linux-kernel - Re: [PATCH] fat: eliminate iterations in fat_search

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Message-ID: <87vcasxgre.fsf@devron.myhome.or.jp>
Date:	Sun, 20 Jan 2013 19:58:45 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	akpm@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Namjae Jeon <namjae.jeon@...sung.com>,
	Ravishankar N <ravi.n1@...sung.com>
Subject: Re: [PATCH] fat: eliminate iterations in fat_search_long in case of EOD

Namjae Jeon <linkinjeon@...il.com> writes:

> From: Namjae Jeon <namjae.jeon@...sung.com>
>
> When searching a directory for names, we can stop checking for further
> entries if we detect End of Directory, i.e. if (de->name[0] == 0x00).The
> current code traverses the cluster chain of a directory until a hit is
> found or till the last cluster for that directory, ignoring the EOD mark.
> Fix this.

f_pos still works fine after this change?

> Signed-off-by: Namjae Jeon <namjae.jeon@...sung.com>
> Signed-off-by: Ravishankar N <ravi.n1@...sung.com>
> ---
>  fs/fat/dir.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/fat/dir.c b/fs/fat/dir.c
> index 58bf744..cde0e69 100644
> --- a/fs/fat/dir.c
> +++ b/fs/fat/dir.c
> @@ -484,10 +484,10 @@ parse_record:
>  		nr_slots = 0;
>  		if (de->name[0] == DELETED_FLAG)
>  			continue;
> +		if (!de->name[0])
> +			goto end_of_dir;
>  		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
>  			continue;
> -		if (de->attr != ATTR_EXT && IS_FREE(de->name))
> -			continue;
>  		if (de->attr == ATTR_EXT) {
>  			int status = fat_parse_long(inode, &cpos, &bh, &de,
>  						    &unicode, &nr_slots);

-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
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