On Tue, Jul 08, 2014 at 02:38:37AM +0800, Anand Jain wrote:
> (for review comments pls).
>
> btrfs_scan_one_device() needs SB, instead of doing it from scratch could
> use btrfs_get_bdev_and_sb()
>
> Signed-off-by: Anand Jain <Anand.Jain@xxxxxxxxxx>
> ---
> fs/btrfs/volumes.c | 51 ++++++---------------------------------------------
> 1 file changed, 6 insertions(+), 45 deletions(-)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index c166355..94e6131 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -1053,14 +1053,11 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
> {
> struct btrfs_super_block *disk_super;
> struct block_device *bdev;
> - struct page *page;
> - void *p;
> int ret = -EINVAL;
> u64 devid;
> u64 transid;
> u64 total_devices;
> - u64 bytenr;
> - pgoff_t index;
> + struct buffer_head *bh;
>
> /*
> * we would like to check all the supers, but that would make
> @@ -1068,44 +1065,12 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
> * So, we need to add a special mount option to scan for
> * later supers, using BTRFS_SUPER_MIRROR_MAX instead
> */
> - bytenr = btrfs_sb_offset(0);
> mutex_lock(&uuid_mutex);
>
> - bdev = blkdev_get_by_path(path, flags, holder);
> -
> - if (IS_ERR(bdev)) {
> - ret = PTR_ERR(bdev);
> + ret = btrfs_get_bdev_and_sb(path, flags, holder, 0, &bdev, &bh);
> + if (ret)
> goto error;
> - }
> -
> - /* make sure our super fits in the device */
> - if (bytenr + PAGE_CACHE_SIZE >= i_size_read(bdev->bd_inode))
> - goto error_bdev_put;
> -
> - /* make sure our super fits in the page */
> - if (sizeof(*disk_super) > PAGE_CACHE_SIZE)
> - goto error_bdev_put;
> -
> - /* make sure our super doesn't straddle pages on disk */
> - index = bytenr >> PAGE_CACHE_SHIFT;
> - if ((bytenr + sizeof(*disk_super) - 1) >> PAGE_CACHE_SHIFT != index)
> - goto error_bdev_put;
Apparently btrfs_get_bdev_and_sb() lacks the above two checks, otherwise looks good.
thanks,
-liubo
> -
> - /* pull in the page with our super */
> - page = read_cache_page_gfp(bdev->bd_inode->i_mapping,
> - index, GFP_NOFS);
> -
> - if (IS_ERR_OR_NULL(page))
> - goto error_bdev_put;
> -
> - p = kmap(page);
> -
> - /* align our pointer to the offset of the super block */
> - disk_super = p + (bytenr & ~PAGE_CACHE_MASK);
> -
> - if (btrfs_super_bytenr(disk_super) != bytenr ||
> - btrfs_super_magic(disk_super) != BTRFS_MAGIC)
> - goto error_unmap;
> + disk_super = (struct btrfs_super_block *) bh->b_data;
>
> devid = btrfs_stack_device_id(&disk_super->dev_item);
> transid = btrfs_super_generation(disk_super);
> @@ -1125,13 +1090,9 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
> printk(KERN_CONT "devid %llu transid %llu %s\n", devid, transid, path);
> }
>
> -
> -error_unmap:
> - kunmap(page);
> - page_cache_release(page);
> -
> -error_bdev_put:
> + brelse(bh);
> blkdev_put(bdev, flags);
> +
> error:
> mutex_unlock(&uuid_mutex);
> return ret;
> --
> 2.0.0.257.g75cc6c6
>
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