vfs: create a generic checking and prep function for FS_IOC_SETFLAGS

Create a generic function to check incoming FS_IOC_SETFLAGS flag values
and later prepare the inode for updates so that we can standardize the
implementations that follow ext4's flag values.

Note that the efivarfs implementation no longer fails a no-op SETFLAGS
without CAP_LINUX_IMMUTABLE since that's the behavior in ext*.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: David Sterba <dsterba@suse.com>
Reviewed-by: Bob Peterson <rpeterso@redhat.com>

fs/gfs2/file.c

@@ -136,27 +136,36 @@ static struct {
 	{FS_JOURNAL_DATA_FL, GFS2_DIF_JDATA | GFS2_DIF_INHERIT_JDATA},
 };
 
+static inline u32 gfs2_gfsflags_to_fsflags(struct inode *inode, u32 gfsflags)
+{
+	int i;
+	u32 fsflags = 0;
+
+	if (S_ISDIR(inode->i_mode))
+		gfsflags &= ~GFS2_DIF_JDATA;
+	else
+		gfsflags &= ~GFS2_DIF_INHERIT_JDATA;
+
+	for (i = 0; i < ARRAY_SIZE(fsflag_gfs2flag); i++)
+		if (gfsflags & fsflag_gfs2flag[i].gfsflag)
+			fsflags |= fsflag_gfs2flag[i].fsflag;
+	return fsflags;
+}
+
 static int gfs2_get_flags(struct file *filp, u32 __user *ptr)
 {
 	struct inode *inode = file_inode(filp);
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_holder gh;
-	int i, error;
-	u32 gfsflags, fsflags = 0;
+	int error;
+	u32 fsflags;
 
 	gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 	error = gfs2_glock_nq(&gh);
 	if (error)
 		goto out_uninit;
 
-	gfsflags = ip->i_diskflags;
-	if (S_ISDIR(inode->i_mode))
-		gfsflags &= ~GFS2_DIF_JDATA;
-	else
-		gfsflags &= ~GFS2_DIF_INHERIT_JDATA;
-	for (i = 0; i < ARRAY_SIZE(fsflag_gfs2flag); i++)
-		if (gfsflags & fsflag_gfs2flag[i].gfsflag)
-			fsflags |= fsflag_gfs2flag[i].fsflag;
+	fsflags = gfs2_gfsflags_to_fsflags(inode, ip->i_diskflags);
 
 	if (put_user(fsflags, ptr))
 		error = -EFAULT;
@@ -200,9 +209,11 @@ void gfs2_set_inode_flags(struct inode *inode)
  * @filp: file pointer
  * @reqflags: The flags to set
  * @mask: Indicates which flags are valid
+ * @fsflags: The FS_* inode flags passed in
  *
  */
-static int do_gfs2_set_flags(struct file *filp, u32 reqflags, u32 mask)
+static int do_gfs2_set_flags(struct file *filp, u32 reqflags, u32 mask,
+			     const u32 fsflags)
 {
 	struct inode *inode = file_inode(filp);
 	struct gfs2_inode *ip = GFS2_I(inode);
@@ -210,7 +221,7 @@ static int do_gfs2_set_flags(struct file *filp, u32 reqflags, u32 mask)
 	struct buffer_head *bh;
 	struct gfs2_holder gh;
 	int error;
-	u32 new_flags, flags;
+	u32 new_flags, flags, oldflags;
 
 	error = mnt_want_write_file(filp);
 	if (error)
@@ -220,6 +231,11 @@ static int do_gfs2_set_flags(struct file *filp, u32 reqflags, u32 mask)
 	if (error)
 		goto out_drop_write;
 
+	oldflags = gfs2_gfsflags_to_fsflags(inode, ip->i_diskflags);
+	error = vfs_ioc_setflags_prepare(inode, oldflags, fsflags);
+	if (error)
+		goto out;
+
 	error = -EACCES;
 	if (!inode_owner_or_capable(inode))
 		goto out;
@@ -308,7 +324,7 @@ static int gfs2_set_flags(struct file *filp, u32 __user *ptr)
 		mask &= ~(GFS2_DIF_TOPDIR | GFS2_DIF_INHERIT_JDATA);
 	}
 
-	return do_gfs2_set_flags(filp, gfsflags, mask);
+	return do_gfs2_set_flags(filp, gfsflags, mask, fsflags);
 }
 
 static int gfs2_getlabel(struct file *filp, char __user *label)