The patch titled

     md: limit size of sb read/written to appropriate amount

has been added to the -mm tree.  Its filename is

     md-limit-size-of-sb-read-written-to-appropriate-amount.patch

Patches currently in -mm which might be from [EMAIL PROTECTED] are

sunrpc-cache_register-can-use-wrong-module-reference.patch
md-fix-minor-error-in-raid10-read-balancing-calculation.patch
md-fail-io-request-to-md-that-require-a-barrier.patch
md-dont-allow-new-md-bitmap-file-to-be-set-if-one-already-exists.patch
md-improve-handling-of-bitmap-initialisation.patch
md-all-hot-add-and-hot-remove-of-md-intent-logging-bitmaps.patch
md-support-write-mostly-device-in-raid1.patch
md-add-write-behind-support-for-md-raid1.patch
md-support-md-linear-array-with-components-greater-than-2-terabytes.patch
md-raid1_quiesce-is-back-to-front-fix-it.patch
md-make-sure-bitmap_daemon_work-actually-does-work.patch
md-do-not-set-mddev-bitmap-until-bitmap-is-fully-initialised.patch
md-allow-hot-adding-devices-to-arrays-with-non-persistant-superblocks.patch
md-allow-md-to-load-a-superblock-with-feature-bit-1-set.patch
md-fix-bitmap-read_sb_page-so-that-it-handles-errors-properly.patch
md-remove-old-cruft-from-md_kh-header-file.patch
md-limit-size-of-sb-read-written-to-appropriate-amount.patch
md-add-write-intent-bitmap-support-to-raid5.patch
md-write-intent-bitmap-support-for-raid6.patch
md-use-kthread-infrastructure-in-md.patch
md-ensure-bitmap_writeback_daemon-handles-shutdown-properly.patch
md-tidy-up-daemon-stop-start-code-in-md-bitmapc.patch
drivers-md-fix-up-schedule_timeout-usage.patch



From: NeilBrown <[EMAIL PROTECTED]>

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 <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
---

 drivers/md/md.c           |   20 +++++++++++++++-----
 include/linux/raid/md_k.h |    1 +
 2 files changed, 16 insertions(+), 5 deletions(-)

diff -puN 
drivers/md/md.c~md-limit-size-of-sb-read-written-to-appropriate-amount 
drivers/md/md.c
--- 
devel/drivers/md/md.c~md-limit-size-of-sb-read-written-to-appropriate-amount    
    2005-08-29 23:44:25.000000000 -0700
+++ devel-akpm/drivers/md/md.c  2005-08-29 23:44:26.000000000 -0700
@@ -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 -puN 
include/linux/raid/md_k.h~md-limit-size-of-sb-read-written-to-appropriate-amount
 include/linux/raid/md_k.h
--- 
devel/include/linux/raid/md_k.h~md-limit-size-of-sb-read-written-to-appropriate-amount
      2005-08-29 23:44:25.000000000 -0700
+++ devel-akpm/include/linux/raid/md_k.h        2005-08-29 23:44:26.000000000 
-0700
@@ -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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