![Tao Ma](/assets/img/avatar_default.png)
EXT4_IO_END_UNWRITTEN flag set and the increase of i_aiodio_unwritten
should be done simultaneously since ext4_end_io_nolock always clear
the flag and decrease the counter in the same time.
We have found some bugs that the flag is set while leaving
i_aiodio_unwritten unchanged(commit 32c80b32c0
). So this patch just tries
to create a helper function to wrap them to avoid any future bug.
The idea is inspired by Eric.
Cc: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
416 lines
11 KiB
C
416 lines
11 KiB
C
/*
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* linux/fs/ext4/page-io.c
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*
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* This contains the new page_io functions for ext4
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*
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* Written by Theodore Ts'o, 2010.
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*/
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/time.h>
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#include <linux/jbd2.h>
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#include <linux/highuid.h>
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#include <linux/pagemap.h>
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#include <linux/quotaops.h>
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#include <linux/string.h>
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#include <linux/buffer_head.h>
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#include <linux/writeback.h>
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#include <linux/pagevec.h>
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#include <linux/mpage.h>
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#include <linux/namei.h>
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#include <linux/uio.h>
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#include <linux/bio.h>
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#include <linux/workqueue.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include "ext4_jbd2.h"
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#include "xattr.h"
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#include "acl.h"
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#include "ext4_extents.h"
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static struct kmem_cache *io_page_cachep, *io_end_cachep;
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int __init ext4_init_pageio(void)
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{
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io_page_cachep = KMEM_CACHE(ext4_io_page, SLAB_RECLAIM_ACCOUNT);
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if (io_page_cachep == NULL)
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return -ENOMEM;
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io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
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if (io_end_cachep == NULL) {
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kmem_cache_destroy(io_page_cachep);
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return -ENOMEM;
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}
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return 0;
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}
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void ext4_exit_pageio(void)
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{
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kmem_cache_destroy(io_end_cachep);
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kmem_cache_destroy(io_page_cachep);
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}
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void ext4_ioend_wait(struct inode *inode)
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{
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wait_queue_head_t *wq = ext4_ioend_wq(inode);
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wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0));
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}
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static void put_io_page(struct ext4_io_page *io_page)
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{
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if (atomic_dec_and_test(&io_page->p_count)) {
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end_page_writeback(io_page->p_page);
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put_page(io_page->p_page);
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kmem_cache_free(io_page_cachep, io_page);
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}
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}
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void ext4_free_io_end(ext4_io_end_t *io)
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{
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int i;
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BUG_ON(!io);
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if (io->page)
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put_page(io->page);
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for (i = 0; i < io->num_io_pages; i++)
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put_io_page(io->pages[i]);
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io->num_io_pages = 0;
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if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count))
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wake_up_all(ext4_ioend_wq(io->inode));
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kmem_cache_free(io_end_cachep, io);
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}
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/*
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* check a range of space and convert unwritten extents to written.
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*
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* Called with inode->i_mutex; we depend on this when we manipulate
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* io->flag, since we could otherwise race with ext4_flush_completed_IO()
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*/
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int ext4_end_io_nolock(ext4_io_end_t *io)
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{
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struct inode *inode = io->inode;
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loff_t offset = io->offset;
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ssize_t size = io->size;
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int ret = 0;
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ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
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"list->prev 0x%p\n",
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io, inode->i_ino, io->list.next, io->list.prev);
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ret = ext4_convert_unwritten_extents(inode, offset, size);
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if (ret < 0) {
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ext4_msg(inode->i_sb, KERN_EMERG,
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"failed to convert unwritten extents to written "
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"extents -- potential data loss! "
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"(inode %lu, offset %llu, size %zd, error %d)",
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inode->i_ino, offset, size, ret);
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}
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if (io->iocb)
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aio_complete(io->iocb, io->result, 0);
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/* Wake up anyone waiting on unwritten extent conversion */
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if (atomic_dec_and_test(&EXT4_I(inode)->i_aiodio_unwritten))
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wake_up_all(ext4_ioend_wq(io->inode));
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return ret;
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}
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/*
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* work on completed aio dio IO, to convert unwritten extents to extents
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*/
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static void ext4_end_io_work(struct work_struct *work)
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{
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ext4_io_end_t *io = container_of(work, ext4_io_end_t, work);
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struct inode *inode = io->inode;
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struct ext4_inode_info *ei = EXT4_I(inode);
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unsigned long flags;
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spin_lock_irqsave(&ei->i_completed_io_lock, flags);
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if (list_empty(&io->list)) {
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spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
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goto free;
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}
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if (!mutex_trylock(&inode->i_mutex)) {
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spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
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/*
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* Requeue the work instead of waiting so that the work
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* items queued after this can be processed.
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*/
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queue_work(EXT4_SB(inode->i_sb)->dio_unwritten_wq, &io->work);
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/*
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* To prevent the ext4-dio-unwritten thread from keeping
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* requeueing end_io requests and occupying cpu for too long,
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* yield the cpu if it sees an end_io request that has already
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* been requeued.
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*/
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if (io->flag & EXT4_IO_END_QUEUED)
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yield();
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io->flag |= EXT4_IO_END_QUEUED;
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return;
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}
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list_del_init(&io->list);
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spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
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(void) ext4_end_io_nolock(io);
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mutex_unlock(&inode->i_mutex);
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free:
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ext4_free_io_end(io);
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}
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ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
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{
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ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
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if (io) {
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atomic_inc(&EXT4_I(inode)->i_ioend_count);
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io->inode = inode;
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INIT_WORK(&io->work, ext4_end_io_work);
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INIT_LIST_HEAD(&io->list);
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}
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return io;
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}
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/*
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* Print an buffer I/O error compatible with the fs/buffer.c. This
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* provides compatibility with dmesg scrapers that look for a specific
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* buffer I/O error message. We really need a unified error reporting
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* structure to userspace ala Digital Unix's uerf system, but it's
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* probably not going to happen in my lifetime, due to LKML politics...
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*/
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static void buffer_io_error(struct buffer_head *bh)
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{
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char b[BDEVNAME_SIZE];
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printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
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bdevname(bh->b_bdev, b),
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(unsigned long long)bh->b_blocknr);
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}
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static void ext4_end_bio(struct bio *bio, int error)
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{
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ext4_io_end_t *io_end = bio->bi_private;
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struct workqueue_struct *wq;
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struct inode *inode;
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unsigned long flags;
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int i;
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sector_t bi_sector = bio->bi_sector;
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BUG_ON(!io_end);
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bio->bi_private = NULL;
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bio->bi_end_io = NULL;
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if (test_bit(BIO_UPTODATE, &bio->bi_flags))
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error = 0;
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bio_put(bio);
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for (i = 0; i < io_end->num_io_pages; i++) {
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struct page *page = io_end->pages[i]->p_page;
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struct buffer_head *bh, *head;
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loff_t offset;
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loff_t io_end_offset;
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if (error) {
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SetPageError(page);
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set_bit(AS_EIO, &page->mapping->flags);
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head = page_buffers(page);
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BUG_ON(!head);
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io_end_offset = io_end->offset + io_end->size;
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offset = (sector_t) page->index << PAGE_CACHE_SHIFT;
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bh = head;
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do {
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if ((offset >= io_end->offset) &&
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(offset+bh->b_size <= io_end_offset))
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buffer_io_error(bh);
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offset += bh->b_size;
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bh = bh->b_this_page;
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} while (bh != head);
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}
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put_io_page(io_end->pages[i]);
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}
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io_end->num_io_pages = 0;
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inode = io_end->inode;
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if (error) {
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io_end->flag |= EXT4_IO_END_ERROR;
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ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
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"(offset %llu size %ld starting block %llu)",
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inode->i_ino,
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(unsigned long long) io_end->offset,
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(long) io_end->size,
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(unsigned long long)
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bi_sector >> (inode->i_blkbits - 9));
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}
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if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
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ext4_free_io_end(io_end);
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return;
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}
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/* Add the io_end to per-inode completed io list*/
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spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
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list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list);
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spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);
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wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq;
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/* queue the work to convert unwritten extents to written */
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queue_work(wq, &io_end->work);
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}
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void ext4_io_submit(struct ext4_io_submit *io)
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{
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struct bio *bio = io->io_bio;
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if (bio) {
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bio_get(io->io_bio);
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submit_bio(io->io_op, io->io_bio);
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BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
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bio_put(io->io_bio);
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}
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io->io_bio = NULL;
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io->io_op = 0;
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io->io_end = NULL;
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}
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static int io_submit_init(struct ext4_io_submit *io,
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struct inode *inode,
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struct writeback_control *wbc,
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struct buffer_head *bh)
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{
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ext4_io_end_t *io_end;
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struct page *page = bh->b_page;
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int nvecs = bio_get_nr_vecs(bh->b_bdev);
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struct bio *bio;
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io_end = ext4_init_io_end(inode, GFP_NOFS);
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if (!io_end)
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return -ENOMEM;
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bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
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bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
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bio->bi_bdev = bh->b_bdev;
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bio->bi_private = io->io_end = io_end;
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bio->bi_end_io = ext4_end_bio;
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io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
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io->io_bio = bio;
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io->io_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE);
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io->io_next_block = bh->b_blocknr;
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return 0;
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}
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static int io_submit_add_bh(struct ext4_io_submit *io,
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struct ext4_io_page *io_page,
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struct inode *inode,
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struct writeback_control *wbc,
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struct buffer_head *bh)
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{
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ext4_io_end_t *io_end;
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int ret;
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if (buffer_new(bh)) {
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clear_buffer_new(bh);
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unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
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}
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if (!buffer_mapped(bh) || buffer_delay(bh)) {
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if (!buffer_mapped(bh))
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clear_buffer_dirty(bh);
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if (io->io_bio)
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ext4_io_submit(io);
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return 0;
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}
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if (io->io_bio && bh->b_blocknr != io->io_next_block) {
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submit_and_retry:
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ext4_io_submit(io);
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}
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if (io->io_bio == NULL) {
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ret = io_submit_init(io, inode, wbc, bh);
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if (ret)
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return ret;
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}
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io_end = io->io_end;
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if ((io_end->num_io_pages >= MAX_IO_PAGES) &&
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(io_end->pages[io_end->num_io_pages-1] != io_page))
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goto submit_and_retry;
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if (buffer_uninit(bh))
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ext4_set_io_unwritten_flag(inode, io_end);
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io->io_end->size += bh->b_size;
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io->io_next_block++;
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ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
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if (ret != bh->b_size)
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goto submit_and_retry;
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if ((io_end->num_io_pages == 0) ||
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(io_end->pages[io_end->num_io_pages-1] != io_page)) {
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io_end->pages[io_end->num_io_pages++] = io_page;
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atomic_inc(&io_page->p_count);
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}
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return 0;
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}
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int ext4_bio_write_page(struct ext4_io_submit *io,
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struct page *page,
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int len,
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struct writeback_control *wbc)
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{
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struct inode *inode = page->mapping->host;
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unsigned block_start, block_end, blocksize;
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struct ext4_io_page *io_page;
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struct buffer_head *bh, *head;
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int ret = 0;
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blocksize = 1 << inode->i_blkbits;
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BUG_ON(!PageLocked(page));
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BUG_ON(PageWriteback(page));
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io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS);
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if (!io_page) {
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set_page_dirty(page);
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unlock_page(page);
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return -ENOMEM;
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}
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io_page->p_page = page;
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atomic_set(&io_page->p_count, 1);
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get_page(page);
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set_page_writeback(page);
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ClearPageError(page);
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for (bh = head = page_buffers(page), block_start = 0;
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bh != head || !block_start;
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block_start = block_end, bh = bh->b_this_page) {
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block_end = block_start + blocksize;
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if (block_start >= len) {
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clear_buffer_dirty(bh);
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set_buffer_uptodate(bh);
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continue;
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}
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clear_buffer_dirty(bh);
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ret = io_submit_add_bh(io, io_page, inode, wbc, bh);
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if (ret) {
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/*
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* We only get here on ENOMEM. Not much else
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* we can do but mark the page as dirty, and
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* better luck next time.
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*/
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set_page_dirty(page);
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break;
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}
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}
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unlock_page(page);
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/*
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* If the page was truncated before we could do the writeback,
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* or we had a memory allocation error while trying to write
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* the first buffer head, we won't have submitted any pages for
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* I/O. In that case we need to make sure we've cleared the
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* PageWriteback bit from the page to prevent the system from
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* wedging later on.
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*/
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put_io_page(io_page);
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return ret;
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}
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