/* * 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_dmapi.h" #include "xfs_mount.h" #include "xfs_trans_priv.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 *); #ifdef DEBUG STATIC void xfs_ail_check(xfs_ail_entry_t *); #else #define xfs_ail_check(a) #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; SPLDECL(s); AIL_LOCK(mp,s); lip = xfs_ail_min(&(mp->m_ail)); if (lip == NULL) { lsn = (xfs_lsn_t)0; } else { lsn = lip->li_lsn; } AIL_UNLOCK(mp, s); 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. */ xfs_lsn_t xfs_trans_push_ail( xfs_mount_t *mp, xfs_lsn_t threshold_lsn) { xfs_lsn_t lsn; xfs_log_item_t *lip; int gen; int restarts; int lock_result; int flush_log; SPLDECL(s); #define XFS_TRANS_PUSH_AIL_RESTARTS 1000 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; } XFS_STATS_INC(xs_push_ail); /* * 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; 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; case XFS_ITEM_PINNED: XFS_STATS_INC(xs_push_ail_pinned); flush_log = 1; break; case XFS_ITEM_LOCKED: XFS_STATS_INC(xs_push_ail_locked); break; case XFS_ITEM_FLUSHING: XFS_STATS_INC(xs_push_ail_flushing); break; default: ASSERT(0); break; } 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; } } 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); } lip = xfs_ail_min(&(mp->m_ail)); if (lip == NULL) { lsn = (xfs_lsn_t)0; } else { lsn = lip->li_lsn; } AIL_UNLOCK(mp, s); return lsn; } /* xfs_trans_push_ail */ /* * 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, so the caller must pass in the * cookie returned by AIL_LOCK. */ void xfs_trans_update_ail( xfs_mount_t *mp, xfs_log_item_t *lip, xfs_lsn_t lsn, unsigned long s) __releases(mp->m_ail_lock) { xfs_ail_entry_t *ailp; xfs_log_item_t *dlip=NULL; xfs_log_item_t *mlip; /* ptr to minimum lip */ ailp = &(mp->m_ail); mlip = xfs_ail_min(ailp); 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; } lip->li_lsn = lsn; xfs_ail_insert(ailp, lip); mp->m_ail_gen++; 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); } } /* 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, 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) __releases(mp->m_ail_lock) { xfs_ail_entry_t *ailp; xfs_log_item_t *dlip; xfs_log_item_t *mlip; 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); lip->li_flags &= ~XFS_LI_IN_AIL; lip->li_lsn = 0; mp->m_ail_gen++; 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); } } 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)) AIL_UNLOCK(mp, s); else { xfs_cmn_err(XFS_PTAG_AILDELETE, CE_ALERT, mp, "%s: attempting to delete a log item that is not in the AIL", __FUNCTION__); AIL_UNLOCK(mp, s); 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_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_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)++; } } 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. */ 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); } /* * 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( xfs_ail_entry_t *base, xfs_log_item_t *lip) /* ARGSUSED */ { xfs_log_item_t *next_lip; /* * If the list is empty, just insert the item. */ 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; } 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; } /* * Delete the given item from the AIL. Return a pointer to the item. */ /*ARGSUSED*/ STATIC xfs_log_item_t * xfs_ail_delete( xfs_ail_entry_t *base, xfs_log_item_t *lip) /* ARGSUSED */ { 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_ail_check(base); 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( xfs_ail_entry_t *base) /* ARGSUSED */ { register xfs_log_item_t *forw = base->ail_forw; if (forw == (xfs_log_item_t*)base) { return NULL; } return forw; } /* * 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( xfs_ail_entry_t *base, xfs_log_item_t *lip) /* ARGSUSED */ { if (lip->li_ail.ail_forw == (xfs_log_item_t*)base) { return NULL; } return lip->li_ail.ail_forw; } #ifdef DEBUG /* * Check that the list is sorted as it should be. */ STATIC void xfs_ail_check( xfs_ail_entry_t *base) { xfs_log_item_t *lip; xfs_log_item_t *prev_lip; 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; } /* * 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); } 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; } ASSERT(lip == (xfs_log_item_t*)base); ASSERT(base->ail_back == prev_lip); } #endif /* DEBUG */