libnvdimm: clear the internal poison_list when clearing badblocks

nvdimm_clear_poison cleared the user-visible badblocks, and sent
commands to the NVDIMM to clear the areas marked as 'poison', but it
neglected to clear the same areas from the internal poison_list which is
used to marshal ARS results before sorting them by namespace. As a
result, once on-demand ARS functionality was added:

37b137f nfit, libnvdimm: allow an ARS scrub to be triggered on demand

A scrub triggered from either sysfs or an MCE was found to be adding
stale entries that had been cleared from gendisk->badblocks, but were
still present in nvdimm_bus->poison_list. Additionally, the stale entries
could be triggered into producing stale disk->badblocks by simply disabling
and re-enabling the namespace or region.

This adds the missing step of clearing poison_list entries when clearing
poison, so that it is always in sync with badblocks.

Fixes: 37b137f ("nfit, libnvdimm: allow an ARS scrub to be triggered on demand")
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

3 files changed, 73 insertions, 4 deletions

diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
index 458daf927336..8493a2559daa 100644
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -213,6 +213,8 @@ long nvdimm_clear_poison(struct device *dev, phys_addr_t phys,
                 return rc;
         if (cmd_rc < 0)
                 return cmd_rc;
+
+        nvdimm_clear_from_poison_list(nvdimm_bus, phys, len);
         return clear_err.cleared;
 }
 EXPORT_SYMBOL_GPL(nvdimm_clear_poison);
diff --git a/drivers/nvdimm/core.c b/drivers/nvdimm/core.c
index 715583f69d28..42e40db4651b 100644
--- a/drivers/nvdimm/core.c
+++ b/drivers/nvdimm/core.c
@@ -541,11 +541,12 @@ void nvdimm_badblocks_populate(struct nd_region *nd_region,
 }
 EXPORT_SYMBOL_GPL(nvdimm_badblocks_populate);
 
-static int add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length)
+static int add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length,
+                        gfp_t flags)
 {
         struct nd_poison *pl;
 
-        pl = kzalloc(sizeof(*pl), GFP_KERNEL);
+        pl = kzalloc(sizeof(*pl), flags);
         if (!pl)
                 return -ENOMEM;
 
@@ -561,7 +562,7 @@ static int bus_add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length)
         struct nd_poison *pl;
 
         if (list_empty(&nvdimm_bus->poison_list))
-                return add_poison(nvdimm_bus, addr, length);
+                return add_poison(nvdimm_bus, addr, length, GFP_KERNEL);
 
         /*
          * There is a chance this is a duplicate, check for those first.
@@ -581,7 +582,7 @@ static int bus_add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length)
          * as any overlapping ranges will get resolved when the list is consumed
          * and converted to badblocks
          */
-        return add_poison(nvdimm_bus, addr, length);
+        return add_poison(nvdimm_bus, addr, length, GFP_KERNEL);
 }
 
 int nvdimm_bus_add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length)
@@ -596,6 +597,70 @@ int nvdimm_bus_add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length)
 }
 EXPORT_SYMBOL_GPL(nvdimm_bus_add_poison);
 
+void nvdimm_clear_from_poison_list(struct nvdimm_bus *nvdimm_bus,
+                phys_addr_t start, unsigned int len)
+{
+        struct list_head *poison_list = &nvdimm_bus->poison_list;
+        u64 clr_end = start + len - 1;
+        struct nd_poison *pl, *next;
+
+        nvdimm_bus_lock(&nvdimm_bus->dev);
+        WARN_ON_ONCE(list_empty(poison_list));
+
+        /*
+         * [start, clr_end] is the poison interval being cleared.
+         * [pl->start, pl_end] is the poison_list entry we're comparing
+         * the above interval against. The poison list entry may need
+         * to be modified (update either start or length), deleted, or
+         * split into two based on the overlap characteristics
+         */
+
+        list_for_each_entry_safe(pl, next, poison_list, list) {
+                u64 pl_end = pl->start + pl->length - 1;
+
+                /* Skip intervals with no intersection */
+                if (pl_end < start)
+                        continue;
+                if (pl->start >  clr_end)
+                        continue;
+                /* Delete completely overlapped poison entries */
+                if ((pl->start >= start) && (pl_end <= clr_end)) {
+                        list_del(&pl->list);
+                        kfree(pl);
+                        continue;
+                }
+                /* Adjust start point of partially cleared entries */
+                if ((start <= pl->start) && (clr_end > pl->start)) {
+                        pl->length -= clr_end - pl->start + 1;
+                        pl->start = clr_end + 1;
+                        continue;
+                }
+                /* Adjust pl->length for partial clearing at the tail end */
+                if ((pl->start < start) && (pl_end <= clr_end)) {
+                        /* pl->start remains the same */
+                        pl->length = start - pl->start;
+                        continue;
+                }
+                /*
+                 * If clearing in the middle of an entry, we split it into
+                 * two by modifying the current entry to represent one half of
+                 * the split, and adding a new entry for the second half.
+                 */
+                if ((pl->start < start) && (pl_end > clr_end)) {
+                        u64 new_start = clr_end + 1;
+                        u64 new_len = pl_end - new_start + 1;
+
+                        /* Add new entry covering the right half */
+                        add_poison(nvdimm_bus, new_start, new_len, GFP_NOIO);
+                        /* Adjust this entry to cover the left half */
+                        pl->length = start - pl->start;
+                        continue;
+                }
+        }
+        nvdimm_bus_unlock(&nvdimm_bus->dev);
+}
+EXPORT_SYMBOL_GPL(nvdimm_clear_from_poison_list);
+
 #ifdef CONFIG_BLK_DEV_INTEGRITY
 int nd_integrity_init(struct gendisk *disk, unsigned long meta_size)
 {
diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
index ad18d0531b6e..4a5f8c51f2a5 100644
--- a/include/linux/libnvdimm.h
+++ b/include/linux/libnvdimm.h
@@ -129,6 +129,8 @@ static inline struct nd_blk_region_desc *to_blk_region_desc(
 }
 
 int nvdimm_bus_add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length);
+void nvdimm_clear_from_poison_list(struct nvdimm_bus *nvdimm_bus,
+                phys_addr_t start, unsigned int len);
 struct nvdimm_bus *nvdimm_bus_register(struct device *parent,
                 struct nvdimm_bus_descriptor *nfit_desc);
 void nvdimm_bus_unregister(struct nvdimm_bus *nvdimm_bus);