src/patches/suse-2.6.27.31/patches.suse/md-raid-metadata-PAGE_SIZE.patch

   1 Subject: [Bug 429490] sles10 raid0 can not be started
   2 From: bugzilla_noreply@novell.com
   3
   4 ### Comment #4 from Neil Brown <nfbrown@novell.com>  2008-10-08 17:34:49 MDT ---
   5 The md code was written with the expectation that the chunk size would
   6 always be at least one page.  This may not always be a strict requirement,
   7 but I guess that test protects against untested code.
   8
   9 For raid4/5/6, the stripe-cache is stored as pages so a chunk size
  10 less than one page would certainly cause problems with the current code.
  11
  12 For raid0, I think a smaller chunk size should work.
  13 The filesystem is always allowed to send down one-page requests, and
  14 if the chunk size is less than that page size, these requests will have
  15 to be split up, possibly multiple times.  However I think the code will
  16 get this right - it has only actually be used for page-sized requests
  17 that are not page-aligned.
  18
  19 You could try changing the test to
  20
  21   if (chunk_size < PAGE_SIZE && mddev->level != 0) {
  22
  23 and see how that works.
  24
  25 Signed-off-by: Olaf Hering <olh@suse.de>
  26
  27 ---
  28  drivers/md/md.c |    5 +++++
  29  1 file changed, 5 insertions(+)
  30
  31 --- a/drivers/md/md.c
  32 +++ b/drivers/md/md.c
  33 @@ -3587,9 +3587,14 @@ static int do_md_run(mddev_t * mddev)
  34                         return -EINVAL;
  35                 }
  36                 if (chunk_size < PAGE_SIZE) {
  37 +                       if (mddev->level) {
  38                         printk(KERN_ERR "too small chunk_size: %d < %ld\n",
  39                                 chunk_size, PAGE_SIZE);
  40                         return -EINVAL;
  41 +                       } else {
  42 +                               printk(KERN_ERR "too small chunk_size: %d < %ld, but continuing anyway on raid0. Good luck!\n",
  43 +                                       chunk_size, PAGE_SIZE);
  44 +                       }
  45                 }
  46
  47                 /* devices must have minimum size of one chunk */