From 7b82230360d026e375ce67d6d821964f0857c23f Mon Sep 17 00:00:00 2001
From: sobomax <sobomax@FreeBSD.org>
Date: Mon, 18 Jul 2016 05:00:01 +0000
Subject: [PATCH] Relax checking if the privider size matches size recorded in
 the superblock, allowing provider to be bit bigger, i.e. have some extra
 padding after the FS image. That in some cases might be a side-effect of
 using CLOOP format which enforces certain block size and trying to compress
 image that is not exactly the number of those blocks in size. The UFS itself
 does not have any issues mounting such padded file systems, so it's what
 GEOM_LABEL should do.

Submitted by:	@mizhka_gmail.com
Differential Revision:	https://reviews.freebsd.org/D6208
---
 sys/geom/label/g_label_ufs.c | 42 +++++++++++++++++++++++++++++-------
 1 file changed, 34 insertions(+), 8 deletions(-)

diff --git a/sys/geom/label/g_label_ufs.c b/sys/geom/label/g_label_ufs.c
index ef012a98ef6f..d866311a7a66 100644
--- a/sys/geom/label/g_label_ufs.c
+++ b/sys/geom/label/g_label_ufs.c
@@ -45,6 +45,15 @@ __FBSDID("$FreeBSD$");
 #define	G_LABEL_UFS_VOLUME	0
 #define	G_LABEL_UFS_ID		1
 
+/*
+ * G_LABEL_UFS_CMP returns true if difference between provider mediasize
+ * and filesystem size is less than G_LABEL_UFS_MAXDIFF sectors
+ */
+#define	G_LABEL_UFS_CMP(prov, fsys, size) 				   \
+	( abs( ((fsys)->size) - ( (prov)->mediasize / (fsys)->fs_fsize ))  \
+				< G_LABEL_UFS_MAXDIFF )
+#define	G_LABEL_UFS_MAXDIFF	0x100
+
 static const int superblocks[] = SBLOCKSEARCH;
 
 static void
@@ -82,18 +91,35 @@ g_label_ufs_taste_common(struct g_consumer *cp, char *label, size_t size, int wh
 		if (fs == NULL)
 			continue;
 		/*
-		 * Check for magic. We also need to check if file system size is equal
-		 * to providers size, because sysinstall(8) used to bogusly put first
-		 * partition at offset 0 instead of 16, and glabel/ufs would find file
-		 * system on slice instead of partition.
+		 * Check for magic. We also need to check if file system size
+		 * is almost equal to providers size, because sysinstall(8)
+		 * used to bogusly put first partition at offset 0
+		 * instead of 16, and glabel/ufs would find file system on slice
+		 * instead of partition.
+		 *
+		 * In addition, media size can be a bit bigger than file system
+		 * size. For instance, mkuzip can append bytes to align data
+		 * to large sector size (it improves compression rates).
 		 */
+		switch (fs->fs_magic){
+		case FS_UFS1_MAGIC:
+		case FS_UFS2_MAGIC:
+			G_LABEL_DEBUG(1, "%s %s params: %jd, %d, %d, %jd\n",
+				fs->fs_magic == FS_UFS1_MAGIC ? "UFS1" : "UFS2",
+				pp->name, pp->mediasize, fs->fs_fsize,
+				fs->fs_old_size, fs->fs_providersize);
+			break;
+		default:
+			break;
+		}
+
 		if (fs->fs_magic == FS_UFS1_MAGIC && fs->fs_fsize > 0 &&
-		    ((pp->mediasize / fs->fs_fsize == fs->fs_old_size) ||
-		    (pp->mediasize / fs->fs_fsize == fs->fs_providersize))) {
+		    ( G_LABEL_UFS_CMP(pp, fs, fs_old_size)
+			|| G_LABEL_UFS_CMP(pp, fs, fs_providersize))) {
 		    	/* Valid UFS1. */
 		} else if (fs->fs_magic == FS_UFS2_MAGIC && fs->fs_fsize > 0 &&
-		    ((pp->mediasize / fs->fs_fsize == fs->fs_size) ||
-		    (pp->mediasize / fs->fs_fsize == fs->fs_providersize))) {
+		    ( G_LABEL_UFS_CMP(pp, fs, fs_size)
+			|| G_LABEL_UFS_CMP(pp, fs, fs_providersize))) {
 		    	/* Valid UFS2. */
 		} else {
 			g_free(fs);