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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
