[PATCH] ext3: external journal device as a mount option

The patch below adds a new mount option to allow the external journal
device to be specified.

The syntax is as follows:
# mount -t ext3 -o journal_dev=0x0820 ...
where 0x0820 means major=8 and minor=32.

Signed-off-by: Johann Lombardi <johann.lombardi@bull.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 44 insertions, 10 deletions

diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index 4e6730622d90..7c45acf94589 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -43,7 +43,8 @@
 #include "acl.h"
 #include "namei.h"
 
-static int ext3_load_journal(struct super_block *, struct ext3_super_block *);
+static int ext3_load_journal(struct super_block *, struct ext3_super_block *,
+                             unsigned long journal_devnum);
 static int ext3_create_journal(struct super_block *, struct ext3_super_block *,
                                int);
 static void ext3_commit_super (struct super_block * sb,
@@ -628,7 +629,7 @@ enum {
         Opt_nouid32, Opt_nocheck, Opt_debug, Opt_oldalloc, Opt_orlov,
         Opt_user_xattr, Opt_nouser_xattr, Opt_acl, Opt_noacl,
         Opt_reservation, Opt_noreservation, Opt_noload, Opt_nobh,
-        Opt_commit, Opt_journal_update, Opt_journal_inum,
+        Opt_commit, Opt_journal_update, Opt_journal_inum, Opt_journal_dev,
         Opt_abort, Opt_data_journal, Opt_data_ordered, Opt_data_writeback,
         Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,
         Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_quota, Opt_noquota,
@@ -666,6 +667,7 @@ static match_table_t tokens = {
         {Opt_commit, "commit=%u"},
         {Opt_journal_update, "journal=update"},
         {Opt_journal_inum, "journal=%u"},
+        {Opt_journal_dev, "journal_dev=%u"},
         {Opt_abort, "abort"},
         {Opt_data_journal, "data=journal"},
         {Opt_data_ordered, "data=ordered"},
@@ -705,8 +707,9 @@ static unsigned long get_sb_block(void **data)
         return sb_block;
 }
 
-static int parse_options (char * options, struct super_block *sb,
-                          unsigned long * inum, unsigned long *n_blocks_count, int is_remount)
+static int parse_options (char *options, struct super_block *sb,
+                          unsigned long *inum, unsigned long *journal_devnum,
+                          unsigned long *n_blocks_count, int is_remount)
 {
         struct ext3_sb_info *sbi = EXT3_SB(sb);
         char * p;
@@ -839,6 +842,16 @@ static int parse_options (char * options, struct super_block *sb,
                                 return 0;
                         *inum = option;
                         break;
+                case Opt_journal_dev:
+                        if (is_remount) {
+                                printk(KERN_ERR "EXT3-fs: cannot specify "
+                                       "journal on remount\n");
+                                return 0;
+                        }
+                        if (match_int(&args[0], &option))
+                                return 0;
+                        *journal_devnum = option;
+                        break;
                 case Opt_noload:
                         set_opt (sbi->s_mount_opt, NOLOAD);
                         break;
@@ -1331,6 +1344,7 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
         unsigned long logic_sb_block;
         unsigned long offset = 0;
         unsigned long journal_inum = 0;
+        unsigned long journal_devnum = 0;
         unsigned long def_mount_opts;
         struct inode *root;
         int blocksize;
@@ -1411,7 +1425,8 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
 
         set_opt(sbi->s_mount_opt, RESERVATION);
 
-        if (!parse_options ((char *) data, sb, &journal_inum, NULL, 0))
+        if (!parse_options ((char *) data, sb, &journal_inum, &journal_devnum,
+                            NULL, 0))
                 goto failed_mount;
 
         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
@@ -1622,7 +1637,7 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
          */
         if (!test_opt(sb, NOLOAD) &&
             EXT3_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL)) {
-                if (ext3_load_journal(sb, es))
+                if (ext3_load_journal(sb, es, journal_devnum))
                         goto failed_mount2;
         } else if (journal_inum) {
                 if (ext3_create_journal(sb, es, journal_inum))
@@ -1902,15 +1917,24 @@ out_bdev:
         return NULL;
 }
 
-static int ext3_load_journal(struct super_block * sb,
-                             struct ext3_super_block * es)
+static int ext3_load_journal(struct super_block *sb,
+                             struct ext3_super_block *es,
+                             unsigned long journal_devnum)
 {
         journal_t *journal;
         int journal_inum = le32_to_cpu(es->s_journal_inum);
-        dev_t journal_dev = new_decode_dev(le32_to_cpu(es->s_journal_dev));
+        dev_t journal_dev;
         int err = 0;
         int really_read_only;
 
+        if (journal_devnum &&
+            journal_devnum != le32_to_cpu(es->s_journal_dev)) {
+                printk(KERN_INFO "EXT3-fs: external journal device major/minor "
+                        "numbers have changed\n");
+                journal_dev = new_decode_dev(journal_devnum);
+        } else
+                journal_dev = new_decode_dev(le32_to_cpu(es->s_journal_dev));
+
         really_read_only = bdev_read_only(sb->s_bdev);
 
         /*
@@ -1969,6 +1993,16 @@ static int ext3_load_journal(struct super_block * sb,
 
         EXT3_SB(sb)->s_journal = journal;
         ext3_clear_journal_err(sb, es);
+
+        if (journal_devnum &&
+            journal_devnum != le32_to_cpu(es->s_journal_dev)) {
+                es->s_journal_dev = cpu_to_le32(journal_devnum);
+                sb->s_dirt = 1;
+
+                /* Make sure we flush the recovery flag to disk. */
+                ext3_commit_super(sb, es, 1);
+        }
+
         return 0;
 }
 
@@ -2197,7 +2231,7 @@ static int ext3_remount (struct super_block * sb, int * flags, char * data)
         /*
          * Allow the "check" option to be passed as a remount option.
          */
-        if (!parse_options(data, sb, NULL, &n_blocks_count, 1)) {
+        if (!parse_options(data, sb, NULL, NULL, &n_blocks_count, 1)) {
                 err = -EINVAL;
                 goto restore_opts;
         }