[PATCH -v2 1/6] pipe: make the maximum pipe size referable from kernel module

[Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>]

Make the maximum pipe size referable from a kernel module.

The /proc/sys/fs/pipe-max-size defines an upper limit for the
capacity of a pipe. It is also used as an upper limit of a
fuse read/write request size in this patch series. So, it
is necessary to make it referable from a kernel module.

Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Muthukumar R <muthur@gmail.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
---

 fs/pipe.c                 |    7 +++++++
 include/linux/pipe_fs_i.h |    3 +++
 2 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/fs/pipe.c b/fs/pipe.c
index 49c1065..f0f3768 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -36,6 +36,13 @@ unsigned int pipe_max_size = 1048576;
  */
 unsigned int pipe_min_size = PAGE_SIZE;
 
+/* get pipe_max_size */
+unsigned int pipe_get_max_size(void)
+{
+	return pipe_max_size;
+}
+EXPORT_SYMBOL(pipe_get_max_size);
+
 /*
  * We use a start+len construction, which provides full use of the 
  * allocated memory.
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index e1ac1ce..50a16dd 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -134,6 +134,9 @@ struct pipe_buf_operations {
    memory allocation, whereas PIPE_BUF makes atomicity guarantees.  */
 #define PIPE_SIZE		PAGE_SIZE
 
+/* get pipe_max_size */
+unsigned int pipe_get_max_size(void);
+
 /* Pipe lock and unlock operations */
 void pipe_lock(struct pipe_inode_info *);
 void pipe_unlock(struct pipe_inode_info *);