diff options
Diffstat (limited to 'fs/xfs/xfs_trans_ail.c')
| -rw-r--r-- | fs/xfs/xfs_trans_ail.c | 207 |
1 files changed, 151 insertions, 56 deletions
diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c index db72b52cd42..7b8bfcf1d3d 100644 --- a/fs/xfs/xfs_trans_ail.c +++ b/fs/xfs/xfs_trans_ail.c @@ -99,26 +99,137 @@ xfs_trans_push_ail( } /* + * 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. + */ +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. + */ +STATIC 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; +} + +/* + * 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); + } +} + +/* + * 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 alway 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); +} + +/* * 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) + struct xfs_ail *ailp, + struct xfs_ail_cursor *cur, + xfs_lsn_t lsn) { - xfs_log_item_t *lip; + xfs_log_item_t *lip; - lip = xfs_ail_min(mp->m_ail); - *gen = (int)mp->m_ail->xa_gen; + lip = xfs_ail_min(ailp); + xfs_trans_ail_cursor_set(ailp, cur, lip); 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) + list_for_each_entry(lip, &ailp->xa_ail, li_ail) { + if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0) { + xfs_trans_ail_cursor_set(ailp, cur, lip); return lip; + } } return NULL; @@ -137,22 +248,21 @@ xfsaild_push( 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 + struct xfs_ail_cursor *cur = &ailp->xa_cursors; spin_lock(&mp->m_ail_lock); - lip = xfs_trans_first_push_ail(mp, &gen, *last_lsn); + xfs_trans_ail_cursor_init(ailp, cur); + lip = xfs_trans_first_push_ail(ailp, cur, *last_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(&mp->m_ail_lock); last_pushed_lsn = 0; - goto out; + return tout; } XFS_STATS_INC(xs_push_ail); @@ -170,7 +280,7 @@ xfsaild_push( */ tout = 10; lsn = lip->li_lsn; - flush_log = stuck = count = restarts = 0; + flush_log = stuck = count = 0; while ((XFS_LSN_CMP(lip->li_lsn, target) < 0)) { int lock_result; /* @@ -245,13 +355,12 @@ xfsaild_push( if (stuck > 100) break; - lip = xfs_trans_next_ail(mp, lip, &gen, &restarts); + lip = xfs_trans_ail_cursor_next(ailp, cur); if (lip == NULL) break; - if (restarts > XFS_TRANS_PUSH_AIL_RESTARTS) - break; lsn = lip->li_lsn; } + xfs_trans_ail_cursor_done(ailp, cur); spin_unlock(&mp->m_ail_lock); if (flush_log) { @@ -275,8 +384,7 @@ xfsaild_push( */ tout += 20; last_pushed_lsn = 0; - } else if ((restarts > XFS_TRANS_PUSH_AIL_RESTARTS) || - ((stuck * 100) / count > 90)) { + } 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 @@ -288,7 +396,6 @@ xfsaild_push( */ tout += 10; } -out: *last_lsn = last_pushed_lsn; return tout; } /* xfsaild_push */ @@ -348,9 +455,6 @@ xfs_trans_unlocked_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. */ @@ -368,14 +472,13 @@ xfs_trans_update_ail( if (lip->li_flags & XFS_LI_IN_AIL) { dlip = xfs_ail_delete(mp->m_ail, lip); ASSERT(dlip == lip); + xfs_trans_ail_cursor_clear(mp->m_ail, dlip); } 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); @@ -415,11 +518,11 @@ xfs_trans_delete_ail( mlip = xfs_ail_min(mp->m_ail); dlip = xfs_ail_delete(mp->m_ail, lip); ASSERT(dlip == lip); + xfs_trans_ail_cursor_clear(mp->m_ail, dlip); 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); @@ -455,46 +558,29 @@ xfs_trans_delete_ail( */ xfs_log_item_t * xfs_trans_first_ail( - xfs_mount_t *mp, - int *gen) + struct xfs_mount *mp, + struct xfs_ail_cursor *cur) { - xfs_log_item_t *lip; + xfs_log_item_t *lip; + struct xfs_ail *ailp = mp->m_ail; - lip = xfs_ail_min(mp->m_ail); - *gen = (int)mp->m_ail->xa_gen; + lip = xfs_ail_min(ailp); + xfs_trans_ail_cursor_set(ailp, cur, lip); 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. + * Grab the next item in the AIL from the cursor passed in. */ xfs_log_item_t * xfs_trans_next_ail( - xfs_mount_t *mp, - xfs_log_item_t *lip, - int *gen, - int *restarts) + struct xfs_mount *mp, + struct xfs_ail_cursor *cur) { - 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)++; - } - } + struct xfs_ail *ailp = mp->m_ail; - return (nlip); + return xfs_trans_ail_cursor_next(ailp, cur); } @@ -517,6 +603,7 @@ xfs_trans_ail_init( xfs_mount_t *mp) { struct xfs_ail *ailp; + int error; ailp = kmem_zalloc(sizeof(struct xfs_ail), KM_MAYFAIL); if (!ailp) @@ -524,7 +611,15 @@ xfs_trans_ail_init( ailp->xa_mount = mp; INIT_LIST_HEAD(&ailp->xa_ail); - return xfsaild_start(ailp); + error = xfsaild_start(ailp); + if (error) + goto out_free_ailp; + mp->m_ail = ailp; + return 0; + +out_free_ailp: + kmem_free(ailp); + return error; } void |