/* $NetBSD: dm_target_snapshot.c,v 1.12 2010/01/04 00:12:22 haad Exp $ */ /* * Copyright (c) 2008 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Adam Hamsik. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * 1. Suspend my_data to temporarily stop any I/O while the snapshot is being * activated. * dmsetup suspend my_data * * 2. Create the snapshot-origin device with no table. * dmsetup create my_data_org * * 3. Read the table from my_data and load it into my_data_org. * dmsetup table my_data | dmsetup load my_data_org * * 4. Resume this new table. * dmsetup resume my_data_org * * 5. Create the snapshot device with no table. * dmsetup create my_data_snap * * 6. Load the table into my_data_snap. This uses /dev/hdd1 as the COW device and * uses a 32kB chunk-size. * echo "0 `blockdev --getsize /dev/mapper/my_data` snapshot \ * /dev/mapper/my_data_org /dev/hdd1 p 64" | dmsetup load my_data_snap * * 7. Reload my_data as a snapshot-origin device that points to my_data_org. * echo "0 `blockdev --getsize /dev/mapper/my_data` snapshot-origin \ * /dev/mapper/my_data_org" | dmsetup load my_data * * 8. Resume the snapshot and origin devices. * dmsetup resume my_data_snap * dmsetup resume my_data * * Before snapshot creation * dev_name; dev table * | my_data; 0 1024 linear /dev/sd1a 384| * * After snapshot creation * |my_data_org;0 1024 linear /dev/sd1a 384| * / * |my_data; 0 1024 snapshot-origin /dev/vg00/my_data_org| * / * |my_data_snap; 0 1024 snapshot /dev/vg00/my_data /dev/mapper/my_data_cow P 8 * \ * |my_data_cow; 0 256 linear /dev/sd1a 1408| */ /* * This file implements initial version of device-mapper snapshot target. */ #include <sys/kmem.h> #include <dev/disk/dm/dm.h> typedef struct target_snapshot_config { dm_pdev_t *tsc_snap_dev; /* cow dev is set only for persistent snapshot devices */ dm_pdev_t *tsc_cow_dev; uint64_t tsc_chunk_size; uint32_t tsc_persistent_dev; } dm_target_snapshot_config_t; typedef struct target_snapshot_origin_config { dm_pdev_t *tsoc_real_dev; /* list of snapshots ? */ } dm_target_snapshot_origin_config_t; int dm_target_snapshot_init(dm_table_entry_t *, int, char **); char *dm_target_snapshot_table(void *); int dm_target_snapshot_strategy(dm_table_entry_t *, struct buf *); int dm_target_snapshot_destroy(dm_table_entry_t *); int dm_target_snapshot_orig_init(dm_table_entry_t *, int, char **); char *dm_target_snapshot_orig_table(void *); int dm_target_snapshot_orig_strategy(dm_table_entry_t *, struct buf *); int dm_target_snapshot_orig_destroy(dm_table_entry_t *); /* * Init function called from dm_table_load_ioctl. * argv: /dev/mapper/my_data_org /dev/mapper/tsc_cow_dev p 64 * snapshot_origin device, cow device, persistent flag, chunk size */ int dm_target_snapshot_init(dm_table_entry_t *table_en, int argc, char **argv) { dm_target_snapshot_config_t *tsc; dm_pdev_t *dmp_snap, *dmp_cow; dmp_cow = NULL; kprintf("Snapshot target init function called!!\n"); kprintf("Snapshotted device: %s, cow device %s,\n\t persistent flag: %s, " "chunk size: %s\n", argv[0], argv[1], argv[2], argv[3]); /* Insert snap device to global pdev list */ if ((dmp_snap = dm_pdev_insert(argv[0])) == NULL) return ENOENT; tsc = kmem_alloc(sizeof(dm_target_snapshot_config_t), VM_SUBSYS_DM, KM_NOSLEEP); if (tsc == NULL) return 1; tsc->tsc_persistent_dev = 0; /* There is now cow device for nonpersistent snapshot devices */ if (strcmp(argv[2], "p") == 0) { tsc->tsc_persistent_dev = 1; /* Insert cow device to global pdev list */ if ((dmp_cow = dm_pdev_insert(argv[1])) == NULL) return ENOENT; } tsc->tsc_chunk_size = atoi64(argv[3]); tsc->tsc_snap_dev = dmp_snap; tsc->tsc_cow_dev = dmp_cow; dm_table_add_deps(table_en, dmp_snap); dm_table_add_deps(table_en, dmp_cow); dm_table_init_target(table_en, tsc); return 0; } /* * Table routine is called to get params string, which is target * specific. When dm_table_status_ioctl is called with flag * DM_STATUS_TABLE_FLAG I have to sent params string back. */ char * dm_target_snapshot_table(void *target_config) { dm_target_snapshot_config_t *tsc; uint32_t i; uint32_t count; size_t prm_len, cow_len; char *params, *cow_name; tsc = target_config; prm_len = 0; cow_len = 0; count = 0; cow_name = NULL; kprintf("Snapshot target table function called\n"); /* count number of chars in offset */ for (i = tsc->tsc_chunk_size; i != 0; i /= 10) count++; if (tsc->tsc_persistent_dev) cow_len = strlen(tsc->tsc_cow_dev->name); /* length of names + count of chars + spaces and null char */ prm_len = strlen(tsc->tsc_snap_dev->name) + cow_len + count + 5; params = dm_alloc_string(prm_len); kprintf("%s %s %s %" PRIu64 "\n", tsc->tsc_snap_dev->name, tsc->tsc_cow_dev->name, tsc->tsc_persistent_dev ? "p" : "n", tsc->tsc_chunk_size); ksnprintf(params, prm_len, "%s %s %s %" PRIu64, tsc->tsc_snap_dev->name, tsc->tsc_persistent_dev ? tsc->tsc_cow_dev->name : "", tsc->tsc_persistent_dev ? "p" : "n", tsc->tsc_chunk_size); return params; } /* Strategy routine called from dm_strategy. */ int dm_target_snapshot_strategy(dm_table_entry_t *table_en, struct buf *bp) { kprintf("Snapshot target read function called!!\n"); bp->b_error = EIO; bp->b_resid = 0; biodone(bp); return 0; } /* Doesn't do anything here. */ int dm_target_snapshot_destroy(dm_table_entry_t *table_en) { dm_target_snapshot_config_t *tsc; /* * Destroy function is called for every target even if it * doesn't have target_config. */ if (table_en->target_config == NULL) return 0; kprintf("Snapshot target destroy function called\n"); tsc = table_en->target_config; /* Decrement pdev ref counter if 0 remove it */ dm_pdev_decr(tsc->tsc_snap_dev); if (tsc->tsc_persistent_dev) dm_pdev_decr(tsc->tsc_cow_dev); kmem_free(table_en->target_config, sizeof(dm_target_snapshot_config_t)); return 0; } /* * dm target snapshot origin routines. * * Keep for compatibility with linux lvm2tools. They use two targets * to implement snapshots. Snapshot target will implement exception * store and snapshot origin will implement device which calls every * snapshot device when write is done on master device. */ /* * Init function called from dm_table_load_ioctl. * * argv: /dev/mapper/my_data_real */ int dm_target_snapshot_orig_init(dm_table_entry_t *table_en, int argc, char **argv) { dm_target_snapshot_origin_config_t *tsoc; dm_pdev_t *dmp_real; kprintf("Snapshot origin target init function called!!\n"); kprintf("Parent device: %s\n", argv[0]); /* Insert snap device to global pdev list */ if ((dmp_real = dm_pdev_insert(argv[0])) == NULL) return ENOENT; tsoc = kmem_alloc(sizeof(dm_target_snapshot_origin_config_t), VM_SUBSYS_DM, KM_NOSLEEP); if (tsoc == NULL) return 1; tsoc->tsoc_real_dev = dmp_real; dm_table_add_deps(table_en, dmp_real); dm_table_init_target(table_en, tsoc); return 0; } /* * Table routine is called to get params string, which is target * specific. When dm_table_status_ioctl is called with flag * DM_STATUS_TABLE_FLAG I have to sent params string back. */ char * dm_target_snapshot_orig_table(void *target_config) { dm_target_snapshot_origin_config_t *tsoc; size_t prm_len; char *params; tsoc = target_config; prm_len = 0; kprintf("Snapshot origin target table function called\n"); /* length of names + count of chars + spaces and null char */ prm_len = strlen(tsoc->tsoc_real_dev->name) + 1; kprintf("real_dev name %s\n", tsoc->tsoc_real_dev->name); params = kmem_alloc(prm_len, VM_SUBSYS_DM, KM_NOSLEEP); if (params == NULL) return NULL; kprintf("%s\n", tsoc->tsoc_real_dev->name); snprintf(params, prm_len, "%s", tsoc->tsoc_real_dev->name); return params; } /* Strategy routine called from dm_strategy. */ int dm_target_snapshot_orig_strategy(dm_table_entry_t *table_en, struct buf *bp) { kprintf("Snapshot_Orig target read function called!!\n"); bp->b_error = EIO; bp->b_resid = 0; biodone(bp); return 0; } /* Decrement pdev and free allocated space. */ int dm_target_snapshot_orig_destroy(dm_table_entry_t *table_en) { dm_target_snapshot_origin_config_t *tsoc; /* * Destroy function is called for every target even if it * doesn't have target_config. */ if (table_en->target_config == NULL) return 0; tsoc = table_en->target_config; /* Decrement pdev ref counter if 0 remove it */ dm_pdev_decr(tsoc->tsoc_real_dev); /* Unbusy target so we can unload it */ dm_target_unbusy(table_en->target); kmem_free(table_en->target_config, sizeof(dm_target_snapshot_origin_config_t)); return 0; }
