linux/block/bounce.c
Linus Torvalds e4bc13adfd Merge branch 'for-4.2/writeback' of git://git.kernel.dk/linux-block
Pull cgroup writeback support from Jens Axboe:
 "This is the big pull request for adding cgroup writeback support.

  This code has been in development for a long time, and it has been
  simmering in for-next for a good chunk of this cycle too.  This is one
  of those problems that has been talked about for at least half a
  decade, finally there's a solution and code to go with it.

  Also see last weeks writeup on LWN:

        http://lwn.net/Articles/648292/"

* 'for-4.2/writeback' of git://git.kernel.dk/linux-block: (85 commits)
  writeback, blkio: add documentation for cgroup writeback support
  vfs, writeback: replace FS_CGROUP_WRITEBACK with SB_I_CGROUPWB
  writeback: do foreign inode detection iff cgroup writeback is enabled
  v9fs: fix error handling in v9fs_session_init()
  bdi: fix wrong error return value in cgwb_create()
  buffer: remove unusued 'ret' variable
  writeback: disassociate inodes from dying bdi_writebacks
  writeback: implement foreign cgroup inode bdi_writeback switching
  writeback: add lockdep annotation to inode_to_wb()
  writeback: use unlocked_inode_to_wb transaction in inode_congested()
  writeback: implement unlocked_inode_to_wb transaction and use it for stat updates
  writeback: implement [locked_]inode_to_wb_and_lock_list()
  writeback: implement foreign cgroup inode detection
  writeback: make writeback_control track the inode being written back
  writeback: relocate wb[_try]_get(), wb_put(), inode_{attach|detach}_wb()
  mm: vmscan: disable memcg direct reclaim stalling if cgroup writeback support is in use
  writeback: implement memcg writeback domain based throttling
  writeback: reset wb_domain->dirty_limit[_tstmp] when memcg domain size changes
  writeback: implement memcg wb_domain
  writeback: update wb_over_bg_thresh() to use wb_domain aware operations
  ...
2015-06-25 16:00:17 -07:00

289 lines
6.4 KiB
C

/* 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>
#define POOL_SIZE 64
#define ISA_POOL_SIZE 16
static mempool_t *page_pool, *isa_page_pool;
#if defined(CONFIG_HIGHMEM) || defined(CONFIG_NEED_BOUNCE_POOL)
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);
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 = from->bi_io_vec;
struct bvec_iter iter;
bio_for_each_segment(tovec, to, 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);
}
fromvec++;
}
}
static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
{
struct bio *bio_orig = bio->bi_private;
struct bio_vec *bvec, *org_vec;
int i;
/*
* free up bounce indirect pages used
*/
bio_for_each_segment_all(bvec, bio, i) {
org_vec = bio_orig->bi_io_vec + i;
if (bvec->bv_page == org_vec->bv_page)
continue;
dec_zone_page_state(bvec->bv_page, NR_BOUNCE);
mempool_free(bvec->bv_page, pool);
}
bio_endio(bio_orig, err);
bio_put(bio);
}
static void bounce_end_io_write(struct bio *bio, int err)
{
bounce_end_io(bio, page_pool, err);
}
static void bounce_end_io_write_isa(struct bio *bio, int err)
{
bounce_end_io(bio, isa_page_pool, err);
}
static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
{
struct bio *bio_orig = bio->bi_private;
if (test_bit(BIO_UPTODATE, &bio->bi_flags))
copy_to_high_bio_irq(bio_orig, bio);
bounce_end_io(bio, pool, err);
}
static void bounce_end_io_read(struct bio *bio, int err)
{
__bounce_end_io_read(bio, page_pool, err);
}
static void bounce_end_io_read_isa(struct bio *bio, int err)
{
__bounce_end_io_read(bio, isa_page_pool, err);
}
#ifdef CONFIG_NEED_BOUNCE_POOL
static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio)
{
if (bio_data_dir(bio) != WRITE)
return 0;
if (!bdi_cap_stable_pages_required(&q->backing_dev_info))
return 0;
return test_bit(BIO_SNAP_STABLE, &bio->bi_flags);
}
#else
static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio)
{
return 0;
}
#endif /* CONFIG_NEED_BOUNCE_POOL */
static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
mempool_t *pool, int force)
{
struct bio *bio;
int rw = bio_data_dir(*bio_orig);
struct bio_vec *to, from;
struct bvec_iter iter;
unsigned i;
if (force)
goto bounce;
bio_for_each_segment(from, *bio_orig, iter)
if (page_to_pfn(from.bv_page) > queue_bounce_pfn(q))
goto bounce;
return;
bounce:
bio = bio_clone_bioset(*bio_orig, GFP_NOIO, fs_bio_set);
bio_for_each_segment_all(to, bio, i) {
struct page *page = to->bv_page;
if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force)
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)
{
int must_bounce;
mempool_t *pool;
/*
* Data-less bio, nothing to bounce
*/
if (!bio_has_data(*bio_orig))
return;
must_bounce = must_snapshot_stable_pages(q, *bio_orig);
/*
* 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 (queue_bounce_pfn(q) >= blk_max_pfn && !must_bounce)
return;
pool = page_pool;
} else {
BUG_ON(!isa_page_pool);
pool = isa_page_pool;
}
/*
* slow path
*/
__blk_queue_bounce(q, bio_orig, pool, must_bounce);
}
EXPORT_SYMBOL(blk_queue_bounce);