/* * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc. * 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_dmapi.h" #include "xfs_mount.h" #include "xfs_trans_priv.h" #include "xfs_error.h" STATIC void xfs_ail_insert(struct xfs_ail *, xfs_log_item_t *); STATIC xfs_log_item_t * xfs_ail_delete(struct xfs_ail *, xfs_log_item_t *); STATIC xfs_log_item_t * xfs_ail_min(struct xfs_ail *); STATIC xfs_log_item_t * xfs_ail_next(struct xfs_ail *, xfs_log_item_t *); #ifdef DEBUG STATIC void xfs_ail_check(struct xfs_ail *, xfs_log_item_t *); #else #define xfs_ail_check(a,l) #endif /* DEBUG */ /* * 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_trans_tail_ail( xfs_mount_t *mp) { xfs_lsn_t lsn; xfs_log_item_t *lip; spin_lock(&mp->m_ail_lock); lip = xfs_ail_min(mp->m_ail); if (lip == NULL) { lsn = (xfs_lsn_t)0; } else { lsn = lip->li_lsn; } spin_unlock(&mp->m_ail_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 push is run asynchronously in a separate thread, so we return the tail * of the log right now instead of the tail after the push. This means we will * either continue right away, or we will sleep waiting on the async thread to * do it's work. * * 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_trans_push_ail( xfs_mount_t *mp, xfs_lsn_t threshold_lsn) { xfs_log_item_t *lip; lip = xfs_ail_min(mp->m_ail); if (lip && !XFS_FORCED_SHUTDOWN(mp)) { if (XFS_LSN_CMP(threshold_lsn, mp->m_ail->xa_target) > 0) xfsaild_wakeup(mp->m_ail, threshold_lsn); } } /* * Return the item in the AIL with the current lsn. * Return the current tree generation number for use * in calls to xfs_trans_next_ail(). */ STATIC xfs_log_item_t * xfs_trans_first_push_ail( xfs_mount_t *mp, int *gen, xfs_lsn_t lsn) { xfs_log_item_t *lip; lip = xfs_ail_min(mp->m_ail); *gen = (int)mp->m_ail->xa_gen; 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) return lip; } return NULL; } /* * Function that does the work of pushing on the AIL */ long xfsaild_push( struct xfs_ail *ailp, xfs_lsn_t *last_lsn) { long tout = 1000; /* milliseconds */ xfs_lsn_t last_pushed_lsn = *last_lsn; 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 spin_lock(&mp->m_ail_lock); lip = xfs_trans_first_push_ail(mp, &gen, *last_lsn); if (!lip || XFS_FORCED_SHUTDOWN(mp)) { /* * AIL is empty or our push has reached the end. */ spin_unlock(&mp->m_ail_lock); last_pushed_lsn = 0; goto out; } 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. */ tout = 10; lsn = lip->li_lsn; flush_log = stuck = count = restarts = 0; 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(&mp->m_ail_lock); switch (lock_result) { case XFS_ITEM_SUCCESS: XFS_STATS_INC(xs_push_ail_success); IOP_PUSH(lip); last_pushed_lsn = lsn; break; case XFS_ITEM_PUSHBUF: XFS_STATS_INC(xs_push_ail_pushbuf); IOP_PUSHBUF(lip); last_pushed_lsn = lsn; 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); last_pushed_lsn = lsn; stuck++; break; case XFS_ITEM_FLUSHING: XFS_STATS_INC(xs_push_ail_flushing); last_pushed_lsn = lsn; stuck++; break; default: ASSERT(0); break; } spin_lock(&mp->m_ail_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_next_ail(mp, lip, &gen, &restarts); if (lip == NULL) break; if (restarts > XFS_TRANS_PUSH_AIL_RESTARTS) break; lsn = lip->li_lsn; } spin_unlock(&mp->m_ail_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, (xfs_lsn_t)0, XFS_LOG_FORCE); } if (!count) { /* We're past our target or empty, so idle */ tout = 1000; } 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 += 20; last_pushed_lsn = 0; } else if ((restarts > XFS_TRANS_PUSH_AIL_RESTARTS) || ((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 += 10; } out: *last_lsn = last_pushed_lsn; return tout; } /* xfsaild_push */ /* * 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( xfs_mount_t *mp, 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(mp)) { 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(mp->m_ail); if (min_lip == lip) xfs_log_move_tail(mp, 1); } /* xfs_trans_unlocked_item */ /* * 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. */ void xfs_trans_update_ail( xfs_mount_t *mp, xfs_log_item_t *lip, xfs_lsn_t lsn) __releases(mp->m_ail_lock) { xfs_log_item_t *dlip=NULL; xfs_log_item_t *mlip; /* ptr to minimum lip */ mlip = xfs_ail_min(mp->m_ail); if (lip->li_flags & XFS_LI_IN_AIL) { dlip = xfs_ail_delete(mp->m_ail, lip); ASSERT(dlip == lip); } 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); spin_unlock(&mp->m_ail_lock); xfs_log_move_tail(mp, mlip->li_lsn); } else { spin_unlock(&mp->m_ail_lock); } } /* xfs_trans_update_ail */ /* * 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. */ void xfs_trans_delete_ail( xfs_mount_t *mp, xfs_log_item_t *lip) __releases(mp->m_ail_lock) { xfs_log_item_t *dlip; xfs_log_item_t *mlip; if (lip->li_flags & XFS_LI_IN_AIL) { mlip = xfs_ail_min(mp->m_ail); dlip = xfs_ail_delete(mp->m_ail, lip); ASSERT(dlip == lip); 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); spin_unlock(&mp->m_ail_lock); xfs_log_move_tail(mp, (mlip ? mlip->li_lsn : 0)); } else { spin_unlock(&mp->m_ail_lock); } } else { /* * If the file system is not being shutdown, we are in * serious trouble if we get to this stage. */ if (XFS_FORCED_SHUTDOWN(mp)) spin_unlock(&mp->m_ail_lock); else { xfs_cmn_err(XFS_PTAG_AILDELETE, CE_ALERT, mp, "%s: attempting to delete a log item that is not in the AIL", __func__); spin_unlock(&mp->m_ail_lock); xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE); } } } /* * 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) { xfs_log_item_t *lip; lip = xfs_ail_min(mp->m_ail); *gen = (int)mp->m_ail->xa_gen; 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. */ 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; 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); } /* * 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); return xfsaild_start(ailp); } void xfs_trans_ail_destroy( xfs_mount_t *mp) { struct xfs_ail *ailp = mp->m_ail; xfsaild_stop(ailp); kmem_free(ailp); } /* * 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. */ STATIC void xfs_ail_insert( struct xfs_ail *ailp, xfs_log_item_t *lip) /* ARGSUSED */ { xfs_log_item_t *next_lip; /* * If the list is empty, just insert the item. */ if (list_empty(&ailp->xa_ail)) { list_add(&lip->li_ail, &ailp->xa_ail); return; } list_for_each_entry_reverse(next_lip, &ailp->xa_ail, li_ail) { if (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) <= 0) break; } ASSERT((&next_lip->li_ail == &ailp->xa_ail) || (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) <= 0)); list_add(&lip->li_ail, &next_lip->li_ail); xfs_ail_check(ailp, lip); return; } /* * Delete the given item from the AIL. Return a pointer to the item. */ /*ARGSUSED*/ STATIC xfs_log_item_t * xfs_ail_delete( struct xfs_ail *ailp, xfs_log_item_t *lip) /* ARGSUSED */ { xfs_ail_check(ailp, lip); list_del(&lip->li_ail); return lip; } /* * 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) /* ARGSUSED */ { 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 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) /* ARGSUSED */ { if (lip->li_ail.next == &ailp->xa_ail) return NULL; return list_first_entry(&lip->li_ail, xfs_log_item_t, li_ail); } #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 */ } #endif /* DEBUG */