This commit add fuse connection device id to
fdinfo of opened fuse files.

Related discussions can be found at links below.

Link: https://lore.kernel.org/all/CAOQ4uxgS3OUy9tpphAJKCQFRAn2zTERXXa0QN_KvP6ZOe2KVBw@mail.gmail.com/
Link: https://lore.kernel.org/all/CAOQ4uxgkg0uOuAWO2wOPNkMmD9wqd5wMX+gTfCT-zVHBC8CkZg@mail.gmail.com/
Link: https://lore.kernel.org/all/CAC1kPDOdDdPQVKs0C-LmgT1_MGBWbFqy4F+5TeunYBkA=xq7+Q@mail.gmail.com/
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Chen Linxuan <chenlinxuan@uniontech.com>
---
 fs/fuse/file.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 754378dd9f715..a34fec685d3db 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -3392,6 +3392,14 @@ static ssize_t fuse_copy_file_range(struct file *src_file, loff_t src_off,
 	return ret;
 }
 
+static void fuse_file_show_fdinfo(struct seq_file *seq, struct file *f)
+{
+	struct fuse_file *ff = f->private_data;
+	struct fuse_conn *fc = ff->fm->fc;
+
+	seq_printf(seq, "fuse conn:%u\n", fc->dev);
+}
+
 static const struct file_operations fuse_file_operations = {
 	.llseek		= fuse_file_llseek,
 	.read_iter	= fuse_file_read_iter,
@@ -3411,6 +3419,9 @@ static const struct file_operations fuse_file_operations = {
 	.poll		= fuse_file_poll,
 	.fallocate	= fuse_file_fallocate,
 	.copy_file_range = fuse_copy_file_range,
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo	= fuse_file_show_fdinfo,
+#endif
 };
 
 static const struct address_space_operations fuse_file_aops  = {
-- 
2.43.0

On Sun, 11 May 2025 at 10:50, Chen Linxuan <chenlinxuan@uniontech.com> wrote:
>
> This commit add fuse connection device id to
> fdinfo of opened fuse files.

What I meant is adding this to fuse_dev_operations.

Thanks,
Miklos

On Mon, May 12, 2025 at 2:55 PM Miklos Szeredi <miklos@szeredi.hu> wrote:

> What I meant is adding this to fuse_dev_operations.

But it doesn't seem like exposing this information here would be a bad
idea either, does it?
For example, if a system administrator wants to write a script to
abort the FUSE connection
corresponding to a specific directory,
the script could use this information to locate the relevant connection.

Thanks,
Chen Linxuan

On Thu, May 15, 2025 at 2:36 PM Chen Linxuan <chenlinxuan@uniontech.com> wrote:

> But it doesn't seem like exposing this information here would be a bad
> idea either, does it?
> For example, if a system administrator wants to write a script to
> abort the FUSE connection
> corresponding to a specific directory,
> the script could use this information to locate the relevant connection.

Oh I see I can get connection id via .st_dev from stat(2)