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Commit e244a0ae authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Chris Mason
Browse files

Btrfs: add -o discard option 



Enable discard by default is not a good idea given the the trim speed
of SSD prototypes we've seen, and the carecteristics for many high-end
arrays.  Turn of discards by default and require the -o discard option
to enable them on.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 86df7eb9

fs/btrfs/ctree.h

+1 −0
Original line number Diff line number Diff line
@@ -1153,6 +1153,7 @@ struct btrfs_root { 
#define BTRFS_MOUNT_FLUSHONCOMMIT       (1 << 7)

#define BTRFS_MOUNT_SSD_SPREAD		(1 << 8)

#define BTRFS_MOUNT_NOSSD		(1 << 9)

#define BTRFS_MOUNT_DISCARD		(1 << 10)



#define btrfs_clear_opt(o, opt)		((o) &= ~BTRFS_MOUNT_##opt)

#define btrfs_set_opt(o, opt)		((o) |= BTRFS_MOUNT_##opt)

fs/btrfs/extent-tree.c

+3 −0
Original line number Diff line number Diff line
@@ -1584,6 +1584,9 @@ static int btrfs_discard_extent(struct btrfs_root *root, u64 bytenr, 
	u64 map_length = num_bytes;

	struct btrfs_multi_bio *multi = NULL;



	if (!btrfs_test_opt(root, DISCARD))

		return 0;



	/* Tell the block device(s) that the sectors can be discarded */

	ret = btrfs_map_block(&root->fs_info->mapping_tree, READ,

			      bytenr, &map_length, &multi, 0);

fs/btrfs/super.c

+6 −1
Original line number Diff line number Diff line
@@ -66,7 +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_ssd_spread, Opt_thread_pool, Opt_noacl,

	Opt_compress, Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_err,

	Opt_compress, Opt_notreelog, Opt_ratio, Opt_flushoncommit,

	Opt_discard, Opt_err,

};



static match_table_t tokens = {
@@ -88,6 +89,7 @@ static match_table_t tokens = { 
	{Opt_notreelog, "notreelog"},

	{Opt_flushoncommit, "flushoncommit"},

	{Opt_ratio, "metadata_ratio=%d"},

	{Opt_discard, "discard"},

	{Opt_err, NULL},

};
@@ -257,6 +259,9 @@ int btrfs_parse_options(struct btrfs_root *root, char *options) 
				       info->metadata_ratio);

			}

			break;

		case Opt_discard:

			btrfs_set_opt(info->mount_opt, DISCARD);

			break;

		default:

			break;

		}