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f2fs: use spinlock for segmap_lock instead of rwlock

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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 <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Chao Yu
2015-02-11 18:20:38 +08:00
committed by Jaegeuk Kim
parent f1a3b98e73
commit 1a118ccfd6
2 changed files with 12 additions and 12 deletions
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6
fs/f2fs/segment.c
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@@ -800,7 +800,7 @@ static void get_new_segment(struct f2fs_sb_info *sbi,
int go_left = 0;
int i;
write_lock(&free_i->segmap_lock);
spin_lock(&free_i->segmap_lock);
if (!new_sec && ((*newseg + 1) % sbi->segs_per_sec)) {
segno = find_next_zero_bit(free_i->free_segmap,
@@ -873,7 +873,7 @@ got_it:
f2fs_bug_on(sbi, test_bit(segno, free_i->free_segmap));
__set_inuse(sbi, segno);
*newseg = segno;
write_unlock(&free_i->segmap_lock);
spin_unlock(&free_i->segmap_lock);
}
static void reset_curseg(struct f2fs_sb_info *sbi, int type, int modified)
@@ -1923,7 +1923,7 @@ static int build_free_segmap(struct f2fs_sb_info *sbi)
free_i->start_segno = GET_SEGNO_FROM_SEG0(sbi, MAIN_BLKADDR(sbi));
free_i->free_segments = 0;
free_i->free_sections = 0;
rwlock_init(&free_i->segmap_lock);
spin_lock_init(&free_i->segmap_lock);
return 0;
}