Btrfs: add mount -o inode_cache

This makes the inode map cache default to off until we
fix the overflow problem when the free space crcs don't fit
inside a single page.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/ctree.h

@@ -1340,6 +1340,7 @@ struct btrfs_ioctl_defrag_range_args {
 #define BTRFS_MOUNT_USER_SUBVOL_RM_ALLOWED (1 << 14)
 #define BTRFS_MOUNT_ENOSPC_DEBUG	 (1 << 15)
 #define BTRFS_MOUNT_AUTO_DEFRAG		(1 << 16)
+#define BTRFS_MOUNT_INODE_MAP_CACHE	(1 << 17)
 
 #define btrfs_clear_opt(o, opt)		((o) &= ~BTRFS_MOUNT_##opt)
 #define btrfs_set_opt(o, opt)		((o) |= BTRFS_MOUNT_##opt)

fs/btrfs/free-space-cache.c

@@ -2536,6 +2536,9 @@ int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
 	int ret = 0;
 	u64 root_gen = btrfs_root_generation(&root->root_item);
 
+	if (!btrfs_test_opt(root, INODE_MAP_CACHE))
+		return 0;
+
 	/*
 	 * If we're unmounting then just return, since this does a search on the
 	 * normal root and not the commit root and we could deadlock.
@@ -2575,6 +2578,9 @@ int btrfs_write_out_ino_cache(struct btrfs_root *root,
 	struct inode *inode;
 	int ret;
 
+	if (!btrfs_test_opt(root, INODE_MAP_CACHE))
+		return 0;
+
 	inode = lookup_free_ino_inode(root, path);
 	if (IS_ERR(inode))
 		return 0;

fs/btrfs/inode-map.c

@@ -38,6 +38,9 @@ static int caching_kthread(void *data)
 	int slot;
 	int ret;
 
+	if (!btrfs_test_opt(root, INODE_MAP_CACHE))
+		return 0;
+
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;
@@ -141,6 +144,9 @@ static void start_caching(struct btrfs_root *root)
 	int ret;
 	u64 objectid;
 
+	if (!btrfs_test_opt(root, INODE_MAP_CACHE))
+		return;
+
 	spin_lock(&root->cache_lock);
 	if (root->cached != BTRFS_CACHE_NO) {
 		spin_unlock(&root->cache_lock);
@@ -178,6 +184,9 @@ static void start_caching(struct btrfs_root *root)
 
 int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
 {
+	if (!btrfs_test_opt(root, INODE_MAP_CACHE))
+		return btrfs_find_free_objectid(root, objectid);
+
 again:
 	*objectid = btrfs_find_ino_for_alloc(root);
 
@@ -201,6 +210,10 @@ void btrfs_return_ino(struct btrfs_root *root, u64 objectid)
 {
 	struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 	struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
+
+	if (!btrfs_test_opt(root, INODE_MAP_CACHE))
+		return;
+
 again:
 	if (root->cached == BTRFS_CACHE_FINISHED) {
 		__btrfs_add_free_space(ctl, objectid, 1);
@@ -250,6 +263,9 @@ void btrfs_unpin_free_ino(struct btrfs_root *root)
 	struct rb_node *n;
 	u64 count;
 
+	if (!btrfs_test_opt(root, INODE_MAP_CACHE))
+		return;
+
 	while (1) {
 		n = rb_first(rbroot);
 		if (!n)
@@ -399,9 +415,13 @@ int btrfs_save_ino_cache(struct btrfs_root *root,
 	    root != root->fs_info->tree_root)
 		return 0;
 
+	if (!btrfs_test_opt(root, INODE_MAP_CACHE))
+		return 0;
+
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;
+
 again:
 	inode = lookup_free_ino_inode(root, path);
 	if (IS_ERR(inode) && PTR_ERR(inode) != -ENOENT) {

fs/btrfs/super.c

@@ -160,7 +160,8 @@ enum {
 	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_err,
+	Opt_enospc_debug, Opt_subvolrootid, Opt_defrag,
+	Opt_inode_cache, Opt_err,
 };
 
 static match_table_t tokens = {
@@ -192,6 +193,7 @@ static match_table_t tokens = {
 	{Opt_enospc_debug, "enospc_debug"},
 	{Opt_subvolrootid, "subvolrootid=%d"},
 	{Opt_defrag, "autodefrag"},
+	{Opt_inode_cache, "inode_cache"},
 	{Opt_err, NULL},
 };
 
@@ -360,6 +362,10 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
 			printk(KERN_INFO "btrfs: enabling disk space caching\n");
 			btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 			break;
+		case Opt_inode_cache:
+			printk(KERN_INFO "btrfs: enabling inode map caching\n");
+			btrfs_set_opt(info->mount_opt, INODE_MAP_CACHE);
+			break;
 		case Opt_clear_cache:
 			printk(KERN_INFO "btrfs: force clearing of disk cache\n");
 			btrfs_set_opt(info->mount_opt, CLEAR_CACHE);