![Theodore Ts'o](/assets/img/avatar_default.png)
If no extent conversion is required, wake up any processes waiting for the page's writeback to be complete and free the ext4_io_end structure directly in ext4_end_bio() instead of dropping it on the linked list (which requires taking a spinlock to queue and dequeue the io_end structure), and waiting for the workqueue to do this work. This removes an extra scheduling delay before process waiting for an fsync() to complete gets woken up, and it also reduces the CPU overhead for a random write workload. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
436 lines
11 KiB
C
436 lines
11 KiB
C
/*
|
|
* 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_end_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_ioend_wait(struct inode *inode)
|
|
{
|
|
wait_queue_head_t *wq = ext4_ioend_wq(inode);
|
|
|
|
wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0));
|
|
}
|
|
|
|
static void put_io_page(struct ext4_io_page *io_page)
|
|
{
|
|
if (atomic_dec_and_test(&io_page->p_count)) {
|
|
end_page_writeback(io_page->p_page);
|
|
put_page(io_page->p_page);
|
|
kmem_cache_free(io_page_cachep, io_page);
|
|
}
|
|
}
|
|
|
|
void ext4_free_io_end(ext4_io_end_t *io)
|
|
{
|
|
int i;
|
|
wait_queue_head_t *wq;
|
|
|
|
BUG_ON(!io);
|
|
if (io->page)
|
|
put_page(io->page);
|
|
for (i = 0; i < io->num_io_pages; i++)
|
|
put_io_page(io->pages[i]);
|
|
io->num_io_pages = 0;
|
|
wq = ext4_ioend_wq(io->inode);
|
|
if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count) &&
|
|
waitqueue_active(wq))
|
|
wake_up_all(wq);
|
|
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;
|
|
wait_queue_head_t *wq;
|
|
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 */
|
|
if (io->flag & EXT4_IO_END_UNWRITTEN) {
|
|
io->flag &= ~EXT4_IO_END_UNWRITTEN;
|
|
/* Wake up anyone waiting on unwritten extent conversion */
|
|
wq = ext4_ioend_wq(io->inode);
|
|
if (atomic_dec_and_test(&EXT4_I(inode)->i_aiodio_unwritten) &&
|
|
waitqueue_active(wq)) {
|
|
wake_up_all(wq);
|
|
}
|
|
}
|
|
|
|
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 = kmem_cache_zalloc(io_end_cachep, flags);
|
|
if (io) {
|
|
atomic_inc(&EXT4_I(inode)->i_ioend_count);
|
|
io->inode = 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;
|
|
int i;
|
|
sector_t bi_sector = bio->bi_sector;
|
|
|
|
BUG_ON(!io_end);
|
|
bio->bi_private = NULL;
|
|
bio->bi_end_io = NULL;
|
|
if (test_bit(BIO_UPTODATE, &bio->bi_flags))
|
|
error = 0;
|
|
bio_put(bio);
|
|
|
|
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) {
|
|
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);
|
|
|
|
}
|
|
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 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);
|
|
|
|
put_io_page(io_end->pages[i]);
|
|
}
|
|
io_end->num_io_pages = 0;
|
|
inode = io_end->inode;
|
|
|
|
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)
|
|
bi_sector >> (inode->i_blkbits - 9));
|
|
}
|
|
|
|
if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
|
|
ext4_free_io_end(io_end);
|
|
return;
|
|
}
|
|
|
|
/* 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 = NULL;
|
|
io->io_op = 0;
|
|
io->io_end = NULL;
|
|
}
|
|
|
|
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->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;
|
|
atomic_inc(&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(!PageLocked(page));
|
|
BUG_ON(PageWriteback(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;
|
|
atomic_set(&io_page->p_count, 1);
|
|
get_page(page);
|
|
set_page_writeback(page);
|
|
ClearPageError(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;
|
|
}
|
|
clear_buffer_dirty(bh);
|
|
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.
|
|
*/
|
|
put_io_page(io_page);
|
|
return ret;
|
|
}
|