linux/Documentation/filesystems
Jaegeuk Kim 3843154598 f2fs: introduce large directory support
This patch introduces an i_dir_level field to support large directory.

Previously, f2fs maintains multi-level hash tables to find a dentry quickly
from a bunch of chiild dentries in a directory, and the hash tables consist of
the following tree structure as below.

In Documentation/filesystems/f2fs.txt,

----------------------
A : bucket
B : block
N : MAX_DIR_HASH_DEPTH
----------------------

level #0   | A(2B)
           |
level #1   | A(2B) - A(2B)
           |
level #2   | A(2B) - A(2B) - A(2B) - A(2B)
     .     |   .       .       .       .
level #N/2 | A(2B) - A(2B) - A(2B) - A(2B) - A(2B) - ... - A(2B)
     .     |   .       .       .       .
level #N   | A(4B) - A(4B) - A(4B) - A(4B) - A(4B) - ... - A(4B)

But, if we can guess that a directory will handle a number of child files,
we don't need to traverse the tree from level #0 to #N all the time.
Since the lower level tables contain relatively small number of dentries,
the miss ratio of the target dentry is likely to be high.

In order to avoid that, we can configure the hash tables sparsely from level #0
like this.

level #0   | A(2B) - A(2B) - A(2B) - A(2B)

level #1   | A(2B) - A(2B) - A(2B) - A(2B) - A(2B) - ... - A(2B)
     .     |   .       .       .       .
level #N/2 | A(2B) - A(2B) - A(2B) - A(2B) - A(2B) - ... - A(2B)
     .     |   .       .       .       .
level #N   | A(4B) - A(4B) - A(4B) - A(4B) - A(4B) - ... - A(4B)

With this structure, we can skip the ineffective tree searches in lower level
hash tables.

This patch adds just a facility for this by introducing i_dir_level in
f2fs_inode.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-02-27 19:56:09 +09:00
..
caching FS-Cache: Provide the ability to enable/disable cookies 2013-09-27 18:40:25 +01:00
cifs cifs: update cifs.txt and remove some outdated infos 2013-09-13 16:29:58 -05:00
configfs
nfs Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
pohmelfs
9p.txt 9p: update documentation 2014-01-24 10:55:21 -06:00
00-INDEX Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
adfs.txt
affs.txt
afs.txt
autofs4-mount-control.txt
automount-support.txt
befs.txt
bfs.txt
btrfs.txt btrfs: Add treelog mount option. 2014-01-28 13:20:20 -08:00
ceph.txt
coda.txt
cramfs.txt
debugfs.txt debugfs: more tightly restrict default mount mode 2012-08-27 13:42:02 -07:00
devpts.txt
directory-locking vfs: take i_mutex on renamed file 2013-11-09 00:16:40 -05:00
dlmfs.txt
dnotify_test.c
dnotify.txt
ecryptfs.txt
efivarfs.txt efivarfs: Add documentation for the EFI variable filesystem 2012-10-30 10:39:18 +00:00
exofs.txt
ext2.txt
ext3.txt ext3: allow specifying external journal by pathname mount option 2013-07-31 22:11:15 +02:00
ext4.txt Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-09-06 09:36:28 -07:00
f2fs.txt f2fs: introduce large directory support 2014-02-27 19:56:09 +09:00
fiemap.txt
files.txt
fuse.txt
gfs2-glocks.txt GFS2: Update glock doc to add new stats info 2012-05-10 12:41:40 +01:00
gfs2-uevents.txt
gfs2.txt GFS2: Update main gfs2 doc 2012-05-10 11:45:31 +01:00
hfs.txt
hfsplus.txt
hpfs.txt
inotify.txt
isofs.txt
jfs.txt doc: fix misspellings with 'codespell' tool 2013-05-28 12:02:12 +02:00
Locking doc: Fix typo (acces_process_vm -> access_process_vm) 2013-12-19 15:12:21 +01:00
locks.txt
logfs.txt
Makefile
mandatory-locking.txt
ncpfs.txt
nilfs2.txt nilfs2: add comments for ioctls 2014-01-23 16:37:00 -08:00
ntfs.txt
ocfs2.txt
omfs.txt
path-lookup.txt
porting iget/iget5: don't bother with ->i_lock until we find a match 2013-11-09 00:16:31 -05:00
proc.txt mm, oom: base root bonus on current usage 2014-01-30 16:56:56 -08:00
qnx6.txt doc: filesystems : Fix typo in Documentations/filesystems 2013-08-20 13:45:56 +02:00
quota.txt
ramfs-rootfs-initramfs.txt initmpfs: use initramfs if rootfstype= or root= specified 2013-09-11 15:59:38 -07:00
relay.txt doc: Fix typo in doucmentations 2013-07-25 12:34:15 +02:00
romfs.txt
seq_file.txt
sharedsubtree.txt
spufs.txt
squashfs.txt
sysfs-pci.txt
sysfs-tagging.txt doc: Fix typo in doucmentations 2013-07-25 12:34:15 +02:00
sysfs.txt Documentation/filesystems/sysfs.txt: fix device_attribute declaration 2014-01-23 16:37:00 -08:00
sysv-fs.txt
tmpfs.txt
ubifs.txt
udf.txt
ufs.txt
vfat.txt Documentation/filesystems/vfat.txt: fix directory entry example 2013-11-13 12:09:32 +09:00
vfs.txt Documentation/filesystems/vfs.txt: update file_operations documentation 2014-01-30 16:56:56 -08:00
xfs-delayed-logging-design.txt
xfs-self-describing-metadata.txt xfs: add metadata CRC documentation 2013-04-27 13:27:43 -05:00
xfs.txt doc: filesystems : Fix typo in Documentations/filesystems 2013-08-20 13:45:56 +02:00
xip.txt