RE: [PATCH v3] exfat: speed up iterate/lookup by fixing start point of traversing cluster chain

["Sungjong Seo" <sj1557.seo@samsung.com>]

> When directory iterate and lookup is called, there's a buggy rewinding of
> start point for traversing cluster chain to the parent directory entry's
> first cluster. This caused repeated cluster chain traversing from the
> first entry of the parent directory that would show worse performance if
> huge amounts of files exist under the parent 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>

Looks good.
Thanks for your contribution.

Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>

> ---
>  fs/exfat/dir.c      | 19 +++++++++++++------
>  fs/exfat/exfat_fs.h |  2 +-
>  fs/exfat/namei.c    |  9 ++++++++-
>  3 files changed, 22 insertions(+), 8 deletions(-)