Btrfs: add mount -o ssd_spread to spread allocations out
Some SSDs perform best when reusing block numbers often, while
others perform much better when clustering strictly allocates
big chunks of unused space.
The default mount -o ssd will find rough groupings of blocks
where there are a bunch of free blocks that might have some
allocated blocks mixed in.
mount -o ssd_spread will make sure there are no allocated blocks
mixed in. It should perform better on lower end SSDs.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 22855a1..7f5b288 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -66,8 +66,8 @@
enum {
Opt_degraded, Opt_subvol, Opt_device, Opt_nodatasum, Opt_nodatacow,
Opt_max_extent, Opt_max_inline, Opt_alloc_start, Opt_nobarrier,
- Opt_ssd, Opt_nossd, Opt_thread_pool, Opt_noacl, Opt_compress,
- Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_err,
+ Opt_ssd, Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl,
+ Opt_compress, Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_err,
};
static match_table_t tokens = {
@@ -83,6 +83,7 @@
{Opt_thread_pool, "thread_pool=%d"},
{Opt_compress, "compress"},
{Opt_ssd, "ssd"},
+ {Opt_ssd_spread, "ssd_spread"},
{Opt_nossd, "nossd"},
{Opt_noacl, "noacl"},
{Opt_notreelog, "notreelog"},
@@ -174,9 +175,17 @@
printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
btrfs_set_opt(info->mount_opt, SSD);
break;
+ case Opt_ssd_spread:
+ printk(KERN_INFO "btrfs: use spread ssd "
+ "allocation scheme\n");
+ btrfs_set_opt(info->mount_opt, SSD);
+ btrfs_set_opt(info->mount_opt, SSD_SPREAD);
+ break;
case Opt_nossd:
- printk(KERN_INFO "btrfs: not using ssd allocation scheme\n");
+ printk(KERN_INFO "btrfs: not using ssd allocation "
+ "scheme\n");
btrfs_clear_opt(info->mount_opt, SSD);
+ btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
break;
case Opt_nobarrier:
printk(KERN_INFO "btrfs: turning off barriers\n");
@@ -429,7 +438,9 @@
seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
if (btrfs_test_opt(root, COMPRESS))
seq_puts(seq, ",compress");
- if (btrfs_test_opt(root, SSD))
+ if (btrfs_test_opt(root, SSD_SPREAD))
+ seq_puts(seq, ",ssd_spread");
+ else if (btrfs_test_opt(root, SSD))
seq_puts(seq, ",ssd");
if (btrfs_test_opt(root, NOTREELOG))
seq_puts(seq, ",notreelog");