[PATCH 4/4 V2] xfsprogs: zero out clean log in xfs_metadump

[Eric Sandeen <sandeen@sandeen.net>]

When doing an obfuscated xfs_metadump, if the log is clean, zero
it out for 2 reasons:

 * It'll make the image more compressible
 * It'll eliminate an un-obfuscated metadata source

If the log isn't clean, and the user expected obfuscation, warn
that metadata in the log will not be obfuscated.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

V2: If not obfuscating, copy log as-is

diff --git a/db/metadump.c b/db/metadump.c
index bea4e00..67de0c5 100644
--- a/db/metadump.c
+++ b/db/metadump.c
@@ -17,6 +17,7 @@
  */
 
 #include <libxfs.h>
+#include <libxlog.h>
 #include "bmap.h"
 #include "command.h"
 #include "metadump.h"
@@ -2169,6 +2170,8 @@ copy_sb_inodes(void)
 static int
 copy_log(void)
 {
+	int dirty;
+
 	if (show_progress)
 		print_progress("Copying log");
 
@@ -2180,6 +2183,36 @@ copy_log(void)
 		print_warning("cannot read log");
 		return !stop_on_read_error;
 	}
+
+	/* If not obfuscating, just copy the log as it is */
+	if (!obfuscate)
+		goto done;
+
+	dirty = xlog_is_dirty(mp, &x, 0);
+
+	switch (dirty) {
+	case 0:
+		/* clear out a clean log */
+		if (show_progress)
+			print_progress("Zeroing clean log");
+		memset(iocur_top->data, 0,
+			mp->m_sb.sb_logblocks * mp->m_sb.sb_blocksize);
+		break;
+	case 1:
+		/* keep the dirty log */
+		if (obfuscate)
+			print_warning(
+_("Filesystem log is dirty; image will contain unobfuscated metadata in log."));
+		break;
+	case -1:
+		/* log detection error */
+		if (obfuscate)
+			print_warning(
+_("Could not discern log; image will contain unobfuscated metadata in log."));
+		break;
+	}
+
+done:
 	return !write_buf(iocur_top);
 }
 

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