Re: [PATCH v15.1 01/13] btrfs: dedupe: Introduce dedupe framework and its header

[Timofey Titovets <nefelim4ag@gmail.com>]

вт, 6 нояб. 2018 г. в 9:41, Lu Fengqi <lufq.fnst@cn.fujitsu.com>:
>
> From: Wang Xiaoguang <wangxg.fnst@cn.fujitsu.com>
>
> Introduce the header for btrfs in-band(write time) de-duplication
> framework and needed header.
>
> The new de-duplication framework is going to support 2 different dedupe
> methods and 1 dedupe hash.
>
> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> Signed-off-by: Wang Xiaoguang <wangxg.fnst@cn.fujitsu.com>
> Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
> ---
>  fs/btrfs/ctree.h           |   7 ++
>  fs/btrfs/dedupe.h          | 128 ++++++++++++++++++++++++++++++++++++-
>  fs/btrfs/disk-io.c         |   1 +
>  include/uapi/linux/btrfs.h |  34 ++++++++++
>  4 files changed, 168 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 80953528572d..910050d904ef 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -1118,6 +1118,13 @@ struct btrfs_fs_info {
>         spinlock_t ref_verify_lock;
>         struct rb_root block_tree;
>  #endif
> +
> +       /*
> +        * Inband de-duplication related structures
> +        */
> +       unsigned long dedupe_enabled:1;
> +       struct btrfs_dedupe_info *dedupe_info;
> +       struct mutex dedupe_ioctl_lock;
>  };
>
>  static inline struct btrfs_fs_info *btrfs_sb(struct super_block *sb)
> diff --git a/fs/btrfs/dedupe.h b/fs/btrfs/dedupe.h
> index 90281a7a35a8..222ce7b4d827 100644
> --- a/fs/btrfs/dedupe.h
> +++ b/fs/btrfs/dedupe.h
> @@ -6,7 +6,131 @@
>  #ifndef BTRFS_DEDUPE_H
>  #define BTRFS_DEDUPE_H
>
> -/* later in-band dedupe will expand this struct */
> -struct btrfs_dedupe_hash;
> +#include <crypto/hash.h>
>
> +/* 32 bytes for SHA256 */
> +static const int btrfs_hash_sizes[] = { 32 };
> +
> +/*
> + * For caller outside of dedupe.c
> + *
> + * Different dedupe backends should have their own hash structure
> + */
> +struct btrfs_dedupe_hash {
> +       u64 bytenr;
> +       u32 num_bytes;
> +
> +       /* last field is a variable length array of dedupe hash */
> +       u8 hash[];
> +};
> +
> +struct btrfs_dedupe_info {
> +       /* dedupe blocksize */
> +       u64 blocksize;
> +       u16 backend;
> +       u16 hash_algo;
> +
> +       struct crypto_shash *dedupe_driver;
> +
> +       /*
> +        * Use mutex to portect both backends
> +        * Even for in-memory backends, the rb-tree can be quite large,
> +        * so mutex is better for such use case.
> +        */
> +       struct mutex lock;
> +
> +       /* following members are only used in in-memory backend */
> +       struct rb_root hash_root;
> +       struct rb_root bytenr_root;
> +       struct list_head lru_list;
> +       u64 limit_nr;
> +       u64 current_nr;
> +};
> +
> +static inline int btrfs_dedupe_hash_hit(struct btrfs_dedupe_hash *hash)
> +{
> +       return (hash && hash->bytenr);
> +}
> +
> +/*
> + * Initial inband dedupe info
> + * Called at dedupe enable time.
> + *
> + * Return 0 for success
> + * Return <0 for any error
> + * (from unsupported param to tree creation error for some backends)
> + */
> +int btrfs_dedupe_enable(struct btrfs_fs_info *fs_info,
> +                       struct btrfs_ioctl_dedupe_args *dargs);
> +
> +/*
> + * Disable dedupe and invalidate all its dedupe data.
> + * Called at dedupe disable time.
> + *
> + * Return 0 for success
> + * Return <0 for any error
> + * (tree operation error for some backends)
> + */
> +int btrfs_dedupe_disable(struct btrfs_fs_info *fs_info);
> +
> +/*
> + * Get current dedupe status.
> + * Return 0 for success
> + * No possible error yet
> + */
> +void btrfs_dedupe_status(struct btrfs_fs_info *fs_info,
> +                        struct btrfs_ioctl_dedupe_args *dargs);
> +
> +/*
> + * Calculate hash for dedupe.
> + * Caller must ensure [start, start + dedupe_bs) has valid data.
> + *
> + * Return 0 for success
> + * Return <0 for any error
> + * (error from hash codes)
> + */
> +int btrfs_dedupe_calc_hash(struct btrfs_fs_info *fs_info,
> +                          struct inode *inode, u64 start,
> +                          struct btrfs_dedupe_hash *hash);
> +
> +/*
> + * Search for duplicated extents by calculated hash
> + * Caller must call btrfs_dedupe_calc_hash() first to get the hash.
> + *
> + * @inode: the inode for we are writing
> + * @file_pos: offset inside the inode
> + * As we will increase extent ref immediately after a hash match,
> + * we need @file_pos and @inode in this case.
> + *
> + * Return > 0 for a hash match, and the extent ref will be
> + * *INCREASED*, and hash->bytenr/num_bytes will record the existing
> + * extent data.
> + * Return 0 for a hash miss. Nothing is done
> + * Return <0 for any error
> + * (tree operation error for some backends)
> + */
> +int btrfs_dedupe_search(struct btrfs_fs_info *fs_info,
> +                       struct inode *inode, u64 file_pos,
> +                       struct btrfs_dedupe_hash *hash);
> +
> +/*
> + * Add a dedupe hash into dedupe info
> + * Return 0 for success
> + * Return <0 for any error
> + * (tree operation error for some backends)
> + */
> +int btrfs_dedupe_add(struct btrfs_fs_info *fs_info,
> +                    struct btrfs_dedupe_hash *hash);
> +
> +/*
> + * Remove a dedupe hash from dedupe info
> + * Return 0 for success
> + * Return <0 for any error
> + * (tree operation error for some backends)
> + *
> + * NOTE: if hash deletion error is not handled well, it will lead
> + * to corrupted fs, as later dedupe write can points to non-exist or even
> + * wrong extent.
> + */
> +int btrfs_dedupe_del(struct btrfs_fs_info *fs_info, u64 bytenr);
>  #endif
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index b0ab41da91d1..d1fa9d90cc8f 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -2678,6 +2678,7 @@ int open_ctree(struct super_block *sb,
>         mutex_init(&fs_info->reloc_mutex);
>         mutex_init(&fs_info->delalloc_root_mutex);
>         mutex_init(&fs_info->cleaner_delayed_iput_mutex);
> +       mutex_init(&fs_info->dedupe_ioctl_lock);
>         seqlock_init(&fs_info->profiles_lock);
>
>         INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
> diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
> index 5ca1d21fc4a7..9cd15d2a40aa 100644
> --- a/include/uapi/linux/btrfs.h
> +++ b/include/uapi/linux/btrfs.h
> @@ -20,6 +20,7 @@
>  #ifndef _UAPI_LINUX_BTRFS_H
>  #define _UAPI_LINUX_BTRFS_H
>  #include <linux/types.h>
> +#include <linux/sizes.h>
>  #include <linux/ioctl.h>
>
>  #define BTRFS_IOCTL_MAGIC 0x94
> @@ -667,6 +668,39 @@ struct btrfs_ioctl_get_dev_stats {
>         __u64 unused[128 - 2 - BTRFS_DEV_STAT_VALUES_MAX]; /* pad to 1k */
>  };
>
> +/* In-band dedupe related */
> +#define BTRFS_DEDUPE_BACKEND_INMEMORY          0
> +#define BTRFS_DEDUPE_BACKEND_ONDISK            1
> +
> +/* Only support inmemory yet, so count is still only 1 */
> +#define BTRFS_DEDUPE_BACKEND_COUNT             1
> +
> +/* Dedup block size limit and default value */
> +#define BTRFS_DEDUPE_BLOCKSIZE_MAX     SZ_8M
> +#define BTRFS_DEDUPE_BLOCKSIZE_MIN     SZ_16K
> +#define BTRFS_DEDUPE_BLOCKSIZE_DEFAULT SZ_128K
> +
> +/* Hash algorithm, only support SHA256 yet */
> +#define BTRFS_DEDUPE_HASH_SHA256               0
> +
> +/*
> + * This structure is used for dedupe enable/disable/configure
> + * and status ioctl.
> + * Reserved range should be set to 0xff.
> + */
> +struct btrfs_ioctl_dedupe_args {
> +       __u16 cmd;              /* In: command */
> +       __u64 blocksize;        /* In/Out: blocksize */
> +       __u64 limit_nr;         /* In/Out: limit nr for inmem backend */
> +       __u64 limit_mem;        /* In/Out: limit mem for inmem backend */
> +       __u64 current_nr;       /* Out: current hash nr */
> +       __u16 backend;          /* In/Out: current backend */
> +       __u16 hash_algo;        /* In/Out: hash algorithm */
> +       u8 status;              /* Out: enabled or disabled */
> +       u8 flags;               /* In: special flags for ioctl */
> +       u8 __unused[472];       /* Pad to 512 bytes */
> +};
> +
>  #define BTRFS_QUOTA_CTL_ENABLE 1
>  #define BTRFS_QUOTA_CTL_DISABLE        2
>  #define BTRFS_QUOTA_CTL_RESCAN__NOTUSED        3
> --
> 2.19.1

Reviewed-by: Timofey Titovets <nefelim4ag@gmail.com>

Thanks.

-- 
Have a nice day,
Timofey.