src/patches/suse-2.6.27.39/patches.suse/ocfs2-Comment-struct-ocfs2_extent_tree_operations.patch

   1 From: Joel Becker <joel.becker@oracle.com>
   2 Subject: ocfs2: Comment struct ocfs2_extent_tree_operations.
   3 Patch-mainline: 2.6.28?
   4 References: FATE302067
   5
   6 struct ocfs2_extent_tree_operations provides methods for the different
   7 on-disk btrees in ocfs2.  Describing what those methods do is probably a
   8 good idea.
   9
  10 Signed-off-by: Joel Becker <joel.becker@oracle.com>
  11 Acked-by: Mark Fasheh <mark.fasheh@suse.com>
  12 ---
  13  fs/ocfs2/alloc.c |   45 +++++++++++++++++++++++++++++++++++++++++++--
  14  1 file changed, 43 insertions(+), 2 deletions(-)
  15
  16 --- a/fs/ocfs2/alloc.c
  17 +++ b/fs/ocfs2/alloc.c
  18 @@ -50,21 +50,62 @@
  19  #include "buffer_head_io.h"
  20
  21
  22 +/*
  23 + * Operations for a specific extent tree type.
  24 + *
  25 + * To implement an on-disk btree (extent tree) type in ocfs2, add
  26 + * an ocfs2_extent_tree_operations structure and the matching
  27 + * ocfs2_get_<thingy>_extent_tree() function.  That's pretty much it
  28 + * for the allocation portion of the extent tree.
  29 + */
  30  struct ocfs2_extent_tree_operations {
  31 +       /*
  32 +        * last_eb_blk is the block number of the right most leaf extent
  33 +        * block.  Most on-disk structures containing an extent tree store
  34 +        * this value for fast access.  The ->eo_set_last_eb_blk() and
  35 +        * ->eo_get_last_eb_blk() operations access this value.  They are
  36 +        *  both required.
  37 +        */
  38         void (*eo_set_last_eb_blk)(struct ocfs2_extent_tree *et,
  39                                    u64 blkno);
  40         u64 (*eo_get_last_eb_blk)(struct ocfs2_extent_tree *et);
  41 +
  42 +       /*
  43 +        * The on-disk structure usually keeps track of how many total
  44 +        * clusters are stored in this extent tree.  This function updates
  45 +        * that value.  new_clusters is the delta, and must be
  46 +        * added to the total.  Required.
  47 +        */
  48         void (*eo_update_clusters)(struct inode *inode,
  49                                    struct ocfs2_extent_tree *et,
  50                                    u32 new_clusters);
  51 +
  52 +       /*
  53 +        * If ->eo_insert_check() exists, it is called before rec is
  54 +        * inserted into the extent tree.  It is optional.
  55 +        */
  56         int (*eo_insert_check)(struct inode *inode,
  57                                struct ocfs2_extent_tree *et,
  58                                struct ocfs2_extent_rec *rec);
  59         int (*eo_sanity_check)(struct inode *inode, struct ocfs2_extent_tree *et);
  60
  61 -       /* These are internal to ocfs2_extent_tree and don't have
  62 -        * accessor functions */
  63 +       /*
  64 +        * --------------------------------------------------------------
  65 +        * The remaining are internal to ocfs2_extent_tree and don't have
  66 +        * accessor functions
  67 +        */
  68 +
  69 +       /*
  70 +        * ->eo_fill_root_el() takes et->et_object and sets et->et_root_el.
  71 +        * It is required.
  72 +        */
  73         void (*eo_fill_root_el)(struct ocfs2_extent_tree *et);
  74 +
  75 +       /*
  76 +        * ->eo_fill_max_leaf_clusters sets et->et_max_leaf_clusters if
  77 +        * it exists.  If it does not, et->et_max_leaf_clusters is set
  78 +        * to 0 (unlimited).  Optional.
  79 +        */
  80         void (*eo_fill_max_leaf_clusters)(struct inode *inode,
  81                                           struct ocfs2_extent_tree *et);
  82  };