tmp_suning_uos_patched/fs/xfs/xfs_trans_priv.h
David Chinner 7b2e2a31f5 [XFS] Allow 64 bit machines to avoid the AIL lock during flushes
When copying lsn's from the log item to the inode or dquot flush lsn, we
currently grab the AIL lock. We do this because the LSN is a 64 bit
quantity and it needs to be read atomically. The lock is used to guarantee
atomicity for 32 bit platforms.

Make the LSN copying a small function, and make the function used
conditional on BITS_PER_LONG so that 64 bit machines don't need to take
the AIL lock in these places.

SGI-PV: 988143

SGI-Modid: xfs-linux-melb:xfs-kern:32349a

Signed-off-by: David Chinner <david@fromorbit.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 17:39:12 +11:00

133 lines
4.1 KiB
C

/*
* 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
*/
#ifndef __XFS_TRANS_PRIV_H__
#define __XFS_TRANS_PRIV_H__
struct xfs_log_item;
struct xfs_log_item_desc;
struct xfs_mount;
struct xfs_trans;
/*
* From xfs_trans_item.c
*/
struct xfs_log_item_desc *xfs_trans_add_item(struct xfs_trans *,
struct xfs_log_item *);
void xfs_trans_free_item(struct xfs_trans *,
struct xfs_log_item_desc *);
struct xfs_log_item_desc *xfs_trans_find_item(struct xfs_trans *,
struct xfs_log_item *);
struct xfs_log_item_desc *xfs_trans_first_item(struct xfs_trans *);
struct xfs_log_item_desc *xfs_trans_next_item(struct xfs_trans *,
struct xfs_log_item_desc *);
void xfs_trans_free_items(struct xfs_trans *, int);
void xfs_trans_unlock_items(struct xfs_trans *,
xfs_lsn_t);
void xfs_trans_free_busy(xfs_trans_t *tp);
xfs_log_busy_slot_t *xfs_trans_add_busy(xfs_trans_t *tp,
xfs_agnumber_t ag,
xfs_extlen_t idx);
/*
* AIL traversal cursor.
*
* Rather than using a generation number for detecting changes in the ail, use
* a cursor that is protected by the ail lock. The aild cursor exists in the
* struct xfs_ail, but other traversals can declare it on the stack and link it
* to the ail list.
*
* When an object is deleted from or moved int the AIL, the cursor list is
* searched to see if the object is a designated cursor item. If it is, it is
* deleted from the cursor so that the next time the cursor is used traversal
* will return to the start.
*
* This means a traversal colliding with a removal will cause a restart of the
* list scan, rather than any insertion or deletion anywhere in the list. The
* low bit of the item pointer is set if the cursor has been invalidated so
* that we can tell the difference between invalidation and reaching the end
* of the list to trigger traversal restarts.
*/
struct xfs_ail_cursor {
struct xfs_ail_cursor *next;
struct xfs_log_item *item;
};
/*
* Private AIL structures.
*
* Eventually we need to drive the locking in here as well.
*/
struct xfs_ail {
struct xfs_mount *xa_mount;
struct list_head xa_ail;
uint xa_gen;
struct task_struct *xa_task;
xfs_lsn_t xa_target;
struct xfs_ail_cursor xa_cursors;
};
/*
* From xfs_trans_ail.c
*/
void xfs_trans_update_ail(struct xfs_mount *mp,
struct xfs_log_item *lip, xfs_lsn_t lsn)
__releases(mp->m_ail_lock);
void xfs_trans_delete_ail(struct xfs_mount *mp,
struct xfs_log_item *lip)
__releases(mp->m_ail_lock);
xfs_lsn_t xfs_trans_ail_tail(struct xfs_ail *ailp);
struct xfs_log_item *xfs_trans_ail_cursor_first(struct xfs_ail *ailp,
struct xfs_ail_cursor *cur,
xfs_lsn_t lsn);
struct xfs_log_item *xfs_trans_ail_cursor_next(struct xfs_ail *ailp,
struct xfs_ail_cursor *cur);
void xfs_trans_ail_cursor_done(struct xfs_ail *ailp,
struct xfs_ail_cursor *cur);
long xfsaild_push(struct xfs_ail *, xfs_lsn_t *);
void xfsaild_wakeup(struct xfs_ail *, xfs_lsn_t);
int xfsaild_start(struct xfs_ail *);
void xfsaild_stop(struct xfs_ail *);
#if BITS_PER_LONG != 64
static inline void
xfs_trans_ail_copy_lsn(
struct xfs_ail *ailp,
xfs_lsn_t *dst,
xfs_lsn_t *src)
{
ASSERT(sizeof(xfs_lsn_t) == 8); /* don't lock if it shrinks */
spin_lock(&ailp->xa_mount->m_ail_lock);
*dst = *src;
spin_unlock(&ailp->xa_mount->m_ail_lock);
}
#else
static inline void
xfs_trans_ail_copy_lsn(
struct xfs_ail *ailp,
xfs_lsn_t *dst,
xfs_lsn_t *src)
{
ASSERT(sizeof(xfs_lsn_t) == 8);
*dst = *src;
}
#endif
#endif /* __XFS_TRANS_PRIV_H__ */