ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
{
struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = len };
struct kiocb kiocb;
ssize_t ret;
init_sync_kiocb(&kiocb, filp);
kiocb.ki_pos = *ppos;
kiocb.ki_left = len;
kiocb.ki_nbytes = len;
ret = filp->f_op->aio_write(&kiocb, &iov, 1, kiocb.ki_pos);
if (-EIOCBQUEUED == ret)
ret = wait_on_sync_kiocb(&kiocb);
*ppos = kiocb.ki_pos;
return ret;
}
static inline void iov_iter_init(struct iov_iter *i,
const struct iovec *iov, unsigned long nr_segs,
size_t count, size_t written)
{
i->iov = iov;
i->nr_segs = nr_segs;
i->iov_offset = 0;
i->count = count + written;
iov_iter_advance(i, written);
}
copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
static ssize_t generic_perform_write(struct file *file, struct iov_iter *i, loff_t pos){
struct address_space *mapping = file->f_mapping;
const struct address_space_operations *a_ops = mapping->a_ops;
long status = 0;
ssize_t written = 0;
unsigned int flags = 0;
if (segment_eq(get_fs(), KERNEL_DS))
flags |= AOP_FLAG_UNINTERRUPTIBLE;
do {
struct page *page;
unsigned long offset; /* Offset into pagecache page */
unsigned long bytes; /* Bytes to write to page */
size_t copied; /* Bytes copied from user */
void *fsdata;
offset = (pos & (PAGE_CACHE_SIZE - 1));
bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, iov_iter_count(i) );
again:
if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
status = -EFAULT;
break;
}
status = a_ops->write_begin(file, mapping, pos, bytes, flags,
&page, &fsdata);
if (unlikely(status))
break;
if (mapping_writably_mapped(mapping))
flush_dcache_page(page);
pagefault_disable();
copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
pagefault_enable();
flush_dcache_page(page);
} while (iov_iter_count(i));
return written ? written : status;
}
head = create_page_buffers(page, inode, 0);
int __block_write_begin(struct page *page, loff_t pos, unsigned len,
get_block_t *get_block)
{
unsigned from = pos & (PAGE_CACHE_SIZE - 1);
unsigned to = from + len;
struct inode *inode = page->mapping->host;
unsigned block_start, block_end;
sector_t block;
int err = 0;
unsigned blocksize, bbits;
struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
BUG_ON(!PageLocked(page));
BUG_ON(from > PAGE_CACHE_SIZE);
BUG_ON(to > PAGE_CACHE_SIZE);
BUG_ON(from > to);
head = create_page_buffers(page, inode, 0);
}
memset(&io_submit, 0, sizeof(io_submit));
ret = ext4_bio_write_page(&io_submit, page, len, wbc);
ext4_io_submit(&io_submit);
static int ext4_writepage(struct page *page,
struct writeback_control *wbc)
{
int ret = 0;
loff_t size;
unsigned int len;
struct buffer_head *page_bufs = NULL;
struct inode *inode = page->mapping->host;
struct ext4_io_submit io_submit;
trace_ext4_writepage(page);
size = i_size_read(inode);
if (page->index == size >> PAGE_CACHE_SHIFT)
len = size & ~PAGE_CACHE_MASK;
else
len = PAGE_CACHE_SIZE;
page_bufs = page_buffers(page);
/*
* We cannot do block allocation or other extent handling in this
* function. If there are buffers needing that, we have to redirty
* the page. But we may reach here when we do a journal commit via
* journal_submit_inode_data_buffers() and in that case we must write
* allocated buffers to achieve data=ordered mode guarantees.
*/
if (ext4_walk_page_buffers(NULL, page_bufs, 0, len, NULL,
ext4_bh_delay_or_unwritten)) {
redirty_page_for_writepage(wbc, page);
if (current->flags & PF_MEMALLOC) {
/*
* For memory cleaning there's no point in writing only
* some buffers. So just bail out. Warn if we came here
* from direct reclaim.
*/
WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD))
== PF_MEMALLOC);
unlock_page(page);
return 0;
}
}
if (PageChecked(page) && ext4_should_journal_data(inode))
/*
* It's mmapped pagecache. Add buffers and journal it. There
* doesn't seem much point in redirtying the page here.
*/
return __ext4_journalled_writepage(page, len);
memset(&io_submit, 0, sizeof(io_submit));
ret = ext4_bio_write_page(&io_submit, page, len, wbc);
ext4_io_submit(&io_submit);
return ret;
}
int ioprio = cic->icq.ioc->ioprio;
static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
{
int ioprio = cic->icq.ioc->ioprio;
struct cfq_data *cfqd = cic_to_cfqd(cic);
struct cfq_queue *cfqq;
/*
* Check whether ioprio has changed. The condition may trigger
* spuriously on a newly created cic but there's no harm.
*/
if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
return;
cfqq = cic->cfqq[BLK_RW_ASYNC];
if (cfqq) {
struct cfq_queue *new_cfqq;
new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio,
GFP_ATOMIC);
if (new_cfqq) {
cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
cfq_put_queue(cfqq);
}
}
cfqq = cic->cfqq[BLK_RW_SYNC];
if (cfqq)
cfq_mark_cfqq_prio_changed(cfqq);
cic->ioprio = ioprio;
}