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authorTheodore Ts'o <tytso@mit.edu>2009-08-10 16:03:43 -0400
committerJan Kara <jack@suse.cz>2009-08-24 10:48:32 -0400
commit6d41807614151829ae17a3a58bff8572af5e407e (patch)
tree8d507b9ed679e2a42f9e1c8f4e7ba5a958360ea2 /fs
parentf4b9a988685da6386d7f9a72df3098bcc3270526 (diff)
ext3: Update Kconfig description of EXT3_DEFAULTS_TO_ORDERED
The old description for this configuration option was perhaps not completely balanced in terms of describing the tradeoffs of using a default of data=writeback vs. data=ordered. Despite the fact that old description very strongly recomended disabling this feature, all of the major distributions have elected to preserve the existing 'legacy' default, which is a strong hint that it perhaps wasn't telling the whole story. This revised description has been vetted by a number of ext3 developers as being better at informing the user about the tradeoffs of enabling or disabling this configuration feature. Cc: linux-ext4@vger.kernel.org Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs')
-rw-r--r--fs/ext3/Kconfig32
1 files changed, 17 insertions, 15 deletions
diff --git a/fs/ext3/Kconfig b/fs/ext3/Kconfig
index fb3c1a21b135..522b15498f45 100644
--- a/fs/ext3/Kconfig
+++ b/fs/ext3/Kconfig
@@ -29,23 +29,25 @@ config EXT3_FS
29 module will be called ext3. 29 module will be called ext3.
30 30
31config EXT3_DEFAULTS_TO_ORDERED 31config EXT3_DEFAULTS_TO_ORDERED
32 bool "Default to 'data=ordered' in ext3 (legacy option)" 32 bool "Default to 'data=ordered' in ext3"
33 depends on EXT3_FS 33 depends on EXT3_FS
34 help 34 help
35 If a filesystem does not explicitly specify a data ordering 35 The journal mode options for ext3 have different tradeoffs
36 mode, and the journal capability allowed it, ext3 used to 36 between when data is guaranteed to be on disk and
37 historically default to 'data=ordered'. 37 performance. The use of "data=writeback" can cause
38 38 unwritten data to appear in files after an system crash or
39 That was a rather unfortunate choice, because it leads to all 39 power failure, which can be a security issue. However,
40 kinds of latency problems, and the 'data=writeback' mode is more 40 "data=ordered" mode can also result in major performance
41 appropriate these days. 41 problems, including seconds-long delays before an fsync()
42 42 call returns. For details, see:
43 You should probably always answer 'n' here, and if you really 43
44 want to use 'data=ordered' mode, set it in the filesystem itself 44 http://ext4.wiki.kernel.org/index.php/Ext3_data_mode_tradeoffs
45 with 'tune2fs -o journal_data_ordered'. 45
46 46 If you have been historically happy with ext3's performance,
47 But if you really want to enable the legacy default, you can do 47 data=ordered mode will be a safe choice and you should
48 so by answering 'y' to this question. 48 answer 'y' here. If you understand the reliability and data
49 privacy issues of data=writeback and are willing to make
50 that trade off, answer 'n'.
49 51
50config EXT3_FS_XATTR 52config EXT3_FS_XATTR
51 bool "Ext3 extended attributes" 53 bool "Ext3 extended attributes"