src/extent-scan.h

   1 /* core functions for efficient reading sparse files
   2    Copyright (C) 2010-2012 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16
  17    Written by Jie Liu (jeff.liu@oracle.com).  */
  18
  19 #ifndef EXTENT_SCAN_H
  20 # define EXTENT_SCAN_H
  21
  22 /* Structure used to store information of each extent.  */
  23 struct extent_info
  24 {
  25   /* Logical offset of an extent.  */
  26   off_t ext_logical;
  27
  28   /* Extent length.  */
  29   uint64_t ext_length;
  30
  31   /* Extent flags, use it for FIEMAP only, or set it to zero.  */
  32   uint32_t ext_flags;
  33 };
  34
  35 /* Structure used to reserve extent scan information per file.  */
  36 struct extent_scan
  37 {
  38   /* File descriptor of extent scan run against.  */
  39   int fd;
  40
  41   /* Next scan start offset.  */
  42   off_t scan_start;
  43
  44   /* Flags to use for scan.  */
  45   uint32_t fm_flags;
  46
  47   /* How many extent info returned for a scan.  */
  48   uint32_t ei_count;
  49
  50   /* If true, fall back to a normal copy, either set by the
  51      failure of ioctl(2) for FIEMAP or lseek(2) with SEEK_DATA.  */
  52   bool initial_scan_failed;
  53
  54   /* If true, the total extent scan per file has been finished.  */
  55   bool hit_final_extent;
  56
  57   /* Extent information: a malloc'd array of ei_count structs.  */
  58   struct extent_info *ext_info;
  59 };
  60
  61 void extent_scan_init (int src_fd, struct extent_scan *scan);
  62
  63 bool extent_scan_read (struct extent_scan *scan);
  64
  65 static inline void
  66 extent_scan_free (struct extent_scan *scan)
  67 {
  68   free (scan->ext_info);
  69   scan->ext_info = NULL;
  70   scan->ei_count = 0;
  71 }
  72
  73 #endif /* EXTENT_SCAN_H */