On Tue, Jun 30, 2020 at 12:55 AM Xiao Ni <xni@xxxxxxxxxx> wrote:
>
> One super1.0 raid array wants to grow size, it needs to check the device max usable
> size. If the requested size is bigger than max usable size, it will return an error.
>
> Now it uses rdev->sectors for max usable size. If one disk is 500G and the raid device
> only uses the 100GB of this disk. rdev->sectors can't tell the real max usable size.
> The max usable size should be dev_size-(superblock_size+bitmap_size+badblock_size).
>
> Signed-off-by: Xiao Ni <xni@xxxxxxxxxx>
Thanks for the fix!
> ---
> drivers/md/md.c | 26 +++++++++++++++++++++++---
> 1 file changed, 23 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index f567f53..d2c5984 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -2183,10 +2183,30 @@ super_1_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
> return 0;
> } else {
> /* minor version 0; superblock after data */
> - sector_t sb_start;
> - sb_start = (i_size_read(rdev->bdev->bd_inode) >> 9) - 8*2;
> + sector_t sb_start, bm_space;
> + sector_t dev_size = i_size_read(rdev->bdev->bd_inode) >> 9;
> +
> + /* 8K is for superblock */
> + sb_start = dev_size - 8*2;
> sb_start &= ~(sector_t)(4*2 - 1);
> - max_sectors = rdev->sectors + sb_start - rdev->sb_start;
> +
> + /* if the device is bigger than 8Gig, save 64k for bitmap usage,
> + * if bigger than 200Gig, save 128k
> + */
> + if (dev_size < 64*2)
> + bm_space = 0;
> + else if (dev_size - 64*2 >= 200*1024*1024*2)
> + bm_space = 128*2;
> + else if (dev_size - 4*2 > 8*1024*1024*2)
> + bm_space = 64*2;
> + else
> + bm_space = 4*2;
Could you explain the handling of bitmap space?
Thanks,
Song
