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/segment.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'fs/f2fs/segment.c') diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 621b9b3d320b..c695ff462ee6 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -1210,11 +1210,11 @@ void stop_discard_thread(struct f2fs_sb_info *sbi) } /* This comes from f2fs_put_super and f2fs_trim_fs */ -void f2fs_wait_discard_bios(struct f2fs_sb_info *sbi) +void f2fs_wait_discard_bios(struct f2fs_sb_info *sbi, bool umount) { __issue_discard_cmd(sbi, false); __drop_discard_cmd(sbi); - __wait_discard_cmd(sbi, false); + __wait_discard_cmd(sbi, !umount); } static void mark_discard_range_all(struct f2fs_sb_info *sbi) @@ -2244,7 +2244,7 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range) } /* It's time to issue all the filed discards */ mark_discard_range_all(sbi); - f2fs_wait_discard_bios(sbi); + f2fs_wait_discard_bios(sbi, false); out: range->len = F2FS_BLK_TO_BYTES(cpc.trimmed); return err; -- cgit 1.4.1