Create a helper do_sys_name_to_handle_at() that takes an additional
argument, lookup_flags, beyond the syscall arguments.
Because name_to_handle_at(2) doesn't take any lookup flags, it always
passes 0 for this argument.
Future callers like io_uring may pass LOOKUP_CACHED in order to request
a non-blocking lookup.
This helper's name is confusingly similar to do_sys_name_to_handle()
which takes care of returning the file handle, once the filename has
been turned into a struct path. To distinguish the names more clearly,
rename the latter to do_path_to_handle().
Signed-off-by: Thomas Bertschinger <tahbertschinger@xxxxxxxxx>
---
fs/fhandle.c | 61 ++++++++++++++++++++++++++++-----------------------
fs/internal.h | 9 ++++++++
2 files changed, 43 insertions(+), 27 deletions(-)
diff --git a/fs/fhandle.c b/fs/fhandle.c
index 68a7d2861c58..605ad8e7d93d 100644
--- a/fs/fhandle.c
+++ b/fs/fhandle.c
@@ -14,10 +14,10 @@
#include "internal.h"
#include "mount.h"
-static long do_sys_name_to_handle(const struct path *path,
- struct file_handle __user *ufh,
- void __user *mnt_id, bool unique_mntid,
- int fh_flags)
+static long do_path_to_handle(const struct path *path,
+ struct file_handle __user *ufh,
+ void __user *mnt_id, bool unique_mntid,
+ int fh_flags)
{
long retval;
struct file_handle f_handle;
@@ -111,27 +111,11 @@ static long do_sys_name_to_handle(const struct path *path,
return retval;
}
-/**
- * sys_name_to_handle_at: convert name to handle
- * @dfd: directory relative to which name is interpreted if not absolute
- * @name: name that should be converted to handle.
- * @handle: resulting file handle
- * @mnt_id: mount id of the file system containing the file
- * (u64 if AT_HANDLE_MNT_ID_UNIQUE, otherwise int)
- * @flag: flag value to indicate whether to follow symlink or not
- * and whether a decodable file handle is required.
- *
- * @handle->handle_size indicate the space available to store the
- * variable part of the file handle in bytes. If there is not
- * enough space, the field is updated to return the minimum
- * value required.
- */
-SYSCALL_DEFINE5(name_to_handle_at, int, dfd, const char __user *, name,
- struct file_handle __user *, handle, void __user *, mnt_id,
- int, flag)
+long do_sys_name_to_handle_at(int dfd, const char __user *name,
+ struct file_handle __user *handle,
+ void __user *mnt_id, int flag, int lookup_flags)
{
struct path path;
- int lookup_flags;
int fh_flags = 0;
int err;
@@ -155,19 +139,42 @@ SYSCALL_DEFINE5(name_to_handle_at, int, dfd, const char __user *, name,
else if (flag & AT_HANDLE_CONNECTABLE)
fh_flags |= EXPORT_FH_CONNECTABLE;
- lookup_flags = (flag & AT_SYMLINK_FOLLOW) ? LOOKUP_FOLLOW : 0;
+ if (flag & AT_SYMLINK_FOLLOW)
+ lookup_flags |= LOOKUP_FOLLOW;
if (flag & AT_EMPTY_PATH)
lookup_flags |= LOOKUP_EMPTY;
err = user_path_at(dfd, name, lookup_flags, &path);
if (!err) {
- err = do_sys_name_to_handle(&path, handle, mnt_id,
- flag & AT_HANDLE_MNT_ID_UNIQUE,
- fh_flags);
+ err = do_path_to_handle(&path, handle, mnt_id,
+ flag & AT_HANDLE_MNT_ID_UNIQUE,
+ fh_flags);
path_put(&path);
}
return err;
}
+/**
+ * sys_name_to_handle_at: convert name to handle
+ * @dfd: directory relative to which name is interpreted if not absolute
+ * @name: name that should be converted to handle.
+ * @handle: resulting file handle
+ * @mnt_id: mount id of the file system containing the file
+ * (u64 if AT_HANDLE_MNT_ID_UNIQUE, otherwise int)
+ * @flag: flag value to indicate whether to follow symlink or not
+ * and whether a decodable file handle is required.
+ *
+ * @handle->handle_size indicate the space available to store the
+ * variable part of the file handle in bytes. If there is not
+ * enough space, the field is updated to return the minimum
+ * value required.
+ */
+SYSCALL_DEFINE5(name_to_handle_at, int, dfd, const char __user *, name,
+ struct file_handle __user *, handle, void __user *, mnt_id,
+ int, flag)
+{
+ return do_sys_name_to_handle_at(dfd, name, handle, mnt_id, flag, 0);
+}
+
static int get_path_anchor(int fd, struct path *root)
{
if (fd >= 0) {
diff --git a/fs/internal.h b/fs/internal.h
index 38e8aab27bbd..c972f8ade52d 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -355,3 +355,12 @@ int anon_inode_getattr(struct mnt_idmap *idmap, const struct path *path,
int anon_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
struct iattr *attr);
void pidfs_get_root(struct path *path);
+
+/*
+ * fs/fhandle.c
+ */
+#ifdef CONFIG_FHANDLE
+long do_sys_name_to_handle_at(int dfd, const char __user *name,
+ struct file_handle __user *handle,
+ void __user *mnt_id, int flag, int lookup_flags);
+#endif /* CONFIG_FHANDLE */
--
2.51.0
