[PATCH] ext3: Add "-o bh" option

This patch adds "-o bh" option to force use of buffer_heads.  This option
is needed when we make "nobh" as default - and if we run into problems.

Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 13 insertions, 1 deletions

diff --git a/Documentation/filesystems/ext3.txt b/Documentation/filesystems/ext3.txt
index afb1335c05d6..4aecc9bdb273 100644
--- a/Documentation/filesystems/ext3.txt
+++ b/Documentation/filesystems/ext3.txt
@@ -113,6 +113,14 @@ noquota
 grpquota
 usrquota
 
+bh              (*)     ext3 associates buffer heads to data pages to
+nobh                    (a) cache disk block mapping information
+                        (b) link pages into transaction to provide
+                            ordering guarantees.
+                        "bh" option forces use of buffer heads.
+                        "nobh" option tries to avoid associating buffer
+                        heads (supported only for "writeback" mode).
+
 
 Specification
 =============
diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index b2891cc29db1..b7483360a2db 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -630,7 +630,7 @@ enum {
         Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic, Opt_err_ro,
         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_reservation, Opt_noreservation, Opt_noload, Opt_nobh, Opt_bh,
         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,
@@ -666,6 +666,7 @@ static match_table_t tokens = {
         {Opt_noreservation, "noreservation"},
         {Opt_noload, "noload"},
         {Opt_nobh, "nobh"},
+        {Opt_bh, "bh"},
         {Opt_commit, "commit=%u"},
         {Opt_journal_update, "journal=update"},
         {Opt_journal_inum, "journal=%u"},
@@ -1014,6 +1015,9 @@ clear_qf_name:
                 case Opt_nobh:
                         set_opt(sbi->s_mount_opt, NOBH);
                         break;
+                case Opt_bh:
+                        clear_opt(sbi->s_mount_opt, NOBH);
+                        break;
                 default:
                         printk (KERN_ERR
                                 "EXT3-fs: Unrecognized mount option \"%s\" "