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>
This patch adds missing some description of sysfs entries in
- Documentation/ABI/testing/sysfs-fs-f2fs
- Documentation/filesystems/f2fs.txt.
And it adds a maintained document entry of F2FS in MAINTAINERS.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch describes the inline_data support in f2fs document.
Signed-off-by: Huajun Li <huajun.li@intel.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch introduces new sysfs entries for users to control the policy of
in-place-updates, namely IPU, in f2fs.
Sometimes f2fs suffers from performance degradation due to its out-of-place
update policy that produces many additional node block writes.
If the storage performance is very dependant on the amount of data writes
instead of IO patterns, we'd better drop this out-of-place update policy.
This patch suggests 5 polcies and their triggering conditions as follows.
[sysfs entry name = ipu_policy]
0: F2FS_IPU_FORCE all the time,
1: F2FS_IPU_SSR if SSR mode is activated,
2: F2FS_IPU_UTIL if FS utilization is over threashold,
3: F2FS_IPU_SSR_UTIL if SSR mode is activated and FS utilization is over
threashold,
4: F2FS_IPU_DISABLE disable IPU. (=default option)
[sysfs entry name = min_ipu_util]
This parameter controls the threshold to trigger in-place-updates.
The number indicates percentage of the filesystem utilization, and used by
F2FS_IPU_UTIL and F2FS_IPU_SSR_UTIL policies.
For more details, see need_inplace_update() in segment.h.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch adds a control method in sysfs to reclaim prefree segments.
Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Add sysfs entry gc_idle to control the gc policy. Where
gc_idle = 1 corresponds to selecting a cost benefit approach,
while gc_idle = 2 corresponds to selecting a greedy approach
to garbage collection. The selection is mutually exclusive one
approach will work at any point. If gc_idle = 0, then this
option is disabled.
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Reviewed-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
[Jaegeuk Kim: change the select_gc_type() flow slightly]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Add sysfs entries to control the timing parameters for
f2fs gc thread.
Various Sysfs options introduced are:
gc_min_sleep_time: Min Sleep time for GC in ms
gc_max_sleep_time: Max Sleep time for GC in ms
gc_no_gc_sleep_time: Default Sleep time for GC in ms
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Reviewed-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
[Jaegeuk Kim: fix an umount bug and some minor changes]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch adds some description on fsck.f2fs and dump.f2fs which is
recently merged into f2fs-tools.
Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Add the f2fs_remount function call which will be used
during the filesystem remounting. This function
will help us to change the mount options specific to
f2fs.
Also modify the f2fs background_gc mount option, which
will allow the user to dynamically trun on/off the
garbage collection in f2fs based on the background_gc
value. If background_gc=on, Garbage collection will
be turned off & if background_gc=off, Garbage collection
will be truned on.
By default the garbage collection is on in f2fs.
Change Log:
v2: Incorporated the review comments by Gu Zheng.
Removing the restore part for VFS flags
Updating comments with proper flag conditions
Display GC background option as ON/OFF
Revised conditions to stop GC in case of remount
v1: Initial changes for adding remount_fs callback
support.
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Reviewed-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
[Jaegeuk Kim: change /** with /* for the coding style]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
o mkfs.f2fs supports no discard option.
o fixed volume label size in 512 bytes.
Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
document to reflect the layout generated by mkfs.f2fs .
Signed-off-by: Huajun Li <huajun.li.lee@gmail.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
In f2fs_fs.h, one f2fs inode contains 923 data block pointers, while
f2fs documentation says it is 929. Fix this inconsistence.
Signed-off-by: Huajun Li <huajun.li.lee@gmail.com>
I moved the f2fs-tools.git into kernel.org.
And I added a new mailing list, linux-f2fs-devel@lists.sourceforge.net.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This adds a document describing the mount options, proc entries, usage, and
design of Flash-Friendly File System, namely F2FS.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
