Btrfs: add fragment=* debug mount option
In tracking down these weird bitmap problems it was helpful to artificially
create an extremely fragmented file system. These mount options let us either
fragment data or metadata or both. With these options I could reproduce all
sorts of weird latencies and hangs that occur under extreme fragmentation and
get them fixed. Thanks,
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index b23d49d..24154e4 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -303,6 +303,9 @@
Opt_commit_interval, Opt_barrier, Opt_nodefrag, Opt_nodiscard,
Opt_noenospc_debug, Opt_noflushoncommit, Opt_acl, Opt_datacow,
Opt_datasum, Opt_treelog, Opt_noinode_cache,
+#ifdef CONFIG_BTRFS_DEBUG
+ Opt_fragment_data, Opt_fragment_metadata, Opt_fragment_all,
+#endif
Opt_err,
};
@@ -355,6 +358,11 @@
{Opt_rescan_uuid_tree, "rescan_uuid_tree"},
{Opt_fatal_errors, "fatal_errors=%s"},
{Opt_commit_interval, "commit=%d"},
+#ifdef CONFIG_BTRFS_DEBUG
+ {Opt_fragment_data, "fragment=data"},
+ {Opt_fragment_metadata, "fragment=metadata"},
+ {Opt_fragment_all, "fragment=all"},
+#endif
{Opt_err, NULL},
};
@@ -721,6 +729,22 @@
info->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
}
break;
+#ifdef CONFIG_BTRFS_DEBUG
+ case Opt_fragment_all:
+ btrfs_info(root->fs_info, "fragmenting all space");
+ btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
+ btrfs_set_opt(info->mount_opt, FRAGMENT_METADATA);
+ break;
+ case Opt_fragment_metadata:
+ btrfs_info(root->fs_info, "fragmenting metadata");
+ btrfs_set_opt(info->mount_opt,
+ FRAGMENT_METADATA);
+ break;
+ case Opt_fragment_data:
+ btrfs_info(root->fs_info, "fragmenting data");
+ btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
+ break;
+#endif
case Opt_err:
btrfs_info(root->fs_info, "unrecognized mount option '%s'", p);
ret = -EINVAL;
@@ -1172,6 +1196,12 @@
seq_puts(seq, ",fatal_errors=panic");
if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
seq_printf(seq, ",commit=%d", info->commit_interval);
+#ifdef CONFIG_BTRFS_DEBUG
+ if (btrfs_test_opt(root, FRAGMENT_DATA))
+ seq_puts(seq, ",fragment=data");
+ if (btrfs_test_opt(root, FRAGMENT_METADATA))
+ seq_puts(seq, ",fragment=metadata");
+#endif
seq_printf(seq, ",subvolid=%llu",
BTRFS_I(d_inode(dentry))->root->root_key.objectid);
seq_puts(seq, ",subvol=");