linux/include
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
..
acpi Merge branches 'acpi-processor', 'acpi-hotplug', 'acpi-init', 'acpi-pm' and 'acpica' 2014-01-29 11:47:18 +01:00
asm-generic Merge branch 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2014-01-27 21:03:39 -08:00
clocksource
crypto
drm Merge tag 'drm-intel-fixes-2014-02-06' of ssh://git.freedesktop.org/git/drm-intel into drm-next 2014-02-11 12:57:27 +10:00
dt-bindings Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2014-01-30 17:07:18 -08:00
keys
kvm
linux f2fs: introduce large directory support 2014-02-27 19:56:09 +09:00
math-emu
media
memory
misc
net net: Move prototype declaration to header file include/net/net_namespace.h from net/ipx/af_ipx.c 2014-02-09 17:32:50 -08:00
pcmcia
ras
rdma IB: Report using RoCE IP based gids in port caps 2014-02-13 14:46:03 -08:00
rxrpc
scsi Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2014-01-31 15:31:23 -08:00
sound ARM: SoC board updates for 3.14 2014-01-23 18:48:28 -08:00
target target: Simplify command completion by removing CMD_T_FAILED flag 2014-02-12 15:14:30 -08:00
trace intel_pstate: Remove energy reporting from pstate_sample tracepoint 2014-02-13 02:11:18 +01:00
uapi Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2014-02-16 11:05:27 -08:00
video video: pxa168fb: Cleanup pxa168fb.h file 2014-01-17 10:57:43 +02:00
xen Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2014-02-14 10:45:18 -08:00
Kbuild