On Thu, August 23, 2012 at 10:56 (+0200), Liu Bo wrote:
> This is the change of the kernel side.
> 
> Transition of logical to inode used to have a limit 4096 on inode container's
> size, but the limit is not large enough for a data with a great many of refs,
> so when resolving logical address, we can end up with
> "ioctl ret=0, bytes_left=0, bytes_missing=19944, cnt=510, missed=2493"
> 
> This changes to regard 4096 as the lowest limit.
> 
> Signed-off-by: Liu Bo <bo.li....@oracle.com>
> ---
>  fs/btrfs/ioctl.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 9449b84..525915f 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -3232,7 +3232,7 @@ static long btrfs_ioctl_logical_to_ino(struct 
> btrfs_root *root,
>               goto out;
>       }
>  
> -     size = min_t(u32, loi->size, 4096);
> +     size = max_t(u32, loi->size, 4096);

Hum. I added this because I wanted to avoid allocations > PAGE_SIZE. We're doing
kmalloc GFP_NOFS with whatever one enters as size, I'm not sure that's a good
idea without any sanitizing.

Second, we should probably add a fall back option to vmalloc, in case kmalloc
fails? Or should we even go for vmalloc directly, what do you think?

Thanks,
-Jan

>       inodes = init_data_container(size);
>       if (IS_ERR(inodes)) {
>               ret = PTR_ERR(inodes);

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