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linux/fs/xfs/libxfs/xfs_ag.h
Darrick J. Wong d5c88131db xfs: allow queued AG intents to drain before scrubbing 
When a writer thread executes a chain of log intent items, the AG header
buffer locks will cycle during a transaction roll to get from one intent
item to the next in a chain.  Although scrub takes all AG header buffer
locks, this isn't sufficient to guard against scrub checking an AG while
that writer thread is in the middle of finishing a chain because there's
no higher level locking primitive guarding allocation groups.

When there's a collision, cross-referencing between data structures
(e.g. rmapbt and refcountbt) yields false corruption events; if repair
is running, this results in incorrect repairs, which is catastrophic.

Fix this by adding to the perag structure the count of active intents
and make scrub wait until it has both AG header buffer locks and the
intent counter reaches zero.

One quirk of the drain code is that deferred bmap updates also bump and
drop the intent counter.  A fundamental decision made during the design
phase of the reverse mapping feature is that updates to the rmapbt
records are always made by the same code that updates the primary
metadata.  In other words, callers of bmapi functions expect that the
bmapi functions will queue deferred rmap updates.

Some parts of the reflink code queue deferred refcount (CUI) and bmap
(BUI) updates in the same head transaction, but the deferred work
manager completely finishes the CUI before the BUI work is started.  As
a result, the CUI drops the intent count long before the deferred rmap
(RUI) update even has a chance to bump the intent count.  The only way
to keep the intent count elevated between the CUI and RUI is for the BUI
to bump the counter until the RUI has been created.

A second quirk of the intent drain code is that deferred work items must
increment the intent counter as soon as the work item is added to the
transaction.  When a BUI completes and queues an RUI, the RUI must
increment the counter before the BUI decrements it.  The only way to
accomplish this is to require that the counter be bumped as soon as the
deferred work item is created in memory.

In the next patches we'll improve on this facility, but this patch
provides the basic functionality.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
2023-04-11 18:59:58 -07:00

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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (c) 2018 Red Hat, Inc.
* All rights reserved.
*/
#ifndef __LIBXFS_AG_H
#define __LIBXFS_AG_H 1
struct xfs_mount;
struct xfs_trans;
struct xfs_perag;
/*
* Per-ag infrastructure
*/
/* per-AG block reservation data structures*/
struct xfs_ag_resv {
/* number of blocks originally reserved here */
xfs_extlen_t ar_orig_reserved;
/* number of blocks reserved here */
xfs_extlen_t ar_reserved;
/* number of blocks originally asked for */
xfs_extlen_t ar_asked;
};
/*
* Per-ag incore structure, copies of information in agf and agi, to improve the
* performance of allocation group selection.
*/
struct xfs_perag {
struct xfs_mount *pag_mount; /* owner filesystem */
xfs_agnumber_t pag_agno; /* AG this structure belongs to */
atomic_t pag_ref; /* passive reference count */
atomic_t pag_active_ref; /* active reference count */
wait_queue_head_t pag_active_wq;/* woken active_ref falls to zero */
unsigned long pag_opstate;
uint8_t pagf_levels[XFS_BTNUM_AGF];
/* # of levels in bno & cnt btree */
uint32_t pagf_flcount; /* count of blocks in freelist */
xfs_extlen_t pagf_freeblks; /* total free blocks */
xfs_extlen_t pagf_longest; /* longest free space */
uint32_t pagf_btreeblks; /* # of blocks held in AGF btrees */
xfs_agino_t pagi_freecount; /* number of free inodes */
xfs_agino_t pagi_count; /* number of allocated inodes */
/*
* Inode allocation search lookup optimisation.
* If the pagino matches, the search for new inodes
* doesn't need to search the near ones again straight away
*/
xfs_agino_t pagl_pagino;
xfs_agino_t pagl_leftrec;
xfs_agino_t pagl_rightrec;
int pagb_count; /* pagb slots in use */
uint8_t pagf_refcount_level; /* recount btree height */
/* Blocks reserved for all kinds of metadata. */
struct xfs_ag_resv pag_meta_resv;
/* Blocks reserved for the reverse mapping btree. */
struct xfs_ag_resv pag_rmapbt_resv;
/* for rcu-safe freeing */
struct rcu_head rcu_head;
/* Precalculated geometry info */
xfs_agblock_t block_count;
xfs_agblock_t min_block;
xfs_agino_t agino_min;
xfs_agino_t agino_max;
#ifdef __KERNEL__
/* -- kernel only structures below this line -- */
/*
* Bitsets of per-ag metadata that have been checked and/or are sick.
* Callers should hold pag_state_lock before accessing this field.
*/
uint16_t pag_checked;
uint16_t pag_sick;
spinlock_t pag_state_lock;
spinlock_t pagb_lock; /* lock for pagb_tree */
struct rb_root pagb_tree; /* ordered tree of busy extents */
unsigned int pagb_gen; /* generation count for pagb_tree */
wait_queue_head_t pagb_wait; /* woken when pagb_gen changes */
atomic_t pagf_fstrms; /* # of filestreams active in this AG */
spinlock_t pag_ici_lock; /* incore inode cache lock */
struct radix_tree_root pag_ici_root; /* incore inode cache root */
int pag_ici_reclaimable; /* reclaimable inodes */
unsigned long pag_ici_reclaim_cursor; /* reclaim restart point */
/* buffer cache index */
spinlock_t pag_buf_lock; /* lock for pag_buf_hash */
struct rhashtable pag_buf_hash;
/* background prealloc block trimming */
struct delayed_work pag_blockgc_work;
/*
* We use xfs_drain to track the number of deferred log intent items
* that have been queued (but not yet processed) so that waiters (e.g.
* scrub) will not lock resources when other threads are in the middle
* of processing a chain of intent items only to find momentary
* inconsistencies.
*/
struct xfs_defer_drain pag_intents_drain;
#endif /* __KERNEL__ */
};
/*
* Per-AG operational state. These are atomic flag bits.
*/
#define XFS_AGSTATE_AGF_INIT 0
#define XFS_AGSTATE_AGI_INIT 1
#define XFS_AGSTATE_PREFERS_METADATA 2
#define XFS_AGSTATE_ALLOWS_INODES 3
#define XFS_AGSTATE_AGFL_NEEDS_RESET 4
#define __XFS_AG_OPSTATE(name, NAME) \
static inline bool xfs_perag_ ## name (struct xfs_perag *pag) \
{ \
return test_bit(XFS_AGSTATE_ ## NAME, &pag->pag_opstate); \
}
__XFS_AG_OPSTATE(initialised_agf, AGF_INIT)
__XFS_AG_OPSTATE(initialised_agi, AGI_INIT)
__XFS_AG_OPSTATE(prefers_metadata, PREFERS_METADATA)
__XFS_AG_OPSTATE(allows_inodes, ALLOWS_INODES)
__XFS_AG_OPSTATE(agfl_needs_reset, AGFL_NEEDS_RESET)
int xfs_initialize_perag(struct xfs_mount *mp, xfs_agnumber_t agcount,
xfs_rfsblock_t dcount, xfs_agnumber_t *maxagi);
int xfs_initialize_perag_data(struct xfs_mount *mp, xfs_agnumber_t agno);
void xfs_free_perag(struct xfs_mount *mp);
/* Passive AG references */
struct xfs_perag *xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno);
struct xfs_perag *xfs_perag_get_tag(struct xfs_mount *mp, xfs_agnumber_t agno,
unsigned int tag);
struct xfs_perag *xfs_perag_hold(struct xfs_perag *pag);
void xfs_perag_put(struct xfs_perag *pag);
/* Active AG references */
struct xfs_perag *xfs_perag_grab(struct xfs_mount *, xfs_agnumber_t);
struct xfs_perag *xfs_perag_grab_tag(struct xfs_mount *, xfs_agnumber_t,
int tag);
void xfs_perag_rele(struct xfs_perag *pag);
/*
* Per-ag geometry infomation and validation
*/
xfs_agblock_t xfs_ag_block_count(struct xfs_mount *mp, xfs_agnumber_t agno);
void xfs_agino_range(struct xfs_mount *mp, xfs_agnumber_t agno,
xfs_agino_t *first, xfs_agino_t *last);
static inline bool
xfs_verify_agbno(struct xfs_perag *pag, xfs_agblock_t agbno)
{
if (agbno >= pag->block_count)
return false;
if (agbno <= pag->min_block)
return false;
return true;
}
static inline bool
xfs_verify_agbext(
struct xfs_perag *pag,
xfs_agblock_t agbno,
xfs_agblock_t len)
{
if (agbno + len <= agbno)
return false;
if (!xfs_verify_agbno(pag, agbno))
return false;
return xfs_verify_agbno(pag, agbno + len - 1);
}
/*
* Verify that an AG inode number pointer neither points outside the AG
* nor points at static metadata.
*/
static inline bool
xfs_verify_agino(struct xfs_perag *pag, xfs_agino_t agino)
{
if (agino < pag->agino_min)
return false;
if (agino > pag->agino_max)
return false;
return true;
}
/*
* Verify that an AG inode number pointer neither points outside the AG
* nor points at static metadata, or is NULLAGINO.
*/
static inline bool
xfs_verify_agino_or_null(struct xfs_perag *pag, xfs_agino_t agino)
{
if (agino == NULLAGINO)
return true;
return xfs_verify_agino(pag, agino);
}
static inline bool
xfs_ag_contains_log(struct xfs_mount *mp, xfs_agnumber_t agno)
{
return mp->m_sb.sb_logstart > 0 &&
agno == XFS_FSB_TO_AGNO(mp, mp->m_sb.sb_logstart);
}
/*
* Perag iteration APIs
*/
static inline struct xfs_perag *
xfs_perag_next(
struct xfs_perag *pag,
xfs_agnumber_t *agno,
xfs_agnumber_t end_agno)
{
struct xfs_mount *mp = pag->pag_mount;
*agno = pag->pag_agno + 1;
xfs_perag_rele(pag);
while (*agno <= end_agno) {
pag = xfs_perag_grab(mp, *agno);
if (pag)
return pag;
(*agno)++;
}
return NULL;
}
#define for_each_perag_range(mp, agno, end_agno, pag) \
for ((pag) = xfs_perag_grab((mp), (agno)); \
(pag) != NULL; \
(pag) = xfs_perag_next((pag), &(agno), (end_agno)))
#define for_each_perag_from(mp, agno, pag) \
for_each_perag_range((mp), (agno), (mp)->m_sb.sb_agcount - 1, (pag))
#define for_each_perag(mp, agno, pag) \
(agno) = 0; \
for_each_perag_from((mp), (agno), (pag))
#define for_each_perag_tag(mp, agno, pag, tag) \
for ((agno) = 0, (pag) = xfs_perag_grab_tag((mp), 0, (tag)); \
(pag) != NULL; \
(agno) = (pag)->pag_agno + 1, \
xfs_perag_rele(pag), \
(pag) = xfs_perag_grab_tag((mp), (agno), (tag)))
static inline struct xfs_perag *
xfs_perag_next_wrap(
struct xfs_perag *pag,
xfs_agnumber_t *agno,
xfs_agnumber_t stop_agno,
xfs_agnumber_t restart_agno,
xfs_agnumber_t wrap_agno)
{
struct xfs_mount *mp = pag->pag_mount;
*agno = pag->pag_agno + 1;
xfs_perag_rele(pag);
while (*agno != stop_agno) {
if (*agno >= wrap_agno) {
if (restart_agno >= stop_agno)
break;
*agno = restart_agno;
}
pag = xfs_perag_grab(mp, *agno);
if (pag)
return pag;
(*agno)++;
}
return NULL;
}
/*
* Iterate all AGs from start_agno through wrap_agno, then restart_agno through
* (start_agno - 1).
*/
#define for_each_perag_wrap_range(mp, start_agno, restart_agno, wrap_agno, agno, pag) \
for ((agno) = (start_agno), (pag) = xfs_perag_grab((mp), (agno)); \
(pag) != NULL; \
(pag) = xfs_perag_next_wrap((pag), &(agno), (start_agno), \
(restart_agno), (wrap_agno)))
/*
* Iterate all AGs from start_agno through wrap_agno, then 0 through
* (start_agno - 1).
*/
#define for_each_perag_wrap_at(mp, start_agno, wrap_agno, agno, pag) \
for_each_perag_wrap_range((mp), (start_agno), 0, (wrap_agno), (agno), (pag))
/*
* Iterate all AGs from start_agno through to the end of the filesystem, then 0
* through (start_agno - 1).
*/
#define for_each_perag_wrap(mp, start_agno, agno, pag) \
for_each_perag_wrap_at((mp), (start_agno), (mp)->m_sb.sb_agcount, \
(agno), (pag))
struct aghdr_init_data {
/* per ag data */
xfs_agblock_t agno; /* ag to init */
xfs_extlen_t agsize; /* new AG size */
struct list_head buffer_list; /* buffer writeback list */
xfs_rfsblock_t nfree; /* cumulative new free space */
/* per header data */
xfs_daddr_t daddr; /* header location */
size_t numblks; /* size of header */
xfs_btnum_t type; /* type of btree root block */
};
int xfs_ag_init_headers(struct xfs_mount *mp, struct aghdr_init_data *id);
int xfs_ag_shrink_space(struct xfs_perag *pag, struct xfs_trans **tpp,
xfs_extlen_t delta);
int xfs_ag_extend_space(struct xfs_perag *pag, struct xfs_trans *tp,
xfs_extlen_t len);
int xfs_ag_get_geometry(struct xfs_perag *pag, struct xfs_ag_geometry *ageo);
#endif /* __LIBXFS_AG_H */
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