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

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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: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2009-12-14 12:49:54 +11:00
parent 9cd30fdc33
commit f6af949c56
2 changed files with 15 additions and 5 deletions
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14
drivers/md/bitmap.c
View file

@ -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))

6
drivers/md/md.h
View file

@ -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.
*/