On 08/14/2012 08:59 PM, Marco Stornelli wrote: > Il 14/08/2012 07:01, liub.liubo@xxxxxxxxx ha scritto: >> From: Liu Bo <bo.li.liu@xxxxxxxxxx> >> >> I found this while testing xfstests 068, the story is >> >> t1 t2 >> sys_sync thaw_super >> iterate_supers >> down_read(sb->s_umount) down_write(sb->s_umount) --->wait for t1 >> sync_fs (with wait mode) >> start_transaction >> sb_start_intwrite --------------------> wait for t2 to set s_writers.frozen to SB_UNFROZEN >> >> In this patch, I add an helper sb_start_intwrite_trylock() and use it before we >> start_transaction in sync_fs() with wait mode so that we won't hit the deadlock. >> > > IMHO, we should avoid to call the sync operation on a frozen fs. The freeze operation, indeed, already include a sync operation. > According to man page, no other operation should modify the fs after the freeze. > So for me the modification is inside sync_filesystem (and sync_one_sb). Do you mean that we should add the trylock check in sync_filesystem? But it seems to be useless because we already run into down_read(sb->s_umount) before starting sync_one_sb(). thanks, liubo > > Marco > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
