Add meta_super_in_use utils helper

Move the code that checks that the super is in use from
change-format-version into its own function in util.c.   We'll use it in
an upcoming command to change the quorum config.

Signed-off-by: Zach Brown <zab@versity.com>

utils/src/change_format_version.c

@@ -45,16 +45,11 @@ static int do_change_fmt_vers(struct change_fmt_vers_args *args)
 {
 	struct scoutfs_super_block *meta_super = NULL;
 	struct scoutfs_super_block *data_super = NULL;
-	struct scoutfs_quorum_block *qblk = NULL;
-	struct scoutfs_quorum_block_event *beg;
-	struct scoutfs_quorum_block_event *end;
 	bool wrote_meta = false;
-	bool in_use = false;
 	char uuid_str[37];
 	int meta_fd = -1;
 	int data_fd = -1;
 	int ret;
-	int i;
 
 	meta_fd = open(args->meta_device, O_DIRECT | O_SYNC | O_RDWR | O_EXCL);
 	if (meta_fd < 0) {
@@ -117,44 +112,13 @@ static int do_change_fmt_vers(struct change_fmt_vers_args *args)
 		goto out;
 	}
 
-	if (meta_super->mounted_clients.ref.blkno != 0) {
-		fprintf(stderr, "meta superblock mounted clients btree is not empty.\n");
-		ret = -EBUSY;
-		in_use = true;
+	ret = meta_super_in_use(meta_fd, meta_super);
+	if (ret < 0) {
+		if (ret == -EBUSY)
+			fprintf(stderr, "The filesystem must be fully recovered and cleanly unmounted to change the format version\n");
 		goto out;
 	}
 
-	/* check for active quorum slots */
-	for (i = 0; i < SCOUTFS_QUORUM_BLOCKS; i++) {
-		if (!quorum_slot_present(meta_super, i))
-			continue;
-		ret = read_block(meta_fd, SCOUTFS_QUORUM_BLKNO + i, SCOUTFS_BLOCK_SM_SHIFT,
-				 (void **)&qblk);
-		if (ret < 0) {
-			fprintf(stderr, "error reading quorum block for slot %u\n", i);
-			goto out;
-		}
-
-		beg = &qblk->events[SCOUTFS_QUORUM_EVENT_BEGIN];
-		end = &qblk->events[SCOUTFS_QUORUM_EVENT_END];
-
-		if (le64_to_cpu(beg->write_nr) > le64_to_cpu(end->write_nr)) {
-			fprintf(stderr, "mount in quorum slot %u could still be running.\n"
-					"  begin event: write_nr %llu timestamp %llu.%08u\n"
-					"    end event: write_nr %llu timestamp %llu.%08u\n",
-				i, le64_to_cpu(beg->write_nr), le64_to_cpu(beg->ts.sec),
-				le32_to_cpu(beg->ts.nsec),
-				le64_to_cpu(end->write_nr), le64_to_cpu(end->ts.sec),
-				le32_to_cpu(end->ts.nsec));
-			ret = -EBUSY;
-			in_use = true;
-			goto out;
-		}
-
-		free(qblk);
-		qblk = NULL;
-	}
-
 	if (le64_to_cpu(meta_super->fmt_vers) != args->fmt_vers) {
 		meta_super->fmt_vers = cpu_to_le64(args->fmt_vers);
 
@@ -195,11 +159,7 @@ static int do_change_fmt_vers(struct change_fmt_vers_args *args)
 		le64_to_cpu(meta_super->fmt_vers));
 
 out:
-	if (in_use)
-		fprintf(stderr, "The filesystem must be fully recovered and cleanly unmounted to change the format version\n");
 
-	if (qblk)
-		free(qblk);
 	if (meta_super)
 		free(meta_super);
 	if (data_super)

utils/src/util.c

@@ -12,6 +12,7 @@
 #include "util.h"
 #include "format.h"
 #include "crc.h"
+#include "quorum.h"
 
 #define ENV_PATH "SCOUTFS_MOUNT_PATH"
 
@@ -201,3 +202,56 @@ int write_block_sync(int fd, u32 magic, __le64 fsid, u64 seq, u64 blkno,
 
 	return 0;
 }
+
+/*
+ * Check to see if the metadata super block indicates that there might
+ * be active mounts using the system.  Returns -errno, 0, or -EBUSY if
+ * we found evidence that the device might be in use.
+ */
+int meta_super_in_use(int meta_fd, struct scoutfs_super_block *meta_super)
+{
+	struct scoutfs_quorum_block *qblk = NULL;
+	struct scoutfs_quorum_block_event *beg;
+	struct scoutfs_quorum_block_event *end;
+	int ret = 0;
+	int i;
+
+	if (meta_super->mounted_clients.ref.blkno != 0) {
+		fprintf(stderr, "meta superblock mounted clients btree is not empty.\n");
+		ret = -EBUSY;
+		goto out;
+	}
+
+	/* check for active quorum slots */
+	for (i = 0; i < SCOUTFS_QUORUM_BLOCKS; i++) {
+		if (!quorum_slot_present(meta_super, i))
+			continue;
+		ret = read_block(meta_fd, SCOUTFS_QUORUM_BLKNO + i, SCOUTFS_BLOCK_SM_SHIFT,
+				 (void **)&qblk);
+		if (ret < 0) {
+			fprintf(stderr, "error reading quorum block for slot %u\n", i);
+			goto out;
+		}
+
+		beg = &qblk->events[SCOUTFS_QUORUM_EVENT_BEGIN];
+		end = &qblk->events[SCOUTFS_QUORUM_EVENT_END];
+
+		if (le64_to_cpu(beg->write_nr) > le64_to_cpu(end->write_nr)) {
+			fprintf(stderr, "mount in quorum slot %u could still be running.\n"
+					"  begin event: write_nr %llu timestamp %llu.%08u\n"
+					"    end event: write_nr %llu timestamp %llu.%08u\n",
+				i, le64_to_cpu(beg->write_nr), le64_to_cpu(beg->ts.sec),
+				le32_to_cpu(beg->ts.nsec),
+				le64_to_cpu(end->write_nr), le64_to_cpu(end->ts.sec),
+				le32_to_cpu(end->ts.nsec));
+			ret = -EBUSY;
+			goto out;
+		}
+
+		free(qblk);
+		qblk = NULL;
+	}
+
+out:
+	return ret;
+}

utils/src/util.h

@@ -117,10 +117,12 @@ int read_block_crc(int fd, u64 blkno, int shift, void **ret_val);
 int read_block_verify(int fd, u32 magic, u64 fsid, u64 blkno, int shift, void **ret_val);
 
 struct scoutfs_block_header;
+struct scoutfs_super_block;
 int write_block(int fd, u32 magic, __le64 fsid, u64 seq, u64 blkno,
 		int shift, struct scoutfs_block_header *hdr);
 int write_block_sync(int fd, u32 magic, __le64 fsid, u64 seq, u64 blkno,
 		     int shift, struct scoutfs_block_header *hdr);
+int meta_super_in_use(int meta_fd, struct scoutfs_super_block *meta_super);
 
 #define __stringify_1(x) #x
 #define __stringify(x) __stringify_1(x)