linux.git/fs/f2fs/segment.c, branch v4.1

f2fs: add some tracepoints to debug volatile and atomic writes

2015-04-10T22:08:47+00:00

Signed-off-by: Jaegeuk Kim

f2fs: fix to cover sentry_lock for block allocation

2015-04-10T22:08:43+00:00

In the following call stack, f2fs changes the bitmap for dirty segments and # of
dirty sentries without grabbing sit_i->sentry_lock.
This can result in mismatch on bitmap and # of dirty sentries, since if there
are some direct_io operations.

In allocate_data_block,
 - __allocate_new_segments
  - mutex_lock(&curseg->curseg_mutex);
  - s_ops->allocate_segment
   - new_curseg/change_curseg
    - reset_curseg
     - __set_sit_entry_type
      - __mark_sit_entry_dirty
       - set_bit(dirty_sentries_bitmap)
       - dirty_sentries++;

Signed-off-by: Jaegeuk Kim

f2fs: fix to issue small discard in real-time mode discard

2015-04-10T22:08:31+00:00

Now in f2fs, we share functions and structures for batch mode and real-time mode
discard. For real-time mode discard, in shared function add_discard_addrs, we
will use uninitialized trim_minlen in struct cp_control to compare with length
of contiguous free blocks to decide whether skipping discard fragmented freespace
or not, this makes us ignore small discard sometimes. Fix it.

Signed-off-by: Chao Yu 
Reviewed-by : Changman Lee 
Signed-off-by: Jaegeuk Kim

f2fs: don't need to collect dirty sit entries and flush journal when there's no dirty sit entries

2015-04-10T22:08:29+00:00

 Don't need to collect dirty sit entries and flush sit journal to sit
 entries when there's no dirty sit entries. This patch check dirty_sentries
 earlier just like flush_nat_entries.

Signed-off-by: Wanpeng Li 
Reviewed-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: enable rb-tree extent cache

2015-03-03T17:58:47+00:00

This patch enables rb-tree based extent cache in f2fs.

When we mount with "-o extent_cache", f2fs will try to add recently accessed
page-block mappings into rb-tree based extent cache as much as possible, instead
of original one extent info cache.

By this way, f2fs can support more effective cache between dnode page cache and
disk. It will supply high hit ratio in the cache with fewer memory when dnode
page cache are reclaimed in environment of low memory.

Storage: Sandisk sd card 64g
1.append write file (offset: 0, size: 128M);
2.override write file (offset: 2M, size: 1M);
3.override write file (offset: 4M, size: 1M);
...
4.override write file (offset: 48M, size: 1M);
...
5.override write file (offset: 112M, size: 1M);
6.sync
7.echo 3 > /proc/sys/vm/drop_caches
8.read file (size:128M, unit: 4k, count: 32768)
(time dd if=/mnt/f2fs/128m bs=4k count=32768)

Extent Hit Ratio:
		before		patched
Hit Ratio	121 / 1071	1071 / 1071

Performance:
		before		patched
real    	0m37.051s	0m35.556s
user    	0m0.040s	0m0.026s
sys     	0m2.990s	0m2.251s

Memory Cost:
		before		patched
Tree Count:	0		1 (size: 24 bytes)
Node Count:	0		45 (size: 1440 bytes)

v3:
 o retest and given more details of test result.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: use spinlock for segmap_lock instead of rwlock

2015-02-12T01:04:51+00:00

rwlock can provide better concurrency when there are much more readers than
writers because readers can hold the rwlock simultaneously.

But now, for segmap_lock rwlock in struct free_segmap_info, there is only one
reader 'mount' from below call path:
->f2fs_fill_super
  ->build_segment_manager
    ->build_dirty_segmap
      ->init_dirty_segmap
        ->find_next_inuse
          read_lock
          ...
          read_unlock

Now that our concurrency can not be improved since there is no other reader for
this lock, we do not need to use rwlock_t type for segmap_lock, let's replace it
with spinlock_t type.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: avoid variable length array

2015-02-12T01:04:50+00:00

Instead of using variable length array, this patch let preallocate memory for
them.

Signed-off-by: Jaegeuk Kim

f2fs: introduce macros to convert bytes and blocks in f2fs

2015-02-12T01:04:48+00:00

This patch adds two macros for transition between byte and block offsets.
Currently, f2fs only supports 4KB blocks, so use the default size for now.

Signed-off-by: Jaegeuk Kim

f2fs: introduce a batched trim

2015-02-12T01:04:44+00:00

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 
Signed-off-by: Jaegeuk Kim

f2fs: split UMOUNT and FASTBOOT flags

2015-02-12T01:04:41+00:00

This patch adds FASTBOOT flag into checkpoint as follows.

 - CP_UMOUNT_FLAG is set when system is umounted.
 - CP_FASTBOOT_FLAG is set when intermediate checkpoint having node summaries
   was done.

So, if you get CP_UMOUNT_FLAG from checkpoint, the system was umounted cleanly.
Instead, if there was sudden-power-off, you can get CP_FASTBOOT_FLAG or nothing.

Reviewed-by: Chao Yu 
Signed-off-by: Jaegeuk Kim