}
/*
+ * 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;
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);
*/
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;
/*
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) {
*/
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
*/
tout += 10;
}
-out:
*last_lsn = last_pushed_lsn;
return tout;
} /* xfsaild_push */
* 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.
*/
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);
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);
*/
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);
}
xfs_mount_t *mp)
{
struct xfs_ail *ailp;
+ int error;
ailp = kmem_zalloc(sizeof(struct xfs_ail), KM_MAYFAIL);
if (!ailp)
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
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff