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?
>
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.
>
hmm, I'm making the tool's patch, and will come soon. :)
>
> On 21/3/2011 10:57 ÏÎ, 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 per
>> directory basis. This has been proposed previously, but VFS developers
>> wanted us to use generic ioctls rather than btrfs-specific ones.
>>
>> According to chris's comment, there should be just one true compression
>> 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 super.
>> 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@xxxxxxxxxxxxxx>
>> ---
>> 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. This
>> * 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 super
>> + * block, and it'll be used for per file compression control.
>> + */
>> + fs_info->compress_type = BTRFS_COMPRESS_ZLIB;
>> +
>> ret = btrfs_parse_options(tree_root, options);
>> if (ret) {
>> err = 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 = kzalloc(sizeof(struct page *) * nr_pages, GFP_NOFS);
>>
>> @@ -1253,7 +1254,8 @@ static int run_delalloc_range(struct inode
>> *inode, struct page *locked_page,
>> ret = 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 = 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 = 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 |= BTRFS_INODE_NODATASUM;
>> @@ -4590,6 +4590,8 @@ static struct inode *btrfs_new_inode(struct
>> btrfs_trans_handle *trans,
>> BTRFS_I(inode)->flags |= 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 flags
>> of the new
>> + * directory.
>> + */
>> +static void fixup_inode_flags(struct inode *dir, struct inode *inode)
>> +{
>> + struct btrfs_inode *b_dir = BTRFS_I(dir);
>> + struct btrfs_inode *b_inode = BTRFS_I(inode);
>> +
>> + if (b_dir->flags& BTRFS_INODE_NODATACOW)
>> + b_inode->flags |= BTRFS_INODE_NODATACOW;
>> + else
>> + b_inode->flags&= ~BTRFS_INODE_NODATACOW;
>> +
>> + if (b_dir->flags& BTRFS_INODE_COMPRESS)
>> + b_inode->flags |= BTRFS_INODE_COMPRESS;
>> + else
>> + b_inode->flags&= ~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 = 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 *arg)
>> {
>> struct inode *inode = 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 = 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&= ~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&= ~BTRFS_INODE_COMPRESS;
>> + ip->flags |= BTRFS_INODE_NOCOMPRESS;
>> + } else if (flags& FS_COMPR_FL) {
>> + ip->flags |= BTRFS_INODE_COMPRESS;
>> + ip->flags&= ~BTRFS_INODE_NOCOMPRESS;
>> + }
>> + if (flags& FS_NOCOW_FL)
>> + ip->flags |= BTRFS_INODE_NODATACOW;
>> + else if (flags& FS_COW_FL)
>> + ip->flags&= ~BTRFS_INODE_NODATACOW;
>>
>> trans = btrfs_join_transaction(root, 1);
>> BUG_ON(IS_ERR(trans));
>
>
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