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e98c414f9a
Currently we track log item descriptor belonging to a transaction using a complex opencoded chunk allocator. This code has been there since day one and seems to work around the lack of an efficient slab allocator. This patch replaces it with dynamically allocated log item descriptors from a dedicated slab pool, linked to the transaction by a linked list. This allows to greatly simplify the log item descriptor tracking to the point where it's just a couple hundred lines in xfs_trans.c instead of a separate file. The external API has also been simplified while we're at it - the xfs_trans_add_item and xfs_trans_del_item functions to add/ delete items from a transaction have been simplified to the bare minium, and the xfs_trans_find_item function is replaced with a direct dereference of the li_desc field. All debug code walking the list of log items in a transaction is down to a simple list_for_each_entry. Note that we could easily use a singly linked list here instead of the double linked list from list.h as the fastpath only does deletion from sequential traversal. But given that we don't have one available as a library function yet I use the list.h functions for simplicity. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Dave Chinner <dchinner@redhat.com>
124 lines
3.8 KiB
C
124 lines
3.8 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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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_item_committed(struct xfs_log_item *lip,
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xfs_lsn_t commit_lsn, int aborted);
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void xfs_trans_unreserve_and_mod_sb(struct xfs_trans *tp);
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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 xfs_ail_cursor *next;
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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 list_head xa_ail;
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uint xa_gen;
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struct task_struct *xa_task;
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xfs_lsn_t xa_target;
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struct xfs_ail_cursor xa_cursors;
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spinlock_t xa_lock;
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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(struct xfs_ail *ailp,
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struct xfs_log_item *lip, xfs_lsn_t lsn)
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__releases(ailp->xa_lock);
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void xfs_trans_ail_delete(struct xfs_ail *ailp,
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struct xfs_log_item *lip)
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__releases(ailp->xa_lock);
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void xfs_trans_ail_push(struct xfs_ail *, xfs_lsn_t);
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void xfs_trans_unlocked_item(struct xfs_ail *,
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xfs_log_item_t *);
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xfs_lsn_t xfs_trans_ail_tail(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_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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long xfsaild_push(struct xfs_ail *, xfs_lsn_t *);
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void xfsaild_wakeup(struct xfs_ail *, xfs_lsn_t);
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int xfsaild_start(struct xfs_ail *);
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void xfsaild_stop(struct xfs_ail *);
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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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