diff options
| author | Eric Sandeen <sandeen@redhat.com> | 2008-05-26 20:29:46 +0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2008-05-26 20:29:46 +0400 |
| commit | 571640cad3fda6475da45d91cf86076f1f86bd9b (patch) | |
| tree | a97ff3da9b60251c68358cd000c217cb37915ea2 | |
| parent | 034772b068be62a79470d6c1b81b01fbe27793ac (diff) | |
| download | linux-571640cad3fda6475da45d91cf86076f1f86bd9b.tar.xz | |
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>
| -rw-r--r-- | Documentation/filesystems/ext4.txt | 12 | ||||
| -rw-r--r-- | fs/ext4/super.c | 11 |
2 files changed, 19 insertions, 4 deletions
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt index 560f88dc7090..0c5086db8352 100644 --- a/Documentation/filesystems/ext4.txt +++ b/Documentation/filesystems/ext4.txt @@ -139,8 +139,16 @@ commit=nrsec (*) Ext4 can be told to sync all its data and metadata Setting it to very large values will improve performance. -barrier=1 This enables/disables barriers. barrier=0 disables - it, barrier=1 enables it. +barrier=<0|1(*)> This enables/disables the use of write barriers in + the jbd code. barrier=0 disables, barrier=1 enables. + This also requires an IO stack which can support + barriers, and if jbd gets an error on a barrier + write, it will disable again with a warning. + Write barriers enforce proper on-disk ordering + of journal commits, making volatile disk write caches + safe to use, at some performance penalty. If + your disks are battery-backed in one way or another, + disabling barriers may safely improve performance. orlov (*) This enables the new Orlov block allocator. It is enabled by default. diff --git a/fs/ext4/super.c b/fs/ext4/super.c index ba92c606ad9a..cb96f127c366 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -671,6 +671,7 @@ static int ext4_show_options(struct seq_file *seq, struct vfsmount *vfs) 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 @@ static int ext4_show_options(struct seq_file *seq, struct vfsmount *vfs) 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 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent) 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 |