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Btrfs: do not do balance in readonly mode

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In normal cases, we would not be allowed to do balance in RO mode.
However, when we're using a seeding device and adding another device to sprout,
things will change:

$ mkfs.btrfs /dev/sdb7
$ btrfstune -S 1 /dev/sdb7
$ mount /dev/sdb7 /mnt/btrfs -o ro
$ btrfs fi bal /mnt/btrfs   -----------------------> fail.
$ btrfs dev add /dev/sdb8 /mnt/btrfs
$ btrfs fi bal /mnt/btrfs   -----------------------> works!

It should not be designed as an exception, and we'd better add another check for
mnt flags.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Reviewed-by: Josef Bacik <josef@redhat.com>
This commit is contained in:
Liu Bo 2012-05-11 18:11:26 +08:00 committed by Josef Bacik
parent d1ac6e41d5
commit 9ba1f6e44e
1 changed files with 9 additions and 3 deletions
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12
fs/btrfs/ioctl.c
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@ -3216,8 +3216,9 @@ void update_ioctl_balance_args(struct btrfs_fs_info *fs_info, int lock,
}
}
static long btrfs_ioctl_balance(struct btrfs_root *root, void __user *arg)
static long btrfs_ioctl_balance(struct file *file, void __user *arg)
{
struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_ioctl_balance_args *bargs;
struct btrfs_balance_control *bctl;
@ -3229,6 +3230,10 @@ static long btrfs_ioctl_balance(struct btrfs_root *root, void __user *arg)
if (fs_info->sb->s_flags & MS_RDONLY)
return -EROFS;
ret = mnt_want_write(file->f_path.mnt);
if (ret)
return ret;
mutex_lock(&fs_info->volume_mutex);
mutex_lock(&fs_info->balance_mutex);
@ -3295,6 +3300,7 @@ static long btrfs_ioctl_balance(struct btrfs_root *root, void __user *arg)
out:
mutex_unlock(&fs_info->balance_mutex);
mutex_unlock(&fs_info->volume_mutex);
mnt_drop_write(file->f_path.mnt);
return ret;
}
@ -3390,7 +3396,7 @@ long btrfs_ioctl(struct file *file, unsigned int
case BTRFS_IOC_DEV_INFO:
return btrfs_ioctl_dev_info(root, argp);
case BTRFS_IOC_BALANCE:
return btrfs_ioctl_balance(root, NULL);
return btrfs_ioctl_balance(file, NULL);
case BTRFS_IOC_CLONE:
return btrfs_ioctl_clone(file, arg, 0, 0, 0);
case BTRFS_IOC_CLONE_RANGE:
@ -3423,7 +3429,7 @@ long btrfs_ioctl(struct file *file, unsigned int
case BTRFS_IOC_SCRUB_PROGRESS:
return btrfs_ioctl_scrub_progress(root, argp);
case BTRFS_IOC_BALANCE_V2:
return btrfs_ioctl_balance(root, argp);
return btrfs_ioctl_balance(file, argp);
case BTRFS_IOC_BALANCE_CTL:
return btrfs_ioctl_balance_ctl(root, arg);
case BTRFS_IOC_BALANCE_PROGRESS: