Btrfs: add skip_balance mount option
Since restriper kthread starts involuntarily on mount and can suck cpu
and memory bandwidth add a mount option to forcefully skip it. The
restriper in that case hangs around in paused state and can be resumed
from userspace when it's convenient.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 9997a59..99eb2bc 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1492,6 +1492,7 @@
#define BTRFS_MOUNT_AUTO_DEFRAG (1 << 16)
#define BTRFS_MOUNT_INODE_MAP_CACHE (1 << 17)
#define BTRFS_MOUNT_RECOVERY (1 << 18)
+#define BTRFS_MOUNT_SKIP_BALANCE (1 << 19)
#define btrfs_clear_opt(o, opt) ((o) &= ~BTRFS_MOUNT_##opt)
#define btrfs_set_opt(o, opt) ((o) |= BTRFS_MOUNT_##opt)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 34a8b61..063b521 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -164,8 +164,9 @@
Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed,
- Opt_enospc_debug, Opt_subvolrootid, Opt_defrag,
- Opt_inode_cache, Opt_no_space_cache, Opt_recovery, Opt_err,
+ Opt_enospc_debug, Opt_subvolrootid, Opt_defrag, Opt_inode_cache,
+ Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
+ Opt_err,
};
static match_table_t tokens = {
@@ -200,6 +201,7 @@
{Opt_inode_cache, "inode_cache"},
{Opt_no_space_cache, "nospace_cache"},
{Opt_recovery, "recovery"},
+ {Opt_skip_balance, "skip_balance"},
{Opt_err, NULL},
};
@@ -398,6 +400,9 @@
printk(KERN_INFO "btrfs: enabling auto recovery");
btrfs_set_opt(info->mount_opt, RECOVERY);
break;
+ case Opt_skip_balance:
+ btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
+ break;
case Opt_err:
printk(KERN_INFO "btrfs: unrecognized mount option "
"'%s'\n", p);
@@ -723,6 +728,8 @@
seq_puts(seq, ",autodefrag");
if (btrfs_test_opt(root, INODE_MAP_CACHE))
seq_puts(seq, ",inode_cache");
+ if (btrfs_test_opt(root, SKIP_BALANCE))
+ seq_puts(seq, ",skip_balance");
return 0;
}
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 17e5653..e016060 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2707,15 +2707,19 @@
struct btrfs_balance_control *bctl =
(struct btrfs_balance_control *)data;
struct btrfs_fs_info *fs_info = bctl->fs_info;
- int ret;
+ int ret = 0;
mutex_lock(&fs_info->volume_mutex);
mutex_lock(&fs_info->balance_mutex);
set_balance_control(bctl);
- printk(KERN_INFO "btrfs: continuing balance\n");
- ret = btrfs_balance(bctl, NULL);
+ if (btrfs_test_opt(fs_info->tree_root, SKIP_BALANCE)) {
+ printk(KERN_INFO "btrfs: force skipping balance\n");
+ } else {
+ printk(KERN_INFO "btrfs: continuing balance\n");
+ ret = btrfs_balance(bctl, NULL);
+ }
mutex_unlock(&fs_info->balance_mutex);
mutex_unlock(&fs_info->volume_mutex);