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>
---
fs/btrfs/ioctl.c | 12 +++++++++---
1 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 14f8e1f..f056469 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3212,8 +3212,9 @@ 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;
@@ -3225,6 +3226,10 @@ 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);
@@ -3291,6 +3296,7 @@ out_bargs:
out:
mutex_unlock(&fs_info->balance_mutex);
mutex_unlock(&fs_info->volume_mutex);
+ mnt_drop_write(file->f_path.mnt);
return ret;
}
@@ -3386,7 +3392,7 @@ 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:
@@ -3419,7 +3425,7 @@ 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:
--
1.6.5.2
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