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Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6

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* '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
This commit is contained in:
Linus Torvalds 2009-08-25 09:47:36 -07:00
commit e9cab24cf3
2 changed files with 42 additions and 26 deletions
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28
fs/ext3/Kconfig
View file

@ -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'.
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"

36
fs/ext3/super.c
View file

@ -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) {
== data_opt)
break;
printk(KERN_ERR
"EXT3-fs: cannot change data "
"mode on remount\n");
"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;