summaryrefslogtreecommitdiff
path: root/include/linux/pipe_fs_i.h
diff options
context:
space:
mode:
Diffstat (limited to 'include/linux/pipe_fs_i.h')
-rw-r--r--include/linux/pipe_fs_i.h40
1 files changed, 21 insertions, 19 deletions
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index ae58fad7f1e0..0c31b9461262 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -8,6 +8,7 @@
#define PIPE_BUF_FLAG_ATOMIC 0x02 /* was atomically mapped */
#define PIPE_BUF_FLAG_GIFT 0x04 /* page is a gift */
#define PIPE_BUF_FLAG_PACKET 0x08 /* read() as a packet */
+#define PIPE_BUF_FLAG_CAN_MERGE 0x10 /* can merge buffers */
/**
* struct pipe_buffer - a linux kernel pipe buffer
@@ -69,11 +70,11 @@ struct pipe_inode_info {
* Note on the nesting of these functions:
*
* ->confirm()
- * ->steal()
+ * ->try_steal()
*
- * That is, ->steal() must be called on a confirmed buffer.
- * See below for the meaning of each operation. Also see kerneldoc
- * in fs/pipe.c for the pipe and generic variants of these hooks.
+ * That is, ->try_steal() must be called on a confirmed buffer. See below for
+ * the meaning of each operation. Also see the kerneldoc in fs/pipe.c for the
+ * pipe and generic variants of these hooks.
*/
struct pipe_buf_operations {
/*
@@ -81,7 +82,7 @@ struct pipe_buf_operations {
* and that the contents are good. If the pages in the pipe belong
* to a file system, we may need to wait for IO completion in this
* hook. Returns 0 for good, or a negative error value in case of
- * error.
+ * error. If not present all pages are considered good.
*/
int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *);
@@ -93,13 +94,13 @@ struct pipe_buf_operations {
/*
* Attempt to take ownership of the pipe buffer and its contents.
- * ->steal() returns 0 for success, in which case the contents
- * of the pipe (the buf->page) is locked and now completely owned
- * by the caller. The page may then be transferred to a different
- * mapping, the most often used case is insertion into different
- * file address space cache.
+ * ->try_steal() returns %true for success, in which case the contents
+ * of the pipe (the buf->page) is locked and now completely owned by the
+ * caller. The page may then be transferred to a different mapping, the
+ * most often used case is insertion into different file address space
+ * cache.
*/
- int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
+ bool (*try_steal)(struct pipe_inode_info *, struct pipe_buffer *);
/*
* Get a reference to the pipe buffer.
@@ -194,18 +195,22 @@ static inline void pipe_buf_release(struct pipe_inode_info *pipe,
static inline int pipe_buf_confirm(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
+ if (!buf->ops->confirm)
+ return 0;
return buf->ops->confirm(pipe, buf);
}
/**
- * pipe_buf_steal - attempt to take ownership of a pipe_buffer
+ * pipe_buf_try_steal - attempt to take ownership of a pipe_buffer
* @pipe: the pipe that the buffer belongs to
* @buf: the buffer to attempt to steal
*/
-static inline int pipe_buf_steal(struct pipe_inode_info *pipe,
- struct pipe_buffer *buf)
+static inline bool pipe_buf_try_steal(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf)
{
- return buf->ops->steal(pipe, buf);
+ if (!buf->ops->try_steal)
+ return false;
+ return buf->ops->try_steal(pipe, buf);
}
/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
@@ -229,11 +234,8 @@ void free_pipe_info(struct pipe_inode_info *);
/* Generic pipe buffer ops functions */
bool generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
-int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
-int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
-int generic_pipe_buf_nosteal(struct pipe_inode_info *, struct pipe_buffer *);
+bool generic_pipe_buf_try_steal(struct pipe_inode_info *, struct pipe_buffer *);
void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
-void pipe_buf_mark_unmergeable(struct pipe_buffer *buf);
extern const struct pipe_buf_operations nosteal_pipe_buf_ops;