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alistair23-linux
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switch /dev/zero and /dev/full to ->read_iter() 

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
hifive-unleashed-5.1
Al Viro 2014-08-18 10:04:12 -04:00
parent a1f6dbac62
commit 13ba33e899
1 changed files with 17 additions and 47 deletions
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64
drivers/char/mem.c
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@ -622,53 +622,23 @@ static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
}
static ssize_t read_zero(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
size_t written;
if (!count)
return 0;
if (!access_ok(VERIFY_WRITE, buf, count))
return -EFAULT;
written = 0;
while (count) {
unsigned long unwritten;
size_t chunk = count;
if (chunk > PAGE_SIZE)
chunk = PAGE_SIZE; /* Just for latency reasons */
unwritten = __clear_user(buf, chunk);
written += chunk - unwritten;
if (unwritten)
break;
if (signal_pending(current))
return written ? written : -ERESTARTSYS;
buf += chunk;
count -= chunk;
cond_resched();
}
return written ? written : -EFAULT;
}
static ssize_t aio_read_zero(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
{
size_t written = 0;
unsigned long i;
ssize_t ret;
for (i = 0; i < nr_segs; i++) {
ret = read_zero(iocb->ki_filp, iov[i].iov_base, iov[i].iov_len,
&pos);
if (ret < 0)
break;
written += ret;
while (iov_iter_count(iter)) {
size_t chunk = iov_iter_count(iter), n;
if (chunk > PAGE_SIZE)
chunk = PAGE_SIZE; /* Just for latency reasons */
n = iov_iter_zero(chunk, iter);
if (!n && iov_iter_count(iter))
return written ? written : -EFAULT;
written += n;
if (signal_pending(current))
return written ? written : -ERESTARTSYS;
cond_resched();
}
return written ? written : -EFAULT;
return written;
}
static int mmap_zero(struct file *file, struct vm_area_struct *vma)
@ -738,7 +708,6 @@ static int open_port(struct inode *inode, struct file *filp)
#define zero_lseek null_lseek
#define full_lseek null_lseek
#define write_zero write_null
#define read_full read_zero
#define aio_write_zero aio_write_null
#define open_mem open_port
#define open_kmem open_mem
@ -783,9 +752,9 @@ static const struct file_operations port_fops = {
static const struct file_operations zero_fops = {
.llseek = zero_lseek,
.read = read_zero,
.read = new_sync_read,
.write = write_zero,
.aio_read = aio_read_zero,
.read_iter = read_iter_zero,
.aio_write = aio_write_zero,
.mmap = mmap_zero,
};
@ -802,7 +771,8 @@ static struct backing_dev_info zero_bdi = {
static const struct file_operations full_fops = {
.llseek = full_lseek,
.read = read_full,
.read = new_sync_read,
.read_iter = read_iter_zero,
.write = write_full,
};