Re: [PATCH 2/2 v2] Btrfs: Per file/directory controls for COW and compression

[liubo <liubo2009@cn.fujitsu.com>]

On 04/04/2011 05:31 PM, Konstantinos Skarlatos wrote:
> Hello,
> I would like to ask about the status of this feature/patch, is it
> accepted into btrfs code, and how can I use it?
>=20

Yes, it is now in the latest 2.6.39-rc1.

> I am interested in enabling compression in a specific
> folder(force-compress would be ideal) of a large btrfs volume, and
> disabling it for the rest.
>=20

hmm, I'm making the tool's patch, and will come soon. :)

>=20
> On 21/3/2011 10:57 =CF=80=CE=BC, liubo wrote:
>> Data compression and data cow are controlled across the entire FS by
>> mount
>> options right now.  ioctls are needed to set this on a per file or p=
er
>> directory basis.  This has been proposed previously, but VFS develop=
ers
>> wanted us to use generic ioctls rather than btrfs-specific ones.
>>
>> According to chris's comment, there should be just one true compress=
ion
>> method(probably LZO) stored in the super.  However, before this, we =
would
>> wait for that one method is stable enough to be adopted into the sup=
er.
>> So I list it as a long term goal, and just store it in ram today.
>>
>> After applying this patch, we can use the generic "FS_IOC_SETFLAGS"
>> ioctl to
>> control file and directory's datacow and compression attribute.
>>
>> NOTE:
>>   - The compression type is selected by such rules:
>>     If we mount btrfs with compress options, ie, zlib/lzo, the type =
is
>> it.
>>     Otherwise, we'll use the default compress type (zlib today).
>>
>> v1->v2:
>> Rebase the patch with the latest btrfs.
>>
>> Signed-off-by: Liu Bo<liubo2009@cn.fujitsu.com>
>> ---
>>   fs/btrfs/ctree.h   |    1 +
>>   fs/btrfs/disk-io.c |    6 ++++++
>>   fs/btrfs/inode.c   |   32 ++++++++++++++++++++++++++++----
>>   fs/btrfs/ioctl.c   |   41 +++++++++++++++++++++++++++++++++++++---=
-
>>   4 files changed, 72 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
>> index 8b4b9d1..b77d1a5 100644
>> --- a/fs/btrfs/ctree.h
>> +++ b/fs/btrfs/ctree.h
>> @@ -1283,6 +1283,7 @@ struct btrfs_root {
>>   #define BTRFS_INODE_NODUMP        (1<<  8)
>>   #define BTRFS_INODE_NOATIME        (1<<  9)
>>   #define BTRFS_INODE_DIRSYNC        (1<<  10)
>> +#define BTRFS_INODE_COMPRESS        (1<<  11)
>>
>>   /* some macros to generate set/get funcs for the struct fields.  T=
his
>>    * assumes there is a lefoo_to_cpu for every type, so lets make a
>> simple
>> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
>> index 3e1ea3e..a894c12 100644
>> --- a/fs/btrfs/disk-io.c
>> +++ b/fs/btrfs/disk-io.c
>> @@ -1762,6 +1762,12 @@ struct btrfs_root *open_ctree(struct
>> super_block *sb,
>>
>>       btrfs_check_super_valid(fs_info, sb->s_flags&  MS_RDONLY);
>>
>> +    /*
>> +     * In the long term, we'll store the compression type in the su=
per
>> +     * block, and it'll be used for per file compression control.
>> +     */
>> +    fs_info->compress_type =3D BTRFS_COMPRESS_ZLIB;
>> +
>>       ret =3D btrfs_parse_options(tree_root, options);
>>       if (ret) {
>>           err =3D ret;
>> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
>> index db67821..e687bb9 100644
>> --- a/fs/btrfs/inode.c
>> +++ b/fs/btrfs/inode.c
>> @@ -381,7 +381,8 @@ again:
>>        */
>>       if (!(BTRFS_I(inode)->flags&  BTRFS_INODE_NOCOMPRESS)&&
>>       (btrfs_test_opt(root, COMPRESS) ||
>> -         (BTRFS_I(inode)->force_compress))) {
>> +         (BTRFS_I(inode)->force_compress) ||
>> +         (BTRFS_I(inode)->flags&  BTRFS_INODE_COMPRESS))) {
>>           WARN_ON(pages);
>>           pages =3D kzalloc(sizeof(struct page *) * nr_pages, GFP_NO=
=46S);
>>
>> @@ -1253,7 +1254,8 @@ static int run_delalloc_range(struct inode
>> *inode, struct page *locked_page,
>>           ret =3D run_delalloc_nocow(inode, locked_page, start, end,
>>                        page_started, 0, nr_written);
>>       else if (!btrfs_test_opt(root, COMPRESS)&&
>> -         !(BTRFS_I(inode)->force_compress))
>> +         !(BTRFS_I(inode)->force_compress)&&
>> +         !(BTRFS_I(inode)->flags&  BTRFS_INODE_COMPRESS))
>>           ret =3D cow_file_range(inode, locked_page, start, end,
>>                         page_started, nr_written, 1);
>>       else
>> @@ -4581,8 +4583,6 @@ static struct inode *btrfs_new_inode(struct
>> btrfs_trans_handle *trans,
>>       location->offset =3D 0;
>>       btrfs_set_key_type(location, BTRFS_INODE_ITEM_KEY);
>>
>> -    btrfs_inherit_iflags(inode, dir);
>> -
>>       if ((mode&  S_IFREG)) {
>>           if (btrfs_test_opt(root, NODATASUM))
>>               BTRFS_I(inode)->flags |=3D BTRFS_INODE_NODATASUM;
>> @@ -4590,6 +4590,8 @@ static struct inode *btrfs_new_inode(struct
>> btrfs_trans_handle *trans,
>>               BTRFS_I(inode)->flags |=3D BTRFS_INODE_NODATACOW;
>>       }
>>
>> +    btrfs_inherit_iflags(inode, dir);
>> +
>>       insert_inode_hash(inode);
>>       inode_tree_add(inode);
>>       return inode;
>> @@ -6803,6 +6805,26 @@ static int btrfs_getattr(struct vfsmount *mnt=
,
>>       return 0;
>>   }
>>
>> +/*
>> + * If a file is moved, it will inherit the cow and compression flag=
s
>> of the new
>> + * directory.
>> + */
>> +static void fixup_inode_flags(struct inode *dir, struct inode *inod=
e)
>> +{
>> +    struct btrfs_inode *b_dir =3D BTRFS_I(dir);
>> +    struct btrfs_inode *b_inode =3D BTRFS_I(inode);
>> +
>> +    if (b_dir->flags&  BTRFS_INODE_NODATACOW)
>> +        b_inode->flags |=3D BTRFS_INODE_NODATACOW;
>> +    else
>> +        b_inode->flags&=3D ~BTRFS_INODE_NODATACOW;
>> +
>> +    if (b_dir->flags&  BTRFS_INODE_COMPRESS)
>> +        b_inode->flags |=3D BTRFS_INODE_COMPRESS;
>> +    else
>> +        b_inode->flags&=3D ~BTRFS_INODE_COMPRESS;
>> +}
>> +
>>   static int btrfs_rename(struct inode *old_dir, struct dentry
>> *old_dentry,
>>                  struct inode *new_dir, struct dentry *new_dentry)
>>   {
>> @@ -6936,6 +6958,8 @@ static int btrfs_rename(struct inode *old_dir,
>> struct dentry *old_dentry,
>>           }
>>       }
>>
>> +    fixup_inode_flags(new_dir, old_inode);
>> +
>>       ret =3D btrfs_add_link(trans, new_dir, old_inode,
>>                    new_dentry->d_name.name,
>>                    new_dentry->d_name.len, 0, index);
>> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
>> index 5fdb2ab..93e7f6c 100644
>> --- a/fs/btrfs/ioctl.c
>> +++ b/fs/btrfs/ioctl.c
>> @@ -138,6 +138,24 @@ static int btrfs_ioctl_getflags(struct file
>> *file, void __user *arg)
>>       return 0;
>>   }
>>
>> +static int check_flags(unsigned int flags)
>> +{
>> +    if (flags&  ~(FS_IMMUTABLE_FL | FS_APPEND_FL | \
>> +              FS_NOATIME_FL | FS_NODUMP_FL | \
>> +              FS_SYNC_FL | FS_DIRSYNC_FL | \
>> +              FS_NOCOMP_FL | FS_COMPR_FL | \
>> +              FS_NOCOW_FL | FS_COW_FL))
>> +        return -EOPNOTSUPP;
>> +
>> +    if ((flags&  FS_NOCOMP_FL)&&  (flags&  FS_COMPR_FL))
>> +        return -EINVAL;
>> +
>> +    if ((flags&  FS_NOCOW_FL)&&  (flags&  FS_COW_FL))
>> +        return -EINVAL;
>> +
>> +    return 0;
>> +}
>> +
>>   static int btrfs_ioctl_setflags(struct file *file, void __user *ar=
g)
>>   {
>>       struct inode *inode =3D file->f_path.dentry->d_inode;
>> @@ -153,10 +171,9 @@ static int btrfs_ioctl_setflags(struct file
>> *file, void __user *arg)
>>       if (copy_from_user(&flags, arg, sizeof(flags)))
>>           return -EFAULT;
>>
>> -    if (flags&  ~(FS_IMMUTABLE_FL | FS_APPEND_FL | \
>> -              FS_NOATIME_FL | FS_NODUMP_FL | \
>> -              FS_SYNC_FL | FS_DIRSYNC_FL))
>> -        return -EOPNOTSUPP;
>> +    ret =3D check_flags(flags);
>> +    if (ret)
>> +        return ret;
>>
>>       if (!is_owner_or_cap(inode))
>>           return -EACCES;
>> @@ -201,6 +218,22 @@ static int btrfs_ioctl_setflags(struct file
>> *file, void __user *arg)
>>       else
>>           ip->flags&=3D ~BTRFS_INODE_DIRSYNC;
>>
>> +    /*
>> +     * The COMPRESS flag can only be changed by users, while the
>> NOCOMPRESS
>> +     * flag may be changed automatically if compression code won't =
make
>> +     * things smaller.
>> +     */
>> +    if (flags&  FS_NOCOMP_FL) {
>> +        ip->flags&=3D ~BTRFS_INODE_COMPRESS;
>> +        ip->flags |=3D BTRFS_INODE_NOCOMPRESS;
>> +    } else if (flags&  FS_COMPR_FL) {
>> +        ip->flags |=3D BTRFS_INODE_COMPRESS;
>> +        ip->flags&=3D ~BTRFS_INODE_NOCOMPRESS;
>> +    }
>> +    if (flags&  FS_NOCOW_FL)
>> +        ip->flags |=3D BTRFS_INODE_NODATACOW;
>> +    else if (flags&  FS_COW_FL)
>> +        ip->flags&=3D ~BTRFS_INODE_NODATACOW;
>>
>>       trans =3D btrfs_join_transaction(root, 1);
>>       BUG_ON(IS_ERR(trans));
>=20
>=20

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