Hi, Qu,
On 2015/09/08 17:56, Qu Wenruo wrote:
> Add new structures and functions for new qgroup reserve implement dirty
> phase.
> Which will focus on avoiding over-reserve as in that case, which means
> for already reserved dirty space range, we won't reserve space again.
>
> This patch adds the needed structure declaration and comments.
>
> Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
> ---
> fs/btrfs/btrfs_inode.h | 4 ++++
> fs/btrfs/qgroup.c | 58
> ++++++++++++++++++++++++++++++++++++++++++++++++++
> fs/btrfs/qgroup.h | 3 +++
> 3 files changed, 65 insertions(+)
>
> diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
> index 81220b2..e3ece65 100644
> --- a/fs/btrfs/btrfs_inode.h
> +++ b/fs/btrfs/btrfs_inode.h
> @@ -24,6 +24,7 @@
> #include "extent_io.h"
> #include "ordered-data.h"
> #include "delayed-inode.h"
> +#include "qgroup.h"
>
> /*
> * ordered_data_close is set by truncate when a file that used
> @@ -195,6 +196,9 @@ struct btrfs_inode {
> struct timespec i_otime;
>
> struct inode vfs_inode;
> +
> + /* qgroup dirty map for data space reserve */
> + struct btrfs_qgroup_data_rsv_map *qgroup_rsv_map;
> };
>
> extern unsigned char btrfs_filetype_table[];
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index e9ace09..561c36d 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -91,6 +91,64 @@ struct btrfs_qgroup {
> u64 new_refcnt;
> };
>
> +/*
> + * Record one range of reserved space.
> + */
> +struct data_rsv_range {
> + struct rb_node node;
> + u64 start;
> + u64 len;
> +};
> +
> +/*
> + * Record per inode reserved range.
> + * This is mainly used to resolve reserved space leaking problem.
> + * One of the cause is the mismatch with reserve and free.
> + *
> + * New qgroup will handle reserve in two phase.
> + * 1) Dirty phase.
> + * Pages are just marked dirty, but not written to disk.
> + * 2) Flushed phase
> + * Pages are written to disk, but transaction is not committed yet.
> + *
> + * At Diryt phase, we only need to focus on avoiding over-reserve.
dirty
> + *
> + * The idea is like below.
> + * 1) Write [0,8K)
> + * 0 4K 8K 12K 16K
> + * |////////////|
> + * Reserve +8K, total reserved: 8K
> + *
> + * 2) Write [0,4K)
> + * 0 4K 8K 12K 16K
> + * |////////////|
> + * Reserve 0, total reserved 8K
> + *
> + * 3) Write [12K,16K)
> + * 0 4K 8K 12K 16K
> + * |////////////| |///////|
> + * Reserve +4K, tocal reserved 12K
total
> + *
> + * 4) Flush [0,8K)
> + * Can happen without commit transaction, like fallocate will trigger the
> + * write.
> + * 0 4K 8K 12K 16K
> + * |///////|
> + * Reserve 0, tocal reserved 12K
total
Thanks,
Tsutomu
> + * As the extent is written to disk, not dirty any longer, the range get
> + * removed.
> + * But as its delayed_refs is not run, its reserved space will not be freed.
> + * And things continue to Flushed phase.
> + *
> + * By this method, we can avoid over-reserve, which will lead to reserved
> + * space leak.
> + */
> +struct btrfs_qgroup_data_rsv_map {
> + struct rb_root root;
> + u64 reserved;
> + spinlock_t lock;
> +};
> +
> static void btrfs_qgroup_update_old_refcnt(struct btrfs_qgroup *qg, u64 seq,
> int mod)
> {
> diff --git a/fs/btrfs/qgroup.h b/fs/btrfs/qgroup.h
> index 6387dcf..2f863a4 100644
> --- a/fs/btrfs/qgroup.h
> +++ b/fs/btrfs/qgroup.h
> @@ -33,6 +33,9 @@ struct btrfs_qgroup_extent_record {
> struct ulist *old_roots;
> };
>
> +/* For per-inode dirty range reserve */
> +struct btrfs_qgroup_data_rsv_map;
> +
> int btrfs_quota_enable(struct btrfs_trans_handle *trans,
> struct btrfs_fs_info *fs_info);
> int btrfs_quota_disable(struct btrfs_trans_handle *trans,
>
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