pipe: introduce struct file_operations pipeanon_fops

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>
Link: https://lore.kernel.org/r/20250205181747.GB13817@redhat.com
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/pipe.c b/fs/pipe.c
index 94b59045ab44bced0e8a1e0179df0e90fe9df658..2eacfde61e745f0dcbe77ff768f906dd3aeb3771 100644 (file)
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -878,6 +878,8 @@ static const struct dentry_operations pipefs_dentry_operations = {
        .d_dname        = pipefs_dname,
 };
 
+static const struct file_operations pipeanon_fops;
+
 static struct inode * get_pipe_inode(void)
 {
        struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb);
@@ -895,7 +897,7 @@ 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 +940,7 @@ 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 +951,7 @@ 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 +1109,8 @@ 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 +1243,17 @@ const struct file_operations pipefifo_fops = {
        .splice_write   = iter_file_splice_write,
 };
 
+static 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 +1401,9 @@ 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;