Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6
* '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
--- a/fs/ext3/Kconfig
+++ b/fs/ext3/Kconfig
@@ -29,23 +29,25 @@
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'.
+ 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:
- 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.
+ http://ext4.wiki.kernel.org/index.php/Ext3_data_mode_tradeoffs
- 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.
+ 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
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -543,6 +543,19 @@
#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 @@
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 @@
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;