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linux-next/fs/logfs/dev_bdev.c
Kirill A. Shutemov 09cbfeaf1a mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.

This promise never materialized.  And unlikely will.

We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE.  And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.

Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.

Let's stop pretending that pages in page cache are special.  They are
not.

The changes are pretty straight-forward:

 - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};

 - page_cache_get() -> get_page();

 - page_cache_release() -> put_page();

This patch contains automated changes generated with coccinelle using
script below.  For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.

The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.

There are few places in the code where coccinelle didn't reach.  I'll
fix them manually in a separate patch.  Comments and documentation also
will be addressed with the separate patch.

virtual patch

@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT

@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE

@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK

@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)

@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)

@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-04 10:41:08 -07:00

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/*
* fs/logfs/dev_bdev.c - Device access methods for block devices
*
* As should be obvious for Linux kernel code, license is GPLv2
*
* Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
*/
#include "logfs.h"
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/buffer_head.h>
#include <linux/gfp.h>
#include <linux/prefetch.h>
#define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1))
static int sync_request(struct page *page, struct block_device *bdev, int rw)
{
struct bio bio;
struct bio_vec bio_vec;
bio_init(&bio);
bio.bi_max_vecs = 1;
bio.bi_io_vec = &bio_vec;
bio_vec.bv_page = page;
bio_vec.bv_len = PAGE_SIZE;
bio_vec.bv_offset = 0;
bio.bi_vcnt = 1;
bio.bi_bdev = bdev;
bio.bi_iter.bi_sector = page->index * (PAGE_SIZE >> 9);
bio.bi_iter.bi_size = PAGE_SIZE;
return submit_bio_wait(rw, &bio);
}
static int bdev_readpage(void *_sb, struct page *page)
{
struct super_block *sb = _sb;
struct block_device *bdev = logfs_super(sb)->s_bdev;
int err;
err = sync_request(page, bdev, READ);
if (err) {
ClearPageUptodate(page);
SetPageError(page);
} else {
SetPageUptodate(page);
ClearPageError(page);
}
unlock_page(page);
return err;
}
static DECLARE_WAIT_QUEUE_HEAD(wq);
static void writeseg_end_io(struct bio *bio)
{
struct bio_vec *bvec;
int i;
struct super_block *sb = bio->bi_private;
struct logfs_super *super = logfs_super(sb);
BUG_ON(bio->bi_error); /* FIXME: Retry io or write elsewhere */
bio_for_each_segment_all(bvec, bio, i) {
end_page_writeback(bvec->bv_page);
put_page(bvec->bv_page);
}
bio_put(bio);
if (atomic_dec_and_test(&super->s_pending_writes))
wake_up(&wq);
}
static int __bdev_writeseg(struct super_block *sb, u64 ofs, pgoff_t index,
size_t nr_pages)
{
struct logfs_super *super = logfs_super(sb);
struct address_space *mapping = super->s_mapping_inode->i_mapping;
struct bio *bio;
struct page *page;
unsigned int max_pages;
int i;
max_pages = min_t(size_t, nr_pages, BIO_MAX_PAGES);
bio = bio_alloc(GFP_NOFS, max_pages);
BUG_ON(!bio);
for (i = 0; i < nr_pages; i++) {
if (i >= max_pages) {
/* Block layer cannot split bios :( */
bio->bi_vcnt = i;
bio->bi_iter.bi_size = i * PAGE_SIZE;
bio->bi_bdev = super->s_bdev;
bio->bi_iter.bi_sector = ofs >> 9;
bio->bi_private = sb;
bio->bi_end_io = writeseg_end_io;
atomic_inc(&super->s_pending_writes);
submit_bio(WRITE, bio);
ofs += i * PAGE_SIZE;
index += i;
nr_pages -= i;
i = 0;
bio = bio_alloc(GFP_NOFS, max_pages);
BUG_ON(!bio);
}
page = find_lock_page(mapping, index + i);
BUG_ON(!page);
bio->bi_io_vec[i].bv_page = page;
bio->bi_io_vec[i].bv_len = PAGE_SIZE;
bio->bi_io_vec[i].bv_offset = 0;
BUG_ON(PageWriteback(page));
set_page_writeback(page);
unlock_page(page);
}
bio->bi_vcnt = nr_pages;
bio->bi_iter.bi_size = nr_pages * PAGE_SIZE;
bio->bi_bdev = super->s_bdev;
bio->bi_iter.bi_sector = ofs >> 9;
bio->bi_private = sb;
bio->bi_end_io = writeseg_end_io;
atomic_inc(&super->s_pending_writes);
submit_bio(WRITE, bio);
return 0;
}
static void bdev_writeseg(struct super_block *sb, u64 ofs, size_t len)
{
struct logfs_super *super = logfs_super(sb);
int head;
BUG_ON(super->s_flags & LOGFS_SB_FLAG_RO);
if (len == 0) {
/* This can happen when the object fit perfectly into a
* segment, the segment gets written per sync and subsequently
* closed.
*/
return;
}
head = ofs & (PAGE_SIZE - 1);
if (head) {
ofs -= head;
len += head;
}
len = PAGE_ALIGN(len);
__bdev_writeseg(sb, ofs, ofs >> PAGE_SHIFT, len >> PAGE_SHIFT);
}
static void erase_end_io(struct bio *bio)
{
struct super_block *sb = bio->bi_private;
struct logfs_super *super = logfs_super(sb);
BUG_ON(bio->bi_error); /* FIXME: Retry io or write elsewhere */
BUG_ON(bio->bi_vcnt == 0);
bio_put(bio);
if (atomic_dec_and_test(&super->s_pending_writes))
wake_up(&wq);
}
static int do_erase(struct super_block *sb, u64 ofs, pgoff_t index,
size_t nr_pages)
{
struct logfs_super *super = logfs_super(sb);
struct bio *bio;
unsigned int max_pages;
int i;
max_pages = min_t(size_t, nr_pages, BIO_MAX_PAGES);
bio = bio_alloc(GFP_NOFS, max_pages);
BUG_ON(!bio);
for (i = 0; i < nr_pages; i++) {
if (i >= max_pages) {
/* Block layer cannot split bios :( */
bio->bi_vcnt = i;
bio->bi_iter.bi_size = i * PAGE_SIZE;
bio->bi_bdev = super->s_bdev;
bio->bi_iter.bi_sector = ofs >> 9;
bio->bi_private = sb;
bio->bi_end_io = erase_end_io;
atomic_inc(&super->s_pending_writes);
submit_bio(WRITE, bio);
ofs += i * PAGE_SIZE;
index += i;
nr_pages -= i;
i = 0;
bio = bio_alloc(GFP_NOFS, max_pages);
BUG_ON(!bio);
}
bio->bi_io_vec[i].bv_page = super->s_erase_page;
bio->bi_io_vec[i].bv_len = PAGE_SIZE;
bio->bi_io_vec[i].bv_offset = 0;
}
bio->bi_vcnt = nr_pages;
bio->bi_iter.bi_size = nr_pages * PAGE_SIZE;
bio->bi_bdev = super->s_bdev;
bio->bi_iter.bi_sector = ofs >> 9;
bio->bi_private = sb;
bio->bi_end_io = erase_end_io;
atomic_inc(&super->s_pending_writes);
submit_bio(WRITE, bio);
return 0;
}
static int bdev_erase(struct super_block *sb, loff_t to, size_t len,
int ensure_write)
{
struct logfs_super *super = logfs_super(sb);
BUG_ON(to & (PAGE_SIZE - 1));
BUG_ON(len & (PAGE_SIZE - 1));
if (super->s_flags & LOGFS_SB_FLAG_RO)
return -EROFS;
if (ensure_write) {
/*
* Object store doesn't care whether erases happen or not.
* But for the journal they are required. Otherwise a scan
* can find an old commit entry and assume it is the current
* one, travelling back in time.
*/
do_erase(sb, to, to >> PAGE_SHIFT, len >> PAGE_SHIFT);
}
return 0;
}
static void bdev_sync(struct super_block *sb)
{
struct logfs_super *super = logfs_super(sb);
wait_event(wq, atomic_read(&super->s_pending_writes) == 0);
}
static struct page *bdev_find_first_sb(struct super_block *sb, u64 *ofs)
{
struct logfs_super *super = logfs_super(sb);
struct address_space *mapping = super->s_mapping_inode->i_mapping;
filler_t *filler = bdev_readpage;
*ofs = 0;
return read_cache_page(mapping, 0, filler, sb);
}
static struct page *bdev_find_last_sb(struct super_block *sb, u64 *ofs)
{
struct logfs_super *super = logfs_super(sb);
struct address_space *mapping = super->s_mapping_inode->i_mapping;
filler_t *filler = bdev_readpage;
u64 pos = (super->s_bdev->bd_inode->i_size & ~0xfffULL) - 0x1000;
pgoff_t index = pos >> PAGE_SHIFT;
*ofs = pos;
return read_cache_page(mapping, index, filler, sb);
}
static int bdev_write_sb(struct super_block *sb, struct page *page)
{
struct block_device *bdev = logfs_super(sb)->s_bdev;
/* Nothing special to do for block devices. */
return sync_request(page, bdev, WRITE);
}
static void bdev_put_device(struct logfs_super *s)
{
blkdev_put(s->s_bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
}
static int bdev_can_write_buf(struct super_block *sb, u64 ofs)
{
return 0;
}
static const struct logfs_device_ops bd_devops = {
.find_first_sb = bdev_find_first_sb,
.find_last_sb = bdev_find_last_sb,
.write_sb = bdev_write_sb,
.readpage = bdev_readpage,
.writeseg = bdev_writeseg,
.erase = bdev_erase,
.can_write_buf = bdev_can_write_buf,
.sync = bdev_sync,
.put_device = bdev_put_device,
};
int logfs_get_sb_bdev(struct logfs_super *p, struct file_system_type *type,
const char *devname)
{
struct block_device *bdev;
bdev = blkdev_get_by_path(devname, FMODE_READ|FMODE_WRITE|FMODE_EXCL,
type);
if (IS_ERR(bdev))
return PTR_ERR(bdev);
if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
int mtdnr = MINOR(bdev->bd_dev);
blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
return logfs_get_sb_mtd(p, mtdnr);
}
p->s_bdev = bdev;
p->s_mtd = NULL;
p->s_devops = &bd_devops;
return 0;
}
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