Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux...

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6:
  ext3: Improve error message that changing journaling mode on remount is not possible
  ext3: Update Kconfig description of EXT3_DEFAULTS_TO_ORDERED

diff --git a/fs/ext3/Kconfig b/fs/ext3/Kconfig
index fb3c1a2..522b154 100644 (file)
--- a/fs/ext3/Kconfig
+++ b/fs/ext3/Kconfig
@@ -29,23 +29,25 @@ config EXT3_FS
          module will be called ext3.
 
 config EXT3_DEFAULTS_TO_ORDERED
-       bool "Default to 'data=ordered' in ext3 (legacy option)"
+       bool "Default to 'data=ordered' in ext3"
        depends on EXT3_FS
        help
-         If a filesystem does not explicitly specify a data ordering
-         mode, and the journal capability allowed it, ext3 used to
-         historically default to 'data=ordered'.
-
-         That was a rather unfortunate choice, because it leads to all
-         kinds of latency problems, and the 'data=writeback' mode is more
-         appropriate these days.
-
-         You should probably always answer 'n' here, and if you really
-         want to use 'data=ordered' mode, set it in the filesystem itself
-         with 'tune2fs -o journal_data_ordered'.
-
-         But if you really want to enable the legacy default, you can do
-         so by answering 'y' to this question.
+         The journal mode options for ext3 have different tradeoffs
+         between when data is guaranteed to be on disk and
+         performance.  The use of "data=writeback" can cause
+         unwritten data to appear in files after an system crash or
+         power failure, which can be a security issue.  However,
+         "data=ordered" mode can also result in major performance
+         problems, including seconds-long delays before an fsync()
+         call returns.  For details, see:
+
+         http://ext4.wiki.kernel.org/index.php/Ext3_data_mode_tradeoffs
+
+         If you have been historically happy with ext3's performance,
+         data=ordered mode will be a safe choice and you should
+         answer 'y' here.  If you understand the reliability and data
+         privacy issues of data=writeback and are willing to make
+         that trade off, answer 'n'.
 
 config EXT3_FS_XATTR
        bool "Ext3 extended attributes"

diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index 524b349..a8d80a7 100644 (file)
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -543,6 +543,19 @@ static inline void ext3_show_quota_options(struct seq_file *seq, struct super_bl
 #endif
 }
 
+static char *data_mode_string(unsigned long mode)
+{
+       switch (mode) {
+       case EXT3_MOUNT_JOURNAL_DATA:
+               return "journal";
+       case EXT3_MOUNT_ORDERED_DATA:
+               return "ordered";
+       case EXT3_MOUNT_WRITEBACK_DATA:
+               return "writeback";
+       }
+       return "unknown";
+}
+
 /*
  * Show an option if
  *  - it's set to a non-default value OR
@@ -616,13 +629,8 @@ static int ext3_show_options(struct seq_file *seq, struct vfsmount *vfs)
        if (test_opt(sb, NOBH))
                seq_puts(seq, ",nobh");
 
-       if (test_opt(sb, DATA_FLAGS) == EXT3_MOUNT_JOURNAL_DATA)
-               seq_puts(seq, ",data=journal");
-       else if (test_opt(sb, DATA_FLAGS) == EXT3_MOUNT_ORDERED_DATA)
-               seq_puts(seq, ",data=ordered");
-       else if (test_opt(sb, DATA_FLAGS) == EXT3_MOUNT_WRITEBACK_DATA)
-               seq_puts(seq, ",data=writeback");
-
+       seq_printf(seq, ",data=%s", data_mode_string(sbi->s_mount_opt &
+                                                    EXT3_MOUNT_DATA_FLAGS));
        if (test_opt(sb, DATA_ERR_ABORT))
                seq_puts(seq, ",data_err=abort");
 
@@ -1024,12 +1032,18 @@ static int parse_options (char *options, struct super_block *sb,
                datacheck:
                        if (is_remount) {
                                if ((sbi->s_mount_opt & EXT3_MOUNT_DATA_FLAGS)
-                                               != data_opt) {
-                                       printk(KERN_ERR
-                                               "EXT3-fs: cannot change data "
-                                               "mode on remount\n");
-                                       return 0;
-                               }
+                                               == data_opt)
+                                       break;
+                               printk(KERN_ERR
+                                       "EXT3-fs (device %s): Cannot change "
+                                       "data mode on remount. The filesystem "
+                                       "is mounted in data=%s mode and you "
+                                       "try to remount it in data=%s mode.\n",
+                                       sb->s_id,
+                                       data_mode_string(sbi->s_mount_opt &
+                                                       EXT3_MOUNT_DATA_FLAGS),
+                                       data_mode_string(data_opt));
+                               return 0;
                        } else {
                                sbi->s_mount_opt &= ~EXT3_MOUNT_DATA_FLAGS;
                                sbi->s_mount_opt |= data_opt;