From 1a118ccfd60fc78e64c0a3ab9e85075545839d6e Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Wed, 11 Feb 2015 18:20:38 +0800 Subject: [PATCH] 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 Signed-off-by: Jaegeuk Kim --- fs/f2fs/segment.c | 6 +++--- fs/f2fs/segment.h | 18 +++++++++--------- 2 files changed, 12 insertions(+), 12 deletions(-) diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index c9d314f44568..daee4ab913da 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -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; } diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h index ba858ca01445..7fd35111cf62 100644 --- a/fs/f2fs/segment.h +++ b/fs/f2fs/segment.h @@ -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,