Torsten Hilbrich <torsten.hilbrich@xxxxxxxxxxx> writes:
> The system where I reproduced the problem upstream is an amd64 based
> ubuntu 12.04 installation. I used both v3.3.8 and v3.4 for reproducing.
>
> The partition layout is the following:
>
> ======================================================================
>
> Disk /dev/sda: 120.0 GB, 120034123776 bytes
> 255 heads, 63 sectors/track, 14593 cylinders, total 234441648 sectors
> Units = sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disk identifier: 0x1669c708
>
> Device Boot Start End Blocks Id System
> /dev/sda1 * 63 86285114 43142526 83 Linux
> /dev/sda2 216797175 234436544 8819685 82 Linux swap / Solaris
> /dev/sda3 86285115 87088364 401625 83 Linux
> /dev/sda4 87088426 216797174 64854374+ 5 Extended
> /dev/sda5 87088428 91104614 2008093+ 83 Linux
> /dev/sda6 91104678 216797174 62846248+ 8e Linux LVM
>
> Partition table entries are not in disk order
OK, got it to reproduce, thanks for the info. The attached patch fixed
the problem for me.
Note, though, that the patch doesn't make sense to me. blkdev_max_block
returns i_size_read(blkdev_inode) >> block_size. This should be the
*size* of the block device, not the max block. The code in
fs/block_device.c uses the return value in two different ways!
static int
blkdev_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh, int create)
{
if (iblock >= blkdev_max_block(I_BDEV(inode))) {
Here, the return value from blkdev_max_block is interpreted as the size
of the device, so actually max_block + 1.
static int
blkdev_get_blocks(struct inode *inode, sector_t iblock,
struct buffer_head *bh, int create)
{
sector_t end_block = blkdev_max_block(I_BDEV(inode));
unsigned long max_blocks = bh->b_size >> inode->i_blkbits;
if ((iblock + max_blocks) > end_block) {
Here, the return value is treated as the maximum addressable block
number. Given the fact that I had to modify init_page_buffers to treat
the return value from blkdev_max_block as the maximum addressable block,
I clearly have something wrong with my logic. Nick, Jens, care to set
my head straight?
Cheers,
Jeff
diff --git a/fs/buffer.c b/fs/buffer.c
index 838a9cf..769b30b 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -930,7 +930,7 @@ init_page_buffers(struct page *page, struct block_device *bdev,
bh->b_blocknr = block;
if (uptodate)
set_buffer_uptodate(bh);
- if (block < end_block)
+ if (block <= end_block)
set_buffer_mapped(bh);
}
block++;
--
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