Commit bd2d0210 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: use bio layer instead of buffer layer in mpage_da_submit_io



Call the block I/O layer directly instad of going through the buffer
layer.  This should give us much better performance and scalability,
as well as lowering our CPU utilization when doing buffered writeback.
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 1de3e3df
......@@ -4,7 +4,7 @@
obj-$(CONFIG_EXT4_FS) += ext4.o
ext4-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o \
ext4-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o page-io.o \
ioctl.o namei.o super.o symlink.o hash.o resize.o extents.o \
ext4_jbd2.o migrate.o mballoc.o block_validity.o move_extent.o
......
......@@ -168,7 +168,20 @@ struct mpage_da_data {
int pages_written;
int retval;
};
#define EXT4_IO_UNWRITTEN 0x1
/*
* Flags for ext4_io_end->flags
*/
#define EXT4_IO_END_UNWRITTEN 0x0001
#define EXT4_IO_END_ERROR 0x0002
struct ext4_io_page {
struct page *p_page;
int p_count;
};
#define MAX_IO_PAGES 128
typedef struct ext4_io_end {
struct list_head list; /* per-file finished IO list */
struct inode *inode; /* file being written to */
......@@ -179,8 +192,18 @@ typedef struct ext4_io_end {
struct work_struct work; /* data work queue */
struct kiocb *iocb; /* iocb struct for AIO */
int result; /* error value for AIO */
int num_io_pages;
struct ext4_io_page *pages[MAX_IO_PAGES];
} ext4_io_end_t;
struct ext4_io_submit {
int io_op;
struct bio *io_bio;
ext4_io_end_t *io_end;
struct ext4_io_page *io_page;
sector_t io_next_block;
};
/*
* Special inodes numbers
*/
......@@ -2044,6 +2067,17 @@ extern int ext4_move_extents(struct file *o_filp, struct file *d_filp,
__u64 start_orig, __u64 start_donor,
__u64 len, __u64 *moved_len);
/* page-io.c */
extern int __init init_ext4_pageio(void);
extern void exit_ext4_pageio(void);
extern void ext4_free_io_end(ext4_io_end_t *io);
extern ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags);
extern int ext4_end_io_nolock(ext4_io_end_t *io);
extern void ext4_io_submit(struct ext4_io_submit *io);
extern int ext4_bio_write_page(struct ext4_io_submit *io,
struct page *page,
int len,
struct writeback_control *wbc);
/* BH_Uninit flag: blocks are allocated but uninitialized on disk */
enum ext4_state_bits {
......
......@@ -3202,7 +3202,7 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
* completed
*/
if (io)
io->flag = EXT4_IO_UNWRITTEN;
io->flag = EXT4_IO_END_UNWRITTEN;
else
ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
if (ext4_should_dioread_nolock(inode))
......@@ -3494,7 +3494,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
*/
if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
if (io)
io->flag = EXT4_IO_UNWRITTEN;
io->flag = EXT4_IO_END_UNWRITTEN;
else
ext4_set_inode_state(inode,
EXT4_STATE_DIO_UNWRITTEN);
......
......@@ -2016,8 +2016,10 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
struct buffer_head *bh, *page_bufs = NULL;
int journal_data = ext4_should_journal_data(inode);
sector_t pblock = 0, cur_logical = 0;
struct ext4_io_submit io_submit;
BUG_ON(mpd->next_page <= mpd->first_page);
memset(&io_submit, 0, sizeof(io_submit));
/*
* We need to start from the first_page to the next_page - 1
* to make sure we also write the mapped dirty buffer_heads.
......@@ -2109,16 +2111,16 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
/* mark the buffer_heads as dirty & uptodate */
block_commit_write(page, 0, len);
if (journal_data && PageChecked(page))
/*
* Delalloc doesn't support data journalling,
* but eventually maybe we'll lift this
* restriction.
*/
if (unlikely(journal_data && PageChecked(page)))
err = __ext4_journalled_writepage(page, len);
else if (buffer_uninit(page_bufs)) {
ext4_set_bh_endio(page_bufs, inode);
err = block_write_full_page_endio(page,
noalloc_get_block_write,
mpd->wbc, ext4_end_io_buffer_write);
} else
err = block_write_full_page(page,
noalloc_get_block_write, mpd->wbc);
else
err = ext4_bio_write_page(&io_submit, page,
len, mpd->wbc);
if (!err)
mpd->pages_written++;
......@@ -2131,6 +2133,7 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
}
pagevec_release(&pvec);
}
ext4_io_submit(&io_submit);
return ret;
}
......@@ -3426,15 +3429,6 @@ ext4_readpages(struct file *file, struct address_space *mapping,
return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
}
static void ext4_free_io_end(ext4_io_end_t *io)
{
BUG_ON(!io);
if (io->page)
put_page(io->page);
iput(io->inode);
kfree(io);
}
static void ext4_invalidatepage_free_endio(struct page *page, unsigned long offset)
{
struct buffer_head *head, *bh;
......@@ -3639,68 +3633,6 @@ static void dump_completed_IO(struct inode * inode)
#endif
}
/*
* check a range of space and convert unwritten extents to written.
*/
static 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_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 = 0;
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);
}
/*
* This function is called from ext4_sync_file().
*
......@@ -3756,28 +3688,6 @@ int flush_completed_IO(struct inode *inode)
return (ret2 < 0) ? ret2 : 0;
}
static ext4_io_end_t *ext4_init_io_end (struct inode *inode, gfp_t flags)
{
ext4_io_end_t *io = NULL;
io = kmalloc(sizeof(*io), flags);
if (io) {
igrab(inode);
io->inode = inode;
io->flag = 0;
io->offset = 0;
io->size = 0;
io->page = NULL;
io->iocb = NULL;
io->result = 0;
INIT_WORK(&io->work, ext4_end_io_work);
INIT_LIST_HEAD(&io->list);
}
return io;
}
static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
ssize_t size, void *private, int ret,
bool is_async)
......@@ -3797,7 +3707,7 @@ static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
size);
/* if not aio dio with unwritten extents, just free io and return */
if (io_end->flag != EXT4_IO_UNWRITTEN){
if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
ext4_free_io_end(io_end);
iocb->private = NULL;
out:
......@@ -3842,7 +3752,7 @@ static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate)
goto out;
}
io_end->flag = EXT4_IO_UNWRITTEN;
io_end->flag = EXT4_IO_END_UNWRITTEN;
inode = io_end->inode;
/* Add the io_end to per-inode completed io list*/
......
/*
* 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 init_ext4_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 exit_ext4_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;
}