Provide a helper, pipe_head_buf(), to get the current head buffer from a
pipe. Implement this as a wrapper around a more general function,
pipe_buf(), that gets a specified buffer.
Requested-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
cc: Jens Axboe <axboe@xxxxxxxxx>
cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
cc: John Hubbard <jhubbard@xxxxxxxxxx>
cc: David Hildenbrand <david@xxxxxxxxxx>
cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
cc: linux-block@xxxxxxxxxxxxxxx
cc: linux-fsdevel@xxxxxxxxxxxxxxx
cc: linux-mm@xxxxxxxxx
---
fs/splice.c | 9 +++------
include/linux/pipe_fs_i.h | 20 ++++++++++++++++++++
2 files changed, 23 insertions(+), 6 deletions(-)
diff --git a/fs/splice.c b/fs/splice.c
index 91b9e2cb9e03..7c0ff187f87a 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -295,7 +295,6 @@ static ssize_t direct_splice_read(struct file *in, loff_t *ppos,
struct bio_vec *bv;
struct kiocb kiocb;
struct page **pages;
- unsigned int head;
ssize_t ret;
size_t used, npages, chunk, remain, reclaim;
int i;
@@ -358,9 +357,8 @@ static ssize_t direct_splice_read(struct file *in, loff_t *ppos,
}
/* Push the remaining pages into the pipe. */
- head = pipe->head;
for (i = 0; i < npages; i++) {
- struct pipe_buffer *buf = &pipe->bufs[head & (pipe->ring_size - 1)];
+ struct pipe_buffer *buf = pipe_head_buf(pipe);
chunk = min_t(size_t, remain, PAGE_SIZE);
*buf = (struct pipe_buffer) {
@@ -369,10 +367,9 @@ static ssize_t direct_splice_read(struct file *in, loff_t *ppos,
.offset = 0,
.len = chunk,
};
- head++;
+ pipe->head++;
remain -= chunk;
}
- pipe->head = head;
kfree(bv);
return ret;
@@ -394,7 +391,7 @@ static size_t splice_folio_into_pipe(struct pipe_inode_info *pipe,
while (spliced < size &&
!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) {
- struct pipe_buffer *buf = &pipe->bufs[pipe->head & (pipe->ring_size - 1)];
+ struct pipe_buffer *buf = pipe_head_buf(pipe);
size_t part = min_t(size_t, PAGE_SIZE - offset, size - spliced);
*buf = (struct pipe_buffer) {
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 6cb65df3e3ba..d2c3f16cf6b1 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -156,6 +156,26 @@ static inline bool pipe_full(unsigned int head, unsigned int tail,
return pipe_occupancy(head, tail) >= limit;
}
+/**
+ * pipe_buf - Return the pipe buffer for the specified slot in the pipe ring
+ * @pipe: The pipe to access
+ * @slot: The slot of interest
+ */
+static inline struct pipe_buffer *pipe_buf(const struct pipe_inode_info *pipe,
+ unsigned int slot)
+{
+ return &pipe->bufs[slot & (pipe->ring_size - 1)];
+}
+
+/**
+ * pipe_head_buf - Return the pipe buffer at the head of the pipe ring
+ * @pipe: The pipe to access
+ */
+static inline struct pipe_buffer *pipe_head_buf(const struct pipe_inode_info *pipe)
+{
+ return pipe_buf(pipe, pipe->head);
+}
+
/**
* pipe_buf_get - get a reference to a pipe_buffer
* @pipe: the pipe that the buffer belongs to
