| Message ID | 160140141157.830233.8230232141442784711.stgit@magnolia (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | xfs: fix how we deal with new intents during recovery | expand |
On Tue, Sep 29, 2020 at 10:43:31AM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong <darrick.wong@oracle.com> > > When we replay unfinished intent items that have been recovered from the > log, it's possible that the replay will cause the creation of more > deferred work items. As outlined in commit 509955823cc9c ("xfs: log > recovery should replay deferred ops in order"), later work items have an > implicit ordering dependency on earlier work items. Therefore, recovery > must replay the items (both recovered and created) in the same order > that they would have been during normal operation. > > For log recovery, we enforce this ordering by using an empty transaction > to collect deferred ops that get created in the process of recovering a > log intent item to prevent them from being committed before the rest of > the recovered intent items. After we finish committing all the > recovered log items, we allocate a transaction with an enormous block > reservation, splice our huge list of created deferred ops into that > transaction, and commit it, thereby finishing all those ops. > > This is /really/ hokey -- it's the one place in XFS where we allow > nested transactions; the splicing of the defer ops list is is inelegant > and has to be done twice per recovery function; and the broken way we > handle inode pointers and block reservations cause subtle use-after-free > and allocator problems that will be fixed by this patch and the two > patches after it. > > Therefore, replace the hokey empty transaction with a structure designed > to capture each chain of deferred ops that are created as part of > recovering a single unfinished log intent. Finally, refactor the loop > that replays those chains to do so using one transaction per chain. > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> > --- > fs/xfs/libxfs/xfs_defer.c | 89 +++++++++++++++++++++++++++++++-- > fs/xfs/libxfs/xfs_defer.h | 19 +++++++ > fs/xfs/xfs_bmap_item.c | 16 +----- > fs/xfs/xfs_extfree_item.c | 7 +-- > fs/xfs/xfs_log_recover.c | 118 +++++++++++++++++++++++++------------------- > fs/xfs/xfs_refcount_item.c | 16 +----- > fs/xfs/xfs_rmap_item.c | 7 +-- > fs/xfs/xfs_trans.h | 3 + > 8 files changed, 184 insertions(+), 91 deletions(-) > > ... > diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c > index 84f876c6d498..550d0fa8057a 100644 > --- a/fs/xfs/xfs_log_recover.c > +++ b/fs/xfs/xfs_log_recover.c > @@ -2434,37 +2434,62 @@ xlog_recover_process_data( > /* Take all the collected deferred ops and finish them in order. */ > static int > xlog_finish_defer_ops( > - struct xfs_trans *parent_tp) > + struct xfs_mount *mp, > + struct list_head *capture_list) > { > - struct xfs_mount *mp = parent_tp->t_mountp; > + struct xfs_defer_capture *dfc, *next; > struct xfs_trans *tp; > int64_t freeblks; > - uint resblks; > - int error; > + uint64_t resblks; > + int error = 0; > > - /* > - * We're finishing the defer_ops that accumulated as a result of > - * recovering unfinished intent items during log recovery. We > - * reserve an itruncate transaction because it is the largest > - * permanent transaction type. Since we're the only user of the fs > - * right now, take 93% (15/16) of the available free blocks. Use > - * weird math to avoid a 64-bit division. > - */ > - freeblks = percpu_counter_sum(&mp->m_fdblocks); > - if (freeblks <= 0) > - return -ENOSPC; > - resblks = min_t(int64_t, UINT_MAX, freeblks); > - resblks = (resblks * 15) >> 4; > - error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, resblks, > - 0, XFS_TRANS_RESERVE, &tp); > - if (error) > - return error; > - /* transfer all collected dfops to this transaction */ > - xfs_defer_move(tp, parent_tp); > + list_for_each_entry_safe(dfc, next, capture_list, dfc_list) { > + /* > + * We're finishing the defer_ops that accumulated as a result > + * of recovering unfinished intent items during log recovery. > + * We reserve an itruncate transaction because it is the > + * largest permanent transaction type. Since we're the only > + * user of the fs right now, take 93% (15/16) of the available > + * free blocks. Use weird math to avoid a 64-bit division. > + */ > + freeblks = percpu_counter_sum(&mp->m_fdblocks); > + if (freeblks <= 0) > + return -ENOSPC; > > - return xfs_trans_commit(tp); > + resblks = min_t(uint64_t, UINT_MAX, freeblks); > + resblks = (resblks * 15) >> 4; > + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, resblks, > + 0, XFS_TRANS_RESERVE, &tp); > + if (error) > + return error; > + > + /* Transfer all collected dfops to this transaction. */ This old comment is a little misleading now that we have per-intent capture lists. That nit aside, this looks good to me and the updated factoring is easier to follow: Reviewed-by: Brian Foster <bfoster@redhat.com> > + list_del_init(&dfc->dfc_list); > + xfs_defer_ops_continue(dfc, tp); > + > + error = xfs_trans_commit(tp); > + if (error) > + return error; > + } > + > + ASSERT(list_empty(capture_list)); > + return 0; > } > > +/* Release all the captured defer ops and capture structures in this list. */ > +static void > +xlog_abort_defer_ops( > + struct xfs_mount *mp, > + struct list_head *capture_list) > +{ > + struct xfs_defer_capture *dfc; > + struct xfs_defer_capture *next; > + > + list_for_each_entry_safe(dfc, next, capture_list, dfc_list) { > + list_del_init(&dfc->dfc_list); > + xfs_defer_ops_release(mp, dfc); > + } > +} > /* > * When this is called, all of the log intent items which did not have > * corresponding log done items should be in the AIL. What we do now > @@ -2485,35 +2510,23 @@ STATIC int > xlog_recover_process_intents( > struct xlog *log) > { > - struct xfs_trans *parent_tp; > + LIST_HEAD(capture_list); > struct xfs_ail_cursor cur; > struct xfs_log_item *lip; > struct xfs_ail *ailp; > - int error; > + int error = 0; > #if defined(DEBUG) || defined(XFS_WARN) > xfs_lsn_t last_lsn; > #endif > > - /* > - * The intent recovery handlers commit transactions to complete recovery > - * for individual intents, but any new deferred operations that are > - * queued during that process are held off until the very end. The > - * purpose of this transaction is to serve as a container for deferred > - * operations. Each intent recovery handler must transfer dfops here > - * before its local transaction commits, and we'll finish the entire > - * list below. > - */ > - error = xfs_trans_alloc_empty(log->l_mp, &parent_tp); > - if (error) > - return error; > - > ailp = log->l_ailp; > spin_lock(&ailp->ail_lock); > - lip = xfs_trans_ail_cursor_first(ailp, &cur, 0); > #if defined(DEBUG) || defined(XFS_WARN) > last_lsn = xlog_assign_lsn(log->l_curr_cycle, log->l_curr_block); > #endif > - while (lip != NULL) { > + for (lip = xfs_trans_ail_cursor_first(ailp, &cur, 0); > + lip != NULL; > + lip = xfs_trans_ail_cursor_next(ailp, &cur)) { > /* > * We're done when we see something other than an intent. > * There should be no intents left in the AIL now. > @@ -2535,24 +2548,29 @@ xlog_recover_process_intents( > > /* > * NOTE: If your intent processing routine can create more > - * deferred ops, you /must/ attach them to the transaction in > - * this routine or else those subsequent intents will get > + * deferred ops, you /must/ attach them to the capture list in > + * the recover routine or else those subsequent intents will be > * replayed in the wrong order! > */ > spin_unlock(&ailp->ail_lock); > - error = lip->li_ops->iop_recover(lip, parent_tp); > + error = lip->li_ops->iop_recover(lip, &capture_list); > spin_lock(&ailp->ail_lock); > if (error) > - goto out; > - lip = xfs_trans_ail_cursor_next(ailp, &cur); > + break; > } > -out: > + > xfs_trans_ail_cursor_done(&cur); > spin_unlock(&ailp->ail_lock); > - if (!error) > - error = xlog_finish_defer_ops(parent_tp); > - xfs_trans_cancel(parent_tp); > + if (error) > + goto err; > > + error = xlog_finish_defer_ops(log->l_mp, &capture_list); > + if (error) > + goto err; > + > + return 0; > +err: > + xlog_abort_defer_ops(log->l_mp, &capture_list); > return error; > } > > diff --git a/fs/xfs/xfs_refcount_item.c b/fs/xfs/xfs_refcount_item.c > index 3e34b7662361..0478374add64 100644 > --- a/fs/xfs/xfs_refcount_item.c > +++ b/fs/xfs/xfs_refcount_item.c > @@ -424,7 +424,7 @@ const struct xfs_defer_op_type xfs_refcount_update_defer_type = { > STATIC int > xfs_cui_item_recover( > struct xfs_log_item *lip, > - struct xfs_trans *parent_tp) > + struct list_head *capture_list) > { > struct xfs_bmbt_irec irec; > struct xfs_cui_log_item *cuip = CUI_ITEM(lip); > @@ -432,7 +432,7 @@ xfs_cui_item_recover( > struct xfs_cud_log_item *cudp; > struct xfs_trans *tp; > struct xfs_btree_cur *rcur = NULL; > - struct xfs_mount *mp = parent_tp->t_mountp; > + struct xfs_mount *mp = lip->li_mountp; > xfs_fsblock_t startblock_fsb; > xfs_fsblock_t new_fsb; > xfs_extlen_t new_len; > @@ -487,12 +487,7 @@ xfs_cui_item_recover( > mp->m_refc_maxlevels * 2, 0, XFS_TRANS_RESERVE, &tp); > if (error) > return error; > - /* > - * Recovery stashes all deferred ops during intent processing and > - * finishes them on completion. Transfer current dfops state to this > - * transaction and transfer the result back before we return. > - */ > - xfs_defer_move(tp, parent_tp); > + > cudp = xfs_trans_get_cud(tp, cuip); > > for (i = 0; i < cuip->cui_format.cui_nextents; i++) { > @@ -549,13 +544,10 @@ xfs_cui_item_recover( > } > > xfs_refcount_finish_one_cleanup(tp, rcur, error); > - xfs_defer_capture(parent_tp, tp); > - error = xfs_trans_commit(tp); > - return error; > + return xfs_defer_ops_capture_and_commit(tp, capture_list); > > abort_error: > xfs_refcount_finish_one_cleanup(tp, rcur, error); > - xfs_defer_move(parent_tp, tp); > xfs_trans_cancel(tp); > return error; > } > diff --git a/fs/xfs/xfs_rmap_item.c b/fs/xfs/xfs_rmap_item.c > index e38ec5d736be..0d8fa707f079 100644 > --- a/fs/xfs/xfs_rmap_item.c > +++ b/fs/xfs/xfs_rmap_item.c > @@ -467,14 +467,14 @@ const struct xfs_defer_op_type xfs_rmap_update_defer_type = { > STATIC int > xfs_rui_item_recover( > struct xfs_log_item *lip, > - struct xfs_trans *parent_tp) > + struct list_head *capture_list) > { > struct xfs_rui_log_item *ruip = RUI_ITEM(lip); > struct xfs_map_extent *rmap; > struct xfs_rud_log_item *rudp; > struct xfs_trans *tp; > struct xfs_btree_cur *rcur = NULL; > - struct xfs_mount *mp = parent_tp->t_mountp; > + struct xfs_mount *mp = lip->li_mountp; > xfs_fsblock_t startblock_fsb; > enum xfs_rmap_intent_type type; > xfs_exntst_t state; > @@ -567,8 +567,7 @@ xfs_rui_item_recover( > } > > xfs_rmap_finish_one_cleanup(tp, rcur, error); > - error = xfs_trans_commit(tp); > - return error; > + return xfs_defer_ops_capture_and_commit(tp, capture_list); > > abort_error: > xfs_rmap_finish_one_cleanup(tp, rcur, error); > diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h > index ced62a35a62b..186e77d08cc1 100644 > --- a/fs/xfs/xfs_trans.h > +++ b/fs/xfs/xfs_trans.h > @@ -72,7 +72,8 @@ struct xfs_item_ops { > void (*iop_committing)(struct xfs_log_item *, xfs_lsn_t commit_lsn); > void (*iop_release)(struct xfs_log_item *); > xfs_lsn_t (*iop_committed)(struct xfs_log_item *, xfs_lsn_t); > - int (*iop_recover)(struct xfs_log_item *lip, struct xfs_trans *tp); > + int (*iop_recover)(struct xfs_log_item *lip, > + struct list_head *capture_list); > bool (*iop_match)(struct xfs_log_item *item, uint64_t id); > }; > >
On Thu, Oct 01, 2020 at 01:31:42PM -0400, Brian Foster wrote: > On Tue, Sep 29, 2020 at 10:43:31AM -0700, Darrick J. Wong wrote: > > From: Darrick J. Wong <darrick.wong@oracle.com> > > > > When we replay unfinished intent items that have been recovered from the > > log, it's possible that the replay will cause the creation of more > > deferred work items. As outlined in commit 509955823cc9c ("xfs: log > > recovery should replay deferred ops in order"), later work items have an > > implicit ordering dependency on earlier work items. Therefore, recovery > > must replay the items (both recovered and created) in the same order > > that they would have been during normal operation. > > > > For log recovery, we enforce this ordering by using an empty transaction > > to collect deferred ops that get created in the process of recovering a > > log intent item to prevent them from being committed before the rest of > > the recovered intent items. After we finish committing all the > > recovered log items, we allocate a transaction with an enormous block > > reservation, splice our huge list of created deferred ops into that > > transaction, and commit it, thereby finishing all those ops. > > > > This is /really/ hokey -- it's the one place in XFS where we allow > > nested transactions; the splicing of the defer ops list is is inelegant > > and has to be done twice per recovery function; and the broken way we > > handle inode pointers and block reservations cause subtle use-after-free > > and allocator problems that will be fixed by this patch and the two > > patches after it. > > > > Therefore, replace the hokey empty transaction with a structure designed > > to capture each chain of deferred ops that are created as part of > > recovering a single unfinished log intent. Finally, refactor the loop > > that replays those chains to do so using one transaction per chain. > > > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> > > --- > > fs/xfs/libxfs/xfs_defer.c | 89 +++++++++++++++++++++++++++++++-- > > fs/xfs/libxfs/xfs_defer.h | 19 +++++++ > > fs/xfs/xfs_bmap_item.c | 16 +----- > > fs/xfs/xfs_extfree_item.c | 7 +-- > > fs/xfs/xfs_log_recover.c | 118 +++++++++++++++++++++++++------------------- > > fs/xfs/xfs_refcount_item.c | 16 +----- > > fs/xfs/xfs_rmap_item.c | 7 +-- > > fs/xfs/xfs_trans.h | 3 + > > 8 files changed, 184 insertions(+), 91 deletions(-) > > > > > ... > > diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c > > index 84f876c6d498..550d0fa8057a 100644 > > --- a/fs/xfs/xfs_log_recover.c > > +++ b/fs/xfs/xfs_log_recover.c > > @@ -2434,37 +2434,62 @@ xlog_recover_process_data( > > /* Take all the collected deferred ops and finish them in order. */ > > static int > > xlog_finish_defer_ops( > > - struct xfs_trans *parent_tp) > > + struct xfs_mount *mp, > > + struct list_head *capture_list) > > { > > - struct xfs_mount *mp = parent_tp->t_mountp; > > + struct xfs_defer_capture *dfc, *next; > > struct xfs_trans *tp; > > int64_t freeblks; > > - uint resblks; > > - int error; > > + uint64_t resblks; > > + int error = 0; > > > > - /* > > - * We're finishing the defer_ops that accumulated as a result of > > - * recovering unfinished intent items during log recovery. We > > - * reserve an itruncate transaction because it is the largest > > - * permanent transaction type. Since we're the only user of the fs > > - * right now, take 93% (15/16) of the available free blocks. Use > > - * weird math to avoid a 64-bit division. > > - */ > > - freeblks = percpu_counter_sum(&mp->m_fdblocks); > > - if (freeblks <= 0) > > - return -ENOSPC; > > - resblks = min_t(int64_t, UINT_MAX, freeblks); > > - resblks = (resblks * 15) >> 4; > > - error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, resblks, > > - 0, XFS_TRANS_RESERVE, &tp); > > - if (error) > > - return error; > > - /* transfer all collected dfops to this transaction */ > > - xfs_defer_move(tp, parent_tp); > > + list_for_each_entry_safe(dfc, next, capture_list, dfc_list) { > > + /* > > + * We're finishing the defer_ops that accumulated as a result > > + * of recovering unfinished intent items during log recovery. > > + * We reserve an itruncate transaction because it is the > > + * largest permanent transaction type. Since we're the only > > + * user of the fs right now, take 93% (15/16) of the available > > + * free blocks. Use weird math to avoid a 64-bit division. > > + */ > > + freeblks = percpu_counter_sum(&mp->m_fdblocks); > > + if (freeblks <= 0) > > + return -ENOSPC; > > > > - return xfs_trans_commit(tp); > > + resblks = min_t(uint64_t, UINT_MAX, freeblks); > > + resblks = (resblks * 15) >> 4; > > + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, resblks, > > + 0, XFS_TRANS_RESERVE, &tp); > > + if (error) > > + return error; > > + > > + /* Transfer all collected dfops to this transaction. */ > > This old comment is a little misleading now that we have per-intent > capture lists. That nit aside, this looks good to me and the updated > factoring is easier to follow: I'll change it to: /* * Transfer to this new transaction all the dfops we captured * from recovering a single intent item. */ > Reviewed-by: Brian Foster <bfoster@redhat.com> Thanks for the review! --D > > > + list_del_init(&dfc->dfc_list); > > + xfs_defer_ops_continue(dfc, tp); > > + > > + error = xfs_trans_commit(tp); > > + if (error) > > + return error; > > + } > > + > > + ASSERT(list_empty(capture_list)); > > + return 0; > > } > > > > +/* Release all the captured defer ops and capture structures in this list. */ > > +static void > > +xlog_abort_defer_ops( > > + struct xfs_mount *mp, > > + struct list_head *capture_list) > > +{ > > + struct xfs_defer_capture *dfc; > > + struct xfs_defer_capture *next; > > + > > + list_for_each_entry_safe(dfc, next, capture_list, dfc_list) { > > + list_del_init(&dfc->dfc_list); > > + xfs_defer_ops_release(mp, dfc); > > + } > > +} > > /* > > * When this is called, all of the log intent items which did not have > > * corresponding log done items should be in the AIL. What we do now > > @@ -2485,35 +2510,23 @@ STATIC int > > xlog_recover_process_intents( > > struct xlog *log) > > { > > - struct xfs_trans *parent_tp; > > + LIST_HEAD(capture_list); > > struct xfs_ail_cursor cur; > > struct xfs_log_item *lip; > > struct xfs_ail *ailp; > > - int error; > > + int error = 0; > > #if defined(DEBUG) || defined(XFS_WARN) > > xfs_lsn_t last_lsn; > > #endif > > > > - /* > > - * The intent recovery handlers commit transactions to complete recovery > > - * for individual intents, but any new deferred operations that are > > - * queued during that process are held off until the very end. The > > - * purpose of this transaction is to serve as a container for deferred > > - * operations. Each intent recovery handler must transfer dfops here > > - * before its local transaction commits, and we'll finish the entire > > - * list below. > > - */ > > - error = xfs_trans_alloc_empty(log->l_mp, &parent_tp); > > - if (error) > > - return error; > > - > > ailp = log->l_ailp; > > spin_lock(&ailp->ail_lock); > > - lip = xfs_trans_ail_cursor_first(ailp, &cur, 0); > > #if defined(DEBUG) || defined(XFS_WARN) > > last_lsn = xlog_assign_lsn(log->l_curr_cycle, log->l_curr_block); > > #endif > > - while (lip != NULL) { > > + for (lip = xfs_trans_ail_cursor_first(ailp, &cur, 0); > > + lip != NULL; > > + lip = xfs_trans_ail_cursor_next(ailp, &cur)) { > > /* > > * We're done when we see something other than an intent. > > * There should be no intents left in the AIL now. > > @@ -2535,24 +2548,29 @@ xlog_recover_process_intents( > > > > /* > > * NOTE: If your intent processing routine can create more > > - * deferred ops, you /must/ attach them to the transaction in > > - * this routine or else those subsequent intents will get > > + * deferred ops, you /must/ attach them to the capture list in > > + * the recover routine or else those subsequent intents will be > > * replayed in the wrong order! > > */ > > spin_unlock(&ailp->ail_lock); > > - error = lip->li_ops->iop_recover(lip, parent_tp); > > + error = lip->li_ops->iop_recover(lip, &capture_list); > > spin_lock(&ailp->ail_lock); > > if (error) > > - goto out; > > - lip = xfs_trans_ail_cursor_next(ailp, &cur); > > + break; > > } > > -out: > > + > > xfs_trans_ail_cursor_done(&cur); > > spin_unlock(&ailp->ail_lock); > > - if (!error) > > - error = xlog_finish_defer_ops(parent_tp); > > - xfs_trans_cancel(parent_tp); > > + if (error) > > + goto err; > > > > + error = xlog_finish_defer_ops(log->l_mp, &capture_list); > > + if (error) > > + goto err; > > + > > + return 0; > > +err: > > + xlog_abort_defer_ops(log->l_mp, &capture_list); > > return error; > > } > > > > diff --git a/fs/xfs/xfs_refcount_item.c b/fs/xfs/xfs_refcount_item.c > > index 3e34b7662361..0478374add64 100644 > > --- a/fs/xfs/xfs_refcount_item.c > > +++ b/fs/xfs/xfs_refcount_item.c > > @@ -424,7 +424,7 @@ const struct xfs_defer_op_type xfs_refcount_update_defer_type = { > > STATIC int > > xfs_cui_item_recover( > > struct xfs_log_item *lip, > > - struct xfs_trans *parent_tp) > > + struct list_head *capture_list) > > { > > struct xfs_bmbt_irec irec; > > struct xfs_cui_log_item *cuip = CUI_ITEM(lip); > > @@ -432,7 +432,7 @@ xfs_cui_item_recover( > > struct xfs_cud_log_item *cudp; > > struct xfs_trans *tp; > > struct xfs_btree_cur *rcur = NULL; > > - struct xfs_mount *mp = parent_tp->t_mountp; > > + struct xfs_mount *mp = lip->li_mountp; > > xfs_fsblock_t startblock_fsb; > > xfs_fsblock_t new_fsb; > > xfs_extlen_t new_len; > > @@ -487,12 +487,7 @@ xfs_cui_item_recover( > > mp->m_refc_maxlevels * 2, 0, XFS_TRANS_RESERVE, &tp); > > if (error) > > return error; > > - /* > > - * Recovery stashes all deferred ops during intent processing and > > - * finishes them on completion. Transfer current dfops state to this > > - * transaction and transfer the result back before we return. > > - */ > > - xfs_defer_move(tp, parent_tp); > > + > > cudp = xfs_trans_get_cud(tp, cuip); > > > > for (i = 0; i < cuip->cui_format.cui_nextents; i++) { > > @@ -549,13 +544,10 @@ xfs_cui_item_recover( > > } > > > > xfs_refcount_finish_one_cleanup(tp, rcur, error); > > - xfs_defer_capture(parent_tp, tp); > > - error = xfs_trans_commit(tp); > > - return error; > > + return xfs_defer_ops_capture_and_commit(tp, capture_list); > > > > abort_error: > > xfs_refcount_finish_one_cleanup(tp, rcur, error); > > - xfs_defer_move(parent_tp, tp); > > xfs_trans_cancel(tp); > > return error; > > } > > diff --git a/fs/xfs/xfs_rmap_item.c b/fs/xfs/xfs_rmap_item.c > > index e38ec5d736be..0d8fa707f079 100644 > > --- a/fs/xfs/xfs_rmap_item.c > > +++ b/fs/xfs/xfs_rmap_item.c > > @@ -467,14 +467,14 @@ const struct xfs_defer_op_type xfs_rmap_update_defer_type = { > > STATIC int > > xfs_rui_item_recover( > > struct xfs_log_item *lip, > > - struct xfs_trans *parent_tp) > > + struct list_head *capture_list) > > { > > struct xfs_rui_log_item *ruip = RUI_ITEM(lip); > > struct xfs_map_extent *rmap; > > struct xfs_rud_log_item *rudp; > > struct xfs_trans *tp; > > struct xfs_btree_cur *rcur = NULL; > > - struct xfs_mount *mp = parent_tp->t_mountp; > > + struct xfs_mount *mp = lip->li_mountp; > > xfs_fsblock_t startblock_fsb; > > enum xfs_rmap_intent_type type; > > xfs_exntst_t state; > > @@ -567,8 +567,7 @@ xfs_rui_item_recover( > > } > > > > xfs_rmap_finish_one_cleanup(tp, rcur, error); > > - error = xfs_trans_commit(tp); > > - return error; > > + return xfs_defer_ops_capture_and_commit(tp, capture_list); > > > > abort_error: > > xfs_rmap_finish_one_cleanup(tp, rcur, error); > > diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h > > index ced62a35a62b..186e77d08cc1 100644 > > --- a/fs/xfs/xfs_trans.h > > +++ b/fs/xfs/xfs_trans.h > > @@ -72,7 +72,8 @@ struct xfs_item_ops { > > void (*iop_committing)(struct xfs_log_item *, xfs_lsn_t commit_lsn); > > void (*iop_release)(struct xfs_log_item *); > > xfs_lsn_t (*iop_committed)(struct xfs_log_item *, xfs_lsn_t); > > - int (*iop_recover)(struct xfs_log_item *lip, struct xfs_trans *tp); > > + int (*iop_recover)(struct xfs_log_item *lip, > > + struct list_head *capture_list); > > bool (*iop_match)(struct xfs_log_item *item, uint64_t id); > > }; > > > > >
On Tue, Sep 29, 2020 at 10:43:31AM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong <darrick.wong@oracle.com> > > When we replay unfinished intent items that have been recovered from the > log, it's possible that the replay will cause the creation of more > deferred work items. As outlined in commit 509955823cc9c ("xfs: log > recovery should replay deferred ops in order"), later work items have an > implicit ordering dependency on earlier work items. Therefore, recovery > must replay the items (both recovered and created) in the same order > that they would have been during normal operation. > > For log recovery, we enforce this ordering by using an empty transaction > to collect deferred ops that get created in the process of recovering a > log intent item to prevent them from being committed before the rest of > the recovered intent items. After we finish committing all the > recovered log items, we allocate a transaction with an enormous block > reservation, splice our huge list of created deferred ops into that > transaction, and commit it, thereby finishing all those ops. > > This is /really/ hokey -- it's the one place in XFS where we allow > nested transactions; the splicing of the defer ops list is is inelegant > and has to be done twice per recovery function; and the broken way we > handle inode pointers and block reservations cause subtle use-after-free > and allocator problems that will be fixed by this patch and the two > patches after it. > > Therefore, replace the hokey empty transaction with a structure designed > to capture each chain of deferred ops that are created as part of > recovering a single unfinished log intent. Finally, refactor the loop > that replays those chains to do so using one transaction per chain. > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> > --- > fs/xfs/libxfs/xfs_defer.c | 89 +++++++++++++++++++++++++++++++-- > fs/xfs/libxfs/xfs_defer.h | 19 +++++++ > fs/xfs/xfs_bmap_item.c | 16 +----- > fs/xfs/xfs_extfree_item.c | 7 +-- > fs/xfs/xfs_log_recover.c | 118 +++++++++++++++++++++++++------------------- > fs/xfs/xfs_refcount_item.c | 16 +----- > fs/xfs/xfs_rmap_item.c | 7 +-- > fs/xfs/xfs_trans.h | 3 + > 8 files changed, 184 insertions(+), 91 deletions(-) > > > diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c > index 36c103c14bc9..85c371d29e8d 100644 > --- a/fs/xfs/libxfs/xfs_defer.c > +++ b/fs/xfs/libxfs/xfs_defer.c > @@ -549,14 +549,89 @@ xfs_defer_move( > * > * Create and log intent items for all the work that we're capturing so that we > * can be assured that the items will get replayed if the system goes down > - * before log recovery gets a chance to finish the work it put off. Then we > - * move the chain from stp to dtp. > + * before log recovery gets a chance to finish the work it put off. The entire > + * deferred ops state is transferred to the capture structure and the > + * transaction is then ready for the caller to commit it. If there are no > + * intent items to capture, this function returns NULL. > + */ > +static struct xfs_defer_capture * > +xfs_defer_ops_capture( > + struct xfs_trans *tp) > +{ > + struct xfs_defer_capture *dfc; > + > + if (list_empty(&tp->t_dfops)) > + return NULL; Nit: keeping the list_empty check in the caller would seems more obvious to me. Otherwise looks good: Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c index 36c103c14bc9..85c371d29e8d 100644 --- a/fs/xfs/libxfs/xfs_defer.c +++ b/fs/xfs/libxfs/xfs_defer.c @@ -549,14 +549,89 @@ xfs_defer_move( * * Create and log intent items for all the work that we're capturing so that we * can be assured that the items will get replayed if the system goes down - * before log recovery gets a chance to finish the work it put off. Then we - * move the chain from stp to dtp. + * before log recovery gets a chance to finish the work it put off. The entire + * deferred ops state is transferred to the capture structure and the + * transaction is then ready for the caller to commit it. If there are no + * intent items to capture, this function returns NULL. + */ +static struct xfs_defer_capture * +xfs_defer_ops_capture( + struct xfs_trans *tp) +{ + struct xfs_defer_capture *dfc; + + if (list_empty(&tp->t_dfops)) + return NULL; + + /* Create an object to capture the defer ops. */ + dfc = kmem_zalloc(sizeof(*dfc), KM_NOFS); + INIT_LIST_HEAD(&dfc->dfc_list); + INIT_LIST_HEAD(&dfc->dfc_dfops); + + xfs_defer_create_intents(tp); + + /* Move the dfops chain and transaction state to the capture struct. */ + list_splice_init(&tp->t_dfops, &dfc->dfc_dfops); + dfc->dfc_tpflags = tp->t_flags & XFS_TRANS_LOWMODE; + tp->t_flags &= ~XFS_TRANS_LOWMODE; + + return dfc; +} + +/* Release all resources that we used to capture deferred ops. */ +void +xfs_defer_ops_release( + struct xfs_mount *mp, + struct xfs_defer_capture *dfc) +{ + xfs_defer_cancel_list(mp, &dfc->dfc_dfops); + kmem_free(dfc); +} + +/* + * Capture any deferred ops and commit the transaction. This is the last step + * needed to finish a log intent item that we recovered from the log. + */ +int +xfs_defer_ops_capture_and_commit( + struct xfs_trans *tp, + struct list_head *capture_list) +{ + struct xfs_mount *mp = tp->t_mountp; + struct xfs_defer_capture *dfc; + int error; + + /* If we don't capture anything, commit transaction and exit. */ + dfc = xfs_defer_ops_capture(tp); + if (!dfc) + return xfs_trans_commit(tp); + + /* Commit the transaction and add the capture structure to the list. */ + error = xfs_trans_commit(tp); + if (error) { + xfs_defer_ops_release(mp, dfc); + return error; + } + + list_add_tail(&dfc->dfc_list, capture_list); + return 0; +} + +/* + * Attach a chain of captured deferred ops to a new transaction and free the + * capture structure. */ void -xfs_defer_capture( - struct xfs_trans *dtp, - struct xfs_trans *stp) +xfs_defer_ops_continue( + struct xfs_defer_capture *dfc, + struct xfs_trans *tp) { - xfs_defer_create_intents(stp); - xfs_defer_move(dtp, stp); + ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES); + ASSERT(!(tp->t_flags & XFS_TRANS_DIRTY)); + + /* Move captured dfops chain and state to the transaction. */ + list_splice_init(&dfc->dfc_dfops, &tp->t_dfops); + tp->t_flags |= dfc->dfc_tpflags; + + kmem_free(dfc); } diff --git a/fs/xfs/libxfs/xfs_defer.h b/fs/xfs/libxfs/xfs_defer.h index 3164199162b6..3af82ebc1249 100644 --- a/fs/xfs/libxfs/xfs_defer.h +++ b/fs/xfs/libxfs/xfs_defer.h @@ -8,6 +8,7 @@ struct xfs_btree_cur; struct xfs_defer_op_type; +struct xfs_defer_capture; /* * Header for deferred operation list. @@ -63,10 +64,26 @@ extern const struct xfs_defer_op_type xfs_rmap_update_defer_type; extern const struct xfs_defer_op_type xfs_extent_free_defer_type; extern const struct xfs_defer_op_type xfs_agfl_free_defer_type; +/* + * This structure enables a dfops user to detach the chain of deferred + * operations from a transaction so that they can be continued later. + */ +struct xfs_defer_capture { + /* List of other capture structures. */ + struct list_head dfc_list; + + /* Deferred ops state saved from the transaction. */ + struct list_head dfc_dfops; + unsigned int dfc_tpflags; +}; + /* * Functions to capture a chain of deferred operations and continue them later. * This doesn't normally happen except log recovery. */ -void xfs_defer_capture(struct xfs_trans *dtp, struct xfs_trans *stp); +int xfs_defer_ops_capture_and_commit(struct xfs_trans *tp, + struct list_head *capture_list); +void xfs_defer_ops_continue(struct xfs_defer_capture *d, struct xfs_trans *tp); +void xfs_defer_ops_release(struct xfs_mount *mp, struct xfs_defer_capture *d); #endif /* __XFS_DEFER_H__ */ diff --git a/fs/xfs/xfs_bmap_item.c b/fs/xfs/xfs_bmap_item.c index b04ebcd78316..126df48dae5f 100644 --- a/fs/xfs/xfs_bmap_item.c +++ b/fs/xfs/xfs_bmap_item.c @@ -424,13 +424,13 @@ const struct xfs_defer_op_type xfs_bmap_update_defer_type = { STATIC int xfs_bui_item_recover( struct xfs_log_item *lip, - struct xfs_trans *parent_tp) + struct list_head *capture_list) { struct xfs_bmbt_irec irec; struct xfs_bui_log_item *buip = BUI_ITEM(lip); struct xfs_trans *tp; struct xfs_inode *ip = NULL; - struct xfs_mount *mp = parent_tp->t_mountp; + struct xfs_mount *mp = lip->li_mountp; struct xfs_map_extent *bmap; struct xfs_bud_log_item *budp; xfs_fsblock_t startblock_fsb; @@ -478,12 +478,7 @@ xfs_bui_item_recover( XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK), 0, 0, &tp); if (error) return error; - /* - * Recovery stashes all deferred ops during intent processing and - * finishes them on completion. Transfer current dfops state to this - * transaction and transfer the result back before we return. - */ - xfs_defer_move(tp, parent_tp); + budp = xfs_trans_get_bud(tp, buip); /* Grab the inode. */ @@ -531,15 +526,12 @@ xfs_bui_item_recover( xfs_bmap_unmap_extent(tp, ip, &irec); } - xfs_defer_capture(parent_tp, tp); - error = xfs_trans_commit(tp); + error = xfs_defer_ops_capture_and_commit(tp, capture_list); xfs_iunlock(ip, XFS_ILOCK_EXCL); xfs_irele(ip); - return error; err_inode: - xfs_defer_move(parent_tp, tp); xfs_trans_cancel(tp); if (ip) { xfs_iunlock(ip, XFS_ILOCK_EXCL); diff --git a/fs/xfs/xfs_extfree_item.c b/fs/xfs/xfs_extfree_item.c index 9093d2e7afdf..17d36fe5cfd0 100644 --- a/fs/xfs/xfs_extfree_item.c +++ b/fs/xfs/xfs_extfree_item.c @@ -585,10 +585,10 @@ const struct xfs_defer_op_type xfs_agfl_free_defer_type = { STATIC int xfs_efi_item_recover( struct xfs_log_item *lip, - struct xfs_trans *parent_tp) + struct list_head *capture_list) { struct xfs_efi_log_item *efip = EFI_ITEM(lip); - struct xfs_mount *mp = parent_tp->t_mountp; + struct xfs_mount *mp = lip->li_mountp; struct xfs_efd_log_item *efdp; struct xfs_trans *tp; struct xfs_extent *extp; @@ -627,8 +627,7 @@ xfs_efi_item_recover( } - error = xfs_trans_commit(tp); - return error; + return xfs_defer_ops_capture_and_commit(tp, capture_list); abort_error: xfs_trans_cancel(tp); diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c index 84f876c6d498..550d0fa8057a 100644 --- a/fs/xfs/xfs_log_recover.c +++ b/fs/xfs/xfs_log_recover.c @@ -2434,37 +2434,62 @@ xlog_recover_process_data( /* Take all the collected deferred ops and finish them in order. */ static int xlog_finish_defer_ops( - struct xfs_trans *parent_tp) + struct xfs_mount *mp, + struct list_head *capture_list) { - struct xfs_mount *mp = parent_tp->t_mountp; + struct xfs_defer_capture *dfc, *next; struct xfs_trans *tp; int64_t freeblks; - uint resblks; - int error; + uint64_t resblks; + int error = 0; - /* - * We're finishing the defer_ops that accumulated as a result of - * recovering unfinished intent items during log recovery. We - * reserve an itruncate transaction because it is the largest - * permanent transaction type. Since we're the only user of the fs - * right now, take 93% (15/16) of the available free blocks. Use - * weird math to avoid a 64-bit division. - */ - freeblks = percpu_counter_sum(&mp->m_fdblocks); - if (freeblks <= 0) - return -ENOSPC; - resblks = min_t(int64_t, UINT_MAX, freeblks); - resblks = (resblks * 15) >> 4; - error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, resblks, - 0, XFS_TRANS_RESERVE, &tp); - if (error) - return error; - /* transfer all collected dfops to this transaction */ - xfs_defer_move(tp, parent_tp); + list_for_each_entry_safe(dfc, next, capture_list, dfc_list) { + /* + * We're finishing the defer_ops that accumulated as a result + * of recovering unfinished intent items during log recovery. + * We reserve an itruncate transaction because it is the + * largest permanent transaction type. Since we're the only + * user of the fs right now, take 93% (15/16) of the available + * free blocks. Use weird math to avoid a 64-bit division. + */ + freeblks = percpu_counter_sum(&mp->m_fdblocks); + if (freeblks <= 0) + return -ENOSPC; - return xfs_trans_commit(tp); + resblks = min_t(uint64_t, UINT_MAX, freeblks); + resblks = (resblks * 15) >> 4; + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, resblks, + 0, XFS_TRANS_RESERVE, &tp); + if (error) + return error; + + /* Transfer all collected dfops to this transaction. */ + list_del_init(&dfc->dfc_list); + xfs_defer_ops_continue(dfc, tp); + + error = xfs_trans_commit(tp); + if (error) + return error; + } + + ASSERT(list_empty(capture_list)); + return 0; } +/* Release all the captured defer ops and capture structures in this list. */ +static void +xlog_abort_defer_ops( + struct xfs_mount *mp, + struct list_head *capture_list) +{ + struct xfs_defer_capture *dfc; + struct xfs_defer_capture *next; + + list_for_each_entry_safe(dfc, next, capture_list, dfc_list) { + list_del_init(&dfc->dfc_list); + xfs_defer_ops_release(mp, dfc); + } +} /* * When this is called, all of the log intent items which did not have * corresponding log done items should be in the AIL. What we do now @@ -2485,35 +2510,23 @@ STATIC int xlog_recover_process_intents( struct xlog *log) { - struct xfs_trans *parent_tp; + LIST_HEAD(capture_list); struct xfs_ail_cursor cur; struct xfs_log_item *lip; struct xfs_ail *ailp; - int error; + int error = 0; #if defined(DEBUG) || defined(XFS_WARN) xfs_lsn_t last_lsn; #endif - /* - * The intent recovery handlers commit transactions to complete recovery - * for individual intents, but any new deferred operations that are - * queued during that process are held off until the very end. The - * purpose of this transaction is to serve as a container for deferred - * operations. Each intent recovery handler must transfer dfops here - * before its local transaction commits, and we'll finish the entire - * list below. - */ - error = xfs_trans_alloc_empty(log->l_mp, &parent_tp); - if (error) - return error; - ailp = log->l_ailp; spin_lock(&ailp->ail_lock); - lip = xfs_trans_ail_cursor_first(ailp, &cur, 0); #if defined(DEBUG) || defined(XFS_WARN) last_lsn = xlog_assign_lsn(log->l_curr_cycle, log->l_curr_block); #endif - while (lip != NULL) { + for (lip = xfs_trans_ail_cursor_first(ailp, &cur, 0); + lip != NULL; + lip = xfs_trans_ail_cursor_next(ailp, &cur)) { /* * We're done when we see something other than an intent. * There should be no intents left in the AIL now. @@ -2535,24 +2548,29 @@ xlog_recover_process_intents( /* * NOTE: If your intent processing routine can create more - * deferred ops, you /must/ attach them to the transaction in - * this routine or else those subsequent intents will get + * deferred ops, you /must/ attach them to the capture list in + * the recover routine or else those subsequent intents will be * replayed in the wrong order! */ spin_unlock(&ailp->ail_lock); - error = lip->li_ops->iop_recover(lip, parent_tp); + error = lip->li_ops->iop_recover(lip, &capture_list); spin_lock(&ailp->ail_lock); if (error) - goto out; - lip = xfs_trans_ail_cursor_next(ailp, &cur); + break; } -out: + xfs_trans_ail_cursor_done(&cur); spin_unlock(&ailp->ail_lock); - if (!error) - error = xlog_finish_defer_ops(parent_tp); - xfs_trans_cancel(parent_tp); + if (error) + goto err; + error = xlog_finish_defer_ops(log->l_mp, &capture_list); + if (error) + goto err; + + return 0; +err: + xlog_abort_defer_ops(log->l_mp, &capture_list); return error; } diff --git a/fs/xfs/xfs_refcount_item.c b/fs/xfs/xfs_refcount_item.c index 3e34b7662361..0478374add64 100644 --- a/fs/xfs/xfs_refcount_item.c +++ b/fs/xfs/xfs_refcount_item.c @@ -424,7 +424,7 @@ const struct xfs_defer_op_type xfs_refcount_update_defer_type = { STATIC int xfs_cui_item_recover( struct xfs_log_item *lip, - struct xfs_trans *parent_tp) + struct list_head *capture_list) { struct xfs_bmbt_irec irec; struct xfs_cui_log_item *cuip = CUI_ITEM(lip); @@ -432,7 +432,7 @@ xfs_cui_item_recover( struct xfs_cud_log_item *cudp; struct xfs_trans *tp; struct xfs_btree_cur *rcur = NULL; - struct xfs_mount *mp = parent_tp->t_mountp; + struct xfs_mount *mp = lip->li_mountp; xfs_fsblock_t startblock_fsb; xfs_fsblock_t new_fsb; xfs_extlen_t new_len; @@ -487,12 +487,7 @@ xfs_cui_item_recover( mp->m_refc_maxlevels * 2, 0, XFS_TRANS_RESERVE, &tp); if (error) return error; - /* - * Recovery stashes all deferred ops during intent processing and - * finishes them on completion. Transfer current dfops state to this - * transaction and transfer the result back before we return. - */ - xfs_defer_move(tp, parent_tp); + cudp = xfs_trans_get_cud(tp, cuip); for (i = 0; i < cuip->cui_format.cui_nextents; i++) { @@ -549,13 +544,10 @@ xfs_cui_item_recover( } xfs_refcount_finish_one_cleanup(tp, rcur, error); - xfs_defer_capture(parent_tp, tp); - error = xfs_trans_commit(tp); - return error; + return xfs_defer_ops_capture_and_commit(tp, capture_list); abort_error: xfs_refcount_finish_one_cleanup(tp, rcur, error); - xfs_defer_move(parent_tp, tp); xfs_trans_cancel(tp); return error; } diff --git a/fs/xfs/xfs_rmap_item.c b/fs/xfs/xfs_rmap_item.c index e38ec5d736be..0d8fa707f079 100644 --- a/fs/xfs/xfs_rmap_item.c +++ b/fs/xfs/xfs_rmap_item.c @@ -467,14 +467,14 @@ const struct xfs_defer_op_type xfs_rmap_update_defer_type = { STATIC int xfs_rui_item_recover( struct xfs_log_item *lip, - struct xfs_trans *parent_tp) + struct list_head *capture_list) { struct xfs_rui_log_item *ruip = RUI_ITEM(lip); struct xfs_map_extent *rmap; struct xfs_rud_log_item *rudp; struct xfs_trans *tp; struct xfs_btree_cur *rcur = NULL; - struct xfs_mount *mp = parent_tp->t_mountp; + struct xfs_mount *mp = lip->li_mountp; xfs_fsblock_t startblock_fsb; enum xfs_rmap_intent_type type; xfs_exntst_t state; @@ -567,8 +567,7 @@ xfs_rui_item_recover( } xfs_rmap_finish_one_cleanup(tp, rcur, error); - error = xfs_trans_commit(tp); - return error; + return xfs_defer_ops_capture_and_commit(tp, capture_list); abort_error: xfs_rmap_finish_one_cleanup(tp, rcur, error); diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h index ced62a35a62b..186e77d08cc1 100644 --- a/fs/xfs/xfs_trans.h +++ b/fs/xfs/xfs_trans.h @@ -72,7 +72,8 @@ struct xfs_item_ops { void (*iop_committing)(struct xfs_log_item *, xfs_lsn_t commit_lsn); void (*iop_release)(struct xfs_log_item *); xfs_lsn_t (*iop_committed)(struct xfs_log_item *, xfs_lsn_t); - int (*iop_recover)(struct xfs_log_item *lip, struct xfs_trans *tp); + int (*iop_recover)(struct xfs_log_item *lip, + struct list_head *capture_list); bool (*iop_match)(struct xfs_log_item *item, uint64_t id); };