c47260d4ea
A long time ago, I added to XFS the ability to use deferred reference
count operations as part of a transaction chain. This enabled us to
avoid blowing out the transaction reservation when the blocks in a
physical extent all had different reference counts because we could ask
the deferred operation manager for a continuation, which would get us a
clean transaction.
The refcount code asks for a continuation when the number of refcount
record updates reaches the point where we think that the transaction has
logged enough full btree blocks due to refcount (and free space) btree
shape changes and refcount record updates that we're in danger of
overflowing the transaction.
We did not previously count the EFIs logged to the refcount update
transaction because the clamps on the length of a bunmap operation were
sufficient to avoid overflowing the transaction reservation even in the
worst case situation where every other block of the unmapped extent is
shared.
Unfortunately, the restrictions on bunmap length avoid failure in the
worst case by imposing a maximum unmap length of ~3000 blocks, even for
non-pathological cases. This seriously limits performance when freeing
large extents.
Therefore, track EFIs with the same counter as refcount record updates,
and use that information as input into when we should ask for a
continuation. This enables the next patch to drop the clumsy bunmap
limitation.
Depends: 27dada070d59 ("xfs: change the order in which child and parent defer ops ar finished")
Depends: 74f4d6a1e065 ("xfs: only relog deferred intent items if free space in the log gets low")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
100 lines
3.5 KiB
C
100 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (C) 2016 Oracle. All Rights Reserved.
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* Author: Darrick J. Wong <darrick.wong@oracle.com>
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*/
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#ifndef __XFS_REFCOUNT_H__
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#define __XFS_REFCOUNT_H__
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struct xfs_trans;
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struct xfs_mount;
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struct xfs_perag;
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struct xfs_btree_cur;
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struct xfs_bmbt_irec;
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struct xfs_refcount_irec;
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extern int xfs_refcount_lookup_le(struct xfs_btree_cur *cur,
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xfs_agblock_t bno, int *stat);
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extern int xfs_refcount_lookup_ge(struct xfs_btree_cur *cur,
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xfs_agblock_t bno, int *stat);
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extern int xfs_refcount_lookup_eq(struct xfs_btree_cur *cur,
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xfs_agblock_t bno, int *stat);
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extern int xfs_refcount_get_rec(struct xfs_btree_cur *cur,
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struct xfs_refcount_irec *irec, int *stat);
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enum xfs_refcount_intent_type {
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XFS_REFCOUNT_INCREASE = 1,
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XFS_REFCOUNT_DECREASE,
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XFS_REFCOUNT_ALLOC_COW,
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XFS_REFCOUNT_FREE_COW,
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};
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struct xfs_refcount_intent {
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struct list_head ri_list;
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enum xfs_refcount_intent_type ri_type;
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xfs_extlen_t ri_blockcount;
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xfs_fsblock_t ri_startblock;
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};
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void xfs_refcount_increase_extent(struct xfs_trans *tp,
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struct xfs_bmbt_irec *irec);
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void xfs_refcount_decrease_extent(struct xfs_trans *tp,
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struct xfs_bmbt_irec *irec);
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extern void xfs_refcount_finish_one_cleanup(struct xfs_trans *tp,
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struct xfs_btree_cur *rcur, int error);
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extern int xfs_refcount_finish_one(struct xfs_trans *tp,
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enum xfs_refcount_intent_type type, xfs_fsblock_t startblock,
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xfs_extlen_t blockcount, xfs_fsblock_t *new_fsb,
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xfs_extlen_t *new_len, struct xfs_btree_cur **pcur);
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extern int xfs_refcount_find_shared(struct xfs_btree_cur *cur,
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xfs_agblock_t agbno, xfs_extlen_t aglen, xfs_agblock_t *fbno,
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xfs_extlen_t *flen, bool find_end_of_shared);
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void xfs_refcount_alloc_cow_extent(struct xfs_trans *tp, xfs_fsblock_t fsb,
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xfs_extlen_t len);
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void xfs_refcount_free_cow_extent(struct xfs_trans *tp, xfs_fsblock_t fsb,
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xfs_extlen_t len);
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extern int xfs_refcount_recover_cow_leftovers(struct xfs_mount *mp,
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struct xfs_perag *pag);
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/*
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* While we're adjusting the refcounts records of an extent, we have
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* to keep an eye on the number of extents we're dirtying -- run too
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* many in a single transaction and we'll exceed the transaction's
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* reservation and crash the fs. Each record adds 12 bytes to the
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* log (plus any key updates) so we'll conservatively assume 32 bytes
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* per record. We must also leave space for btree splits on both ends
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* of the range and space for the CUD and a new CUI.
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*
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* Each EFI that we attach to the transaction is assumed to consume ~32 bytes.
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* This is a low estimate for an EFI tracking a single extent (16 bytes for the
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* EFI header, 16 for the extent, and 12 for the xlog op header), but the
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* estimate is acceptable if there's more than one extent being freed.
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* In the worst case of freeing every other block during a refcount decrease
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* operation, we amortize the space used for one EFI log item across 16
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* extents.
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*/
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#define XFS_REFCOUNT_ITEM_OVERHEAD 32
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static inline xfs_fileoff_t xfs_refcount_max_unmap(int log_res)
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{
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return (log_res * 3 / 4) / XFS_REFCOUNT_ITEM_OVERHEAD;
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}
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extern int xfs_refcount_has_record(struct xfs_btree_cur *cur,
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xfs_agblock_t bno, xfs_extlen_t len, bool *exists);
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union xfs_btree_rec;
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extern void xfs_refcount_btrec_to_irec(const union xfs_btree_rec *rec,
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struct xfs_refcount_irec *irec);
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extern int xfs_refcount_insert(struct xfs_btree_cur *cur,
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struct xfs_refcount_irec *irec, int *stat);
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extern struct kmem_cache *xfs_refcount_intent_cache;
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int __init xfs_refcount_intent_init_cache(void);
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void xfs_refcount_intent_destroy_cache(void);
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#endif /* __XFS_REFCOUNT_H__ */
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