| Message ID | 1C24A869E87C7B45BE3E2BB439AB8F8C0D13DAE0@G5W2738.americas.hpqcorp.net (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
On Wed, Apr 23, 2014 at 2:28 PM, J S, Ajesh <ajesh.js@hp.com> wrote: > From: Ajesh JS <ajesh.js@hp.com> > > This patch provides a mechanism to modify the permission of a subvolume in a btrfs file system > This helps to apply a policy of having read-write subvolume inside a read-only subvolume. > One use case is to have the whole root file system as a read-only subvolume and have /etc as a read-write subvolume inside. Hi, Why doesn't the existing properties feature (3.14) work for you? Example: $ mkfs.btrfs -f /dev/sdd $ mount /dev/sdd /mnt/sdd $ btrfs subvolume create /mnt/sdd/topsubvol $ btrfs subvolume create /mnt/sdd/topsubvol/child $ btrfs property set /mnt/sdd/topsubvol ro true $ touch /mnt/sdd/topsubvol/file $ touch: cannot touch ‘/mnt/sdd/topsubvol/file’: Read-only file system $ touch /mnt/sdd/topsubvol/child/file The property set/get just uses the ioctls BTRFS_IOC_SUBVOL_SETFLAGS and BTRFS_IOC_SUBVOL_GETFLAGS. thanks > > Signed-off-by: Ajesh JS <ajesh.js@hp.com> > Reviewed-by: Liverance Fletcher <fletch@hp.com>; Clemenceau, <Matthieu matthieu.clemenceau@hp.com> > "-------------------------------------------------------------------------" > diff -rup linux-3.13.6/fs/btrfs/ioctl.c linux-3.13.6_btrfs/fs/btrfs/ioctl.c > --- linux-3.13.6/fs/btrfs/ioctl.c 2014-03-07 11:37:02.000000000 +0530 > +++ linux-3.13.6_btrfs/fs/btrfs/ioctl.c 2014-03-19 14:25:28.375139699 +0530 > @@ -1636,6 +1636,68 @@ out: > return ret; > } > > +static noinline int btrfs_ioctl_subvol_modify(struct file *file, > + void __user *arg) > +{ > + struct btrfs_ioctl_vol_args_v2 *vol_args; > + struct inode *inode = file_inode(file); > + struct btrfs_root *root = BTRFS_I(inode)->root; > + struct btrfs_trans_handle *trans; > + u64 root_flags; > + u64 flags; > + int ret = 0; > + > + ret = mnt_want_write_file(file); > + if (ret) > + goto out; > + > + if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID) { > + ret = -EINVAL; > + goto out_drop_write; > + } > + vol_args = memdup_user(arg, sizeof(*vol_args)); > + if (IS_ERR(vol_args)) > + goto out_drop_write; > + vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0'; > + flags = vol_args->flags; > + if (!inode_owner_or_capable(inode)) { > + ret = -EACCES; > + goto out_drop_write; > + } > + > + down_write(&root->fs_info->subvol_sem); > + root_flags = btrfs_root_flags(&root->root_item); > + > + if (flags & BTRFS_SUBVOL_RDONLY) { > + btrfs_set_root_flags(&root->root_item, > + root_flags | BTRFS_ROOT_SUBVOL_RDONLY); > + printk(KERN_INFO "Setting %s to ro\n", vol_args->name); > + } else { > + btrfs_set_root_flags(&root->root_item, > + root_flags & ~BTRFS_ROOT_SUBVOL_RDONLY); > + printk(KERN_INFO "Setting %s to rw\n", vol_args->name); > + } > + > + trans = btrfs_start_transaction(root, 1); > + if (IS_ERR(trans)) { > + ret = PTR_ERR(trans); > + goto out_reset; > + } > + > + ret = btrfs_update_root(trans, root->fs_info->tree_root, > + &root->root_key, &root->root_item); > + btrfs_commit_transaction(trans, root); > + > +out_reset: > + if (ret) > + btrfs_set_root_flags(&root->root_item, root_flags); > + up_write(&root->fs_info->subvol_sem); > +out_drop_write: > + mnt_drop_write_file(file); > +out: > + return ret; > +} > + > static noinline int btrfs_ioctl_subvol_getflags(struct file *file, > void __user *arg) > { > @@ -4509,6 +4571,8 @@ long btrfs_ioctl(struct file *file, unsi > return btrfs_ioctl_snap_create(file, argp, 1); > case BTRFS_IOC_SUBVOL_CREATE_V2: > return btrfs_ioctl_snap_create_v2(file, argp, 1); > + case BTRFS_IOC_SUBVOL_MODIFY: > + return btrfs_ioctl_subvol_modify(file, argp); > case BTRFS_IOC_SNAP_DESTROY: > return btrfs_ioctl_snap_destroy(file, argp); > case BTRFS_IOC_SUBVOL_GETFLAGS: > diff -rup linux-3.13.6/include/uapi/linux/btrfs.h linux-3.13.6_btrfs/include/uapi/linux/btrfs.h > --- linux-3.13.6/include/uapi/linux/btrfs.h 2014-03-07 11:37:02.000000000 +0530 > +++ linux-3.13.6_btrfs/include/uapi/linux/btrfs.h 2014-03-19 15:34:30.648255239 +0530 > @@ -606,5 +606,7 @@ static inline char *btrfs_err_str(enum b > struct btrfs_ioctl_dev_replace_args) > #define BTRFS_IOC_FILE_EXTENT_SAME _IOWR(BTRFS_IOCTL_MAGIC, 54, \ > struct btrfs_ioctl_same_args) > +#define BTRFS_IOC_SUBVOL_MODIFY _IOW(BTRFS_IOCTL_MAGIC, 55, \ > + struct btrfs_ioctl_vol_args_v2) > > #endif /* _UAPI_LINUX_BTRFS_H */ > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
diff -rup linux-3.13.6/fs/btrfs/ioctl.c linux-3.13.6_btrfs/fs/btrfs/ioctl.c --- linux-3.13.6/fs/btrfs/ioctl.c 2014-03-07 11:37:02.000000000 +0530 +++ linux-3.13.6_btrfs/fs/btrfs/ioctl.c 2014-03-19 14:25:28.375139699 +0530 @@ -1636,6 +1636,68 @@ out: return ret; } +static noinline int btrfs_ioctl_subvol_modify(struct file *file, + void __user *arg) +{ + struct btrfs_ioctl_vol_args_v2 *vol_args; + struct inode *inode = file_inode(file); + struct btrfs_root *root = BTRFS_I(inode)->root; + struct btrfs_trans_handle *trans; + u64 root_flags; + u64 flags; + int ret = 0; + + ret = mnt_want_write_file(file); + if (ret) + goto out; + + if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID) { + ret = -EINVAL; + goto out_drop_write; + } + vol_args = memdup_user(arg, sizeof(*vol_args)); + if (IS_ERR(vol_args)) + goto out_drop_write; + vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0'; + flags = vol_args->flags; + if (!inode_owner_or_capable(inode)) { + ret = -EACCES; + goto out_drop_write; + } + + down_write(&root->fs_info->subvol_sem); + root_flags = btrfs_root_flags(&root->root_item); + + if (flags & BTRFS_SUBVOL_RDONLY) { + btrfs_set_root_flags(&root->root_item, + root_flags | BTRFS_ROOT_SUBVOL_RDONLY); + printk(KERN_INFO "Setting %s to ro\n", vol_args->name); + } else { + btrfs_set_root_flags(&root->root_item, + root_flags & ~BTRFS_ROOT_SUBVOL_RDONLY); + printk(KERN_INFO "Setting %s to rw\n", vol_args->name); + } + + trans = btrfs_start_transaction(root, 1); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + goto out_reset; + } + + ret = btrfs_update_root(trans, root->fs_info->tree_root, + &root->root_key, &root->root_item); + btrfs_commit_transaction(trans, root); + +out_reset: + if (ret) + btrfs_set_root_flags(&root->root_item, root_flags); + up_write(&root->fs_info->subvol_sem); +out_drop_write: + mnt_drop_write_file(file); +out: + return ret; +} + static noinline int btrfs_ioctl_subvol_getflags(struct file *file, void __user *arg) { @@ -4509,6 +4571,8 @@ long btrfs_ioctl(struct file *file, unsi return btrfs_ioctl_snap_create(file, argp, 1); case BTRFS_IOC_SUBVOL_CREATE_V2: return btrfs_ioctl_snap_create_v2(file, argp, 1); + case BTRFS_IOC_SUBVOL_MODIFY: + return btrfs_ioctl_subvol_modify(file, argp); case BTRFS_IOC_SNAP_DESTROY: return btrfs_ioctl_snap_destroy(file, argp); case BTRFS_IOC_SUBVOL_GETFLAGS: diff -rup linux-3.13.6/include/uapi/linux/btrfs.h linux-3.13.6_btrfs/include/uapi/linux/btrfs.h --- linux-3.13.6/include/uapi/linux/btrfs.h 2014-03-07 11:37:02.000000000 +0530 +++ linux-3.13.6_btrfs/include/uapi/linux/btrfs.h 2014-03-19 15:34:30.648255239 +0530 @@ -606,5 +606,7 @@ static inline char *btrfs_err_str(enum b struct btrfs_ioctl_dev_replace_args) #define BTRFS_IOC_FILE_EXTENT_SAME _IOWR(BTRFS_IOCTL_MAGIC, 54, \ struct btrfs_ioctl_same_args) +#define BTRFS_IOC_SUBVOL_MODIFY _IOW(BTRFS_IOCTL_MAGIC, 55, \ + struct btrfs_ioctl_vol_args_v2) #endif /* _UAPI_LINUX_BTRFS_H */