cephfs-journal-tool: get and check layout info during dump/undump

when cephfs-journal-tool import journal, it uses default layout
to get object_size, this is wrong. Because default objetct_size
can be changed by Config option change mds_log_segment_size when
cluster initialized.

The fix is save the layout info to header during journal export,
When improt journal, first try to get layout from cluster, if failed,
then get layout info from dumped journal file, if still failed, set
layout to default.

Fixes: http://tracker.ceph.com/issues/24644

Signed-off-by: Gu Zhongyan <guzhongyan@360.cn>
Signed-off-by: yupeng chen chenyupeng-it@360.cn

src/tools/cephfs/Dumper.cc

@@ -108,13 +108,19 @@ int Dumper::dump(const char *dump_file)
     // include an informative header
     char buf[HEADER_LEN];
     memset(buf, 0, sizeof(buf));
-    snprintf(buf, HEADER_LEN, "Ceph mds%d journal dump\n start offset %llu (0x%llx)\n       length %llu (0x%llx)\n    write_pos %llu (0x%llx)\n    format %llu\n    trimmed_pos %llu (0x%llx)\n%c",
+    snprintf(buf, HEADER_LEN, "Ceph mds%d journal dump\n start offset %llu (0x%llx)\n\
+       length %llu (0x%llx)\n    write_pos %llu (0x%llx)\n    format %llu\n\
+    trimmed_pos %llu (0x%llx)\n    stripe_unit %lu (0x%lx)\n    stripe_count %lu (0x%lx)\n\
+    object_size %lu (0x%lx)\n    fsid %s\n%c",
 	    role.rank, 
 	    (unsigned long long)start, (unsigned long long)start,
 	    (unsigned long long)len, (unsigned long long)len,
 	    (unsigned long long)journaler.last_committed.write_pos, (unsigned long long)journaler.last_committed.write_pos,
 	    (unsigned long long)journaler.last_committed.stream_format,
 	    (unsigned long long)journaler.last_committed.trimmed_pos, (unsigned long long)journaler.last_committed.trimmed_pos,
+            (unsigned long)journaler.last_committed.layout.stripe_unit, (unsigned long)journaler.last_committed.layout.stripe_unit,
+            (unsigned long)journaler.last_committed.layout.stripe_count, (unsigned long)journaler.last_committed.layout.stripe_count,
+            (unsigned long)journaler.last_committed.layout.object_size, (unsigned long)journaler.last_committed.layout.object_size,
 	    4);
     r = safe_write(fd, buf, sizeof(buf));
     if (r) {
@@ -193,6 +199,15 @@ int Dumper::undump(const char *dump_file)
   assert(fs != nullptr);
 
   int r = 0;
+  // try get layout info from cluster
+  Journaler journaler("umdumper", ino, fs->mds_map.get_metadata_pool(),
+                      CEPH_FS_ONDISK_MAGIC, objecter, 0, 0,
+                      &finisher);
+  int recovered = recover_journal(&journaler);
+  if (recovered != 0) {
+    derr << "recover_journal failed, try to get header from dump file " << dendl;
+  }
+
   int fd = ::open(dump_file, O_RDONLY);
   if (fd < 0) {
     r = errno;
@@ -212,16 +227,41 @@ int Dumper::undump(const char *dump_file)
   }
 
   long long unsigned start, len, write_pos, format, trimmed_pos;
+  long unsigned stripe_unit, stripe_count, object_size;
   sscanf(strstr(buf, "start offset"), "start offset %llu", &start);
   sscanf(strstr(buf, "length"), "length %llu", &len);
   sscanf(strstr(buf, "write_pos"), "write_pos %llu", &write_pos);
   sscanf(strstr(buf, "format"), "format %llu", &format);
+  if (recovered == 0) {
+    stripe_unit = journaler.last_committed.layout.stripe_unit;
+    stripe_count = journaler.last_committed.layout.stripe_count;
+    object_size = journaler.last_committed.layout.object_size;
+  } else {
+    // try to get layout from dump file header, if failed set layout to default
+    if (strstr(buf, "stripe_unit")) {
+      sscanf(strstr(buf, "stripe_unit"), "stripe_unit %lu", &stripe_unit);
+    } else {
+      stripe_unit = file_layout_t::get_default().stripe_unit;
+    }
+    if (strstr(buf, "stripe_count")) {
+      sscanf(strstr(buf, "stripe_count"), "stripe_count %lu", &stripe_count);
+    } else {
+      stripe_count = file_layout_t::get_default().stripe_count;
+    }
+    if (strstr(buf, "object_size")) {
+      sscanf(strstr(buf, "object_size"), "object_size %lu", &object_size);
+    } else {
+      object_size = file_layout_t::get_default().object_size;
+    }
+  }
+
+
   if (strstr(buf, "trimmed_pos")) {
     sscanf(strstr(buf, "trimmed_pos"), "trimmed_pos %llu", &trimmed_pos);
   } else {
     // Old format dump, any untrimmed objects before expire_pos will
     // be discarded as trash.
-    trimmed_pos = start - (start % file_layout_t::get_default().object_size);
+    trimmed_pos = start - (start % object_size);
   }
 
   if (trimmed_pos > start) {
@@ -242,7 +282,10 @@ int Dumper::undump(const char *dump_file)
     " len " << len <<
     " write_pos " << write_pos <<
     " format " << format <<
-    " trimmed_pos " << trimmed_pos << std::endl;
+    " trimmed_pos " << trimmed_pos <<
+    " stripe_unit " << stripe_unit <<
+    " stripe_count " << stripe_count <<
+    " object_size " << object_size << std::endl;
 
   Journaler::Header h;
   h.trimmed_pos = trimmed_pos;
@@ -251,7 +294,9 @@ int Dumper::undump(const char *dump_file)
   h.stream_format = format;
   h.magic = CEPH_FS_ONDISK_MAGIC;
 
-  h.layout = file_layout_t::get_default();
+  h.layout.stripe_unit = stripe_unit;
+  h.layout.stripe_count = stripe_count;
+  h.layout.object_size = object_size;
   h.layout.pool_id = fs->mds_map.get_metadata_pool();
 
   bufferlist hbl;