svn commit: r302985 - head/sys/geom/label

[Maxim Sobolev]

Author: sobomax
Date: Mon Jul 18 05:00:01 2016
New Revision: 302985
URL: https://svnweb.freebsd.org/changeset/base/302985

Log:
  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

Modified:
  head/sys/geom/label/g_label_ufs.c

Modified: head/sys/geom/label/g_label_ufs.c
==============================================================================
--- head/sys/geom/label/g_label_ufs.c	Mon Jul 18 04:36:18 2016	(r302984)
+++ head/sys/geom/label/g_label_ufs.c	Mon Jul 18 05:00:01 2016	(r302985)
@@ -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_consum
 		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);