ext4: Regularize mount options

Add support for using the mount options "barrier" and "nobarrier", and
"auto_da_alloc" and "noauto_da_alloc", which is more consistent than
"barrier=<0|1>" or "auto_da_alloc=<0|1>".  Most other ext3/ext4 mount
options use the foo/nofoo naming convention.  We allow the old forms
of these mount options for backwards compatibility.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 5c484aec2bab7110d105af2b4388cdaa83a6882f..97882df0486567c229bb0ee867752da15b24089f 100644 (file)
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -183,8 +183,8 @@ commit=nrsec        (*)     Ext4 can be told to sync all its data and metadata
                        performance.
 
 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
+barrier(*)             the jbd code.  barrier=0 disables, barrier=1 enables.
+nobarrier              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
@@ -192,6 +192,9 @@ barrier=<0|1(*)>    This enables/disables the use of write barriers in
                        safe to use, at some performance penalty.  If
                        your disks are battery-backed in one way or another,
                        disabling barriers may safely improve performance.
+                       The mount options "barrier" and "nobarrier" can
+                       also be used to enable or disable barriers, for
+                       consistency with other ext4 mount options.
 
 inode_readahead=n      This tuning parameter controls the maximum
                        number of inode table blocks that ext4's inode
@@ -313,6 +316,24 @@ journal_ioprio=prio        The I/O priority (from 0 to 7, where 0 is the
                        a slightly higher priority than the default I/O
                        priority.
 
+auto_da_alloc(*)       Many broken applications don't use fsync() when 
+noauto_da_alloc                replacing existing files via patterns such as
+                       fd = open("foo.new")/write(fd,..)/close(fd)/
+                       rename("foo.new", "foo"), or worse yet,
+                       fd = open("foo", O_TRUNC)/write(fd,..)/close(fd).
+                       If auto_da_alloc is enabled, ext4 will detect
+                       the replace-via-rename and replace-via-truncate
+                       patterns and force that any delayed allocation
+                       blocks are allocated such that at the next
+                       journal commit, in the default data=ordered
+                       mode, the data blocks of the new file are forced
+                       to disk before the rename() operation is
+                       commited.  This provides roughly the same level
+                       of guarantees as ext3, and avoids the
+                       "zero-length" problem that can happen when a
+                       system crashes before the delayed allocation
+                       blocks are forced to disk.
+
 Data Mode
 =========
 There are 3 different data modes:

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 45d07cf9df347536c1e109943b7cc816e1465c49..9987bba99db3cc62c2faa887b95783676f83b480 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -867,7 +867,7 @@ static int ext4_show_options(struct seq_file *seq, struct vfsmount *vfs)
                seq_puts(seq, ",data_err=abort");
 
        if (test_opt(sb, NO_AUTO_DA_ALLOC))
-               seq_puts(seq, ",auto_da_alloc=0");
+               seq_puts(seq, ",noauto_da_alloc");
 
        ext4_show_quota_options(seq, sb);
        return 0;
@@ -1018,7 +1018,7 @@ enum {
        Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic, Opt_err_ro,
        Opt_nouid32, Opt_debug, Opt_oldalloc, Opt_orlov,
        Opt_user_xattr, Opt_nouser_xattr, Opt_acl, Opt_noacl,
-       Opt_auto_da_alloc, Opt_noload, Opt_nobh, Opt_bh,
+       Opt_auto_da_alloc, Opt_noauto_da_alloc, Opt_noload, Opt_nobh, Opt_bh,
        Opt_commit, Opt_min_batch_time, Opt_max_batch_time,
        Opt_journal_update, Opt_journal_dev,
        Opt_journal_checksum, Opt_journal_async_commit,
@@ -1026,8 +1026,8 @@ enum {
        Opt_data_err_abort, Opt_data_err_ignore,
        Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,
        Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_quota, Opt_noquota,
-       Opt_ignore, Opt_barrier, Opt_err, Opt_resize, Opt_usrquota,
-       Opt_grpquota, Opt_i_version,
+       Opt_ignore, Opt_barrier, Opt_nobarrier, Opt_err, Opt_resize,
+       Opt_usrquota, Opt_grpquota, Opt_i_version,
        Opt_stripe, Opt_delalloc, Opt_nodelalloc,
        Opt_inode_readahead_blks, Opt_journal_ioprio
 };
@@ -1080,6 +1080,8 @@ static const match_table_t tokens = {
        {Opt_quota, "quota"},
        {Opt_usrquota, "usrquota"},
        {Opt_barrier, "barrier=%u"},
+       {Opt_barrier, "barrier"},
+       {Opt_nobarrier, "nobarrier"},
        {Opt_i_version, "i_version"},
        {Opt_stripe, "stripe=%u"},
        {Opt_resize, "resize"},
@@ -1088,6 +1090,8 @@ static const match_table_t tokens = {
        {Opt_inode_readahead_blks, "inode_readahead_blks=%u"},
        {Opt_journal_ioprio, "journal_ioprio=%u"},
        {Opt_auto_da_alloc, "auto_da_alloc=%u"},
+       {Opt_auto_da_alloc, "auto_da_alloc"},
+       {Opt_noauto_da_alloc, "noauto_da_alloc"},
        {Opt_err, NULL},
 };
 
@@ -1422,9 +1426,14 @@ set_qf_format:
                case Opt_abort:
                        set_opt(sbi->s_mount_opt, ABORT);
                        break;
+               case Opt_nobarrier:
+                       clear_opt(sbi->s_mount_opt, BARRIER);
+                       break;
                case Opt_barrier:
-                       if (match_int(&args[0], &option))
-                               return 0;
+                       if (match_int(&args[0], &option)) {
+                               set_opt(sbi->s_mount_opt, BARRIER);
+                               break;
+                       }
                        if (option)
                                set_opt(sbi->s_mount_opt, BARRIER);
                        else
@@ -1485,9 +1494,14 @@ set_qf_format:
                        *journal_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE,
                                                            option);
                        break;
+               case Opt_noauto_da_alloc:
+                       set_opt(sbi->s_mount_opt,NO_AUTO_DA_ALLOC);
+                       break;
                case Opt_auto_da_alloc:
-                       if (match_int(&args[0], &option))
-                               return 0;
+                       if (match_int(&args[0], &option)) {
+                               clear_opt(sbi->s_mount_opt, NO_AUTO_DA_ALLOC);
+                               break;
+                       }
                        if (option)
                                clear_opt(sbi->s_mount_opt, NO_AUTO_DA_ALLOC);
                        else