2010-07-07 11:12:45 +00:00
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From: Chris Mason <mason@suse.com>
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Subject: make ext3 mount default to barrier=1
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Patch-mainline: probably never
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Hello everyone,
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This patch turns on barriers by default for ext3. mount -o barrier=0
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will turn them off. It also changes the ext3 fsync call to trigger a
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barrier when a commit isn't done.
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It should be safe, but some extra review would be appreciated.
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Updated Apr 13 2009 jeffm:
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- Added Kconfig option
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Acked-by: Jeff Mahoney <jeffm@suse.com>
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---
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fs/ext3/Kconfig | 22 ++++++++++++++++++++++
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fs/ext3/fsync.c | 1 +
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fs/ext3/super.c | 4 ++++
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3 files changed, 27 insertions(+)
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--- a/fs/ext3/Kconfig
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+++ b/fs/ext3/Kconfig
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2011-04-19 20:09:59 +00:00
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@@ -50,6 +50,28 @@ config EXT3_DEFAULTS_TO_ORDERED
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2010-07-07 11:12:45 +00:00
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privacy issues of data=writeback and are willing to make
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that trade off, answer 'n'.
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+config EXT3_DEFAULTS_TO_BARRIERS_ENABLED
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+ bool "Default to 'barrier=1' in ext3"
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+ depends on EXT3_FS
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+ help
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+ Modern disk drives support write caches that can speed up writeback.
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+ Some devices, in order to improve their performance statistics,
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+ report that the write has been completed even when it has only
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+ been committed to volatile cache memory. This can result in
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+ severe corruption in the event of power loss.
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+
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+ The -o barrier option enables the file system to direct the block
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+ layer to issue a barrier, which ensures that the cache has been
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+ flushed before proceeding. This can produce some slowdown in
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+ certain environments, but allows higher end storage arrays with
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+ battery-backed caches to report completes writes sooner than
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+ would be otherwise possible.
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+
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+ Without this option, disk write caches should be disabled if
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+ you value data integrity over writeback performance.
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+
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+ If unsure, say N.
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+
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config EXT3_FS_XATTR
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bool "Ext3 extended attributes"
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depends on EXT3_FS
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--- a/fs/ext3/fsync.c
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+++ b/fs/ext3/fsync.c
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@@ -28,6 +28,7 @@
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#include <linux/sched.h>
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#include <linux/writeback.h>
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#include <linux/jbd.h>
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+#include <linux/blkdev.h>
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#include <linux/ext3_fs.h>
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#include <linux/ext3_jbd.h>
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--- a/fs/ext3/super.c
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+++ b/fs/ext3/super.c
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2011-04-19 20:09:59 +00:00
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@@ -1693,6 +1693,10 @@ static int ext3_fill_super (struct super
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2010-07-07 11:12:45 +00:00
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sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
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sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
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+ /* enable barriers by default */
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+#ifdef CONFIG_EXT3_DEFAULTS_TO_BARRIERS_ENABLED
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+ set_opt(sbi->s_mount_opt, BARRIER);
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+#endif
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set_opt(sbi->s_mount_opt, RESERVATION);
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if (!parse_options ((char *) data, sb, &journal_inum, &journal_devnum,
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