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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) Gao Xiang <xiang@kernel.org>
*
* For low-latency decompression algorithms (e.g. lz4), reserve consecutive
* per-CPU virtual memory (in pages) in advance to store such inplace I/O
* data if inplace decompression is failed (due to unmet inplace margin for
* example).
*/
#include "internal.h"
struct erofs_pcpubuf {
raw_spinlock_t lock;
void *ptr;
struct page **pages;
unsigned int nrpages;
};
static DEFINE_PER_CPU(struct erofs_pcpubuf, erofs_pcb);
void *erofs_get_pcpubuf(unsigned int requiredpages)
__acquires(pcb->lock)
{
struct erofs_pcpubuf *pcb = &get_cpu_var(erofs_pcb);
raw_spin_lock(&pcb->lock);
/* check if the per-CPU buffer is too small */
if (requiredpages > pcb->nrpages) {
raw_spin_unlock(&pcb->lock);
put_cpu_var(erofs_pcb);
/* (for sparse checker) pretend pcb->lock is still taken */
__acquire(pcb->lock);
return NULL;
}
return pcb->ptr;
}
void erofs_put_pcpubuf(void *ptr) __releases(pcb->lock)
{
struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, smp_processor_id());
DBG_BUGON(pcb->ptr != ptr);
raw_spin_unlock(&pcb->lock);
put_cpu_var(erofs_pcb);
}
/* the next step: support per-CPU page buffers hotplug */
int erofs_pcpubuf_growsize(unsigned int nrpages)
{
static DEFINE_MUTEX(pcb_resize_mutex);
static unsigned int pcb_nrpages;
struct page *pagepool = NULL;
int delta, cpu, ret, i;
mutex_lock(&pcb_resize_mutex);
delta = nrpages - pcb_nrpages;
ret = 0;
/* avoid shrinking pcpubuf, since no idea how many fses rely on */
if (delta <= 0)
goto out;
for_each_possible_cpu(cpu) {
struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, cpu);
struct page **pages, **oldpages;
void *ptr, *old_ptr;
pages = kmalloc_array(nrpages, sizeof(*pages), GFP_KERNEL);
if (!pages) {
ret = -ENOMEM;
break;
}
for (i = 0; i < nrpages; ++i) {
pages[i] = erofs_allocpage(&pagepool, GFP_KERNEL);
if (!pages[i]) {
ret = -ENOMEM;
oldpages = pages;
goto free_pagearray;
}
}
ptr = vmap(pages, nrpages, VM_MAP, PAGE_KERNEL);
if (!ptr) {
ret = -ENOMEM;
oldpages = pages;
goto free_pagearray;
}
raw_spin_lock(&pcb->lock);
old_ptr = pcb->ptr;
pcb->ptr = ptr;
oldpages = pcb->pages;
pcb->pages = pages;
i = pcb->nrpages;
pcb->nrpages = nrpages;
raw_spin_unlock(&pcb->lock);
if (!oldpages) {
DBG_BUGON(old_ptr);
continue;
}
if (old_ptr)
vunmap(old_ptr);
free_pagearray:
while (i)
erofs_pagepool_add(&pagepool, oldpages[--i]);
kfree(oldpages);
if (ret)
break;
}
pcb_nrpages = nrpages;
erofs_release_pages(&pagepool);
out:
mutex_unlock(&pcb_resize_mutex);
return ret;
}
void __init erofs_pcpubuf_init(void)
{
int cpu;
for_each_possible_cpu(cpu) {
struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, cpu);
raw_spin_lock_init(&pcb->lock);
}
}
void erofs_pcpubuf_exit(void)
{
int cpu, i;
for_each_possible_cpu(cpu) {
struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, cpu);
if (pcb->ptr) {
vunmap(pcb->ptr);
pcb->ptr = NULL;
}
if (!pcb->pages)
continue;
for (i = 0; i < pcb->nrpages; ++i)
if (pcb->pages[i])
put_page(pcb->pages[i]);
kfree(pcb->pages);
pcb->pages = NULL;
}
}
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