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authormajianpeng <majianpeng@gmail.com>2013-01-14 20:08:16 +0800
committerJaegeuk Kim <jaegeuk.kim@samsung.com>2013-01-15 20:18:29 +0900
commit66af62ce7588736ae65edfdb1c0df597775c4d21 (patch)
tree40c696804e7d628161889a7505ff164debf83674 /fs
parentfa9150a84ca333f68127097c4fa1eda4b3913a22 (diff)
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: Jianpeng Ma <majianpeng@gmail.com> [jaegeuk.kim@samsung.com: fix typos, description, and remove the existing lock] Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/f2fs/debug.c23
1 files changed, 11 insertions, 12 deletions
diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
index b8ed7a72c6e..73f034a9418 100644
--- a/fs/f2fs/debug.c
+++ b/fs/f2fs/debug.c
@@ -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);
}