[PATCH 1/2] f2fs: use rw_semaphore to protect SIT cache

From: Chao Yu
Date: Mon Oct 30 2017 - 05:50:55 EST

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There are some cases user didn't update SIT cache under this lock,
so let's use rw_semaphore instead of mutex to enhance concurrently
accessing.

Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
---
fs/f2fs/gc.c | 12 ++++++------
fs/f2fs/segment.c | 34 +++++++++++++++++++---------------
fs/f2fs/segment.h | 2 +-
3 files changed, 26 insertions(+), 22 deletions(-)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index a2e5278b6c86..7af91c423456 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -456,10 +456,10 @@ static int check_valid_map(struct f2fs_sb_info *sbi,
struct seg_entry *sentry;
int ret;

- mutex_lock(&sit_i->sentry_lock);
+ down_read(&sit_i->sentry_lock);
sentry = get_seg_entry(sbi, segno);
ret = f2fs_test_bit(offset, sentry->cur_valid_map);
- mutex_unlock(&sit_i->sentry_lock);
+ up_read(&sit_i->sentry_lock);
return ret;
}

@@ -893,10 +893,10 @@ static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
struct sit_info *sit_i = SIT_I(sbi);
int ret;

- mutex_lock(&sit_i->sentry_lock);
+ down_write(&sit_i->sentry_lock);
ret = DIRTY_I(sbi)->v_ops->get_victim(sbi, victim, gc_type,
NO_CHECK_TYPE, LFS);
- mutex_unlock(&sit_i->sentry_lock);
+ up_write(&sit_i->sentry_lock);
return ret;
}

@@ -944,8 +944,8 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
/*
* this is to avoid deadlock:
* - lock_page(sum_page) - f2fs_replace_block
- * - check_valid_map() - mutex_lock(sentry_lock)
- * - mutex_lock(sentry_lock) - change_curseg()
+ * - check_valid_map() - down_write(sentry_lock)
+ * - down_read(sentry_lock) - change_curseg()
* - lock_page(sum_page)
*/
if (type == SUM_TYPE_NODE)
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 873da0e4a75a..f4ffcfc918f7 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1911,14 +1911,14 @@ void invalidate_blocks(struct f2fs_sb_info *sbi, block_t addr)
return;

/* add it into sit main buffer */
- mutex_lock(&sit_i->sentry_lock);
+ down_write(&sit_i->sentry_lock);

update_sit_entry(sbi, addr, -1);

/* add it into dirty seglist */
locate_dirty_segment(sbi, segno);

- mutex_unlock(&sit_i->sentry_lock);
+ up_write(&sit_i->sentry_lock);
}

bool is_checkpointed_data(struct f2fs_sb_info *sbi, block_t blkaddr)
@@ -1931,7 +1931,7 @@ bool is_checkpointed_data(struct f2fs_sb_info *sbi, block_t blkaddr)
if (blkaddr == NEW_ADDR || blkaddr == NULL_ADDR)
return true;

- mutex_lock(&sit_i->sentry_lock);
+ down_read(&sit_i->sentry_lock);

segno = GET_SEGNO(sbi, blkaddr);
se = get_seg_entry(sbi, segno);
@@ -1940,7 +1940,7 @@ bool is_checkpointed_data(struct f2fs_sb_info *sbi, block_t blkaddr)
if (f2fs_test_bit(offset, se->ckpt_valid_map))
is_cp = true;

- mutex_unlock(&sit_i->sentry_lock);
+ up_read(&sit_i->sentry_lock);

return is_cp;
}
@@ -2336,12 +2336,16 @@ void allocate_new_segments(struct f2fs_sb_info *sbi)
unsigned int old_segno;
int i;

+ down_write(&SIT_I(sbi)->sentry_lock);
+
for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
curseg = CURSEG_I(sbi, i);
old_segno = curseg->segno;
SIT_I(sbi)->s_ops->allocate_segment(sbi, i, true);
locate_dirty_segment(sbi, old_segno);
}
+
+ up_write(&SIT_I(sbi)->sentry_lock);
}

static const struct segment_allocation default_salloc_ops = {
@@ -2353,14 +2357,14 @@ bool exist_trim_candidates(struct f2fs_sb_info *sbi, struct cp_control *cpc)
__u64 trim_start = cpc->trim_start;
bool has_candidate = false;

- mutex_lock(&SIT_I(sbi)->sentry_lock);
+ down_write(&SIT_I(sbi)->sentry_lock);
for (; cpc->trim_start <= cpc->trim_end; cpc->trim_start++) {
if (add_discard_addrs(sbi, cpc, true)) {
has_candidate = true;
break;
}
}
- mutex_unlock(&SIT_I(sbi)->sentry_lock);
+ up_write(&SIT_I(sbi)->sentry_lock);

cpc->trim_start = trim_start;
return has_candidate;
@@ -2520,7 +2524,7 @@ void allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
struct curseg_info *curseg = CURSEG_I(sbi, type);

mutex_lock(&curseg->curseg_mutex);
- mutex_lock(&sit_i->sentry_lock);
+ down_write(&sit_i->sentry_lock);

*new_blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);

@@ -2554,7 +2558,7 @@ void allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
locate_dirty_segment(sbi, GET_SEGNO(sbi, old_blkaddr));
locate_dirty_segment(sbi, GET_SEGNO(sbi, *new_blkaddr));

- mutex_unlock(&sit_i->sentry_lock);
+ up_write(&sit_i->sentry_lock);

if (page && IS_NODESEG(type)) {
fill_node_footer_blkaddr(page, NEXT_FREE_BLKADDR(sbi, curseg));
@@ -2712,7 +2716,7 @@ void __f2fs_replace_block(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
curseg = CURSEG_I(sbi, type);

mutex_lock(&curseg->curseg_mutex);
- mutex_lock(&sit_i->sentry_lock);
+ down_write(&sit_i->sentry_lock);

old_cursegno = curseg->segno;
old_blkoff = curseg->next_blkoff;
@@ -2744,7 +2748,7 @@ void __f2fs_replace_block(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
curseg->next_blkoff = old_blkoff;
}

- mutex_unlock(&sit_i->sentry_lock);
+ up_write(&sit_i->sentry_lock);
mutex_unlock(&curseg->curseg_mutex);
}

@@ -3199,7 +3203,7 @@ void flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
bool to_journal = true;
struct seg_entry *se;

- mutex_lock(&sit_i->sentry_lock);
+ down_write(&sit_i->sentry_lock);

if (!sit_i->dirty_sentries)
goto out;
@@ -3293,7 +3297,7 @@ void flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)

cpc->trim_start = trim_start;
}
- mutex_unlock(&sit_i->sentry_lock);
+ up_write(&sit_i->sentry_lock);

set_prefree_as_free_segments(sbi);
}
@@ -3386,7 +3390,7 @@ static int build_sit_info(struct f2fs_sb_info *sbi)
sit_i->sents_per_block = SIT_ENTRY_PER_BLOCK;
sit_i->elapsed_time = le64_to_cpu(sbi->ckpt->elapsed_time);
sit_i->mounted_time = ktime_get_real_seconds();
- mutex_init(&sit_i->sentry_lock);
+ init_rwsem(&sit_i->sentry_lock);
return 0;
}

@@ -3627,7 +3631,7 @@ static void init_min_max_mtime(struct f2fs_sb_info *sbi)
struct sit_info *sit_i = SIT_I(sbi);
unsigned int segno;

- mutex_lock(&sit_i->sentry_lock);
+ down_write(&sit_i->sentry_lock);

sit_i->min_mtime = LLONG_MAX;

@@ -3644,7 +3648,7 @@ static void init_min_max_mtime(struct f2fs_sb_info *sbi)
sit_i->min_mtime = mtime;
}
sit_i->max_mtime = get_mtime(sbi);
- mutex_unlock(&sit_i->sentry_lock);
+ up_write(&sit_i->sentry_lock);
}

int build_segment_manager(struct f2fs_sb_info *sbi)
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index 8d93652d5b6a..245acb34cab5 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -231,7 +231,7 @@ struct sit_info {
unsigned long *dirty_sentries_bitmap; /* bitmap for dirty sentries */
unsigned int dirty_sentries; /* # of dirty sentries */
unsigned int sents_per_block; /* # of SIT entries per block */
- struct mutex sentry_lock; /* to protect SIT cache */
+ struct rw_semaphore sentry_lock; /* to protect SIT cache */
struct seg_entry *sentries; /* SIT segment-level cache */
struct sec_entry *sec_entries; /* SIT section-level cache */

--
2.13.1.388.g69e6b9b4f4a9

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