Commit Graph

62 Commits

Author SHA1 Message Date
Jaegeuk Kim
a4db59ac90 f2fs: expose main_blkaddr in sysfs
Expose in /sys/fs/f2fs/<blockdev>/main_blkaddr the block address where the
main area starts. This allows user mode programs to determine:

- That pinned files that are made exclusively of fully allocated 2MB
  segments will never be unpinned by the file system.

- Where the main area starts. This is required by programs that want to
  verify if a file is made exclusively of 2MB f2fs segments, the alignment
  boundary for segments starts at this address. Testing for 2MB alignment
  relative to the start of the device is incorrect, because for some
  filesystems main_blkaddr is not at a 2MB boundary relative to the start
  of the device.

The entry will be used when validating reliable pinning file feature proposed
by "f2fs: support aligned pinned file".

Signed-off-by: Ramon Pantin <pantin@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2019-11-25 10:01:27 -08:00
Chao Yu
4c3258b9b0 f2fs: fix wrong description in document
As reported in bugzilla, default value of DEF_RAM_THRESHOLD was fixed by
commit 29710bcf94 ("f2fs: fix wrong percentage"), however leaving wrong
description in document, fix it.

https://bugzilla.kernel.org/show_bug.cgi?id=205203

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2019-10-25 09:52:06 -07:00
Chao Yu
d0995b5313 f2fs: add missing documents of reserve_root/resuid/resgid
Add missing documents.

Fixes: 7e65be49ed ("f2fs: add reserved blocks for root user")
Fixes: 7c2e59632b ("f2fs: add resgid and resuid to reserve root blocks")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2019-09-06 16:18:26 -07:00
Daniel Rosenberg
5aba54302a f2fs: include charset encoding information in the superblock
Add charset encoding to f2fs to support casefolding. It is modeled after
the same feature introduced in commit c83ad55eaa ("ext4: include charset
encoding information in the superblock")

Currently this is not compatible with encryption, similar to the current
ext4 imlpementation. This will change in the future.

>From the ext4 patch:
"""
The s_encoding field stores a magic number indicating the encoding
format and version used globally by file and directory names in the
filesystem.  The s_encoding_flags defines policies for using the charset
encoding, like how to handle invalid sequences.  The magic number is
mapped to the exact charset table, but the mapping is specific to ext4.
Since we don't have any commitment to support old encodings, the only
encoding I am supporting right now is utf8-12.1.0.

The current implementation prevents the user from enabling encoding and
per-directory encryption on the same filesystem at the same time.  The
incompatibility between these features lies in how we do efficient
directory searches when we cannot be sure the encryption of the user
provided fname will match the actual hash stored in the disk without
decrypting every directory entry, because of normalization cases.  My
quickest solution is to simply block the concurrent use of these
features for now, and enable it later, once we have a better solution.
"""

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2019-08-23 07:57:13 -07:00
Jaegeuk Kim
cad3836f9e f2fs: allocate blocks for pinned file
This patch allows fallocate to allocate physical blocks for pinned file.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2019-07-02 15:40:42 -07:00
Daniel Rosenberg
4d3aed7090 f2fs: Add option to limit required GC for checkpoint=disable
This extends the checkpoint option to allow checkpoint=disable:%u[%]
This allows you to specify what how much of the disk you are willing
to lose access to while mounting with checkpoint=disable. If the amount
lost would be higher, the mount will return -EAGAIN. This can be given
as a percent of total space, or in blocks.

Currently, we need to run garbage collection until the amount of holes
is smaller than the OVP space. With the new option, f2fs can mark
space as unusable up front instead of requiring garbage collection until
the number of holes is small enough.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2019-06-03 13:27:48 -07:00
Jaegeuk Kim
4d11d13e27 f2fs: add missing sysfs entries in documentation
This patch cleans up documentation to cover missing sysfs entries.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2019-05-30 09:13:41 -07:00
Chao Yu
7321dd97b5 f2fs: fix to document inline_xattr_size option
We missed to add document for inline_xattr_size mount option in f2fs.txt,
add it.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2019-03-05 19:58:05 -08:00
Daniel Rosenberg
4354994f09 f2fs: checkpoint disabling
Note that, it requires "f2fs: return correct errno in f2fs_gc".

This adds a lightweight non-persistent snapshotting scheme to f2fs.

To use, mount with the option checkpoint=disable, and to return to
normal operation, remount with checkpoint=enable. If the filesystem
is shut down before remounting with checkpoint=enable, it will revert
back to its apparent state when it was first mounted with
checkpoint=disable. This is useful for situations where you wish to be
able to roll back the state of the disk in case of some critical
failure.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
[Jaegeuk Kim: use SB_RDONLY instead of MS_RDONLY]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2018-10-16 09:36:39 -07:00
Chao Yu
6f5c2ed0a2 f2fs: split IO error injection according to RW
This patch adds to support injecting error for write IO, this can simulate
IO error like fail_make_request or dm_flakey does.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2018-09-12 13:07:32 -07:00
Chao Yu
d494500a70 f2fs: support fault_type mount option
Previously, once fault injection is on, by default, all kind of faults
will be injected to f2fs, if we want to trigger single or specified
combined type during the test, we need to configure sysfs entry, it will
be a little inconvenient to integrate sysfs configuring into testsuit,
such as xfstest.

So this patch introduces a new mount option 'fault_type' to assist old
option 'fault_injection', with these two mount options, we can specify
any fault rate/type at mount-time.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2018-08-13 10:48:17 -07:00
Jaegeuk Kim
d6290814b0 f2fs: add fsync_mode=nobarrier for non-atomic files
For non-atomic files, this patch adds an option to give nobarrier which
doesn't issue flush commands to the device.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2018-05-29 12:04:08 -07:00
Sheng Yong
ff62af200b f2fs: introduce a new mount option test_dummy_encryption
This patch introduces a new mount option `test_dummy_encryption'
to allow fscrypt to create a fake fscrypt context. This is used
by xfstests.

Signed-off-by: Sheng Yong <shengyong1@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2018-03-17 14:02:57 +09:00
Junling Zheng
93cf93f17c f2fs: introduce mount option for fsync mode
Commit "0a007b97aad6"(f2fs: recover directory operations by fsync)
fixed xfstest generic/342 case, but it also increased the written
data and caused the performance degradation. In most cases, there's
no need to do so heavy fsync actually.

So we introduce new mount option "fsync_mode={posix,strict}" to
control the policy of fsync. "fsync_mode=posix" is set by default,
and means that f2fs uses a light fsync, which follows POSIX semantics.
And "fsync_mode=strict" means that it's a heavy fsync, which behaves
in line with xfs, ext4 and btrfs, where generic/342 will pass, but
the performance will regress.

Signed-off-by: Junling Zheng <zhengjunling@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2018-03-17 13:57:28 +09:00
Jaegeuk Kim
079396270b f2fs: add mount option for segment allocation policy
This patch adds an mount option, "alloc_mode=%s" having two options, "default"
and "reuse".

In "alloc_mode=reuse" case, f2fs starts to allocate segments from 0'th segment
all the time to reassign segments. It'd be useful for small-sized eMMC parts.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2018-03-13 08:05:50 +09:00
Hyunchul Lee
8b3a0ca0fd f2fs: Add the 'whint_mode' mount option to f2fs documentation
Signed-off-by: Hyunchul Lee <cheol.lee@lge.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
[Jaegeuk Kim: Add the write-hint policy in f2fs doc.]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2018-03-13 08:05:37 +09:00
Chao Yu
4b2414d04e f2fs: support journalled quota
This patch supports to enable f2fs to accept quota information through
mount option:
- {usr,grp,prj}jquota=<quota file path>
- jqfmt=<quota type>

Then, in ->mount flow, we can recover quota file during log replaying,
by this, journelled quota can be supported.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
[Jaegeuk Kim: Fix wrong return values.]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2017-08-21 15:54:48 -07:00
Jaegeuk Kim
d9872a698c f2fs: introduce gc_urgent mode for background GC
This patch adds a sysfs entry to control urgent mode for background GC.
If this is set, background GC thread conducts GC with gc_urgent_sleep_time
all the time.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2017-08-15 10:40:12 -07:00
Chao Yu
5c57132eaf f2fs: support project quota
This patch adds to support plain project quota.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2017-07-31 16:48:32 -07:00
Chao Yu
0abd675e97 f2fs: support plain user/group quota
This patch adds to support plain user/group quota.

Change Note by Jaegeuk Kim.

- Use f2fs page cache for quota files in order to consider garbage collection.
  so, quota files are not tolerable for sudden power-cuts, so user needs to do
  quotacheck.

- setattr() calls dquot_transfer which will transfer inode->i_blocks.
  We can't reclaim that during f2fs_evict_inode(). So, we need to count
  node blocks as well in order to match i_blocks with dquot's space.

  Note that, Chao wrote a patch to count inode->i_blocks without inode block.
  (f2fs: don't count inode block in in-memory inode.i_blocks)

- in f2fs_remount, we need to make RW in prior to dquot_resume.

- handle fault_injection case during f2fs_quota_off_umount

- TODO: Project quota

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2017-07-08 23:12:27 -07:00
Chao Yu
56412894b3 f2fs: fix to document fault injection option and sysfs file
Commit 73faec4d99 ("f2fs: add mount option to select fault injection
ratio") and Commit 087968974f ("f2fs: add fault injection to sysfs")
forget to document mount option and sysfs file.

This patch fixes to document them.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2017-07-04 02:11:44 -07:00
Chao Yu
23cf7212a1 f2fs: introduce noinline_xattr mount option
This patch introduces new mount option 'noinline_xattr', so we can disable
inline xattr functionality which is already set as a default mount option.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2017-02-23 10:21:48 -08:00
Tiezhu Yang
6de3f12eb7 f2fs: fix a typo in f2fs.txt
There is a typo "f2f2" in f2fs.txt, this patch fixes it.

Signed-off-by: Tiezhu Yang <kernelpatch@126.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2017-02-23 10:10:49 -08:00
Masanari Iida
04b9a5f0f5 Doc: f2fs: Fix typo in Documentation/filesystems/f2fs.txt
This patch fix a typo in f2fs.txt

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2017-02-22 20:24:50 -08:00
Jaegeuk Kim
ec91538dcc f2fs: get io size bit from mount option
This patch adds to set io_size_bits from mount option.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2017-01-29 12:46:01 +09:00
Chao Yu
97c1794a5d f2fs: enable inline_dentry by default and add noinline_dentry option
Make inline_dentry as default mount option to improve space usage and
IO performance in scenario of numerous small directory.
It adds noinline_dentry mount option, instead.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2016-08-29 18:31:17 -07:00
Chao Yu
64058be9c8 f2fs: add nodiscard mount option
This patch adds 'nodiscard' mount option.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2016-07-08 10:33:26 -07:00
Jaegeuk Kim
36abef4e79 f2fs: introduce mode=lfs mount option
This mount option is to enable original log-structured filesystem forcefully.
So, there should be no random writes for main area.

Especially, this supports host-managed SMR device.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2016-06-13 11:55:21 -07:00
Chao Yu
343f40f0a7 f2fs: introduce new option for controlling data flush
Add a new option 'data_flush' to enable data flush functionality.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2015-12-16 09:25:48 -08:00
Masanari Iida
4bb9998d38 Doc: f2fs: Fix typos in Documentation/filesystems/f2fs.txt
This patch fix some typos in Documentation/filesystems/f2fs.txt

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2015-12-04 11:52:33 -08:00
Jaegeuk Kim
6aefd93b01 f2fs: introduce background_gc=sync mount option
This patch introduce background_gc=sync enabling synchronous cleaning in
background.

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2015-10-09 16:20:57 -07:00
Jaegeuk Kim
7daaea256d f2fs: add noextent_cache mount option
This patch adds noextent_cache mount option.

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2015-08-04 14:09:55 -07:00
Wanpeng Li
7534279798 f2fs: enable inline data by default
Enable inline_data feature by default since it brings us better
performance and space utilization and now has already stable.
Add another option noinline_data to disable it during mount.

Suggested-by: Jaegeuk Kim <jaegeuk@kernel.org>
Suggested-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2015-04-10 15:08:52 -07:00
Chao Yu
8967215954 f2fs: add a mount option for rb-tree extent cache
This patch adds a mount option 'extent_cache' in f2fs.

It is try to use a rb-tree based extent cache to cache more mapping information
with less memory if this option is set, otherwise we will use the original one
extent info cache.

Suggested-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2015-03-03 09:58:46 -08:00
Jaegeuk Kim
bba681cbb2 f2fs: introduce a batched trim
This patch introduces a batched trimming feature, which submits split discard
commands.

This is to avoid long latency due to huge trim commands.
If fstrim was triggered ranging from 0 to the end of device, we should lock
all the checkpoint-related mutexes, resulting in very long latency.

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2015-02-11 17:04:44 -08:00
Jaegeuk Kim
2d834bf9ac f2fs: support norecovery mount option
This patch adds a mount option, norecovery, which is mostly same as
disable_roll_forward. The only difference is that norecovery should be activated
with read-only mount option.

This can be used when user wants to check whether f2fs is mountable or not
without any recovery process. (e.g., xfstests/200)

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2015-02-11 17:04:40 -08:00
Jaegeuk Kim
d5053a34a9 f2fs: introduce -o fastboot for reducing booting time only
If a system wants to reduce the booting time as a top priority, now we can
use a mount option, -o fastboot.
With this option, f2fs conducts a little bit slow write_checkpoint, but
it can avoid the node page reads during the next mount time.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2014-11-04 17:34:15 -08:00
Chao Yu
d37a868ffc f2fs: update f2fs documentation for inline dir support
This patch adds descriptions for the inline dir support in f2fs document.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2014-11-03 16:07:32 -08:00
Jaegeuk Kim
9b5f136fd4 f2fs: change the ipu_policy option to enable combinations
This patch changes the ipu_policy setting to use any combination of orthogonal policies.

Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2014-09-23 11:10:24 -07:00
Jaegeuk Kim
c1ce1b02bb f2fs: give an option to enable in-place-updates during fsync to users
If user wrote F2FS_IPU_FSYNC:4 in /sys/fs/f2fs/ipu_policy, f2fs_sync_file
only starts to try in-place-updates.
And, if the number of dirty pages is over /sys/fs/f2fs/min_fsync_blocks, it
keeps out-of-order manner. Otherwise, it triggers in-place-updates.

This may be used by storage showing very high random write performance.

For example, it can be used when,

Seq. writes (Data) + wait + Seq. writes (Node)

is pretty much slower than,

Rand. writes (Data)

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2014-09-16 04:10:44 -07:00
Jaegeuk Kim
0f7b2abd18 f2fs: add nobarrier mount option
This patch adds a mount option, nobarrier, in f2fs.
The assumption in here is that file system keeps the IO ordering, but
doesn't care about cache flushes inside the storages.

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2014-07-29 05:27:48 -07:00
Chao Yu
bfec07d0f8 f2fs: avoid overflow when large directory feathure is enabled
When large directory feathure is enable, We have one case which could cause
overflow in dir_buckets() as following:
special case: level + dir_level >= 32 and level < MAX_DIR_HASH_DEPTH / 2.

Here we define MAX_DIR_BUCKETS to limit the return value when the condition
could trigger potential overflow.

Changes from V1
 o modify description of calculation in f2fs.txt suggested by Changman Lee.

Suggested-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2014-06-04 13:34:30 +09:00
Jaegeuk Kim
6b4afdd794 f2fs: introduce f2fs_issue_flush to avoid redundant flush issue
Some storage devices show relatively high latencies to complete cache_flush
commands, even though their normal IO speed is prettry much high. In such
the case, it needs to merge cache_flush commands as much as possible to avoid
issuing them redundantly.
So, this patch introduces a mount option, "-o flush_merge", to mitigate such
the overhead.

If this option is enabled by user, F2FS merges the cache_flush commands and then
issues just one cache_flush on behalf of them. Once the single command is
finished, F2FS sends a completion signal to all the pending threads.

Note that, this option can be used under a workload consisting of very intensive
concurrent fsync calls, while the storage handles cache_flush commands slowly.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-04-07 09:50:58 +09:00
Jaegeuk Kim
58c410351e f2fs: change reclaim rate in percentage
It is more reasonable to determine the reclaiming rate of prefree segments
according to the volume size, which is set to 5% by default.
For example, if the volume is 128GB, the prefree segments are reclaimed
when the number reaches to 6.4GB.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-03-20 22:10:10 +09:00
Jaegeuk Kim
cdfc41c134 f2fs: throttle the memory footprint with a sysfs entry
This patch introduces ram_thresh, a sysfs entry, which controls the memory
footprint used by the free nid list and the nat cache.

Previously, the free nid list was controlled by MAX_FREE_NIDS, while the nat
cache was managed by NM_WOUT_THRESHOLD.
However, this approach cannot be applied dynamically according to the system.

So, this patch adds ram_thresh that users can specify the threshold, which is
in order of 1 / 1024.
For example, if the total ram size is 4GB and the value is set to 10 by default,
f2fs tries to control the number of free nids and nat caches not to consume over
10 * (4GB / 1024) = 10MB.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-03-20 22:10:09 +09:00
Jaegeuk Kim
ab9fa662e4 f2fs: add an sysfs entry to control the directory level
This patch adds an sysfs entry to control dir_level used by the large directory.

The description of this entry is:

 dir_level                    This parameter controls the directory level to
			      support large directory. If a directory has a
			      number of files, it can reduce the file lookup
			      latency by increasing this dir_level value.
			      Otherwise, it needs to decrease this value to
			      reduce the space overhead. The default value is 0.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-02-27 20:31:15 +09:00
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
Jaegeuk Kim
3bac380c90 f2fs: update documents and a MAINTAINERS entry
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>
2014-01-09 21:00:06 +09:00
Huajun Li
e4024e86c2 f2fs: update f2fs Documentation
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>
2013-12-26 20:40:44 +09:00
Jaegeuk Kim
ba0697ec98 f2fs: add description about small_discards in document
This patch adds a description about small_disacrds in the f2fs document.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23 10:18:07 +09:00