Allow a filesystem to indicate that it supports encoding autonomous file
handles that can be decoded without having to pass a filesystem for the
filesystem. In other words, the file handle uniquely identifies the
filesystem.
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
---
fs/fhandle.c | 7 ++++++-
include/linux/exportfs.h | 4 +++-
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/fs/fhandle.c b/fs/fhandle.c
index 22edced83e4c..ab4891925b52 100644
--- a/fs/fhandle.c
+++ b/fs/fhandle.c
@@ -23,12 +23,13 @@ static long do_sys_name_to_handle(const struct path *path,
struct file_handle f_handle;
int handle_dwords, handle_bytes;
struct file_handle *handle = NULL;
+ const struct export_operations *eops = path->dentry->d_sb->s_export_op;
/*
* We need to make sure whether the file system support decoding of
* the file handle if decodeable file handle was requested.
*/
- if (!exportfs_can_encode_fh(path->dentry->d_sb->s_export_op, fh_flags))
+ if (!exportfs_can_encode_fh(eops, fh_flags))
return -EOPNOTSUPP;
/*
@@ -90,6 +91,10 @@ static long do_sys_name_to_handle(const struct path *path,
if (d_is_dir(path->dentry))
handle->handle_type |= FILEID_IS_DIR;
}
+
+ /* Filesystems supports autonomous file handles. */
+ if (eops->flags & EXPORT_OP_AUTONOMOUS_HANDLES)
+ handle->handle_type |= FILEID_IS_AUTONOMOUS;
retval = 0;
}
/* copy the mount id */
diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h
index 5bb757b51f5c..f7f9038b285e 100644
--- a/include/linux/exportfs.h
+++ b/include/linux/exportfs.h
@@ -188,7 +188,8 @@ struct handle_to_path_ctx {
/* Flags supported in encoded handle_type that is exported to user */
#define FILEID_IS_CONNECTABLE 0x10000
#define FILEID_IS_DIR 0x20000
-#define FILEID_VALID_USER_FLAGS (FILEID_IS_CONNECTABLE | FILEID_IS_DIR)
+#define FILEID_IS_AUTONOMOUS 0x40000
+#define FILEID_VALID_USER_FLAGS (FILEID_IS_CONNECTABLE | FILEID_IS_DIR | FILEID_IS_AUTONOMOUS)
/**
* struct export_operations - for nfsd to communicate with file systems
@@ -285,6 +286,7 @@ struct export_operations {
*/
#define EXPORT_OP_FLUSH_ON_CLOSE (0x20) /* fs flushes file data on close */
#define EXPORT_OP_NOLOCKS (0x40) /* no file locking support */
+#define EXPORT_OP_AUTONOMOUS_HANDLES (0x80) /* filesystem supports autonomous file handles */
unsigned long flags;
};
--
2.47.2
