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a7c45ddc59
Previously, a command sent lvmetad new VG metadata in vg_commit().
In vg_commit(), devices are suspended, so any memory allocation
done by the command while sending to lvmetad, or by lvmetad while
updating its cache could deadlock if memory reclaim was triggered.
Now lvmetad is updated in unlock_vg(), after devices are resumed.
The new method for updating VG metadata in lvmetad is in two phases:
1. In vg_write(), before devices are suspended, the command sends
lvmetad a short message ("set_vg_info") telling it what the new
VG seqno will be. lvmetad sees that the seqno is newer than
the seqno of its cached VG, so it sets the INVALID flag for the
cached VG. If sending the message to lvmetad fails, the command
fails before the metadata is committed and the change is not made.
If sending the message succeeds, vg_commit() is called.
2. In unlock_vg(), after devices are resumed, the command sends
lvmetad the standard vg_update message with the new metadata.
lvmetad sees that the seqno in the new metadata matches the
seqno it saved from set_vg_info, and knows it has the latest
copy, so it clears the INVALID flag for the cached VG.
If a command fails between 1 and 2 (after committing the VG on disk,
but before sending lvmetad the new metadata), the cached VG retains
the INVALID flag in lvmetad. A subsequent command will read the
cached VG from lvmetad, see the INVALID flag, ignore the cached
copy, read the VG from disk instead, update the lvmetad copy
with the latest copy from disk, (this clears the INVALID flag
in lvmetad), and use the correct VG metadata for the command.
(This INVALID mechanism already existed for use by lvmlockd.)
114 lines
3.3 KiB
C
114 lines
3.3 KiB
C
/*
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* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
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* Copyright (C) 2004-2009 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "tools.h"
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#include "lvmetad-client.h"
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int vgcfgrestore(struct cmd_context *cmd, int argc, char **argv)
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{
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const char *vg_name = NULL;
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int lvmetad_rescan = 0;
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int ret;
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if (argc == 1) {
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vg_name = skip_dev_dir(cmd, argv[0], NULL);
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if (!validate_name(vg_name)) {
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log_error("Volume group name \"%s\" is invalid", vg_name);
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return EINVALID_CMD_LINE;
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}
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} else if (!(arg_is_set(cmd, list_ARG) && arg_is_set(cmd, file_ARG))) {
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log_error("Please specify a *single* volume group to restore.");
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return EINVALID_CMD_LINE;
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}
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/*
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* FIXME: overloading the -l arg for now to display a
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* list of archive files for a particular vg
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*/
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if (arg_is_set(cmd, list_ARG)) {
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if (!(arg_is_set(cmd,file_ARG) ?
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archive_display_file(cmd,
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arg_str_value(cmd, file_ARG, "")) :
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archive_display(cmd, vg_name)))
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return_ECMD_FAILED;
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return ECMD_PROCESSED;
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}
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/*
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* lvmetad does not handle a VG being restored, which would require
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* vg_remove of the existing VG, then vg_update of the restored VG. A
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* command failure after removing the existing VG from lvmetad would
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* not be easily recovered from. So, disable the lvmetad cache before
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* doing the restore. After the VG is restored on disk, rescan
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* metadata from disk to populate lvmetad from scratch which will pick
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* up the VG that was restored on disk.
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*/
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if (lvmetad_used()) {
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lvmetad_set_disabled(cmd, LVMETAD_DISABLE_REASON_VGRESTORE);
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lvmetad_disconnect();
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lvmetad_rescan = 1;
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}
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if (!lock_vol(cmd, vg_name, LCK_VG_WRITE, NULL)) {
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log_error("Unable to lock volume group %s", vg_name);
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return ECMD_FAILED;
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}
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if (!lock_vol(cmd, VG_ORPHANS, LCK_VG_WRITE, NULL)) {
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log_error("Unable to lock orphans");
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unlock_vg(cmd, NULL, vg_name);
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return ECMD_FAILED;
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}
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cmd->handles_unknown_segments = 1;
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if (!(arg_is_set(cmd, file_ARG) ?
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backup_restore_from_file(cmd, vg_name,
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arg_str_value(cmd, file_ARG, ""),
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arg_count(cmd, force_long_ARG)) :
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backup_restore(cmd, vg_name, arg_count(cmd, force_long_ARG)))) {
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unlock_vg(cmd, NULL, VG_ORPHANS);
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unlock_vg(cmd, NULL, vg_name);
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log_error("Restore failed.");
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ret = ECMD_FAILED;
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goto rescan;
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}
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ret = ECMD_PROCESSED;
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log_print_unless_silent("Restored volume group %s", vg_name);
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unlock_vg(cmd, NULL, VG_ORPHANS);
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unlock_vg(cmd, NULL, vg_name);
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rescan:
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if (lvmetad_rescan) {
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if (!lvmetad_connect(cmd)) {
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log_warn("WARNING: Failed to connect to lvmetad.");
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log_warn("WARNING: Update lvmetad with pvscan --cache.");
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goto out;
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}
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if (!refresh_filters(cmd))
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stack;
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if (!lvmetad_pvscan_all_devs(cmd, 1)) {
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log_warn("WARNING: Failed to scan devices.");
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log_warn("WARNING: Update lvmetad with pvscan --cache.");
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goto out;
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}
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}
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out:
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return ret;
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}
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