Re: Reiserfs: how to mount without journal replay?

[Chris Mason <mason@suse.com>]

On Thursday, August 30, 2001 11:50:05 PM +0200 Pavel Machek <pavel@suse.cz> wrote:

> ext2 is willing to mount ro even with known inconsistencies. SuSE 7.1
> does not come with 'live filesystem' and install cd does not have
> reiserfsck on it. Too bad. You have to install somewhere to be able to
> run reiserfsck on suse7.1.

If your reiserfs isn't consistent, your chances of finding reiserfsck in 
the broken btree are slim to none.  A readonly mount in this case is 
unlikely to find a valid, fully intact reiserfsck executable.

The best reason I've heard for a -o noreplay option is for shared 
readonly mounts.  The patch below adds that, with a few conditions:

mount -o noreplay /dev/xxx /mnt

If no log replay is required, rw mount succeeds (ro is -o noreplay,ro is used).

Otherwise, no replay is done, mount is changed to readonly.  Later 
attempts at mount -o rw,remount /mnt will fail with -EIO.

This is lightly tested, and not intended for inclusion anywhere.  If 
there's enough interest, I'll verify and send in.

(against 2.4.10pre4)

-chris

#
--- linux/include/linux/reiserfs_fs_sb.h	Tue Sep  4 14:37:27 2001
+++ linux/include/linux/reiserfs_fs_sb.h	Tue Sep  4 14:39:44 2001
@@ -387,6 +387,7 @@
 #define REISERFS_NO_UNHASHED_RELOCATION 12
 #define REISERFS_HASHED_RELOCATION 13
 #define REISERFS_TEST4 14 
+#define REISERFS_NO_REPLAY 15 
 
 #define REISERFS_TEST1 11
 #define REISERFS_TEST2 12
@@ -401,6 +402,7 @@
 #define reiserfs_no_unhashed_relocation(s) ((s)->u.reiserfs_sb.s_mount_opt & (1 << REISERFS_NO_UNHASHED_RELOCATION))
 #define reiserfs_hashed_relocation(s) ((s)->u.reiserfs_sb.s_mount_opt & (1 << REISERFS_HASHED_RELOCATION))
 #define reiserfs_test4(s) ((s)->u.reiserfs_sb.s_mount_opt & (1 << REISERFS_TEST4))
+#define reiserfs_noreplay(s) ((s)->u.reiserfs_sb.s_mount_opt & (1 << REISERFS_NO_REPLAY))
 
 #define dont_have_tails(s) ((s)->u.reiserfs_sb.s_mount_opt & (1 << NOTAIL))
 #define replay_only(s) ((s)->u.reiserfs_sb.s_mount_opt & (1 << REPLAYONLY))
--- linux/include/linux/reiserfs_fs.h	Tue Sep  4 14:37:27 2001
+++ linux/include/linux/reiserfs_fs.h	Tue Sep  4 15:47:43 2001
@@ -1723,6 +1723,7 @@
 */
 #define JOURNAL_BUFFER(j,n) ((j)->j_ap_blocks[((j)->j_start + (n)) % JOURNAL_BLOCK_COUNT])
 
+int reiserfs_replay_error(struct super_block *s) ;
 void reiserfs_wait_on_write_block(struct super_block *s) ;
 void reiserfs_block_writes(struct reiserfs_transaction_handle *th) ;
 void reiserfs_allow_writes(struct super_block *s) ;
--- linux/fs/reiserfs/journal.c	Sun Sep  2 03:52:37 2001
+++ linux/fs/reiserfs/journal.c	Tue Sep  4 15:57:59 2001
@@ -96,6 +96,7 @@
 
 /* state bits for the journal */
 #define WRITERS_BLOCKED 1      /* set when new writers not allowed */
+#define REPLAY_ERROR 2      /* set when -o noreplay forces unclean mount */
 
 static int do_journal_end(struct reiserfs_transaction_handle *,struct super_block *,unsigned long nblocks,int flags) ;
 static int flush_journal_list(struct super_block *s, struct reiserfs_journal_list *jl, int flushall) ;
@@ -106,6 +107,10 @@
   memset(SB_JOURNAL(p_s_sb)->j_hash_table, 0, JOURNAL_HASH_SIZE * sizeof(struct reiserfs_journal_cnode *)) ;
 }
 
+int reiserfs_replay_error(struct super_block *s) {
+    return test_bit(REPLAY_ERROR, &SB_JOURNAL(s)->j_state) ;
+}
+
 /*
 ** clears BH_Dirty and sticks the buffer on the clean list.  Called because I can't allow refile_buffer to
 ** make schedule happen after I've freed a block.  Look at remove_from_transaction and journal_mark_freed for
@@ -1651,12 +1656,20 @@
     brelse(d_bh) ;
   }
 
-  if (continue_replay && is_read_only(p_s_sb->s_dev)) {
-    printk("clm-2076: device is readonly, unable to replay log\n") ;
-    return -1 ;
-  }
-  if (continue_replay && (p_s_sb->s_flags & MS_RDONLY)) {
-    printk("Warning, log replay starting on readonly filesystem\n") ;    
+  if (continue_replay) {
+    if (is_read_only(p_s_sb->s_dev)) {
+      printk("clm-2076: device is readonly, unable to replay log\n") ;
+      return -1 ;
+    }
+    if (reiserfs_noreplay(p_s_sb)) {
+      printk("-o noreplay used to force unclean mount.  FS set to readonly\n");
+      p_s_sb->s_flags |= MS_RDONLY ;
+      set_bit(REPLAY_ERROR, &SB_JOURNAL(p_s_sb)->j_state) ;
+      return 0 ;
+    }
+    if (p_s_sb->s_flags & MS_RDONLY) {
+      printk("Warning, log replay starting on readonly filesystem\n") ;    
+    }
   }
 
   /* ok, there are transactions that need to be replayed.  start with the first log block, find
@@ -2022,6 +2035,12 @@
     th->t_super = p_s_sb ; /* others will check this for the don't log flag */
     return 0 ;
   }
+
+  if (test_bit(REPLAY_ERROR, &SB_JOURNAL(p_s_sb)->j_state)) {
+    printk("clm-2100: calling journal_begin after replay errors\n") ;
+    BUG() ;
+  }
+  
 
 relock:
   lock_journal(p_s_sb) ;
--- linux/fs/reiserfs/super.c	Tue Sep  4 14:37:28 2001
+++ linux/fs/reiserfs/super.c	Tue Sep  4 15:58:02 2001
@@ -176,6 +176,8 @@
 	    set_bit (REISERFS_HASHED_RELOCATION, mount_options);
 	} else if (!strcmp (this_char, "test4")) {
 	    set_bit (REISERFS_TEST4, mount_options);
+	} else if (!strcmp (this_char, "noreplay")) {
+	    set_bit (REISERFS_NO_REPLAY, mount_options);
 	} else if (!strcmp (this_char, "nolog")) {
 	    reiserfs_warning("reiserfs: nolog mount option not supported yet\n");
 	} else if (!strcmp (this_char, "replayonly")) {
@@ -268,6 +270,14 @@
     journal_mark_dirty(&th, s, SB_BUFFER_WITH_SB (s));
     s->s_dirt = 0;
   } else {
+    /* if we are currently readonly, and were mounted with noreplay, 
+    ** we need to check if replay failed and the journal params are not
+    ** correctly set.  If so, we cannot allow a rw mount, horrible, horrible
+    ** things would happen
+    */
+    if (reiserfs_replay_error(s)) {
+      return -EIO ;
+    }
     s->u.reiserfs_sb.s_mount_state = sb_state(rs) ;
     s->s_flags &= ~MS_RDONLY ; /* now it is safe to call journal_begin */
     journal_begin(&th, s, 10) ;