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-rw-r--r--meta/recipes-bsp/grub/files/0002-lvm-Add-LVM-cache-logical-volume-handling.patch287
1 files changed, 287 insertions, 0 deletions
diff --git a/meta/recipes-bsp/grub/files/0002-lvm-Add-LVM-cache-logical-volume-handling.patch b/meta/recipes-bsp/grub/files/0002-lvm-Add-LVM-cache-logical-volume-handling.patch
new file mode 100644
index 0000000000..2b8157f592
--- /dev/null
+++ b/meta/recipes-bsp/grub/files/0002-lvm-Add-LVM-cache-logical-volume-handling.patch
@@ -0,0 +1,287 @@
+From 8eb02bcb5897b238b29ff762402bb0c3028f0eab Mon Sep 17 00:00:00 2001
+From: Michael Chang <mchang@suse.com>
+Date: Thu, 19 Mar 2020 13:56:13 +0800
+Subject: [PATCH 3/9] lvm: Add LVM cache logical volume handling
+
+The LVM cache logical volume is the logical volume consisting of the original
+and the cache pool logical volume. The original is usually on a larger and
+slower storage device while the cache pool is on a smaller and faster one. The
+performance of the original volume can be improved by storing the frequently
+used data on the cache pool to utilize the greater performance of faster
+device.
+
+The default cache mode "writethrough" ensures that any data written will be
+stored both in the cache and on the origin LV, therefore grub can be straight
+to read the original lv as no data loss is guarenteed.
+
+The second cache mode is "writeback", which delays writing from the cache pool
+back to the origin LV to have increased performance. The drawback is potential
+data loss if losing the associated cache device.
+
+During the boot time grub reads the LVM offline i.e. LVM volumes are not
+activated and mounted, hence it should be fine to read directly from original
+lv since all cached data should have been flushed back in the process of taking
+it offline.
+
+It is also not much helpful to the situation by adding fsync calls to the
+install code. The fsync did not force to write back dirty cache to the original
+device and rather it would update associated cache metadata to complete the
+write transaction with the cache device. IOW the writes to cached blocks still
+go only to the cache device.
+
+To write back dirty cache, as LVM cache did not support dirty cache flush per
+block range, there'no way to do it for file. On the other hand the "cleaner"
+policy is implemented and can be used to write back "all" dirty blocks in a
+cache, which effectively drain all dirty cache gradually to attain and last in
+the "clean" state, which can be useful for shrinking or decommissioning a
+cache. The result and effect is not what we are looking for here.
+
+In conclusion, as it seems no way to enforce file writes to the original
+device, grub may suffer from power failure as it cannot assemble the cache
+device and read the dirty data from it. However since the case is only
+applicable to writeback mode which is sensitive to data lost in nature, I'd
+still like to propose my (relatively simple) patch and treat reading dirty
+cache as improvement.
+
+Upstream-Status: Backport [commit 0454b0445393aafc5600e92ef0c39494e333b135
+from https://git.savannah.gnu.org/git/grub.git]
+
+Signed-off-by: Michael Chang <mchang@suse.com>
+Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
+Signed-off-by: Yongxin Liu <yongxin.liu@windriver.com>
+---
+ grub-core/disk/lvm.c | 190 +++++++++++++++++++++++++++++++++++++++++++++++++++
+ 1 file changed, 190 insertions(+)
+
+diff --git a/grub-core/disk/lvm.c b/grub-core/disk/lvm.c
+index 7b265c7..dc6b83b 100644
+--- a/grub-core/disk/lvm.c
++++ b/grub-core/disk/lvm.c
+@@ -33,6 +33,14 @@
+
+ GRUB_MOD_LICENSE ("GPLv3+");
+
++struct cache_lv
++{
++ struct grub_diskfilter_lv *lv;
++ char *cache_pool;
++ char *origin;
++ struct cache_lv *next;
++};
++
+
+ /* Go the string STR and return the number after STR. *P will point
+ at the number. In case STR is not found, *P will be NULL and the
+@@ -95,6 +103,34 @@ grub_lvm_check_flag (char *p, const char *str, const char *flag)
+ }
+ }
+
++static void
++grub_lvm_free_cache_lvs (struct cache_lv *cache_lvs)
++{
++ struct cache_lv *cache;
++
++ while ((cache = cache_lvs))
++ {
++ cache_lvs = cache_lvs->next;
++
++ if (cache->lv)
++ {
++ unsigned int i;
++
++ for (i = 0; i < cache->lv->segment_count; ++i)
++ if (cache->lv->segments)
++ grub_free (cache->lv->segments[i].nodes);
++ grub_free (cache->lv->segments);
++ grub_free (cache->lv->fullname);
++ grub_free (cache->lv->idname);
++ grub_free (cache->lv->name);
++ }
++ grub_free (cache->lv);
++ grub_free (cache->origin);
++ grub_free (cache->cache_pool);
++ grub_free (cache);
++ }
++}
++
+ static struct grub_diskfilter_vg *
+ grub_lvm_detect (grub_disk_t disk,
+ struct grub_diskfilter_pv_id *id,
+@@ -242,6 +278,8 @@ grub_lvm_detect (grub_disk_t disk,
+
+ if (! vg)
+ {
++ struct cache_lv *cache_lvs = NULL;
++
+ /* First time we see this volume group. We've to create the
+ whole volume group structure. */
+ vg = grub_malloc (sizeof (*vg));
+@@ -671,6 +709,106 @@ grub_lvm_detect (grub_disk_t disk,
+ seg->nodes[seg->node_count - 1].name = tmp;
+ }
+ }
++ else if (grub_memcmp (p, "cache\"",
++ sizeof ("cache\"") - 1) == 0)
++ {
++ struct cache_lv *cache = NULL;
++
++ char *p2, *p3;
++ grub_size_t sz;
++
++ cache = grub_zalloc (sizeof (*cache));
++ if (!cache)
++ goto cache_lv_fail;
++ cache->lv = grub_zalloc (sizeof (*cache->lv));
++ if (!cache->lv)
++ goto cache_lv_fail;
++ grub_memcpy (cache->lv, lv, sizeof (*cache->lv));
++
++ if (lv->fullname)
++ {
++ cache->lv->fullname = grub_strdup (lv->fullname);
++ if (!cache->lv->fullname)
++ goto cache_lv_fail;
++ }
++ if (lv->idname)
++ {
++ cache->lv->idname = grub_strdup (lv->idname);
++ if (!cache->lv->idname)
++ goto cache_lv_fail;
++ }
++ if (lv->name)
++ {
++ cache->lv->name = grub_strdup (lv->name);
++ if (!cache->lv->name)
++ goto cache_lv_fail;
++ }
++
++ skip_lv = 1;
++
++ p2 = grub_strstr (p, "cache_pool = \"");
++ if (!p2)
++ goto cache_lv_fail;
++
++ p2 = grub_strchr (p2, '"');
++ if (!p2)
++ goto cache_lv_fail;
++
++ p3 = ++p2;
++ p3 = grub_strchr (p3, '"');
++ if (!p3)
++ goto cache_lv_fail;
++
++ sz = p3 - p2;
++
++ cache->cache_pool = grub_malloc (sz + 1);
++ if (!cache->cache_pool)
++ goto cache_lv_fail;
++ grub_memcpy (cache->cache_pool, p2, sz);
++ cache->cache_pool[sz] = '\0';
++
++ p2 = grub_strstr (p, "origin = \"");
++ if (!p2)
++ goto cache_lv_fail;
++
++ p2 = grub_strchr (p2, '"');
++ if (!p2)
++ goto cache_lv_fail;
++
++ p3 = ++p2;
++ p3 = grub_strchr (p3, '"');
++ if (!p3)
++ goto cache_lv_fail;
++
++ sz = p3 - p2;
++
++ cache->origin = grub_malloc (sz + 1);
++ if (!cache->origin)
++ goto cache_lv_fail;
++ grub_memcpy (cache->origin, p2, sz);
++ cache->origin[sz] = '\0';
++
++ cache->next = cache_lvs;
++ cache_lvs = cache;
++ break;
++
++ cache_lv_fail:
++ if (cache)
++ {
++ grub_free (cache->origin);
++ grub_free (cache->cache_pool);
++ if (cache->lv)
++ {
++ grub_free (cache->lv->fullname);
++ grub_free (cache->lv->idname);
++ grub_free (cache->lv->name);
++ }
++ grub_free (cache->lv);
++ grub_free (cache);
++ }
++ grub_lvm_free_cache_lvs (cache_lvs);
++ goto fail4;
++ }
+ else
+ {
+ #ifdef GRUB_UTIL
+@@ -747,6 +885,58 @@ grub_lvm_detect (grub_disk_t disk,
+ }
+
+ }
++
++ {
++ struct cache_lv *cache;
++
++ for (cache = cache_lvs; cache; cache = cache->next)
++ {
++ struct grub_diskfilter_lv *lv;
++
++ for (lv = vg->lvs; lv; lv = lv->next)
++ if (grub_strcmp (lv->name, cache->origin) == 0)
++ break;
++ if (lv)
++ {
++ cache->lv->segments = grub_malloc (lv->segment_count * sizeof (*lv->segments));
++ if (!cache->lv->segments)
++ {
++ grub_lvm_free_cache_lvs (cache_lvs);
++ goto fail4;
++ }
++ grub_memcpy (cache->lv->segments, lv->segments, lv->segment_count * sizeof (*lv->segments));
++
++ for (i = 0; i < lv->segment_count; ++i)
++ {
++ struct grub_diskfilter_node *nodes = lv->segments[i].nodes;
++ grub_size_t node_count = lv->segments[i].node_count;
++
++ cache->lv->segments[i].nodes = grub_malloc (node_count * sizeof (*nodes));
++ if (!cache->lv->segments[i].nodes)
++ {
++ for (j = 0; j < i; ++j)
++ grub_free (cache->lv->segments[j].nodes);
++ grub_free (cache->lv->segments);
++ cache->lv->segments = NULL;
++ grub_lvm_free_cache_lvs (cache_lvs);
++ goto fail4;
++ }
++ grub_memcpy (cache->lv->segments[i].nodes, nodes, node_count * sizeof (*nodes));
++ }
++
++ if (cache->lv->segments)
++ {
++ cache->lv->segment_count = lv->segment_count;
++ cache->lv->vg = vg;
++ cache->lv->next = vg->lvs;
++ vg->lvs = cache->lv;
++ cache->lv = NULL;
++ }
++ }
++ }
++ }
++
++ grub_lvm_free_cache_lvs (cache_lvs);
+ if (grub_diskfilter_vg_register (vg))
+ goto fail4;
+ }
+--
+2.14.4
+
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