On 02/18, Shin'ichiro Kawasaki wrote: > From: Shin'ichiro Kawasaki via Linux-f2fs-devel > <[email protected]> > > A lockdep WARN is observed recently under the following steps: > > 1) Create a zoned TCMU device > 2) Create a f2fs filesystem on the zoned TCMU device and mount it > 3) Fill the filesystem with files and trigger GC > 4) Unmout the filesystem > 5) Remove the zoned TCMU device > > The lockdep WARN indicates that a circular lock depedency formed by four > contexts, as described below. > > a) TCMU device removal context: > - call del_gendisk() to get q->q_usage_counter > - call start_flush_work() to get work_completion of wb->dwork > b) f2fs writeback context: > - in wb_workfn(), which holds work_completion of wb->dwork > - call f2fs_balance_fs() to get sbi->gc_lock > c) f2fs vfs_write context: > - call f2fs_gc() to get sbi->gc_lock > - call f2fs_write_checkpoint() to get sbi->cp_global_sem > d) f2fs mount context: > - call recover_fsync_data() to get sbi->cp_global_sem > - call f2fs_check_and_fix_write_pointer() to call blkdev_report_zones() > that goes down to blk_mq_alloc_request and get q->q_usage_counter > > To suppress the WARN, cut the dependency d) between sbi->cp_global_sem > and q->q_usage_counter. For that purpose, move the > f2fs_check_and_fix_write_pointer() call outside of the critical section > of sbi->cp_global_sem in f2fs_recovery_fsync_data(). This change is fine > because the write pointer fix operation only affects the main segments > and does not interact with the check point metadata. Furthermore, > conflicts between the write pointer fix operation and data/node flush > operations remain protected by SBI_POR_DOING. > > Fixes: c426d99127b1 ("f2fs: Check write pointer consistency of open zones") > Reviewed-by: Damien Le Moal <[email protected]> > Signed-off-by: Shin'ichiro Kawasaki <[email protected]> > --- > fs/f2fs/recovery.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c > index a26071f2b0bc..87fd6cd436fe 100644 > --- a/fs/f2fs/recovery.c > +++ b/fs/f2fs/recovery.c > @@ -922,6 +922,8 @@ int f2fs_recover_fsync_data(struct f2fs_sb_info *sbi, > bool check_only) > truncate_inode_pages_final(META_MAPPING(sbi)); > } > > + f2fs_up_write_trace(&sbi->cp_global_sem, &lc); > + > /* > * If fsync data succeeds or there is no fsync data to recover, > * and the f2fs is not read only, check and fix zoned block devices' > @@ -933,8 +935,6 @@ int f2fs_recover_fsync_data(struct f2fs_sb_info *sbi, > bool check_only) > if (!err) > clear_sbi_flag(sbi, SBI_POR_DOING); > > - f2fs_up_write_trace(&sbi->cp_global_sem, &lc); > -
This was a guard to prevent checkpoint during f2fs_check_and_fix_write_pointer() where it changes the checkpoint as well? > /* let's drop all the directory inodes for clean checkpoint */ > destroy_fsync_dnodes(&dir_list, err); > > -- > 2.49.0 _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
