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: Neil Brown <neilb@xxxxxxxxxxxxxxx>
### Diffstat output
./drivers/md/md.c | 20 +++++++++++++++-----
./include/linux/raid/md_k.h | 1 +
2 files changed, 16 insertions(+), 5 deletions(-)
diff ./drivers/md/md.c~current~ ./drivers/md/md.c
--- ./drivers/md/md.c~current~ 2005-08-29 15:52:32.000000000 +1000
+++ ./drivers/md/md.c 2005-08-29 15:52:47.000000000 +1000
@@ -393,7 +393,7 @@ int sync_page_io(struct block_device *bd
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 * rde
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 *rde
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 *rde
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
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
}
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
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 @@ repeat:
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),
diff ./include/linux/raid/md_k.h~current~ ./include/linux/raid/md_k.h
--- ./include/linux/raid/md_k.h~current~ 2005-08-29 15:52:38.000000000 +1000
+++ ./include/linux/raid/md_k.h 2005-08-29 15:52:47.000000000 +1000
@@ -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:
-
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