f2fs: add nobarrier mount option

This patch adds a mount option, nobarrier, in f2fs.
The assumption in here is that file system keeps the IO ordering, but
doesn't care about cache flushes inside the storages.

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

5 files changed, 20 insertions, 1 deletions

diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt
index 51afba17bbae..a2046a7d0a9d 100644
--- a/Documentation/filesystems/f2fs.txt
+++ b/Documentation/filesystems/f2fs.txt
@@ -126,6 +126,11 @@ flush_merge	       Merge concurrent cache_flush commands as much as possible
                        to eliminate redundant command issues. If the underlying
                        device handles the cache_flush command relatively slowly,
                        recommend to enable this option.
+nobarrier              This option can be used if underlying storage guarantees
+                       its cached data should be written to the novolatile area.
+                       If this option is set, no cache_flush commands are issued
+                       but f2fs still guarantees the write ordering of all the
+                       data writes.
 
 ================================================================================
 DEBUGFS ENTRIES
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index c77c66723d70..482313dd9e24 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -139,7 +139,10 @@ void f2fs_submit_merged_bio(struct f2fs_sb_info *sbi,
         /* change META to META_FLUSH in the checkpoint procedure */
         if (type >= META_FLUSH) {
                 io->fio.type = META_FLUSH;
-                io->fio.rw = WRITE_FLUSH_FUA | REQ_META | REQ_PRIO;
+                if (test_opt(sbi, NOBARRIER))
+                        io->fio.rw = WRITE_FLUSH | REQ_META | REQ_PRIO;
+                else
+                        io->fio.rw = WRITE_FLUSH_FUA | REQ_META | REQ_PRIO;
         }
         __submit_merged_bio(io);
         up_write(&io->io_rwsem);
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 8f507d4c0f71..e999eec200b7 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -41,6 +41,7 @@
 #define F2FS_MOUNT_INLINE_XATTR         0x00000080
 #define F2FS_MOUNT_INLINE_DATA          0x00000100
 #define F2FS_MOUNT_FLUSH_MERGE          0x00000200
+#define F2FS_MOUNT_NOBARRIER            0x00000400
 
 #define clear_opt(sbi, option)  (sbi->mount_opt.opt &= ~F2FS_MOUNT_##option)
 #define set_opt(sbi, option)    (sbi->mount_opt.opt |= F2FS_MOUNT_##option)
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 8a6e57d83c79..9fce0f47eb35 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -239,6 +239,9 @@ int f2fs_issue_flush(struct f2fs_sb_info *sbi)
         struct flush_cmd_control *fcc = SM_I(sbi)->cmd_control_info;
         struct flush_cmd cmd;
 
+        if (test_opt(sbi, NOBARRIER))
+                return 0;
+
         if (!test_opt(sbi, FLUSH_MERGE))
                 return blkdev_issue_flush(sbi->sb->s_bdev, GFP_KERNEL, NULL);
 
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 34649aa66e04..93593ceec175 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -52,6 +52,7 @@ enum {
         Opt_inline_xattr,
         Opt_inline_data,
         Opt_flush_merge,
+        Opt_nobarrier,
         Opt_err,
 };
 
@@ -69,6 +70,7 @@ static match_table_t f2fs_tokens = {
         {Opt_inline_xattr, "inline_xattr"},
         {Opt_inline_data, "inline_data"},
         {Opt_flush_merge, "flush_merge"},
+        {Opt_nobarrier, "nobarrier"},
         {Opt_err, NULL},
 };
 
@@ -339,6 +341,9 @@ static int parse_options(struct super_block *sb, char *options)
                 case Opt_flush_merge:
                         set_opt(sbi, FLUSH_MERGE);
                         break;
+                case Opt_nobarrier:
+                        set_opt(sbi, NOBARRIER);
+                        break;
                 default:
                         f2fs_msg(sb, KERN_ERR,
                                 "Unrecognized mount option \"%s\" or missing value",
@@ -544,6 +549,8 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
                 seq_puts(seq, ",inline_data");
         if (!f2fs_readonly(sbi->sb) && test_opt(sbi, FLUSH_MERGE))
                 seq_puts(seq, ",flush_merge");
+        if (test_opt(sbi, NOBARRIER))
+                seq_puts(seq, ",nobarrier");
         seq_printf(seq, ",active_logs=%u", sbi->active_logs);
 
         return 0;