original development tree for Linux kernel GTP module; now long in mainline.
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/*
* linux/fs/ext4/page-io.c
*
* This contains the new page_io functions for ext4
*
* Written by Theodore Ts'o, 2010.
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/time.h>
#include <linux/jbd2.h>
#include <linux/highuid.h>
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/string.h>
#include <linux/buffer_head.h>
#include <linux/writeback.h>
#include <linux/pagevec.h>
#include <linux/mpage.h>
#include <linux/namei.h>
#include <linux/uio.h>
#include <linux/bio.h>
#include <linux/workqueue.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include "ext4_jbd2.h"
#include "xattr.h"
#include "acl.h"
#include "ext4_extents.h"
static struct kmem_cache *io_page_cachep, *io_end_cachep;
int __init ext4_init_pageio(void)
{
io_page_cachep = KMEM_CACHE(ext4_io_page, SLAB_RECLAIM_ACCOUNT);
if (io_page_cachep == NULL)
return -ENOMEM;
io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
if (io_page_cachep == NULL) {
kmem_cache_destroy(io_page_cachep);
return -ENOMEM;
}
return 0;
}
void ext4_exit_pageio(void)
{
kmem_cache_destroy(io_end_cachep);
kmem_cache_destroy(io_page_cachep);
}
void ext4_free_io_end(ext4_io_end_t *io)
{
int i;
BUG_ON(!io);
if (io->page)
put_page(io->page);
for (i = 0; i < io->num_io_pages; i++) {
if (--io->pages[i]->p_count == 0) {
struct page *page = io->pages[i]->p_page;
end_page_writeback(page);
put_page(page);
kmem_cache_free(io_page_cachep, io->pages[i]);
}
}
io->num_io_pages = 0;
iput(io->inode);
kmem_cache_free(io_end_cachep, io);
}
/*
* check a range of space and convert unwritten extents to written.
*/
int ext4_end_io_nolock(ext4_io_end_t *io)
{
struct inode *inode = io->inode;
loff_t offset = io->offset;
ssize_t size = io->size;
int ret = 0;
ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
"list->prev 0x%p\n",
io, inode->i_ino, io->list.next, io->list.prev);
if (list_empty(&io->list))
return ret;
if (!(io->flag & EXT4_IO_END_UNWRITTEN))
return ret;
ret = ext4_convert_unwritten_extents(inode, offset, size);
if (ret < 0) {
printk(KERN_EMERG "%s: failed to convert unwritten "
"extents to written extents, error is %d "
"io is still on inode %lu aio dio list\n",
__func__, ret, inode->i_ino);
return ret;
}
if (io->iocb)
aio_complete(io->iocb, io->result, 0);
/* clear the DIO AIO unwritten flag */
io->flag &= ~EXT4_IO_END_UNWRITTEN;
return ret;
}
/*
* work on completed aio dio IO, to convert unwritten extents to extents
*/
static void ext4_end_io_work(struct work_struct *work)
{
ext4_io_end_t *io = container_of(work, ext4_io_end_t, work);
struct inode *inode = io->inode;
struct ext4_inode_info *ei = EXT4_I(inode);
unsigned long flags;
int ret;
mutex_lock(&inode->i_mutex);
ret = ext4_end_io_nolock(io);
if (ret < 0) {
mutex_unlock(&inode->i_mutex);
return;
}
spin_lock_irqsave(&ei->i_completed_io_lock, flags);
if (!list_empty(&io->list))
list_del_init(&io->list);
spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
mutex_unlock(&inode->i_mutex);
ext4_free_io_end(io);
}
ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
{
ext4_io_end_t *io = NULL;
io = kmem_cache_alloc(io_end_cachep, flags);
if (io) {
memset(io, 0, sizeof(*io));
io->inode = igrab(inode);
BUG_ON(!io->inode);
INIT_WORK(&io->work, ext4_end_io_work);
INIT_LIST_HEAD(&io->list);
}
return io;
}
/*
* Print an buffer I/O error compatible with the fs/buffer.c. This
* provides compatibility with dmesg scrapers that look for a specific
* buffer I/O error message. We really need a unified error reporting
* structure to userspace ala Digital Unix's uerf system, but it's
* probably not going to happen in my lifetime, due to LKML politics...
*/
static void buffer_io_error(struct buffer_head *bh)
{
char b[BDEVNAME_SIZE];
printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
bdevname(bh->b_bdev, b),
(unsigned long long)bh->b_blocknr);
}
static void ext4_end_bio(struct bio *bio, int error)
{
ext4_io_end_t *io_end = bio->bi_private;
struct workqueue_struct *wq;
struct inode *inode;
unsigned long flags;
ext4_fsblk_t err_block;
int i;
BUG_ON(!io_end);
inode = io_end->inode;
bio->bi_private = NULL;
bio->bi_end_io = NULL;
if (test_bit(BIO_UPTODATE, &bio->bi_flags))
error = 0;
err_block = bio->bi_sector >> (inode->i_blkbits - 9);
bio_put(bio);
if (!(inode->i_sb->s_flags & MS_ACTIVE)) {
pr_err("sb umounted, discard end_io request for inode %lu\n",
io_end->inode->i_ino);
ext4_free_io_end(io_end);
return;
}
if (error) {
io_end->flag |= EXT4_IO_END_ERROR;
ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
"(offset %llu size %ld starting block %llu)",
inode->i_ino,
(unsigned long long) io_end->offset,
(long) io_end->size,
(unsigned long long) err_block);
}
for (i = 0; i < io_end->num_io_pages; i++) {
struct page *page = io_end->pages[i]->p_page;
struct buffer_head *bh, *head;
int partial_write = 0;
head = page_buffers(page);
if (error)
SetPageError(page);
BUG_ON(!head);
if (head->b_size == PAGE_CACHE_SIZE)
clear_buffer_dirty(head);
else {
loff_t offset;
loff_t io_end_offset = io_end->offset + io_end->size;
offset = (sector_t) page->index << PAGE_CACHE_SHIFT;
bh = head;
do {
if ((offset >= io_end->offset) &&
(offset+bh->b_size <= io_end_offset)) {
if (error)
buffer_io_error(bh);
clear_buffer_dirty(bh);
}
if (buffer_delay(bh))
partial_write = 1;
else if (!buffer_mapped(bh))
clear_buffer_dirty(bh);
else if (buffer_dirty(bh))
partial_write = 1;
offset += bh->b_size;
bh = bh->b_this_page;
} while (bh != head);
}
if (--io_end->pages[i]->p_count == 0) {
struct page *page = io_end->pages[i]->p_page;
end_page_writeback(page);
put_page(page);
kmem_cache_free(io_page_cachep, io_end->pages[i]);
}
/*
* If this is a partial write which happened to make
* all buffers uptodate then we can optimize away a
* bogus readpage() for the next read(). Here we
* 'discover' whether the page went uptodate as a
* result of this (potentially partial) write.
*/
if (!partial_write)
SetPageUptodate(page);
}
io_end->num_io_pages = 0;
/* Add the io_end to per-inode completed io list*/
spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list);
spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);
wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq;
/* queue the work to convert unwritten extents to written */
queue_work(wq, &io_end->work);
}
void ext4_io_submit(struct ext4_io_submit *io)
{
struct bio *bio = io->io_bio;
if (bio) {
bio_get(io->io_bio);
submit_bio(io->io_op, io->io_bio);
BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
bio_put(io->io_bio);
}
io->io_bio = 0;
io->io_op = 0;
io->io_end = 0;
}
static int io_submit_init(struct ext4_io_submit *io,
struct inode *inode,
struct writeback_control *wbc,
struct buffer_head *bh)
{
ext4_io_end_t *io_end;
struct page *page = bh->b_page;
int nvecs = bio_get_nr_vecs(bh->b_bdev);
struct bio *bio;
io_end = ext4_init_io_end(inode, GFP_NOFS);
if (!io_end)
return -ENOMEM;
do {
bio = bio_alloc(GFP_NOIO, nvecs);
nvecs >>= 1;
} while (bio == NULL);
bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
bio->bi_bdev = bh->b_bdev;
bio->bi_private = io->io_end = io_end;
bio->bi_end_io = ext4_end_bio;
io_end->inode = inode;
io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
io->io_bio = bio;
io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?
WRITE_SYNC_PLUG : WRITE);
io->io_next_block = bh->b_blocknr;
return 0;
}
static int io_submit_add_bh(struct ext4_io_submit *io,
struct ext4_io_page *io_page,
struct inode *inode,
struct writeback_control *wbc,
struct buffer_head *bh)
{
ext4_io_end_t *io_end;
int ret;
if (buffer_new(bh)) {
clear_buffer_new(bh);
unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
}
if (!buffer_mapped(bh) || buffer_delay(bh)) {
if (!buffer_mapped(bh))
clear_buffer_dirty(bh);
if (io->io_bio)
ext4_io_submit(io);
return 0;
}
if (io->io_bio && bh->b_blocknr != io->io_next_block) {
submit_and_retry:
ext4_io_submit(io);
}
if (io->io_bio == NULL) {
ret = io_submit_init(io, inode, wbc, bh);
if (ret)
return ret;
}
io_end = io->io_end;
if ((io_end->num_io_pages >= MAX_IO_PAGES) &&
(io_end->pages[io_end->num_io_pages-1] != io_page))
goto submit_and_retry;
if (buffer_uninit(bh))
io->io_end->flag |= EXT4_IO_END_UNWRITTEN;
io->io_end->size += bh->b_size;
io->io_next_block++;
ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
if (ret != bh->b_size)
goto submit_and_retry;
if ((io_end->num_io_pages == 0) ||
(io_end->pages[io_end->num_io_pages-1] != io_page)) {
io_end->pages[io_end->num_io_pages++] = io_page;
io_page->p_count++;
}
return 0;
}
int ext4_bio_write_page(struct ext4_io_submit *io,
struct page *page,
int len,
struct writeback_control *wbc)
{
struct inode *inode = page->mapping->host;
unsigned block_start, block_end, blocksize;
struct ext4_io_page *io_page;
struct buffer_head *bh, *head;
int ret = 0;
blocksize = 1 << inode->i_blkbits;
BUG_ON(PageWriteback(page));
set_page_writeback(page);
ClearPageError(page);
io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS);
if (!io_page) {
set_page_dirty(page);
unlock_page(page);
return -ENOMEM;
}
io_page->p_page = page;
io_page->p_count = 0;
get_page(page);
for (bh = head = page_buffers(page), block_start = 0;
bh != head || !block_start;
block_start = block_end, bh = bh->b_this_page) {
block_end = block_start + blocksize;
if (block_start >= len) {
clear_buffer_dirty(bh);
set_buffer_uptodate(bh);
continue;
}
ret = io_submit_add_bh(io, io_page, inode, wbc, bh);
if (ret) {
/*
* We only get here on ENOMEM. Not much else
* we can do but mark the page as dirty, and
* better luck next time.
*/
set_page_dirty(page);
break;
}
}
unlock_page(page);
/*
* If the page was truncated before we could do the writeback,
* or we had a memory allocation error while trying to write
* the first buffer head, we won't have submitted any pages for
* I/O. In that case we need to make sure we've cleared the
* PageWriteback bit from the page to prevent the system from
* wedging later on.
*/
if (io_page->p_count == 0) {
put_page(page);
end_page_writeback(page);
kmem_cache_free(io_page_cachep, io_page);
}
return ret;
}