[PATCH v2 1/2] pipe: introduce struct file_operations pipeanon_fops

Oleg Nesterov
2025-02-05T15:34:08Z

So that fifos and anonymous pipes could have different f_op methods.
Preparation to simplify the next patch.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
fs/internal.h | 1 +
fs/pipe.c | 23 ++++++++++++++++++-----
2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/fs/internal.h b/fs/internal.h
index e7f02ae1e098..dfdc2b2cf2f5 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -229,6 +229,7 @@ extern void d_genocide(struct dentry *);
* pipe.c
*/
extern const struct file_operations pipefifo_fops;
+extern const struct file_operations pipeanon_fops;

/*
* fs_pin.c
diff --git a/fs/pipe.c b/fs/pipe.c
index 94b59045ab44..b05cded28d9b 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -895,7 +895,7 @@ static struct inode * get_pipe_inode(void)
inode->i_pipe = pipe;
pipe->files = 2;
pipe->readers = pipe->writers = 1;
- inode->i_fop = &pipefifo_fops;
+ inode->i_fop = &pipeanon_fops;

/*
* Mark the inode dirty from the very beginning,
@@ -938,7 +938,7 @@ int create_pipe_files(struct file **res, int flags)

f = alloc_file_pseudo(inode, pipe_mnt, "",
O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT)),
- &pipefifo_fops);
+ &pipeanon_fops);
if (IS_ERR(f)) {
free_pipe_info(inode->i_pipe);
iput(inode);
@@ -949,7 +949,7 @@ int create_pipe_files(struct file **res, int flags)
f->f_pipe = 0;

res[0] = alloc_file_clone(f, O_RDONLY | (flags & O_NONBLOCK),
- &pipefifo_fops);
+ &pipeanon_fops);
if (IS_ERR(res[0])) {
put_pipe_info(inode, inode->i_pipe);
fput(f);
@@ -1107,8 +1107,8 @@ static void wake_up_partner(struct pipe_inode_info *pipe)

static int fifo_open(struct inode *inode, struct file *filp)
{
+ bool is_pipe = inode->i_fop == &pipeanon_fops;
struct pipe_inode_info *pipe;
- bool is_pipe = inode->i_sb->s_magic == PIPEFS_MAGIC;
int ret;

filp->f_pipe = 0;
@@ -1241,6 +1241,17 @@ const struct file_operations pipefifo_fops = {
.splice_write = iter_file_splice_write,
};

+const struct file_operations pipeanon_fops = {
+ .open = fifo_open,
+ .read_iter = pipe_read,
+ .write_iter = pipe_write,
+ .poll = pipe_poll,
+ .unlocked_ioctl = pipe_ioctl,
+ .release = pipe_release,
+ .fasync = pipe_fasync,
+ .splice_write = iter_file_splice_write,
+};
+
/*
* Currently we rely on the pipe array holding a power-of-2 number
* of pages. Returns 0 on error.
@@ -1388,7 +1399,9 @@ struct pipe_inode_info *get_pipe_info(struct file *file, bool for_splice)
{
struct pipe_inode_info *pipe = file->private_data;

- if (file->f_op != &pipefifo_fops || !pipe)
+ if (!pipe)
+ return NULL;
+ if (file->f_op != &pipefifo_fops && file->f_op != &pipeanon_fops)
return NULL;
if (for_splice && pipe_has_watch_queue(pipe))
return NULL;
--
2.25.1.362.g51ebf55