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Subject[PATCH] f2fs: change to use rwsem for gc_mutex
Date
Mutex lock won't serialize callers, in order to avoid starving of unlucky
caller, let's use rwsem lock instead.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
fs/f2fs/f2fs.h | 5 ++++-
fs/f2fs/file.c | 12 ++++++------
fs/f2fs/gc.c | 12 ++++++------
fs/f2fs/segment.c | 6 +++---
fs/f2fs/super.c | 16 ++++++++--------
5 files changed, 27 insertions(+), 24 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index e7208442d32a..61d62cd06449 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1391,7 +1391,10 @@ struct f2fs_sb_info {
struct f2fs_mount_info mount_opt; /* mount options */

/* for cleaning operations */
- struct mutex gc_mutex; /* mutex for GC */
+ struct rw_semaphore gc_lock; /*
+ * semaphore for GC, avoid
+ * race between GC and GC or CP
+ */
struct f2fs_gc_kthread *gc_thread; /* GC thread */
unsigned int cur_victim_sec; /* current victim section num */
unsigned int gc_mode; /* current GC state */
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 0dff22566a1d..86ddbb55d2b1 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1642,7 +1642,7 @@ static int expand_inode_data(struct inode *inode, loff_t offset,
next_alloc:
if (has_not_enough_free_secs(sbi, 0,
GET_SEC_FROM_SEG(sbi, overprovision_segments(sbi)))) {
- mutex_lock(&sbi->gc_mutex);
+ down_write(&sbi->gc_lock);
err = f2fs_gc(sbi, true, false, NULL_SEGNO);
if (err && err != -ENODATA && err != -EAGAIN)
goto out_err;
@@ -2450,12 +2450,12 @@ static int f2fs_ioc_gc(struct file *filp, unsigned long arg)
return ret;

if (!sync) {
- if (!mutex_trylock(&sbi->gc_mutex)) {
+ if (!down_write_trylock(&sbi->gc_lock)) {
ret = -EBUSY;
goto out;
}
} else {
- mutex_lock(&sbi->gc_mutex);
+ down_write(&sbi->gc_lock);
}

ret = f2fs_gc(sbi, sync, true, NULL_SEGNO);
@@ -2493,12 +2493,12 @@ static int f2fs_ioc_gc_range(struct file *filp, unsigned long arg)

do_more:
if (!range.sync) {
- if (!mutex_trylock(&sbi->gc_mutex)) {
+ if (!down_write_trylock(&sbi->gc_lock)) {
ret = -EBUSY;
goto out;
}
} else {
- mutex_lock(&sbi->gc_mutex);
+ down_write(&sbi->gc_lock);
}

ret = f2fs_gc(sbi, range.sync, true, GET_SEGNO(sbi, range.start));
@@ -2929,7 +2929,7 @@ static int f2fs_ioc_flush_device(struct file *filp, unsigned long arg)
end_segno = min(start_segno + range.segments, dev_end_segno);

while (start_segno < end_segno) {
- if (!mutex_trylock(&sbi->gc_mutex)) {
+ if (!down_write_trylock(&sbi->gc_lock)) {
ret = -EBUSY;
goto out;
}
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index c43181ef98c4..67eca7c2d983 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -78,18 +78,18 @@ static int gc_thread_func(void *data)
*/
if (sbi->gc_mode == GC_URGENT) {
wait_ms = gc_th->urgent_sleep_time;
- mutex_lock(&sbi->gc_mutex);
+ down_write(&sbi->gc_lock);
goto do_gc;
}

- if (!mutex_trylock(&sbi->gc_mutex)) {
+ if (!down_write_trylock(&sbi->gc_lock)) {
stat_other_skip_bggc_count(sbi);
goto next;
}

if (!is_idle(sbi, GC_TIME)) {
increase_sleep_time(gc_th, &wait_ms);
- mutex_unlock(&sbi->gc_mutex);
+ up_write(&sbi->gc_lock);
stat_io_skip_bggc_count(sbi);
goto next;
}
@@ -1370,7 +1370,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
reserved_segments(sbi),
prefree_segments(sbi));

- mutex_unlock(&sbi->gc_mutex);
+ up_write(&sbi->gc_lock);

put_gc_inode(&gc_list);

@@ -1409,9 +1409,9 @@ static int free_segment_range(struct f2fs_sb_info *sbi, unsigned int start,
.iroot = RADIX_TREE_INIT(gc_list.iroot, GFP_NOFS),
};

- mutex_lock(&sbi->gc_mutex);
+ down_write(&sbi->gc_lock);
do_garbage_collect(sbi, segno, &gc_list, FG_GC);
- mutex_unlock(&sbi->gc_mutex);
+ up_write(&sbi->gc_lock);
put_gc_inode(&gc_list);

if (get_valid_blocks(sbi, segno, true))
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 311fe4937f6a..6d03b89242f5 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -504,7 +504,7 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need)
* dir/node pages without enough free segments.
*/
if (has_not_enough_free_secs(sbi, 0, 0)) {
- mutex_lock(&sbi->gc_mutex);
+ down_write(&sbi->gc_lock);
f2fs_gc(sbi, false, false, NULL_SEGNO);
}
}
@@ -2860,9 +2860,9 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
if (sbi->discard_blks == 0)
goto out;

- mutex_lock(&sbi->gc_mutex);
+ down_write(&sbi->gc_lock);
err = f2fs_write_checkpoint(sbi, &cpc);
- mutex_unlock(&sbi->gc_mutex);
+ up_write(&sbi->gc_lock);
if (err)
goto out;

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 593dc3d2b80b..65a7a432dfee 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1238,9 +1238,9 @@ int f2fs_sync_fs(struct super_block *sb, int sync)

cpc.reason = __get_cp_reason(sbi);

- mutex_lock(&sbi->gc_mutex);
+ down_write(&sbi->gc_lock);
err = f2fs_write_checkpoint(sbi, &cpc);
- mutex_unlock(&sbi->gc_mutex);
+ up_write(&sbi->gc_lock);
}
f2fs_trace_ios(NULL, 1);

@@ -1621,7 +1621,7 @@ static int f2fs_disable_checkpoint(struct f2fs_sb_info *sbi)
f2fs_update_time(sbi, DISABLE_TIME);

while (!f2fs_time_over(sbi, DISABLE_TIME)) {
- mutex_lock(&sbi->gc_mutex);
+ down_write(&sbi->gc_lock);
err = f2fs_gc(sbi, true, false, NULL_SEGNO);
if (err == -ENODATA) {
err = 0;
@@ -1643,7 +1643,7 @@ static int f2fs_disable_checkpoint(struct f2fs_sb_info *sbi)
goto restore_flag;
}

- mutex_lock(&sbi->gc_mutex);
+ down_write(&sbi->gc_lock);
cpc.reason = CP_PAUSE;
set_sbi_flag(sbi, SBI_CP_DISABLED);
err = f2fs_write_checkpoint(sbi, &cpc);
@@ -1655,7 +1655,7 @@ static int f2fs_disable_checkpoint(struct f2fs_sb_info *sbi)
spin_unlock(&sbi->stat_lock);

out_unlock:
- mutex_unlock(&sbi->gc_mutex);
+ up_write(&sbi->gc_lock);
restore_flag:
sbi->sb->s_flags = s_flags; /* Restore MS_RDONLY status */
return err;
@@ -1663,12 +1663,12 @@ static int f2fs_disable_checkpoint(struct f2fs_sb_info *sbi)

static void f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
{
- mutex_lock(&sbi->gc_mutex);
+ down_write(&sbi->gc_lock);
f2fs_dirty_to_prefree(sbi);

clear_sbi_flag(sbi, SBI_CP_DISABLED);
set_sbi_flag(sbi, SBI_IS_DIRTY);
- mutex_unlock(&sbi->gc_mutex);
+ up_write(&sbi->gc_lock);

f2fs_sync_fs(sbi->sb, 1);
}
@@ -3398,7 +3398,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)

/* init f2fs-specific super block info */
sbi->valid_super_block = valid_super_block;
- mutex_init(&sbi->gc_mutex);
+ init_rwsem(&sbi->gc_lock);
mutex_init(&sbi->writepages);
mutex_init(&sbi->cp_mutex);
mutex_init(&sbi->resize_mutex);
--
2.18.0.rc1
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