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linux/fs/xfs/xfs_trans.h
Darrick J. Wong 4e919af782 xfs: periodically relog deferred intent items 
There's a subtle design flaw in the deferred log item code that can lead
to pinning the log tail.  Taking up the defer ops chain examples from
the previous commit, we can get trapped in sequences like this:

Caller hands us a transaction t0 with D0-D3 attached.  The defer ops
chain will look like the following if the transaction rolls succeed:

t1: D0(t0), D1(t0), D2(t0), D3(t0)
t2: d4(t1), d5(t1), D1(t0), D2(t0), D3(t0)
t3: d5(t1), D1(t0), D2(t0), D3(t0)
...
t9: d9(t7), D3(t0)
t10: D3(t0)
t11: d10(t10), d11(t10)
t12: d11(t10)

In transaction 9, we finish d9 and try to roll to t10 while holding onto
an intent item for D3 that we logged in t0.

The previous commit changed the order in which we place new defer ops in
the defer ops processing chain to reduce the maximum chain length.  Now
make xfs_defer_finish_noroll capable of relogging the entire chain
periodically so that we can always move the log tail forward.  Most
chains will never get relogged, except for operations that generate very
long chains (large extents containing many blocks with different sharing
levels) or are on filesystems with small logs and a lot of ongoing
metadata updates.

Callers are now required to ensure that the transaction reservation is
large enough to handle logging done items and new intent items for the
maximum possible chain length.  Most callers are careful to keep the
chain lengths low, so the overhead should be minimal.

The decision to relog an intent item is made based on whether the intent
was logged in a previous checkpoint, since there's no point in relogging
an intent into the same checkpoint.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
2020-10-07 08:40:28 -07:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
* All Rights Reserved.
*/
#ifndef __XFS_TRANS_H__
#define __XFS_TRANS_H__
/* kernel only transaction subsystem defines */
struct xfs_buf;
struct xfs_buftarg;
struct xfs_efd_log_item;
struct xfs_efi_log_item;
struct xfs_inode;
struct xfs_item_ops;
struct xfs_log_iovec;
struct xfs_mount;
struct xfs_trans;
struct xfs_trans_res;
struct xfs_dquot_acct;
struct xfs_rud_log_item;
struct xfs_rui_log_item;
struct xfs_btree_cur;
struct xfs_cui_log_item;
struct xfs_cud_log_item;
struct xfs_bui_log_item;
struct xfs_bud_log_item;
struct xfs_log_item {
struct list_head li_ail; /* AIL pointers */
struct list_head li_trans; /* transaction list */
xfs_lsn_t li_lsn; /* last on-disk lsn */
struct xfs_mount *li_mountp; /* ptr to fs mount */
struct xfs_ail *li_ailp; /* ptr to AIL */
uint li_type; /* item type */
unsigned long li_flags; /* misc flags */
struct xfs_buf *li_buf; /* real buffer pointer */
struct list_head li_bio_list; /* buffer item list */
const struct xfs_item_ops *li_ops; /* function list */
/* delayed logging */
struct list_head li_cil; /* CIL pointers */
struct xfs_log_vec *li_lv; /* active log vector */
struct xfs_log_vec *li_lv_shadow; /* standby vector */
xfs_lsn_t li_seq; /* CIL commit seq */
};
/*
* li_flags use the (set/test/clear)_bit atomic interfaces because updates can
* race with each other and we don't want to have to use the AIL lock to
* serialise all updates.
*/
#define XFS_LI_IN_AIL 0
#define XFS_LI_ABORTED 1
#define XFS_LI_FAILED 2
#define XFS_LI_DIRTY 3 /* log item dirty in transaction */
#define XFS_LI_FLAGS \
{ (1 << XFS_LI_IN_AIL), "IN_AIL" }, \
{ (1 << XFS_LI_ABORTED), "ABORTED" }, \
{ (1 << XFS_LI_FAILED), "FAILED" }, \
{ (1 << XFS_LI_DIRTY), "DIRTY" }
struct xfs_item_ops {
unsigned flags;
void (*iop_size)(struct xfs_log_item *, int *, int *);
void (*iop_format)(struct xfs_log_item *, struct xfs_log_vec *);
void (*iop_pin)(struct xfs_log_item *);
void (*iop_unpin)(struct xfs_log_item *, int remove);
uint (*iop_push)(struct xfs_log_item *, struct list_head *);
void (*iop_committing)(struct xfs_log_item *, xfs_lsn_t commit_lsn);
void (*iop_release)(struct xfs_log_item *);
xfs_lsn_t (*iop_committed)(struct xfs_log_item *, xfs_lsn_t);
int (*iop_recover)(struct xfs_log_item *lip,
struct list_head *capture_list);
bool (*iop_match)(struct xfs_log_item *item, uint64_t id);
struct xfs_log_item *(*iop_relog)(struct xfs_log_item *intent,
struct xfs_trans *tp);
};
/* Is this log item a deferred action intent? */
static inline bool
xlog_item_is_intent(struct xfs_log_item *lip)
{
return lip->li_ops->iop_recover != NULL &&
lip->li_ops->iop_match != NULL;
}
/* Is this a log intent-done item? */
static inline bool
xlog_item_is_intent_done(struct xfs_log_item *lip)
{
return lip->li_ops->iop_unpin == NULL &&
lip->li_ops->iop_push == NULL;
}
/*
* Release the log item as soon as committed. This is for items just logging
* intents that never need to be written back in place.
*/
#define XFS_ITEM_RELEASE_WHEN_COMMITTED (1 << 0)
void xfs_log_item_init(struct xfs_mount *mp, struct xfs_log_item *item,
int type, const struct xfs_item_ops *ops);
/*
* Return values for the iop_push() routines.
*/
#define XFS_ITEM_SUCCESS 0
#define XFS_ITEM_PINNED 1
#define XFS_ITEM_LOCKED 2
#define XFS_ITEM_FLUSHING 3
/*
* Deferred operation item relogging limits.
*/
#define XFS_DEFER_OPS_NR_INODES 2 /* join up to two inodes */
#define XFS_DEFER_OPS_NR_BUFS 2 /* join up to two buffers */
/*
* This is the structure maintained for every active transaction.
*/
typedef struct xfs_trans {
unsigned int t_magic; /* magic number */
unsigned int t_log_res; /* amt of log space resvd */
unsigned int t_log_count; /* count for perm log res */
unsigned int t_blk_res; /* # of blocks resvd */
unsigned int t_blk_res_used; /* # of resvd blocks used */
unsigned int t_rtx_res; /* # of rt extents resvd */
unsigned int t_rtx_res_used; /* # of resvd rt extents used */
unsigned int t_flags; /* misc flags */
xfs_fsblock_t t_firstblock; /* first block allocated */
struct xlog_ticket *t_ticket; /* log mgr ticket */
struct xfs_mount *t_mountp; /* ptr to fs mount struct */
struct xfs_dquot_acct *t_dqinfo; /* acctg info for dquots */
int64_t t_icount_delta; /* superblock icount change */
int64_t t_ifree_delta; /* superblock ifree change */
int64_t t_fdblocks_delta; /* superblock fdblocks chg */
int64_t t_res_fdblocks_delta; /* on-disk only chg */
int64_t t_frextents_delta;/* superblock freextents chg*/
int64_t t_res_frextents_delta; /* on-disk only chg */
#if defined(DEBUG) || defined(XFS_WARN)
int64_t t_ag_freeblks_delta; /* debugging counter */
int64_t t_ag_flist_delta; /* debugging counter */
int64_t t_ag_btree_delta; /* debugging counter */
#endif
int64_t t_dblocks_delta;/* superblock dblocks change */
int64_t t_agcount_delta;/* superblock agcount change */
int64_t t_imaxpct_delta;/* superblock imaxpct change */
int64_t t_rextsize_delta;/* superblock rextsize chg */
int64_t t_rbmblocks_delta;/* superblock rbmblocks chg */
int64_t t_rblocks_delta;/* superblock rblocks change */
int64_t t_rextents_delta;/* superblocks rextents chg */
int64_t t_rextslog_delta;/* superblocks rextslog chg */
struct list_head t_items; /* log item descriptors */
struct list_head t_busy; /* list of busy extents */
struct list_head t_dfops; /* deferred operations */
unsigned long t_pflags; /* saved process flags state */
} xfs_trans_t;
/*
* XFS transaction mechanism exported interfaces that are
* actually macros.
*/
#define xfs_trans_set_sync(tp) ((tp)->t_flags |= XFS_TRANS_SYNC)
#if defined(DEBUG) || defined(XFS_WARN)
#define xfs_trans_agblocks_delta(tp, d) ((tp)->t_ag_freeblks_delta += (int64_t)d)
#define xfs_trans_agflist_delta(tp, d) ((tp)->t_ag_flist_delta += (int64_t)d)
#define xfs_trans_agbtree_delta(tp, d) ((tp)->t_ag_btree_delta += (int64_t)d)
#else
#define xfs_trans_agblocks_delta(tp, d)
#define xfs_trans_agflist_delta(tp, d)
#define xfs_trans_agbtree_delta(tp, d)
#endif
/*
* XFS transaction mechanism exported interfaces.
*/
int xfs_trans_alloc(struct xfs_mount *mp, struct xfs_trans_res *resp,
uint blocks, uint rtextents, uint flags,
struct xfs_trans **tpp);
int xfs_trans_alloc_empty(struct xfs_mount *mp,
struct xfs_trans **tpp);
void xfs_trans_mod_sb(xfs_trans_t *, uint, int64_t);
int xfs_trans_get_buf_map(struct xfs_trans *tp, struct xfs_buftarg *target,
struct xfs_buf_map *map, int nmaps, xfs_buf_flags_t flags,
struct xfs_buf **bpp);
static inline int
xfs_trans_get_buf(
struct xfs_trans *tp,
struct xfs_buftarg *target,
xfs_daddr_t blkno,
int numblks,
uint flags,
struct xfs_buf **bpp)
{
DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
return xfs_trans_get_buf_map(tp, target, &map, 1, flags, bpp);
}
int xfs_trans_read_buf_map(struct xfs_mount *mp,
struct xfs_trans *tp,
struct xfs_buftarg *target,
struct xfs_buf_map *map, int nmaps,
xfs_buf_flags_t flags,
struct xfs_buf **bpp,
const struct xfs_buf_ops *ops);
static inline int
xfs_trans_read_buf(
struct xfs_mount *mp,
struct xfs_trans *tp,
struct xfs_buftarg *target,
xfs_daddr_t blkno,
int numblks,
xfs_buf_flags_t flags,
struct xfs_buf **bpp,
const struct xfs_buf_ops *ops)
{
DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
return xfs_trans_read_buf_map(mp, tp, target, &map, 1,
flags, bpp, ops);
}
struct xfs_buf *xfs_trans_getsb(struct xfs_trans *);
void xfs_trans_brelse(xfs_trans_t *, struct xfs_buf *);
void xfs_trans_bjoin(xfs_trans_t *, struct xfs_buf *);
void xfs_trans_bhold(xfs_trans_t *, struct xfs_buf *);
void xfs_trans_bhold_release(xfs_trans_t *, struct xfs_buf *);
void xfs_trans_binval(xfs_trans_t *, struct xfs_buf *);
void xfs_trans_inode_buf(xfs_trans_t *, struct xfs_buf *);
void xfs_trans_stale_inode_buf(xfs_trans_t *, struct xfs_buf *);
bool xfs_trans_ordered_buf(xfs_trans_t *, struct xfs_buf *);
void xfs_trans_dquot_buf(xfs_trans_t *, struct xfs_buf *, uint);
void xfs_trans_inode_alloc_buf(xfs_trans_t *, struct xfs_buf *);
void xfs_trans_ichgtime(struct xfs_trans *, struct xfs_inode *, int);
void xfs_trans_ijoin(struct xfs_trans *, struct xfs_inode *, uint);
void xfs_trans_log_buf(struct xfs_trans *, struct xfs_buf *, uint,
uint);
void xfs_trans_dirty_buf(struct xfs_trans *, struct xfs_buf *);
bool xfs_trans_buf_is_dirty(struct xfs_buf *bp);
void xfs_trans_log_inode(xfs_trans_t *, struct xfs_inode *, uint);
int xfs_trans_commit(struct xfs_trans *);
int xfs_trans_roll(struct xfs_trans **);
int xfs_trans_roll_inode(struct xfs_trans **, struct xfs_inode *);
void xfs_trans_cancel(xfs_trans_t *);
int xfs_trans_ail_init(struct xfs_mount *);
void xfs_trans_ail_destroy(struct xfs_mount *);
void xfs_trans_buf_set_type(struct xfs_trans *, struct xfs_buf *,
enum xfs_blft);
void xfs_trans_buf_copy_type(struct xfs_buf *dst_bp,
struct xfs_buf *src_bp);
extern kmem_zone_t *xfs_trans_zone;
static inline struct xfs_log_item *
xfs_trans_item_relog(
struct xfs_log_item *lip,
struct xfs_trans *tp)
{
return lip->li_ops->iop_relog(lip, tp);
}
#endif /* __XFS_TRANS_H__ */
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