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| author | majianpeng <majianpeng@gmail.com> | 2013-01-14 20:08:16 +0800 |
|---|---|---|
| committer | Jaegeuk Kim <jaegeuk.kim@samsung.com> | 2013-01-15 20:18:29 +0900 |
| commit | 66af62ce7588736ae65edfdb1c0df597775c4d21 (patch) | |
| tree | 40c696804e7d628161889a7505ff164debf83674 /fs | |
| parent | fa9150a84ca333f68127097c4fa1eda4b3913a22 (diff) | |
| download | linux-66af62ce7588736ae65edfdb1c0df597775c4d21.tar.gz linux-66af62ce7588736ae65edfdb1c0df597775c4d21.tar.bz2 linux-66af62ce7588736ae65edfdb1c0df597775c4d21.zip | |
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.c | 23 |
1 files changed, 11 insertions, 12 deletions
diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c index b8ed7a72c6e9..73f034a94182 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); } |