[lvm-devel] master - lvmcache: fix duplicate handling with multiple scans
David Teigland
teigland at fedoraproject.org
Tue Jun 7 20:22:56 UTC 2016
Gitweb: http://git.fedorahosted.org/git/?p=lvm2.git;a=commitdiff;h=199b7b55c21270d62ce35f32b16df200417dc41c
Commit: 199b7b55c21270d62ce35f32b16df200417dc41c
Parent: 01156de6f70ba5b1c8e2ae23c655ccd36ac59441
Author: David Teigland <teigland at redhat.com>
AuthorDate: Mon Jun 6 15:20:55 2016 -0500
Committer: David Teigland <teigland at redhat.com>
CommitterDate: Tue Jun 7 15:15:51 2016 -0500
lvmcache: fix duplicate handling with multiple scans
Some commands scan labels to populate lvmcache multiple
times, i.e. lvmcache_init, scan labels to fill lvmcache,
lvmcache_destroy, then later repeat
Each time labels are scanned, duplicates are detected,
and preferred devices are chosen. Each time this is done
within a single command, we want to choose the same
preferred devices. So, check for existing preferences
when choosing preferred devices.
This also fixes a problem with the list of unused duplicate
devs when run in an lvm shell. The devs had been allocated
from cmd memory, resulting in invalid list entries between
commands.
---
lib/cache/lvmcache.c | 90 ++++++++++++++++++++++++++++++++++++++-----
lib/commands/toolcontext.c | 2 +
lib/commands/toolcontext.h | 1 +
3 files changed, 82 insertions(+), 11 deletions(-)
diff --git a/lib/cache/lvmcache.c b/lib/cache/lvmcache.c
index 1af6363..87b25f1 100644
--- a/lib/cache/lvmcache.c
+++ b/lib/cache/lvmcache.c
@@ -97,6 +97,8 @@ int lvmcache_init(void)
_vgs_locked = 0;
dm_list_init(&_vginfos);
+ dm_list_init(&_found_duplicate_devs);
+ dm_list_init(&_unused_duplicate_devs);
if (!(_vgname_hash = dm_hash_create(128)))
return 0;
@@ -471,6 +473,16 @@ void lvmcache_remove_unchosen_duplicate(struct device *dev)
}
}
+static void _destroy_duplicate_device_list(struct dm_list *head)
+{
+ struct device_list *devl, *devl2;
+
+ dm_list_iterate_items_safe(devl, devl2, head) {
+ dm_list_del(&devl->list);
+ dm_free(devl);
+ }
+ dm_list_init(head);
+}
static void _vginfo_attach_info(struct lvmcache_vginfo *vginfo,
struct lvmcache_info *info)
@@ -807,17 +819,22 @@ int vg_has_duplicate_pvs(struct volume_group *vg)
return 0;
}
-int lvmcache_dev_is_unchosen_duplicate(struct device *dev)
+static int _dev_in_device_list(struct device *dev, struct dm_list *head)
{
struct device_list *devl;
- dm_list_iterate_items(devl, &_unused_duplicate_devs) {
+ dm_list_iterate_items(devl, head) {
if (devl->dev == dev)
return 1;
}
return 0;
}
+int lvmcache_dev_is_unchosen_duplicate(struct device *dev)
+{
+ return _dev_in_device_list(dev, &_unused_duplicate_devs);
+}
+
/*
* Compare _found_duplicate_devs entries with the corresponding duplicate dev
* in lvmcache. There may be multiple duplicates in _found_duplicate_devs for
@@ -843,6 +860,7 @@ static void _choose_preferred_devs(struct cmd_context *cmd,
char uuid[64] __attribute__((aligned(8)));
const char *reason = "none";
struct dm_list altdevs;
+ struct dm_list new_unused;
struct dev_types *dt = cmd->dev_types;
struct device_list *devl, *devl_safe, *alt, *del;
struct lvmcache_info *info;
@@ -854,8 +872,11 @@ static void _choose_preferred_devs(struct cmd_context *cmd,
int has_fs1, has_fs2;
int has_lv1, has_lv2;
int same_size1, same_size2;
+ int prev_unchosen1, prev_unchosen2;
int change;
+ dm_list_init(&new_unused);
+
/*
* Create a list of all alternate devs for the same pvid: altdevs.
*/
@@ -873,8 +894,11 @@ next:
}
}
- if (!alt)
+ if (!alt) {
+ _destroy_duplicate_device_list(&_unused_duplicate_devs);
+ dm_list_splice(&_unused_duplicate_devs, &new_unused);
return;
+ }
/*
* Find the device for the pvid that's currently in lvmcache.
@@ -904,6 +928,21 @@ next:
continue;
}
+ prev_unchosen1 = _dev_in_device_list(dev1, &_unused_duplicate_devs);
+ prev_unchosen2 = _dev_in_device_list(dev2, &_unused_duplicate_devs);
+
+ if (!prev_unchosen1 && !prev_unchosen2) {
+ /*
+ * The cmd list saves the unchosen preference across
+ * lvmcache_destroy. Sometimes a single command will
+ * fill lvmcache, destroy it, and refill it, and we
+ * want the same duplicate preference to be preserved
+ * in each instance of lvmcache for a single command.
+ */
+ prev_unchosen1 = _dev_in_device_list(dev1, &cmd->unused_duplicate_devs);
+ prev_unchosen2 = _dev_in_device_list(dev2, &cmd->unused_duplicate_devs);
+ }
+
dev1_major = MAJOR(dev1->dev);
dev1_minor = MINOR(dev1->dev);
dev2_major = MAJOR(dev2->dev);
@@ -941,6 +980,11 @@ next:
dev_name(dev1), (unsigned long long)dev1_size,
dev_name(dev2), (unsigned long long)dev2_size);
+ log_debug_cache("PV %s: %s was prev %s. %s was prev %s.",
+ devl->dev->pvid,
+ dev_name(dev1), prev_unchosen1 ? "not chosen" : "<none>",
+ dev_name(dev2), prev_unchosen2 ? "not chosen" : "<none>");
+
log_debug_cache("PV %s: %s %s subsystem. %s %s subsystem.",
devl->dev->pvid,
dev_name(dev1), in_subsys1 ? "is in" : "is not in",
@@ -963,7 +1007,14 @@ next:
change = 0;
- if (has_lv1 && !has_lv2) {
+ if (prev_unchosen1 && !prev_unchosen2) {
+ /* change to 2 (NB when unchosen is set we unprefer) */
+ change = 1;
+ reason = "of previous preference";
+ } else if (prev_unchosen2 && !prev_unchosen1) {
+ /* keep 1 (NB when unchosen is set we unprefer) */
+ reason = "of previous preference";
+ } else if (has_lv1 && !has_lv2) {
/* keep 1 */
reason = "device is used by LV";
} else if (has_lv2 && !has_lv1) {
@@ -1023,7 +1074,7 @@ next:
dm_list_move(add_cache_devs, &alt->list);
- if ((del = dm_pool_alloc(cmd->mem, sizeof(*del)))) {
+ if ((del = dm_zalloc(sizeof(*del)))) {
del->dev = info->dev;
dm_list_add(del_cache_devs, &del->list);
}
@@ -1039,7 +1090,7 @@ next:
* duplicates not being used in lvmcache.
*/
- dm_list_splice(&_unused_duplicate_devs, &altdevs);
+ dm_list_splice(&new_unused, &altdevs);
goto next;
}
@@ -1087,6 +1138,11 @@ int lvmcache_label_scan(struct cmd_context *cmd)
log_very_verbose("Scanning device labels");
+ /*
+ * Duplicates found during this label scan are added to _found_duplicate_devs().
+ */
+ _destroy_duplicate_device_list(&_found_duplicate_devs);
+
while ((dev = dev_iter_get(iter))) {
(void) label_read(dev, &label, UINT64_C(0));
dev_count++;
@@ -2127,7 +2183,7 @@ struct lvmcache_info *lvmcache_add(struct labeller *labeller,
* use it.
*/
- if (!(devl = dm_pool_alloc(fmt->cmd->mem, sizeof(*devl))))
+ if (!(devl = dm_zalloc(sizeof(*devl))))
return_NULL;
devl->dev = dev;
@@ -2266,13 +2322,25 @@ void lvmcache_destroy(struct cmd_context *cmd, int retain_orphans, int reset)
log_error(INTERNAL_ERROR "_vginfos list should be empty");
dm_list_init(&_vginfos);
+ /*
+ * Copy the current _unused_duplicate_devs into a cmd list before
+ * destroying _unused_duplicate_devs.
+ *
+ * One command can init/populate/destroy lvmcache multiple times. Each
+ * time it will encounter duplicates and choose the preferrred devs.
+ * We want the same preferred devices to be chosen each time, so save
+ * the unpreferred devs here so that _choose_preferred_devs can use
+ * this to make the same choice each time.
+ */
+ dm_list_init(&cmd->unused_duplicate_devs);
+ lvmcache_get_unused_duplicate_devs(cmd, &cmd->unused_duplicate_devs);
+ _destroy_duplicate_device_list(&_unused_duplicate_devs);
+ _destroy_duplicate_device_list(&_found_duplicate_devs); /* should be empty anyway */
+ _found_duplicate_pvs = 0;
+
if (retain_orphans)
if (!init_lvmcache_orphans(cmd))
stack;
-
- dm_list_init(&_found_duplicate_devs);
- dm_list_init(&_unused_duplicate_devs);
- _found_duplicate_pvs = 0;
}
int lvmcache_pvid_is_locked(const char *pvid) {
diff --git a/lib/commands/toolcontext.c b/lib/commands/toolcontext.c
index 1e3f14a..076f48d 100644
--- a/lib/commands/toolcontext.c
+++ b/lib/commands/toolcontext.c
@@ -1977,6 +1977,8 @@ struct cmd_context *create_toolcontext(unsigned is_long_lived,
if (!init_lvmcache_orphans(cmd))
goto_out;
+ dm_list_init(&cmd->unused_duplicate_devs);
+
if (!_init_segtypes(cmd))
goto_out;
diff --git a/lib/commands/toolcontext.h b/lib/commands/toolcontext.h
index 2cecf27..f4beae1 100644
--- a/lib/commands/toolcontext.h
+++ b/lib/commands/toolcontext.h
@@ -197,6 +197,7 @@ struct cmd_context {
const char *report_list_item_separator;
const char *time_format;
unsigned rand_seed;
+ struct dm_list unused_duplicate_devs; /* save preferences between lvmcache instances */
};
/*
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