[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
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@ -866,131 +866,138 @@ static size_t relay_file_read_end_pos(struct rchan_buf *buf,
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}
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/**
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* relay_file_read - read file op for relay files
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* @filp: the file
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* @buffer: the userspace buffer
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* @count: number of bytes to read
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* @ppos: position to read from
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*
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* Reads count bytes or the number of bytes available in the
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* current sub-buffer being read, whichever is smaller.
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* subbuf_read_actor - read up to one subbuf's worth of data
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*/
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static ssize_t relay_file_read(struct file *filp,
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char __user *buffer,
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size_t count,
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loff_t *ppos)
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static int subbuf_read_actor(size_t read_start,
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struct rchan_buf *buf,
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size_t avail,
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read_descriptor_t *desc,
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read_actor_t actor)
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{
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struct rchan_buf *buf = filp->private_data;
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struct inode *inode = filp->f_dentry->d_inode;
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size_t read_start, avail;
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ssize_t ret = 0;
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void *from;
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mutex_lock(&inode->i_mutex);
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if(!relay_file_read_avail(buf, *ppos))
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goto out;
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read_start = relay_file_read_start_pos(*ppos, buf);
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avail = relay_file_read_subbuf_avail(read_start, buf);
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if (!avail)
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goto out;
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int ret = 0;
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from = buf->start + read_start;
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ret = count = min(count, avail);
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if (copy_to_user(buffer, from, count)) {
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ret = -EFAULT;
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goto out;
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ret = avail;
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if (copy_to_user(desc->arg.data, from, avail)) {
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desc->error = -EFAULT;
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ret = 0;
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}
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relay_file_read_consume(buf, read_start, count);
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*ppos = relay_file_read_end_pos(buf, read_start, count);
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out:
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mutex_unlock(&inode->i_mutex);
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desc->arg.data += ret;
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desc->written += ret;
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desc->count -= ret;
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return ret;
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}
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static ssize_t relay_file_sendsubbuf(struct file *filp, loff_t *ppos,
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size_t count, read_actor_t actor,
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void *target)
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/**
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* subbuf_send_actor - send up to one subbuf's worth of data
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*/
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static int subbuf_send_actor(size_t read_start,
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struct rchan_buf *buf,
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size_t avail,
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read_descriptor_t *desc,
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read_actor_t actor)
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{
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struct rchan_buf *buf = filp->private_data;
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read_descriptor_t desc;
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size_t read_start, avail;
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unsigned long pidx, poff;
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unsigned int subbuf_pages;
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ssize_t ret = 0;
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int ret = 0;
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if (!relay_file_read_avail(buf, *ppos))
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subbuf_pages = buf->chan->alloc_size >> PAGE_SHIFT;
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pidx = (read_start / PAGE_SIZE) % subbuf_pages;
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poff = read_start & ~PAGE_MASK;
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while (avail) {
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struct page *p = buf->page_array[pidx];
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unsigned int len;
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len = PAGE_SIZE - poff;
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if (len > avail)
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len = avail;
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len = actor(desc, p, poff, len);
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if (desc->error)
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break;
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avail -= len;
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ret += len;
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poff = 0;
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pidx = (pidx + 1) % subbuf_pages;
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}
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return ret;
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}
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typedef int (*subbuf_actor_t) (size_t read_start,
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struct rchan_buf *buf,
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size_t avail,
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read_descriptor_t *desc,
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read_actor_t actor);
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/**
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* relay_file_read_subbufs - read count bytes, bridging subbuf boundaries
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*/
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static inline ssize_t relay_file_read_subbufs(struct file *filp,
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loff_t *ppos,
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size_t count,
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subbuf_actor_t subbuf_actor,
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read_actor_t actor,
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void *target)
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{
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struct rchan_buf *buf = filp->private_data;
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size_t read_start, avail;
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read_descriptor_t desc;
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int ret;
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if (!count)
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return 0;
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read_start = relay_file_read_start_pos(*ppos, buf);
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avail = relay_file_read_subbuf_avail(read_start, buf);
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if (!avail)
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return 0;
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count = min(count, avail);
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desc.written = 0;
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desc.count = count;
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desc.arg.data = target;
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desc.error = 0;
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subbuf_pages = buf->chan->alloc_size >> PAGE_SHIFT;
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pidx = (read_start / PAGE_SIZE) % subbuf_pages;
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poff = read_start & ~PAGE_MASK;
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while (count) {
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struct page *p = buf->page_array[pidx];
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unsigned int len;
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len = PAGE_SIZE - poff;
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if (len > count)
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len = count;
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len = actor(&desc, p, poff, len);
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if (desc.error) {
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if (!ret)
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ret = desc.error;
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mutex_lock(&filp->f_dentry->d_inode->i_mutex);
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do {
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if (!relay_file_read_avail(buf, *ppos))
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break;
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read_start = relay_file_read_start_pos(*ppos, buf);
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avail = relay_file_read_subbuf_avail(read_start, buf);
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if (!avail)
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break;
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avail = min(desc.count, avail);
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ret = subbuf_actor(read_start, buf, avail, &desc, actor);
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if (desc.error < 0)
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break;
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if (ret) {
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relay_file_read_consume(buf, read_start, ret);
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*ppos = relay_file_read_end_pos(buf, read_start, ret);
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}
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} while (desc.count && ret);
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mutex_unlock(&filp->f_dentry->d_inode->i_mutex);
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count -= len;
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ret += len;
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poff = 0;
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pidx = (pidx + 1) % subbuf_pages;
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}
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if (ret > 0) {
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relay_file_read_consume(buf, read_start, ret);
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*ppos = relay_file_read_end_pos(buf, read_start, ret);
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}
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return ret;
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return desc.written;
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}
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static ssize_t relay_file_sendfile(struct file *filp, loff_t *ppos,
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size_t count, read_actor_t actor,
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static ssize_t relay_file_read(struct file *filp,
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char __user *buffer,
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size_t count,
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loff_t *ppos)
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{
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return relay_file_read_subbufs(filp, ppos, count, subbuf_read_actor,
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NULL, buffer);
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}
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static ssize_t relay_file_sendfile(struct file *filp,
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loff_t *ppos,
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size_t count,
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read_actor_t actor,
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void *target)
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{
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ssize_t sent = 0, ret = 0;
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if (!count)
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return 0;
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mutex_lock(&filp->f_dentry->d_inode->i_mutex);
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do {
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ret = relay_file_sendsubbuf(filp, ppos, count, actor, target);
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if (ret < 0) {
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if (!sent)
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sent = ret;
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break;
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}
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count -= ret;
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sent += ret;
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} while (count && ret);
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mutex_unlock(&filp->f_dentry->d_inode->i_mutex);
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return sent;
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return relay_file_read_subbufs(filp, ppos, count, subbuf_send_actor,
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actor, target);
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}
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struct file_operations relay_file_operations = {
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