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[PATCH] md: make md on-disk bitmaps not host-endian

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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: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
NeilBrown 2005-11-08 21:39:32 -08:00 committed by Linus Torvalds
parent b2d444d7ad
commit bd926c63b7
4 changed files with 31 additions and 8 deletions
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22
drivers/md/bitmap.c
View File

@ -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);
set_bit(bit, kaddr);
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 */
clear_bit(file_page_offset(j), page_address(page));
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);

2
drivers/md/md.c
View File

@ -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"))

11
include/linux/raid/bitmap.h
View File

@ -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 */

4
include/linux/raid/md.h
View File

@ -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);