[PATCH 04/13] fs: add cdev_umount_all()

[Sascha Hauer <s.hauer@pengutronix.de>]

umount_by_cdev() unmounts the filesystems mounted from one cdev. For a
partitioned device that is not enough: the filesystems are mounted from
the partitions, not from the disk itself, so unmounting the disk leaves
them behind.

Add a variant that walks the partitions as well. This is what a driver
needs when the medium it handed out is gone and the mounts on it have
become useless.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Assisted-by: Claude:claude-opus-5
---
 fs/fs.c      | 31 +++++++++++++++++++++++++++++++
 include/fs.h |  1 +
 2 files changed, 32 insertions(+)

diff --git a/fs/fs.c b/fs/fs.c
index ce41f23f88..f0d3d9fa0a 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -1033,6 +1033,37 @@ int umount_by_cdev(struct cdev *cdev)
 }
 EXPORT_SYMBOL(umount_by_cdev);
 
+/**
+ * cdev_umount_all - unmount everything mounted from a cdev
+ * @cdev: cdev to unmount
+ *
+ * Unmounts the filesystems mounted from @cdev and from its partitions.
+ * Useful for a medium that is gone, where the mounts cannot be used
+ * anymore anyway.
+ *
+ * Return: 0 on success or if nothing was mounted, the first error
+ *         otherwise
+ */
+int cdev_umount_all(struct cdev *cdev)
+{
+	struct cdev *partcdev;
+	int first_error = 0;
+	int ret;
+
+	for_each_cdev_partition(partcdev, cdev) {
+		ret = cdev_umount_all(partcdev);
+		if (ret && !first_error)
+			first_error = ret;
+	}
+
+	ret = umount_by_cdev(cdev);
+	if (ret && !first_error)
+		first_error = ret;
+
+	return first_error;
+}
+EXPORT_SYMBOL(cdev_umount_all);
+
 struct readdir_entry {
 	struct dirent d;
 	struct list_head list;
diff --git a/include/fs.h b/include/fs.h
index 9c3c8d9512..0cc58d73c2 100644
--- a/include/fs.h
+++ b/include/fs.h
@@ -112,6 +112,7 @@ static inline bool is_tftp_fs(const char *path)
 
 int flush(int fd);
 int umount_by_cdev(struct cdev *cdev);
+int cdev_umount_all(struct cdev *cdev);
 
 /* not-so-standard functions */
 #define ERASE_SIZE_ALL	((loff_t) - 1)

-- 
2.47.3