diff options
| -rw-r--r-- | fs/xfs/xfs_trans_ail.c | 67 |
1 files changed, 29 insertions, 38 deletions
diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c index 43233e9..c15aa29 100644 --- a/fs/xfs/xfs_trans_ail.c +++ b/fs/xfs/xfs_trans_ail.c @@ -299,7 +299,7 @@ xfs_trans_ail_cursor_last( * Splice the log item list into the AIL at the given LSN. We splice to the * tail of the given LSN to maintain insert order for push traversals. The * cursor is optional, allowing repeated updates to the same LSN to avoid - * repeated traversals. + * repeated traversals. This should not be called with an empty list. */ static void xfs_ail_splice( @@ -308,50 +308,39 @@ xfs_ail_splice( struct list_head *list, xfs_lsn_t lsn) { - struct xfs_log_item *lip = cur ? cur->item : NULL; - struct xfs_log_item *next_lip; + struct xfs_log_item *lip; + + ASSERT(!list_empty(list)); /* - * Get a new cursor if we don't have a placeholder or the existing one - * has been invalidated. + * Use the cursor to determine the insertion point if one is + * provided. If not, or if the one we got is not valid, + * find the place in the AIL where the items belong. */ - if (!lip || (__psint_t)lip & 1) { + lip = cur ? cur->item : NULL; + if (!lip || (__psint_t) lip & 1) lip = __xfs_trans_ail_cursor_last(ailp, lsn); - if (!lip) { - /* The list is empty, so just splice and return. */ - if (cur) - cur->item = NULL; - list_splice(list, &ailp->xa_ail); - return; - } - } + /* + * If a cursor is provided, we know we're processing the AIL + * in lsn order, and future items to be spliced in will + * follow the last one being inserted now. Update the + * cursor to point to that last item, now while we have a + * reliable pointer to it. + */ + if (cur) + cur->item = list_entry(list->prev, struct xfs_log_item, li_ail); /* - * Our cursor points to the item we want to insert _after_, so we have - * to update the cursor to point to the end of the list we are splicing - * in so that it points to the correct location for the next splice. - * i.e. before the splice - * - * lsn -> lsn -> lsn + x -> lsn + x ... - * ^ - * | cursor points here - * - * After the splice we have: - * - * lsn -> lsn -> lsn -> lsn -> .... -> lsn -> lsn + x -> lsn + x ... - * ^ ^ - * | cursor points here | needs to move here - * - * So we set the cursor to the last item in the list to be spliced - * before we execute the splice, resulting in the cursor pointing to - * the correct item after the splice occurs. + * Finally perform the splice. Unless the AIL was empty, + * lip points to the item in the AIL _after_ which the new + * items should go. If lip is null the AIL was empty, so + * the new items go at the head of the AIL. */ - if (cur) { - next_lip = list_entry(list->prev, struct xfs_log_item, li_ail); - cur->item = next_lip; - } - list_splice(list, &lip->li_ail); + if (lip) + list_splice(list, &lip->li_ail); + else + list_splice(list, &ailp->xa_ail); } /* @@ -682,6 +671,7 @@ xfs_trans_ail_update_bulk( int i; LIST_HEAD(tmp); + ASSERT(nr_items > 0); /* Not required, but true. */ mlip = xfs_ail_min(ailp); for (i = 0; i < nr_items; i++) { @@ -701,7 +691,8 @@ xfs_trans_ail_update_bulk( list_add(&lip->li_ail, &tmp); } - xfs_ail_splice(ailp, cur, &tmp, lsn); + if (!list_empty(&tmp)) + xfs_ail_splice(ailp, cur, &tmp, lsn); if (!mlip_changed) { spin_unlock(&ailp->xa_lock); |
