[dm-devel] introduce dm-snap-mv
Daniel Phillips
phillips at phunq.net
Thu Oct 7 21:31:14 UTC 2010
Hi Meng,
The patch looks sensible, however the question is: why do you want to
do this? Would it not be better to generalize your metadata format to
accomodate the device's native blocksize?
Regards,
Daniel
> a kernel patch
> --------------
> Now, dm-snap-mv highly depends on a kernel patch below, which make __getblk()
> can get a 4K buffer head while block size of the disk is NOT 4K.
>
> Signed-off-by: Cong Meng <mcpacino at gmail.com>
> ---
> fs/buffer.c | 7 ++-----
> 1 files changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/fs/buffer.c b/fs/buffer.c
> index 3e7dca2..f7f9d33 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -1051,10 +1051,7 @@ grow_buffers(struct block_device *bdev, sector_t block, int size)
> pgoff_t index;
> int sizebits;
>
> - sizebits = -1;
> - do {
> - sizebits++;
> - } while ((size << sizebits) < PAGE_SIZE);
> + sizebits = PAGE_CACHE_SHIFT - bdev->bd_inode->i_blkbits;
>
> index = block >> sizebits;
>
> @@ -2924,7 +2921,7 @@ int submit_bh(int rw, struct buffer_head * bh)
> */
> bio = bio_alloc(GFP_NOIO, 1);
>
> - bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
> + bio->bi_sector = bh->b_blocknr << (bh->b_bdev->bd_inode->i_blkbits - 9);
> bio->bi_bdev = bh->b_bdev;
> bio->bi_io_vec[0].bv_page = bh->b_page;
> bio->bi_io_vec[0].bv_len = bh->b_size;
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