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xfsaild idle mode logic currently leads to a couple hangs:
1.) If xfsaild is rescheduled in during an incremental scan
(i.e., tout != 0) and the target has been updated since
the previous run, we can hit the new target and go into
idle mode with a still populated ail.
2.) A wake up is only issued when the target is pushed forward.
The wake up can race with xfsaild if it is currently in the
process of entering idle mode, causing future wake up
events to be lost.
These hangs have been reproduced and verified as fixed by
running xfstests 273 in a loop on a slightly modified upstream
kernel. The kernel is modified to re-enable idle mode as
previously implemented (when count == 0) and with a revert of
commit 670ce93f, which includes performance improvements that
make this harder to reproduce.
The solution, the algorithm for which has been outlined by
Dave Chinner, is to modify xfsaild to enter idle mode only when
the ail is empty and the push target has not been moved forward
since the last push.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
149 lines
4.5 KiB
C
149 lines
4.5 KiB
C
/*
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* Copyright (c) 2000,2002,2005 Silicon Graphics, Inc.
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* All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef __XFS_TRANS_PRIV_H__
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#define __XFS_TRANS_PRIV_H__
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struct xfs_log_item;
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struct xfs_log_item_desc;
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struct xfs_mount;
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struct xfs_trans;
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struct xfs_ail;
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struct xfs_log_vec;
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void xfs_trans_add_item(struct xfs_trans *, struct xfs_log_item *);
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void xfs_trans_del_item(struct xfs_log_item *);
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void xfs_trans_free_items(struct xfs_trans *tp, xfs_lsn_t commit_lsn,
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int flags);
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void xfs_trans_unreserve_and_mod_sb(struct xfs_trans *tp);
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void xfs_trans_committed_bulk(struct xfs_ail *ailp, struct xfs_log_vec *lv,
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xfs_lsn_t commit_lsn, int aborted);
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/*
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* AIL traversal cursor.
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*
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* Rather than using a generation number for detecting changes in the ail, use
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* a cursor that is protected by the ail lock. The aild cursor exists in the
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* struct xfs_ail, but other traversals can declare it on the stack and link it
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* to the ail list.
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*
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* When an object is deleted from or moved int the AIL, the cursor list is
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* searched to see if the object is a designated cursor item. If it is, it is
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* deleted from the cursor so that the next time the cursor is used traversal
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* will return to the start.
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*
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* This means a traversal colliding with a removal will cause a restart of the
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* list scan, rather than any insertion or deletion anywhere in the list. The
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* low bit of the item pointer is set if the cursor has been invalidated so
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* that we can tell the difference between invalidation and reaching the end
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* of the list to trigger traversal restarts.
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*/
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struct xfs_ail_cursor {
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struct list_head list;
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struct xfs_log_item *item;
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};
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/*
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* Private AIL structures.
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*
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* Eventually we need to drive the locking in here as well.
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*/
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struct xfs_ail {
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struct xfs_mount *xa_mount;
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struct task_struct *xa_task;
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struct list_head xa_ail;
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xfs_lsn_t xa_target;
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xfs_lsn_t xa_target_prev;
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struct list_head xa_cursors;
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spinlock_t xa_lock;
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xfs_lsn_t xa_last_pushed_lsn;
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int xa_log_flush;
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struct list_head xa_buf_list;
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wait_queue_head_t xa_empty;
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};
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/*
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* From xfs_trans_ail.c
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*/
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void xfs_trans_ail_update_bulk(struct xfs_ail *ailp,
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struct xfs_ail_cursor *cur,
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struct xfs_log_item **log_items, int nr_items,
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xfs_lsn_t lsn) __releases(ailp->xa_lock);
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static inline void
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xfs_trans_ail_update(
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struct xfs_ail *ailp,
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struct xfs_log_item *lip,
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xfs_lsn_t lsn) __releases(ailp->xa_lock)
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{
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xfs_trans_ail_update_bulk(ailp, NULL, &lip, 1, lsn);
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}
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void xfs_trans_ail_delete_bulk(struct xfs_ail *ailp,
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struct xfs_log_item **log_items, int nr_items,
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int shutdown_type)
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__releases(ailp->xa_lock);
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static inline void
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xfs_trans_ail_delete(
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struct xfs_ail *ailp,
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xfs_log_item_t *lip,
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int shutdown_type) __releases(ailp->xa_lock)
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{
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xfs_trans_ail_delete_bulk(ailp, &lip, 1, shutdown_type);
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}
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void xfs_ail_push(struct xfs_ail *, xfs_lsn_t);
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void xfs_ail_push_all(struct xfs_ail *);
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void xfs_ail_push_all_sync(struct xfs_ail *);
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struct xfs_log_item *xfs_ail_min(struct xfs_ail *ailp);
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xfs_lsn_t xfs_ail_min_lsn(struct xfs_ail *ailp);
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struct xfs_log_item * xfs_trans_ail_cursor_first(struct xfs_ail *ailp,
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struct xfs_ail_cursor *cur,
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xfs_lsn_t lsn);
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struct xfs_log_item * xfs_trans_ail_cursor_last(struct xfs_ail *ailp,
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struct xfs_ail_cursor *cur,
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xfs_lsn_t lsn);
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struct xfs_log_item * xfs_trans_ail_cursor_next(struct xfs_ail *ailp,
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struct xfs_ail_cursor *cur);
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void xfs_trans_ail_cursor_done(struct xfs_ail *ailp,
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struct xfs_ail_cursor *cur);
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#if BITS_PER_LONG != 64
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static inline void
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xfs_trans_ail_copy_lsn(
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struct xfs_ail *ailp,
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xfs_lsn_t *dst,
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xfs_lsn_t *src)
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{
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ASSERT(sizeof(xfs_lsn_t) == 8); /* don't lock if it shrinks */
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spin_lock(&ailp->xa_lock);
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*dst = *src;
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spin_unlock(&ailp->xa_lock);
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}
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#else
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static inline void
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xfs_trans_ail_copy_lsn(
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struct xfs_ail *ailp,
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xfs_lsn_t *dst,
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xfs_lsn_t *src)
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{
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ASSERT(sizeof(xfs_lsn_t) == 8);
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*dst = *src;
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}
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#endif
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#endif /* __XFS_TRANS_PRIV_H__ */
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