[PATCH 4/5] btrfs: add allocation_hint option.

[Goffredo Baroncelli <kreijack@libero.it>]

From: Goffredo Baroncelli <kreijack@inwind.it>

Add allocation_hint mount option. This option accepts the following values:

- 0 (default):  the chunks allocator ignores the disk hints
- 1:            the chunks allocator considers the disk hints

Signed-off-by: Goffredo Baroncelli <kreijack@winwind.it>
---
 fs/btrfs/ctree.h   | 12 ++++++++++++
 fs/btrfs/disk-io.c |  2 ++
 fs/btrfs/super.c   | 17 +++++++++++++++++
 3 files changed, 31 insertions(+)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 1d3c1e479f3d..5cd6d658f157 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -570,6 +570,15 @@ enum btrfs_exclusive_operation {
 	BTRFS_EXCLOP_SWAP_ACTIVATE,
 };
 
+/*
+ * allocation_hint mode
+ */
+
+enum btrfs_allocation_hint_modes {
+	BTRFS_ALLOCATION_HINT_DISABLED,
+	BTRFS_ALLOCATION_HINT_ENABLED
+};
+
 struct btrfs_fs_info {
 	u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
 	unsigned long flags;
@@ -961,6 +970,9 @@ struct btrfs_fs_info {
 		u64 zoned;
 	};
 
+	/* allocation_hint mode */
+	int allocation_hint_mode;
+
 	/* Max size to emit ZONE_APPEND write command */
 	u64 max_zone_append_size;
 
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 765deefda92b..1edd219c347c 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2794,6 +2794,8 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info)
 	fs_info->swapfile_pins = RB_ROOT;
 
 	fs_info->send_in_progress = 0;
+
+	fs_info->allocation_hint_mode = BTRFS_ALLOCATION_HINT_DISABLED;
 }
 
 static int init_mount_fs_info(struct btrfs_fs_info *fs_info, struct super_block *sb)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 022f20810089..d0c69c950cd9 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -359,6 +359,7 @@ enum {
 	Opt_thread_pool,
 	Opt_treelog, Opt_notreelog,
 	Opt_user_subvol_rm_allowed,
+	Opt_allocation_hint,
 
 	/* Rescue options */
 	Opt_rescue,
@@ -432,6 +433,7 @@ static const match_table_t tokens = {
 	{Opt_treelog, "treelog"},
 	{Opt_notreelog, "notreelog"},
 	{Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
+	{Opt_allocation_hint, "allocation_hint=%d"},
 
 	/* Rescue options */
 	{Opt_rescue, "rescue=%s"},
@@ -889,6 +891,19 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
 		case Opt_user_subvol_rm_allowed:
 			btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 			break;
+		case Opt_allocation_hint:
+			ret = match_int(&args[0], &intarg);
+			if (ret || (intarg != 1 && intarg != 0)) {
+				btrfs_err(info, "invalid allocation_hint= parameter\n");
+				ret = -EINVAL;
+				goto out;
+			}
+			if (intarg)
+				btrfs_info(info, "allocation_hint enabled");
+			else
+				btrfs_info(info, "allocation_hint disabled");
+			info->allocation_hint_mode = intarg;
+			break;
 		case Opt_enospc_debug:
 			btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 			break;
@@ -1495,6 +1510,8 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 		seq_puts(seq, ",clear_cache");
 	if (btrfs_test_opt(info, USER_SUBVOL_RM_ALLOWED))
 		seq_puts(seq, ",user_subvol_rm_allowed");
+	if (info->allocation_hint_mode)
+		seq_puts(seq, ",allocation_hint=1");
 	if (btrfs_test_opt(info, ENOSPC_DEBUG))
 		seq_puts(seq, ",enospc_debug");
 	if (btrfs_test_opt(info, AUTO_DEFRAG))
-- 
2.30.0