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Re: [PATCH 05/20] xfs: introduce rmap btree definitions

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH 05/20] xfs: introduce rmap btree definitions
From: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
Date: Tue, 2 Jun 2015 23:30:22 -0700
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1433311497-10245-6-git-send-email-david@xxxxxxxxxxxxx>
References: <1433311497-10245-1-git-send-email-david@xxxxxxxxxxxxx> <1433311497-10245-6-git-send-email-david@xxxxxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Wed, Jun 03, 2015 at 04:04:42PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
> 
> Add new per-ag rmap btree definitions to the per-ag structures. The
> rmap btree will sit inthe empty slots on disk after the free space
> btrees, and hence form a part of the array of space management
> btrees. This requires the definition of the btree to be contiguous
> with the free space btrees.
> 
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---
>  fs/xfs/libxfs/xfs_alloc.c  |  6 ++++++
>  fs/xfs/libxfs/xfs_btree.c  |  4 ++--
>  fs/xfs/libxfs/xfs_btree.h  |  3 +++
>  fs/xfs/libxfs/xfs_format.h | 22 +++++++++++++++++-----
>  fs/xfs/libxfs/xfs_types.h  |  4 ++--
>  5 files changed, 30 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index d4aa844..c7206b5 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -2267,6 +2267,10 @@ xfs_agf_verify(
>           be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNT]) > XFS_BTREE_MAXLEVELS)
>               return false;
>  
> +     if (xfs_sb_version_hasrmapbt(&mp->m_sb) &&
> +         be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAP]) > XFS_BTREE_MAXLEVELS)
> +             return false;
> +
>       /*
>        * during growfs operations, the perag is not fully initialised,
>        * so we can't use it for any useful checking. growfs ensures we can't
> @@ -2397,6 +2401,8 @@ xfs_alloc_read_agf(
>                       be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNOi]);
>               pag->pagf_levels[XFS_BTNUM_CNTi] =
>                       be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNTi]);
> +             pag->pagf_levels[XFS_BTNUM_RMAPi] =
> +                     be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAPi]);
>               spin_lock_init(&pag->pagb_lock);
>               pag->pagb_count = 0;
>               pag->pagb_tree = RB_ROOT;
> diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
> index c72283d..0426152 100644
> --- a/fs/xfs/libxfs/xfs_btree.c
> +++ b/fs/xfs/libxfs/xfs_btree.c
> @@ -42,9 +42,9 @@ kmem_zone_t *xfs_btree_cur_zone;
>   * Btree magic numbers.
>   */
>  static const __uint32_t xfs_magics[2][XFS_BTNUM_MAX] = {
> -     { XFS_ABTB_MAGIC, XFS_ABTC_MAGIC, XFS_BMAP_MAGIC, XFS_IBT_MAGIC,
> +     { XFS_ABTB_MAGIC, XFS_ABTC_MAGIC, 0, XFS_BMAP_MAGIC, XFS_IBT_MAGIC,
>         XFS_FIBT_MAGIC },
> -     { XFS_ABTB_CRC_MAGIC, XFS_ABTC_CRC_MAGIC,
> +     { XFS_ABTB_CRC_MAGIC, XFS_ABTC_CRC_MAGIC, XFS_RMAP_CRC_MAGIC,
>         XFS_BMAP_CRC_MAGIC, XFS_IBT_CRC_MAGIC, XFS_FIBT_CRC_MAGIC }
>  };
>  #define xfs_btree_magic(cur) \
> diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
> index 8f18bab..ace1995 100644
> --- a/fs/xfs/libxfs/xfs_btree.h
> +++ b/fs/xfs/libxfs/xfs_btree.h
> @@ -63,6 +63,7 @@ union xfs_btree_rec {
>  #define      XFS_BTNUM_BMAP  ((xfs_btnum_t)XFS_BTNUM_BMAPi)
>  #define      XFS_BTNUM_INO   ((xfs_btnum_t)XFS_BTNUM_INOi)
>  #define      XFS_BTNUM_FINO  ((xfs_btnum_t)XFS_BTNUM_FINOi)
> +#define      XFS_BTNUM_RMAP  ((xfs_btnum_t)XFS_BTNUM_RMAPi)
>  
>  /*
>   * For logging record fields.
> @@ -94,6 +95,7 @@ do {    \
>       case XFS_BTNUM_BMAP: __XFS_BTREE_STATS_INC(bmbt, stat); break;  \
>       case XFS_BTNUM_INO: __XFS_BTREE_STATS_INC(ibt, stat); break;    \
>       case XFS_BTNUM_FINO: __XFS_BTREE_STATS_INC(fibt, stat); break;  \
> +     case XFS_BTNUM_RMAP: break;     \

Hmm, so we don't have to provide stats for all the btrees?

<shrug> Actually, I thought it was rather clever that one could grep
/proc/fs/xfs/stat for 'rlbt' to find out if the running xfs driver supports
reflink.

(Not that I want someone to think this is some kind of ABI...)

>       case XFS_BTNUM_MAX: ASSERT(0); /* fucking gcc */ ; break;       \
>       }       \
>  } while (0)
> @@ -108,6 +110,7 @@ do {    \
>       case XFS_BTNUM_BMAP: __XFS_BTREE_STATS_ADD(bmbt, stat, val); break; \
>       case XFS_BTNUM_INO: __XFS_BTREE_STATS_ADD(ibt, stat, val); break; \
>       case XFS_BTNUM_FINO: __XFS_BTREE_STATS_ADD(fibt, stat, val); break; \
> +     case XFS_BTNUM_RMAP: break; \
>       case XFS_BTNUM_MAX: ASSERT(0); /* fucking gcc */ ; break;       \
>       }       \
>  } while (0)
> diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
> index a0ae572..d120af4 100644
> --- a/fs/xfs/libxfs/xfs_format.h
> +++ b/fs/xfs/libxfs/xfs_format.h
> @@ -445,6 +445,7 @@ xfs_sb_has_compat_feature(
>  }
>  
>  #define XFS_SB_FEAT_RO_COMPAT_FINOBT   (1 << 0)              /* free inode 
> btree */
> +#define XFS_SB_FEAT_RO_COMPAT_RMAPBT   (1 << 1)              /* reverse map 
> btree */
>  #define XFS_SB_FEAT_RO_COMPAT_ALL \
>               (XFS_SB_FEAT_RO_COMPAT_FINOBT)

... | XFS_SB_FEAT_RO_COMPAT_RMAPBT) ?

(/me shifts the reflink feature flag to (1 << 2))

>  #define XFS_SB_FEAT_RO_COMPAT_UNKNOWN        ~XFS_SB_FEAT_RO_COMPAT_ALL
> @@ -514,6 +515,12 @@ static inline bool xfs_sb_version_hassparseinodes(struct 
> xfs_sb *sbp)
>               xfs_sb_has_incompat_feature(sbp, XFS_SB_FEAT_INCOMPAT_SPINODES);
>  }
>  
> +static inline bool xfs_sb_version_hasrmapbt(struct xfs_sb *sbp)
> +{
> +     return (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5) &&
> +             (sbp->sb_features_ro_compat & XFS_SB_FEAT_RO_COMPAT_RMAPBT);
> +}
> +
>  /*
>   * end of superblock version macros
>   */
> @@ -574,10 +581,10 @@ xfs_is_quota_inode(struct xfs_sb *sbp, xfs_ino_t ino)
>  #define      XFS_AGI_GOOD_VERSION(v) ((v) == XFS_AGI_VERSION)
>  
>  /*
> - * Btree number 0 is bno, 1 is cnt.  This value gives the size of the
> + * Btree number 0 is bno, 1 is cnt, 2 is rmap. This value gives the size of 
> the
>   * arrays below.
>   */
> -#define      XFS_BTNUM_AGF   ((int)XFS_BTNUM_CNTi + 1)
> +#define      XFS_BTNUM_AGF   ((int)XFS_BTNUM_RMAPi + 1)
>  
>  /*
>   * The second word of agf_levels in the first a.g. overlaps the EFS
> @@ -594,12 +601,10 @@ typedef struct xfs_agf {
>       __be32          agf_seqno;      /* sequence # starting from 0 */
>       __be32          agf_length;     /* size in blocks of a.g. */
>       /*
> -      * Freespace information
> +      * Freespace and rmap information
>        */
>       __be32          agf_roots[XFS_BTNUM_AGF];       /* root blocks */
> -     __be32          agf_spare0;     /* spare field */
>       __be32          agf_levels[XFS_BTNUM_AGF];      /* btree levels */
> -     __be32          agf_spare1;     /* spare field */

Doh, field collision! :)

Guess I'll use up one of the agf_spare64's.

--D

>  
>       __be32          agf_flfirst;    /* first freelist block's index */
>       __be32          agf_fllast;     /* last freelist block's index */
> @@ -1277,6 +1282,13 @@ typedef __be32 xfs_inobt_ptr_t;
>  #define      XFS_FIBT_BLOCK(mp)              
> ((xfs_agblock_t)(XFS_IBT_BLOCK(mp) + 1))
>  
>  /*
> + * Reverse mapping btree format definitions
> + *
> + * There is a btree for the reverse map per allocation group
> + */
> +#define      XFS_RMAP_CRC_MAGIC      0x524d4233      /* 'RMB3' */
> +
> +/*
>   * The first data block of an AG depends on whether the filesystem was 
> formatted
>   * with the finobt feature. If so, account for the finobt reserved root btree
>   * block.
> diff --git a/fs/xfs/libxfs/xfs_types.h b/fs/xfs/libxfs/xfs_types.h
> index b79dc66..3d50364 100644
> --- a/fs/xfs/libxfs/xfs_types.h
> +++ b/fs/xfs/libxfs/xfs_types.h
> @@ -108,8 +108,8 @@ typedef enum {
>  } xfs_lookup_t;
>  
>  typedef enum {
> -     XFS_BTNUM_BNOi, XFS_BTNUM_CNTi, XFS_BTNUM_BMAPi, XFS_BTNUM_INOi,
> -     XFS_BTNUM_FINOi, XFS_BTNUM_MAX
> +     XFS_BTNUM_BNOi, XFS_BTNUM_CNTi, XFS_BTNUM_RMAPi, XFS_BTNUM_BMAPi,
> +     XFS_BTNUM_INOi, XFS_BTNUM_FINOi, XFS_BTNUM_MAX
>  } xfs_btnum_t;
>  
>  struct xfs_name {
> -- 
> 2.0.0
> 
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