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* LVM2 tools/vgreduce.c ./WHATS_NEW lib/metadata ...
@ 2008-09-18 19:56 agk
0 siblings, 0 replies; only message in thread
From: agk @ 2008-09-18 19:56 UTC (permalink / raw)
To: lvm-devel, lvm2-cvs
CVSROOT: /cvs/lvm2
Module name: LVM2
Changes by: agk@sourceware.org 2008-09-18 19:56:50
Modified files:
tools : vgreduce.c
. : WHATS_NEW
lib/metadata : mirror.c metadata-exported.h
Log message:
Avoid shuffling remaining mirror images when removing one, retaining primary.
Patches:
http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/tools/vgreduce.c.diff?cvsroot=lvm2&r1=1.80&r2=1.81
http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/WHATS_NEW.diff?cvsroot=lvm2&r1=1.954&r2=1.955
http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/lib/metadata/mirror.c.diff?cvsroot=lvm2&r1=1.74&r2=1.75
http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/lib/metadata/metadata-exported.h.diff?cvsroot=lvm2&r1=1.50&r2=1.51
--- LVM2/tools/vgreduce.c 2008/04/08 12:49:21 1.80
+++ LVM2/tools/vgreduce.c 2008/09/18 19:56:50 1.81
@@ -250,9 +250,8 @@
lvl2->lv != seg_lv(mirrored_seg, s))
continue;
list_del(&lvl2->list);
- area = mirrored_seg->areas[mimages - 1];
- mirrored_seg->areas[mimages - 1] = mirrored_seg->areas[s];
- mirrored_seg->areas[s] = area;
+ if (!shift_mirror_images(mirrored_seg, s))
+ return_0;
mimages--; /* FIXME Assumes uniqueness */
}
}
--- LVM2/WHATS_NEW 2008/09/18 19:09:47 1.954
+++ LVM2/WHATS_NEW 2008/09/18 19:56:50 1.955
@@ -1,5 +1,6 @@
Version 2.02.40 -
================================
+ Avoid shuffling remaining mirror images when removing one, retaining primary.
Add missing LV error target activation in _remove_mirror_images.
Prevent resizing an LV while lvconvert is using it.
Avoid repeatedly wiping cache while VG_GLOBAL is held in vgscan & pvscan.
--- LVM2/lib/metadata/mirror.c 2008/09/18 19:09:47 1.74
+++ LVM2/lib/metadata/mirror.c 2008/09/18 19:56:50 1.75
@@ -136,6 +136,53 @@
}
/*
+ * shift_mirror_images
+ * @mirrored_seg
+ * @mimage: The position (index) of the image to move to the end
+ *
+ * When dealing with removal of legs, we often move a 'removable leg'
+ * to the back of the 'areas' array. It is critically important not
+ * to simply swap it for the last area in the array. This would have
+ * the affect of reordering the remaining legs - altering position of
+ * the primary. So, we must shuffle all of the areas in the array
+ * to maintain their relative position before moving the 'removable
+ * leg' to the end.
+ *
+ * Short illustration of the problem:
+ * - Mirror consists of legs A, B, C and we want to remove A
+ * - We swap A and C and then remove A, leaving C, B
+ * This scenario is problematic in failure cases where A dies, because
+ * B becomes the primary. If the above happens, we effectively throw
+ * away any changes made between the time of failure and the time of
+ * restructuring the mirror.
+ *
+ * So, any time we want to move areas to the end to be removed, use
+ * this function.
+ */
+int shift_mirror_images(struct lv_segment *mirrored_seg, unsigned mimage)
+{
+ int i;
+ struct lv_segment_area area;
+
+ if (mimage >= mirrored_seg->area_count) {
+ log_error("Invalid index (%u) of mirror image supplied "
+ "to shift_mirror_images()", mimage);
+ return 0;
+ }
+
+ area = mirrored_seg->areas[mimage];
+
+ /* Shift remaining images down to fill the hole */
+ for (i = mimage + 1; i < mirrored_seg->area_count; i++)
+ mirrored_seg->areas[i-1] = mirrored_seg->areas[i];
+
+ /* Place this one at the end */
+ mirrored_seg->areas[i-1] = area;
+
+ return 0;
+}
+
+/*
* This function writes a new header to the mirror log header to the lv
*
* Returns: 1 on success, 0 on failure
@@ -469,13 +516,12 @@
for (s = 0; s < mirrored_seg->area_count &&
old_area_count - new_area_count < num_removed; s++) {
sub_lv = seg_lv(mirrored_seg, s);
+
if (!is_temporary_mirror_layer(sub_lv) &&
_is_mirror_image_removable(sub_lv, removable_pvs)) {
- /* Swap segment to end */
+ if (!shift_mirror_images(mirrored_seg, s))
+ return_0;
new_area_count--;
- area = mirrored_seg->areas[new_area_count];
- mirrored_seg->areas[new_area_count] = mirrored_seg->areas[s];
- mirrored_seg->areas[s] = area;
}
}
if (num_removed && old_area_count == new_area_count)
--- LVM2/lib/metadata/metadata-exported.h 2008/08/05 12:05:25 1.50
+++ LVM2/lib/metadata/metadata-exported.h 2008/09/18 19:56:50 1.51
@@ -532,6 +532,7 @@
int reconfigure_mirror_images(struct lv_segment *mirrored_seg, uint32_t num_mirrors,
struct list *removable_pvs, unsigned remove_log);
int collapse_mirrored_lv(struct logical_volume *lv);
+int shift_mirror_images(struct lv_segment *mirrored_seg, unsigned mimage);
struct logical_volume *find_pvmove_lv(struct volume_group *vg,
struct device *dev, uint32_t lv_type);
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2008-09-18 19:56 LVM2 tools/vgreduce.c ./WHATS_NEW lib/metadata agk
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