mirror of https://gitee.com/openkylin/linux.git
[PATCH] relay: consolidate sendfile() and read() code
Signed-off-by: Jens Axboe <axboe@suse.de>
This commit is contained in:
Tom Zanussi
Jens Axboe
parent
221415d762
commit
6dac40a7ce
203
kernel/relay.c
203
kernel/relay.c
|
|
@ -866,131 +866,138 @@ static size_t relay_file_read_end_pos(struct rchan_buf *buf,
|
|||
}
|
||||
|
||||
/**
|
||||
* relay_file_read - read file op for relay files
|
||||
* @filp: the file
|
||||
* @buffer: the userspace buffer
|
||||
* @count: number of bytes to read
|
||||
* @ppos: position to read from
|
||||
*
|
||||
* Reads count bytes or the number of bytes available in the
|
||||
* current sub-buffer being read, whichever is smaller.
|
||||
* subbuf_read_actor - read up to one subbuf's worth of data
|
||||
*/
|
||||
static ssize_t relay_file_read(struct file *filp,
|
||||
char __user *buffer,
|
||||
size_t count,
|
||||
loff_t *ppos)
|
||||
static int subbuf_read_actor(size_t read_start,
|
||||
struct rchan_buf *buf,
|
||||
size_t avail,
|
||||
read_descriptor_t *desc,
|
||||
read_actor_t actor)
|
||||
{
|
||||
struct rchan_buf *buf = filp->private_data;
|
||||
struct inode *inode = filp->f_dentry->d_inode;
|
||||
size_t read_start, avail;
|
||||
ssize_t ret = 0;
|
||||
void *from;
|
||||
|
||||
mutex_lock(&inode->i_mutex);
|
||||
if(!relay_file_read_avail(buf, *ppos))
|
||||
goto out;
|
||||
|
||||
read_start = relay_file_read_start_pos(*ppos, buf);
|
||||
avail = relay_file_read_subbuf_avail(read_start, buf);
|
||||
if (!avail)
|
||||
goto out;
|
||||
int ret = 0;
|
||||
|
||||
from = buf->start + read_start;
|
||||
ret = count = min(count, avail);
|
||||
if (copy_to_user(buffer, from, count)) {
|
||||
ret = -EFAULT;
|
||||
goto out;
|
||||
ret = avail;
|
||||
if (copy_to_user(desc->arg.data, from, avail)) {
|
||||
desc->error = -EFAULT;
|
||||
ret = 0;
|
||||
}
|
||||
relay_file_read_consume(buf, read_start, count);
|
||||
*ppos = relay_file_read_end_pos(buf, read_start, count);
|
||||
out:
|
||||
mutex_unlock(&inode->i_mutex);
|
||||
desc->arg.data += ret;
|
||||
desc->written += ret;
|
||||
desc->count -= ret;
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
static ssize_t relay_file_sendsubbuf(struct file *filp, loff_t *ppos,
|
||||
size_t count, read_actor_t actor,
|
||||
void *target)
|
||||
/**
|
||||
* subbuf_send_actor - send up to one subbuf's worth of data
|
||||
*/
|
||||
static int subbuf_send_actor(size_t read_start,
|
||||
struct rchan_buf *buf,
|
||||
size_t avail,
|
||||
read_descriptor_t *desc,
|
||||
read_actor_t actor)
|
||||
{
|
||||
struct rchan_buf *buf = filp->private_data;
|
||||
read_descriptor_t desc;
|
||||
size_t read_start, avail;
|
||||
unsigned long pidx, poff;
|
||||
unsigned int subbuf_pages;
|
||||
ssize_t ret = 0;
|
||||
int ret = 0;
|
||||
|
||||
if (!relay_file_read_avail(buf, *ppos))
|
||||
subbuf_pages = buf->chan->alloc_size >> PAGE_SHIFT;
|
||||
pidx = (read_start / PAGE_SIZE) % subbuf_pages;
|
||||
poff = read_start & ~PAGE_MASK;
|
||||
while (avail) {
|
||||
struct page *p = buf->page_array[pidx];
|
||||
unsigned int len;
|
||||
|
||||
len = PAGE_SIZE - poff;
|
||||
if (len > avail)
|
||||
len = avail;
|
||||
|
||||
len = actor(desc, p, poff, len);
|
||||
if (desc->error)
|
||||
break;
|
||||
|
||||
avail -= len;
|
||||
ret += len;
|
||||
poff = 0;
|
||||
pidx = (pidx + 1) % subbuf_pages;
|
||||
}
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
typedef int (*subbuf_actor_t) (size_t read_start,
|
||||
struct rchan_buf *buf,
|
||||
size_t avail,
|
||||
read_descriptor_t *desc,
|
||||
read_actor_t actor);
|
||||
|
||||
/**
|
||||
* relay_file_read_subbufs - read count bytes, bridging subbuf boundaries
|
||||
*/
|
||||
static inline ssize_t relay_file_read_subbufs(struct file *filp,
|
||||
loff_t *ppos,
|
||||
size_t count,
|
||||
subbuf_actor_t subbuf_actor,
|
||||
read_actor_t actor,
|
||||
void *target)
|
||||
{
|
||||
struct rchan_buf *buf = filp->private_data;
|
||||
size_t read_start, avail;
|
||||
read_descriptor_t desc;
|
||||
int ret;
|
||||
|
||||
if (!count)
|
||||
return 0;
|
||||
|
||||
read_start = relay_file_read_start_pos(*ppos, buf);
|
||||
avail = relay_file_read_subbuf_avail(read_start, buf);
|
||||
if (!avail)
|
||||
return 0;
|
||||
|
||||
count = min(count, avail);
|
||||
|
||||
desc.written = 0;
|
||||
desc.count = count;
|
||||
desc.arg.data = target;
|
||||
desc.error = 0;
|
||||
|
||||
subbuf_pages = buf->chan->alloc_size >> PAGE_SHIFT;
|
||||
pidx = (read_start / PAGE_SIZE) % subbuf_pages;
|
||||
poff = read_start & ~PAGE_MASK;
|
||||
while (count) {
|
||||
struct page *p = buf->page_array[pidx];
|
||||
unsigned int len;
|
||||
|
||||
len = PAGE_SIZE - poff;
|
||||
if (len > count)
|
||||
len = count;
|
||||
|
||||
len = actor(&desc, p, poff, len);
|
||||
|
||||
if (desc.error) {
|
||||
if (!ret)
|
||||
ret = desc.error;
|
||||
mutex_lock(&filp->f_dentry->d_inode->i_mutex);
|
||||
do {
|
||||
if (!relay_file_read_avail(buf, *ppos))
|
||||
break;
|
||||
|
||||
read_start = relay_file_read_start_pos(*ppos, buf);
|
||||
avail = relay_file_read_subbuf_avail(read_start, buf);
|
||||
if (!avail)
|
||||
break;
|
||||
|
||||
avail = min(desc.count, avail);
|
||||
ret = subbuf_actor(read_start, buf, avail, &desc, actor);
|
||||
if (desc.error < 0)
|
||||
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);
|
||||
mutex_unlock(&filp->f_dentry->d_inode->i_mutex);
|
||||
|
||||
count -= len;
|
||||
ret += len;
|
||||
poff = 0;
|
||||
pidx = (pidx + 1) % subbuf_pages;
|
||||
}
|
||||
|
||||
if (ret > 0) {
|
||||
relay_file_read_consume(buf, read_start, ret);
|
||||
*ppos = relay_file_read_end_pos(buf, read_start, ret);
|
||||
}
|
||||
|
||||
return ret;
|
||||
return desc.written;
|
||||
}
|
||||
|
||||
static ssize_t relay_file_sendfile(struct file *filp, loff_t *ppos,
|
||||
size_t count, read_actor_t actor,
|
||||
static ssize_t relay_file_read(struct file *filp,
|
||||
char __user *buffer,
|
||||
size_t count,
|
||||
loff_t *ppos)
|
||||
{
|
||||
return relay_file_read_subbufs(filp, ppos, count, subbuf_read_actor,
|
||||
NULL, buffer);
|
||||
}
|
||||
|
||||
static ssize_t relay_file_sendfile(struct file *filp,
|
||||
loff_t *ppos,
|
||||
size_t count,
|
||||
read_actor_t actor,
|
||||
void *target)
|
||||
{
|
||||
ssize_t sent = 0, ret = 0;
|
||||
|
||||
if (!count)
|
||||
return 0;
|
||||
|
||||
mutex_lock(&filp->f_dentry->d_inode->i_mutex);
|
||||
|
||||
do {
|
||||
ret = relay_file_sendsubbuf(filp, ppos, count, actor, target);
|
||||
if (ret < 0) {
|
||||
if (!sent)
|
||||
sent = ret;
|
||||
break;
|
||||
}
|
||||
count -= ret;
|
||||
sent += ret;
|
||||
} while (count && ret);
|
||||
|
||||
mutex_unlock(&filp->f_dentry->d_inode->i_mutex);
|
||||
return sent;
|
||||
return relay_file_read_subbufs(filp, ppos, count, subbuf_send_actor,
|
||||
actor, target);
|
||||
}
|
||||
|
||||
struct file_operations relay_file_operations = {
|
||||
|
|
|
|||
Loading…
Reference in New Issue