mirror of
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323 lines
8.4 KiB
C
323 lines
8.4 KiB
C
/*
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* Copyright (C) 2002-2004 Sistina Software, Inc. All rights reserved.
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* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
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*
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* This file is part of LVM2.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU Lesser General Public License v.2.1.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "lib.h"
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#include "metadata.h"
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#include "locking.h"
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#include "toolcontext.h"
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#include "lv_alloc.h"
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#include "activate.h"
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int lv_is_origin(const struct logical_volume *lv)
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{
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return lv->origin_count ? 1 : 0;
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}
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int lv_is_cow(const struct logical_volume *lv)
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{
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/* Make sure a merging thin origin isn't confused as a cow LV */
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return (!lv_is_thin_volume(lv) && !lv_is_origin(lv) && lv->snapshot) ? 1 : 0;
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}
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static uint64_t _cow_max_size(uint64_t origin_size, uint32_t chunk_size)
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{
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/* Snapshot disk layout:
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* COW is divided into chunks
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* 1st. chunk is reserved for header
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* 2nd. chunk is the 1st. metadata chunk
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* 3rd. chunk is the 1st. data chunk
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*/
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/* Size of metadata for snapshot in sectors */
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uint64_t mdata_size = ((origin_size + chunk_size - 1) / chunk_size * 16 + 511) >> SECTOR_SHIFT;
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/* Sum all chunks - header + metadata size + origin size (aligned on chunk boundary) */
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uint64_t size = chunk_size +
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((mdata_size + chunk_size - 1) & ~(uint64_t)(chunk_size - 1)) +
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((origin_size + chunk_size - 1) & ~(uint64_t)(chunk_size - 1));
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/* Does not overflow since size is in sectors (9 bits) */
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return size;
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}
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uint32_t cow_max_extents(const struct logical_volume *origin, uint32_t chunk_size)
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{
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uint64_t size = _cow_max_size(origin->size, chunk_size);
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uint32_t extent_size = origin->vg->extent_size;
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uint64_t max_size = (uint64_t) MAX_EXTENT_COUNT * extent_size;
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if (size % extent_size)
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size += extent_size - size % extent_size;
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if (size > max_size)
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size = max_size; /* Origin is too big for 100% snapshot anyway */
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return (uint32_t) (size / extent_size);
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}
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int lv_is_cow_covering_origin(const struct logical_volume *lv)
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{
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return lv_is_cow(lv) &&
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(lv->size >= _cow_max_size(origin_from_cow(lv)->size, find_snapshot(lv)->chunk_size));
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}
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int lv_is_visible(const struct logical_volume *lv)
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{
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if (lv->status & SNAPSHOT)
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return 0;
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if (lv_is_cow(lv)) {
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if (lv_is_virtual_origin(origin_from_cow(lv)))
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return 1;
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if (lv_is_merging_cow(lv))
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return 0;
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return lv_is_visible(origin_from_cow(lv));
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}
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return lv->status & VISIBLE_LV ? 1 : 0;
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}
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int lv_is_virtual_origin(const struct logical_volume *lv)
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{
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return (lv->status & VIRTUAL_ORIGIN) ? 1 : 0;
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}
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int lv_is_merging_origin(const struct logical_volume *origin)
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{
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return (origin->status & MERGING) ? 1 : 0;
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}
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int lv_is_merging_cow(const struct logical_volume *snapshot)
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{
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/* checks lv_segment's status to see if cow is merging */
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return (find_snapshot(snapshot)->status & MERGING) ? 1 : 0;
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}
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struct lv_segment *find_snapshot(const struct logical_volume *lv)
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{
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return lv->snapshot;
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}
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/* Given a cow LV, return its origin */
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struct logical_volume *origin_from_cow(const struct logical_volume *lv)
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{
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if (lv->snapshot)
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return lv->snapshot->origin;
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return NULL;
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}
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void init_snapshot_seg(struct lv_segment *seg, struct logical_volume *origin,
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struct logical_volume *cow, uint32_t chunk_size, int merge)
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{
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seg->chunk_size = chunk_size;
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seg->origin = origin;
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seg->cow = cow;
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lv_set_hidden(cow);
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cow->snapshot = seg;
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origin->origin_count++;
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/* FIXME Assumes an invisible origin belongs to a sparse device */
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if (!lv_is_visible(origin))
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origin->status |= VIRTUAL_ORIGIN;
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seg->lv->status |= (SNAPSHOT | VIRTUAL);
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if (merge)
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init_snapshot_merge(seg, origin);
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dm_list_add(&origin->snapshot_segs, &seg->origin_list);
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}
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void init_snapshot_merge(struct lv_segment *snap_seg,
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struct logical_volume *origin)
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{
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snap_seg->status |= MERGING;
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origin->snapshot = snap_seg;
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origin->status |= MERGING;
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if (lv_is_thin_volume(origin)) {
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snap_seg->merge_lv = origin;
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/* Making thin LV inivisible with regular log */
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lv_set_hidden(snap_seg->lv);
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return;
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}
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/*
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* Even though lv_is_visible(snap_seg->lv) returns 0,
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* the snap_seg->lv (name: snapshotX) is _not_ hidden;
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* this is part of the lvm2 snapshot fiction. Must
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* clear VISIBLE_LV directly (lv_set_visible can't)
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* - snap_seg->lv->status is used to control whether 'lv'
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* (with user provided snapshot LV name) is visible
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* - this also enables vg_validate() to succeed with
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* merge metadata (snap_seg->lv is now "internal")
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*/
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snap_seg->lv->status &= ~VISIBLE_LV;
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}
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void clear_snapshot_merge(struct logical_volume *origin)
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{
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/* clear merge attributes */
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if (origin->snapshot->merge_lv)
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/* Removed thin volume has to be visible */
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lv_set_visible(origin->snapshot->lv);
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origin->snapshot->merge_lv = NULL;
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origin->snapshot->status &= ~MERGING;
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origin->snapshot = NULL;
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origin->status &= ~MERGING;
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}
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int vg_add_snapshot(struct logical_volume *origin,
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struct logical_volume *cow, union lvid *lvid,
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uint32_t extent_count, uint32_t chunk_size)
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{
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struct logical_volume *snap;
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struct lv_segment *seg;
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/*
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* Is the cow device already being used ?
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*/
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if (lv_is_cow(cow)) {
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log_error("'%s' is already in use as a snapshot.", cow->name);
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return 0;
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}
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if (cow == origin) {
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log_error("Snapshot and origin LVs must differ.");
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return 0;
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}
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if (!(snap = lv_create_empty("snapshot%d",
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lvid, LVM_READ | LVM_WRITE | VISIBLE_LV,
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ALLOC_INHERIT, origin->vg)))
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return_0;
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snap->le_count = extent_count;
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if (!(seg = alloc_snapshot_seg(snap, 0, 0)))
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return_0;
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init_snapshot_seg(seg, origin, cow, chunk_size, 0);
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return 1;
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}
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int vg_remove_snapshot(struct logical_volume *cow)
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{
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int merging_snapshot = 0;
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struct logical_volume *origin = origin_from_cow(cow);
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int is_origin_active = lv_is_active(origin);
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if (is_origin_active &&
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lv_is_virtual_origin(origin)) {
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if (!deactivate_lv(origin->vg->cmd, origin)) {
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log_error("Failed to deactivate logical volume \"%s\"",
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origin->name);
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return 0;
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}
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is_origin_active = 0;
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}
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dm_list_del(&cow->snapshot->origin_list);
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origin->origin_count--;
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if (lv_is_merging_origin(origin) &&
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(find_snapshot(origin) == find_snapshot(cow))) {
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clear_snapshot_merge(origin);
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/*
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* preload origin IFF "snapshot-merge" target is active
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* - IMPORTANT: avoids preload if onactivate merge is pending
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*/
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if (lv_has_target_type(origin->vg->cmd->mem, origin, NULL,
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"snapshot-merge")) {
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/*
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* preload origin to:
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* - allow proper release of -cow
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* - avoid allocations with other devices suspended
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* when transitioning from "snapshot-merge" to
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* "snapshot-origin after a merge completes.
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*/
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merging_snapshot = 1;
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}
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}
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if (!lv_remove(cow->snapshot->lv)) {
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log_error("Failed to remove internal snapshot LV %s",
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cow->snapshot->lv->name);
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return 0;
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}
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cow->snapshot = NULL;
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lv_set_visible(cow);
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/* format1 must do the change in one step, with the commit last. */
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if (!(origin->vg->fid->fmt->features & FMT_MDAS)) {
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/* Get the lock for COW volume */
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if (is_origin_active && !activate_lv(cow->vg->cmd, cow)) {
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log_error("Unable to activate logical volume \"%s\"",
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cow->name);
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return 0;
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}
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return 1;
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}
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if (!vg_write(origin->vg))
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return_0;
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/* Skip call suspend, if device is not active */
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if (is_origin_active && !suspend_lv(origin->vg->cmd, origin)) {
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log_error("Failed to refresh %s without snapshot.",
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origin->name);
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return 0;
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}
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if (!vg_commit(origin->vg))
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return_0;
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if (is_origin_active) {
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/*
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* If the snapshot was active and the COW LV is taken away
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* the LV lock on cluster has to be grabbed, so use
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* activate_lv() which resumes suspend cow device.
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*/
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if (!merging_snapshot && !activate_lv(cow->vg->cmd, cow)) {
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log_error("Failed to activate %s.", cow->name);
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return 0;
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}
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if (!resume_lv(origin->vg->cmd, origin)) {
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log_error("Failed to resume %s.", origin->name);
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return 0;
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}
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/*
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* For merged snapshot and clustered VG activate cow LV so
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* the following call to deactivate_lv() can clean-up table
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* entries. For this clustered lock need to be held.
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*/
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if (vg_is_clustered(cow->vg) &&
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merging_snapshot && !activate_lv(cow->vg->cmd, cow)) {
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log_error("Failed to activate %s.", cow->name);
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return 0;
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}
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}
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return 1;
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}
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