Merge branch 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull libnvdimm fixes from Dan Williams:
 "These fixes are all tagged for -stable and have received a build
  success notification from the kbuild robot.

   - NVDIMM namespaces, configured to enforce 1GB alignment, fail to
     initialize on platforms that mis-align the start or end of the
     physical address range.

   - The Linux implementation of the BTT (Block Translation Table) is
     incompatible with the UEFI 2.7 definition of the BTT format. The
     BTT layers a software atomic sector semantic on top of an NVDIMM
     namespace. Linux needs to be compatible with the UEFI definition to
     enable boot support or any pre-OS access of data on a BTT enabled
     namespace.

   - A fix for ACPI SMART notification events, this allows a userspace
     monitor to register for health events rather than poll. This has
     been broken since it was initially merged as the unit test
     inadvertently worked around the problem. The urgency for fixing
     this during the -rc series is driven by how expensive it is to poll
     for this data (System Management Mode entry)"

* 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  libnvdimm, btt: Fix an incompatibility in the log layout
  libnvdimm, btt: add a couple of missing kernel-doc lines
  libnvdimm, dax: fix 1GB-aligned namespaces vs physical misalignment
  libnvdimm, pfn: fix start_pad handling for aligned namespaces
  acpi, nfit: fix health event notification

1 files changed, 167 insertions, 34 deletions

diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index e949e3302af4..c586bcdb5190 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -211,12 +211,12 @@ static int btt_map_read(struct arena_info *arena, u32 lba, u32 *mapping,
 	return ret;
 }
 
-static int btt_log_read_pair(struct arena_info *arena, u32 lane,
-			struct log_entry *ent)
+static int btt_log_group_read(struct arena_info *arena, u32 lane,
+			struct log_group *log)
 {
 	return arena_read_bytes(arena,
-			arena->logoff + (2 * lane * LOG_ENT_SIZE), ent,
-			2 * LOG_ENT_SIZE, 0);
+			arena->logoff + (lane * LOG_GRP_SIZE), log,
+			LOG_GRP_SIZE, 0);
 }
 
 static struct dentry *debugfs_root;
@@ -256,6 +256,8 @@ static void arena_debugfs_init(struct arena_info *a, struct dentry *parent,
 	debugfs_create_x64("logoff", S_IRUGO, d, &a->logoff);
 	debugfs_create_x64("info2off", S_IRUGO, d, &a->info2off);
 	debugfs_create_x32("flags", S_IRUGO, d, &a->flags);
+	debugfs_create_u32("log_index_0", S_IRUGO, d, &a->log_index[0]);
+	debugfs_create_u32("log_index_1", S_IRUGO, d, &a->log_index[1]);
 }
 
 static void btt_debugfs_init(struct btt *btt)
@@ -274,6 +276,11 @@ static void btt_debugfs_init(struct btt *btt)
 	}
 }
 
+static u32 log_seq(struct log_group *log, int log_idx)
+{
+	return le32_to_cpu(log->ent[log_idx].seq);
+}
+
 /*
  * This function accepts two log entries, and uses the
  * sequence number to find the 'older' entry.
@@ -283,8 +290,10 @@ static void btt_debugfs_init(struct btt *btt)
  *
  * TODO The logic feels a bit kludge-y. make it better..
  */
-static int btt_log_get_old(struct log_entry *ent)
+static int btt_log_get_old(struct arena_info *a, struct log_group *log)
 {
+	int idx0 = a->log_index[0];
+	int idx1 = a->log_index[1];
 	int old;
 
 	/*
@@ -292,23 +301,23 @@ static int btt_log_get_old(struct log_entry *ent)
 	 * the next time, the following logic works out to put this
 	 * (next) entry into [1]
 	 */
-	if (ent[0].seq == 0) {
-		ent[0].seq = cpu_to_le32(1);
+	if (log_seq(log, idx0) == 0) {
+		log->ent[idx0].seq = cpu_to_le32(1);
 		return 0;
 	}
 
-	if (ent[0].seq == ent[1].seq)
+	if (log_seq(log, idx0) == log_seq(log, idx1))
 		return -EINVAL;
-	if (le32_to_cpu(ent[0].seq) + le32_to_cpu(ent[1].seq) > 5)
+	if (log_seq(log, idx0) + log_seq(log, idx1) > 5)
 		return -EINVAL;
 
-	if (le32_to_cpu(ent[0].seq) < le32_to_cpu(ent[1].seq)) {
-		if (le32_to_cpu(ent[1].seq) - le32_to_cpu(ent[0].seq) == 1)
+	if (log_seq(log, idx0) < log_seq(log, idx1)) {
+		if ((log_seq(log, idx1) - log_seq(log, idx0)) == 1)
 			old = 0;
 		else
 			old = 1;
 	} else {
-		if (le32_to_cpu(ent[0].seq) - le32_to_cpu(ent[1].seq) == 1)
+		if ((log_seq(log, idx0) - log_seq(log, idx1)) == 1)
 			old = 1;
 		else
 			old = 0;
@@ -328,17 +337,18 @@ static int btt_log_read(struct arena_info *arena, u32 lane,
 {
 	int ret;
 	int old_ent, ret_ent;
-	struct log_entry log[2];
+	struct log_group log;
 
-	ret = btt_log_read_pair(arena, lane, log);
+	ret = btt_log_group_read(arena, lane, &log);
 	if (ret)
 		return -EIO;
 
-	old_ent = btt_log_get_old(log);
+	old_ent = btt_log_get_old(arena, &log);
 	if (old_ent < 0 || old_ent > 1) {
 		dev_err(to_dev(arena),
 				"log corruption (%d): lane %d seq [%d, %d]\n",
-			old_ent, lane, log[0].seq, log[1].seq);
+				old_ent, lane, log.ent[arena->log_index[0]].seq,
+				log.ent[arena->log_index[1]].seq);
 		/* TODO set error state? */
 		return -EIO;
 	}
@@ -346,7 +356,7 @@ static int btt_log_read(struct arena_info *arena, u32 lane,
 	ret_ent = (old_flag ? old_ent : (1 - old_ent));
 
 	if (ent != NULL)
-		memcpy(ent, &log[ret_ent], LOG_ENT_SIZE);
+		memcpy(ent, &log.ent[arena->log_index[ret_ent]], LOG_ENT_SIZE);
 
 	return ret_ent;
 }
@@ -360,17 +370,13 @@ static int __btt_log_write(struct arena_info *arena, u32 lane,
 			u32 sub, struct log_entry *ent, unsigned long flags)
 {
 	int ret;
-	/*
-	 * Ignore the padding in log_entry for calculating log_half.
-	 * The entry is 'committed' when we write the sequence number,
-	 * and we want to ensure that that is the last thing written.
-	 * We don't bother writing the padding as that would be extra
-	 * media wear and write amplification
-	 */
-	unsigned int log_half = (LOG_ENT_SIZE - 2 * sizeof(u64)) / 2;
-	u64 ns_off = arena->logoff + (((2 * lane) + sub) * LOG_ENT_SIZE);
+	u32 group_slot = arena->log_index[sub];
+	unsigned int log_half = LOG_ENT_SIZE / 2;
 	void *src = ent;
+	u64 ns_off;
 
+	ns_off = arena->logoff + (lane * LOG_GRP_SIZE) +
+		(group_slot * LOG_ENT_SIZE);
 	/* split the 16B write into atomic, durable halves */
 	ret = arena_write_bytes(arena, ns_off, src, log_half, flags);
 	if (ret)
@@ -453,7 +459,7 @@ static int btt_log_init(struct arena_info *arena)
 {
 	size_t logsize = arena->info2off - arena->logoff;
 	size_t chunk_size = SZ_4K, offset = 0;
-	struct log_entry log;
+	struct log_entry ent;
 	void *zerobuf;
 	int ret;
 	u32 i;
@@ -485,11 +491,11 @@ static int btt_log_init(struct arena_info *arena)
 	}
 
 	for (i = 0; i < arena->nfree; i++) {
-		log.lba = cpu_to_le32(i);
-		log.old_map = cpu_to_le32(arena->external_nlba + i);
-		log.new_map = cpu_to_le32(arena->external_nlba + i);
-		log.seq = cpu_to_le32(LOG_SEQ_INIT);
-		ret = __btt_log_write(arena, i, 0, &log, 0);
+		ent.lba = cpu_to_le32(i);
+		ent.old_map = cpu_to_le32(arena->external_nlba + i);
+		ent.new_map = cpu_to_le32(arena->external_nlba + i);
+		ent.seq = cpu_to_le32(LOG_SEQ_INIT);
+		ret = __btt_log_write(arena, i, 0, &ent, 0);
 		if (ret)
 			goto free;
 	}
@@ -594,6 +600,123 @@ static int btt_freelist_init(struct arena_info *arena)
 	return 0;
 }
 
+static bool ent_is_padding(struct log_entry *ent)
+{
+	return (ent->lba == 0) && (ent->old_map == 0) && (ent->new_map == 0)
+		&& (ent->seq == 0);
+}
+
+/*
+ * Detecting valid log indices: We read a log group (see the comments in btt.h
+ * for a description of a 'log_group' and its 'slots'), and iterate over its
+ * four slots. We expect that a padding slot will be all-zeroes, and use this
+ * to detect a padding slot vs. an actual entry.
+ *
+ * If a log_group is in the initial state, i.e. hasn't been used since the
+ * creation of this BTT layout, it will have three of the four slots with
+ * zeroes. We skip over these log_groups for the detection of log_index. If
+ * all log_groups are in the initial state (i.e. the BTT has never been
+ * written to), it is safe to assume the 'new format' of log entries in slots
+ * (0, 1).
+ */
+static int log_set_indices(struct arena_info *arena)
+{
+	bool idx_set = false, initial_state = true;
+	int ret, log_index[2] = {-1, -1};
+	u32 i, j, next_idx = 0;
+	struct log_group log;
+	u32 pad_count = 0;
+
+	for (i = 0; i < arena->nfree; i++) {
+		ret = btt_log_group_read(arena, i, &log);
+		if (ret < 0)
+			return ret;
+
+		for (j = 0; j < 4; j++) {
+			if (!idx_set) {
+				if (ent_is_padding(&log.ent[j])) {
+					pad_count++;
+					continue;
+				} else {
+					/* Skip if index has been recorded */
+					if ((next_idx == 1) &&
+						(j == log_index[0]))
+						continue;
+					/* valid entry, record index */
+					log_index[next_idx] = j;
+					next_idx++;
+				}
+				if (next_idx == 2) {
+					/* two valid entries found */
+					idx_set = true;
+				} else if (next_idx > 2) {
+					/* too many valid indices */
+					return -ENXIO;
+				}
+			} else {
+				/*
+				 * once the indices have been set, just verify
+				 * that all subsequent log groups are either in
+				 * their initial state or follow the same
+				 * indices.
+				 */
+				if (j == log_index[0]) {
+					/* entry must be 'valid' */
+					if (ent_is_padding(&log.ent[j]))
+						return -ENXIO;
+				} else if (j == log_index[1]) {
+					;
+					/*
+					 * log_index[1] can be padding if the
+					 * lane never got used and it is still
+					 * in the initial state (three 'padding'
+					 * entries)
+					 */
+				} else {
+					/* entry must be invalid (padding) */
+					if (!ent_is_padding(&log.ent[j]))
+						return -ENXIO;
+				}
+			}
+		}
+		/*
+		 * If any of the log_groups have more than one valid,
+		 * non-padding entry, then the we are no longer in the
+		 * initial_state
+		 */
+		if (pad_count < 3)
+			initial_state = false;
+		pad_count = 0;
+	}
+
+	if (!initial_state && !idx_set)
+		return -ENXIO;
+
+	/*
+	 * If all the entries in the log were in the initial state,
+	 * assume new padding scheme
+	 */
+	if (initial_state)
+		log_index[1] = 1;
+
+	/*
+	 * Only allow the known permutations of log/padding indices,
+	 * i.e. (0, 1), and (0, 2)
+	 */
+	if ((log_index[0] == 0) && ((log_index[1] == 1) || (log_index[1] == 2)))
+		; /* known index possibilities */
+	else {
+		dev_err(to_dev(arena), "Found an unknown padding scheme\n");
+		return -ENXIO;
+	}
+
+	arena->log_index[0] = log_index[0];
+	arena->log_index[1] = log_index[1];
+	dev_dbg(to_dev(arena), "log_index_0 = %d\n", log_index[0]);
+	dev_dbg(to_dev(arena), "log_index_1 = %d\n", log_index[1]);
+	return 0;
+}
+
 static int btt_rtt_init(struct arena_info *arena)
 {
 	arena->rtt = kcalloc(arena->nfree, sizeof(u32), GFP_KERNEL);
@@ -650,8 +773,7 @@ static struct arena_info *alloc_arena(struct btt *btt, size_t size,
 	available -= 2 * BTT_PG_SIZE;
 
 	/* The log takes a fixed amount of space based on nfree */
-	logsize = roundup(2 * arena->nfree * sizeof(struct log_entry),
-				BTT_PG_SIZE);
+	logsize = roundup(arena->nfree * LOG_GRP_SIZE, BTT_PG_SIZE);
 	available -= logsize;
 
 	/* Calculate optimal split between map and data area */
@@ -668,6 +790,10 @@ static struct arena_info *alloc_arena(struct btt *btt, size_t size,
 	arena->mapoff = arena->dataoff + datasize;
 	arena->logoff = arena->mapoff + mapsize;
 	arena->info2off = arena->logoff + logsize;
+
+	/* Default log indices are (0,1) */
+	arena->log_index[0] = 0;
+	arena->log_index[1] = 1;
 	return arena;
 }
 
@@ -758,6 +884,13 @@ static int discover_arenas(struct btt *btt)
 		arena->external_lba_start = cur_nlba;
 		parse_arena_meta(arena, super, cur_off);
 
+		ret = log_set_indices(arena);
+		if (ret) {
+			dev_err(to_dev(arena),
+				"Unable to deduce log/padding indices\n");
+			goto out;
+		}
+
 		mutex_init(&arena->err_lock);
 		ret = btt_freelist_init(arena);
 		if (ret)