[PATCH 23/26] netfs: Remove folio_queue and rolling_buffer

David Howells
2026-03-26T10:49:33Z

Remove folio_queue and rolling_buffer as they're no longer used.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: Christoph Hellwig <hch@infradead.org>
cc: Steve French <sfrench@samba.org>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
---
Documentation/core-api/folio_queue.rst | 209 -----------------
Documentation/core-api/index.rst | 1 -
fs/netfs/iterator.c | 192 ----------------
fs/netfs/rolling_buffer.c | 297 -------------------------
include/linux/folio_queue.h | 282 -----------------------
include/linux/rolling_buffer.h | 64 ------
6 files changed, 1045 deletions(-)
delete mode 100644 Documentation/core-api/folio_queue.rst
delete mode 100644 fs/netfs/rolling_buffer.c
delete mode 100644 include/linux/folio_queue.h
delete mode 100644 include/linux/rolling_buffer.h

diff --git a/Documentation/core-api/folio_queue.rst b/Documentation/core-api/folio_queue.rst
deleted file mode 100644
index b7628896d2b6..000000000000
--- a/Documentation/core-api/folio_queue.rst
+++ /dev/null
@@ -1,209 +0,0 @@
-.. SPDX-License-Identifier: GPL-2.0+
-
-===========
-Folio Queue
-===========
-
-:Author: David Howells <dhowells@redhat.com>
-
-.. Contents:
-
- * Overview
- * Initialisation
- * Adding and removing folios
- * Querying information about a folio
- * Querying information about a folio_queue
- * Folio queue iteration
- * Folio marks
- * Lockless simultaneous production/consumption issues
-
-
-Overview
-========
-
-The folio_queue struct forms a single segment in a segmented list of folios
-that can be used to form an I/O buffer. As such, the list can be iterated over
-using the ITER_FOLIOQ iov_iter type.
-
-The publicly accessible members of the structure are::
-
- struct folio_queue {
- struct folio_queue *next;
- struct folio_queue *prev;
- ...
- };
-
-A pair of pointers are provided, ``next`` and ``prev``, that point to the
-segments on either side of the segment being accessed. Whilst this is a
-doubly-linked list, it is intentionally not a circular list; the outward
-sibling pointers in terminal segments should be NULL.
-
-Each segment in the list also stores:
-
- * an ordered sequence of folio pointers,
- * the size of each folio and
- * three 1-bit marks per folio,
-
-but these should not be accessed directly as the underlying data structure may
-change, but rather the access functions outlined below should be used.
-
-The facility can be made accessible by::
-
- #include <linux/folio_queue.h>
-
-and to use the iterator::
-
- #include <linux/uio.h>
-
-
-Initialisation
-==============
-
-A segment should be initialised by calling::
-
- void folioq_init(struct folio_queue *folioq);
-
-with a pointer to the segment to be initialised. Note that this will not
-necessarily initialise all the folio pointers, so care must be taken to check
-the number of folios added.
-
-
-Adding and removing folios
-==========================
-
-Folios can be set in the next unused slot in a segment struct by calling one
-of::
-
- unsigned int folioq_append(struct folio_queue *folioq,
- struct folio *folio);
-
- unsigned int folioq_append_mark(struct folio_queue *folioq,
- struct folio *folio);
-
-Both functions update the stored folio count, store the folio and note its
-size. The second function also sets the first mark for the folio added. Both
-functions return the number of the slot used. [!] Note that no attempt is made
-to check that the capacity wasn't overrun and the list will not be extended
-automatically.
-
-A folio can be excised by calling::
-
- void folioq_clear(struct folio_queue *folioq, unsigned int slot);
-
-This clears the slot in the array and also clears all the marks for that folio,
-but doesn't change the folio count - so future accesses of that slot must check
-if the slot is occupied.
-
-
-Querying information about a folio
-==================================
-
-Information about the folio in a particular slot may be queried by the
-following function::
-
- struct folio *folioq_folio(const struct folio_queue *folioq,
- unsigned int slot);
-
-If a folio has not yet been set in that slot, this may yield an undefined
-pointer. The size of the folio in a slot may be queried with either of::
-
- unsigned int folioq_folio_order(const struct folio_queue *folioq,
- unsigned int slot);
-
- size_t folioq_folio_size(const struct folio_queue *folioq,
- unsigned int slot);
-
-The first function returns the size as an order and the second as a number of
-bytes.
-
-
-Querying information about a folio_queue
-========================================
-
-Information may be retrieved about a particular segment with the following
-functions::
-
- unsigned int folioq_nr_slots(const struct folio_queue *folioq);
-
- unsigned int folioq_count(struct folio_queue *folioq);
-
- bool folioq_full(struct folio_queue *folioq);
-
-The first function returns the maximum capacity of a segment. It must not be
-assumed that this won't vary between segments. The second returns the number
-of folios added to a segments and the third is a shorthand to indicate if the
-segment has been filled to capacity.
-
-Not that the count and fullness are not affected by clearing folios from the
-segment. These are more about indicating how many slots in the array have been
-initialised, and it assumed that slots won't get reused, but rather the segment
-will get discarded as the queue is consumed.
-
-
-Folio marks
-===========
-
-Folios within a queue can also have marks assigned to them. These marks can be
-used to note information such as if a folio needs folio_put() calling upon it.
-There are three marks available to be set for each folio.
-
-The marks can be set by::
-
- void folioq_mark(struct folio_queue *folioq, unsigned int slot);
- void folioq_mark2(struct folio_queue *folioq, unsigned int slot);
-
-Cleared by::
-
- void folioq_unmark(struct folio_queue *folioq, unsigned int slot);
- void folioq_unmark2(struct folio_queue *folioq, unsigned int slot);
-
-And the marks can be queried by::
-
- bool folioq_is_marked(const struct folio_queue *folioq, unsigned int slot);
- bool folioq_is_marked2(const struct folio_queue *folioq, unsigned int slot);
-
-The marks can be used for any purpose and are not interpreted by this API.
-
-
-Folio queue iteration
-=====================
-
-A list of segments may be iterated over using the I/O iterator facility using
-an ``iov_iter`` iterator of ``ITER_FOLIOQ`` type. The iterator may be
-initialised with::
-
- void iov_iter_folio_queue(struct iov_iter *i, unsigned int direction,
- const struct folio_queue *folioq,
- unsigned int first_slot, unsigned int offset,
- size_t count);
-
-This may be told to start at a particular segment, slot and offset within a
-queue. The iov iterator functions will follow the next pointers when advancing
-and prev pointers when reverting when needed.
-
-
-Lockless simultaneous production/consumption issues
-===================================================
-
-If properly managed, the list can be extended by the producer at the head end
-and shortened by the consumer at the tail end simultaneously without the need
-to take locks. The ITER_FOLIOQ iterator inserts appropriate barriers to aid
-with this.
-
-Care must be taken when simultaneously producing and consuming a list. If the
-last segment is reached and the folios it refers to are entirely consumed by
-the IOV iterators, an iov_iter struct will be left pointing to the last segment
-with a slot number equal to the capacity of that segment. The iterator will
-try to continue on from this if there's another segment available when it is
-used again, but care must be taken lest the segment got removed and freed by
-the consumer before the iterator was advanced.
-
-It is recommended that the queue always contain at least one segment, even if
-that segment has never been filled or is entirely spent. This prevents the
-head and tail pointers from collapsing.
-
-
-API Function Reference
-======================
-
-.. kernel-doc:: include/linux/folio_queue.h
diff --git a/Documentation/core-api/index.rst b/Documentation/core-api/index.rst
index 13769d5c40bf..16c529a33ac4 100644
--- a/Documentation/core-api/index.rst
+++ b/Documentation/core-api/index.rst
@@ -39,7 +39,6 @@ Library functionality that is used throughout the kernel.
kref
cleanup
assoc_array
- folio_queue
xarray
maple_tree
idr
diff --git a/fs/netfs/iterator.c b/fs/netfs/iterator.c
index 442f893a0d65..7969c0b1f9a9 100644
--- a/fs/netfs/iterator.c
+++ b/fs/netfs/iterator.c
@@ -135,195 +135,3 @@ ssize_t netfs_extract_iter(struct iov_iter *orig, size_t orig_len, size_t max_se
return extracted ?: ret;
}
EXPORT_SYMBOL_GPL(netfs_extract_iter);
-
-#if 0
-/*
- * Select the span of a bvec iterator we're going to use. Limit it by both maximum
- * size and maximum number of segments. Returns the size of the span in bytes.
- */
-static size_t netfs_limit_bvec(const struct iov_iter *iter, size_t start_offset,
- size_t max_size, size_t max_segs)
-{
- const struct bio_vec *bvecs = iter->bvec;
- unsigned int nbv = iter->nr_segs, ix = 0, nsegs = 0;
- size_t len, span = 0, n = iter->count;
- size_t skip = iter->iov_offset + start_offset;
-
- if (WARN_ON(!iov_iter_is_bvec(iter)) ||
- WARN_ON(start_offset > n) ||
- n == 0)
- return 0;
-
- while (n && ix < nbv && skip) {
- len = bvecs[ix].bv_len;
- if (skip < len)
- break;
- skip -= len;
- n -= len;
- ix++;
- }
-
- while (n && ix < nbv) {
- len = min3(n, bvecs[ix].bv_len - skip, max_size);
- span += len;
- nsegs++;
- ix++;
- if (span >= max_size || nsegs >= max_segs)
- break;
- skip = 0;
- n -= len;
- }
-
- return min(span, max_size);
-}
-
-/*
- * Select the span of a kvec iterator we're going to use. Limit it by both
- * maximum size and maximum number of segments. Returns the size of the span
- * in bytes.
- */
-static size_t netfs_limit_kvec(const struct iov_iter *iter, size_t start_offset,
- size_t max_size, size_t max_segs)
-{
- const struct kvec *kvecs = iter->kvec;
- unsigned int nkv = iter->nr_segs, ix = 0, nsegs = 0;
- size_t len, span = 0, n = iter->count;
- size_t skip = iter->iov_offset + start_offset;
-
- if (WARN_ON(!iov_iter_is_kvec(iter)) ||
- WARN_ON(start_offset > n) ||
- n == 0)
- return 0;
-
- while (n && ix < nkv && skip) {
- len = kvecs[ix].iov_len;
- if (skip < len)
- break;
- skip -= len;
- n -= len;
- ix++;
- }
-
- while (n && ix < nkv) {
- len = min3(n, kvecs[ix].iov_len - skip, max_size);
- span += len;
- nsegs++;
- ix++;
- if (span >= max_size || nsegs >= max_segs)
- break;
- skip = 0;
- n -= len;
- }
-
- return min(span, max_size);
-}
-
-/*
- * Select the span of an xarray iterator we're going to use. Limit it by both
- * maximum size and maximum number of segments. It is assumed that segments
- * can be larger than a page in size, provided they're physically contiguous.
- * Returns the size of the span in bytes.
- */
-static size_t netfs_limit_xarray(const struct iov_iter *iter, size_t start_offset,
- size_t max_size, size_t max_segs)
-{
- struct folio *folio;
- unsigned int nsegs = 0;
- loff_t pos = iter->xarray_start + iter->iov_offset;
- pgoff_t index = pos / PAGE_SIZE;
- size_t span = 0, n = iter->count;
-
- XA_STATE(xas, iter->xarray, index);
-
- if (WARN_ON(!iov_iter_is_xarray(iter)) ||
- WARN_ON(start_offset > n) ||
- n == 0)
- return 0;
- max_size = min(max_size, n - start_offset);
-
- rcu_read_lock();
- xas_for_each(&xas, folio, ULONG_MAX) {
- size_t offset, flen, len;
- if (xas_retry(&xas, folio))
- continue;
- if (WARN_ON(xa_is_value(folio)))
- break;
- if (WARN_ON(folio_test_hugetlb(folio)))
- break;
-
- flen = folio_size(folio);
- offset = offset_in_folio(folio, pos);
- len = min(max_size, flen - offset);
- span += len;
- nsegs++;
- if (span >= max_size || nsegs >= max_segs)
- break;
- }
-
- rcu_read_unlock();
- return min(span, max_size);
-}
-
-/*
- * Select the span of a folio queue iterator we're going to use. Limit it by
- * both maximum size and maximum number of segments. Returns the size of the
- * span in bytes.
- */
-static size_t netfs_limit_folioq(const struct iov_iter *iter, size_t start_offset,
- size_t max_size, size_t max_segs)
-{
- const struct folio_queue *folioq = iter->folioq;
- unsigned int nsegs = 0;
- unsigned int slot = iter->folioq_slot;
- size_t span = 0, n = iter->count;
-
- if (WARN_ON(!iov_iter_is_folioq(iter)) ||
- WARN_ON(start_offset > n) ||
- n == 0)
- return 0;
- max_size = umin(max_size, n - start_offset);
-
- if (slot >= folioq_nr_slots(folioq)) {
- folioq = folioq->next;
- slot = 0;
- }
-
- start_offset += iter->iov_offset;
- do {
- size_t flen = folioq_folio_size(folioq, slot);
-
- if (start_offset < flen) {
- span += flen - start_offset;
- nsegs++;
- start_offset = 0;
- } else {
- start_offset -= flen;
- }
- if (span >= max_size || nsegs >= max_segs)
- break;
-
- slot++;
- if (slot >= folioq_nr_slots(folioq)) {
- folioq = folioq->next;
- slot = 0;
- }
- } while (folioq);
-
- return umin(span, max_size);
-}
-
-size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset,
- size_t max_size, size_t max_segs)
-{
- if (iov_iter_is_folioq(iter))
- return netfs_limit_folioq(iter, start_offset, max_size, max_segs);
- if (iov_iter_is_bvec(iter))
- return netfs_limit_bvec(iter, start_offset, max_size, max_segs);
- if (iov_iter_is_xarray(iter))
- return netfs_limit_xarray(iter, start_offset, max_size, max_segs);
- if (iov_iter_is_kvec(iter))
- return netfs_limit_kvec(iter, start_offset, max_size, max_segs);
- BUG();
-}
-EXPORT_SYMBOL(netfs_limit_iter);
-#endif
diff --git a/fs/netfs/rolling_buffer.c b/fs/netfs/rolling_buffer.c
deleted file mode 100644
index 292011c1cacb..000000000000
--- a/fs/netfs/rolling_buffer.c
+++ /dev/null
@@ -1,297 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/* Rolling buffer helpers
- *
- * Copyright (C) 2024 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- */
-
-#include <linux/bitops.h>
-#include <linux/pagemap.h>
-#include <linux/rolling_buffer.h>
-#include <linux/slab.h>
-#include "internal.h"
-
-static atomic_t debug_ids;
-
-/**
- * netfs_folioq_alloc - Allocate a folio_queue struct
- * @rreq_id: Associated debugging ID for tracing purposes
- * @gfp: Allocation constraints
- * @trace: Trace tag to indicate the purpose of the allocation
- *
- * Allocate, initialise and account the folio_queue struct and log a trace line
- * to mark the allocation.
- */
-struct folio_queue *netfs_folioq_alloc(unsigned int rreq_id, gfp_t gfp,
- unsigned int /*enum netfs_folioq_trace*/ trace)
-{
- struct folio_queue *fq;
-
- fq = kmalloc_obj(*fq, gfp);
- if (fq) {
- netfs_stat(&netfs_n_folioq);
- folioq_init(fq, rreq_id);
- fq->debug_id = atomic_inc_return(&debug_ids);
- trace_netfs_folioq(fq, trace);
- }
- return fq;
-}
-EXPORT_SYMBOL(netfs_folioq_alloc);
-
-/**
- * netfs_folioq_free - Free a folio_queue struct
- * @folioq: The object to free
- * @trace: Trace tag to indicate which free
- *
- * Free and unaccount the folio_queue struct.
- */
-void netfs_folioq_free(struct folio_queue *folioq,
- unsigned int /*enum netfs_trace_folioq*/ trace)
-{
- trace_netfs_folioq(folioq, trace);
- netfs_stat_d(&netfs_n_folioq);
- kfree(folioq);
-}
-EXPORT_SYMBOL(netfs_folioq_free);
-
-/*
- * Initialise a rolling buffer. We allocate an empty folio queue struct to so
- * that the pointers can be independently driven by the producer and the
- * consumer.
- */
-int rolling_buffer_init(struct rolling_buffer *roll, unsigned int rreq_id,
- unsigned int direction)
-{
- struct folio_queue *fq;
-
- fq = netfs_folioq_alloc(rreq_id, GFP_NOFS, netfs_trace_folioq_rollbuf_init);
- if (!fq)
- return -ENOMEM;
-
- roll->head = fq;
- roll->tail = fq;
- iov_iter_folio_queue(&roll->iter, direction, fq, 0, 0, 0);
- return 0;
-}
-
-/*
- * Add another folio_queue to a rolling buffer if there's no space left.
- */
-int rolling_buffer_make_space(struct rolling_buffer *roll)
-{
- struct folio_queue *fq, *head = roll->head;
-
- if (!folioq_full(head))
- return 0;
-
- fq = netfs_folioq_alloc(head->rreq_id, GFP_NOFS, netfs_trace_folioq_make_space);
- if (!fq)
- return -ENOMEM;
- fq->prev = head;
-
- roll->head = fq;
- if (folioq_full(head)) {
- /* Make sure we don't leave the master iterator pointing to a
- * block that might get immediately consumed.
- */
- if (roll->iter.folioq == head &&
- roll->iter.folioq_slot == folioq_nr_slots(head)) {
- roll->iter.folioq = fq;
- roll->iter.folioq_slot = 0;
- }
- }
-
- /* Make sure the initialisation is stored before the next pointer.
- *
- * [!] NOTE: After we set head->next, the consumer is at liberty to
- * immediately delete the old head.
- */
- smp_store_release(&head->next, fq);
- return 0;
-}
-
-/*
- * Decant the list of folios to read into a rolling buffer.
- */
-ssize_t rolling_buffer_load_from_ra(struct rolling_buffer *roll,
- struct readahead_control *ractl,
- struct folio_batch *put_batch)
-{
- struct folio_queue *fq;
- struct page **vec;
- int nr, ix, to;
- ssize_t size = 0;
-
- if (rolling_buffer_make_space(roll) < 0)
- return -ENOMEM;
-
- fq = roll->head;
- vec = (struct page **)fq->vec.folios;
- nr = __readahead_batch(ractl, vec + folio_batch_count(&fq->vec),
- folio_batch_space(&fq->vec));
- ix = fq->vec.nr;
- to = ix + nr;
- fq->vec.nr = to;
- for (; ix < to; ix++) {
- struct folio *folio = folioq_folio(fq, ix);
- unsigned int order = folio_order(folio);
-
- fq->orders[ix] = order;
- size += PAGE_SIZE << order;
- trace_netfs_folio(folio, netfs_folio_trace_read);
- if (!folio_batch_add(put_batch, folio))
- folio_batch_release(put_batch);
- }
- WRITE_ONCE(roll->iter.count, roll->iter.count + size);
-
- /* Store the counter after setting the slot. */
- smp_store_release(&roll->next_head_slot, to);
- return size;
-}
-
-/*
- * Decant the entire list of folios to read into a rolling buffer.
- */
-ssize_t rolling_buffer_bulk_load_from_ra(struct rolling_buffer *roll,
- struct readahead_control *ractl,
- unsigned int rreq_id)
-{
- XA_STATE(xas, &ractl->mapping->i_pages, ractl->_index);
- struct folio_queue *fq;
- struct folio *folio;
- ssize_t loaded = 0;
- int nr, slot = 0, npages = 0;
-
- /* First allocate all the folioqs we're going to need to avoid having
- * to deal with ENOMEM later.
- */
- nr = ractl->_nr_folios;
- do {
- fq = netfs_folioq_alloc(rreq_id, GFP_KERNEL,
- netfs_trace_folioq_make_space);
- if (!fq) {
- rolling_buffer_clear(roll);
- return -ENOMEM;
- }
- fq->prev = roll->head;
- if (!roll->tail)
- roll->tail = fq;
- else
- roll->head->next = fq;
- roll->head = fq;
-
- nr -= folioq_nr_slots(fq);
- } while (nr > 0);
-
- rcu_read_lock();
-
- fq = roll->tail;
- xas_for_each(&xas, folio, ractl->_index + ractl->_nr_pages - 1) {
- unsigned int order;
-
- if (xas_retry(&xas, folio))
- continue;
- VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
-
- order = folio_order(folio);
- fq->orders[slot] = order;
- fq->vec.folios[slot] = folio;
- loaded += PAGE_SIZE << order;
- npages += 1 << order;
- trace_netfs_folio(folio, netfs_folio_trace_read);
-
- slot++;
- if (slot >= folioq_nr_slots(fq)) {
- fq->vec.nr = slot;
- fq = fq->next;
- if (!fq) {
- WARN_ON_ONCE(npages < readahead_count(ractl));
- break;
- }
- slot = 0;
- }
- }
-
- rcu_read_unlock();
-
- if (fq)
- fq->vec.nr = slot;
-
- WRITE_ONCE(roll->iter.count, loaded);
- iov_iter_folio_queue(&roll->iter, ITER_DEST, roll->tail, 0, 0, loaded);
- ractl->_index += npages;
- ractl->_nr_pages -= npages;
- return loaded;
-}
-
-/*
- * Append a folio to the rolling buffer.
- */
-ssize_t rolling_buffer_append(struct rolling_buffer *roll, struct folio *folio,
- unsigned int flags)
-{
- ssize_t size = folio_size(folio);
- int slot;
-
- if (rolling_buffer_make_space(roll) < 0)
- return -ENOMEM;
-
- slot = folioq_append(roll->head, folio);
- if (flags & ROLLBUF_MARK_1)
- folioq_mark(roll->head, slot);
- if (flags & ROLLBUF_MARK_2)
- folioq_mark2(roll->head, slot);
-
- WRITE_ONCE(roll->iter.count, roll->iter.count + size);
-
- /* Store the counter after setting the slot. */
- smp_store_release(&roll->next_head_slot, slot);
- return size;
-}
-
-/*
- * Delete a spent buffer from a rolling queue and return the next in line. We
- * don't return the last buffer to keep the pointers independent, but return
- * NULL instead.
- */
-struct folio_queue *rolling_buffer_delete_spent(struct rolling_buffer *roll)
-{
- struct folio_queue *spent = roll->tail, *next = READ_ONCE(spent->next);
-
- if (!next)
- return NULL;
- next->prev = NULL;
- netfs_folioq_free(spent, netfs_trace_folioq_delete);
- roll->tail = next;
- return next;
-}
-
-/*
- * Clear out a rolling queue. Folios that have mark 1 set are put.
- */
-void rolling_buffer_clear(struct rolling_buffer *roll)
-{
- struct folio_batch fbatch;
- struct folio_queue *p;
-
- folio_batch_init(&fbatch);
-
- while ((p = roll->tail)) {
- roll->tail = p->next;
- for (int slot = 0; slot < folioq_count(p); slot++) {
- struct folio *folio = folioq_folio(p, slot);
-
- if (!folio)
- continue;
- if (folioq_is_marked(p, slot)) {
- trace_netfs_folio(folio, netfs_folio_trace_put);
- if (!folio_batch_add(&fbatch, folio))
- folio_batch_release(&fbatch);
- }
- }
-
- netfs_folioq_free(p, netfs_trace_folioq_clear);
- }
-
- folio_batch_release(&fbatch);
-}
diff --git a/include/linux/folio_queue.h b/include/linux/folio_queue.h
deleted file mode 100644
index adab609c972e..000000000000
--- a/include/linux/folio_queue.h
+++ /dev/null
@@ -1,282 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/* Queue of folios definitions
- *
- * Copyright (C) 2024 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- *
- * See:
- *
- * Documentation/core-api/folio_queue.rst
- *
- * for a description of the API.
- */
-
-#ifndef _LINUX_FOLIO_QUEUE_H
-#define _LINUX_FOLIO_QUEUE_H
-
-#include <linux/pagevec.h>
-#include <linux/mm.h>
-
-/*
- * Segment in a queue of running buffers. Each segment can hold a number of
- * folios and a portion of the queue can be referenced with the ITER_FOLIOQ
- * iterator. The possibility exists of inserting non-folio elements into the
- * queue (such as gaps).
- *
- * Explicit prev and next pointers are used instead of a list_head to make it
- * easier to add segments to tail and remove them from the head without the
- * need for a lock.
- */
-struct folio_queue {
- struct folio_batch vec; /* Folios in the queue segment */
- u8 orders[PAGEVEC_SIZE]; /* Order of each folio */
- struct folio_queue *next; /* Next queue segment or NULL */
- struct folio_queue *prev; /* Previous queue segment of NULL */
- unsigned long marks; /* 1-bit mark per folio */
- unsigned long marks2; /* Second 1-bit mark per folio */
-#if PAGEVEC_SIZE > BITS_PER_LONG
-#error marks is not big enough
-#endif
- unsigned int rreq_id;
- unsigned int debug_id;
-};
-
-/**
- * folioq_init - Initialise a folio queue segment
- * @folioq: The segment to initialise
- * @rreq_id: The request identifier to use in tracelines.
- *
- * Initialise a folio queue segment and set an identifier to be used in traces.
- *
- * Note that the folio pointers are left uninitialised.
- */
-static inline void folioq_init(struct folio_queue *folioq, unsigned int rreq_id)
-{
- folio_batch_init(&folioq->vec);
- folioq->next = NULL;
- folioq->prev = NULL;
- folioq->marks = 0;
- folioq->marks2 = 0;
- folioq->rreq_id = rreq_id;
- folioq->debug_id = 0;
-}
-
-/**
- * folioq_nr_slots: Query the capacity of a folio queue segment
- * @folioq: The segment to query
- *
- * Query the number of folios that a particular folio queue segment might hold.
- * [!] NOTE: This must not be assumed to be the same for every segment!
- */
-static inline unsigned int folioq_nr_slots(const struct folio_queue *folioq)
-{
- return PAGEVEC_SIZE;
-}
-
-/**
- * folioq_count: Query the occupancy of a folio queue segment
- * @folioq: The segment to query
- *
- * Query the number of folios that have been added to a folio queue segment.
- * Note that this is not decreased as folios are removed from a segment.
- */
-static inline unsigned int folioq_count(struct folio_queue *folioq)
-{
- return folio_batch_count(&folioq->vec);
-}
-
-/**
- * folioq_full: Query if a folio queue segment is full
- * @folioq: The segment to query
- *
- * Query if a folio queue segment is fully occupied. Note that this does not
- * change if folios are removed from a segment.
- */
-static inline bool folioq_full(struct folio_queue *folioq)
-{
- //return !folio_batch_space(&folioq->vec);
- return folioq_count(folioq) >= folioq_nr_slots(folioq);
-}
-
-/**
- * folioq_is_marked: Check first folio mark in a folio queue segment
- * @folioq: The segment to query
- * @slot: The slot number of the folio to query
- *
- * Determine if the first mark is set for the folio in the specified slot in a
- * folio queue segment.
- */
-static inline bool folioq_is_marked(const struct folio_queue *folioq, unsigned int slot)
-{
- return test_bit(slot, &folioq->marks);
-}
-
-/**
- * folioq_mark: Set the first mark on a folio in a folio queue segment
- * @folioq: The segment to modify
- * @slot: The slot number of the folio to modify
- *
- * Set the first mark for the folio in the specified slot in a folio queue
- * segment.
- */
-static inline void folioq_mark(struct folio_queue *folioq, unsigned int slot)
-{
- set_bit(slot, &folioq->marks);
-}
-
-/**
- * folioq_unmark: Clear the first mark on a folio in a folio queue segment
- * @folioq: The segment to modify
- * @slot: The slot number of the folio to modify
- *
- * Clear the first mark for the folio in the specified slot in a folio queue
- * segment.
- */
-static inline void folioq_unmark(struct folio_queue *folioq, unsigned int slot)
-{
- clear_bit(slot, &folioq->marks);
-}
-
-/**
- * folioq_is_marked2: Check second folio mark in a folio queue segment
- * @folioq: The segment to query
- * @slot: The slot number of the folio to query
- *
- * Determine if the second mark is set for the folio in the specified slot in a
- * folio queue segment.
- */
-static inline bool folioq_is_marked2(const struct folio_queue *folioq, unsigned int slot)
-{
- return test_bit(slot, &folioq->marks2);
-}
-
-/**
- * folioq_mark2: Set the second mark on a folio in a folio queue segment
- * @folioq: The segment to modify
- * @slot: The slot number of the folio to modify
- *
- * Set the second mark for the folio in the specified slot in a folio queue
- * segment.
- */
-static inline void folioq_mark2(struct folio_queue *folioq, unsigned int slot)
-{
- set_bit(slot, &folioq->marks2);
-}
-
-/**
- * folioq_unmark2: Clear the second mark on a folio in a folio queue segment
- * @folioq: The segment to modify
- * @slot: The slot number of the folio to modify
- *
- * Clear the second mark for the folio in the specified slot in a folio queue
- * segment.
- */
-static inline void folioq_unmark2(struct folio_queue *folioq, unsigned int slot)
-{
- clear_bit(slot, &folioq->marks2);
-}
-
-/**
- * folioq_append: Add a folio to a folio queue segment
- * @folioq: The segment to add to
- * @folio: The folio to add
- *
- * Add a folio to the tail of the sequence in a folio queue segment, increasing
- * the occupancy count and returning the slot number for the folio just added.
- * The folio size is extracted and stored in the queue and the marks are left
- * unmodified.
- *
- * Note that it's left up to the caller to check that the segment capacity will
- * not be exceeded and to extend the queue.
- */
-static inline unsigned int folioq_append(struct folio_queue *folioq, struct folio *folio)
-{
- unsigned int slot = folioq->vec.nr++;
-
- folioq->vec.folios[slot] = folio;
- folioq->orders[slot] = folio_order(folio);
- return slot;
-}
-
-/**
- * folioq_append_mark: Add a folio to a folio queue segment
- * @folioq: The segment to add to
- * @folio: The folio to add
- *
- * Add a folio to the tail of the sequence in a folio queue segment, increasing
- * the occupancy count and returning the slot number for the folio just added.
- * The folio size is extracted and stored in the queue, the first mark is set
- * and and the second and third marks are left unmodified.
- *
- * Note that it's left up to the caller to check that the segment capacity will
- * not be exceeded and to extend the queue.
- */
-static inline unsigned int folioq_append_mark(struct folio_queue *folioq, struct folio *folio)
-{
- unsigned int slot = folioq->vec.nr++;
-
- folioq->vec.folios[slot] = folio;
- folioq->orders[slot] = folio_order(folio);
- folioq_mark(folioq, slot);
- return slot;
-}
-
-/**
- * folioq_folio: Get a folio from a folio queue segment
- * @folioq: The segment to access
- * @slot: The folio slot to access
- *
- * Retrieve the folio in the specified slot from a folio queue segment. Note
- * that no bounds check is made and if the slot hasn't been added into yet, the
- * pointer will be undefined. If the slot has been cleared, NULL will be
- * returned.
- */
-static inline struct folio *folioq_folio(const struct folio_queue *folioq, unsigned int slot)
-{
- return folioq->vec.folios[slot];
-}
-
-/**
- * folioq_folio_order: Get the order of a folio from a folio queue segment
- * @folioq: The segment to access
- * @slot: The folio slot to access
- *
- * Retrieve the order of the folio in the specified slot from a folio queue
- * segment. Note that no bounds check is made and if the slot hasn't been
- * added into yet, the order returned will be 0.
- */
-static inline unsigned int folioq_folio_order(const struct folio_queue *folioq, unsigned int slot)
-{
- return folioq->orders[slot];
-}
-
-/**
- * folioq_folio_size: Get the size of a folio from a folio queue segment
- * @folioq: The segment to access
- * @slot: The folio slot to access
- *
- * Retrieve the size of the folio in the specified slot from a folio queue
- * segment. Note that no bounds check is made and if the slot hasn't been
- * added into yet, the size returned will be PAGE_SIZE.
- */
-static inline size_t folioq_folio_size(const struct folio_queue *folioq, unsigned int slot)
-{
- return PAGE_SIZE << folioq_folio_order(folioq, slot);
-}
-
-/**
- * folioq_clear: Clear a folio from a folio queue segment
- * @folioq: The segment to clear
- * @slot: The folio slot to clear
- *
- * Clear a folio from a sequence in a folio queue segment and clear its marks.
- * The occupancy count is left unchanged.
- */
-static inline void folioq_clear(struct folio_queue *folioq, unsigned int slot)
-{
- folioq->vec.folios[slot] = NULL;
- folioq_unmark(folioq, slot);
- folioq_unmark2(folioq, slot);
-}
-
-#endif /* _LINUX_FOLIO_QUEUE_H */
diff --git a/include/linux/rolling_buffer.h b/include/linux/rolling_buffer.h
deleted file mode 100644
index b35ef43f325f..000000000000
--- a/include/linux/rolling_buffer.h
+++ /dev/null
@@ -1,64 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/* Rolling buffer of folios
- *
- * Copyright (C) 2024 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- */
-
-#ifndef _ROLLING_BUFFER_H
-#define _ROLLING_BUFFER_H
-
-#include <linux/folio_queue.h>
-#include <linux/uio.h>
-
-/*
- * Rolling buffer. Whilst the buffer is live and in use, folios and folio
- * queue segments can be added to one end by one thread and removed from the
- * other end by another thread. The buffer isn't allowed to be empty; it must
- * always have at least one folio_queue in it so that neither side has to
- * modify both queue pointers.
- *
- * The iterator in the buffer is extended as buffers are inserted. It can be
- * snapshotted to use a segment of the buffer.
- */
-struct rolling_buffer {
- struct folio_queue *head; /* Producer's insertion point */
- struct folio_queue *tail; /* Consumer's removal point */
- struct iov_iter iter; /* Iterator tracking what's left in the buffer */
- u8 next_head_slot; /* Next slot in ->head */
- u8 first_tail_slot; /* First slot in ->tail */
-};
-
-/*
- * Snapshot of a rolling buffer.
- */
-struct rolling_buffer_snapshot {
- struct folio_queue *curr_folioq; /* Queue segment in which current folio resides */
- unsigned char curr_slot; /* Folio currently being read */
- unsigned char curr_order; /* Order of folio */
-};
-
-/* Marks to store per-folio in the internal folio_queue structs. */
-#define ROLLBUF_MARK_1 BIT(0)
-#define ROLLBUF_MARK_2 BIT(1)
-
-int rolling_buffer_init(struct rolling_buffer *roll, unsigned int rreq_id,
- unsigned int direction);
-int rolling_buffer_make_space(struct rolling_buffer *roll);
-ssize_t rolling_buffer_load_from_ra(struct rolling_buffer *roll,
- struct readahead_control *ractl,
- struct folio_batch *put_batch);
-ssize_t rolling_buffer_bulk_load_from_ra(struct rolling_buffer *roll,
- struct readahead_control *ractl,
- unsigned int rreq_id);
-ssize_t rolling_buffer_append(struct rolling_buffer *roll, struct folio *folio,
- unsigned int flags);
-struct folio_queue *rolling_buffer_delete_spent(struct rolling_buffer *roll);
-void rolling_buffer_clear(struct rolling_buffer *roll);
-
-static inline void rolling_buffer_advance(struct rolling_buffer *roll, size_t amount)
-{
- iov_iter_advance(&roll->iter, amount);
-}
-
-#endif /* _ROLLING_BUFFER_H */