From: "Sungjong Seo" <sj1557.seo@samsung.com>
To: "'Hyeongseok Kim'" <hyeongseok@gmail.com>, <namjae.jeon@samsung.com>
Cc: <linux-kernel@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>,
<sj1557.seo@samsung.com>
Subject: RE: [PATCH] exfat: speed up iterate/lookup by fixing start point of traversing fat chain
Date: Thu, 18 Mar 2021 01:07:21 +0900 [thread overview]
Message-ID: <a64901d71b47$9cacb070$d6061150$@samsung.com> (raw)
In-Reply-To: <20210315043316.54508-1-hyeongseok@gmail.com>
> When directory iterate and lookup is called, there is a buggy rewinding of
> start point for traversing fat chain to the directory entry's first
> cluster. This caused repeated fat chain traversing from the first entry of
> the directory that would show worse performance if huge amounts of files
> exist under single directory.
> Fix not to rewind, make continue from currently referenced cluster and dir
> entry.
>
> Tested with 50,000 files under single directory / 256GB sdcard, with
> command "time ls -l > /dev/null",
> Before : 0m08.69s real 0m00.27s user 0m05.91s system
> After : 0m07.01s real 0m00.25s user 0m04.34s system
>
> Signed-off-by: Hyeongseok Kim <hyeongseok@gmail.com>
> ---
> fs/exfat/dir.c | 42 +++++++++++++++++++++++++++++++++---------
> 1 file changed, 33 insertions(+), 9 deletions(-)
>
> diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c index
> e1d5536de948..59d12eaa0649 100644
> --- a/fs/exfat/dir.c
> +++ b/fs/exfat/dir.c
> @@ -147,7 +147,7 @@ static int exfat_readdir(struct inode *inode, loff_t
> *cpos, struct exfat_dir_ent
> 0);
>
> *uni_name.name = 0x0;
> - exfat_get_uniname_from_ext_entry(sb, &dir, dentry,
> + exfat_get_uniname_from_ext_entry(sb, &clu, i,
> uni_name.name);
Looks good. Old code looks like a bug as you said.
> exfat_utf16_to_nls(sb, &uni_name,
> dir_entry->namebuf.lfn,
> @@ -911,10 +911,15 @@ enum {
> };
>
> /*
> - * return values:
> - * >= 0 : return dir entiry position with the name in dir
> - * -ENOENT : entry with the name does not exist
> - * -EIO : I/O error
> + * @ei: inode info of directory
> + * @p_dir: input as directory structure in which we search name
> + * if found, output as a cluster dir where the name exists
> + * if not found, not changed from input
> + * @num_entries entry size of p_uniname
> + * @return:
> + * >= 0: dir entry position from output p_dir.dir
> + * -ENOENT: entry with the name does not exist
> + * -EIO: I/O error
> */
> int exfat_find_dir_entry(struct super_block *sb, struct exfat_inode_info
> *ei,
> struct exfat_chain *p_dir, struct exfat_uni_name *p_uniname,
> @@ -925,14 +930,16 @@ int exfat_find_dir_entry(struct super_block *sb,
> struct exfat_inode_info *ei,
[snip]
hint_stat->clu = p_dir->dir;
> hint_stat->eidx = 0;
> - return (dentry - num_ext);
> +
> + exfat_chain_dup(p_dir, &tmp_clu);
> + return dentry_in_cluster;
> }
> }
>
> hint_stat->clu = clu.dir;
> hint_stat->eidx = dentry + 1;
> - return dentry - num_ext;
> +
> + exfat_chain_dup(p_dir, &tmp_clu);
> + return dentry_in_cluster;
> }
Changing the functionality of exfat find_dir_entry() will affect
exfat_find() and exfat_lookup(), breaking the concept of ei->dir.dir
which should have the starting cluster of its parent directory.
Well, is there any missing patch related to exfat_find()?
It would be nice to modify the caller of this function, exfat_find(),
so that this change in functionality doesn't affect other functions.
Thanks.
>
> int exfat_count_ext_entries(struct super_block *sb, struct exfat_chain
> *p_dir,
> --
> 2.27.0.83.g0313f36
next prev parent reply other threads:[~2021-03-17 16:08 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20210315043335epcas1p2bf257806e9ba1c2a492739a6424a2b44@epcas1p2.samsung.com>
2021-03-15 4:33 ` [PATCH] exfat: speed up iterate/lookup by fixing start point of traversing fat chain Hyeongseok Kim
2021-03-17 16:07 ` Sungjong Seo [this message]
2021-03-18 1:02 ` Hyeongseok Kim
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='a64901d71b47$9cacb070$d6061150$@samsung.com' \
--to=sj1557.seo@samsung.com \
--cc=hyeongseok@gmail.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=namjae.jeon@samsung.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).