ext4: enable barriers by default
I can't think of any valid reason for ext4 to not use barriers when
they are available; I believe this is necessary for filesystem
integrity in the face of a volatile write cache on storage.
An administrator who trusts that the cache is sufficiently battery-
backed (and power supplies are sufficiently redundant, etc...)
can always turn it back off again.
SuSE has carried such a patch for ext3 for quite some time now.
Also document the mount option while we're at it.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index ba92c60..cb96f127c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -671,6 +671,7 @@
unsigned long def_mount_opts;
struct super_block *sb = vfs->mnt_sb;
struct ext4_sb_info *sbi = EXT4_SB(sb);
+ journal_t *journal = sbi->s_journal;
struct ext4_super_block *es = sbi->s_es;
def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
@@ -729,8 +730,13 @@
seq_printf(seq, ",commit=%u",
(unsigned) (sbi->s_commit_interval / HZ));
}
- if (test_opt(sb, BARRIER))
- seq_puts(seq, ",barrier=1");
+ /*
+ * We're changing the default of barrier mount option, so
+ * let's always display its mount state so it's clear what its
+ * status is.
+ */
+ seq_puts(seq, ",barrier=");
+ seq_puts(seq, test_opt(sb, BARRIER) ? "1" : "0");
if (test_opt(sb, JOURNAL_ASYNC_COMMIT))
seq_puts(seq, ",journal_async_commit");
if (test_opt(sb, NOBH))
@@ -1909,6 +1915,7 @@
sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
set_opt(sbi->s_mount_opt, RESERVATION);
+ set_opt(sbi->s_mount_opt, BARRIER);
/*
* turn on extents feature by default in ext4 filesystem