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Commit 0002b271 authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] md: limit size of sb read/written to appropriate amount 



version-1 superblocks are not (normally) 4K long, and can be of variable size.
 Writing the full 4K can cause corruption (but only in non-default
configurations).

With this patch the super-block-flavour can choose a size to read, and set a
size to write based on what it finds.

Signed-off-by: default avatarNeil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 773f7834

drivers/md/md.c

+15 −5
Original line number Diff line number Diff line
@@ -393,7 +393,7 @@ int sync_page_io(struct block_device *bdev, sector_t sector, int size, 
	return ret;

}



static int read_disk_sb(mdk_rdev_t * rdev)

static int read_disk_sb(mdk_rdev_t * rdev, int size)

{

	char b[BDEVNAME_SIZE];

	if (!rdev->sb_page) {
@@ -404,7 +404,7 @@ static int read_disk_sb(mdk_rdev_t * rdev) 
		return 0;





	if (!sync_page_io(rdev->bdev, rdev->sb_offset<<1, MD_SB_BYTES, rdev->sb_page, READ))

	if (!sync_page_io(rdev->bdev, rdev->sb_offset<<1, size, rdev->sb_page, READ))

		goto fail;

	rdev->sb_loaded = 1;

	return 0;
@@ -531,7 +531,7 @@ static int super_90_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version 
	sb_offset = calc_dev_sboffset(rdev->bdev);

	rdev->sb_offset = sb_offset;



	ret = read_disk_sb(rdev);

	ret = read_disk_sb(rdev, MD_SB_BYTES);

	if (ret) return ret;



	ret = -EINVAL;
@@ -564,6 +564,7 @@ static int super_90_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version 


	rdev->preferred_minor = sb->md_minor;

	rdev->data_offset = 0;

	rdev->sb_size = MD_SB_BYTES;



	if (sb->level == LEVEL_MULTIPATH)

		rdev->desc_nr = -1;
@@ -837,6 +838,7 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version) 
	int ret;

	sector_t sb_offset;

	char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];

	int bmask;



	/*

	 * Calculate the position of the superblock.
@@ -865,7 +867,10 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version) 
	}

	rdev->sb_offset = sb_offset;



	ret = read_disk_sb(rdev);

	/* superblock is rarely larger than 1K, but it can be larger,

	 * and it is safe to read 4k, so we do that

	 */

	ret = read_disk_sb(rdev, 4096);

	if (ret) return ret;
@@ -891,6 +896,11 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version) 
	rdev->preferred_minor = 0xffff;

	rdev->data_offset = le64_to_cpu(sb->data_offset);



	rdev->sb_size = le32_to_cpu(sb->max_dev) * 2 + 256;

	bmask = block_size(rdev->bdev)-1;

	if (rdev->sb_size & bmask)

		rdev-> sb_size = (rdev->sb_size | bmask)+1;



	if (refdev == 0)

		return 1;

	else {
@@ -1375,7 +1385,7 @@ static void md_update_sb(mddev_t * mddev) 
		dprintk("%s ", bdevname(rdev->bdev,b));

		if (!rdev->faulty) {

			md_super_write(mddev,rdev,

				       rdev->sb_offset<<1, MD_SB_BYTES,

				       rdev->sb_offset<<1, rdev->sb_size,

				       rdev->sb_page);

			dprintk(KERN_INFO "(write) %s's sb offset: %llu\n",

				bdevname(rdev->bdev,b),

include/linux/raid/md_k.h

+1 −0
Original line number Diff line number Diff line
@@ -102,6 +102,7 @@ struct mdk_rdev_s 
	int		sb_loaded;

	sector_t	data_offset;	/* start of data in array */

	sector_t	sb_offset;

	int		sb_size;	/* bytes in the superblock */

	int		preferred_minor;	/* autorun support */



	/* A device can be in one of three states based on two flags: