// SPDX-License-Identifier: GPL-2.0
/*
* fs/mpage.c
*
* Copyright (C) 2002, Linus Torvalds.
*
* Contains functions related to preparing and submitting BIOs which contain
* multiple pagecache pages.
*
* 15May2002 Andrew Morton
* Initial version
* 27Jun2002 axboe@suse.de
* use bio_add_page() to build bio's just the right size
*/
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/kdev_t.h>
#include <linux/gfp.h>
#include <linux/bio.h>
#include <linux/fs.h>
#include <linux/buffer_head.h>
#include <linux/blkdev.h>
#include <linux/highmem.h>
#include <linux/prefetch.h>
#include <linux/mpage.h>
#include <linux/mm_inline.h>
#include <linux/writeback.h>
#include <linux/backing-dev.h>
#include <linux/pagevec.h>
#include <linux/cleancache.h>
#include "internal.h"
/*
* I/O completion handler for multipage BIOs.
*
* The mpage code never puts partial pages into a BIO (except for end-of-file).
* If a page does not map to a contiguous run of blocks then it simply falls
* back to block_read_full_page().
*
* Why is this? If a page's completion depends on a number of different BIOs
* which can complete in any order (or at the same time) then determining the
* status of that page is hard. See end_buffer_async_read() for the details.
* There is no point in duplicating all that complexity.
*/
static void mpage_end_io(struct bio *bio)
{
struct bio_vec *bv;
struct bvec_iter_all iter_all;
bio_for_each_segment_all(bv, bio, iter_all) {
struct page *page = bv->bv_page;
page_endio(page, bio_op(bio),
blk_status_to_errno(bio->bi_status));
}
bio_put(bio);
}
static struct bio *mpage_bio_submit(int op, int op_flags, struct bio *bio)
{
bio->bi_end_io = mpage_end_io;
bio_set_op_attrs(bio, op, op_flags);
guard_bio_eod(op, bio);
submit_bio(bio);
return NULL;
}
static struct bio *
mpage_alloc(struct block_device *bdev,
sector_t first_sector, int nr_vecs,
gfp_t gfp_flags)
{
struct bio *bio;
/* Restrict the given (page cache) mask for slab allocations */
gfp_flags &= GFP_KERNEL;
bio = bio_alloc(gfp_flags, nr_vecs);
if (bio == NULL && (current->flags & PF_MEMALLOC)) {
while (!bio && (nr_vecs /= 2))
bio = bio_alloc(gfp_flags, nr_vecs);
}
if (bio) {
bio_set_dev(bio, bdev);
bio->bi_iter.bi_sector = first_sector;
}
return bio;
}
/*
* support function for mpage_readpages. The fs supplied get_block might
* return an up to date buffer. This is used to map that buffer into
* the page, which allows readpage to avoid triggering a duplicate call
* to get_block.
*
* The idea is to avoid adding buffers to pages that don't already have
* them. So when the buffer is up to date and the page size == block size,
* this marks the page up to date instead of adding new buffers.
*/
static void
map_buffer_to_page(struct page *page, struct buffer_head *bh, int page_block)
{
struct inode *inode = page->mapping->host;
struct buffer_head *page_bh, *head;
int block = 0;
if (!page_has_buffers(page)) {
/*
* don't make any buffers if there is only one buffer on
* the page and the page just needs to be set up to date
*/
if (inode->i_blkbits == PAGE_SHIFT &&
buffer_uptodate(bh)) {
SetPageUptodate(page);
return;
}
create_empty_buffers(page, i_blocksize(inode), 0);
}
head = page_buffers(page);
page_bh = head;
do {
if (block == page_block) {
page_bh->b_state = bh->b_state;
page_bh->b_bdev = bh->b_bdev;
page_bh->b_blocknr = bh->b_blocknr;
break;
}
page_bh = page_bh->b_this_page;
block++;
} while (page_bh != head);
}
struct mpage_readpage_args {
struct bio *bio;
struct page *page;
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/*
* fs/direct-io.c
*
* Copyright (C) 2002, Linus Torvalds.
*
* O_DIRECT
*
* 04Jul2002 Andrew Morton
* Initial version
* 11Sep2002 janetinc@us.ibm.com
* added readv/writev support.
* 29Oct2002 Andrew Morton
* rewrote bio_add_page() support.
* 30Oct2002 pbadari@us.ibm.com
* added support for non-aligned IO.
* 06Nov2002 pbadari@us.ibm.com
* added asynchronous IO support.
* 21Jul2003 nathans@sgi.com
* added IO completion notifier.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/bio.h>
#include <linux/wait.h>
#include <linux/err.h>
#include <linux/blkdev.h>
#include <linux/buffer_head.h>
#include <linux/rwsem.h>
#include <linux/uio.h>
#include <linux/atomic.h>
#include <linux/prefetch.h>
/*
* How many user pages to map in one call to get_user_pages(). This determines
* the size of a structure in the slab cache
*/
#define DIO_PAGES 64
/*
* Flags for dio_complete()
*/
#define DIO_COMPLETE_ASYNC 0x01 /* This is async IO */
#define DIO_COMPLETE_INVALIDATE 0x02 /* Can invalidate pages */
/*
* This code generally works in units of "dio_blocks". A dio_block is
* somewhere between the hard sector size and the filesystem block size. it
* is determined on a per-invocation basis. When talking to the filesystem
* we need to convert dio_blocks to fs_blocks by scaling the dio_block quantity
* down by dio->blkfactor. Similarly, fs-blocksize quantities are converted
* to bio_block quantities by shifting left by blkfactor.
*
* If blkfactor is zero then the user's request was aligned to the filesystem's
* blocksize.
*/
/* dio_state only used in the submission path */
struct dio_submit {
struct bio *bio; /* bio under assembly */
unsigned blkbits; /* doesn't change */
unsigned blkfactor; /* When we're using an alignment which
is finer than the filesystem's soft
blocksize, this specifies how much
finer. blkfactor=2 means 1/4-block
alignment. Does not change */
unsigned start_zero_done; /* flag: sub-blocksize zeroing has
been performed at the start of a
write */
int pages_in_io; /* approximate total IO pages */
sector_t block_in_file; /* Current offset into the underlying
file in dio_block units. */
unsigned blocks_available; /* At block_in_file. changes */
int reap_counter; /* rate limit reaping */
sector_t final_block_in_request;/* doesn't change */
int boundary; /* prev block is at a boundary */
get_block_t *get_block; /* block mapping function */
dio_submit_t *submit_io;