commit 8b87dc17fbc7443bf4c6c096279c35e89fb51326
author David Sterba <dsterba@suse.cz> Thu Aug 01 18:14:52 2013 +0200
committer Chris Mason <chris.mason@fusionio.com> Sun Sep 01 08:04:51 2013 -0400
tree aa53657898d003b48135fe4b959c97b48e591339
parent 9ec726775188906192f78ab9187640afd81ab996

btrfs: add mount option to set commit interval

I'ts hardcoded to 30 seconds which is fine for most users. Higher values
defer data being synced to permanent storage with obvious consequences
when the system crashes. The upper bound is not forced, but a warning is
printed if it's more than 300 seconds (5 minutes).

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

fs/btrfs/super.c

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 2cc5b80..1967903 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -321,6 +321,7 @@
 	Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
 	Opt_check_integrity, Opt_check_integrity_including_extent_data,
 	Opt_check_integrity_print_mask, Opt_fatal_errors,
+	Opt_commit_interval,
 	Opt_err,
 };
 
@@ -361,6 +362,7 @@
 	{Opt_check_integrity_including_extent_data, "check_int_data"},
 	{Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
 	{Opt_fatal_errors, "fatal_errors=%s"},
+	{Opt_commit_interval, "commit=%d"},
 	{Opt_err, NULL},
 };
 
@@ -645,6 +647,29 @@
 				goto out;
 			}
 			break;
+		case Opt_commit_interval:
+			intarg = 0;
+			ret = match_int(&args[0], &intarg);
+			if (ret < 0) {
+				printk(KERN_ERR
+					"btrfs: invalid commit interval\n");
+				ret = -EINVAL;
+				goto out;
+			}
+			if (intarg > 0) {
+				if (intarg > 300) {
+					printk(KERN_WARNING
+					    "btrfs: excessive commit interval %d\n",
+							intarg);
+				}
+				info->commit_interval = intarg;
+			} else {
+				printk(KERN_INFO
+				    "btrfs: using default commit interval %ds\n",
+				    BTRFS_DEFAULT_COMMIT_INTERVAL);
+				info->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
+			}
+			break;
 		case Opt_err:
 			printk(KERN_INFO "btrfs: unrecognized mount option "
 			       "'%s'\n", p);
@@ -981,6 +1006,8 @@
 				info->metadata_ratio);
 	if (btrfs_test_opt(root, PANIC_ON_FATAL_ERROR))
 		seq_puts(seq, ",fatal_errors=panic");
+	if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
+		seq_printf(seq, ",commit=%d", info->commit_interval);
 	return 0;
 }