Re: [PATCH V2] btrfs: Add a new mount option to grow the FS to the limit of the device

[Donggeun Kim <dg77.kim@samsung.com>]

Hi.
I sent the patch about one month ago.
I wonder this patch can be acceptable for the next kernel.
Otherwise, should I modify the patch again?
Please let me know it.

Thank you.
Donggeun Kim

Donggeun Kim wrote:
> Changes from V1 to V2:
> - A device id for resizing should be specified
>   when executing 'maxsize' mount option.
> 
> In some cases, resizing a file system to the maximum device size is required.
> When flashing a file system image to a block device,
> the file system does not fit into the block device's size.
> Currently, executing 'btrfsctl' application is the only way
> to grow the file system to the limit of the device.
> If the mount option which alters the device size of a file system
> to the limit of the device is supported,
> it can be useful regardless of the existence of 'btrfsctl' program.
> This patch allows the file system to grow to the maximum size of the device
> on mount time.
> The new mount option name is 'maxsize'.
> 
> Thank you.
> Donggeun Kim
> 
> Signed-off-by: Donggeun Kim <dg77.kim@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> ---
>  fs/btrfs/ctree.h   |    3 +++
>  fs/btrfs/disk-io.c |   30 ++++++++++++++++++++++++++++++
>  fs/btrfs/super.c   |   16 +++++++++++++++-
>  3 files changed, 48 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index e9bf864..865140e 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -1009,6 +1009,8 @@ struct btrfs_fs_info {
>  	unsigned data_chunk_allocations;
>  	unsigned metadata_ratio;
>  
> +	u64 maxsize_devid;
> +
>  	void *bdev_holder;
>  };
>  
> @@ -1192,6 +1194,7 @@ struct btrfs_root {
>  #define BTRFS_MOUNT_NOSSD		(1 << 9)
>  #define BTRFS_MOUNT_DISCARD		(1 << 10)
>  #define BTRFS_MOUNT_FORCE_COMPRESS      (1 << 11)
> +#define BTRFS_MOUNT_MAXSIZE		(1 << 12)
>  
>  #define btrfs_clear_opt(o, opt)		((o) &= ~BTRFS_MOUNT_##opt)
>  #define btrfs_set_opt(o, opt)		((o) |= BTRFS_MOUNT_##opt)
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 34f7c37..653fc8b 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -1533,6 +1533,9 @@ struct btrfs_root *open_ctree(struct super_block *sb,
>  	u32 stripesize;
>  	u64 generation;
>  	u64 features;
> +	u64 dev_max_size;
> +	u64 dev_old_size;
> +	u64 devid;
>  	struct btrfs_key location;
>  	struct buffer_head *bh;
>  	struct btrfs_root *extent_root = kzalloc(sizeof(struct btrfs_root),
> @@ -1554,6 +1557,9 @@ struct btrfs_root *open_ctree(struct super_block *sb,
>  
>  	struct btrfs_super_block *disk_super;
>  
> +	struct btrfs_trans_handle *trans;
> +	struct btrfs_device *device;
> +
>  	if (!extent_root || !tree_root || !fs_info ||
>  	    !chunk_root || !dev_root || !csum_root) {
>  		err = -ENOMEM;
> @@ -1928,6 +1934,30 @@ struct btrfs_root *open_ctree(struct super_block *sb,
>  		btrfs_set_opt(fs_info->mount_opt, SSD);
>  	}
>  
> +	if (btrfs_test_opt(tree_root, MAXSIZE)) {
> +		devid = fs_info->maxsize_devid;
> +		device = btrfs_find_device(tree_root, devid, NULL, NULL);
> +		if (!device) {
> +			printk(KERN_WARNING "resizer unable to "
> +				"find device %llu\n",
> +				(unsigned long long)devid);
> +			goto fail_trans_kthread;
> +		}
> +		dev_max_size = device->bdev->bd_inode->i_size;
> +		dev_old_size = device->total_bytes;
> +		if (dev_max_size > dev_old_size) {
> +			trans = btrfs_start_transaction(tree_root, 0);
> +			ret = btrfs_grow_device(trans, device, dev_max_size);
> +			if (ret)
> +				printk(KERN_INFO "unable to resize for %s\n",
> +					device->name);
> +			else
> +				printk(KERN_INFO "new size for %s is %llu\n",
> +					device->name, dev_max_size);
> +			btrfs_commit_transaction(trans, tree_root);
> +		}
> +	}
> +
>  	if (btrfs_super_log_root(disk_super) != 0) {
>  		u64 bytenr = btrfs_super_log_root(disk_super);
>  
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 859ddaa..b280980 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -68,7 +68,7 @@ enum {
>  	Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
>  	Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
>  	Opt_compress_force, Opt_notreelog, Opt_ratio, Opt_flushoncommit,
> -	Opt_discard, Opt_err,
> +	Opt_discard, Opt_maxsize, Opt_err,
>  };
>  
>  static match_table_t tokens = {
> @@ -92,6 +92,7 @@ static match_table_t tokens = {
>  	{Opt_flushoncommit, "flushoncommit"},
>  	{Opt_ratio, "metadata_ratio=%d"},
>  	{Opt_discard, "discard"},
> +	{Opt_maxsize, "maxsize=%d"},
>  	{Opt_err, NULL},
>  };
>  
> @@ -235,6 +236,17 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
>  		case Opt_discard:
>  			btrfs_set_opt(info->mount_opt, DISCARD);
>  			break;
> +		case Opt_maxsize:
> +			intarg = 0;
> +			match_int(&args[0], &intarg);
> +			if (intarg) {
> +				info->maxsize_devid = intarg;
> +				printk(KERN_INFO
> +					"btrfs: maxsize for devid %llu\n",
> +					info->maxsize_devid);
> +			}
> +			btrfs_set_opt(info->mount_opt, MAXSIZE);
> +			break;
>  		case Opt_err:
>  			printk(KERN_INFO "btrfs: unrecognized mount option "
>  			       "'%s'\n", p);
> @@ -541,6 +553,8 @@ static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
>  		seq_puts(seq, ",flushoncommit");
>  	if (btrfs_test_opt(root, DISCARD))
>  		seq_puts(seq, ",discard");
> +	if (btrfs_test_opt(root, MAXSIZE))
> +		seq_printf(seq, ",maxsize=%llu", info->maxsize_devid);
>  	if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
>  		seq_puts(seq, ",noacl");
>  	return 0;