From 638164a2718f337ea224b747cf5977ef143166a4 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Mon, 2 Oct 2017 02:50:16 +0800 Subject: [PATCH] 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 +- fs/f2fs/segment.c | 6 +++--- fs/f2fs/super.c | 2 +- 3 files changed, 5 insertions(+), 5 deletions(-) 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); 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; diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 89f61eb3d167..933c3d529e65 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -801,7 +801,7 @@ static void f2fs_put_super(struct super_block *sb) } /* be sure to wait for any on-going discard commands */ - f2fs_wait_discard_bios(sbi); + f2fs_wait_discard_bios(sbi, true); if (f2fs_discard_en(sbi) && !sbi->discard_blks) { struct cp_control cpc = { -- 2.20.1