linux-toradex.git/fs/f2fs/segment.h, branch v4.1.21

f2fs: reduce searching region of segmap when set free section

2015-04-10T22:08:36+00:00

In __set_free we will check whether all segment are free in one section
when free one segment, in order to set section to free status. But the
searching region of segmap is from start segno to last segno of main
area, it's not necessary. So let's just only check all segment bitmap
of target section.

Signed-off-by: Wanpeng Li 
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: merge flags in struct f2fs_sb_info

2015-02-12T01:04:38+00:00

Currently, there are several variables with Boolean type as below:

struct f2fs_sb_info {
...
	int s_dirty;
	bool need_fsck;
	bool s_closing;
...
	bool por_doing;
...
}

For this there are some issues:
1. there are some space of f2fs_sb_info is wasted due to aligning after Boolean
   type variables by compiler.
2. if we continuously add new flag into f2fs_sb_info, structure will be messed
   up.

So in this patch, we try to:
1. switch s_dirty to Boolean type variable since it has two status 0/1.
2. merge s_dirty/need_fsck/s_closing/por_doing variables into s_flag.
3. introduce an enum type which can indicate different states of sbi.
4. use new introduced universal interfaces is_sbi_flag_set/{set,clear}_sbi_flag
   to operate flags for sbi.

After that, above issues will be fixed.

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

f2fs: do not skip any writes under memory pressure

2014-11-10T14:51:38+00:00

Under memory pressure, let's avoid skipping data writes.

Signed-off-by: Jaegeuk Kim

f2fs: introduce f2fs_change_bit to simplify the change bit logic

2014-11-04T00:07:36+00:00

Introduce f2fs_change_bit to simplify the change bit logic in
function set_to_next_nat{sit}.

Signed-off-by: Gu Zheng 
Signed-off-by: Jaegeuk Kim

f2fs: support atomic writes

2014-10-07T00:39:50+00:00

This patch introduces a very limited functionality for atomic write support.
In order to support atomic write, this patch adds two ioctls:
 o F2FS_IOC_START_ATOMIC_WRITE
 o F2FS_IOC_COMMIT_ATOMIC_WRITE

The database engine should be aware of the following sequence.
1. open
 -> ioctl(F2FS_IOC_START_ATOMIC_WRITE);
2. writes
  : all the written data will be treated as atomic pages.
3. commit
 -> ioctl(F2FS_IOC_COMMIT_ATOMIC_WRITE);
  : this flushes all the data blocks to the disk, which will be shown all or
  nothing by f2fs recovery procedure.
4. repeat to #2.

The IO pattens should be:

  ,- START_ATOMIC_WRITE                  ,- COMMIT_ATOMIC_WRITE
 CP | D D D D D D | FSYNC | D D D D | FSYNC ...
                      `- COMMIT_ATOMIC_WRITE

Signed-off-by: Jaegeuk Kim

f2fs: potential shift wrapping buf in f2fs_trim_fs()

2014-09-30T22:34:56+00:00

My static checker complains that segment is a u64 but only the lower 31
bits can be used before we hit a shift wrapping bug.

Signed-off-by: Dan Carpenter 
Signed-off-by: Jaegeuk Kim

f2fs: check the use of macros on block counts and addresses

2014-09-30T22:34:47+00:00

This patch cleans up the existing and new macros for readability.

Rule is like this.

         ,-----------------------------------------> MAX_BLKADDR -,
         |  ,------------- TOTAL_BLKS ----------------------------,
         |  |                                                     |
         |  ,- seg0_blkaddr   ,----- sit/nat/ssa/main blkaddress  |
block    |  | (SEG0_BLKADDR)  | | | |   (e.g., MAIN_BLKADDR)      |
address  0..x................ a b c d .............................
            |                                                     |
global seg# 0...................... m .............................
            |                       |                             |
            |                       `------- MAIN_SEGS -----------'
            `-------------- TOTAL_SEGS ---------------------------'
                                    |                             |
 seg#                               0..........xx..................

= Note =
 o GET_SEGNO_FROM_SEG0 : blk address -> global segno
 o GET_SEGNO           : blk address -> segno
 o START_BLOCK         : segno -> starting block address

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

f2fs: use more free segments until SSR is activated

2014-09-23T18:10:24+00:00

Previously, f2fs activates SSR if the # of free segments reaches to the # of
overprovisioned segments.
In this case, SSR starts to use dirty segments only, so that the overprovisoned
space cannot be selected for new data.
This means that we have no chance to utilizae the overprovisioned space at all.

This patch fixes that by allowing LFS allocations until the # of free segments
reaches to the last threshold, reserved space.

Signed-off-by: Jaegeuk Kim