[lvm-devel] [PATCH v2] Fix readahead calculation segfault.
Milan Broz
mbroz at redhat.com
Sun May 31 20:43:45 UTC 2009
Fix readahead calculation problems.
During vgreduce is failed mirror image replaced with error segment,
this segmant type has always area_count == 0.
Current code expects that there is at least one area with device,
patch fixes it by additional check (fixes segfault during vgreduce).
Also do not calculate readahead in every lv_info call, we only need
to cache PV readahead before activation calls which locks memory.
Signed-off-by: Milan Broz <mbroz at redhat.com>
---
WHATS_NEW | 2 ++
lib/activate/activate.c | 11 ++++++-----
lib/activate/dev_manager.c | 2 +-
lib/metadata/metadata.c | 19 +++++++++++++------
lib/metadata/metadata.h | 2 +-
5 files changed, 23 insertions(+), 13 deletions(-)
diff --git a/WHATS_NEW b/WHATS_NEW
index c0840ca..4370530 100644
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,5 +1,7 @@
Version 2.02.48 -
===============================
+ Cache underlying device readahead only before activation calls.
+ Fix segfault when calculating readahead on missing device in vgreduce.
Remove verbose 'visited' messages.
Handle multi-extent mirror log allocation when smallest PV has only 1 extent.
Add LSB standard headers and functions (incl. reload) to clvmd initscript.
diff --git a/lib/activate/activate.c b/lib/activate/activate.c
index 12e8b20..aa75e5b 100644
--- a/lib/activate/activate.c
+++ b/lib/activate/activate.c
@@ -469,11 +469,6 @@ static int _lv_info(struct cmd_context *cmd, const struct logical_volume *lv, in
info->live_table = dminfo.live_table;
info->inactive_table = dminfo.inactive_table;
- /*
- * Cache read ahead value for PV devices now (before possible suspend)
- */
- (void)lv_calculate_readhead(lv);
-
if (name)
dm_pool_free(cmd->mem, name);
@@ -879,6 +874,8 @@ static int _lv_suspend(struct cmd_context *cmd, const char *lvid_s,
goto out;
}
+ lv_calculate_readahead(lv, NULL);
+
/* If VG was precommitted, preload devices for the LV */
if ((lv_pre->vg->status & PRECOMMITTED)) {
if (!_lv_preload(lv_pre, &flush_required)) {
@@ -1010,6 +1007,8 @@ int lv_deactivate(struct cmd_context *cmd, const char *lvid_s)
goto out;
}
+ lv_calculate_readahead(lv, NULL);
+
if (!monitor_dev_for_events(cmd, lv, 0))
stack;
@@ -1093,6 +1092,8 @@ static int _lv_activate(struct cmd_context *cmd, const char *lvid_s,
goto out;
}
+ lv_calculate_readahead(lv, NULL);
+
if (exclusive)
lv->status |= ACTIVATE_EXCL;
diff --git a/lib/activate/dev_manager.c b/lib/activate/dev_manager.c
index 5a932a6..ab61817 100644
--- a/lib/activate/dev_manager.c
+++ b/lib/activate/dev_manager.c
@@ -1023,7 +1023,7 @@ static int _add_new_lv_to_dtree(struct dev_manager *dm, struct dm_tree *dtree,
/* we need RA at least twice a whole stripe - see the comment in md/raid0.c */
read_ahead = max_stripe_size * 2;
if (!read_ahead)
- read_ahead = lv_calculate_readhead(lv);
+ lv_calculate_readahead(lv, &read_ahead);
read_ahead_flags = DM_READ_AHEAD_MINIMUM_FLAG;
}
diff --git a/lib/metadata/metadata.c b/lib/metadata/metadata.c
index 2b93bfb..1ee8e5d 100644
--- a/lib/metadata/metadata.c
+++ b/lib/metadata/metadata.c
@@ -1422,7 +1422,7 @@ static int _lv_read_ahead_single(struct logical_volume *lv, void *data)
struct lv_segment *seg = first_seg(lv);
uint32_t seg_read_ahead = 0, *read_ahead = data;
- if (seg && seg_type(seg, 0) == AREA_PV)
+ if (seg && seg->area_count && seg_type(seg, 0) == AREA_PV)
dev_get_read_ahead(seg_pv(seg, 0)->dev, &seg_read_ahead);
if (seg_read_ahead > *read_ahead)
@@ -1431,15 +1431,22 @@ static int _lv_read_ahead_single(struct logical_volume *lv, void *data)
return 1;
}
-uint32_t lv_calculate_readhead(const struct logical_volume *lv)
+/*
+ * Calculate readahead for logical volume from underlying PV devices.
+ * If read_ahead is NULL, only ensure that readahead of PVs are preloaded
+ * into PV struct device in dev cache.
+ */
+void lv_calculate_readahead(const struct logical_volume *lv, uint32_t *read_ahead)
{
- uint32_t read_ahead = 0;
+ uint32_t _read_ahead = 0;
if (lv->read_ahead == DM_READ_AHEAD_AUTO)
- _lv_postorder((struct logical_volume *)lv, _lv_read_ahead_single, &read_ahead);
+ _lv_postorder((struct logical_volume *)lv, _lv_read_ahead_single, &_read_ahead);
- log_debug("Calculated readahead of LV %s is %u", lv->name, read_ahead);
- return read_ahead;
+ if (read_ahead) {
+ log_debug("Calculated readahead of LV %s is %u", lv->name, _read_ahead);
+ *read_ahead = _read_ahead;
+ }
}
int vg_validate(struct volume_group *vg)
diff --git a/lib/metadata/metadata.h b/lib/metadata/metadata.h
index 380e639..ceb089c 100644
--- a/lib/metadata/metadata.h
+++ b/lib/metadata/metadata.h
@@ -347,7 +347,7 @@ unsigned snapshot_count(const struct volume_group *vg);
/*
* Calculate readahead from underlying PV devices
*/
-uint32_t lv_calculate_readhead(const struct logical_volume *lv);
+void lv_calculate_readahead(const struct logical_volume *lv, uint32_t *read_ahead);
/*
* For internal metadata caching.
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