}
EXPORT_SYMBOL(generic_pipe_buf_release);
+/* New data written to a pipe may be appended to a buffer with this type. */
static const struct pipe_buf_operations anon_pipe_buf_ops = {
- .can_merge = 1,
.confirm = generic_pipe_buf_confirm,
.release = anon_pipe_buf_release,
.steal = anon_pipe_buf_steal,
};
static const struct pipe_buf_operations anon_pipe_buf_nomerge_ops = {
- .can_merge = 0,
.confirm = generic_pipe_buf_confirm,
.release = anon_pipe_buf_release,
.steal = anon_pipe_buf_steal,
};
static const struct pipe_buf_operations packet_pipe_buf_ops = {
- .can_merge = 0,
.confirm = generic_pipe_buf_confirm,
.release = anon_pipe_buf_release,
.steal = anon_pipe_buf_steal,
.get = generic_pipe_buf_get,
};
+/**
+ * pipe_buf_mark_unmergeable - mark a &struct pipe_buffer as unmergeable
+ * @buf: the buffer to mark
+ *
+ * Description:
+ * This function ensures that no future writes will be merged into the
+ * given &struct pipe_buffer. This is necessary when multiple pipe buffers
+ * share the same backing page.
+ */
void pipe_buf_mark_unmergeable(struct pipe_buffer *buf)
{
if (buf->ops == &anon_pipe_buf_ops)
buf->ops = &anon_pipe_buf_nomerge_ops;
}
+static bool pipe_buf_can_merge(struct pipe_buffer *buf)
+{
+ return buf->ops == &anon_pipe_buf_ops;
+}
+
static ssize_t
pipe_read(struct kiocb *iocb, struct iov_iter *to)
{
struct pipe_buffer *buf = pipe->bufs + lastbuf;
int offset = buf->offset + buf->len;
- if (buf->ops->can_merge && offset + chars <= PAGE_SIZE) {
+ if (pipe_buf_can_merge(buf) && offset + chars <= PAGE_SIZE) {
ret = pipe_buf_confirm(pipe, buf);
if (ret)
goto out;
}
const struct pipe_buf_operations page_cache_pipe_buf_ops = {
- .can_merge = 0,
.confirm = page_cache_pipe_buf_confirm,
.release = page_cache_pipe_buf_release,
.steal = page_cache_pipe_buf_steal,
}
static const struct pipe_buf_operations user_page_pipe_buf_ops = {
- .can_merge = 0,
.confirm = generic_pipe_buf_confirm,
.release = page_cache_pipe_buf_release,
.steal = user_page_pipe_buf_steal,
EXPORT_SYMBOL(generic_file_splice_read);
const struct pipe_buf_operations default_pipe_buf_ops = {
- .can_merge = 0,
.confirm = generic_pipe_buf_confirm,
.release = generic_pipe_buf_release,
.steal = generic_pipe_buf_steal,
/* Pipe buffer operations for a socket and similar. */
const struct pipe_buf_operations nosteal_pipe_buf_ops = {
- .can_merge = 0,
.confirm = generic_pipe_buf_confirm,
.release = generic_pipe_buf_release,
.steal = generic_pipe_buf_nosteal,
* in fs/pipe.c for the pipe and generic variants of these hooks.
*/
struct pipe_buf_operations {
- /*
- * This is set to 1, if the generic pipe read/write may coalesce
- * data into an existing buffer. If this is set to 0, a new pipe
- * page segment is always used for new data.
- */
- int can_merge;
-
/*
* ->confirm() verifies that the data in the pipe buffer is there
* and that the contents are good. If the pages in the pipe belong
}
static const struct pipe_buf_operations relay_pipe_buf_ops = {
- .can_merge = 0,
.confirm = generic_pipe_buf_confirm,
.release = relay_pipe_buf_release,
.steal = generic_pipe_buf_steal,
}
static const struct pipe_buf_operations tracing_pipe_buf_ops = {
- .can_merge = 0,
.confirm = generic_pipe_buf_confirm,
.release = generic_pipe_buf_release,
.steal = generic_pipe_buf_steal,
/* Pipe buffer operations for a buffer. */
static const struct pipe_buf_operations buffer_pipe_buf_ops = {
- .can_merge = 0,
.confirm = generic_pipe_buf_confirm,
.release = buffer_pipe_buf_release,
.steal = generic_pipe_buf_steal,
}
static const struct pipe_buf_operations smc_pipe_ops = {
- .can_merge = 0,
.confirm = generic_pipe_buf_confirm,
.release = smc_rx_pipe_buf_release,
.steal = smc_rx_pipe_buf_nosteal,