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 7% 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
Dev 1K-blocks Used Available Use% Mounted on
empty /dev/sdb 20969472 1134600 19691512 6% /mnt/f2fs
based /dev/sdb 20969472 2331676 18494436 12% /mnt/f2fs
patched /dev/sdb 20969472 2247480 18578632 11% /mnt/f2fs
2) Test with storing kernel src, it can save less than 1.4% space.
empty /dev/sdb 20969472 1134600 19691512 6% /mnt/f2fs
based /dev/sdb 20969472 1934656 18891456 10% /mnt/f2fs
patched /dev/sdb 20969472 1923400 18902712 10% /mnt/f2fs
b) performance
Test with fsstress shows cost time reduce about 5%.
time fsstress -d /mnt/f2fs -l 5 -n 1000 -p 20 -c -r
based 135.652 s
patched 129.256 s (mount -o inline_dentry)
v2:
o introduce f2fs_drop_nlink from f2fs_delete_entry to reuse code in
f2fs_delete_inline_entry.
o remove kmap/kunmap for inode page pointed out by Jaegeuk Kim.
o introduce a new mount option inline_dentry for inline dir pointed out by
Jaegeuk Kim.
o rebase to last dev of f2fs (20140924).
o retest performance/space-gain for inline dir excluding influence of inline
data.
Chao Yu (6):
f2fs: add infra struct and helper for inline dir
f2fs: add a new mount option 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 for inline dir support
Documentation/filesystems/f2fs.txt | 4 +
fs/f2fs/dir.c | 103 +++++++----
fs/f2fs/f2fs.h | 40 ++++-
fs/f2fs/file.c | 2 +-
fs/f2fs/inline.c | 347 +++++++++++++++++++++++++++++++++++++
fs/f2fs/namei.c | 38 ++--
fs/f2fs/recovery.c | 5 +-
fs/f2fs/super.c | 7 +
include/linux/f2fs_fs.h | 19 ++
9 files changed, 512 insertions(+), 53 deletions(-)
--
2.0.1.474.g72c7794
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