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Commit bd926c63 authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] md: make md on-disk bitmaps not host-endian 



Current bitmaps use set_bit et.al and so are host-endian, which means
not-portable.  Oops.

Define a new version number (4) for which bitmaps are little-endian.

Signed-off-by: default avatarNeil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent b2d444d7

drivers/md/bitmap.c

+18 −4
Original line number Diff line number Diff line
@@ -482,7 +482,8 @@ static int bitmap_read_sb(struct bitmap *bitmap) 
	/* verify that the bitmap-specific fields are valid */

	if (sb->magic != cpu_to_le32(BITMAP_MAGIC))

		reason = "bad magic";

	else if (sb->version != cpu_to_le32(BITMAP_MAJOR))

	else if (le32_to_cpu(sb->version) < BITMAP_MAJOR_LO ||

		 le32_to_cpu(sb->version) > BITMAP_MAJOR_HI)

		reason = "unrecognized superblock version";

	else if (chunksize < 512 || chunksize > (1024 * 1024 * 4))

		reason = "bitmap chunksize out of range (512B - 4MB)";
@@ -527,6 +528,8 @@ success: 
	bitmap->daemon_lastrun = jiffies;

	bitmap->max_write_behind = write_behind;

	bitmap->flags |= sb->state;

	if (le32_to_cpu(sb->version) == BITMAP_MAJOR_HOSTENDIAN)

		bitmap->flags |= BITMAP_HOSTENDIAN;

	bitmap->events_cleared = le64_to_cpu(sb->events_cleared);

	if (sb->state & BITMAP_STALE)

		bitmap->events_cleared = bitmap->mddev->events;
@@ -764,7 +767,10 @@ static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block) 


 	/* set the bit */

	kaddr = kmap_atomic(page, KM_USER0);

	if (bitmap->flags & BITMAP_HOSTENDIAN)

		set_bit(bit, kaddr);

	else

		ext2_set_bit(bit, kaddr);

	kunmap_atomic(kaddr, KM_USER0);

	PRINTK("set file bit %lu page %lu\n", bit, page->index);
@@ -891,6 +897,7 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start) 
	oldindex = ~0L;



	for (i = 0; i < chunks; i++) {

		int b;

		index = file_page_index(i);

		bit = file_page_offset(i);

		if (index != oldindex) { /* this is a new page, read it in */
@@ -939,7 +946,11 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start) 


			bitmap->filemap[bitmap->file_pages++] = page;

		}

		if (test_bit(bit, page_address(page))) {

		if (bitmap->flags & BITMAP_HOSTENDIAN)

			b = test_bit(bit, page_address(page));

		else

			b = ext2_test_bit(bit, page_address(page));

		if (b) {

			/* if the disk bit is set, set the memory bit */

			bitmap_set_memory_bits(bitmap, i << CHUNK_BLOCK_SHIFT(bitmap),

					       ((i+1) << (CHUNK_BLOCK_SHIFT(bitmap)) >= start)
@@ -1097,7 +1108,10 @@ int bitmap_daemon_work(struct bitmap *bitmap) 
						  -1);



				/* clear the bit */

				if (bitmap->flags & BITMAP_HOSTENDIAN)

					clear_bit(file_page_offset(j), page_address(page));

				else

					ext2_clear_bit(file_page_offset(j), page_address(page));

			}

		}

		spin_unlock_irqrestore(&bitmap->lock, flags);

drivers/md/md.c

+1 −1
Original line number Diff line number Diff line
@@ -4281,7 +4281,7 @@ static int __init md_init(void) 
			" MD_SB_DISKS=%d\n",

			MD_MAJOR_VERSION, MD_MINOR_VERSION,

			MD_PATCHLEVEL_VERSION, MAX_MD_DEVS, MD_SB_DISKS);

	printk(KERN_INFO "md: bitmap version %d.%d\n", BITMAP_MAJOR,

	printk(KERN_INFO "md: bitmap version %d.%d\n", BITMAP_MAJOR_HI,

			BITMAP_MINOR);



	if (register_blkdev(MAJOR_NR, "md"))

include/linux/raid/bitmap.h

+9 −2
Original line number Diff line number Diff line
@@ -6,7 +6,13 @@ 
#ifndef BITMAP_H

#define BITMAP_H 1



#define BITMAP_MAJOR 3

#define BITMAP_MAJOR_LO 3

/* version 4 insists the bitmap is in little-endian order

 * with version 3, it is host-endian which is non-portable

 */

#define BITMAP_MAJOR_HI 4

#define	BITMAP_MAJOR_HOSTENDIAN 3



#define BITMAP_MINOR 39



/*
@@ -133,7 +139,8 @@ typedef __u16 bitmap_counter_t; 
/* use these for bitmap->flags and bitmap->sb->state bit-fields */

enum bitmap_state {

	BITMAP_ACTIVE = 0x001, /* the bitmap is in use */

	BITMAP_STALE  = 0x002  /* the bitmap file is out of date or had -EIO */

	BITMAP_STALE  = 0x002,  /* the bitmap file is out of date or had -EIO */

	BITMAP_HOSTENDIAN = 0x8000,

};



/* the superblock at the front of the bitmap file -- little endian */

include/linux/raid/md.h

+3 −1
Original line number Diff line number Diff line
@@ -66,8 +66,10 @@ 
 *     and major_version/minor_version accordingly

 * >=2 means that Internal bitmaps are supported by setting MD_SB_BITMAP_PRESENT

 *     in the super status byte

 * >=3 means that bitmap superblock version 4 is supported, which uses

 *     little-ending representation rather than host-endian

 */

#define MD_PATCHLEVEL_VERSION           2

#define MD_PATCHLEVEL_VERSION           3



extern int register_md_personality (int p_num, mdk_personality_t *p);

extern int unregister_md_personality (int p_num);