lustre/snapfs/journal_ext3.c

   1
   2 /*
   3  * Snapfs. (C) 2000 Peter J. Braam
   4  */
   5
   6 #define DEBUG_SUBSYSTEM S_SNAP
   7
   8 #include <linux/module.h>
   9 #include <linux/kernel.h>
  10 #include <linux/string.h>
  11 #include <linux/slab.h>
  12 #include <linux/stat.h>
  13 #include <linux/unistd.h>
  14 #include <linux/jbd.h>
  15 #include <linux/ext3_jbd.h>
  16 #include <linux/ext3_fs.h>
  17 #include <linux/snap.h>
  18
  19 #include "snapfs_internal.h"
  20
  21
  22 #define EXT3_EA_TRANS_BLOCKS EXT3_DATA_TRANS_BLOCKS
  23
  24 /*
  25  * must follow the changes of ext3_create_indirect() in fs/ext3/snap.c
  26  */
  27 #define COW_CREDITS (2 * EXT3_EA_TRANS_BLOCKS + 17 + 2 * EXT3_DATA_TRANS_BLOCKS )
  28
  29 /* start the filesystem journal operations */
  30 static void *snap_e3_trans_start(struct inode *inode, int op)
  31 {
  32         int jblocks;
  33
  34         /* XXX needs to be fixed up when we get reiserfs support */
  35         switch (op) {
  36         case SNAP_OP_CREATE:
  37                 jblocks = COW_CREDITS + EXT3_DATA_TRANS_BLOCKS + 3;
  38                 break;
  39         case SNAP_OP_LINK:
  40                 jblocks = COW_CREDITS + EXT3_DATA_TRANS_BLOCKS;
  41                 break;
  42         case SNAP_OP_UNLINK:
  43                 jblocks = COW_CREDITS + EXT3_DELETE_TRANS_BLOCKS;
  44                 break;
  45         case SNAP_OP_SYMLINK:
  46                 jblocks = COW_CREDITS + EXT3_DATA_TRANS_BLOCKS + 5;
  47                 break;
  48         case SNAP_OP_MKDIR:
  49                 jblocks = COW_CREDITS + EXT3_DATA_TRANS_BLOCKS + 4;
  50                 break;
  51         case SNAP_OP_RMDIR:
  52                 jblocks = 2 * COW_CREDITS + EXT3_DELETE_TRANS_BLOCKS;
  53                 break;
  54         case SNAP_OP_MKNOD:
  55                 jblocks = COW_CREDITS + EXT3_DATA_TRANS_BLOCKS + 3;
  56                 break;
  57         case SNAP_OP_RENAME:
  58                 jblocks = 4 * COW_CREDITS + 2 * EXT3_DATA_TRANS_BLOCKS + 2;
  59                 break;
  60         default:
  61                 CDEBUG(D_INODE, "invalid operation %d for journal\n", op);
  62                 return NULL;
  63         }
  64
  65         CDEBUG(D_INODE, "creating journal handle (%d blocks)\n", jblocks);
  66         return ext3_journal_start(inode, jblocks);
  67 }
  68
  69 static void snap_e3_trans_commit(void *handle)
  70 {
  71         journal_stop(handle);
  72 }
  73
  74 struct journal_ops snap_ext3_journal_ops = {
  75         snap_e3_trans_start,
  76         snap_e3_trans_commit
  77 };
  78