linux-kernel - [PATCH 2/4] fs/pipe: move check to pipe_has_watch

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Message-Id: <20230921075755.1378787-2-max.kellermann@ionos.com>
Date:   Thu, 21 Sep 2023 09:57:53 +0200
From:   Max Kellermann <max.kellermann@...os.com>
To:     viro@...iv.linux.org.uk, brauner@...nel.org, howells@...hat.com
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Max Kellermann <max.kellermann@...os.com>
Subject: [PATCH 2/4] fs/pipe: move check to pipe_has_watch_queue()

This declutters the code by reducing the number of #ifdefs and makes
the watch_queue checks simpler.  This has no runtime effect; the
machine code is identical.

Signed-off-by: Max Kellermann <max.kellermann@...os.com>
---
 fs/pipe.c                 | 12 +++---------
 include/linux/pipe_fs_i.h | 13 +++++++++++++
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/fs/pipe.c b/fs/pipe.c
index 6c1a9b1db907..6ecaccb48738 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -437,12 +437,10 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
 		goto out;
 	}
 
-#ifdef CONFIG_WATCH_QUEUE
-	if (pipe->watch_queue) {
+	if (pipe_has_watch_queue(pipe)) {
 		ret = -EXDEV;
 		goto out;
 	}
-#endif
 
 	/*
 	 * If it wasn't empty we try to merge new data into
@@ -1325,10 +1323,8 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned int arg)
 	unsigned int nr_slots, size;
 	long ret = 0;
 
-#ifdef CONFIG_WATCH_QUEUE
-	if (pipe->watch_queue)
+	if (pipe_has_watch_queue(pipe))
 		return -EBUSY;
-#endif
 
 	size = round_pipe_size(arg);
 	nr_slots = size >> PAGE_SHIFT;
@@ -1380,10 +1376,8 @@ struct pipe_inode_info *get_pipe_info(struct file *file, bool for_splice)
 
 	if (file->f_op != &pipefifo_fops || !pipe)
 		return NULL;
-#ifdef CONFIG_WATCH_QUEUE
-	if (for_splice && pipe->watch_queue)
+	if (for_splice && pipe_has_watch_queue(pipe))
 		return NULL;
-#endif
 	return pipe;
 }
 
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 598a411d7da2..699507c52b72 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -124,6 +124,19 @@ struct pipe_buf_operations {
 	bool (*get)(struct pipe_inode_info *, struct pipe_buffer *);
 };
 
+/**
+ * pipe_has_watch_queue - Check whether the pipe is a watch_queue,
+ * i.e. it was created with O_NOTIFICATION_PIPE
+ */
+static inline bool pipe_has_watch_queue(const struct pipe_inode_info *pipe)
+{
+#ifdef CONFIG_WATCH_QUEUE
+	return pipe->watch_queue != NULL;
+#else
+	return false;
+#endif
+}
+
 /**
  * pipe_empty - Return true if the pipe is empty
  * @head: The pipe ring head pointer
-- 
2.39.2