lib/label/label.h

   1 /*
   2  * Copyright (C) 2002-2004 Sistina Software, Inc. All rights reserved.
   3  * Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
   4  *
   5  * This file is part of LVM2.
   6  *
   7  * This copyrighted material is made available to anyone wishing to use,
   8  * modify, copy, or redistribute it subject to the terms and conditions
   9  * of the GNU Lesser General Public License v.2.1.
  10  *
  11  * You should have received a copy of the GNU Lesser General Public License
  12  * along with this program; if not, write to the Free Software Foundation,
  13  * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  14  */
  15
  16 #ifndef _LVM_LABEL_H
  17 #define _LVM_LABEL_H
  18
  19 #include "uuid.h"
  20 #include "device.h"
  21
  22 #define LABEL_ID "LABELONE"
  23 #define LABEL_SIZE SECTOR_SIZE  /* Think very carefully before changing this */
  24 #define LABEL_SCAN_SECTORS 4L
  25 #define LABEL_SCAN_SIZE (LABEL_SCAN_SECTORS << SECTOR_SHIFT)
  26
  27 struct labeller;
  28
  29 void allow_reads_with_lvmetad(void);
  30
  31 /* On disk - 32 bytes */
  32 struct label_header {
  33         int8_t id[8];           /* LABELONE */
  34         uint64_t sector_xl;     /* Sector number of this label */
  35         uint32_t crc_xl;        /* From next field to end of sector */
  36         uint32_t offset_xl;     /* Offset from start of struct to contents */
  37         int8_t type[8];         /* LVM2 001 */
  38 } __attribute__ ((packed));
  39
  40 /* In core */
  41 struct label {
  42         char type[8];
  43         uint64_t sector;
  44         struct labeller *labeller;
  45         void *info;
  46 };
  47
  48 struct labeller;
  49
  50 struct label_ops {
  51         /*
  52          * Is the device labelled with this format ?
  53          */
  54         int (*can_handle) (struct labeller * l, void *buf, uint64_t sector);
  55
  56         /*
  57          * Write a label to a volume.
  58          */
  59         int (*write) (struct label * label, void *buf);
  60
  61         /*
  62          * Read a label from a volume.
  63          */
  64         int (*read) (struct labeller * l, struct device * dev,
  65                      void *buf, struct label ** label);
  66
  67         /*
  68          * Additional consistency checks for the paranoid.
  69          */
  70         int (*verify) (struct labeller * l, void *buf, uint64_t sector);
  71
  72         /*
  73          * Populate label_type etc.
  74          */
  75         int (*initialise_label) (struct labeller * l, struct label * label);
  76
  77         /*
  78          * Destroy a previously read label.
  79          */
  80         void (*destroy_label) (struct labeller * l, struct label * label);
  81
  82         /*
  83          * Destructor.
  84          */
  85         void (*destroy) (struct labeller * l);
  86 };
  87
  88 struct labeller {
  89         struct label_ops *ops;
  90         const void *private;
  91 };
  92
  93 int label_init(void);
  94 void label_exit(void);
  95
  96 int label_register_handler(const char *name, struct labeller *handler);
  97
  98 struct labeller *label_get_handler(const char *name);
  99
 100 int label_remove(struct device *dev);
 101 int label_read(struct device *dev, struct label **result,
 102                 uint64_t scan_sector);
 103 int label_write(struct device *dev, struct label *label);
 104 int label_verify(struct device *dev);
 105 struct label *label_create(struct labeller *labeller);
 106 void label_destroy(struct label *label);
 107
 108 #endif