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Date: Fri, 25 Feb 2022 19:54:31 +0100
From: Max Kellermann <max.kellermann@...il.com>
To: viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Max Kellermann <max.kellermann@...il.com>
Subject: [PATCH 4/4] pipe_fs_i.h: add pipe_buf_init()
Adds one central function which shall be used to initialize a newly
allocated struct pipe_buffer. This shall make the pipe code more
robust for the next time the pipe_buffer struct gets modified, to
avoid leaving new members uninitialized. Instead, adding new members
should also add a new pipe_buf_init() parameter, which causes
compile-time errors in call sites that were not adapted.
This commit doesn't refactor fs/fuse/dev.c because this code looks
obscure to me; it initializes pipe_buffers incrementally through a
variety of functions, too complicated for me to understand.
To: Alexander Viro <viro@...iv.linux.org.uk>
To: linux-fsdevel@...r.kernel.org
To: linux-kernel@...r.kernel.org
Signed-off-by: Max Kellermann <max.kellermann@...il.com>
---
fs/pipe.c | 11 +++--------
fs/splice.c | 9 ++++-----
include/linux/pipe_fs_i.h | 20 ++++++++++++++++++++
kernel/watch_queue.c | 8 +++-----
lib/iov_iter.c | 13 +++----------
5 files changed, 33 insertions(+), 28 deletions(-)
diff --git a/fs/pipe.c b/fs/pipe.c
index b2075ecd4751..6da11ea9da49 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -518,14 +518,9 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
/* Insert it into the buffer array */
buf = &pipe->bufs[head & mask];
- buf->page = page;
- buf->ops = &anon_pipe_buf_ops;
- buf->offset = 0;
- buf->len = 0;
- if (is_packetized(filp))
- buf->flags = PIPE_BUF_FLAG_PACKET;
- else
- buf->flags = PIPE_BUF_FLAG_CAN_MERGE;
+ pipe_buf_init(buf, page, 0, 0,
+ &anon_pipe_buf_ops,
+ is_packetized(filp) ? PIPE_BUF_FLAG_PACKET : PIPE_BUF_FLAG_CAN_MERGE);
pipe->tmp_page = NULL;
copied = copy_page_from_iter(page, 0, PAGE_SIZE, from);
diff --git a/fs/splice.c b/fs/splice.c
index 5dbce4dcc1a7..d2e4205acc46 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -200,12 +200,11 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
while (!pipe_full(head, tail, pipe->max_usage)) {
struct pipe_buffer *buf = &pipe->bufs[head & mask];
- buf->page = spd->pages[page_nr];
- buf->offset = spd->partial[page_nr].offset;
- buf->len = spd->partial[page_nr].len;
+ pipe_buf_init(buf, spd->pages[page_nr],
+ spd->partial[page_nr].offset,
+ spd->partial[page_nr].len,
+ spd->ops, 0);
buf->private = spd->partial[page_nr].private;
- buf->ops = spd->ops;
- buf->flags = 0;
head++;
pipe->head = head;
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 0e36a58adf0e..61639682cc4e 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -179,6 +179,26 @@ static inline unsigned int pipe_space_for_user(unsigned int head, unsigned int t
return p_space;
}
+/**
+ * Initialize a struct pipe_buffer.
+ */
+static inline void pipe_buf_init(struct pipe_buffer *buf,
+ struct page *page,
+ unsigned int offset, unsigned int len,
+ const struct pipe_buf_operations *ops,
+ unsigned int flags)
+{
+ buf->page = page;
+ buf->offset = offset;
+ buf->len = len;
+ buf->ops = ops;
+ buf->flags = flags;
+
+ /* not initializing the "private" member because it is only
+ used by pipe_buf_operations which inject it via struct
+ partial_page / struct splice_pipe_desc */
+}
+
/**
* pipe_buf_get - get a reference to a pipe_buffer
* @pipe: the pipe that the buffer belongs to
diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c
index 9c9eb20dd2c5..34720138cc22 100644
--- a/kernel/watch_queue.c
+++ b/kernel/watch_queue.c
@@ -106,12 +106,10 @@ static bool post_one_notification(struct watch_queue *wqueue,
kunmap_atomic(p);
buf = &pipe->bufs[head & mask];
- buf->page = page;
+ pipe_buf_init(buf, page, offset, len,
+ &watch_queue_pipe_buf_ops,
+ PIPE_BUF_FLAG_WHOLE);
buf->private = (unsigned long)wqueue;
- buf->ops = &watch_queue_pipe_buf_ops;
- buf->offset = offset;
- buf->len = len;
- buf->flags = PIPE_BUF_FLAG_WHOLE;
pipe->head = head + 1;
if (!test_and_clear_bit(note, wqueue->notes_bitmap)) {
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 6dd5330f7a99..289e96947fb5 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -413,12 +413,8 @@ static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t by
if (pipe_full(i_head, p_tail, pipe->max_usage))
return 0;
- buf->ops = &page_cache_pipe_buf_ops;
- buf->flags = 0;
get_page(page);
- buf->page = page;
- buf->offset = offset;
- buf->len = bytes;
+ pipe_buf_init(buf, page, offset, bytes, &page_cache_pipe_buf_ops, 0);
pipe->head = i_head + 1;
i->iov_offset = offset + bytes;
@@ -577,11 +573,8 @@ static size_t push_pipe(struct iov_iter *i, size_t size,
if (!page)
break;
- buf->ops = &default_pipe_buf_ops;
- buf->flags = 0;
- buf->page = page;
- buf->offset = 0;
- buf->len = min_t(ssize_t, left, PAGE_SIZE);
+ pipe_buf_init(buf, page, 0, min_t(ssize_t, left, PAGE_SIZE),
+ &default_pipe_buf_ops, 0);
left -= buf->len;
iter_head++;
pipe->head = iter_head;
--
2.34.0
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