diff options
Diffstat (limited to 'fs/xfs/xfs_trans_ail.c')
| -rw-r--r-- | fs/xfs/xfs_trans_ail.c | 1088 |
1 files changed, 651 insertions, 437 deletions
diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c index 19ab24af1c1..cb0f3a84cc6 100644 --- a/fs/xfs/xfs_trans_ail.c +++ b/fs/xfs/xfs_trans_ail.c @@ -1,5 +1,6 @@ /* * 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 @@ -17,565 +18,778 @@ */ #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_log_format.h" +#include "xfs_trans_resv.h" #include "xfs_sb.h" -#include "xfs_dir.h" -#include "xfs_dmapi.h" +#include "xfs_ag.h" #include "xfs_mount.h" +#include "xfs_trans.h" #include "xfs_trans_priv.h" +#include "xfs_trace.h" #include "xfs_error.h" - -STATIC void xfs_ail_insert(xfs_ail_entry_t *, xfs_log_item_t *); -STATIC xfs_log_item_t * xfs_ail_delete(xfs_ail_entry_t *, xfs_log_item_t *); -STATIC xfs_log_item_t * xfs_ail_min(xfs_ail_entry_t *); -STATIC xfs_log_item_t * xfs_ail_next(xfs_ail_entry_t *, xfs_log_item_t *); +#include "xfs_log.h" #ifdef DEBUG -STATIC void xfs_ail_check(xfs_ail_entry_t *); -#else -#define xfs_ail_check(a) +/* + * 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); + + +} +#else /* !DEBUG */ +#define xfs_ail_check(a,l) #endif /* DEBUG */ +/* + * 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); +} /* - * 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. + * 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. + * 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_trans_tail_ail( - xfs_mount_t *mp) +xfs_ail_min_lsn( + struct xfs_ail *ailp) { - xfs_lsn_t lsn; + xfs_lsn_t lsn = 0; xfs_log_item_t *lip; - SPLDECL(s); - AIL_LOCK(mp,s); - lip = xfs_ail_min(&(mp->m_ail)); - if (lip == NULL) { - lsn = (xfs_lsn_t)0; - } else { + spin_lock(&ailp->xa_lock); + lip = xfs_ail_min(ailp); + if (lip) lsn = lip->li_lsn; - } - AIL_UNLOCK(mp, s); + spin_unlock(&ailp->xa_lock); return lsn; } /* - * xfs_trans_push_ail - * - * 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 routine returns the lsn of the tail of the log. + * Return the maximum lsn held in the AIL, or zero if the AIL is empty. */ -xfs_lsn_t -xfs_trans_push_ail( - xfs_mount_t *mp, - xfs_lsn_t threshold_lsn) +static xfs_lsn_t +xfs_ail_max_lsn( + struct xfs_ail *ailp) { - xfs_lsn_t lsn; - xfs_log_item_t *lip; - int gen; - int restarts; - int lock_result; - int flush_log; - SPLDECL(s); + xfs_lsn_t lsn = 0; + xfs_log_item_t *lip; -#define XFS_TRANS_PUSH_AIL_RESTARTS 10 + spin_lock(&ailp->xa_lock); + lip = xfs_ail_max(ailp); + if (lip) + lsn = lip->li_lsn; + spin_unlock(&ailp->xa_lock); - AIL_LOCK(mp,s); - lip = xfs_trans_first_ail(mp, &gen); - if (lip == NULL || XFS_FORCED_SHUTDOWN(mp)) { - /* - * Just return if the AIL is empty. - */ - AIL_UNLOCK(mp, s); - return (xfs_lsn_t)0; - } + return lsn; +} - XFS_STATS_INC(xs_push_ail); +/* + * 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( + struct xfs_ail *ailp, + struct xfs_ail_cursor *cur) +{ + cur->item = NULL; + list_add_tail(&cur->list, &ailp->xa_cursors); +} - /* - * While the item we are looking at is below the given threshold - * try to flush it out. Make sure to limit the number of times - * we allow xfs_trans_next_ail() to restart scanning from the - * beginning of the list. 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 may give up before that if - * we realize that we've been holding the AIL_LOCK for 'too long', - * blocking interrupts. Currently, too long is < 500us roughly. - */ - flush_log = 0; - restarts = 0; - while (((restarts < XFS_TRANS_PUSH_AIL_RESTARTS) && - (XFS_LSN_CMP(lip->li_lsn, threshold_lsn) < 0))) { - /* - * 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. Since we unlock the AIL while we flush the - * item, the next routine may start over again at the - * the beginning of the list if anything has changed. - * That is what the generation count is for. - * - * 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); - switch (lock_result) { - case XFS_ITEM_SUCCESS: - AIL_UNLOCK(mp, s); - XFS_STATS_INC(xs_push_ail_success); - IOP_PUSH(lip); - AIL_LOCK(mp,s); - break; +/* + * 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( + struct xfs_ail *ailp, + struct xfs_ail_cursor *cur) +{ + struct xfs_log_item *lip = cur->item; - case XFS_ITEM_PUSHBUF: - AIL_UNLOCK(mp, s); - XFS_STATS_INC(xs_push_ail_pushbuf); -#ifdef XFSRACEDEBUG - delay_for_intr(); - delay(300); -#endif - ASSERT(lip->li_ops->iop_pushbuf); - ASSERT(lip); - IOP_PUSHBUF(lip); - AIL_LOCK(mp,s); - break; + if ((__psint_t)lip & 1) + lip = xfs_ail_min(ailp); + if (lip) + cur->item = xfs_ail_next(ailp, lip); + return lip; +} - case XFS_ITEM_PINNED: - XFS_STATS_INC(xs_push_ail_pinned); - flush_log = 1; - break; +/* + * 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_cursor *cur) +{ + cur->item = NULL; + list_del_init(&cur->list); +} - case XFS_ITEM_LOCKED: - XFS_STATS_INC(xs_push_ail_locked); - break; +/* + * 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( + struct xfs_ail *ailp, + struct xfs_log_item *lip) +{ + struct xfs_ail_cursor *cur; - case XFS_ITEM_FLUSHING: - XFS_STATS_INC(xs_push_ail_flushing); - break; + list_for_each_entry(cur, &ailp->xa_cursors, list) { + if (cur->item == lip) + cur->item = (struct xfs_log_item *) + ((__psint_t)cur->item | 1); + } +} - default: - ASSERT(0); - break; - } +/* + * 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( + struct xfs_ail *ailp, + struct xfs_ail_cursor *cur, + xfs_lsn_t lsn) +{ + xfs_log_item_t *lip; - lip = xfs_trans_next_ail(mp, lip, &gen, &restarts); - if (lip == NULL) { - break; - } - if (XFS_FORCED_SHUTDOWN(mp)) { - /* - * Just return if we shut down during the last try. - */ - AIL_UNLOCK(mp, s); - return (xfs_lsn_t)0; - } + xfs_trans_ail_cursor_init(ailp, cur); + if (lsn == 0) { + lip = xfs_ail_min(ailp); + goto out; } - 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. - */ - AIL_UNLOCK(mp, s); - XFS_STATS_INC(xs_push_ail_flush); - xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE); - AIL_LOCK(mp, s); + list_for_each_entry(lip, &ailp->xa_ail, li_ail) { + if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0) + goto out; } + return NULL; - lip = xfs_ail_min(&(mp->m_ail)); - if (lip == NULL) { - lsn = (xfs_lsn_t)0; - } else { - lsn = lip->li_lsn; - } +out: + if (lip) + cur->item = xfs_ail_next(ailp, lip); + return lip; +} - AIL_UNLOCK(mp, s); - return lsn; -} /* xfs_trans_push_ail */ +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; +} +/* + * 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( + 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; +} /* - * 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(). + * 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. This should not be called with an empty list. */ -void -xfs_trans_unlocked_item( - xfs_mount_t *mp, - xfs_log_item_t *lip) +static void +xfs_ail_splice( + struct xfs_ail *ailp, + struct xfs_ail_cursor *cur, + struct list_head *list, + xfs_lsn_t lsn) { - xfs_log_item_t *min_lip; + struct xfs_log_item *lip; + + ASSERT(!list_empty(list)); /* - * 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. + * 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->li_flags & XFS_LI_IN_AIL) || - XFS_FORCED_SHUTDOWN(mp)) { - return; - } + lip = cur ? cur->item : NULL; + if (!lip || (__psint_t) lip & 1) + lip = __xfs_trans_ail_cursor_last(ailp, lsn); /* - * 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. + * 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. */ - min_lip = xfs_ail_min(&mp->m_ail); - - if (min_lip == lip) - xfs_log_move_tail(mp, 1); -} /* xfs_trans_unlocked_item */ + if (cur) + cur->item = list_entry(list->prev, struct xfs_log_item, li_ail); + /* + * 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 (lip) + list_splice(list, &lip->li_ail); + else + list_splice(list, &ailp->xa_ail); +} /* - * Update the position of the item in the AIL with the new - * lsn. If it is not yet in the AIL, add it. Otherwise, move - * it to its new position by removing it and re-adding it. - * - * Wakeup anyone with an lsn less than the item's lsn. If the 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, so the caller must pass in the - * cookie returned by AIL_LOCK. + * Delete the given item from the AIL. Return a pointer to the item. */ -void -xfs_trans_update_ail( - xfs_mount_t *mp, - xfs_log_item_t *lip, - xfs_lsn_t lsn, - unsigned long s) +static void +xfs_ail_delete( + struct xfs_ail *ailp, + xfs_log_item_t *lip) { - xfs_ail_entry_t *ailp; - xfs_log_item_t *dlip=NULL; - xfs_log_item_t *mlip; /* ptr to minimum lip */ + xfs_ail_check(ailp, lip); + list_del(&lip->li_ail); + xfs_trans_ail_cursor_clear(ailp, lip); +} - ailp = &(mp->m_ail); - mlip = xfs_ail_min(ailp); +static long +xfsaild_push( + struct xfs_ail *ailp) +{ + xfs_mount_t *mp = ailp->xa_mount; + struct xfs_ail_cursor cur; + xfs_log_item_t *lip; + xfs_lsn_t lsn; + xfs_lsn_t target; + long tout; + int stuck = 0; + int flushing = 0; + int count = 0; - if (lip->li_flags & XFS_LI_IN_AIL) { - dlip = xfs_ail_delete(ailp, lip); - ASSERT(dlip == lip); - } else { - lip->li_flags |= XFS_LI_IN_AIL; + /* + * If we encountered pinned items or did not finish writing out all + * buffers the last time we ran, force the log first and wait for it + * before pushing again. + */ + if (ailp->xa_log_flush && ailp->xa_last_pushed_lsn == 0 && + (!list_empty_careful(&ailp->xa_buf_list) || + xfs_ail_min_lsn(ailp))) { + ailp->xa_log_flush = 0; + + XFS_STATS_INC(xs_push_ail_flush); + xfs_log_force(mp, XFS_LOG_SYNC); } - lip->li_lsn = lsn; + spin_lock(&ailp->xa_lock); - xfs_ail_insert(ailp, lip); - mp->m_ail_gen++; + /* barrier matches the xa_target update in xfs_ail_push() */ + smp_rmb(); + target = ailp->xa_target; + ailp->xa_target_prev = target; - if (mlip == dlip) { - mlip = xfs_ail_min(&(mp->m_ail)); - AIL_UNLOCK(mp, s); - xfs_log_move_tail(mp, mlip->li_lsn); - } else { - AIL_UNLOCK(mp, s); + lip = xfs_trans_ail_cursor_first(ailp, &cur, ailp->xa_last_pushed_lsn); + if (!lip) { + /* + * If the AIL is empty or our push has reached the end we are + * done now. + */ + xfs_trans_ail_cursor_done(&cur); + spin_unlock(&ailp->xa_lock); + goto out_done; } + XFS_STATS_INC(xs_push_ail); -} /* xfs_trans_update_ail */ + lsn = lip->li_lsn; + while ((XFS_LSN_CMP(lip->li_lsn, target) <= 0)) { + int lock_result; -/* - * Delete the given item from the AIL. It must already be in - * the AIL. - * - * Wakeup anyone with an lsn less than item's lsn. If the item - * we delete in the AIL is the minimum one, update the tail lsn in the - * log manager. - * - * Clear the IN_AIL flag from the item, reset its lsn to 0, and - * bump 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, so the caller must pass in the - * cookie returned by AIL_LOCK. - */ -void -xfs_trans_delete_ail( - xfs_mount_t *mp, - xfs_log_item_t *lip, - unsigned long s) -{ - xfs_ail_entry_t *ailp; - xfs_log_item_t *dlip; - xfs_log_item_t *mlip; + /* + * Note that iop_push may unlock and reacquire the AIL lock. We + * rely on the AIL cursor implementation to be able to deal with + * the dropped lock. + */ + lock_result = lip->li_ops->iop_push(lip, &ailp->xa_buf_list); + switch (lock_result) { + case XFS_ITEM_SUCCESS: + XFS_STATS_INC(xs_push_ail_success); + trace_xfs_ail_push(lip); - if (lip->li_flags & XFS_LI_IN_AIL) { - ailp = &(mp->m_ail); - mlip = xfs_ail_min(ailp); - dlip = xfs_ail_delete(ailp, lip); - ASSERT(dlip == lip); + ailp->xa_last_pushed_lsn = lsn; + break; + case XFS_ITEM_FLUSHING: + /* + * The item or its backing buffer is already beeing + * flushed. The typical reason for that is that an + * inode buffer is locked because we already pushed the + * updates to it as part of inode clustering. + * + * We do not want to to stop flushing just because lots + * of items are already beeing flushed, but we need to + * re-try the flushing relatively soon if most of the + * AIL is beeing flushed. + */ + XFS_STATS_INC(xs_push_ail_flushing); + trace_xfs_ail_flushing(lip); - lip->li_flags &= ~XFS_LI_IN_AIL; - lip->li_lsn = 0; - mp->m_ail_gen++; + flushing++; + ailp->xa_last_pushed_lsn = lsn; + break; - if (mlip == dlip) { - mlip = xfs_ail_min(&(mp->m_ail)); - AIL_UNLOCK(mp, s); - xfs_log_move_tail(mp, (mlip ? mlip->li_lsn : 0)); - } else { - AIL_UNLOCK(mp, s); + case XFS_ITEM_PINNED: + XFS_STATS_INC(xs_push_ail_pinned); + trace_xfs_ail_pinned(lip); + + stuck++; + ailp->xa_log_flush++; + break; + case XFS_ITEM_LOCKED: + XFS_STATS_INC(xs_push_ail_locked); + trace_xfs_ail_locked(lip); + + stuck++; + break; + default: + ASSERT(0); + break; } - } - else { + + count++; + /* - * If the file system is not being shutdown, we are in - * serious trouble if we get to this stage. + * 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 (XFS_FORCED_SHUTDOWN(mp)) - AIL_UNLOCK(mp, s); - else { - xfs_cmn_err(XFS_PTAG_AILDELETE, CE_ALERT, mp, - "xfs_trans_delete_ail: attempting to delete a log item that is not in the AIL"); - AIL_UNLOCK(mp, s); - xfs_force_shutdown(mp, XFS_CORRUPT_INCORE); - } + 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(&cur); + spin_unlock(&ailp->xa_lock); + if (xfs_buf_delwri_submit_nowait(&ailp->xa_buf_list)) + ailp->xa_log_flush++; + if (!count || XFS_LSN_CMP(lsn, target) >= 0) { +out_done: + /* + * We reached the target or the AIL is empty, 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 + flushing) * 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 + * 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; + } else { + /* + * Assume we have more work to do in a short while. + */ + tout = 10; + } -/* - * Return the item in the AIL with the smallest lsn. - * Return the current tree generation number for use - * in calls to xfs_trans_next_ail(). - */ -xfs_log_item_t * -xfs_trans_first_ail( - xfs_mount_t *mp, - int *gen) + return tout; +} + +static int +xfsaild( + void *data) { - xfs_log_item_t *lip; + struct xfs_ail *ailp = data; + long tout = 0; /* milliseconds */ - lip = xfs_ail_min(&(mp->m_ail)); - *gen = (int)mp->m_ail_gen; + current->flags |= PF_MEMALLOC; - return (lip); -} + while (!kthread_should_stop()) { + if (tout && tout <= 20) + __set_current_state(TASK_KILLABLE); + else + __set_current_state(TASK_INTERRUPTIBLE); -/* - * 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. - */ -xfs_log_item_t * -xfs_trans_next_ail( - xfs_mount_t *mp, - xfs_log_item_t *lip, - int *gen, - int *restarts) -{ - xfs_log_item_t *nlip; + spin_lock(&ailp->xa_lock); - ASSERT(mp && lip && gen); - if (mp->m_ail_gen == *gen) { - nlip = xfs_ail_next(&(mp->m_ail), lip); - } else { - nlip = xfs_ail_min(&(mp->m_ail)); - *gen = (int)mp->m_ail_gen; - if (restarts != NULL) { - XFS_STATS_INC(xs_push_ail_restarts); - (*restarts)++; + /* + * Idle if the AIL is empty and we are not racing with a target + * update. We check the AIL after we set the task to a sleep + * state to guarantee that we either catch an xa_target update + * or that a wake_up resets the state to TASK_RUNNING. + * Otherwise, we run the risk of sleeping indefinitely. + * + * The barrier matches the xa_target update in xfs_ail_push(). + */ + smp_rmb(); + if (!xfs_ail_min(ailp) && + ailp->xa_target == ailp->xa_target_prev) { + spin_unlock(&ailp->xa_lock); + schedule(); + tout = 0; + continue; } - } + spin_unlock(&ailp->xa_lock); - return (nlip); -} + if (tout) + schedule_timeout(msecs_to_jiffies(tout)); + __set_current_state(TASK_RUNNING); -/* - * 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. - */ + try_to_freeze(); -/* - * Initialize the doubly linked list to point only to itself. - */ -void -xfs_trans_ail_init( - xfs_mount_t *mp) -{ - mp->m_ail.ail_forw = (xfs_log_item_t*)&(mp->m_ail); - mp->m_ail.ail_back = (xfs_log_item_t*)&(mp->m_ail); + tout = xfsaild_push(ailp); + } + + return 0; } /* - * Insert the given log item into the AIL. - * 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. + * 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. */ -STATIC void -xfs_ail_insert( - xfs_ail_entry_t *base, - xfs_log_item_t *lip) -/* ARGSUSED */ +void +xfs_ail_push( + struct xfs_ail *ailp, + xfs_lsn_t threshold_lsn) { - xfs_log_item_t *next_lip; + 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; /* - * If the list is empty, just insert the item. + * Ensure that the new target is noticed in push code before it clears + * the XFS_AIL_PUSHING_BIT. */ - if (base->ail_back == (xfs_log_item_t*)base) { - base->ail_forw = lip; - base->ail_back = lip; - lip->li_ail.ail_forw = (xfs_log_item_t*)base; - lip->li_ail.ail_back = (xfs_log_item_t*)base; - return; - } + smp_wmb(); + xfs_trans_ail_copy_lsn(ailp, &ailp->xa_target, &threshold_lsn); + smp_wmb(); - next_lip = base->ail_back; - while ((next_lip != (xfs_log_item_t*)base) && - (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) > 0)) { - next_lip = next_lip->li_ail.ail_back; - } - ASSERT((next_lip == (xfs_log_item_t*)base) || - (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) <= 0)); - lip->li_ail.ail_forw = next_lip->li_ail.ail_forw; - lip->li_ail.ail_back = next_lip; - next_lip->li_ail.ail_forw = lip; - lip->li_ail.ail_forw->li_ail.ail_back = lip; - - xfs_ail_check(base); - return; + wake_up_process(ailp->xa_task); } /* - * Delete the given item from the AIL. Return a pointer to the item. + * Push out all items in the AIL immediately */ -/*ARGSUSED*/ -STATIC xfs_log_item_t * -xfs_ail_delete( - xfs_ail_entry_t *base, - xfs_log_item_t *lip) -/* ARGSUSED */ +void +xfs_ail_push_all( + struct xfs_ail *ailp) { - lip->li_ail.ail_forw->li_ail.ail_back = lip->li_ail.ail_back; - lip->li_ail.ail_back->li_ail.ail_forw = lip->li_ail.ail_forw; - lip->li_ail.ail_forw = NULL; - lip->li_ail.ail_back = NULL; + xfs_lsn_t threshold_lsn = xfs_ail_max_lsn(ailp); - xfs_ail_check(base); - return lip; + if (threshold_lsn) + xfs_ail_push(ailp, threshold_lsn); } /* - * Return a pointer to the first item in the AIL. - * If the AIL is empty, then return NULL. + * Push out all items in the AIL immediately and wait until the AIL is empty. */ -STATIC xfs_log_item_t * -xfs_ail_min( - xfs_ail_entry_t *base) -/* ARGSUSED */ +void +xfs_ail_push_all_sync( + struct xfs_ail *ailp) { - register xfs_log_item_t *forw = base->ail_forw; - if (forw == (xfs_log_item_t*)base) { - return NULL; + struct xfs_log_item *lip; + DEFINE_WAIT(wait); + + spin_lock(&ailp->xa_lock); + while ((lip = xfs_ail_max(ailp)) != NULL) { + prepare_to_wait(&ailp->xa_empty, &wait, TASK_UNINTERRUPTIBLE); + ailp->xa_target = lip->li_lsn; + wake_up_process(ailp->xa_task); + spin_unlock(&ailp->xa_lock); + schedule(); + spin_lock(&ailp->xa_lock); } - return forw; + spin_unlock(&ailp->xa_lock); + + finish_wait(&ailp->xa_empty, &wait); } /* - * 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. + * 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. */ -STATIC xfs_log_item_t * -xfs_ail_next( - xfs_ail_entry_t *base, - xfs_log_item_t *lip) -/* ARGSUSED */ +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) { - if (lip->li_ail.ail_forw == (xfs_log_item_t*)base) { - return NULL; + xfs_log_item_t *mlip; + int mlip_changed = 0; + 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++) { + 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; + + trace_xfs_ail_move(lip, lip->li_lsn, lsn); + xfs_ail_delete(ailp, lip); + if (mlip == lip) + mlip_changed = 1; + } else { + lip->li_flags |= XFS_LI_IN_AIL; + trace_xfs_ail_insert(lip, 0, lsn); + } + lip->li_lsn = lsn; + list_add(&lip->li_ail, &tmp); } - return lip->li_ail.ail_forw; + if (!list_empty(&tmp)) + xfs_ail_splice(ailp, cur, &tmp, lsn); + + if (mlip_changed) { + if (!XFS_FORCED_SHUTDOWN(ailp->xa_mount)) + xlog_assign_tail_lsn_locked(ailp->xa_mount); + spin_unlock(&ailp->xa_lock); + + xfs_log_space_wake(ailp->xa_mount); + } else { + spin_unlock(&ailp->xa_lock); + } } -#ifdef DEBUG /* - * Check that the list is sorted as it should be. + * 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. */ -STATIC void -xfs_ail_check( - xfs_ail_entry_t *base) +void +xfs_trans_ail_delete_bulk( + struct xfs_ail *ailp, + struct xfs_log_item **log_items, + int nr_items, + int shutdown_type) __releases(ailp->xa_lock) { - xfs_log_item_t *lip; - xfs_log_item_t *prev_lip; + xfs_log_item_t *mlip; + int mlip_changed = 0; + int i; - lip = base->ail_forw; - if (lip == (xfs_log_item_t*)base) { - /* - * Make sure the pointers are correct when the list - * is empty. - */ - ASSERT(base->ail_back == (xfs_log_item_t*)base); - return; - } + mlip = xfs_ail_min(ailp); - /* - * Walk the list checking forward and backward pointers, - * lsn ordering, and that every entry has the XFS_LI_IN_AIL - * flag set. - */ - prev_lip = (xfs_log_item_t*)base; - while (lip != (xfs_log_item_t*)base) { - if (prev_lip != (xfs_log_item_t*)base) { - ASSERT(prev_lip->li_ail.ail_forw == lip); - ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0); + 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_type); + } + return; } - ASSERT(lip->li_ail.ail_back == prev_lip); - ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0); - prev_lip = lip; - lip = lip->li_ail.ail_forw; + + trace_xfs_ail_delete(lip, mlip->li_lsn, lip->li_lsn); + 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) { + if (!XFS_FORCED_SHUTDOWN(ailp->xa_mount)) + xlog_assign_tail_lsn_locked(ailp->xa_mount); + if (list_empty(&ailp->xa_ail)) + wake_up_all(&ailp->xa_empty); + spin_unlock(&ailp->xa_lock); + + xfs_log_space_wake(ailp->xa_mount); + } else { + spin_unlock(&ailp->xa_lock); } - ASSERT(lip == (xfs_log_item_t*)base); - ASSERT(base->ail_back == prev_lip); } -#endif /* DEBUG */ + +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); + INIT_LIST_HEAD(&ailp->xa_cursors); + spin_lock_init(&ailp->xa_lock); + INIT_LIST_HEAD(&ailp->xa_buf_list); + init_waitqueue_head(&ailp->xa_empty); + + ailp->xa_task = kthread_run(xfsaild, ailp, "xfsaild/%s", + ailp->xa_mount->m_fsname); + if (IS_ERR(ailp->xa_task)) + goto out_free_ailp; + + mp->m_ail = ailp; + return 0; + +out_free_ailp: + kmem_free(ailp); + return ENOMEM; +} + +void +xfs_trans_ail_destroy( + xfs_mount_t *mp) +{ + struct xfs_ail *ailp = mp->m_ail; + + kthread_stop(ailp->xa_task); + kmem_free(ailp); +} |