[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: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 1be3f2d..be7873c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -393,7 +393,7 @@
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 @@
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 @@
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 @@
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 @@
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 @@
}
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 @@
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 @@
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),