On Tue, Jan 18, 2022 at 02:00:41PM +1100, Dave Chinner wrote: > > IOW, how far is xfs_inode_mark_reclaimable() from being callable in RCU > > callback context? > > AIUI, not very close at all, > > I'm pretty sure we can't put it under RCU callback context at all > because xfs_fs_destroy_inode() can take sleeping locks, perform > transactions, do IO, run rcu_read_lock() critical sections, etc. > This means that needs to run an a full task context and so can't run > from RCU callback context at all. Umm... AFAICS, this pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino)); spin_lock(&pag->pag_ici_lock); spin_lock(&ip->i_flags_lock); trace_xfs_inode_set_reclaimable(ip); ip->i_flags &= ~(XFS_NEED_INACTIVE | XFS_INACTIVATING); ip->i_flags |= XFS_IRECLAIMABLE; xfs_perag_set_inode_tag(pag, XFS_INO_TO_AGINO(mp, ip->i_ino), XFS_ICI_RECLAIM_TAG); spin_unlock(&ip->i_flags_lock); spin_unlock(&pag->pag_ici_lock); xfs_perag_put(pag); in the end of xfs_inodegc_set_reclaimable() could go into ->free_inode() just fine. It's xfs_inodegc_queue() I'm not sure about - the part about flush_work() in there... I'm not familiar with that code; could you point me towards some docs/old postings/braindump/whatnot?
