diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index 0b02c6443551..4184085d44af 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -900,7 +900,7 @@ xfs_log_move_tail(xfs_mount_t *mp, int xfs_log_need_covered(xfs_mount_t *mp) { - int needed = 0, gen; + int needed = 0; xlog_t *log = mp->m_log; if (!xfs_fs_writable(mp)) @@ -909,7 +909,7 @@ xfs_log_need_covered(xfs_mount_t *mp) spin_lock(&log->l_icloglock); if (((log->l_covered_state == XLOG_STATE_COVER_NEED) || (log->l_covered_state == XLOG_STATE_COVER_NEED2)) - && !xfs_trans_first_ail(mp, &gen) + && !xfs_trans_first_ail(mp, NULL) && xlog_iclogs_empty(log)) { if (log->l_covered_state == XLOG_STATE_COVER_NEED) log->l_covered_state = XLOG_STATE_COVER_DONE; diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c index 199c8ea36474..37ba4899f3e6 100644 --- a/fs/xfs/xfs_log_recover.c +++ b/fs/xfs/xfs_log_recover.c @@ -54,10 +54,8 @@ STATIC void xlog_recover_insert_item_backq(xlog_recover_item_t **q, xlog_recover_item_t *item); #if defined(DEBUG) STATIC void xlog_recover_check_summary(xlog_t *); -STATIC void xlog_recover_check_ail(xfs_mount_t *, xfs_log_item_t *, int); #else #define xlog_recover_check_summary(log) -#define xlog_recover_check_ail(mp, lip, gen) #endif @@ -2710,8 +2708,8 @@ xlog_recover_do_efd_trans( xfs_efd_log_format_t *efd_formatp; xfs_efi_log_item_t *efip = NULL; xfs_log_item_t *lip; - int gen; __uint64_t efi_id; + struct xfs_ail_cursor cur; if (pass == XLOG_RECOVER_PASS1) { return; @@ -2730,7 +2728,8 @@ xlog_recover_do_efd_trans( */ mp = log->l_mp; spin_lock(&mp->m_ail_lock); - lip = xfs_trans_first_ail(mp, &gen); + xfs_trans_ail_cursor_init(mp->m_ail, &cur); + lip = xfs_trans_first_ail(mp, &cur); while (lip != NULL) { if (lip->li_type == XFS_LI_EFI) { efip = (xfs_efi_log_item_t *)lip; @@ -2741,11 +2740,13 @@ xlog_recover_do_efd_trans( */ xfs_trans_delete_ail(mp, lip); xfs_efi_item_free(efip); - return; + spin_lock(&mp->m_ail_lock); + break; } } - lip = xfs_trans_next_ail(mp, lip, &gen, NULL); + lip = xfs_trans_next_ail(mp, &cur); } + xfs_trans_ail_cursor_done(mp->m_ail, &cur); spin_unlock(&mp->m_ail_lock); } @@ -3029,33 +3030,6 @@ abort_error: return error; } -/* - * Verify that once we've encountered something other than an EFI - * in the AIL that there are no more EFIs in the AIL. - */ -#if defined(DEBUG) -STATIC void -xlog_recover_check_ail( - xfs_mount_t *mp, - xfs_log_item_t *lip, - int gen) -{ - int orig_gen = gen; - - do { - ASSERT(lip->li_type != XFS_LI_EFI); - lip = xfs_trans_next_ail(mp, lip, &gen, NULL); - /* - * The check will be bogus if we restart from the - * beginning of the AIL, so ASSERT that we don't. - * We never should since we're holding the AIL lock - * the entire time. - */ - ASSERT(gen == orig_gen); - } while (lip != NULL); -} -#endif /* DEBUG */ - /* * When this is called, all of the EFIs which did not have * corresponding EFDs should be in the AIL. What we do now @@ -3080,20 +3054,25 @@ xlog_recover_process_efis( { xfs_log_item_t *lip; xfs_efi_log_item_t *efip; - int gen; xfs_mount_t *mp; int error = 0; + struct xfs_ail_cursor cur; mp = log->l_mp; spin_lock(&mp->m_ail_lock); - lip = xfs_trans_first_ail(mp, &gen); + xfs_trans_ail_cursor_init(mp->m_ail, &cur); + lip = xfs_trans_first_ail(mp, &cur); while (lip != NULL) { /* * We're done when we see something other than an EFI. + * There should be no EFIs left in the AIL now. */ if (lip->li_type != XFS_LI_EFI) { - xlog_recover_check_ail(mp, lip, gen); +#ifdef DEBUG + for (; lip; lip = xfs_trans_next_ail(mp, &cur)) + ASSERT(lip->li_type != XFS_LI_EFI); +#endif break; } @@ -3102,17 +3081,19 @@ xlog_recover_process_efis( */ efip = (xfs_efi_log_item_t *)lip; if (efip->efi_flags & XFS_EFI_RECOVERED) { - lip = xfs_trans_next_ail(mp, lip, &gen, NULL); + lip = xfs_trans_next_ail(mp, &cur); continue; } spin_unlock(&mp->m_ail_lock); error = xlog_recover_process_efi(mp, efip); - if (error) - return error; spin_lock(&mp->m_ail_lock); - lip = xfs_trans_next_ail(mp, lip, &gen, NULL); + if (error) + goto out; + lip = xfs_trans_next_ail(mp, &cur); } +out: + xfs_trans_ail_cursor_done(mp->m_ail, &cur); spin_unlock(&mp->m_ail_lock); return error; } diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c index db72b52cd428..7b8bfcf1d3da 100644 --- a/fs/xfs/xfs_trans_ail.c +++ b/fs/xfs/xfs_trans_ail.c @@ -98,6 +98,115 @@ xfs_trans_push_ail( } } +/* + * AIL traversal cursor initialisation. + * + * The cursor keeps track of where our current traversal is up + * to by tracking the next ƣtem in the list for us. However, for + * this to be safe, removing an object from the AIL needs to invalidate + * any cursor that points to it. hence the traversal cursor needs to + * be linked to the struct xfs_ail so that deletion can search all the + * active cursors for invalidation. + * + * We don't link the push cursor because it is embedded in the struct + * xfs_ail and hence easily findable. + */ +void +xfs_trans_ail_cursor_init( + struct xfs_ail *ailp, + struct xfs_ail_cursor *cur) +{ + cur->item = NULL; + if (cur == &ailp->xa_cursors) + return; + + cur->next = ailp->xa_cursors.next; + ailp->xa_cursors.next = cur; +} + +/* + * Set the cursor to the next item, because when we look + * up the cursor the current item may have been freed. + */ +STATIC void +xfs_trans_ail_cursor_set( + struct xfs_ail *ailp, + struct xfs_ail_cursor *cur, + struct xfs_log_item *lip) +{ + if (lip) + cur->item = xfs_ail_next(ailp, lip); +} + +/* + * Get the next item in the traversal and advance the cursor. + * If the cursor was invalidated (inidicated by a lip of 1), + * restart the traversal. + */ +STATIC struct xfs_log_item * +xfs_trans_ail_cursor_next( + struct xfs_ail *ailp, + struct xfs_ail_cursor *cur) +{ + struct xfs_log_item *lip = cur->item; + + if ((__psint_t)lip & 1) + lip = xfs_ail_min(ailp); + xfs_trans_ail_cursor_set(ailp, cur, lip); + return lip; +} + +/* + * Invalidate any cursor that is pointing to this item. This is + * called when an item is removed from the AIL. Any cursor pointing + * to this object is now invalid and the traversal needs to be + * terminated so it doesn't reference a freed object. We set the + * cursor item to a value of 1 so we can distinguish between an + * invalidation and the end of the list when getting the next item + * from the cursor. + */ +STATIC void +xfs_trans_ail_cursor_clear( + struct xfs_ail *ailp, + struct xfs_log_item *lip) +{ + struct xfs_ail_cursor *cur; + + /* need to search all cursors */ + for (cur = &ailp->xa_cursors; cur; cur = cur->next) { + if (cur->item == lip) + cur->item = (struct xfs_log_item *) + ((__psint_t)cur->item | 1); + } +} + +/* + * Now that the traversal is complete, we need to remove the cursor + * from the list of traversing cursors. Avoid removing the embedded + * push cursor, but use the fact it is alway present to make the + * list deletion simple. + */ +void +xfs_trans_ail_cursor_done( + struct xfs_ail *ailp, + struct xfs_ail_cursor *done) +{ + struct xfs_ail_cursor *prev = NULL; + struct xfs_ail_cursor *cur; + + done->item = NULL; + if (done == &ailp->xa_cursors) + return; + prev = &ailp->xa_cursors; + for (cur = prev->next; cur; prev = cur, cur = prev->next) { + if (cur == done) { + prev->next = cur->next; + break; + } + } + ASSERT(cur); +} + /* * Return the item in the AIL with the current lsn. * Return the current tree generation number for use @@ -105,20 +214,22 @@ xfs_trans_push_ail( */ STATIC xfs_log_item_t * xfs_trans_first_push_ail( - xfs_mount_t *mp, - int *gen, - xfs_lsn_t lsn) + struct xfs_ail *ailp, + struct xfs_ail_cursor *cur, + xfs_lsn_t lsn) { - xfs_log_item_t *lip; + xfs_log_item_t *lip; - lip = xfs_ail_min(mp->m_ail); - *gen = (int)mp->m_ail->xa_gen; + lip = xfs_ail_min(ailp); + xfs_trans_ail_cursor_set(ailp, cur, lip); if (lsn == 0) return lip; - list_for_each_entry(lip, &mp->m_ail->xa_ail, li_ail) { - if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0) + list_for_each_entry(lip, &ailp->xa_ail, li_ail) { + if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0) { + xfs_trans_ail_cursor_set(ailp, cur, lip); return lip; + } } return NULL; @@ -137,22 +248,21 @@ xfsaild_push( xfs_lsn_t target = ailp->xa_target; xfs_lsn_t lsn; xfs_log_item_t *lip; - int gen; - int restarts; int flush_log, count, stuck; xfs_mount_t *mp = ailp->xa_mount; - -#define XFS_TRANS_PUSH_AIL_RESTARTS 10 + struct xfs_ail_cursor *cur = &ailp->xa_cursors; spin_lock(&mp->m_ail_lock); - lip = xfs_trans_first_push_ail(mp, &gen, *last_lsn); + xfs_trans_ail_cursor_init(ailp, cur); + lip = xfs_trans_first_push_ail(ailp, cur, *last_lsn); if (!lip || XFS_FORCED_SHUTDOWN(mp)) { /* * AIL is empty or our push has reached the end. */ + xfs_trans_ail_cursor_done(ailp, cur); spin_unlock(&mp->m_ail_lock); last_pushed_lsn = 0; - goto out; + return tout; } XFS_STATS_INC(xs_push_ail); @@ -170,7 +280,7 @@ xfsaild_push( */ tout = 10; lsn = lip->li_lsn; - flush_log = stuck = count = restarts = 0; + flush_log = stuck = count = 0; while ((XFS_LSN_CMP(lip->li_lsn, target) < 0)) { int lock_result; /* @@ -245,13 +355,12 @@ xfsaild_push( if (stuck > 100) break; - lip = xfs_trans_next_ail(mp, lip, &gen, &restarts); + lip = xfs_trans_ail_cursor_next(ailp, cur); if (lip == NULL) break; - if (restarts > XFS_TRANS_PUSH_AIL_RESTARTS) - break; lsn = lip->li_lsn; } + xfs_trans_ail_cursor_done(ailp, cur); spin_unlock(&mp->m_ail_lock); if (flush_log) { @@ -275,8 +384,7 @@ xfsaild_push( */ tout += 20; last_pushed_lsn = 0; - } else if ((restarts > XFS_TRANS_PUSH_AIL_RESTARTS) || - ((stuck * 100) / count > 90)) { + } else if ((stuck * 100) / count > 90) { /* * Either there is a lot of contention on the AIL or we * are stuck due to operations in progress. "Stuck" in this @@ -288,7 +396,6 @@ xfsaild_push( */ tout += 10; } -out: *last_lsn = last_pushed_lsn; return tout; } /* xfsaild_push */ @@ -348,9 +455,6 @@ xfs_trans_unlocked_item( * we move in the AIL is the minimum one, update the tail lsn in the * log manager. * - * Increment the AIL's generation count to indicate that the tree - * has changed. - * * This function must be called with the AIL lock held. The lock * is dropped before returning. */ @@ -368,14 +472,13 @@ xfs_trans_update_ail( if (lip->li_flags & XFS_LI_IN_AIL) { dlip = xfs_ail_delete(mp->m_ail, lip); ASSERT(dlip == lip); + xfs_trans_ail_cursor_clear(mp->m_ail, dlip); } else { lip->li_flags |= XFS_LI_IN_AIL; } lip->li_lsn = lsn; - xfs_ail_insert(mp->m_ail, lip); - mp->m_ail->xa_gen++; if (mlip == dlip) { mlip = xfs_ail_min(mp->m_ail); @@ -415,11 +518,11 @@ xfs_trans_delete_ail( mlip = xfs_ail_min(mp->m_ail); dlip = xfs_ail_delete(mp->m_ail, lip); ASSERT(dlip == lip); + xfs_trans_ail_cursor_clear(mp->m_ail, dlip); lip->li_flags &= ~XFS_LI_IN_AIL; lip->li_lsn = 0; - mp->m_ail->xa_gen++; if (mlip == dlip) { mlip = xfs_ail_min(mp->m_ail); @@ -455,46 +558,29 @@ xfs_trans_delete_ail( */ xfs_log_item_t * xfs_trans_first_ail( - xfs_mount_t *mp, - int *gen) + struct xfs_mount *mp, + struct xfs_ail_cursor *cur) { - xfs_log_item_t *lip; + xfs_log_item_t *lip; + struct xfs_ail *ailp = mp->m_ail; - lip = xfs_ail_min(mp->m_ail); - *gen = (int)mp->m_ail->xa_gen; + lip = xfs_ail_min(ailp); + xfs_trans_ail_cursor_set(ailp, cur, lip); return lip; } /* - * If the generation count of the tree has not changed since the - * caller last took something from the AIL, then return the elmt - * in the tree which follows the one given. If the count has changed, - * then return the minimum elmt of the AIL and bump the restarts counter - * if one is given. + * Grab the next item in the AIL from the cursor passed in. */ xfs_log_item_t * xfs_trans_next_ail( - xfs_mount_t *mp, - xfs_log_item_t *lip, - int *gen, - int *restarts) + struct xfs_mount *mp, + struct xfs_ail_cursor *cur) { - xfs_log_item_t *nlip; + struct xfs_ail *ailp = mp->m_ail; - ASSERT(mp && lip && gen); - if (mp->m_ail->xa_gen == *gen) { - nlip = xfs_ail_next(mp->m_ail, lip); - } else { - nlip = xfs_ail_min(mp->m_ail); - *gen = (int)mp->m_ail->xa_gen; - if (restarts != NULL) { - XFS_STATS_INC(xs_push_ail_restarts); - (*restarts)++; - } - } - - return (nlip); + return xfs_trans_ail_cursor_next(ailp, cur); } @@ -517,6 +603,7 @@ xfs_trans_ail_init( xfs_mount_t *mp) { struct xfs_ail *ailp; + int error; ailp = kmem_zalloc(sizeof(struct xfs_ail), KM_MAYFAIL); if (!ailp) @@ -524,7 +611,15 @@ xfs_trans_ail_init( ailp->xa_mount = mp; INIT_LIST_HEAD(&ailp->xa_ail); - return xfsaild_start(ailp); + error = xfsaild_start(ailp); + if (error) + goto out_free_ailp; + mp->m_ail = ailp; + return 0; + +out_free_ailp: + kmem_free(ailp); + return error; } void diff --git a/fs/xfs/xfs_trans_priv.h b/fs/xfs/xfs_trans_priv.h index 98317fdc33b5..f114d388570a 100644 --- a/fs/xfs/xfs_trans_priv.h +++ b/fs/xfs/xfs_trans_priv.h @@ -43,6 +43,44 @@ xfs_log_busy_slot_t *xfs_trans_add_busy(xfs_trans_t *tp, xfs_agnumber_t ag, xfs_extlen_t idx); +/* + * AIL traversal cursor. + * + * Rather than using a generation number for detecting changes in the ail, use + * a cursor that is protected by the ail lock. The aild cursor exists in the + * struct xfs_ail, but other traversals can declare it on the stack and link it + * to the ail list. + * + * When an object is deleted from or moved int the AIL, the cursor list is + * searched to see if the object is a designated cursor item. If it is, it is + * deleted from the cursor so that the next time the cursor is used traversal + * will return to the start. + * + * This means a traversal colliding with a removal will cause a restart of the + * list scan, rather than any insertion or deletion anywhere in the list. The + * low bit of the item pointer is set if the cursor has been invalidated so + * that we can tell the difference between invalidation and reaching the end + * of the list to trigger traversal restarts. + */ +struct xfs_ail_cursor { + struct xfs_ail_cursor *next; + struct xfs_log_item *item; +}; + +/* + * Private AIL structures. + * + * Eventually we need to drive the locking in here as well. + */ +struct xfs_ail { + struct xfs_mount *xa_mount; + struct list_head xa_ail; + uint xa_gen; + struct task_struct *xa_task; + xfs_lsn_t xa_target; + struct xfs_ail_cursor xa_cursors; +}; + /* * From xfs_trans_ail.c */ @@ -52,20 +90,15 @@ void xfs_trans_update_ail(struct xfs_mount *mp, void xfs_trans_delete_ail(struct xfs_mount *mp, struct xfs_log_item *lip) __releases(mp->m_ail_lock); -struct xfs_log_item *xfs_trans_first_ail(struct xfs_mount *, int *); -struct xfs_log_item *xfs_trans_next_ail(struct xfs_mount *, - struct xfs_log_item *, int *, int *); +struct xfs_log_item *xfs_trans_first_ail(struct xfs_mount *mp, + struct xfs_ail_cursor *cur); +struct xfs_log_item *xfs_trans_next_ail(struct xfs_mount *mp, + struct xfs_ail_cursor *cur); -/* - * AIL push thread support - */ -struct xfs_ail { - struct xfs_mount *xa_mount; - struct list_head xa_ail; - uint xa_gen; - struct task_struct *xa_task; - xfs_lsn_t xa_target; -}; +void xfs_trans_ail_cursor_init(struct xfs_ail *ailp, + struct xfs_ail_cursor *cur); +void xfs_trans_ail_cursor_done(struct xfs_ail *ailp, + struct xfs_ail_cursor *cur); long xfsaild_push(struct xfs_ail *, xfs_lsn_t *); void xfsaild_wakeup(struct xfs_ail *, xfs_lsn_t);