| /* |
| * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc. |
| * Copyright (c) 2008 Dave Chinner |
| * All Rights Reserved. |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License as |
| * published by the Free Software Foundation. |
| * |
| * This program is distributed in the hope that it would be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| #include "xfs.h" |
| #include "xfs_fs.h" |
| #include "xfs_types.h" |
| #include "xfs_log.h" |
| #include "xfs_inum.h" |
| #include "xfs_trans.h" |
| #include "xfs_sb.h" |
| #include "xfs_ag.h" |
| #include "xfs_mount.h" |
| #include "xfs_trans_priv.h" |
| #include "xfs_error.h" |
| |
| struct workqueue_struct *xfs_ail_wq; /* AIL workqueue */ |
| |
| #ifdef DEBUG |
| /* |
| * Check that the list is sorted as it should be. |
| */ |
| STATIC void |
| xfs_ail_check( |
| struct xfs_ail *ailp, |
| xfs_log_item_t *lip) |
| { |
| xfs_log_item_t *prev_lip; |
| |
| if (list_empty(&ailp->xa_ail)) |
| return; |
| |
| /* |
| * Check the next and previous entries are valid. |
| */ |
| ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0); |
| prev_lip = list_entry(lip->li_ail.prev, xfs_log_item_t, li_ail); |
| if (&prev_lip->li_ail != &ailp->xa_ail) |
| ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0); |
| |
| prev_lip = list_entry(lip->li_ail.next, xfs_log_item_t, li_ail); |
| if (&prev_lip->li_ail != &ailp->xa_ail) |
| ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) >= 0); |
| |
| |
| #ifdef XFS_TRANS_DEBUG |
| /* |
| * Walk the list checking lsn ordering, and that every entry has the |
| * XFS_LI_IN_AIL flag set. This is really expensive, so only do it |
| * when specifically debugging the transaction subsystem. |
| */ |
| prev_lip = list_entry(&ailp->xa_ail, xfs_log_item_t, li_ail); |
| list_for_each_entry(lip, &ailp->xa_ail, li_ail) { |
| if (&prev_lip->li_ail != &ailp->xa_ail) |
| ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0); |
| ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0); |
| prev_lip = lip; |
| } |
| #endif /* XFS_TRANS_DEBUG */ |
| } |
| #else /* !DEBUG */ |
| #define xfs_ail_check(a,l) |
| #endif /* DEBUG */ |
| |
| /* |
| * Return a pointer to the first item in the AIL. If the AIL is empty, then |
| * return NULL. |
| */ |
| static xfs_log_item_t * |
| xfs_ail_min( |
| struct xfs_ail *ailp) |
| { |
| if (list_empty(&ailp->xa_ail)) |
| return NULL; |
| |
| return list_first_entry(&ailp->xa_ail, xfs_log_item_t, li_ail); |
| } |
| |
| /* |
| * Return a pointer to the last item in the AIL. If the AIL is empty, then |
| * return NULL. |
| */ |
| static xfs_log_item_t * |
| xfs_ail_max( |
| struct xfs_ail *ailp) |
| { |
| if (list_empty(&ailp->xa_ail)) |
| return NULL; |
| |
| return list_entry(ailp->xa_ail.prev, xfs_log_item_t, li_ail); |
| } |
| |
| /* |
| * Return a pointer to the item which follows the given item in the AIL. If |
| * the given item is the last item in the list, then return NULL. |
| */ |
| static xfs_log_item_t * |
| xfs_ail_next( |
| struct xfs_ail *ailp, |
| xfs_log_item_t *lip) |
| { |
| if (lip->li_ail.next == &ailp->xa_ail) |
| return NULL; |
| |
| return list_first_entry(&lip->li_ail, xfs_log_item_t, li_ail); |
| } |
| |
| /* |
| * This is called by the log manager code to determine the LSN of the tail of |
| * the log. This is exactly the LSN of the first item in the AIL. If the AIL |
| * is empty, then this function returns 0. |
| * |
| * We need the AIL lock in order to get a coherent read of the lsn of the last |
| * item in the AIL. |
| */ |
| xfs_lsn_t |
| xfs_ail_min_lsn( |
| struct xfs_ail *ailp) |
| { |
| xfs_lsn_t lsn = 0; |
| xfs_log_item_t *lip; |
| |
| spin_lock(&ailp->xa_lock); |
| lip = xfs_ail_min(ailp); |
| if (lip) |
| lsn = lip->li_lsn; |
| spin_unlock(&ailp->xa_lock); |
| |
| return lsn; |
| } |
| |
| /* |
| * Return the maximum lsn held in the AIL, or zero if the AIL is empty. |
| */ |
| static xfs_lsn_t |
| xfs_ail_max_lsn( |
| struct xfs_ail *ailp) |
| { |
| xfs_lsn_t lsn = 0; |
| xfs_log_item_t *lip; |
| |
| spin_lock(&ailp->xa_lock); |
| lip = xfs_ail_max(ailp); |
| if (lip) |
| lsn = lip->li_lsn; |
| spin_unlock(&ailp->xa_lock); |
| |
| return 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. |
| */ |
| STATIC 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. |
| */ |
| 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; |
| } |
| |
| /* |
| * 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. |
| */ |
| 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); |
| } |
| |
| /* |
| * 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); |
| } |
| } |
| |
| /* |
| * 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. |
| */ |
| xfs_log_item_t * |
| xfs_trans_ail_cursor_first( |
| struct xfs_ail *ailp, |
| struct xfs_ail_cursor *cur, |
| xfs_lsn_t lsn) |
| { |
| xfs_log_item_t *lip; |
| |
| xfs_trans_ail_cursor_init(ailp, cur); |
| lip = xfs_ail_min(ailp); |
| if (lsn == 0) |
| 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; |
| out: |
| xfs_trans_ail_cursor_set(ailp, cur, 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, |
| xfs_lsn_t lsn) |
| { |
| xfs_log_item_t *lip; |
| |
| list_for_each_entry_reverse(lip, &ailp->xa_ail, li_ail) { |
| if (XFS_LSN_CMP(lip->li_lsn, lsn) <= 0) |
| return lip; |
| } |
| return NULL; |
| } |
| |
| /* |
| * Initialise the cursor to the last item in the AIL with the given @lsn. |
| * This searches the list from highest LSN to lowest. |
| */ |
| struct xfs_log_item * |
| xfs_trans_ail_cursor_last( |
| struct xfs_ail *ailp, |
| struct xfs_ail_cursor *cur, |
| xfs_lsn_t lsn) |
| { |
| xfs_trans_ail_cursor_init(ailp, cur); |
| cur->item = __xfs_trans_ail_cursor_last(ailp, lsn); |
| return cur->item; |
| } |
| |
| /* |
| * 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. |
| */ |
| static void |
| xfs_ail_splice( |
| struct xfs_ail *ailp, |
| struct xfs_ail_cursor *cur, |
| struct list_head *list, |
| xfs_lsn_t lsn) |
| { |
| struct xfs_log_item *lip = cur ? cur->item : NULL; |
| struct xfs_log_item *next_lip; |
| |
| /* |
| * Get a new cursor if we don't have a placeholder or the existing one |
| * has been invalidated. |
| */ |
| 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; |
| } |
| } |
| |
| /* |
| * 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. |
| */ |
| if (cur) { |
| next_lip = list_entry(list->prev, struct xfs_log_item, li_ail); |
| cur->item = next_lip; |
| } |
| list_splice(list, &lip->li_ail); |
| } |
| |
| /* |
| * Delete the given item from the AIL. Return a pointer to the item. |
| */ |
| static void |
| xfs_ail_delete( |
| struct xfs_ail *ailp, |
| xfs_log_item_t *lip) |
| { |
| xfs_ail_check(ailp, lip); |
| list_del(&lip->li_ail); |
| xfs_trans_ail_cursor_clear(ailp, lip); |
| } |
| |
| /* |
| * xfs_ail_worker does the work of pushing on the AIL. It will requeue itself |
| * to run at a later time if there is more work to do to complete the push. |
| */ |
| STATIC void |
| xfs_ail_worker( |
| struct work_struct *work) |
| { |
| struct xfs_ail *ailp = container_of(to_delayed_work(work), |
| struct xfs_ail, xa_work); |
| xfs_mount_t *mp = ailp->xa_mount; |
| struct xfs_ail_cursor *cur = &ailp->xa_cursors; |
| 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; |
| |
| 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); |
| 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(&ailp->xa_lock); |
| goto out_done; |
| } |
| |
| XFS_STATS_INC(xs_push_ail); |
| |
| /* |
| * While the item we are looking at is below the given threshold |
| * try to flush it out. We'd like not to stop until we've at least |
| * tried to push on everything in the AIL with an LSN less than |
| * the given threshold. |
| * |
| * However, we will stop after a certain number of pushes and wait |
| * for a reduced timeout to fire before pushing further. This |
| * prevents use from spinning when we can't do anything or there is |
| * lots of contention on the AIL lists. |
| */ |
| lsn = lip->li_lsn; |
| while ((XFS_LSN_CMP(lip->li_lsn, target) <= 0)) { |
| int lock_result; |
| /* |
| * If we can lock the item without sleeping, unlock the AIL |
| * lock and flush the item. Then re-grab the AIL lock so we |
| * can look for the next item on the AIL. List changes are |
| * handled by the AIL lookup functions internally |
| * |
| * If we can't lock the item, either its holder will flush it |
| * or it is already being flushed or it is being relogged. In |
| * any of these case it is being taken care of and we can just |
| * skip to the next item in the list. |
| */ |
| lock_result = IOP_TRYLOCK(lip); |
| spin_unlock(&ailp->xa_lock); |
| switch (lock_result) { |
| case XFS_ITEM_SUCCESS: |
| XFS_STATS_INC(xs_push_ail_success); |
| IOP_PUSH(lip); |
| ailp->xa_last_pushed_lsn = lsn; |
| break; |
| |
| case XFS_ITEM_PUSHBUF: |
| XFS_STATS_INC(xs_push_ail_pushbuf); |
| IOP_PUSHBUF(lip); |
| ailp->xa_last_pushed_lsn = lsn; |
| push_xfsbufd = 1; |
| break; |
| |
| case XFS_ITEM_PINNED: |
| XFS_STATS_INC(xs_push_ail_pinned); |
| stuck++; |
| flush_log = 1; |
| break; |
| |
| case XFS_ITEM_LOCKED: |
| XFS_STATS_INC(xs_push_ail_locked); |
| stuck++; |
| break; |
| |
| default: |
| ASSERT(0); |
| break; |
| } |
| |
| spin_lock(&ailp->xa_lock); |
| /* should we bother continuing? */ |
| if (XFS_FORCED_SHUTDOWN(mp)) |
| break; |
| ASSERT(mp->m_log); |
| |
| count++; |
| |
| /* |
| * Are there too many items we can't do anything with? |
| * If we we are skipping too many items because we can't flush |
| * them or they are already being flushed, we back off and |
| * given them time to complete whatever operation is being |
| * done. i.e. remove pressure from the AIL while we can't make |
| * progress so traversals don't slow down further inserts and |
| * removals to/from the AIL. |
| * |
| * The value of 100 is an arbitrary magic number based on |
| * observation. |
| */ |
| if (stuck > 100) |
| break; |
| |
| lip = xfs_trans_ail_cursor_next(ailp, cur); |
| if (lip == NULL) |
| break; |
| lsn = lip->li_lsn; |
| } |
| 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); |
| } |
| |
| /* assume we have more work to do in a short while */ |
| out_done: |
| if (!count) { |
| /* We're past our target or empty, so idle */ |
| ailp->xa_last_pushed_lsn = 0; |
| |
| /* |
| * We clear the XFS_AIL_PUSHING_BIT first before checking |
| * whether the target has changed. If the target has changed, |
| * this pushes the requeue race directly onto the result of the |
| * atomic test/set bit, so we are guaranteed that either the |
| * the pusher that changed the target or ourselves will requeue |
| * the work (but not both). |
| */ |
| clear_bit(XFS_AIL_PUSHING_BIT, &ailp->xa_flags); |
| smp_rmb(); |
| if (XFS_LSN_CMP(ailp->xa_target, target) == 0 || |
| test_and_set_bit(XFS_AIL_PUSHING_BIT, &ailp->xa_flags)) |
| return; |
| |
| tout = 50; |
| } else if (XFS_LSN_CMP(lsn, target) >= 0) { |
| /* |
| * We reached the target so wait a bit longer for I/O to |
| * complete and remove pushed items from the AIL before we |
| * start the next scan from the start of the AIL. |
| */ |
| tout = 50; |
| ailp->xa_last_pushed_lsn = 0; |
| } 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 |
| * case is defined as >90% of the items we tried to push |
| * were stuck. |
| * |
| * Backoff a bit more to allow some I/O to complete before |
| * continuing from where we were. |
| */ |
| tout = 20; |
| } |
| |
| /* There is more to do, requeue us. */ |
| queue_delayed_work(xfs_syncd_wq, &ailp->xa_work, |
| msecs_to_jiffies(tout)); |
| } |
| |
| /* |
| * This routine is called to move the tail of the AIL forward. It does this by |
| * trying to flush items in the AIL whose lsns are below the given |
| * threshold_lsn. |
| * |
| * The push is run asynchronously in a workqueue, which means the caller needs |
| * to handle waiting on the async flush for space to become available. |
| * We don't want to interrupt any push that is in progress, hence we only queue |
| * work if we set the pushing bit approriately. |
| * |
| * We do this unlocked - we only need to know whether there is anything in the |
| * AIL at the time we are called. We don't need to access the contents of |
| * any of the objects, so the lock is not needed. |
| */ |
| void |
| xfs_ail_push( |
| struct xfs_ail *ailp, |
| xfs_lsn_t threshold_lsn) |
| { |
| xfs_log_item_t *lip; |
| |
| lip = xfs_ail_min(ailp); |
| if (!lip || XFS_FORCED_SHUTDOWN(ailp->xa_mount) || |
| XFS_LSN_CMP(threshold_lsn, ailp->xa_target) <= 0) |
| return; |
| |
| /* |
| * Ensure that the new target is noticed in push code before it clears |
| * the XFS_AIL_PUSHING_BIT. |
| */ |
| smp_wmb(); |
| xfs_trans_ail_copy_lsn(ailp, &ailp->xa_target, &threshold_lsn); |
| if (!test_and_set_bit(XFS_AIL_PUSHING_BIT, &ailp->xa_flags)) |
| queue_delayed_work(xfs_syncd_wq, &ailp->xa_work, 0); |
| } |
| |
| /* |
| * Push out all items in the AIL immediately |
| */ |
| void |
| xfs_ail_push_all( |
| struct xfs_ail *ailp) |
| { |
| xfs_lsn_t threshold_lsn = xfs_ail_max_lsn(ailp); |
| |
| if (threshold_lsn) |
| xfs_ail_push(ailp, threshold_lsn); |
| } |
| |
| /* |
| * This is to be called when an item is unlocked that may have |
| * been in the AIL. It will wake up the first member of the AIL |
| * wait list if this item's unlocking might allow it to progress. |
| * If the item is in the AIL, then we need to get the AIL lock |
| * while doing our checking so we don't race with someone going |
| * to sleep waiting for this event in xfs_trans_push_ail(). |
| */ |
| void |
| xfs_trans_unlocked_item( |
| struct xfs_ail *ailp, |
| xfs_log_item_t *lip) |
| { |
| xfs_log_item_t *min_lip; |
| |
| /* |
| * If we're forcibly shutting down, we may have |
| * unlocked log items arbitrarily. The last thing |
| * we want to do is to move the tail of the log |
| * over some potentially valid data. |
| */ |
| if (!(lip->li_flags & XFS_LI_IN_AIL) || |
| XFS_FORCED_SHUTDOWN(ailp->xa_mount)) { |
| return; |
| } |
| |
| /* |
| * This is the one case where we can call into xfs_ail_min() |
| * without holding the AIL lock because we only care about the |
| * case where we are at the tail of the AIL. If the object isn't |
| * at the tail, it doesn't matter what result we get back. This |
| * is slightly racy because since we were just unlocked, we could |
| * go to sleep between the call to xfs_ail_min and the call to |
| * xfs_log_move_tail, have someone else lock us, commit to us disk, |
| * move us out of the tail of the AIL, and then we wake up. However, |
| * the call to xfs_log_move_tail() doesn't do anything if there's |
| * not enough free space to wake people up so we're safe calling it. |
| */ |
| min_lip = xfs_ail_min(ailp); |
| |
| if (min_lip == lip) |
| xfs_log_move_tail(ailp->xa_mount, 1); |
| } /* xfs_trans_unlocked_item */ |
| |
| /* |
| * xfs_trans_ail_update - bulk AIL insertion operation. |
| * |
| * @xfs_trans_ail_update takes an array of log items that all need to be |
| * positioned at the same LSN in the AIL. If an item is not in the AIL, it will |
| * be added. Otherwise, it will be repositioned by removing it and re-adding |
| * it to the AIL. If we move the first item in the AIL, update the log tail to |
| * match the new minimum LSN in the AIL. |
| * |
| * This function takes the AIL lock once to execute the update operations on |
| * all the items in the array, and as such should not be called with the AIL |
| * lock held. As a result, once we have the AIL lock, we need to check each log |
| * item LSN to confirm it needs to be moved forward in the AIL. |
| * |
| * To optimise the insert operation, we delete all the items from the AIL in |
| * the first pass, moving them into a temporary list, then splice the temporary |
| * list into the correct position in the AIL. This avoids needing to do an |
| * insert operation on every item. |
| * |
| * This function must be called with the AIL lock held. The lock is dropped |
| * before returning. |
| */ |
| void |
| xfs_trans_ail_update_bulk( |
| struct xfs_ail *ailp, |
| struct xfs_ail_cursor *cur, |
| struct xfs_log_item **log_items, |
| int nr_items, |
| xfs_lsn_t lsn) __releases(ailp->xa_lock) |
| { |
| xfs_log_item_t *mlip; |
| xfs_lsn_t tail_lsn; |
| int mlip_changed = 0; |
| int i; |
| LIST_HEAD(tmp); |
| |
| mlip = xfs_ail_min(ailp); |
| |
| for (i = 0; i < nr_items; i++) { |
| struct xfs_log_item *lip = log_items[i]; |
| if (lip->li_flags & XFS_LI_IN_AIL) { |
| /* check if we really need to move the item */ |
| if (XFS_LSN_CMP(lsn, lip->li_lsn) <= 0) |
| continue; |
| |
| xfs_ail_delete(ailp, lip); |
| if (mlip == lip) |
| mlip_changed = 1; |
| } else { |
| lip->li_flags |= XFS_LI_IN_AIL; |
| } |
| lip->li_lsn = lsn; |
| list_add(&lip->li_ail, &tmp); |
| } |
| |
| xfs_ail_splice(ailp, cur, &tmp, lsn); |
| |
| if (!mlip_changed) { |
| spin_unlock(&ailp->xa_lock); |
| return; |
| } |
| |
| /* |
| * It is not safe to access mlip after the AIL lock is dropped, so we |
| * must get a copy of li_lsn before we do so. This is especially |
| * important on 32-bit platforms where accessing and updating 64-bit |
| * values like li_lsn is not atomic. |
| */ |
| mlip = xfs_ail_min(ailp); |
| tail_lsn = mlip->li_lsn; |
| spin_unlock(&ailp->xa_lock); |
| xfs_log_move_tail(ailp->xa_mount, tail_lsn); |
| } |
| |
| /* |
| * xfs_trans_ail_delete_bulk - remove multiple log items from the AIL |
| * |
| * @xfs_trans_ail_delete_bulk takes an array of log items that all need to |
| * removed from the AIL. The caller is already holding the AIL lock, and done |
| * all the checks necessary to ensure the items passed in via @log_items are |
| * ready for deletion. This includes checking that the items are in the AIL. |
| * |
| * For each log item to be removed, unlink it from the AIL, clear the IN_AIL |
| * flag from the item and reset the item's lsn to 0. If we remove the first |
| * item in the AIL, update the log tail to match the new minimum LSN in the |
| * AIL. |
| * |
| * This function will not drop the AIL lock until all items are removed from |
| * the AIL to minimise the amount of lock traffic on the AIL. This does not |
| * greatly increase the AIL hold time, but does significantly reduce the amount |
| * of traffic on the lock, especially during IO completion. |
| * |
| * This function must be called with the AIL lock held. The lock is dropped |
| * before returning. |
| */ |
| void |
| xfs_trans_ail_delete_bulk( |
| struct xfs_ail *ailp, |
| struct xfs_log_item **log_items, |
| int nr_items) __releases(ailp->xa_lock) |
| { |
| xfs_log_item_t *mlip; |
| xfs_lsn_t tail_lsn; |
| int mlip_changed = 0; |
| int i; |
| |
| mlip = xfs_ail_min(ailp); |
| |
| for (i = 0; i < nr_items; i++) { |
| struct xfs_log_item *lip = log_items[i]; |
| if (!(lip->li_flags & XFS_LI_IN_AIL)) { |
| struct xfs_mount *mp = ailp->xa_mount; |
| |
| spin_unlock(&ailp->xa_lock); |
| if (!XFS_FORCED_SHUTDOWN(mp)) { |
| xfs_alert_tag(mp, XFS_PTAG_AILDELETE, |
| "%s: attempting to delete a log item that is not in the AIL", |
| __func__); |
| xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE); |
| } |
| return; |
| } |
| |
| xfs_ail_delete(ailp, lip); |
| lip->li_flags &= ~XFS_LI_IN_AIL; |
| lip->li_lsn = 0; |
| if (mlip == lip) |
| mlip_changed = 1; |
| } |
| |
| if (!mlip_changed) { |
| spin_unlock(&ailp->xa_lock); |
| return; |
| } |
| |
| /* |
| * It is not safe to access mlip after the AIL lock is dropped, so we |
| * must get a copy of li_lsn before we do so. This is especially |
| * important on 32-bit platforms where accessing and updating 64-bit |
| * values like li_lsn is not atomic. It is possible we've emptied the |
| * AIL here, so if that is the case, pass an LSN of 0 to the tail move. |
| */ |
| mlip = xfs_ail_min(ailp); |
| tail_lsn = mlip ? mlip->li_lsn : 0; |
| spin_unlock(&ailp->xa_lock); |
| xfs_log_move_tail(ailp->xa_mount, tail_lsn); |
| } |
| |
| /* |
| * The active item list (AIL) is a doubly linked list of log |
| * items sorted by ascending lsn. The base of the list is |
| * a forw/back pointer pair embedded in the xfs mount structure. |
| * The base is initialized with both pointers pointing to the |
| * base. This case always needs to be distinguished, because |
| * the base has no lsn to look at. We almost always insert |
| * at the end of the list, so on inserts we search from the |
| * end of the list to find where the new item belongs. |
| */ |
| |
| /* |
| * Initialize the doubly linked list to point only to itself. |
| */ |
| int |
| xfs_trans_ail_init( |
| xfs_mount_t *mp) |
| { |
| struct xfs_ail *ailp; |
| |
| ailp = kmem_zalloc(sizeof(struct xfs_ail), KM_MAYFAIL); |
| if (!ailp) |
| return ENOMEM; |
| |
| ailp->xa_mount = mp; |
| INIT_LIST_HEAD(&ailp->xa_ail); |
| spin_lock_init(&ailp->xa_lock); |
| INIT_DELAYED_WORK(&ailp->xa_work, xfs_ail_worker); |
| mp->m_ail = ailp; |
| return 0; |
| } |
| |
| void |
| xfs_trans_ail_destroy( |
| xfs_mount_t *mp) |
| { |
| struct xfs_ail *ailp = mp->m_ail; |
| |
| cancel_delayed_work_sync(&ailp->xa_work); |
| kmem_free(ailp); |
| } |