diff options
Diffstat (limited to 'fs/xfs/xfs_trans_ail.c')
-rw-r--r-- | fs/xfs/xfs_trans_ail.c | 239 |
1 files changed, 103 insertions, 136 deletions
diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c index a4c281b..ed9252b 100644 --- a/fs/xfs/xfs_trans_ail.c +++ b/fs/xfs/xfs_trans_ail.c @@ -26,6 +26,7 @@ #include "xfs_ag.h" #include "xfs_mount.h" #include "xfs_trans_priv.h" +#include "xfs_trace.h" #include "xfs_error.h" #ifdef DEBUG @@ -161,17 +162,11 @@ xfs_ail_max_lsn( } /* - * 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. + * The cursor keeps track of where our current traversal is up to by tracking + * the next item 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. */ STATIC void xfs_trans_ail_cursor_init( @@ -179,31 +174,12 @@ xfs_trans_ail_cursor_init( 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); + list_add_tail(&cur->list, &ailp->xa_cursors); } /* - * 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. + * Get the next item in the traversal and advance the cursor. If the cursor + * was invalidated (indicated by a lip of 1), restart the traversal. */ struct xfs_log_item * xfs_trans_ail_cursor_next( @@ -214,45 +190,31 @@ xfs_trans_ail_cursor_next( if ((__psint_t)lip & 1) lip = xfs_ail_min(ailp); - xfs_trans_ail_cursor_set(ailp, cur, lip); + if (lip) + cur->item = xfs_ail_next(ailp, lip); return lip; } /* - * 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 always present to make the - * list deletion simple. + * When the traversal is complete, we need to remove the cursor from the list + * of traversing cursors. */ void xfs_trans_ail_cursor_done( struct xfs_ail *ailp, - struct xfs_ail_cursor *done) + struct xfs_ail_cursor *cur) { - 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); + cur->item = NULL; + list_del_init(&cur->list); } /* - * 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. + * 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 low bit of the cursor item pointer 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( @@ -261,8 +223,7 @@ xfs_trans_ail_cursor_clear( { struct xfs_ail_cursor *cur; - /* need to search all cursors */ - for (cur = &ailp->xa_cursors; cur; cur = cur->next) { + list_for_each_entry(cur, &ailp->xa_cursors, list) { if (cur->item == lip) cur->item = (struct xfs_log_item *) ((__psint_t)cur->item | 1); @@ -270,9 +231,10 @@ xfs_trans_ail_cursor_clear( } /* - * Initialise the cursor to the first item in the AIL with the given @lsn. - * This searches the list from lowest LSN to highest. Pass a @lsn of zero - * to initialise the cursor to the first item in the AIL. + * Find the first item in the AIL with the given @lsn by searching in ascending + * LSN order and initialise the cursor to point to the next item for a + * ascending traversal. Pass a @lsn of zero to initialise the cursor to the + * first item in the AIL. Returns NULL if the list is empty. */ xfs_log_item_t * xfs_trans_ail_cursor_first( @@ -283,26 +245,24 @@ xfs_trans_ail_cursor_first( xfs_log_item_t *lip; xfs_trans_ail_cursor_init(ailp, cur); - lip = xfs_ail_min(ailp); - if (lsn == 0) + + if (lsn == 0) { + lip = xfs_ail_min(ailp); goto out; + } list_for_each_entry(lip, &ailp->xa_ail, li_ail) { if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0) goto out; } - lip = NULL; + return NULL; + out: - xfs_trans_ail_cursor_set(ailp, cur, lip); + if (lip) + cur->item = xfs_ail_next(ailp, lip); return lip; } -/* - * Initialise the cursor to the last item in the AIL with the given @lsn. - * This searches the list from highest LSN to lowest. If there is no item with - * the value of @lsn, then it sets the cursor to the last item with an LSN lower - * than @lsn. - */ static struct xfs_log_item * __xfs_trans_ail_cursor_last( struct xfs_ail *ailp, @@ -318,8 +278,10 @@ __xfs_trans_ail_cursor_last( } /* - * Initialise the cursor to the last item in the AIL with the given @lsn. - * This searches the list from highest LSN to lowest. + * Find the last item in the AIL with the given @lsn by searching in descending + * LSN order and initialise the cursor to point to that item. If there is no + * item with the value of @lsn, then it sets the cursor to the last item with an + * LSN lower than @lsn. Returns NULL if the list is empty. */ struct xfs_log_item * xfs_trans_ail_cursor_last( @@ -333,10 +295,10 @@ xfs_trans_ail_cursor_last( } /* - * splice the log item list into the AIL at the given LSN. We splice to the + * 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( @@ -345,50 +307,39 @@ 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); } /* @@ -409,25 +360,36 @@ xfsaild_push( struct xfs_ail *ailp) { xfs_mount_t *mp = ailp->xa_mount; - struct xfs_ail_cursor *cur = &ailp->xa_cursors; + struct xfs_ail_cursor cur; xfs_log_item_t *lip; xfs_lsn_t lsn; xfs_lsn_t target; long tout = 10; - int flush_log = 0; int stuck = 0; int count = 0; int push_xfsbufd = 0; + /* + * If last time we ran we encountered pinned items, force the log first + * and wait for it before pushing again. + */ spin_lock(&ailp->xa_lock); + if (ailp->xa_last_pushed_lsn == 0 && ailp->xa_log_flush && + !list_empty(&ailp->xa_ail)) { + ailp->xa_log_flush = 0; + spin_unlock(&ailp->xa_lock); + XFS_STATS_INC(xs_push_ail_flush); + xfs_log_force(mp, XFS_LOG_SYNC); + spin_lock(&ailp->xa_lock); + } + target = ailp->xa_target; - xfs_trans_ail_cursor_init(ailp, cur); - lip = xfs_trans_ail_cursor_first(ailp, cur, ailp->xa_last_pushed_lsn); + lip = xfs_trans_ail_cursor_first(ailp, &cur, ailp->xa_last_pushed_lsn); if (!lip || XFS_FORCED_SHUTDOWN(mp)) { /* * AIL is empty or our push has reached the end. */ - xfs_trans_ail_cursor_done(ailp, cur); + xfs_trans_ail_cursor_done(ailp, &cur); spin_unlock(&ailp->xa_lock); goto out_done; } @@ -464,16 +426,20 @@ xfsaild_push( switch (lock_result) { case XFS_ITEM_SUCCESS: XFS_STATS_INC(xs_push_ail_success); + trace_xfs_ail_push(lip); + IOP_PUSH(lip); ailp->xa_last_pushed_lsn = lsn; break; case XFS_ITEM_PUSHBUF: XFS_STATS_INC(xs_push_ail_pushbuf); + trace_xfs_ail_pushbuf(lip); if (!IOP_PUSHBUF(lip)) { + trace_xfs_ail_pushbuf_pinned(lip); stuck++; - flush_log = 1; + ailp->xa_log_flush++; } else { ailp->xa_last_pushed_lsn = lsn; } @@ -482,12 +448,15 @@ xfsaild_push( case XFS_ITEM_PINNED: XFS_STATS_INC(xs_push_ail_pinned); + trace_xfs_ail_pinned(lip); + stuck++; - flush_log = 1; + ailp->xa_log_flush++; break; case XFS_ITEM_LOCKED: XFS_STATS_INC(xs_push_ail_locked); + trace_xfs_ail_locked(lip); stuck++; break; @@ -519,24 +488,14 @@ xfsaild_push( if (stuck > 100) break; - lip = xfs_trans_ail_cursor_next(ailp, cur); + lip = xfs_trans_ail_cursor_next(ailp, &cur); if (lip == NULL) break; lsn = lip->li_lsn; } - xfs_trans_ail_cursor_done(ailp, cur); + xfs_trans_ail_cursor_done(ailp, &cur); spin_unlock(&ailp->xa_lock); - if (flush_log) { - /* - * If something we need to push out was pinned, then - * push out the log so it will become unpinned and - * move forward in the AIL. - */ - XFS_STATS_INC(xs_push_ail_flush); - xfs_log_force(mp, 0); - } - if (push_xfsbufd) { /* we've got delayed write buffers to flush */ wake_up_process(mp->m_ddev_targp->bt_task); @@ -547,6 +506,7 @@ out_done: if (!count) { /* We're past our target or empty, so idle */ ailp->xa_last_pushed_lsn = 0; + ailp->xa_log_flush = 0; tout = 50; } else if (XFS_LSN_CMP(lsn, target) >= 0) { @@ -565,9 +525,13 @@ out_done: * were stuck. * * Backoff a bit more to allow some I/O to complete before - * continuing from where we were. + * restarting from the start of the AIL. This prevents us + * from spinning on the same items, and if they are pinned will + * all the restart to issue a log force to unpin the stuck + * items. */ tout = 20; + ailp->xa_last_pushed_lsn = 0; } return tout; @@ -726,6 +690,7 @@ 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++) { @@ -745,7 +710,8 @@ 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); @@ -864,6 +830,7 @@ xfs_trans_ail_init( ailp->xa_mount = mp; INIT_LIST_HEAD(&ailp->xa_ail); + INIT_LIST_HEAD(&ailp->xa_cursors); spin_lock_init(&ailp->xa_lock); ailp->xa_task = kthread_run(xfsaild, ailp, "xfsaild/%s", |