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Commit f6af949c authored by NeilBrown's avatar NeilBrown
Browse files

md: support bitmap offset appropriate for external-metadata arrays. 



For md arrays were metadata is managed externally, the kernel does not
know about a superblock so the superblock offset is 0.
If we want to have a write-intent-bitmap near the end of the
devices of such an array, we should support sector_t sized offset.
We need offset be possibly negative for when the bitmap is before
the metadata, so use loff_t instead.

Also add sanity check that bitmap does not overlap with data.

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 9cd30fdc

drivers/md/bitmap.c

+11 −3
Original line number Diff line number Diff line
@@ -212,7 +212,7 @@ static void bitmap_checkfree(struct bitmap *bitmap, unsigned long page) 
 */



/* IO operations when bitmap is stored near all superblocks */

static struct page *read_sb_page(mddev_t *mddev, long offset,

static struct page *read_sb_page(mddev_t *mddev, loff_t offset,

				 struct page *page,

				 unsigned long index, int size)

{
@@ -287,14 +287,22 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait) 


	while ((rdev = next_active_rdev(rdev, mddev)) != NULL) {

			int size = PAGE_SIZE;

			long offset = mddev->bitmap_info.offset;

			loff_t offset = mddev->bitmap_info.offset;

			if (page->index == bitmap->file_pages-1)

				size = roundup(bitmap->last_page_size,

					       bdev_logical_block_size(rdev->bdev));

			/* Just make sure we aren't corrupting data or

			 * metadata

			 */

			if (offset < 0) {

			if (mddev->external) {

				/* Bitmap could be anywhere. */

				if (rdev->sb_start + offset + (page->index *(PAGE_SIZE/512)) >

				    rdev->data_offset &&

				    rdev->sb_start + offset < 

				    rdev->data_offset + mddev->dev_sectors +

				    (PAGE_SIZE/512))

					goto bad_alignment;

			} else if (offset < 0) {

				/* DATA  BITMAP METADATA  */

				if (offset

				    + (long)(page->index * (PAGE_SIZE/512))

drivers/md/md.h

+4 −2
Original line number Diff line number Diff line
@@ -282,11 +282,13 @@ struct mddev_s 
	struct bitmap                   *bitmap; /* the bitmap for the device */

	struct {

		struct file		*file; /* the bitmap file */

		long			offset; /* offset from superblock of

		loff_t			offset; /* offset from superblock of

						 * start of bitmap. May be

						 * negative, but not '0'

						 * For external metadata, offset

						 * from start of device. 

						 */

		long			default_offset; /* this is the offset to use when

		loff_t			default_offset; /* this is the offset to use when

							 * hot-adding a bitmap.  It should

							 * eventually be settable by sysfs.

							 */