From 488a58a9987fa578817f2d2144b45e00ac35d1e8 Mon Sep 17 00:00:00 2001
From: Joe Thornber <thornber@redhat.com>
Date: Thu, 29 Nov 2001 18:45:35 +0000
Subject: [PATCH] o  Striped allocator

o  Changed pv_map.c to maintain the list of free areas in size order, which
   is more helpful to the allocators.  If you want to allocate a bit of an
   area call consume_area(area, size), this will adjust the area if there's
   some space left and shuffle it to the correct place in the list.


Not tested.
---
 lib/metadata/lv_manip.c | 184 ++++++++++++++++++++++++++++++----------
 lib/metadata/pv_map.c   |  38 ++++++++-
 lib/metadata/pv_map.h   |   3 +
 3 files changed, 179 insertions(+), 46 deletions(-)

diff --git a/lib/metadata/lv_manip.c b/lib/metadata/lv_manip.c
index 6b3d1a357..336d4be4b 100644
--- a/lib/metadata/lv_manip.c
+++ b/lib/metadata/lv_manip.c
@@ -7,6 +7,7 @@
 #include "metadata.h"
 #include "pv_map.h"
 #include "log.h"
+#include "dbg_malloc.h"
 
 #include <assert.h>
 
@@ -40,6 +41,123 @@ static void _put_extents(struct stripe_segment *seg)
 	}
 }
 
+static struct stripe_segment *_alloc_segment(struct pool *mem, int stripes)
+{
+	struct stripe_segment *seg;
+	uint32_t len = sizeof(*seg) + (stripes * sizeof(seg->area[0]));
+
+	if (!(seg = pool_zalloc(mem, len))) {
+		stack;
+		return NULL;
+	}
+
+	return seg;
+}
+
+static int _alloc_stripe_area(struct logical_volume *lv, int stripes,
+			      struct pv_area **areas, uint32_t *index)
+{
+	uint32_t count = lv->le_count - *index;
+	uint32_t per_area = count / stripes;
+	uint32_t smallest = areas[stripes - 1]->count;
+	uint32_t s;
+	struct stripe_segment *seg;
+
+	if (smallest < per_area)
+		per_area = smallest;
+
+	if (!(seg = _alloc_segment(lv->vg->cmd->mem, stripes))) {
+		log_err("Couldn't allocate new stripe segment.");
+		return 0;
+	}
+
+	seg->lv = lv;
+	seg->le = *index;
+	seg->len = per_area * stripes;
+	seg->stripes = stripes;
+
+	for (s = 0; s < stripes; s++) {
+		struct pv_area *pva = areas[s];
+		seg->area[s].pv = pva->map->pv;
+		seg->area[s].pe = pva->start;
+		consume_pv_area(pva, per_area);
+	}
+
+	list_add(&lv->segments, &seg->list);
+	*index += seg->len;
+	return 1;
+}
+
+static int _comp_area(const void *l, const void *r)
+{
+	struct pv_area *lhs = *((struct pv_area **) l);
+	struct pv_area *rhs = *((struct pv_area **) r);
+
+	if (lhs->count < rhs->count)
+		return -1;
+
+	else if (lhs->count > rhs->count)
+		return 1;
+
+	return 0;
+}
+
+static int _alloc_striped(struct logical_volume *lv,
+			  struct list *pvms, uint32_t allocated,
+			  uint32_t stripes, uint32_t stripe_size)
+{
+	struct list *pvmh;
+	struct pv_area **areas;
+	int pv_count = 0, index;
+	struct pv_map *pvm;
+	size_t len;
+
+	list_iterate (pvmh, pvms)
+		pv_count++;
+
+	/* allocate an array of pv_areas, one candidate per pv */
+	len = sizeof(*areas) * pv_count;
+	if (!(areas = dbg_malloc(sizeof(*areas) * pv_count))) {
+		log_err("Couldn't allocate areas array.");
+		return 0;
+	}
+
+	while (allocated != lv->le_count) {
+
+		index = 0;
+		list_iterate (pvmh, pvms) {
+			pvm = list_item(pvmh, struct pv_map);
+
+			if (list_empty(&pvm->areas))
+				continue;
+
+			areas[index++] = list_item(pvm->areas.n,
+						   struct pv_area);
+		}
+
+		if (index < stripes)
+			goto no_space;
+
+		/* sort the areas so we allocate from the biggest */
+		qsort(areas, index, sizeof(*areas), _comp_area);
+
+		if (!_alloc_stripe_area(lv, stripes, areas, &allocated)) {
+			stack;
+			return 0;
+		}
+	}
+
+	return 1;
+
+ no_space:
+
+	log_error("Insufficient free extents (suitable for striping) to "
+		  "allocate logical volume %s: %u required",
+			  lv->name, lv->le_count);
+	return 0;
+}
+
+
 /*
  * The heart of the allocation code.  This
  * function takes a pv_area and allocates it to
@@ -48,32 +166,17 @@ static void _put_extents(struct stripe_segment *seg)
  * is unlinked from the pv_map.
  */
 static int _alloc_linear_area(struct logical_volume *lv, uint32_t *index,
-			      struct physical_volume *pv, struct pv_area *pva)
+			      struct pv_map *map, struct pv_area *pva)
 {
-	uint32_t count, remaining, start;
+	uint32_t count, remaining;
 	struct stripe_segment *seg;
 
-	start = pva->start;
-
 	count = pva->count;
 	remaining = lv->le_count - *index;
-
-	if (remaining < count) {
-		/* split the area */
+	if (count < remaining)
 		count = remaining;
-		pva->start += count;
-		pva->count -= count;
 
-	} else {
-		/* unlink the area */
-		list_del(&pva->list);
-	}
-
-	/* create the new segment */
-	seg = pool_zalloc(lv->vg->cmd->mem,
-			  sizeof(*seg) * sizeof(seg->area[0]));
-
-	if (!seg) {
+	if (!(seg = _alloc_segment(lv->vg->cmd->mem, 1))) {
 		log_err("Couldn't allocate new stripe segment.");
 		return 0;
 	}
@@ -83,51 +186,42 @@ static int _alloc_linear_area(struct logical_volume *lv, uint32_t *index,
 	seg->len = count;
 	seg->stripe_size = 0;
 	seg->stripes = 1;
-	seg->area[0].pv = pv;
-	seg->area[0].pe = start;
+	seg->area[0].pv = map->pv;
+	seg->area[0].pe = pva->start;
 
 	list_add(&lv->segments, &seg->list);
 
+	consume_pv_area(pva, count);
 	*index += count;
 	return 1;
 }
 
-static int _alloc_striped(struct logical_volume *lv,
-			  struct list *pvms, uint32_t allocated,
-			  uint32_t stripes, uint32_t stripe_size)
-{
-	/* FIXME: finish */
-	log_error("Striped allocation not implemented yet in LVM2.");
-	return 0;
-}
-
 /*
  * Only one area per pv is allowed, so we search
  * for the biggest area, or the first area that
  * can complete the allocation.
  */
+
+/*
+ * FIXME: subsequent lvextends may not be contiguous.
+ */
 static int _alloc_contiguous(struct logical_volume *lv,
 			     struct list *pvms, uint32_t allocated)
 {
-	struct list *tmp1, *tmp2;
+	struct list *tmp1;
 	struct pv_map *pvm;
-	struct pv_area *pva, *biggest;
+	struct pv_area *pva;
 
 	list_iterate(tmp1, pvms) {
 		pvm = list_item(tmp1, struct pv_map);
-		biggest = NULL;
 
-		list_iterate(tmp2, &pvm->areas) {
-			pva = list_item(tmp2, struct pv_area);
+		if (list_empty(&pvm->areas))
+			continue;
 
-			if (!biggest || (pva->count > biggest->count))
-				biggest = pva;
+		/* first item in the list is the biggest */
+		pva = list_item(pvm->areas.n, struct pv_area);
 
-			if (biggest->count >= (lv->le_count - allocated))
-				break;
-		}
-
-		if (!_alloc_linear_area(lv, &allocated, pvm->pv, pva)) {
+		if (!_alloc_linear_area(lv, &allocated, pvm, pva)) {
 			stack;
 			return 0;
 		}
@@ -162,13 +256,13 @@ static int _alloc_simple(struct logical_volume *lv,
 
 		list_iterate(tmp2, &pvm->areas) {
 			pva = list_item(tmp2, struct pv_area);
-			if (!_alloc_linear_area(lv,&allocated, pvm->pv, pva) ||
+			if (!_alloc_linear_area(lv, &allocated, pvm, pva) ||
 			    (allocated == lv->le_count))
 				goto done;
 		}
 	}
 
-      done:
+ done:
 	if (allocated != lv->le_count) {
 		log_error("Insufficient free logical extents to "
 			  "allocate logical volume %s: %u required",
@@ -176,7 +270,7 @@ static int _alloc_simple(struct logical_volume *lv,
 		return 0;
 	}
 
-	return 1;
+	return 0;
 }
 
 /*
diff --git a/lib/metadata/pv_map.c b/lib/metadata/pv_map.c
index 200a7d715..2075fdfed 100644
--- a/lib/metadata/pv_map.c
+++ b/lib/metadata/pv_map.c
@@ -103,6 +103,27 @@ static int _fill_bitsets(struct volume_group *vg, struct list *maps)
 	return r;
 }
 
+/*
+ * Areas are maintained in size order.
+ */
+static void _insert_area(struct list *head, struct pv_area *a)
+{
+	struct list *pvah;
+	struct pv_area *pva;
+
+	list_iterate (pvah, head) {
+		pva = list_item(pvah, struct pv_area);
+
+		if (pva->count < a->count)
+			break;
+	}
+
+	a->list.n = &pva->list;
+	a->list.p = pva->list.p;
+	pva->list.p->n = &a->list;
+	pva->list.p = &a->list;
+}
+
 static int _create_single_area(struct pool *mem, struct pv_map *pvm,
 			       uint32_t *extent)
 {
@@ -127,9 +148,10 @@ static int _create_single_area(struct pool *mem, struct pv_map *pvm,
 		return 0;
 	}
 
+	pva->map = pvm;
 	pva->start = b;
 	pva->count = e - b;
-	list_add(&pvm->areas, &pva->list);
+	_insert_area(&pvm->areas, pva);
 	*extent = e;
 
 	return 1;
@@ -200,3 +222,17 @@ struct list *create_pv_maps(struct pool *mem, struct volume_group *vg,
 	pool_free(mem, maps);
 	return NULL;
 }
+
+void consume_pv_area(struct pv_area *pva, uint32_t to_go)
+{
+	list_del(&pva->list);
+
+	assert(to_go <= pva->count);
+
+	if (to_go < pva->count) {
+		/* split the area */
+		pva->start += to_go;
+		pva->count -= to_go;
+		_insert_area(&pva->map->areas, pva);
+	}
+}
diff --git a/lib/metadata/pv_map.h b/lib/metadata/pv_map.h
index 5cfe2685d..86e0d7624 100644
--- a/lib/metadata/pv_map.h
+++ b/lib/metadata/pv_map.h
@@ -20,6 +20,7 @@
  */
 
 struct pv_area {
+	struct pv_map *map;
 	uint32_t start;
 	uint32_t count;
 
@@ -37,4 +38,6 @@ struct pv_map {
 struct list *create_pv_maps(struct pool *mem,
 			    struct volume_group *vg, struct list *pvs);
 
+void consume_pv_area(struct pv_area *area, uint32_t to_go);
+
 #endif