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-rw-r--r--kernel/relay.c175
1 files changed, 91 insertions, 84 deletions
diff --git a/kernel/relay.c b/kernel/relay.c
index fefe2b2a727..33345e73485 100644
--- a/kernel/relay.c
+++ b/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;
-
- if (!relay_file_read_avail(buf, *ppos))
- 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;
+ int ret = 0;
subbuf_pages = buf->chan->alloc_size >> PAGE_SHIFT;
pidx = (read_start / PAGE_SIZE) % subbuf_pages;
poff = read_start & ~PAGE_MASK;
- while (count) {
+ while (avail) {
struct page *p = buf->page_array[pidx];
unsigned int len;
len = PAGE_SIZE - poff;
- if (len > count)
- len = count;
+ if (len > avail)
+ len = avail;
- len = actor(&desc, p, poff, len);
-
- if (desc.error) {
- if (!ret)
- ret = desc.error;
+ len = actor(desc, p, poff, len);
+ if (desc->error)
break;
- }
- count -= len;
+ avail -= 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;
}
-static ssize_t relay_file_sendfile(struct file *filp, loff_t *ppos,
- size_t count, read_actor_t actor,
- void *target)
+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)
{
- ssize_t sent = 0, ret = 0;
+ struct rchan_buf *buf = filp->private_data;
+ size_t read_start, avail;
+ read_descriptor_t desc;
+ int ret;
if (!count)
return 0;
- mutex_lock(&filp->f_dentry->d_inode->i_mutex);
+ desc.written = 0;
+ desc.count = count;
+ desc.arg.data = target;
+ desc.error = 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;
+ 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;
- }
- count -= ret;
- sent += ret;
- } while (count && ret);
+ 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);
- return sent;
+
+ return desc.written;
+}
+
+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)
+{
+ return relay_file_read_subbufs(filp, ppos, count, subbuf_send_actor,
+ actor, target);
}
struct file_operations relay_file_operations = {