md/bitmap: move some fields of 'struct bitmap' into a 'storage' substruct.

This new 'struct bitmap_storage' reflects the external storage of the
bitmap.
Having this clearly defined will make it easier to change the storage
used while the array is active.
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/bitmap.h

@@ -188,12 +188,17 @@ struct bitmap {
 	/* bitmap spinlock */
 	spinlock_t lock;
 
-	struct file *file; /* backing disk file */
-	struct page *sb_page; /* cached copy of the bitmap file superblock */
-	struct page **filemap; /* list of cache pages for the file */
-	unsigned long *filemap_attr; /* attributes associated w/ filemap pages */
-	unsigned long file_pages; /* number of pages in the file */
-	int last_page_size; /* bytes in the last page */
+	struct bitmap_storage {
+		struct file *file;		/* backing disk file */
+		struct page *sb_page;		/* cached copy of the bitmap
+						 * file superblock */
+		struct page **filemap;		/* list of cache pages for
+						 * the file */
+		unsigned long *filemap_attr;	/* attributes associated
+						 * w/ filemap pages */
+		unsigned long file_pages;	/* number of pages in the file*/
+		int last_page_size;		/* bytes in the last page */
+	} storage;
 
 	unsigned long flags;
 

drivers/md/md.c

@@ -1989,7 +1989,7 @@ super_1_allow_new_offset(struct md_rdev *rdev,
 	bitmap = rdev->mddev->bitmap;
 	if (bitmap && !rdev->mddev->bitmap_info.file &&
 	    rdev->sb_start + rdev->mddev->bitmap_info.offset +
-	    bitmap->file_pages * (PAGE_SIZE>>9) > new_offset)
+	    bitmap->storage.file_pages * (PAGE_SIZE>>9) > new_offset)
 		return 0;
 	if (rdev->badblocks.sector + rdev->badblocks.size > new_offset)
 		return 0;
@@ -5649,7 +5649,7 @@ static int get_bitmap_file(struct mddev * mddev, void __user * arg)
 		goto out;
 
 	/* bitmap disabled, zero the first byte and copy out */
-	if (!mddev->bitmap || !mddev->bitmap->file) {
+	if (!mddev->bitmap || !mddev->bitmap->storage.file) {
 		file->pathname[0] = '\0';
 		goto copy_out;
 	}
@@ -5658,7 +5658,8 @@ static int get_bitmap_file(struct mddev * mddev, void __user * arg)
 	if (!buf)
 		goto out;
 
-	ptr = d_path(&mddev->bitmap->file->f_path, buf, sizeof(file->pathname));
+	ptr = d_path(&mddev->bitmap->storage.file->f_path,
+		     buf, sizeof(file->pathname));
 	if (IS_ERR(ptr))
 		goto out;
 
@@ -6299,7 +6300,7 @@ static int update_array_info(struct mddev *mddev, mdu_array_info_t *info)
 			/* remove the bitmap */
 			if (!mddev->bitmap)
 				return -ENOENT;
-			if (mddev->bitmap->file)
+			if (mddev->bitmap->storage.file)
 				return -EINVAL;
 			mddev->pers->quiesce(mddev, 1);
 			bitmap_destroy(mddev);