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Date:      Sun, 25 Nov 2018 18:01:15 +0000 (UTC)
From:      Kirk McKusick <mckusick@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r340924 - head/sys/ufs/ffs
Message-ID:  <201811251801.wAPI1F0f084795@repo.freebsd.org>
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Author: mckusick
Date: Sun Nov 25 18:01:15 2018
New Revision: 340924
URL: https://svnweb.freebsd.org/changeset/base/340924

Log:
  Calculate updated superblock check-hash before writing it into the snapshot.
  This corrects a bug that prevented snapshots from being mounted due to a
  superblock check-hash failure.
  
  Reported by:  Brennan Vincent <brennan@umanwizard.com>
  Tested by:    Peter Holm (pho@)
  Sponsored by: Netflix

Modified:
  head/sys/ufs/ffs/ffs_extern.h
  head/sys/ufs/ffs/ffs_snapshot.c
  head/sys/ufs/ffs/ffs_subr.c

Modified: head/sys/ufs/ffs/ffs_extern.h
==============================================================================
--- head/sys/ufs/ffs/ffs_extern.h	Sun Nov 25 18:00:50 2018	(r340923)
+++ head/sys/ufs/ffs/ffs_extern.h	Sun Nov 25 18:01:15 2018	(r340924)
@@ -68,6 +68,7 @@ ufs2_daddr_t ffs_blkpref_ufs1(struct inode *, ufs_lbn_
 ufs2_daddr_t ffs_blkpref_ufs2(struct inode *, ufs_lbn_t, int, ufs2_daddr_t *);
 void	ffs_blkrelease_finish(struct ufsmount *, u_long);
 u_long	ffs_blkrelease_start(struct ufsmount *, struct vnode *, ino_t);
+uint32_t ffs_calc_sbhash(struct fs *);
 int	ffs_checkfreefile(struct fs *, struct vnode *, ino_t);
 void	ffs_clrblock(struct fs *, u_char *, ufs1_daddr_t);
 void	ffs_clusteracct(struct fs *, struct cg *, ufs1_daddr_t, int);

Modified: head/sys/ufs/ffs/ffs_snapshot.c
==============================================================================
--- head/sys/ufs/ffs/ffs_snapshot.c	Sun Nov 25 18:00:50 2018	(r340923)
+++ head/sys/ufs/ffs/ffs_snapshot.c	Sun Nov 25 18:01:15 2018	(r340924)
@@ -795,6 +795,7 @@ out1:
 		brelse(nbp);
 	} else {
 		loc = blkoff(fs, fs->fs_sblockloc);
+		copy_fs->fs_ckhash = ffs_calc_sbhash(copy_fs);
 		bcopy((char *)copy_fs, &nbp->b_data[loc], (u_int)fs->fs_sbsize);
 		bawrite(nbp);
 	}

Modified: head/sys/ufs/ffs/ffs_subr.c
==============================================================================
--- head/sys/ufs/ffs/ffs_subr.c	Sun Nov 25 18:00:50 2018	(r340923)
+++ head/sys/ufs/ffs/ffs_subr.c	Sun Nov 25 18:01:15 2018	(r340924)
@@ -46,6 +46,7 @@ __FBSDID("$FreeBSD$");
 #include <ufs/ffs/fs.h>
 
 uint32_t calculate_crc32c(uint32_t, const void *, size_t);
+uint32_t ffs_calc_sbhash(struct fs *);
 struct malloc_type;
 #define UFS_MALLOC(size, type, flags) malloc(size)
 #define UFS_FREE(ptr, type) free(ptr)
@@ -147,7 +148,6 @@ ffs_load_inode(struct buf *bp, struct inode *ip, struc
 static off_t sblock_try[] = SBLOCKSEARCH;
 static int readsuper(void *, struct fs **, off_t, int,
 	int (*)(void *, off_t, void **, int));
-static uint32_t calc_sbhash(struct fs *);
 
 /*
  * Read a superblock from the devfd device.
@@ -276,7 +276,7 @@ readsuper(void *devfd, struct fs **fsp, off_t sblocklo
 	    fs->fs_bsize <= MAXBSIZE &&
 	    fs->fs_bsize >= roundup(sizeof(struct fs), DEV_BSIZE) &&
 	    fs->fs_sbsize <= SBLOCKSIZE) {
-		if (fs->fs_ckhash != (ckhash = calc_sbhash(fs))) {
+		if (fs->fs_ckhash != (ckhash = ffs_calc_sbhash(fs))) {
 #ifdef _KERNEL
 			res = uprintf("Superblock check-hash failed: recorded "
 			    "check-hash 0x%x != computed check-hash 0x%x\n",
@@ -339,7 +339,7 @@ ffs_sbput(void *devfd, struct fs *fs, off_t loc,
 	}
 	fs->fs_fmod = 0;
 	fs->fs_time = UFS_TIME;
-	fs->fs_ckhash = calc_sbhash(fs);
+	fs->fs_ckhash = ffs_calc_sbhash(fs);
 	if ((error = (*writefunc)(devfd, loc, fs, fs->fs_sbsize)) != 0)
 		return (error);
 	return (0);
@@ -348,8 +348,8 @@ ffs_sbput(void *devfd, struct fs *fs, off_t loc,
 /*
  * Calculate the check-hash for a superblock.
  */
-static uint32_t
-calc_sbhash(struct fs *fs)
+uint32_t
+ffs_calc_sbhash(struct fs *fs)
 {
 	uint32_t ckhash, save_ckhash;

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