linux-kernel - [f2fs-dev][PATCH 0/5] f2fs: support inline dir

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Message-id: <00be01cfb37b$f3ba83f0$db2f8bd0$@samsung.com>
Date:	Sat, 09 Aug 2014 10:44:31 +0800
From:	Chao Yu <chao2.yu@...sung.com>
To:	Jaegeuk Kim <jaegeuk@...nel.org>,
	Changman Lee <cm224.lee@...sung.com>
Cc:	linux-f2fs-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org
Subject: [f2fs-dev][PATCH 0/5] f2fs: support inline dir

There are large space in f2fs inode, so last inline data patch set have made
f2fs to acquire the ability of storing data of small file (less than ~3.4k)
directly in inode block, but not support inline dir. In this patch, we make
f2fs to support inline dir.

Layout:
Inline dir layout is the same as inline data layout,
a. i_addr[0] are reserved space for converting from inline dir to regular one
when out-of-space occur in inline dentry.
b. i_addr[1..872] will be used as storing space of inline dentry.
c. i_addr[873..922] are reserved for inline xattr.

Size:
Since our max size of inline dir space is limit to MAX_INLINE_DATA (3488 bytes), 
we introduce inline dentry struct fit for available space, then our dentry slot
number in inline dentry reduce to 182, less than normal dentry block's 214.

Process:
In inline dir mode, our dir entries will be lookuped/stored/deleted in the
inline dentry space of inode, util there are no more space to store new added
dir entry, in this case we will convert inline dentry to normal 0-index dentry
block and disable inline dir mode for this inode.

Benefit points:
a) space saving
   1) Test with fsstress with special arguments, it can save about 3% space.
   time fsstress -c -p 20 -n 500 -l 10 -d /mnt/f2fs -w -f chown=0 -f creat=10
   -f dwrite=0 -f fdatasync=0 -f fsync=0 -f link=10 -f mkdir=10 -f mknod=10
   -f rename=0 -f rmdir=0 -f symlink=10 -f truncate=0 -f unlink=0 -f write=10 -S
   based	/dev/sdb        20969472  2234136  18591976  11% /mnt/f2fs
   patched	/dev/sdb        20969472  2303120  18522992  12% /mnt/f2fs
   2) Test with storing kernel src, it can save less than 1% space.

b) performance
   Test with fsstress shows cost time reduce 21%.
   time fsstress -d /mnt/f2fs -l 5 -n 1000 -p 20 -c -r
   based	168.503 s  (inline data)
   patched	132.840 s  (inline data + inline dir)

Chao Yu (5):
  f2fs: add infra macro and sturct for inline dir
  f2fs: export dir operations for inline dir
  f2fs: add key function to handle inline dir
  f2fs: enable inline dir handling
  f2fs: update f2fs documentation

 Documentation/filesystems/f2fs.txt |   5 +-
 fs/f2fs/dir.c                      |  48 +++--
 fs/f2fs/f2fs.h                     |  18 +-
 fs/f2fs/inline.c                   | 388 +++++++++++++++++++++++++++++++++++++
 fs/f2fs/namei.c                    |   8 +-
 fs/f2fs/recovery.c                 |   2 +-
 include/linux/f2fs_fs.h            |  18 ++
 7 files changed, 469 insertions(+), 18 deletions(-)

-- 
2.0.1.474.g72c7794

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