linux/fs/xfs/libxfs/xfs_defer.h
Brian Foster b277c37f43 xfs: bypass final dfops roll in trans commit path
Once xfs_defer_finish() has completed all deferred operations, it
checks the dirty state of the transaction and rolls it once more to
return a clean transaction for the caller. This primarily to cover
the case where repeated xfs_defer_finish() calls are made in a loop
and we need to make sure that the caller starts the next iteration
with a clean transaction. Otherwise we risk transaction reservation
overrun.

This final transaction roll is not required in the transaction
commit path, however, because the transaction is immediately
committed and freed after dfops completion. Refactor the final roll
into a separate helper such that we can avoid it in the transaction
commit path.  Lift the dfops reset as well so dfops remains valid
until after the last call to xfs_defer_trans_roll(). The reset is
also unnecessary in the transaction commit path because the
transaction is about to complete.

This eliminates unnecessary regrants of transactions where the
associated transaction roll can be replaced by a transaction commit.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Bill O'Donnell <billodo@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2018-07-26 10:15:16 -07:00

78 lines
2.9 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2016 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <darrick.wong@oracle.com>
*/
#ifndef __XFS_DEFER_H__
#define __XFS_DEFER_H__
struct xfs_defer_op_type;
struct xfs_defer_ops;
/*
* Save a log intent item and a list of extents, so that we can replay
* whatever action had to happen to the extent list and file the log done
* item.
*/
struct xfs_defer_pending {
const struct xfs_defer_op_type *dfp_type; /* function pointers */
struct list_head dfp_list; /* pending items */
void *dfp_intent; /* log intent item */
void *dfp_done; /* log done item */
struct list_head dfp_work; /* work items */
unsigned int dfp_count; /* # extent items */
};
/*
* Header for deferred operation list.
*
* dop_low is used by the allocator to activate the lowspace algorithm -
* when free space is running low the extent allocator may choose to
* allocate an extent from an AG without leaving sufficient space for
* a btree split when inserting the new extent. In this case the allocator
* will enable the lowspace algorithm which is supposed to allow further
* allocations (such as btree splits and newroots) to allocate from
* sequential AGs. In order to avoid locking AGs out of order the lowspace
* algorithm will start searching for free space from AG 0. If the correct
* transaction reservations have been made then this algorithm will eventually
* find all the space it needs.
*/
enum xfs_defer_ops_type {
XFS_DEFER_OPS_TYPE_BMAP,
XFS_DEFER_OPS_TYPE_REFCOUNT,
XFS_DEFER_OPS_TYPE_RMAP,
XFS_DEFER_OPS_TYPE_FREE,
XFS_DEFER_OPS_TYPE_AGFL_FREE,
XFS_DEFER_OPS_TYPE_MAX,
};
void xfs_defer_add(struct xfs_defer_ops *dop, enum xfs_defer_ops_type type,
struct list_head *h);
int xfs_defer_finish_noroll(struct xfs_trans **tp);
int xfs_defer_finish(struct xfs_trans **tp);
void __xfs_defer_cancel(struct xfs_defer_ops *dop);
void xfs_defer_init(struct xfs_trans *tp, struct xfs_defer_ops *dop);
bool xfs_defer_has_unfinished_work(struct xfs_defer_ops *dop);
int xfs_defer_ijoin(struct xfs_defer_ops *dop, struct xfs_inode *ip);
int xfs_defer_bjoin(struct xfs_defer_ops *dop, struct xfs_buf *bp);
void xfs_defer_move(struct xfs_defer_ops *dst, struct xfs_defer_ops *src);
/* Description of a deferred type. */
struct xfs_defer_op_type {
enum xfs_defer_ops_type type;
unsigned int max_items;
void (*abort_intent)(void *);
void *(*create_done)(struct xfs_trans *, void *, unsigned int);
int (*finish_item)(struct xfs_trans *, struct xfs_defer_ops *,
struct list_head *, void *, void **);
void (*finish_cleanup)(struct xfs_trans *, void *, int);
void (*cancel_item)(struct list_head *);
int (*diff_items)(void *, struct list_head *, struct list_head *);
void *(*create_intent)(struct xfs_trans *, uint);
void (*log_item)(struct xfs_trans *, void *, struct list_head *);
};
void xfs_defer_init_op_type(const struct xfs_defer_op_type *type);
#endif /* __XFS_DEFER_H__ */