[PATCH v5 05/42] fs: add attr_flags_to_mnt_flags helper

Christian Brauner
2021-01-12T22:03:45Z

Add a simple helper to translate uapi MOUNT_ATTR_* flags to MNT_* flags
which we will use in follow-up patches too.

Suggested-by: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v2 */
patch not present

/* v3 */
patch not present

/* v4 */
patch introduced

/* v5 */
base-commit: 7c53f6b671f4aba70ff15e1b05148b10d58c2837

- Christoph Hellwig <hch@lst.de>:
- Align "\" in defines further in.
---
fs/namespace.c | 40 ++++++++++++++++++++++++----------------
1 file changed, 24 insertions(+), 16 deletions(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 4aab396e5f21..a1cfcab217e1 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3453,6 +3453,28 @@ SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
return ret;
}

+#define FSMOUNT_VALID_FLAGS \
+ (MOUNT_ATTR_RDONLY | MOUNT_ATTR_NOSUID | MOUNT_ATTR_NODEV | \
+ MOUNT_ATTR_NOEXEC | MOUNT_ATTR__ATIME | MOUNT_ATTR_NODIRATIME)
+
+static unsigned int attr_flags_to_mnt_flags(u64 attr_flags)
+{
+ unsigned int mnt_flags = 0;
+
+ if (attr_flags & MOUNT_ATTR_RDONLY)
+ mnt_flags |= MNT_READONLY;
+ if (attr_flags & MOUNT_ATTR_NOSUID)
+ mnt_flags |= MNT_NOSUID;
+ if (attr_flags & MOUNT_ATTR_NODEV)
+ mnt_flags |= MNT_NODEV;
+ if (attr_flags & MOUNT_ATTR_NOEXEC)
+ mnt_flags |= MNT_NOEXEC;
+ if (attr_flags & MOUNT_ATTR_NODIRATIME)
+ mnt_flags |= MNT_NODIRATIME;
+
+ return mnt_flags;
+}
+
/*
* Create a kernel mount representation for a new, prepared superblock
* (specified by fs_fd) and attach to an open_tree-like file descriptor.
@@ -3475,24 +3497,10 @@ SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags,
if ((flags & ~(FSMOUNT_CLOEXEC)) != 0)
return -EINVAL;

- if (attr_flags & ~(MOUNT_ATTR_RDONLY |
- MOUNT_ATTR_NOSUID |
- MOUNT_ATTR_NODEV |
- MOUNT_ATTR_NOEXEC |
- MOUNT_ATTR__ATIME |
- MOUNT_ATTR_NODIRATIME))
+ if (attr_flags & ~FSMOUNT_VALID_FLAGS)
return -EINVAL;

- if (attr_flags & MOUNT_ATTR_RDONLY)
- mnt_flags |= MNT_READONLY;
- if (attr_flags & MOUNT_ATTR_NOSUID)
- mnt_flags |= MNT_NOSUID;
- if (attr_flags & MOUNT_ATTR_NODEV)
- mnt_flags |= MNT_NODEV;
- if (attr_flags & MOUNT_ATTR_NOEXEC)
- mnt_flags |= MNT_NOEXEC;
- if (attr_flags & MOUNT_ATTR_NODIRATIME)
- mnt_flags |= MNT_NODIRATIME;
+ mnt_flags = attr_flags_to_mnt_flags(attr_flags);

switch (attr_flags & MOUNT_ATTR__ATIME) {
case MOUNT_ATTR_STRICTATIME:
--
2.30.0