[PATCH] Add "commit=0" to reiserfs

From: Bart Samwel <bart@samwel.tk>

Add support for value 0 to the commit option of reiserfs.  Means "restore
to the default value".  For the maximum commit age, this default value is
normally read from the journal; this patch adds an extra variable to cache
the default value for the maximum commit age.

fs/reiserfs/journal.c

@@ -2308,6 +2308,7 @@ int journal_init(struct super_block *p_s_sb, const char * j_dev_name, int old_fo
       SB_JOURNAL_MAX_TRANS_AGE(p_s_sb) = commit_max_age;
   } else {
       SB_JOURNAL_MAX_COMMIT_AGE(p_s_sb) = le32_to_cpu (jh->jh_journal.jp_journal_max_commit_age);
+      SB_JOURNAL_DEFAULT_MAX_COMMIT_AGE(p_s_sb) = SB_JOURNAL_MAX_COMMIT_AGE(p_s_sb);
       SB_JOURNAL_MAX_TRANS_AGE(p_s_sb)  = JOURNAL_MAX_TRANS_AGE;
   }
 

fs/reiserfs/super.c

@@ -709,13 +709,11 @@ static int reiserfs_parse_options (struct super_block * s, char * options, /* st
 		char *p = 0;
 		int val = simple_strtoul (arg, &p, 0);
 		/* commit=NNN (time in seconds) */
-		if ( *p != '\0' || val == 0) {
+		if ( *p != '\0' || val < 0) {
 			printk ("reiserfs_parse_options: bad value %s\n", arg);
 			return 0;
 		}
-		if ( val > 0 ) {
-			*commit_max_age = val;
-		}
+		*commit_max_age = val;
 	}
 
 	if ( c == 'w' ) {
@@ -821,8 +819,14 @@ static int reiserfs_remount (struct super_block * s, int * mount_flags, char * a
   REISERFS_SB(s)->s_mount_opt = (REISERFS_SB(s)->s_mount_opt & ~safe_mask) |  (mount_options & safe_mask);
 
   if(commit_max_age != 0) {
-	  SB_JOURNAL_MAX_COMMIT_AGE(s) = commit_max_age;
-	  SB_JOURNAL_MAX_TRANS_AGE(s) = commit_max_age;
+    SB_JOURNAL_MAX_COMMIT_AGE(s) = commit_max_age;
+    SB_JOURNAL_MAX_TRANS_AGE(s) = commit_max_age;
+  }
+  else
+  {
+    /* 0 means restore defaults. */
+    SB_JOURNAL_MAX_COMMIT_AGE(s) = SB_JOURNAL_DEFAULT_MAX_COMMIT_AGE(s);
+    SB_JOURNAL_MAX_TRANS_AGE(s) = JOURNAL_MAX_TRANS_AGE;
   }
 
   if(blocks) {

include/linux/reiserfs_fs_sb.h

@@ -208,6 +208,7 @@ struct reiserfs_journal {
   unsigned int s_journal_trans_max ;           /* max number of blocks in a transaction.  */
   unsigned int s_journal_max_batch ;           /* max number of blocks to batch into a trans */
   unsigned int s_journal_max_commit_age ;      /* in seconds, how old can an async commit be */
+  unsigned int s_journal_default_max_commit_age ; /* the default for the max commit age */
   unsigned int s_journal_max_trans_age ;       /* in seconds, how old can a transaction be */  
 
   struct reiserfs_journal_cnode *j_cnode_free_list ;
@@ -481,6 +482,7 @@ int reiserfs_resize(struct super_block *, unsigned long) ;
 #define SB_JOURNAL_TRANS_MAX(s)      (SB_JOURNAL(s)->s_journal_trans_max)
 #define SB_JOURNAL_MAX_BATCH(s)      (SB_JOURNAL(s)->s_journal_max_batch)
 #define SB_JOURNAL_MAX_COMMIT_AGE(s) (SB_JOURNAL(s)->s_journal_max_commit_age)
+#define SB_JOURNAL_DEFAULT_MAX_COMMIT_AGE(s) (SB_JOURNAL(s)->s_journal_default_max_commit_age)
 #define SB_JOURNAL_MAX_TRANS_AGE(s)  (SB_JOURNAL(s)->s_journal_max_trans_age)
 
 /* A safe version of the "bdevname", which returns the "s_id" field of