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relay: simplify relay_file_read()

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to hell with actors...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2016-09-25 22:52:02 -04:00
parent 523ac9afc7
commit a7c2242166
1 changed files with 20 additions and 58 deletions
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78
kernel/relay.c
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@ -1121,51 +1121,23 @@ static size_t relay_file_read_end_pos(struct rchan_buf *buf,
return end_pos;
}
/*
* subbuf_read_actor - read up to one subbuf's worth of data
*/
static int subbuf_read_actor(size_t read_start,
struct rchan_buf *buf,
size_t avail,
read_descriptor_t *desc)
{
void *from;
int ret = 0;
from = buf->start + read_start;
ret = avail;
if (copy_to_user(desc->arg.buf, from, avail)) {
desc->error = -EFAULT;
ret = 0;
}
desc->arg.data += ret;
desc->written += ret;
desc->count -= ret;
return ret;
}
typedef int (*subbuf_actor_t) (size_t read_start,
struct rchan_buf *buf,
size_t avail,
read_descriptor_t *desc);
/*
* relay_file_read_subbufs - read count bytes, bridging subbuf boundaries
*/
static ssize_t relay_file_read_subbufs(struct file *filp, loff_t *ppos,
subbuf_actor_t subbuf_actor,
read_descriptor_t *desc)
static ssize_t relay_file_read(struct file *filp,
char __user *buffer,
size_t count,
loff_t *ppos)
{
struct rchan_buf *buf = filp->private_data;
size_t read_start, avail;
size_t written = 0;
int ret;
if (!desc->count)
if (!count)
return 0;
inode_lock(file_inode(filp));
do {
void *from;
if (!relay_file_read_avail(buf, *ppos))
break;
@ -1174,32 +1146,22 @@ static ssize_t relay_file_read_subbufs(struct file *filp, loff_t *ppos,
if (!avail)
break;
avail = min(desc->count, avail);
ret = subbuf_actor(read_start, buf, avail, desc);
if (desc->error < 0)
avail = min(count, avail);
from = buf->start + read_start;
ret = avail;
if (copy_to_user(buffer, from, avail))
break;
if (ret) {
relay_file_read_consume(buf, read_start, ret);
*ppos = relay_file_read_end_pos(buf, read_start, ret);
}
} while (desc->count && ret);
buffer += ret;
written += ret;
count -= ret;
relay_file_read_consume(buf, read_start, ret);
*ppos = relay_file_read_end_pos(buf, read_start, ret);
} while (count);
inode_unlock(file_inode(filp));
return desc->written;
}
static ssize_t relay_file_read(struct file *filp,
char __user *buffer,
size_t count,
loff_t *ppos)
{
read_descriptor_t desc;
desc.written = 0;
desc.count = count;
desc.arg.buf = buffer;
desc.error = 0;
return relay_file_read_subbufs(filp, ppos, subbuf_read_actor, &desc);
return written;
}
static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed)