325 lines
9.8 KiB
C
325 lines
9.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/* Queue of folios definitions
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*
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* Copyright (C) 2024 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* See:
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*
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* Documentation/core-api/folio_queue.rst
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*
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* for a description of the API.
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*/
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#ifndef _LINUX_FOLIO_QUEUE_H
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#define _LINUX_FOLIO_QUEUE_H
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#include <linux/pagevec.h>
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/*
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* Segment in a queue of running buffers. Each segment can hold a number of
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* folios and a portion of the queue can be referenced with the ITER_FOLIOQ
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* iterator. The possibility exists of inserting non-folio elements into the
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* queue (such as gaps).
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*
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* Explicit prev and next pointers are used instead of a list_head to make it
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* easier to add segments to tail and remove them from the head without the
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* need for a lock.
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*/
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struct folio_queue {
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struct folio_batch vec; /* Folios in the queue segment */
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u8 orders[PAGEVEC_SIZE]; /* Order of each folio */
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struct folio_queue *next; /* Next queue segment or NULL */
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struct folio_queue *prev; /* Previous queue segment of NULL */
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unsigned long marks; /* 1-bit mark per folio */
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unsigned long marks2; /* Second 1-bit mark per folio */
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unsigned long marks3; /* Third 1-bit mark per folio */
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#if PAGEVEC_SIZE > BITS_PER_LONG
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#error marks is not big enough
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#endif
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};
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/**
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* folioq_init - Initialise a folio queue segment
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* @folioq: The segment to initialise
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*
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* Initialise a folio queue segment. Note that the folio pointers are
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* left uninitialised.
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*/
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static inline void folioq_init(struct folio_queue *folioq)
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{
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folio_batch_init(&folioq->vec);
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folioq->next = NULL;
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folioq->prev = NULL;
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folioq->marks = 0;
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folioq->marks2 = 0;
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folioq->marks3 = 0;
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}
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/**
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* folioq_nr_slots: Query the capacity of a folio queue segment
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* @folioq: The segment to query
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*
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* Query the number of folios that a particular folio queue segment might hold.
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* [!] NOTE: This must not be assumed to be the same for every segment!
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*/
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static inline unsigned int folioq_nr_slots(const struct folio_queue *folioq)
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{
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return PAGEVEC_SIZE;
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}
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/**
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* folioq_count: Query the occupancy of a folio queue segment
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* @folioq: The segment to query
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*
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* Query the number of folios that have been added to a folio queue segment.
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* Note that this is not decreased as folios are removed from a segment.
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*/
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static inline unsigned int folioq_count(struct folio_queue *folioq)
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{
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return folio_batch_count(&folioq->vec);
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}
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/**
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* folioq_full: Query if a folio queue segment is full
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* @folioq: The segment to query
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*
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* Query if a folio queue segment is fully occupied. Note that this does not
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* change if folios are removed from a segment.
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*/
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static inline bool folioq_full(struct folio_queue *folioq)
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{
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//return !folio_batch_space(&folioq->vec);
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return folioq_count(folioq) >= folioq_nr_slots(folioq);
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}
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/**
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* folioq_is_marked: Check first folio mark in a folio queue segment
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* @folioq: The segment to query
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* @slot: The slot number of the folio to query
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*
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* Determine if the first mark is set for the folio in the specified slot in a
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* folio queue segment.
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*/
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static inline bool folioq_is_marked(const struct folio_queue *folioq, unsigned int slot)
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{
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return test_bit(slot, &folioq->marks);
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}
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/**
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* folioq_mark: Set the first mark on a folio in a folio queue segment
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* @folioq: The segment to modify
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* @slot: The slot number of the folio to modify
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*
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* Set the first mark for the folio in the specified slot in a folio queue
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* segment.
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*/
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static inline void folioq_mark(struct folio_queue *folioq, unsigned int slot)
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{
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set_bit(slot, &folioq->marks);
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}
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/**
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* folioq_unmark: Clear the first mark on a folio in a folio queue segment
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* @folioq: The segment to modify
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* @slot: The slot number of the folio to modify
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*
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* Clear the first mark for the folio in the specified slot in a folio queue
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* segment.
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*/
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static inline void folioq_unmark(struct folio_queue *folioq, unsigned int slot)
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{
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clear_bit(slot, &folioq->marks);
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}
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/**
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* folioq_is_marked2: Check second folio mark in a folio queue segment
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* @folioq: The segment to query
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* @slot: The slot number of the folio to query
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*
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* Determine if the second mark is set for the folio in the specified slot in a
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* folio queue segment.
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*/
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static inline bool folioq_is_marked2(const struct folio_queue *folioq, unsigned int slot)
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{
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return test_bit(slot, &folioq->marks2);
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}
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/**
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* folioq_mark2: Set the second mark on a folio in a folio queue segment
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* @folioq: The segment to modify
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* @slot: The slot number of the folio to modify
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*
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* Set the second mark for the folio in the specified slot in a folio queue
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* segment.
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*/
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static inline void folioq_mark2(struct folio_queue *folioq, unsigned int slot)
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{
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set_bit(slot, &folioq->marks2);
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}
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/**
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* folioq_unmark2: Clear the second mark on a folio in a folio queue segment
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* @folioq: The segment to modify
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* @slot: The slot number of the folio to modify
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*
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* Clear the second mark for the folio in the specified slot in a folio queue
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* segment.
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*/
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static inline void folioq_unmark2(struct folio_queue *folioq, unsigned int slot)
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{
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clear_bit(slot, &folioq->marks2);
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}
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/**
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* folioq_is_marked3: Check third folio mark in a folio queue segment
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* @folioq: The segment to query
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* @slot: The slot number of the folio to query
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*
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* Determine if the third mark is set for the folio in the specified slot in a
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* folio queue segment.
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*/
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static inline bool folioq_is_marked3(const struct folio_queue *folioq, unsigned int slot)
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{
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return test_bit(slot, &folioq->marks3);
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}
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/**
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* folioq_mark3: Set the third mark on a folio in a folio queue segment
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* @folioq: The segment to modify
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* @slot: The slot number of the folio to modify
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*
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* Set the third mark for the folio in the specified slot in a folio queue
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* segment.
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*/
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static inline void folioq_mark3(struct folio_queue *folioq, unsigned int slot)
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{
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set_bit(slot, &folioq->marks3);
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}
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/**
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* folioq_unmark3: Clear the third mark on a folio in a folio queue segment
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* @folioq: The segment to modify
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* @slot: The slot number of the folio to modify
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*
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* Clear the third mark for the folio in the specified slot in a folio queue
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* segment.
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*/
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static inline void folioq_unmark3(struct folio_queue *folioq, unsigned int slot)
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{
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clear_bit(slot, &folioq->marks3);
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}
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static inline unsigned int __folio_order(struct folio *folio)
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{
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if (!folio_test_large(folio))
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return 0;
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return folio->_flags_1 & 0xff;
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}
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/**
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* folioq_append: Add a folio to a folio queue segment
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* @folioq: The segment to add to
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* @folio: The folio to add
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*
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* Add a folio to the tail of the sequence in a folio queue segment, increasing
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* the occupancy count and returning the slot number for the folio just added.
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* The folio size is extracted and stored in the queue and the marks are left
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* unmodified.
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*
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* Note that it's left up to the caller to check that the segment capacity will
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* not be exceeded and to extend the queue.
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*/
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static inline unsigned int folioq_append(struct folio_queue *folioq, struct folio *folio)
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{
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unsigned int slot = folioq->vec.nr++;
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folioq->vec.folios[slot] = folio;
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folioq->orders[slot] = __folio_order(folio);
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return slot;
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}
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/**
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* folioq_append_mark: Add a folio to a folio queue segment
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* @folioq: The segment to add to
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* @folio: The folio to add
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*
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* Add a folio to the tail of the sequence in a folio queue segment, increasing
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* the occupancy count and returning the slot number for the folio just added.
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* The folio size is extracted and stored in the queue, the first mark is set
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* and and the second and third marks are left unmodified.
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*
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* Note that it's left up to the caller to check that the segment capacity will
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* not be exceeded and to extend the queue.
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*/
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static inline unsigned int folioq_append_mark(struct folio_queue *folioq, struct folio *folio)
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{
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unsigned int slot = folioq->vec.nr++;
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folioq->vec.folios[slot] = folio;
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folioq->orders[slot] = __folio_order(folio);
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folioq_mark(folioq, slot);
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return slot;
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}
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/**
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* folioq_folio: Get a folio from a folio queue segment
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* @folioq: The segment to access
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* @slot: The folio slot to access
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*
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* Retrieve the folio in the specified slot from a folio queue segment. Note
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* that no bounds check is made and if the slot hasn't been added into yet, the
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* pointer will be undefined. If the slot has been cleared, NULL will be
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* returned.
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*/
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static inline struct folio *folioq_folio(const struct folio_queue *folioq, unsigned int slot)
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{
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return folioq->vec.folios[slot];
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}
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/**
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* folioq_folio_order: Get the order of a folio from a folio queue segment
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* @folioq: The segment to access
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* @slot: The folio slot to access
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*
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* Retrieve the order of the folio in the specified slot from a folio queue
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* segment. Note that no bounds check is made and if the slot hasn't been
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* added into yet, the order returned will be 0.
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*/
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static inline unsigned int folioq_folio_order(const struct folio_queue *folioq, unsigned int slot)
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{
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return folioq->orders[slot];
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}
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/**
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* folioq_folio_size: Get the size of a folio from a folio queue segment
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* @folioq: The segment to access
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* @slot: The folio slot to access
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*
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* Retrieve the size of the folio in the specified slot from a folio queue
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* segment. Note that no bounds check is made and if the slot hasn't been
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* added into yet, the size returned will be PAGE_SIZE.
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*/
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static inline size_t folioq_folio_size(const struct folio_queue *folioq, unsigned int slot)
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{
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return PAGE_SIZE << folioq_folio_order(folioq, slot);
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}
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/**
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* folioq_clear: Clear a folio from a folio queue segment
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* @folioq: The segment to clear
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* @slot: The folio slot to clear
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*
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* Clear a folio from a sequence in a folio queue segment and clear its marks.
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* The occupancy count is left unchanged.
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*/
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static inline void folioq_clear(struct folio_queue *folioq, unsigned int slot)
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{
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folioq->vec.folios[slot] = NULL;
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folioq_unmark(folioq, slot);
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folioq_unmark2(folioq, slot);
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folioq_unmark3(folioq, slot);
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}
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#endif /* _LINUX_FOLIO_QUEUE_H */
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