Merge pull request #109 from versity/zab/server_statfs_stable_blocks

Zab/server statfs stable blocks

kmod/src/alloc.c

@@ -1582,12 +1582,10 @@ out:
  * call the caller's callback.  This assumes that the super it's reading
  * could be stale and will retry if it encounters stale blocks.
  */
-int scoutfs_alloc_foreach(struct super_block *sb,
-			  scoutfs_alloc_foreach_cb_t cb, void *arg)
+int scoutfs_alloc_foreach(struct super_block *sb, scoutfs_alloc_foreach_cb_t cb, void *arg)
 {
 	struct scoutfs_super_block *super = NULL;
-	struct scoutfs_block_ref stale_refs[2] = {{0,}};
-	struct scoutfs_block_ref refs[2] = {{0,}};
+	DECLARE_SAVED_REFS(saved);
 	int ret;
 
 	super = kmalloc(sizeof(struct scoutfs_super_block), GFP_NOFS);
@@ -1596,26 +1594,18 @@ int scoutfs_alloc_foreach(struct super_block *sb,
 		goto out;
 	}
 
-retry:
-	ret = scoutfs_read_super(sb, super);
-	if (ret < 0)
-		goto out;
+	do {
+		ret = scoutfs_read_super(sb, super);
+		if (ret < 0)
+			goto out;
 
-	refs[0] = super->logs_root.ref;
-	refs[1] = super->srch_root.ref;
+		ret = scoutfs_alloc_foreach_super(sb, super, cb, arg);
+
+		ret = scoutfs_block_check_stale(sb, ret, &saved, &super->logs_root.ref,
+						&super->srch_root.ref);
+	} while (ret == -ESTALE);
 
-	ret = scoutfs_alloc_foreach_super(sb, super, cb, arg);
 out:
-	if (ret == -ESTALE) {
-		if (memcmp(&stale_refs, &refs, sizeof(refs)) == 0) {
-			ret = -EIO;
-		} else {
-			BUILD_BUG_ON(sizeof(stale_refs) != sizeof(refs));
-			memcpy(stale_refs, refs, sizeof(stale_refs));
-			goto retry;
-		}
-	}
-
 	kfree(super);
 	return ret;
 }

kmod/src/block.c

@@ -677,7 +677,7 @@ out:
 int scoutfs_block_read_ref(struct super_block *sb, struct scoutfs_block_ref *ref, u32 magic,
 			   struct scoutfs_block **bl_ret)
 {
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
 	struct scoutfs_block_header *hdr;
 	struct block_private *bp = NULL;
 	bool retried = false;
@@ -701,7 +701,7 @@ retry:
 		set_bit(BLOCK_BIT_CRC_VALID, &bp->bits);
 	}
 
-	if (hdr->magic != cpu_to_le32(magic) || hdr->fsid != super->hdr.fsid ||
+	if (hdr->magic != cpu_to_le32(magic) || hdr->fsid != cpu_to_le64(sbi->fsid) ||
 	    hdr->seq != ref->seq || hdr->blkno != ref->blkno) {
 		ret = -ESTALE;
 		goto out;
@@ -728,6 +728,36 @@ out:
 	return ret;
 }
 
+static bool stale_refs_match(struct scoutfs_block_ref *caller, struct scoutfs_block_ref *saved)
+{
+	return !caller || (caller->blkno == saved->blkno && caller->seq == saved->seq);
+}
+
+/*
+ * Check if a read of a reference that gave ESTALE should be retried or
+ * should generate a hard error.  If this is the second time we got
+ * ESTALE from the same refs then we return EIO and the caller should
+ * stop.  As long as we keep seeing different refs we'll return ESTALE
+ * and the caller can keep trying.
+ */
+int scoutfs_block_check_stale(struct super_block *sb, int ret,
+			      struct scoutfs_block_saved_refs *saved,
+			      struct scoutfs_block_ref *a, struct scoutfs_block_ref *b)
+{
+	if (ret == -ESTALE) {
+		if (stale_refs_match(a, &saved->refs[0]) && stale_refs_match(b, &saved->refs[1])){
+			ret = -EIO;
+		} else {
+			if (a)
+				saved->refs[0] = *a;
+			if (b)
+				saved->refs[1] = *b;
+		}
+	}
+
+	return ret;
+}
+
 void scoutfs_block_put(struct super_block *sb, struct scoutfs_block *bl)
 {
 	if (!IS_ERR_OR_NULL(bl))
@@ -797,7 +827,7 @@ int scoutfs_block_dirty_ref(struct super_block *sb, struct scoutfs_alloc *alloc,
 			    u32 magic, struct scoutfs_block **bl_ret,
 			    u64 dirty_blkno, u64 *ref_blkno)
 {
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
 	struct scoutfs_block *cow_bl = NULL;
 	struct scoutfs_block *bl = NULL;
 	struct block_private *exist_bp = NULL;
@@ -865,7 +895,7 @@ int scoutfs_block_dirty_ref(struct super_block *sb, struct scoutfs_alloc *alloc,
 
 	hdr = bl->data;
 	hdr->magic = cpu_to_le32(magic);
-	hdr->fsid = super->hdr.fsid;
+	hdr->fsid = cpu_to_le64(sbi->fsid);
 	hdr->blkno = cpu_to_le64(bl->blkno);
 	prandom_bytes(&hdr->seq, sizeof(hdr->seq));
 

kmod/src/block.h

@@ -13,6 +13,17 @@ struct scoutfs_block {
 	void *priv;
 };
 
+struct scoutfs_block_saved_refs {
+	struct scoutfs_block_ref refs[2];
+};
+
+#define DECLARE_SAVED_REFS(name) \
+	struct scoutfs_block_saved_refs name = {{{0,}}}
+
+int scoutfs_block_check_stale(struct super_block *sb, int ret,
+			      struct scoutfs_block_saved_refs *saved,
+			      struct scoutfs_block_ref *a, struct scoutfs_block_ref *b);
+
 int scoutfs_block_read_ref(struct super_block *sb, struct scoutfs_block_ref *ref, u32 magic,
 			   struct scoutfs_block **bl_ret);
 void scoutfs_block_put(struct super_block *sb, struct scoutfs_block *bl);

kmod/src/client.c

@@ -356,7 +356,6 @@ static int client_greeting(struct super_block *sb,
 {
 	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
 	struct client_info *client = sbi->client_info;
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
 	struct scoutfs_net_greeting *gr = resp;
 	bool new_server;
 	int ret;
@@ -371,9 +370,9 @@ static int client_greeting(struct super_block *sb,
 		goto out;
 	}
 
-	if (gr->fsid != super->hdr.fsid) {
+	if (gr->fsid != cpu_to_le64(sbi->fsid)) {
 		scoutfs_warn(sb, "server greeting response fsid 0x%llx did not match client fsid 0x%llx",
-			     le64_to_cpu(gr->fsid), le64_to_cpu(super->hdr.fsid));
+			     le64_to_cpu(gr->fsid), sbi->fsid);
 		ret = -EINVAL;
 		goto out;
 	}
@@ -476,7 +475,6 @@ static void scoutfs_client_connect_worker(struct work_struct *work)
 						  connect_dwork.work);
 	struct super_block *sb = client->sb;
 	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &sbi->super;
 	struct scoutfs_mount_options opts;
 	struct scoutfs_net_greeting greet;
 	struct sockaddr_in sin;
@@ -508,7 +506,7 @@ static void scoutfs_client_connect_worker(struct work_struct *work)
 		goto out;
 
 	/* send a greeting to verify endpoints of each connection */
-	greet.fsid = super->hdr.fsid;
+	greet.fsid = cpu_to_le64(sbi->fsid);
 	greet.fmt_vers = cpu_to_le64(sbi->fmt_vers);
 	greet.server_term = cpu_to_le64(client->server_term);
 	greet.rid = cpu_to_le64(sbi->rid);

kmod/src/counters.h

@@ -187,8 +187,6 @@
 	EXPAND_COUNTER(srch_search_retry_empty)			\
 	EXPAND_COUNTER(srch_search_sorted)			\
 	EXPAND_COUNTER(srch_search_sorted_block)		\
-	EXPAND_COUNTER(srch_search_stale_eio)			\
-	EXPAND_COUNTER(srch_search_stale_retry)			\
 	EXPAND_COUNTER(srch_search_xattrs)			\
 	EXPAND_COUNTER(srch_read_stale)				\
 	EXPAND_COUNTER(statfs)					\

kmod/src/forest.c

@@ -78,11 +78,6 @@ struct forest_refs {
 	struct scoutfs_block_ref logs_ref;
 };
 
-/* initialize some refs that initially aren't equal */
-#define DECLARE_STALE_TRACKING_SUPER_REFS(a, b)		\
-	struct forest_refs a = {{cpu_to_le64(0),}};	\
-	struct forest_refs b = {{cpu_to_le64(1),}}
-
 struct forest_bloom_nrs {
 	unsigned int nrs[SCOUTFS_FOREST_BLOOM_NRS];
 };
@@ -136,11 +131,11 @@ static struct scoutfs_block *read_bloom_ref(struct super_block *sb, struct scout
 int scoutfs_forest_next_hint(struct super_block *sb, struct scoutfs_key *key,
 			     struct scoutfs_key *next)
 {
-	DECLARE_STALE_TRACKING_SUPER_REFS(prev_refs, refs);
 	struct scoutfs_net_roots roots;
 	struct scoutfs_btree_root item_root;
 	struct scoutfs_log_trees *lt;
 	SCOUTFS_BTREE_ITEM_REF(iref);
+	DECLARE_SAVED_REFS(saved);
 	struct scoutfs_key found;
 	struct scoutfs_key ltk;
 	bool checked_fs;
@@ -155,8 +150,6 @@ retry:
 		goto out;
 
 	trace_scoutfs_forest_using_roots(sb, &roots.fs_root, &roots.logs_root);
-	refs.fs_ref = roots.fs_root.ref;
-	refs.logs_ref = roots.logs_root.ref;
 
 	scoutfs_key_init_log_trees(&ltk, 0, 0);
 	checked_fs = false;
@@ -212,14 +205,10 @@ retry:
 		}
 	}
 
-	if (ret == -ESTALE) {
-		if (memcmp(&prev_refs, &refs, sizeof(refs)) == 0)
-			return -EIO;
-		prev_refs = refs;
+	ret = scoutfs_block_check_stale(sb, ret, &saved, &roots.fs_root.ref, &roots.logs_root.ref);
+	if (ret == -ESTALE)
 		goto retry;
-	}
 out:
-
 	return ret;
 }
 
@@ -541,9 +530,8 @@ void scoutfs_forest_dec_inode_count(struct super_block *sb)
 
 /*
  * Return the total inode count from the super block and all the
- * log_btrees it references.   This assumes it's working with a block
- * reference hierarchy that should be fully consistent.   If we see
- * ESTALE we've hit persistent corruption.
+ * log_btrees it references.  ESTALE from read blocks is returned to the
+ * caller who is expected to retry or return hard errors.
  */
 int scoutfs_forest_inode_count(struct super_block *sb, struct scoutfs_super_block *super,
 			       u64 *inode_count)
@@ -572,8 +560,6 @@ int scoutfs_forest_inode_count(struct super_block *sb, struct scoutfs_super_bloc
 		if (ret < 0) {
 			if (ret == -ENOENT)
 				ret = 0;
-			else if (ret == -ESTALE)
-				ret = -EIO;
 			break;
 		}
 	}

kmod/src/quorum.c

@@ -114,6 +114,7 @@ struct quorum_status {
 
 struct quorum_info {
 	struct super_block *sb;
+	struct scoutfs_quorum_config qconf;
 	struct work_struct work;
 	struct socket *sock;
 	bool shutdown;
@@ -134,11 +135,18 @@ struct quorum_info {
 #define DECLARE_QUORUM_INFO_KOBJ(kobj, name) \
 	DECLARE_QUORUM_INFO(SCOUTFS_SYSFS_ATTRS_SB(kobj), name)
 
-static bool quorum_slot_present(struct scoutfs_super_block *super, int i)
+static bool quorum_slot_present(struct scoutfs_quorum_config *qconf, int i)
 {
 	BUG_ON(i < 0 || i > SCOUTFS_QUORUM_MAX_SLOTS);
 
-	return super->qconf.slots[i].addr.v4.family == cpu_to_le16(SCOUTFS_AF_IPV4);
+	return qconf->slots[i].addr.v4.family == cpu_to_le16(SCOUTFS_AF_IPV4);
+}
+
+static void quorum_slot_sin(struct scoutfs_quorum_config *qconf, int i, struct sockaddr_in *sin)
+{
+	BUG_ON(i < 0 || i >= SCOUTFS_QUORUM_MAX_SLOTS);
+
+	scoutfs_addr_to_sin(sin, &qconf->slots[i].addr);
 }
 
 static ktime_t election_timeout(void)
@@ -160,7 +168,6 @@ static ktime_t heartbeat_timeout(void)
 static int create_socket(struct super_block *sb)
 {
 	DECLARE_QUORUM_INFO(sb, qinf);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
 	struct socket *sock = NULL;
 	struct sockaddr_in sin;
 	int addrlen;
@@ -174,7 +181,7 @@ static int create_socket(struct super_block *sb)
 
 	sock->sk->sk_allocation = GFP_NOFS;
 
-	scoutfs_quorum_slot_sin(super, qinf->our_quorum_slot_nr, &sin);
+	quorum_slot_sin(&qinf->qconf, qinf->our_quorum_slot_nr, &sin);
 
 	addrlen = sizeof(sin);
 	ret = kernel_bind(sock, (struct sockaddr *)&sin, addrlen);
@@ -204,13 +211,13 @@ static __le32 quorum_message_crc(struct scoutfs_quorum_message *qmes)
 static void send_msg_members(struct super_block *sb, int type, u64 term,
 			     int only)
 {
+	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
 	DECLARE_QUORUM_INFO(sb, qinf);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
 	ktime_t now;
 	int i;
 
 	struct scoutfs_quorum_message qmes = {
-		.fsid = super->hdr.fsid,
+		.fsid = cpu_to_le64(sbi->fsid),
 		.term = cpu_to_le64(term),
 		.type = type,
 		.from = qinf->our_quorum_slot_nr,
@@ -234,11 +241,11 @@ static void send_msg_members(struct super_block *sb, int type, u64 term,
 
 
 	for (i = 0; i < SCOUTFS_QUORUM_MAX_SLOTS; i++) {
-		if (!quorum_slot_present(super, i) ||
+		if (!quorum_slot_present(&qinf->qconf, i) ||
 		    (only >= 0 && i != only) || i == qinf->our_quorum_slot_nr)
 			continue;
 
-		scoutfs_quorum_slot_sin(super, i, &sin);
+		scoutfs_quorum_slot_sin(&qinf->qconf, i, &sin);
 		now = ktime_get();
 		kernel_sendmsg(qinf->sock, &mh, &kv, 1, kv.iov_len);
 
@@ -266,7 +273,7 @@ static int recv_msg(struct super_block *sb, struct quorum_host_msg *msg,
 		    ktime_t abs_to)
 {
 	DECLARE_QUORUM_INFO(sb, qinf);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
 	struct scoutfs_quorum_message qmes;
 	struct timeval tv;
 	ktime_t rel_to;
@@ -309,10 +316,10 @@ static int recv_msg(struct super_block *sb, struct quorum_host_msg *msg,
 
 	if (ret != sizeof(qmes) ||
 	    qmes.crc != quorum_message_crc(&qmes) ||
-	    qmes.fsid != super->hdr.fsid ||
+	    qmes.fsid != cpu_to_le64(sbi->fsid) ||
 	    qmes.type >= SCOUTFS_QUORUM_MSG_INVALID ||
 	    qmes.from >= SCOUTFS_QUORUM_MAX_SLOTS ||
-	    !quorum_slot_present(super, qmes.from)) {
+	    !quorum_slot_present(&qinf->qconf, qmes.from)) {
 		/* should we be trying to open a new socket? */
 		scoutfs_inc_counter(sb, quorum_recv_invalid);
 		return -EAGAIN;
@@ -342,7 +349,7 @@ static int read_quorum_block(struct super_block *sb, u64 blkno, struct scoutfs_q
 			     bool check_rid)
 {
 	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &sbi->super;
+	const u64 fsid = sbi->fsid;
 	const u64 rid = sbi->rid;
 	char msg[150];
 	__le32 crc;
@@ -367,9 +374,9 @@ static int read_quorum_block(struct super_block *sb, u64 blkno, struct scoutfs_q
 	else if (le32_to_cpu(blk->hdr.magic) != SCOUTFS_BLOCK_MAGIC_QUORUM) 
 		snprintf(msg, sizeof(msg), "blk magic %08x != %08x",
 			 le32_to_cpu(blk->hdr.magic), SCOUTFS_BLOCK_MAGIC_QUORUM);
-	else if (blk->hdr.fsid != super->hdr.fsid)
+	else if (blk->hdr.fsid != cpu_to_le64(fsid))
 		snprintf(msg, sizeof(msg), "blk fsid %016llx != %016llx",
-			 le64_to_cpu(blk->hdr.fsid), le64_to_cpu(super->hdr.fsid));
+			 le64_to_cpu(blk->hdr.fsid), fsid);
 	else if (le64_to_cpu(blk->hdr.blkno) != blkno)
 		snprintf(msg, sizeof(msg), "blk blkno %llu != %llu",
 			 le64_to_cpu(blk->hdr.blkno), blkno);
@@ -410,8 +417,7 @@ out:
  */
 static void read_greatest_term(struct super_block *sb, u64 *term)
 {
-	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &sbi->super;
+	DECLARE_QUORUM_INFO(sb, qinf);
 	struct scoutfs_quorum_block blk;
 	int ret;
 	int e;
@@ -420,7 +426,7 @@ static void read_greatest_term(struct super_block *sb, u64 *term)
 	*term = 0;
 
 	for (s = 0; s < SCOUTFS_QUORUM_MAX_SLOTS; s++) {
-		if (!quorum_slot_present(super, s))
+		if (!quorum_slot_present(&qinf->qconf, s))
 			continue;
 
 		ret = read_quorum_block(sb, SCOUTFS_QUORUM_BLKNO + s, &blk, false);
@@ -514,14 +520,15 @@ static int update_quorum_block(struct super_block *sb, int event, u64 term, bool
  * keeps us from being fenced while we allow userspace fencing to take a
  * reasonably long time.  We still want to timeout eventually.
  */
-int scoutfs_quorum_fence_leaders(struct super_block *sb, u64 term)
+int scoutfs_quorum_fence_leaders(struct super_block *sb, struct scoutfs_quorum_config *qconf,
+				 u64 term)
 {
 #define NR_OLD 2
 	struct scoutfs_quorum_block_event old[SCOUTFS_QUORUM_MAX_SLOTS][NR_OLD] = {{{0,}}};
 	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &sbi->super;
 	struct scoutfs_quorum_block blk;
 	struct sockaddr_in sin;
+	const __le64 lefsid = cpu_to_le64(sbi->fsid);
 	const u64 rid = sbi->rid;
 	bool fence_started = false;
 	u64 fenced = 0;
@@ -534,7 +541,7 @@ int scoutfs_quorum_fence_leaders(struct super_block *sb, u64 term)
 	BUILD_BUG_ON(SCOUTFS_QUORUM_BLOCKS < SCOUTFS_QUORUM_MAX_SLOTS);
 
 	for (i = 0; i < SCOUTFS_QUORUM_MAX_SLOTS; i++) {
-		if (!quorum_slot_present(super, i))
+		if (!quorum_slot_present(qconf, i))
 			continue;
 
 		ret = read_quorum_block(sb, SCOUTFS_QUORUM_BLKNO + i, &blk, false);
@@ -567,11 +574,11 @@ int scoutfs_quorum_fence_leaders(struct super_block *sb, u64 term)
 				continue;
 
 			scoutfs_inc_counter(sb, quorum_fence_leader);
-			scoutfs_quorum_slot_sin(super, i, &sin);
+			quorum_slot_sin(qconf, i, &sin);
 			fence_rid = old[i][j].rid;
 
 			scoutfs_info(sb, "fencing previous leader "SCSBF" at term %llu in slot %u with address "SIN_FMT,
-				     SCSB_LEFR_ARGS(super->hdr.fsid, fence_rid),
+				     SCSB_LEFR_ARGS(lefsid, fence_rid),
 				     le64_to_cpu(old[i][j].term), i, SIN_ARG(&sin));
 			ret = scoutfs_fence_start(sb, le64_to_cpu(fence_rid), sin.sin_addr.s_addr,
 						  SCOUTFS_FENCE_QUORUM_BLOCK_LEADER);
@@ -752,7 +759,7 @@ static void scoutfs_quorum_worker(struct work_struct *work)
 
 			qst.server_start_term = qst.term;
 			qst.server_event = SCOUTFS_QUORUM_EVENT_ELECT;
-			scoutfs_server_start(sb, qst.term);
+			scoutfs_server_start(sb, &qinf->qconf, qst.term);
 		}
 
 		/*
@@ -877,16 +884,25 @@ out:
  */
 int scoutfs_quorum_server_sin(struct super_block *sb, struct sockaddr_in *sin)
 {
-	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &sbi->super;
+	struct scoutfs_super_block *super = NULL;
 	struct scoutfs_quorum_block blk;
 	u64 elect_term;
 	u64 term = 0;
 	int ret = 0;
 	int i;
 
+	super = kmalloc(sizeof(struct scoutfs_super_block), GFP_NOFS);
+	if (!super) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = scoutfs_read_super(sb, super);
+	if (ret)
+		goto out;
+
 	for (i = 0; i < SCOUTFS_QUORUM_MAX_SLOTS; i++) {
-		if (!quorum_slot_present(super, i))
+		if (!quorum_slot_present(&super->qconf, i))
 			continue;
 
 		ret = read_quorum_block(sb, SCOUTFS_QUORUM_BLKNO + i, &blk, false);
@@ -900,7 +916,7 @@ int scoutfs_quorum_server_sin(struct super_block *sb, struct sockaddr_in *sin)
 		if (elect_term > term &&
 		    elect_term > le64_to_cpu(blk.events[SCOUTFS_QUORUM_EVENT_STOP].term)) {
 			term = elect_term;
-			scoutfs_quorum_slot_sin(super, i, sin);
+			scoutfs_quorum_slot_sin(&super->qconf, i, sin);
 			continue;
 		}
 	}
@@ -909,6 +925,7 @@ int scoutfs_quorum_server_sin(struct super_block *sb, struct sockaddr_in *sin)
 		ret = -ENOENT;
 
 out:
+	kfree(super);
 	return ret;
 }
 
@@ -924,12 +941,9 @@ u8 scoutfs_quorum_votes_needed(struct super_block *sb)
 	return qinf->votes_needed;
 }
 
-void scoutfs_quorum_slot_sin(struct scoutfs_super_block *super, int i,
-			     struct sockaddr_in *sin)
+void scoutfs_quorum_slot_sin(struct scoutfs_quorum_config *qconf, int i, struct sockaddr_in *sin)
 {
-	BUG_ON(i < 0 || i >= SCOUTFS_QUORUM_MAX_SLOTS);
-
-	scoutfs_addr_to_sin(sin, &super->qconf.slots[i].addr);
+	return quorum_slot_sin(qconf, i, sin);
 }
 
 static char *role_str(int role)
@@ -1060,11 +1074,10 @@ static inline bool valid_ipv4_port(__be16 port)
 	return port != 0 && be16_to_cpu(port) != U16_MAX;
 }
 
-static int verify_quorum_slots(struct super_block *sb)
+static int verify_quorum_slots(struct super_block *sb, struct quorum_info *qinf,
+			       struct scoutfs_quorum_config *qconf)
 {
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
 	char slots[(SCOUTFS_QUORUM_MAX_SLOTS * 3) + 1];
-	DECLARE_QUORUM_INFO(sb, qinf);
 	struct sockaddr_in other;
 	struct sockaddr_in sin;
 	int found = 0;
@@ -1074,10 +1087,10 @@ static int verify_quorum_slots(struct super_block *sb)
 
 
 	for (i = 0; i < SCOUTFS_QUORUM_MAX_SLOTS; i++) {
-		if (!quorum_slot_present(super, i))
+		if (!quorum_slot_present(qconf, i))
 			continue;
 
-		scoutfs_quorum_slot_sin(super, i, &sin);
+		scoutfs_quorum_slot_sin(qconf, i, &sin);
 
 		if (!valid_ipv4_unicast(sin.sin_addr.s_addr)) {
 			scoutfs_err(sb, "quorum slot #%d has invalid ipv4 unicast address: "SIN_FMT,
@@ -1092,10 +1105,10 @@ static int verify_quorum_slots(struct super_block *sb)
 		}
 
 		for (j = i + 1; j < SCOUTFS_QUORUM_MAX_SLOTS; j++) {
-			if (!quorum_slot_present(super, j))
+			if (!quorum_slot_present(qconf, j))
 				continue;
 
-			scoutfs_quorum_slot_sin(super, j, &other);
+			scoutfs_quorum_slot_sin(qconf, j, &other);
 
 			if (sin.sin_addr.s_addr == other.sin_addr.s_addr &&
 			    sin.sin_port == other.sin_port) {
@@ -1113,11 +1126,11 @@ static int verify_quorum_slots(struct super_block *sb)
 		return -EINVAL;
 	}
 
-	if (!quorum_slot_present(super, qinf->our_quorum_slot_nr)) {
+	if (!quorum_slot_present(qconf, qinf->our_quorum_slot_nr)) {
 		char *str = slots;
 		*str = '\0';
 		for (i = 0; i < SCOUTFS_QUORUM_MAX_SLOTS; i++) {
-			if (quorum_slot_present(super, i)) {
+			if (quorum_slot_present(qconf, i)) {
 				ret = snprintf(str, &slots[ARRAY_SIZE(slots)] - str, "%c%u",
 					       str == slots ? ' ' : ',', i);
 				if (ret < 2 || ret > 3) {
@@ -1141,16 +1154,22 @@ static int verify_quorum_slots(struct super_block *sb)
 	else
 		qinf->votes_needed = (found / 2) + 1;
 
+	qinf->qconf = *qconf;
+
 	return 0;
 }
 
 /*
  * Once this schedules the quorum worker it can be elected leader and
- * start the server, possibly before this returns.
+ * start the server, possibly before this returns.  The quorum agent
+ * would be responsible for tracking the quorum config in the super
+ * block if it changes.  Until then uses a static config that it reads
+ * during setup.
  */
 int scoutfs_quorum_setup(struct super_block *sb)
 {
 	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
+	struct scoutfs_super_block *super = NULL;
 	struct scoutfs_mount_options opts;
 	struct quorum_info *qinf;
 	int ret;
@@ -1160,7 +1179,9 @@ int scoutfs_quorum_setup(struct super_block *sb)
 		return 0;
 
 	qinf = kzalloc(sizeof(struct quorum_info), GFP_KERNEL);
-	if (!qinf) {
+	super = kmalloc(sizeof(struct scoutfs_super_block), GFP_KERNEL);
+	if (!qinf || !super) {
+		kfree(qinf);
 		ret = -ENOMEM;
 		goto out;
 	}
@@ -1174,7 +1195,11 @@ int scoutfs_quorum_setup(struct super_block *sb)
 	sbi->quorum_info = qinf;
 	qinf->sb = sb;
 
-	ret = verify_quorum_slots(sb);
+	ret = scoutfs_read_super(sb, super);
+	if (ret < 0)
+		goto out;
+
+	ret = verify_quorum_slots(sb, qinf, &super->qconf);
 	if (ret < 0)
 		goto out;
 
@@ -1194,6 +1219,7 @@ out:
 	if (ret)
 		scoutfs_quorum_destroy(sb);
 
+	kfree(super);
 	return ret;
 }
 

kmod/src/quorum.h

@@ -4,10 +4,11 @@
 int scoutfs_quorum_server_sin(struct super_block *sb, struct sockaddr_in *sin);
 
 u8 scoutfs_quorum_votes_needed(struct super_block *sb);
-void scoutfs_quorum_slot_sin(struct scoutfs_super_block *super, int i,
+void scoutfs_quorum_slot_sin(struct scoutfs_quorum_config *qconf, int i,
 			     struct sockaddr_in *sin);
 
-int scoutfs_quorum_fence_leaders(struct super_block *sb, u64 term);
+int scoutfs_quorum_fence_leaders(struct super_block *sb, struct scoutfs_quorum_config *qconf,
+				 u64 term);
 
 int scoutfs_quorum_setup(struct super_block *sb);
 void scoutfs_quorum_shutdown(struct super_block *sb);

kmod/src/server.c

@@ -130,9 +130,9 @@ struct server_info {
 	struct mutex srch_mutex;
 	struct mutex mounted_clients_mutex;
 
-	/* stable versions stored from commits, given in locks and rpcs */
-	seqcount_t roots_seqcount;
-	struct scoutfs_net_roots roots;
+	/* stable super stored from commits, given in locks and rpcs */
+	seqcount_t stable_seqcount;
+	struct scoutfs_super_block stable_super;
 
 	/* serializing and get and set volume options */
 	seqcount_t volopt_seqcount;
@@ -143,11 +143,18 @@ struct server_info {
 	struct work_struct fence_pending_recov_work;
 	/* while running we check for fenced mounts to reclaim */
 	struct delayed_work reclaim_dwork;
+
+	/* a running server gets a static quorum config from quorum as it starts */
+	struct scoutfs_quorum_config qconf;
+	/* a running server maintains a private dirty super */
+	struct scoutfs_super_block dirty_super;
 };
 
 #define DECLARE_SERVER_INFO(sb, name) \
 	struct server_info *name = SCOUTFS_SB(sb)->server_info
 
+#define DIRTY_SUPER_SB(sb)	(&SCOUTFS_SB(sb)->server_info->dirty_super)
+
 /*
  * The server tracks each connected client.
  */
@@ -469,16 +476,22 @@ static void commit_end(struct super_block *sb, struct commit_users *cusers, int
 	wake_up(&cusers->waitq);
 }
 
-static void get_roots(struct super_block *sb,
-			      struct scoutfs_net_roots *roots)
+static void get_stable(struct super_block *sb, struct scoutfs_super_block *super,
+		       struct scoutfs_net_roots *roots)
 {
 	DECLARE_SERVER_INFO(sb, server);
 	unsigned int seq;
 
 	do {
-		seq = read_seqcount_begin(&server->roots_seqcount);
-		*roots = server->roots;
-	} while (read_seqcount_retry(&server->roots_seqcount, seq));
+		seq = read_seqcount_begin(&server->stable_seqcount);
+		if (super)
+			*super = server->stable_super;
+		if (roots) {
+			roots->fs_root = server->stable_super.fs_root;
+			roots->logs_root = server->stable_super.logs_root;
+			roots->srch_root = server->stable_super.srch_root;
+		}
+	} while (read_seqcount_retry(&server->stable_seqcount, seq));
 }
 
 u64 scoutfs_server_seq(struct super_block *sb)
@@ -510,17 +523,12 @@ void scoutfs_server_set_seq_if_greater(struct super_block *sb, u64 seq)
 	}
 }
 
-static void set_roots(struct server_info *server,
-		      struct scoutfs_btree_root *fs_root,
-		      struct scoutfs_btree_root *logs_root,
-		      struct scoutfs_btree_root *srch_root)
+static void set_stable_super(struct server_info *server, struct scoutfs_super_block *super)
 {
 	preempt_disable();
-	write_seqcount_begin(&server->roots_seqcount);
-	server->roots.fs_root = *fs_root;
-	server->roots.logs_root = *logs_root;
-	server->roots.srch_root = *srch_root;
-	write_seqcount_end(&server->roots_seqcount);
+	write_seqcount_begin(&server->stable_seqcount);
+	server->stable_super = *super;
+	write_seqcount_end(&server->stable_seqcount);
 	preempt_enable();
 }
 
@@ -545,7 +553,7 @@ static void scoutfs_server_commit_func(struct work_struct *work)
 	struct server_info *server = container_of(work, struct server_info,
 						  commit_work);
 	struct super_block *sb = server->sb;
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct commit_users *cusers = &server->cusers;
 	int ret;
 
@@ -603,8 +611,7 @@ static void scoutfs_server_commit_func(struct work_struct *work)
 		goto out;
 	}
 
-	set_roots(server, &super->fs_root, &super->logs_root,
-		  &super->srch_root);
+	set_stable_super(server, super);
 
 	/* swizzle the active and idle server alloc/freed heads */
 	server->other_ind ^= 1;
@@ -641,7 +648,7 @@ static int server_alloc_inodes(struct super_block *sb,
 			       u8 cmd, u64 id, void *arg, u16 arg_len)
 {
 	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &sbi->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_net_inode_alloc ial = { 0, };
 	COMMIT_HOLD(hold);
 	__le64 lecount;
@@ -809,7 +816,7 @@ static void mod_bitmap_bits(__le64 *dst, u64 dst_zone_blocks,
 static int get_data_alloc_zone_bits(struct super_block *sb, u64 rid, __le64 *exclusive,
 				    __le64 *vacant, u64 zone_blocks)
 {
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	SCOUTFS_BTREE_ITEM_REF(iref);
 	struct scoutfs_log_trees *lt;
 	struct scoutfs_key key;
@@ -1040,7 +1047,7 @@ static int finalize_and_start_log_merge(struct super_block *sb, struct scoutfs_l
 					u64 rid, struct commit_hold *hold)
 {
 	struct server_info *server = SCOUTFS_SB(sb)->server_info;
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_log_merge_status stat;
 	struct scoutfs_log_merge_range rng;
 	struct scoutfs_log_trees each_lt;
@@ -1242,7 +1249,7 @@ static int finalize_and_start_log_merge(struct super_block *sb, struct scoutfs_l
 static void try_drain_data_freed(struct super_block *sb, struct scoutfs_log_trees *lt)
 {
 	DECLARE_SERVER_INFO(sb, server);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	const u64 rid = le64_to_cpu(lt->rid);
 	const u64 nr = le64_to_cpu(lt->nr);
 	struct scoutfs_log_trees drain;
@@ -1329,7 +1336,7 @@ static int server_get_log_trees(struct super_block *sb,
 				struct scoutfs_net_connection *conn,
 				u8 cmd, u64 id, void *arg, u16 arg_len)
 {
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	u64 rid = scoutfs_net_client_rid(conn);
 	DECLARE_SERVER_INFO(sb, server);
 	__le64 exclusive[SCOUTFS_DATA_ALLOC_ZONE_LE64S];
@@ -1524,7 +1531,7 @@ static int server_commit_log_trees(struct super_block *sb,
 				   struct scoutfs_net_connection *conn,
 				   u8 cmd, u64 id, void *arg, u16 arg_len)
 {
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	const u64 rid = scoutfs_net_client_rid(conn);
 	DECLARE_SERVER_INFO(sb, server);
 	SCOUTFS_BTREE_ITEM_REF(iref);
@@ -1624,7 +1631,7 @@ static int server_get_roots(struct super_block *sb,
 		memset(&roots, 0, sizeof(roots));
 		ret = -EINVAL;
 	}  else {
-		get_roots(sb, &roots);
+		get_stable(sb, NULL, &roots);
 		ret = 0;
 	}
 
@@ -1654,7 +1661,7 @@ static int server_get_roots(struct super_block *sb,
  */
 static int reclaim_open_log_tree(struct super_block *sb, u64 rid)
 {
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	DECLARE_SERVER_INFO(sb, server);
 	SCOUTFS_BTREE_ITEM_REF(iref);
 	struct scoutfs_log_trees lt;
@@ -1751,9 +1758,8 @@ out:
  */
 static int get_stable_trans_seq(struct super_block *sb, u64 *last_seq_ret)
 {
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	DECLARE_SERVER_INFO(sb, server);
-	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &sbi->super;
 	SCOUTFS_BTREE_ITEM_REF(iref);
 	struct scoutfs_log_trees *lt;
 	struct scoutfs_key key;
@@ -1909,9 +1915,8 @@ static int server_srch_get_compact(struct super_block *sb,
 				   u8 cmd, u64 id, void *arg, u16 arg_len)
 {
 	DECLARE_SERVER_INFO(sb, server);
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	u64 rid = scoutfs_net_client_rid(conn);
-	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &sbi->super;
 	struct scoutfs_srch_compact *sc = NULL;
 	COMMIT_HOLD(hold);
 	int ret;
@@ -1976,8 +1981,7 @@ static int server_srch_commit_compact(struct super_block *sb,
 {
 	DECLARE_SERVER_INFO(sb, server);
 	u64 rid = scoutfs_net_client_rid(conn);
-	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &sbi->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_srch_compact *sc;
 	struct scoutfs_alloc_list_head av;
 	struct scoutfs_alloc_list_head fr;
@@ -2052,8 +2056,7 @@ static int splice_log_merge_completions(struct super_block *sb,
 					bool no_ranges)
 {
 	struct server_info *server = SCOUTFS_SB(sb)->server_info;
-	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &sbi->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_log_merge_complete comp;
 	struct scoutfs_log_merge_freeing fr;
 	struct scoutfs_log_merge_range rng;
@@ -2370,7 +2373,7 @@ static void server_log_merge_free_work(struct work_struct *work)
 	struct server_info *server = container_of(work, struct server_info,
 						  log_merge_free_work);
 	struct super_block *sb = server->sb;
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_log_merge_freeing fr;
 	struct scoutfs_key key;
 	COMMIT_HOLD(hold);
@@ -2462,8 +2465,7 @@ static int server_get_log_merge(struct super_block *sb,
 {
 	DECLARE_SERVER_INFO(sb, server);
 	u64 rid = scoutfs_net_client_rid(conn);
-	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &sbi->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_log_merge_status stat;
 	struct scoutfs_log_merge_range rng;
 	struct scoutfs_log_merge_range remain;
@@ -2746,8 +2748,7 @@ static int server_commit_log_merge(struct super_block *sb,
 {
 	DECLARE_SERVER_INFO(sb, server);
 	u64 rid = scoutfs_net_client_rid(conn);
-	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &sbi->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_log_merge_request orig_req;
 	struct scoutfs_log_merge_complete *comp;
 	struct scoutfs_log_merge_status stat;
@@ -2982,7 +2983,7 @@ static int server_set_volopt(struct super_block *sb, struct scoutfs_net_connecti
 			     u8 cmd, u64 id, void *arg, u16 arg_len)
 {
 	DECLARE_SERVER_INFO(sb, server);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_volume_options *volopt;
 	COMMIT_HOLD(hold);
 	u64 opt;
@@ -3051,7 +3052,7 @@ static int server_clear_volopt(struct super_block *sb, struct scoutfs_net_connec
 			       u8 cmd, u64 id, void *arg, u16 arg_len)
 {
 	DECLARE_SERVER_INFO(sb, server);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_volume_options *volopt;
 	COMMIT_HOLD(hold);
 	__le64 *opt;
@@ -3105,7 +3106,7 @@ static int server_resize_devices(struct super_block *sb, struct scoutfs_net_conn
 {
 	DECLARE_SERVER_INFO(sb, server);
 	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_net_resize_devices *nrd;
 	COMMIT_HOLD(hold);
 	u64 meta_tot;
@@ -3212,16 +3213,19 @@ static int count_free_blocks(struct super_block *sb, void *arg, int owner,
 }
 
 /*
- * We calculate the total inode count and free blocks from the current in-memory dirty
- * versions of the super block and log_trees structs, so we have to lock them.
+ * We calculate the total inode count and free blocks from the last
+ * stable super that was written.  Other users also walk stable blocks
+ * so by joining them we don't have to worry about ensuring that we've
+ * locked all the dirty structures that the summations could reference.
+ * We handle stale reads by retrying with the most recent stable super.
  */
 static int server_statfs(struct super_block *sb, struct scoutfs_net_connection *conn,
 			 u8 cmd, u64 id, void *arg, u16 arg_len)
 {
-	DECLARE_SERVER_INFO(sb, server);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block super;
 	struct scoutfs_net_statfs nst = {{0,}};
 	struct statfs_free_blocks sfb = {0,};
+	DECLARE_SAVED_REFS(saved);
 	u64 inode_count;
 	int ret;
 
@@ -3230,24 +3234,24 @@ static int server_statfs(struct super_block *sb, struct scoutfs_net_connection *
 		goto out;
 	}
 
-	mutex_lock(&server->alloc_mutex);
-	ret = scoutfs_alloc_foreach_super(sb, super, count_free_blocks, &sfb);
-	mutex_unlock(&server->alloc_mutex);
-	if (ret < 0)
-		goto out;
+	do {
+		get_stable(sb, &super, NULL);
 
-	mutex_lock(&server->logs_mutex);
-	ret = scoutfs_forest_inode_count(sb, super, &inode_count);
-	mutex_unlock(&server->logs_mutex);
-	if (ret < 0)
-		goto out;
+		ret = scoutfs_alloc_foreach_super(sb, &super, count_free_blocks, &sfb) ?:
+		      scoutfs_forest_inode_count(sb, &super, &inode_count);
+		if (ret < 0 && ret != -ESTALE)
+			goto out;
 
-	BUILD_BUG_ON(sizeof(nst.uuid) != sizeof(super->uuid));
-	memcpy(nst.uuid, super->uuid, sizeof(nst.uuid));
+		ret = scoutfs_block_check_stale(sb, ret, &saved, &super.logs_root.ref,
+						&super.srch_root.ref);
+	} while (ret == -ESTALE);
+
+	BUILD_BUG_ON(sizeof(nst.uuid) != sizeof(super.uuid));
+	memcpy(nst.uuid, super.uuid, sizeof(nst.uuid));
 	nst.free_meta_blocks = cpu_to_le64(sfb.meta);
-	nst.total_meta_blocks = super->total_meta_blocks;
+	nst.total_meta_blocks = super.total_meta_blocks;
 	nst.free_data_blocks = cpu_to_le64(sfb.data);
-	nst.total_data_blocks = super->total_data_blocks;
+	nst.total_data_blocks = super.total_data_blocks;
 	nst.inode_count = cpu_to_le64(inode_count);
 
 	ret = 0;
@@ -3278,7 +3282,7 @@ static int insert_mounted_client(struct super_block *sb, u64 rid, u64 gr_flags,
 				 struct sockaddr_in *sin)
 {
 	DECLARE_SERVER_INFO(sb, server);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_mounted_client_btree_val mcv;
 	struct scoutfs_key key;
 	int ret;
@@ -3304,7 +3308,7 @@ static int lookup_mounted_client_addr(struct super_block *sb, u64 rid,
 				      union scoutfs_inet_addr *addr)
 {
 	DECLARE_SERVER_INFO(sb, server);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_mounted_client_btree_val *mcv;
 	SCOUTFS_BTREE_ITEM_REF(iref);
 	struct scoutfs_key key;
@@ -3338,7 +3342,7 @@ static int lookup_mounted_client_addr(struct super_block *sb, u64 rid,
 static int delete_mounted_client(struct super_block *sb, u64 rid)
 {
 	DECLARE_SERVER_INFO(sb, server);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_key key;
 	int ret;
 
@@ -3362,7 +3366,7 @@ static int delete_mounted_client(struct super_block *sb, u64 rid)
 static int cancel_srch_compact(struct super_block *sb, u64 rid)
 {
 	DECLARE_SERVER_INFO(sb, server);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_alloc_list_head av;
 	struct scoutfs_alloc_list_head fr;
 	int ret;
@@ -3414,7 +3418,7 @@ static int cancel_srch_compact(struct super_block *sb, u64 rid)
 static int cancel_log_merge(struct super_block *sb, u64 rid)
 {
 	DECLARE_SERVER_INFO(sb, server);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_log_merge_status stat;
 	struct scoutfs_log_merge_request req;
 	struct scoutfs_log_merge_range rng;
@@ -3538,7 +3542,7 @@ static int server_greeting(struct super_block *sb,
 			   u8 cmd, u64 id, void *arg, u16 arg_len)
 {
 	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &sbi->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_net_greeting *gr = arg;
 	struct scoutfs_net_greeting greet;
 	DECLARE_SERVER_INFO(sb, server);
@@ -3554,10 +3558,9 @@ static int server_greeting(struct super_block *sb,
 		goto send_err;
 	}
 
-	if (gr->fsid != super->hdr.fsid) {
+	if (gr->fsid != cpu_to_le64(sbi->fsid)) {
 		scoutfs_warn(sb, "client rid %016llx greeting fsid 0x%llx did not match server fsid 0x%llx",
-			     le64_to_cpu(gr->rid), le64_to_cpu(gr->fsid),
-			     le64_to_cpu(super->hdr.fsid));
+			     le64_to_cpu(gr->rid), le64_to_cpu(gr->fsid), sbi->fsid);
 		ret = -EINVAL;
 		goto send_err;
 	}
@@ -3697,7 +3700,7 @@ static void farewell_worker(struct work_struct *work)
 	struct server_info *server = container_of(work, struct server_info,
 						  farewell_work);
 	struct super_block *sb = server->sb;
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_mounted_client_btree_val *mcv;
 	struct farewell_request *tmp;
 	struct farewell_request *fw;
@@ -4059,7 +4062,7 @@ static void recovery_timeout(struct super_block *sb)
 static int start_recovery(struct super_block *sb)
 {
 	DECLARE_SERVER_INFO(sb, server);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	SCOUTFS_BTREE_ITEM_REF(iref);
 	struct scoutfs_key key;
 	unsigned int nr = 0;
@@ -4176,8 +4179,7 @@ static void scoutfs_server_worker(struct work_struct *work)
 	struct server_info *server = container_of(work, struct server_info,
 						  work);
 	struct super_block *sb = server->sb;
-	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
-	struct scoutfs_super_block *super = &sbi->super;
+	struct scoutfs_super_block *super = DIRTY_SUPER_SB(sb);
 	struct scoutfs_net_connection *conn = NULL;
 	struct scoutfs_mount_options opts;
 	DECLARE_WAIT_QUEUE_HEAD(waitq);
@@ -4189,13 +4191,13 @@ static void scoutfs_server_worker(struct work_struct *work)
 	trace_scoutfs_server_work_enter(sb, 0, 0);
 
 	scoutfs_options_read(sb, &opts);
-	scoutfs_quorum_slot_sin(super, opts.quorum_slot_nr, &sin);
+	scoutfs_quorum_slot_sin(&server->qconf, opts.quorum_slot_nr, &sin);
 	scoutfs_info(sb, "server starting at "SIN_FMT, SIN_ARG(&sin));
 
 	scoutfs_block_writer_init(sb, &server->wri);
 
 	/* first make sure no other servers are still running */
-	ret = scoutfs_quorum_fence_leaders(sb, server->term);
+	ret = scoutfs_quorum_fence_leaders(sb, &server->qconf, server->term);
 	if (ret < 0) {
 		scoutfs_err(sb, "server error %d attempting to fence previous leaders", ret);
 		goto out;
@@ -4231,8 +4233,7 @@ static void scoutfs_server_worker(struct work_struct *work)
 	write_seqcount_end(&server->volopt_seqcount);
 
 	atomic64_set(&server->seq_atomic, le64_to_cpu(super->seq));
-	set_roots(server, &super->fs_root, &super->logs_root,
-		  &super->srch_root);
+	set_stable_super(server, super);
 
 	/* prepare server alloc for this transaction, larger first */
 	if (le64_to_cpu(super->server_meta_avail[0].total_nr) <
@@ -4326,11 +4327,12 @@ out:
 /*
  * Start the server but don't wait for it to complete.
  */
-void scoutfs_server_start(struct super_block *sb, u64 term)
+void scoutfs_server_start(struct super_block *sb, struct scoutfs_quorum_config *qconf, u64 term)
 {
 	DECLARE_SERVER_INFO(sb, server);
 
 	if (cmpxchg(&server->status, SERVER_DOWN, SERVER_STARTING) == SERVER_DOWN) {
+		server->qconf = *qconf;
 		server->term = term;
 		queue_work(server->wq, &server->work);
 	}
@@ -4382,7 +4384,7 @@ int scoutfs_server_setup(struct super_block *sb)
 	INIT_WORK(&server->log_merge_free_work, server_log_merge_free_work);
 	mutex_init(&server->srch_mutex);
 	mutex_init(&server->mounted_clients_mutex);
-	seqcount_init(&server->roots_seqcount);
+	seqcount_init(&server->stable_seqcount);
 	seqcount_init(&server->volopt_seqcount);
 	mutex_init(&server->volopt_mutex);
 	INIT_WORK(&server->fence_pending_recov_work, fence_pending_recov_worker);

kmod/src/server.h

@@ -75,7 +75,7 @@ u64 scoutfs_server_seq(struct super_block *sb);
 u64 scoutfs_server_next_seq(struct super_block *sb);
 void scoutfs_server_set_seq_if_greater(struct super_block *sb, u64 seq);
 
-void scoutfs_server_start(struct super_block *sb, u64 term);
+void scoutfs_server_start(struct super_block *sb, struct scoutfs_quorum_config *qconf, u64 term);
 void scoutfs_server_stop(struct super_block *sb);
 void scoutfs_server_stop_wait(struct super_block *sb);
 bool scoutfs_server_is_running(struct super_block *sb);

kmod/src/srch.c

@@ -861,7 +861,6 @@ int scoutfs_srch_search_xattrs(struct super_block *sb,
 			       struct scoutfs_srch_rb_root *sroot,
 			       u64 hash, u64 ino, u64 last_ino, bool *done)
 {
-	struct scoutfs_net_roots prev_roots;
 	struct scoutfs_net_roots roots;
 	struct scoutfs_srch_entry start;
 	struct scoutfs_srch_entry end;
@@ -869,6 +868,7 @@ int scoutfs_srch_search_xattrs(struct super_block *sb,
 	struct scoutfs_log_trees lt;
 	struct scoutfs_srch_file sfl;
 	SCOUTFS_BTREE_ITEM_REF(iref);
+	DECLARE_SAVED_REFS(saved);
 	struct scoutfs_key key;
 	unsigned long limit = SRCH_LIMIT;
 	int ret;
@@ -877,7 +877,6 @@ int scoutfs_srch_search_xattrs(struct super_block *sb,
 
 	*done = false;
 	srch_init_rb_root(sroot);
-	memset(&prev_roots, 0, sizeof(prev_roots));
 
 	start.hash = cpu_to_le64(hash);
 	start.ino = cpu_to_le64(ino);
@@ -892,7 +891,6 @@ retry:
 	ret = scoutfs_client_get_roots(sb, &roots);
 	if (ret)
 		goto out;
-	memset(&roots.fs_root, 0, sizeof(roots.fs_root));
 
 	end = final;
 
@@ -968,16 +966,10 @@ retry:
 	*done = sre_cmp(&end, &final) == 0;
 	ret = 0;
 out:
-	if (ret == -ESTALE) {
-		if (memcmp(&prev_roots, &roots, sizeof(roots)) == 0) {
-			scoutfs_inc_counter(sb, srch_search_stale_eio);
-			ret = -EIO;
-		} else {
-			scoutfs_inc_counter(sb, srch_search_stale_retry);
-			prev_roots = roots;
-			goto retry;
-		}
-	}
+	ret = scoutfs_block_check_stale(sb, ret, &saved, &roots.srch_root.ref,
+					&roots.logs_root.ref);
+	if (ret == -ESTALE)
+		goto retry;
 
 	return ret;
 }

kmod/src/super.c

@@ -461,9 +461,8 @@ static int scoutfs_read_supers(struct super_block *sb)
 		goto out;
 	}
 
-
+	sbi->fsid = le64_to_cpu(meta_super->hdr.fsid);
 	sbi->fmt_vers = le64_to_cpu(meta_super->fmt_vers);
-	sbi->super = *meta_super;
 out:
 	kfree(meta_super);
 	kfree(data_super);

kmod/src/super.h

@@ -35,11 +35,10 @@ struct scoutfs_sb_info {
 	struct super_block *sb;
 
 	/* assigned once at the start of each mount, read-only */
+	u64 fsid;
 	u64 rid;
 	u64 fmt_vers;
 
-	struct scoutfs_super_block super;
-
 	struct block_device *meta_bdev;
 
 	spinlock_t next_ino_lock;
@@ -135,14 +134,14 @@ static inline bool scoutfs_unmounting(struct super_block *sb)
 	(int)(le64_to_cpu(fsid) >> SCSB_SHIFT),				    \
 	(int)(le64_to_cpu(rid) >> SCSB_SHIFT)
 #define SCSB_ARGS(sb)							    \
-	(int)(le64_to_cpu(SCOUTFS_SB(sb)->super.hdr.fsid) >> SCSB_SHIFT),   \
+	(int)(SCOUTFS_SB(sb)->fsid >> SCSB_SHIFT),			    \
 	(int)(SCOUTFS_SB(sb)->rid >> SCSB_SHIFT)
 #define SCSB_TRACE_FIELDS	\
 	__field(__u64, fsid)	\
 	__field(__u64, rid)
 #define SCSB_TRACE_ASSIGN(sb)						\
 	__entry->fsid = SCOUTFS_HAS_SBI(sb) ?				\
-			le64_to_cpu(SCOUTFS_SB(sb)->super.hdr.fsid) : 0;\
+		        SCOUTFS_SB(sb)->fsid : 0;			\
 	__entry->rid = SCOUTFS_HAS_SBI(sb) ?				\
 		       SCOUTFS_SB(sb)->rid : 0;
 #define SCSB_TRACE_ARGS				\

kmod/src/sysfs.c

@@ -60,10 +60,9 @@ static ssize_t fsid_show(struct kobject *kobj, struct attribute *attr,
 			 char *buf)
 {
 	struct super_block *sb = KOBJ_TO_SB(kobj, sb_id_kobj);
-	struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
+	struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
 
-	return snprintf(buf, PAGE_SIZE, "%016llx\n",
-			le64_to_cpu(super->hdr.fsid));
+	return snprintf(buf, PAGE_SIZE, "%016llx\n", sbi->fsid);
 }
 ATTR_FUNCS_RO(fsid);