swh:1:snp:38ae39f9fd01a4b0ef06fab5668b65bf4c2aca03
Tip revision: b04e217704b7f879c6b91222b066983a44a7a09f authored by Linus Torvalds on 27 May 2018, 20:01:47 UTC
Linux 4.17-rc7
Linux 4.17-rc7
Tip revision: b04e217
bounce.c
// SPDX-License-Identifier: GPL-2.0
/* bounce buffer handling for block devices
*
* - Split from highmem.c
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/mm.h>
#include <linux/export.h>
#include <linux/swap.h>
#include <linux/gfp.h>
#include <linux/bio.h>
#include <linux/pagemap.h>
#include <linux/mempool.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/init.h>
#include <linux/hash.h>
#include <linux/highmem.h>
#include <linux/bootmem.h>
#include <linux/printk.h>
#include <asm/tlbflush.h>
#include <trace/events/block.h>
#include "blk.h"
#define POOL_SIZE 64
#define ISA_POOL_SIZE 16
static struct bio_set *bounce_bio_set, *bounce_bio_split;
static mempool_t *page_pool, *isa_page_pool;
#if defined(CONFIG_HIGHMEM)
static __init int init_emergency_pool(void)
{
#if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG)
if (max_pfn <= max_low_pfn)
return 0;
#endif
page_pool = mempool_create_page_pool(POOL_SIZE, 0);
BUG_ON(!page_pool);
pr_info("pool size: %d pages\n", POOL_SIZE);
bounce_bio_set = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
BUG_ON(!bounce_bio_set);
if (bioset_integrity_create(bounce_bio_set, BIO_POOL_SIZE))
BUG_ON(1);
bounce_bio_split = bioset_create(BIO_POOL_SIZE, 0, 0);
BUG_ON(!bounce_bio_split);
return 0;
}
__initcall(init_emergency_pool);
#endif
#ifdef CONFIG_HIGHMEM
/*
* highmem version, map in to vec
*/
static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
{
unsigned long flags;
unsigned char *vto;
local_irq_save(flags);
vto = kmap_atomic(to->bv_page);
memcpy(vto + to->bv_offset, vfrom, to->bv_len);
kunmap_atomic(vto);
local_irq_restore(flags);
}
#else /* CONFIG_HIGHMEM */
#define bounce_copy_vec(to, vfrom) \
memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
#endif /* CONFIG_HIGHMEM */
/*
* allocate pages in the DMA region for the ISA pool
*/
static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
{
return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
}
/*
* gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
* as the max address, so check if the pool has already been created.
*/
int init_emergency_isa_pool(void)
{
if (isa_page_pool)
return 0;
isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa,
mempool_free_pages, (void *) 0);
BUG_ON(!isa_page_pool);
pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE);
return 0;
}
/*
* Simple bounce buffer support for highmem pages. Depending on the
* queue gfp mask set, *to may or may not be a highmem page. kmap it
* always, it will do the Right Thing
*/
static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
{
unsigned char *vfrom;
struct bio_vec tovec, fromvec;
struct bvec_iter iter;
/*
* The bio of @from is created by bounce, so we can iterate
* its bvec from start to end, but the @from->bi_iter can't be
* trusted because it might be changed by splitting.
*/
struct bvec_iter from_iter = BVEC_ITER_ALL_INIT;
bio_for_each_segment(tovec, to, iter) {
fromvec = bio_iter_iovec(from, from_iter);
if (tovec.bv_page != fromvec.bv_page) {
/*
* fromvec->bv_offset and fromvec->bv_len might have
* been modified by the block layer, so use the original
* copy, bounce_copy_vec already uses tovec->bv_len
*/
vfrom = page_address(fromvec.bv_page) +
tovec.bv_offset;
bounce_copy_vec(&tovec, vfrom);
flush_dcache_page(tovec.bv_page);
}
bio_advance_iter(from, &from_iter, tovec.bv_len);
}
}
static void bounce_end_io(struct bio *bio, mempool_t *pool)
{
struct bio *bio_orig = bio->bi_private;
struct bio_vec *bvec, orig_vec;
int i;
struct bvec_iter orig_iter = bio_orig->bi_iter;
/*
* free up bounce indirect pages used
*/
bio_for_each_segment_all(bvec, bio, i) {
orig_vec = bio_iter_iovec(bio_orig, orig_iter);
if (bvec->bv_page != orig_vec.bv_page) {
dec_zone_page_state(bvec->bv_page, NR_BOUNCE);
mempool_free(bvec->bv_page, pool);
}
bio_advance_iter(bio_orig, &orig_iter, orig_vec.bv_len);
}
bio_orig->bi_status = bio->bi_status;
bio_endio(bio_orig);
bio_put(bio);
}
static void bounce_end_io_write(struct bio *bio)
{
bounce_end_io(bio, page_pool);
}
static void bounce_end_io_write_isa(struct bio *bio)
{
bounce_end_io(bio, isa_page_pool);
}
static void __bounce_end_io_read(struct bio *bio, mempool_t *pool)
{
struct bio *bio_orig = bio->bi_private;
if (!bio->bi_status)
copy_to_high_bio_irq(bio_orig, bio);
bounce_end_io(bio, pool);
}
static void bounce_end_io_read(struct bio *bio)
{
__bounce_end_io_read(bio, page_pool);
}
static void bounce_end_io_read_isa(struct bio *bio)
{
__bounce_end_io_read(bio, isa_page_pool);
}
static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
mempool_t *pool)
{
struct bio *bio;
int rw = bio_data_dir(*bio_orig);
struct bio_vec *to, from;
struct bvec_iter iter;
unsigned i = 0;
bool bounce = false;
int sectors = 0;
bool passthrough = bio_is_passthrough(*bio_orig);
bio_for_each_segment(from, *bio_orig, iter) {
if (i++ < BIO_MAX_PAGES)
sectors += from.bv_len >> 9;
if (page_to_pfn(from.bv_page) > q->limits.bounce_pfn)
bounce = true;
}
if (!bounce)
return;
if (!passthrough && sectors < bio_sectors(*bio_orig)) {
bio = bio_split(*bio_orig, sectors, GFP_NOIO, bounce_bio_split);
bio_chain(bio, *bio_orig);
generic_make_request(*bio_orig);
*bio_orig = bio;
}
bio = bio_clone_bioset(*bio_orig, GFP_NOIO, passthrough ? NULL :
bounce_bio_set);
bio_for_each_segment_all(to, bio, i) {
struct page *page = to->bv_page;
if (page_to_pfn(page) <= q->limits.bounce_pfn)
continue;
to->bv_page = mempool_alloc(pool, q->bounce_gfp);
inc_zone_page_state(to->bv_page, NR_BOUNCE);
if (rw == WRITE) {
char *vto, *vfrom;
flush_dcache_page(page);
vto = page_address(to->bv_page) + to->bv_offset;
vfrom = kmap_atomic(page) + to->bv_offset;
memcpy(vto, vfrom, to->bv_len);
kunmap_atomic(vfrom);
}
}
trace_block_bio_bounce(q, *bio_orig);
bio->bi_flags |= (1 << BIO_BOUNCED);
if (pool == page_pool) {
bio->bi_end_io = bounce_end_io_write;
if (rw == READ)
bio->bi_end_io = bounce_end_io_read;
} else {
bio->bi_end_io = bounce_end_io_write_isa;
if (rw == READ)
bio->bi_end_io = bounce_end_io_read_isa;
}
bio->bi_private = *bio_orig;
*bio_orig = bio;
}
void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
{
mempool_t *pool;
/*
* Data-less bio, nothing to bounce
*/
if (!bio_has_data(*bio_orig))
return;
/*
* for non-isa bounce case, just check if the bounce pfn is equal
* to or bigger than the highest pfn in the system -- in that case,
* don't waste time iterating over bio segments
*/
if (!(q->bounce_gfp & GFP_DMA)) {
if (q->limits.bounce_pfn >= blk_max_pfn)
return;
pool = page_pool;
} else {
BUG_ON(!isa_page_pool);
pool = isa_page_pool;
}
/*
* slow path
*/
__blk_queue_bounce(q, bio_orig, pool);
}