提交 66af62ce 编写于 作者: M majianpeng 提交者: Jaegeuk Kim

f2fs: add global mutex_lock to protect f2fs_stat_list

There is an race condition between umounting f2fs and reading f2fs/status, which
results in oops.

Fox example:
Thread A			Thread B
umount f2fs 			cat f2fs/status

f2fs_destroy_stats() {		stat_show() {
				 list_for_each_entry_safe(&f2fs_stat_list)
 list_del(&si->stat_list);
 mutex_lock(&si->stat_lock);
 si->sbi = NULL;
 mutex_unlock(&si->stat_lock);
 kfree(sbi->stat_info);
} 				 mutex_lock(&si->stat_lock) <- si is gone.
				 ...
				}

Solution with a global lock: f2fs_stat_mutex:
Thread A			Thread B
umount f2fs 			cat f2fs/status

f2fs_destroy_stats() {		stat_show() {
 mutex_lock(&f2fs_stat_mutex);
 list_del(&si->stat_list);
 mutex_unlock(&f2fs_stat_mutex);
 kfree(sbi->stat_info);		 mutex_lock(&f2fs_stat_mutex);
}				 list_for_each_entry_safe(&f2fs_stat_list)
				 ...
				 mutex_unlock(&f2fs_stat_mutex);
				}
Signed-off-by: NJianpeng Ma <majianpeng@gmail.com>
[jaegeuk.kim@samsung.com: fix typos, description, and remove the existing lock]
Signed-off-by: NJaegeuk Kim <jaegeuk.kim@samsung.com>
上级 fa9150a8
......@@ -26,6 +26,7 @@
static LIST_HEAD(f2fs_stat_list);
static struct dentry *debugfs_root;
static DEFINE_MUTEX(f2fs_stat_mutex);
static void update_general_status(struct f2fs_sb_info *sbi)
{
......@@ -180,13 +181,9 @@ static int stat_show(struct seq_file *s, void *v)
int i = 0;
int j;
mutex_lock(&f2fs_stat_mutex);
list_for_each_entry_safe(si, next, &f2fs_stat_list, stat_list) {
mutex_lock(&si->stat_lock);
if (!si->sbi) {
mutex_unlock(&si->stat_lock);
continue;
}
update_general_status(si->sbi);
seq_printf(s, "\n=====[ partition info. #%d ]=====\n", i++);
......@@ -286,8 +283,8 @@ static int stat_show(struct seq_file *s, void *v)
seq_printf(s, "\nMemory: %u KB = static: %u + cached: %u\n",
(si->base_mem + si->cache_mem) >> 10,
si->base_mem >> 10, si->cache_mem >> 10);
mutex_unlock(&si->stat_lock);
}
mutex_unlock(&f2fs_stat_mutex);
return 0;
}
......@@ -313,9 +310,6 @@ static int init_stats(struct f2fs_sb_info *sbi)
return -ENOMEM;
si = sbi->stat_info;
mutex_init(&si->stat_lock);
list_add_tail(&si->stat_list, &f2fs_stat_list);
si->all_area_segs = le32_to_cpu(raw_super->segment_count);
si->sit_area_segs = le32_to_cpu(raw_super->segment_count_sit);
si->nat_area_segs = le32_to_cpu(raw_super->segment_count_nat);
......@@ -325,6 +319,11 @@ static int init_stats(struct f2fs_sb_info *sbi)
si->main_area_zones = si->main_area_sections /
le32_to_cpu(raw_super->secs_per_zone);
si->sbi = sbi;
mutex_lock(&f2fs_stat_mutex);
list_add_tail(&si->stat_list, &f2fs_stat_list);
mutex_unlock(&f2fs_stat_mutex);
return 0;
}
......@@ -347,10 +346,10 @@ void f2fs_destroy_stats(struct f2fs_sb_info *sbi)
{
struct f2fs_stat_info *si = sbi->stat_info;
mutex_lock(&f2fs_stat_mutex);
list_del(&si->stat_list);
mutex_lock(&si->stat_lock);
si->sbi = NULL;
mutex_unlock(&si->stat_lock);
mutex_unlock(&f2fs_stat_mutex);
kfree(sbi->stat_info);
}
......
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册