convert shmem_enabled_show to use
 sysfs_emit_at
From:   Joe Perches <joe@perches.com>
To:     Matthew Wilcox <willy@infradead.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Hugh Dickins <hughd@google.com>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Date:   Sun, 01 Nov 2020 14:13:52 -0800
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On Sun, 2020-11-01 at 22:06 +0000, Matthew Wilcox wrote:
> Oh, ugh, sysfs_emit() should be able to work on a buffer that isn't
> page aligned.  Greg, how about this?
> 
> +++ b/fs/sysfs/file.c
> @@ -722,13 +722,13 @@ int sysfs_emit(char *buf, const char *fmt, ...)
>  {
>         va_list args;
>         int len;
> +       int start = offset_in_page(buf);

I thought of that originally and didn't want to implement it that
way as it allows sysfs_emit to be used on non-page aligned buffers.

Using two functions makes sure the buf is always page aligned and
so buf should never defectively be passed in unaligned.