bcachefs: RO mounts now use less memory

Defer memory allocations only needed in RW mode until we actually go RW.

This is part of improved support for RO images.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

4 files changed, 44 insertions, 24 deletions

diff --git a/fs/bcachefs/bcachefs.h b/fs/bcachefs/bcachefs.h
index 1554b79244f9..04ce43d7d1ca 100644
--- a/fs/bcachefs/bcachefs.h
+++ b/fs/bcachefs/bcachefs.h
@@ -614,6 +614,7 @@ struct bch_dev {
 	x(accounting_replay_done)	\
 	x(may_go_rw)			\
 	x(rw)				\
+	x(rw_init_done)			\
 	x(was_rw)			\
 	x(stopping)			\
 	x(emergency_ro)			\
diff --git a/fs/bcachefs/io_read.c b/fs/bcachefs/io_read.c
index 8aa0fa507983..8143037269d8 100644
--- a/fs/bcachefs/io_read.c
+++ b/fs/bcachefs/io_read.c
@@ -1484,10 +1484,18 @@ void bch2_fs_io_read_exit(struct bch_fs *c)
 		rhashtable_destroy(&c->promote_table);
 	bioset_exit(&c->bio_read_split);
 	bioset_exit(&c->bio_read);
+	mempool_exit(&c->bio_bounce_pages);
 }
 
 int bch2_fs_io_read_init(struct bch_fs *c)
 {
+	if (mempool_init_page_pool(&c->bio_bounce_pages,
+				   max_t(unsigned,
+					 c->opts.btree_node_size,
+					 c->opts.encoded_extent_max) /
+				   PAGE_SIZE, 0))
+		return -BCH_ERR_ENOMEM_bio_bounce_pages_init;
+
 	if (bioset_init(&c->bio_read, 1, offsetof(struct bch_read_bio, bio),
 			BIOSET_NEED_BVECS))
 		return -BCH_ERR_ENOMEM_bio_read_init;
diff --git a/fs/bcachefs/io_write.c b/fs/bcachefs/io_write.c
index a418fa62f09d..4dabff3ac1be 100644
--- a/fs/bcachefs/io_write.c
+++ b/fs/bcachefs/io_write.c
@@ -1723,7 +1723,6 @@ void bch2_write_op_to_text(struct printbuf *out, struct bch_write_op *op)
 
 void bch2_fs_io_write_exit(struct bch_fs *c)
 {
-	mempool_exit(&c->bio_bounce_pages);
 	bioset_exit(&c->replica_set);
 	bioset_exit(&c->bio_write);
 }
@@ -1734,12 +1733,5 @@ int bch2_fs_io_write_init(struct bch_fs *c)
 	    bioset_init(&c->replica_set, 4, offsetof(struct bch_write_bio, bio), 0))
 		return -BCH_ERR_ENOMEM_bio_write_init;
 
-	if (mempool_init_page_pool(&c->bio_bounce_pages,
-				   max_t(unsigned,
-					 c->opts.btree_node_size,
-					 c->opts.encoded_extent_max) /
-				   PAGE_SIZE, 0))
-		return -BCH_ERR_ENOMEM_bio_bounce_pages_init;
-
 	return 0;
 }
diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 348c99dbe210..f0c6fe0247a2 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -189,6 +189,7 @@ static int bch2_dev_alloc(struct bch_fs *, unsigned);
 static int bch2_dev_sysfs_online(struct bch_fs *, struct bch_dev *);
 static void bch2_dev_io_ref_stop(struct bch_dev *, int);
 static void __bch2_dev_read_only(struct bch_fs *, struct bch_dev *);
+static int bch2_fs_init_rw(struct bch_fs *);
 
 struct bch_fs *bch2_dev_to_fs(dev_t dev)
 {
@@ -466,6 +467,10 @@ static int __bch2_fs_read_write(struct bch_fs *c, bool early)
 
 	bch_info(c, "going read-write");
 
+	ret = bch2_fs_init_rw(c);
+	if (ret)
+		goto err;
+
 	ret = bch2_sb_members_v2_init(c);
 	if (ret)
 		goto err;
@@ -754,6 +759,35 @@ err:
 	return ret;
 }
 
+static int bch2_fs_init_rw(struct bch_fs *c)
+{
+	if (test_bit(BCH_FS_rw_init_done, &c->flags))
+		return 0;
+
+	if (!(c->btree_update_wq = alloc_workqueue("bcachefs",
+				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM|WQ_UNBOUND, 512)) ||
+	    !(c->btree_write_complete_wq = alloc_workqueue("bcachefs_btree_write_complete",
+				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM, 1)) ||
+	    !(c->copygc_wq = alloc_workqueue("bcachefs_copygc",
+				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE, 1)) ||
+	    !(c->btree_write_submit_wq = alloc_workqueue("bcachefs_btree_write_sumit",
+				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM, 1)) ||
+	    !(c->write_ref_wq = alloc_workqueue("bcachefs_write_ref",
+				WQ_FREEZABLE, 0)))
+		return -BCH_ERR_ENOMEM_fs_other_alloc;
+
+	int ret = bch2_fs_btree_interior_update_init(c) ?:
+		bch2_fs_btree_write_buffer_init(c) ?:
+		bch2_fs_fs_io_buffered_init(c) ?:
+		bch2_fs_io_write_init(c) ?:
+		bch2_fs_journal_init(&c->journal);
+	if (ret)
+		return ret;
+
+	set_bit(BCH_FS_rw_init_done, &c->flags);
+	return 0;
+}
+
 static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts,
 				    bch_sb_handles *sbs)
 {
@@ -919,18 +953,8 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts,
 		(btree_blocks(c) + 1) * 2 *
 		sizeof(struct sort_iter_set);
 
-	if (!(c->btree_update_wq = alloc_workqueue("bcachefs",
-				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM|WQ_UNBOUND, 512)) ||
-	    !(c->btree_write_complete_wq = alloc_workqueue("bcachefs_btree_write",
-				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM, 1)) ||
-	    !(c->copygc_wq = alloc_workqueue("bcachefs_copygc",
-				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE, 1)) ||
-	    !(c->btree_read_complete_wq = alloc_workqueue("bcachefs_btree_read_complete",
+	if (!(c->btree_read_complete_wq = alloc_workqueue("bcachefs_btree_read_complete",
 				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM, 512)) ||
-	    !(c->btree_write_submit_wq = alloc_workqueue("bcachefs_btree_write_sumit",
-				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM, 1)) ||
-	    !(c->write_ref_wq = alloc_workqueue("bcachefs_write_ref",
-				WQ_FREEZABLE, 0)) ||
 #ifndef BCH_WRITE_REF_DEBUG
 	    percpu_ref_init(&c->writes, bch2_writes_disabled,
 			    PERCPU_REF_INIT_DEAD, GFP_KERNEL) ||
@@ -953,9 +977,7 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts,
 	ret =
 	    bch2_fs_btree_cache_init(c) ?:
 	    bch2_fs_btree_iter_init(c) ?:
-	    bch2_fs_btree_interior_update_init(c) ?:
 	    bch2_fs_btree_key_cache_init(&c->btree_key_cache) ?:
-	    bch2_fs_btree_write_buffer_init(c) ?:
 	    bch2_fs_buckets_waiting_for_journal_init(c) ?:
 	    bch2_io_clock_init(&c->io_clock[READ]) ?:
 	    bch2_io_clock_init(&c->io_clock[WRITE]) ?:
@@ -964,11 +986,8 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts,
 	    bch2_fs_ec_init(c) ?:
 	    bch2_fs_encryption_init(c) ?:
 	    bch2_fs_fsio_init(c) ?:
-	    bch2_fs_fs_io_buffered_init(c) ?:
 	    bch2_fs_fs_io_direct_init(c) ?:
 	    bch2_fs_io_read_init(c) ?:
-	    bch2_fs_io_write_init(c) ?:
-	    bch2_fs_journal_init(&c->journal) ?:
 	    bch2_fs_sb_errors_init(c) ?:
 	    bch2_fs_vfs_init(c);
 	if (ret)