From 638164a2718f337ea224b747cf5977ef143166a4 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Mon, 2 Oct 2017 02:50:16 +0800 Subject: f2fs: fix potential panic during fstrim As Ju Hyung Park reported: "When 'fstrim' is called for manual trim, a BUG() can be triggered randomly with this patch. I'm seeing this issue on both x86 Desktop and arm64 Android phone. On x86 Desktop, this was caused during Ubuntu boot-up. I have a cronjob installed which calls 'fstrim -v /' during boot. On arm64 Android, this was caused during GC looping with 1ms gc_min_sleep_time & gc_max_sleep_time." Root cause of this issue is that f2fs_wait_discard_bios can only be used by f2fs_put_super, because during put_super there must be no other referrers, so it can ignore discard entry's reference count when removing the entry, otherwise in other caller we will hit bug_on in __remove_discard_cmd as there may be other issuer added reference count in discard entry. Thread A Thread B - issue_discard_thread - f2fs_ioc_fitrim - f2fs_trim_fs - f2fs_wait_discard_bios - __issue_discard_cmd - __submit_discard_cmd - __wait_discard_cmd - dc->ref++ - __wait_one_discard_bio - __wait_discard_cmd - __remove_discard_cmd - f2fs_bug_on(sbi, dc->ref) Fixes: 969d1b180d987c2be02de890d0fff0f66a0e80de Reported-by: Ju Hyung Park Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/f2fs.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/f2fs/f2fs.h') diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 9a7c90386947..4b4a72f392be 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -2525,7 +2525,7 @@ void invalidate_blocks(struct f2fs_sb_info *sbi, block_t addr); bool is_checkpointed_data(struct f2fs_sb_info *sbi, block_t blkaddr); void refresh_sit_entry(struct f2fs_sb_info *sbi, block_t old, block_t new); void stop_discard_thread(struct f2fs_sb_info *sbi); -void f2fs_wait_discard_bios(struct f2fs_sb_info *sbi); +void f2fs_wait_discard_bios(struct f2fs_sb_info *sbi, bool umount); void clear_prefree_segments(struct f2fs_sb_info *sbi, struct cp_control *cpc); void release_discard_addrs(struct f2fs_sb_info *sbi); int npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra); -- cgit v1.2.3