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524887347f
To deal the with the cases which inplace decompression is infeasible for some inplace I/O. Per-CPU buffers was introduced to get rid of page allocation latency and thrash for low-latency decompression algorithms such as lz4. For the big pcluster feature, introduce multipage per-CPU buffers to keep such inplace I/O pclusters temporarily as well but note that per-CPU pages are just consecutive virtually. When a new big pcluster fs is mounted, its max pclustersize will be read and per-CPU buffers can be growed if needed. Shrinking adjustable per-CPU buffers is more complex (because we don't know if such size is still be used), so currently just release them all when unloading. Link: https://lore.kernel.org/r/20210409190630.19569-1-xiang@kernel.org Acked-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
149 lines
3.1 KiB
C
149 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) Gao Xiang <xiang@kernel.org>
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*
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* For low-latency decompression algorithms (e.g. lz4), reserve consecutive
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* per-CPU virtual memory (in pages) in advance to store such inplace I/O
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* data if inplace decompression is failed (due to unmet inplace margin for
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* example).
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*/
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#include "internal.h"
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struct erofs_pcpubuf {
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raw_spinlock_t lock;
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void *ptr;
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struct page **pages;
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unsigned int nrpages;
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};
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static DEFINE_PER_CPU(struct erofs_pcpubuf, erofs_pcb);
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void *erofs_get_pcpubuf(unsigned int requiredpages)
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__acquires(pcb->lock)
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{
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struct erofs_pcpubuf *pcb = &get_cpu_var(erofs_pcb);
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raw_spin_lock(&pcb->lock);
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/* check if the per-CPU buffer is too small */
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if (requiredpages > pcb->nrpages) {
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raw_spin_unlock(&pcb->lock);
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put_cpu_var(erofs_pcb);
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/* (for sparse checker) pretend pcb->lock is still taken */
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__acquire(pcb->lock);
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return NULL;
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}
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return pcb->ptr;
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}
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void erofs_put_pcpubuf(void *ptr) __releases(pcb->lock)
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{
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struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, smp_processor_id());
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DBG_BUGON(pcb->ptr != ptr);
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raw_spin_unlock(&pcb->lock);
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put_cpu_var(erofs_pcb);
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}
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/* the next step: support per-CPU page buffers hotplug */
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int erofs_pcpubuf_growsize(unsigned int nrpages)
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{
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static DEFINE_MUTEX(pcb_resize_mutex);
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static unsigned int pcb_nrpages;
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LIST_HEAD(pagepool);
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int delta, cpu, ret, i;
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mutex_lock(&pcb_resize_mutex);
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delta = nrpages - pcb_nrpages;
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ret = 0;
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/* avoid shrinking pcpubuf, since no idea how many fses rely on */
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if (delta <= 0)
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goto out;
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for_each_possible_cpu(cpu) {
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struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, cpu);
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struct page **pages, **oldpages;
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void *ptr, *old_ptr;
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pages = kmalloc_array(nrpages, sizeof(*pages), GFP_KERNEL);
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if (!pages) {
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ret = -ENOMEM;
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break;
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}
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for (i = 0; i < nrpages; ++i) {
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pages[i] = erofs_allocpage(&pagepool, GFP_KERNEL);
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if (!pages[i]) {
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ret = -ENOMEM;
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oldpages = pages;
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goto free_pagearray;
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}
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}
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ptr = vmap(pages, nrpages, VM_MAP, PAGE_KERNEL);
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if (!ptr) {
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ret = -ENOMEM;
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oldpages = pages;
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goto free_pagearray;
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}
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raw_spin_lock(&pcb->lock);
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old_ptr = pcb->ptr;
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pcb->ptr = ptr;
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oldpages = pcb->pages;
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pcb->pages = pages;
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i = pcb->nrpages;
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pcb->nrpages = nrpages;
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raw_spin_unlock(&pcb->lock);
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if (!oldpages) {
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DBG_BUGON(old_ptr);
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continue;
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}
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if (old_ptr)
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vunmap(old_ptr);
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free_pagearray:
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while (i)
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list_add(&oldpages[--i]->lru, &pagepool);
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kfree(oldpages);
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if (ret)
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break;
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}
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pcb_nrpages = nrpages;
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put_pages_list(&pagepool);
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out:
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mutex_unlock(&pcb_resize_mutex);
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return ret;
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}
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void erofs_pcpubuf_init(void)
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{
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int cpu;
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for_each_possible_cpu(cpu) {
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struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, cpu);
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raw_spin_lock_init(&pcb->lock);
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}
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}
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void erofs_pcpubuf_exit(void)
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{
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int cpu, i;
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for_each_possible_cpu(cpu) {
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struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, cpu);
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if (pcb->ptr) {
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vunmap(pcb->ptr);
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pcb->ptr = NULL;
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}
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if (!pcb->pages)
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continue;
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for (i = 0; i < pcb->nrpages; ++i)
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if (pcb->pages[i])
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put_page(pcb->pages[i]);
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kfree(pcb->pages);
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pcb->pages = NULL;
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}
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}
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