lustre/kernel_patches/patches/__find_get_block_slow-scale.patch

   1 Index: linux/fs/buffer.c
   2 ===================================================================
   3 --- linux.orig/fs/buffer.c
   4 +++ linux/fs/buffer.c
   5 @@ -509,13 +509,18 @@ __find_get_block_slow(struct block_devic
   6         struct buffer_head *head;
   7         struct page *page;
   8         int all_mapped = 1;
   9 +       int spinlock = 0;
  10
  11         index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits);
  12         page = find_get_page(bd_mapping, index);
  13         if (!page)
  14                 goto out;
  15
  16 +       if (unlikely(TestSetPageLocked(page))) {
  17         spin_lock(&bd_mapping->private_lock);
  18 +               spinlock = 1;
  19 +       }
  20 +
  21         if (!page_has_buffers(page))
  22                 goto out_unlock;
  23         head = page_buffers(page);
  24 @@ -536,7 +541,7 @@ __find_get_block_slow(struct block_devic
  25          * file io on the block device and getblk.  It gets dealt with
  26          * elsewhere, don't buffer_error if we had some unmapped buffers
  27          */
  28 -       if (all_mapped) {
  29 +       if (unlikely(all_mapped)) {
  30                 printk("__find_get_block_slow() failed. "
  31                         "block=%llu, b_blocknr=%llu\n",
  32                         (unsigned long long)block, (unsigned long long)bh->b_blocknr);
  33 @@ -544,7 +549,10 @@ __find_get_block_slow(struct block_devic
  34                 printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits);
  35         }
  36  out_unlock:
  37 +       if (unlikely(spinlock))
  38         spin_unlock(&bd_mapping->private_lock);
  39 +       else
  40 +               unlock_page(page);
  41         page_cache_release(page);
  42  out:
  43         return ret;