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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
View File

@ -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;
}

18
fs/f2fs/segment.h
View File

@ -208,7 +208,7 @@ struct free_segmap_info {
unsigned int start_segno; /* start segment number logically */
unsigned int free_segments; /* # of free segments */
unsigned int free_sections; /* # of free sections */
rwlock_t segmap_lock; /* free segmap lock */
spinlock_t segmap_lock; /* free segmap lock */
unsigned long *free_segmap; /* free segment bitmap */
unsigned long *free_secmap; /* free section bitmap */
};
@ -319,9 +319,9 @@ static inline unsigned int find_next_inuse(struct free_segmap_info *free_i,
unsigned int max, unsigned int segno)
{
unsigned int ret;
read_lock(&free_i->segmap_lock);
spin_lock(&free_i->segmap_lock);
ret = find_next_bit(free_i->free_segmap, max, segno);
read_unlock(&free_i->segmap_lock);
spin_unlock(&free_i->segmap_lock);
return ret;
}
@ -332,7 +332,7 @@ static inline void __set_free(struct f2fs_sb_info *sbi, unsigned int segno)
unsigned int start_segno = secno * sbi->segs_per_sec;
unsigned int next;
write_lock(&free_i->segmap_lock);
spin_lock(&free_i->segmap_lock);
clear_bit(segno, free_i->free_segmap);
free_i->free_segments++;
@ -341,7 +341,7 @@ static inline void __set_free(struct f2fs_sb_info *sbi, unsigned int segno)
clear_bit(secno, free_i->free_secmap);
free_i->free_sections++;
}
write_unlock(&free_i->segmap_lock);
spin_unlock(&free_i->segmap_lock);
}
static inline void __set_inuse(struct f2fs_sb_info *sbi,
@ -363,7 +363,7 @@ static inline void __set_test_and_free(struct f2fs_sb_info *sbi,
unsigned int start_segno = secno * sbi->segs_per_sec;
unsigned int next;
write_lock(&free_i->segmap_lock);
spin_lock(&free_i->segmap_lock);
if (test_and_clear_bit(segno, free_i->free_segmap)) {
free_i->free_segments++;
@ -374,7 +374,7 @@ static inline void __set_test_and_free(struct f2fs_sb_info *sbi,
free_i->free_sections++;
}
}
write_unlock(&free_i->segmap_lock);
spin_unlock(&free_i->segmap_lock);
}
static inline void __set_test_and_inuse(struct f2fs_sb_info *sbi,
@ -382,13 +382,13 @@ static inline void __set_test_and_inuse(struct f2fs_sb_info *sbi,
{
struct free_segmap_info *free_i = FREE_I(sbi);
unsigned int secno = segno / sbi->segs_per_sec;
write_lock(&free_i->segmap_lock);
spin_lock(&free_i->segmap_lock);
if (!test_and_set_bit(segno, free_i->free_segmap)) {
free_i->free_segments--;
if (!test_and_set_bit(secno, free_i->free_secmap))
free_i->free_sections--;
}
write_unlock(&free_i->segmap_lock);
spin_unlock(&free_i->segmap_lock);
}
static inline void get_sit_bitmap(struct f2fs_sb_info *sbi,