btrfs: add helpers for FS_XFLAG_* conversion

Preparatory work for the FS_IOC_FSGETXATTR ioctl, basic conversions and
checking helpers.

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 47c1b96..054fa20 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -338,6 +338,38 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
        return ret;
 }
 
+/*
+ * Translate btrfs internal inode flags to xflags as expected by the
+ * FS_IOC_FSGETXATT ioctl. Filter only the supported ones, unknown flags are
+ * silently dropped.
+ */
+static unsigned int btrfs_inode_flags_to_xflags(unsigned int flags)
+{
+       unsigned int xflags = 0;
+
+       if (flags & BTRFS_INODE_APPEND)
+               xflags |= FS_XFLAG_APPEND;
+       if (flags & BTRFS_INODE_IMMUTABLE)
+               xflags |= FS_XFLAG_IMMUTABLE;
+       if (flags & BTRFS_INODE_NOATIME)
+               xflags |= FS_XFLAG_NOATIME;
+       if (flags & BTRFS_INODE_NODUMP)
+               xflags |= FS_XFLAG_NODUMP;
+       if (flags & BTRFS_INODE_SYNC)
+               xflags |= FS_XFLAG_SYNC;
+
+       return xflags;
+}
+
+/* Check if @flags are a supported and valid set of FS_XFLAGS_* flags */
+static int check_xflags(unsigned int flags)
+{
+       if (flags & ~(FS_XFLAG_APPEND | FS_XFLAG_IMMUTABLE | FS_XFLAG_NOATIME |
+                     FS_XFLAG_NODUMP | FS_XFLAG_SYNC))
+               return -EOPNOTSUPP;
+       return 0;
+}
+
 static int btrfs_ioctl_getversion(struct file *file, int __user *arg)
 {
        struct inode *inode = file_inode(file);