f2fs: use spinlock for segmap_lock instead of rwlock
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>
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index c9d314f..daee4ab 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -800,7 +800,7 @@
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 @@
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 @@
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;
}
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index ba858ca..7fd3511 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -208,7 +208,7 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
{
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,
