Btrfs devel - Dec 2011 - [PATCH] btrfs: change resize ioctl to take device path instead of id

The resize ioctl took an optional argument that was a string
representation of the devid which you wish to resize.  For
the sake of consistency with the other ioctls that take a
device argument, I converted this to take a device path instead
of a devid number, and look up the number from the path.

Signed-off-by: Phillip Susi <psusi@cfl.rr.com>
---
 fs/btrfs/ioctl.c |   33 ++++++++++++++++++++++++++-------
 1 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 72d4616..b4a0d46 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1211,13 +1211,32 @@ static noinline int btrfs_ioctl_resize(struct btrfs_root
*root,
 	sizestr = vol_args->name;
 	devstr = strchr(sizestr, '':'');
 	if (devstr) {
-		char *end;
-		sizestr = devstr + 1;
-		*devstr = ''\0'';
-		devstr = vol_args->name;
-		devid = simple_strtoull(devstr, &end, 10);
-		printk(KERN_INFO "btrfs: resizing devid %llu\n",
-		       (unsigned long long)devid);
+		struct block_device *bdev;
+		struct btrfs_super_block *disk_super;
+		struct buffer_head *bh;
+
+		*devstr = 0;
+		devstr++;
+		printk(KERN_INFO "btrfs: resizing device %s\n",
+			devstr);
+		bdev = blkdev_get_by_path(devstr, FMODE_READ | FMODE_EXCL,
+					  root->fs_info->bdev_holder);
+		if (IS_ERR(bdev)) {
+			ret = PTR_ERR(bdev);
+			goto out_unlock;
+		}
+
+		set_blocksize(bdev, 4096);
+		bh = btrfs_read_dev_super(bdev);
+		if (!bh) {
+			ret = -EINVAL;
+			blkdev_put(bdev, FMODE_READ | FMODE_EXCL);
+			goto out_unlock;
+		}
+		disk_super = (struct btrfs_super_block *)bh->b_data;
+		devid = btrfs_stack_device_id(&disk_super->dev_item);
+		brelse(bh);
+		blkdev_put(bdev, FMODE_READ | FMODE_EXCL);
 	}
 	device = btrfs_find_device(root, devid, NULL, NULL);
 	if (!device) {
-- 
1.7.5.4

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Phillip Susi wrote:
> The resize ioctl took an optional argument that was a string
> representation of the devid which you wish to resize.  For
> the sake of consistency with the other ioctls that take a
> device argument, I converted this to take a device path instead
> of a devid number, and look up the number from the path.
> 
but.. isn''t this an ABI change?

so instead of changing it, I think it''s ok to extend it.
> Signed-off-by: Phillip Susi <psusi@cfl.rr.com>
> ---
>  fs/btrfs/ioctl.c |   33 ++++++++++++++++++++++++++-------
>  1 files changed, 26 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 72d4616..b4a0d46 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -1211,13 +1211,32 @@ static noinline int btrfs_ioctl_resize(struct
btrfs_root *root,
>  	sizestr = vol_args->name;
>  	devstr = strchr(sizestr, '':'');
>  	if (devstr) {
> -		char *end;
> -		sizestr = devstr + 1;
> -		*devstr = ''\0'';
> -		devstr = vol_args->name;
> -		devid = simple_strtoull(devstr, &end, 10);
> -		printk(KERN_INFO "btrfs: resizing devid %llu\n",
> -		       (unsigned long long)devid);
> +		struct block_device *bdev;
> +		struct btrfs_super_block *disk_super;
> +		struct buffer_head *bh;
> +
> +		*devstr = 0;
> +		devstr++;
> +		printk(KERN_INFO "btrfs: resizing device %s\n",
> +			devstr);
> +		bdev = blkdev_get_by_path(devstr, FMODE_READ | FMODE_EXCL,
> +					  root->fs_info->bdev_holder);
> +		if (IS_ERR(bdev)) {
> +			ret = PTR_ERR(bdev);
> +			goto out_unlock;
> +		}
> +
> +		set_blocksize(bdev, 4096);
> +		bh = btrfs_read_dev_super(bdev);
> +		if (!bh) {
> +			ret = -EINVAL;
> +			blkdev_put(bdev, FMODE_READ | FMODE_EXCL);
> +			goto out_unlock;
> +		}
> +		disk_super = (struct btrfs_super_block *)bh->b_data;
> +		devid = btrfs_stack_device_id(&disk_super->dev_item);
> +		brelse(bh);
> +		blkdev_put(bdev, FMODE_READ | FMODE_EXCL);
>  	}
>  	device = btrfs_find_device(root, devid, NULL, NULL);
>  	if (!device) {
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 12/11/2011 10:31 PM, Li Zefan wrote:
> Phillip Susi wrote:
>> The resize ioctl took an optional argument that was a string
>> representation of the devid which you wish to resize.  For
>> the sake of consistency with the other ioctls that take a
>> device argument, I converted this to take a device path instead
>> of a devid number, and look up the number from the path.
>>
> 
> but.. isn''t this an ABI change?
Technically no, since the ABI is just a string that may (undocumented) have a
colon in it followed by digits.
> so instead of changing it, I think it''s ok to extend it.
I considered that at first, but the existing code appears to not handle errors (
what happens when the string can''t be converted to an integer? ) and
the interface has not been documented until now, so I figured may as well just
get rid of it.
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Bump.

On 12/11/2011 10:12 PM, Phillip Susi wrote:
> The resize ioctl took an optional argument that was a string
> representation of the devid which you wish to resize.  For
> the sake of consistency with the other ioctls that take a
> device argument, I converted this to take a device path instead
> of a devid number, and look up the number from the path.
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