bcachefs: Fix quotas + snapshots

Now that we can reliably designate and find the master subvolume out of
a tree of snapshots, we can finally make quotas work with snapshots:

That is - quotas will now _ignore_ snapshot subvolumes, and only be in
effect for the master (non snapshot) subvolume.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/fs-io.c

@@ -333,6 +333,9 @@ static int bch2_quota_reservation_add(struct bch_fs *c,
 {
 	int ret;
 
+	if (test_bit(EI_INODE_SNAPSHOT, &inode->ei_flags))
+		return 0;
+
 	mutex_lock(&inode->ei_quota_lock);
 	ret = bch2_quota_acct(c, inode->ei_qid, Q_SPC, sectors,
 			      check_enospc ? KEY_TYPE_QUOTA_PREALLOC : KEY_TYPE_QUOTA_NOCHECK);
@@ -414,7 +417,9 @@ static void __i_sectors_acct(struct bch_fs *c, struct bch_inode_info *inode,
 	inode->v.i_blocks += sectors;
 
 #ifdef CONFIG_BCACHEFS_QUOTA
-	if (quota_res && sectors > 0) {
+	if (quota_res &&
+	    !test_bit(EI_INODE_SNAPSHOT, &inode->ei_flags) &&
+	    sectors > 0) {
 		BUG_ON(sectors > quota_res->sectors);
 		BUG_ON(sectors > inode->ei_quota_reserved);
 

fs/bcachefs/quota.c

@@ -2,6 +2,7 @@
 #include "bcachefs.h"
 #include "btree_update.h"
 #include "errcode.h"
+#include "error.h"
 #include "inode.h"
 #include "quota.h"
 #include "subvolume.h"
@@ -556,23 +557,25 @@ static int bch2_fs_quota_read_inode(struct btree_trans *trans,
 {
 	struct bch_fs *c = trans->c;
 	struct bch_inode_unpacked u;
-	struct bch_subvolume subvolume;
+	struct bch_snapshot_tree s_t;
 	int ret;
 
-	ret = bch2_snapshot_get_subvol(trans, k.k->p.snapshot, &subvolume);
+	ret = bch2_snapshot_tree_lookup(trans,
+			snapshot_t(c, k.k->p.snapshot)->tree, &s_t);
+	bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
+			"%s: snapshot tree %u not found", __func__,
+			snapshot_t(c, k.k->p.snapshot)->tree);
 	if (ret)
 		return ret;
 
-	/*
-	 * We don't do quota accounting in snapshots:
-	 */
-	if (BCH_SUBVOLUME_SNAP(&subvolume))
+	if (!s_t.master_subvol)
 		goto advance;
 
-	if (!bkey_is_inode(k.k))
-		goto advance;
-
-	ret = bch2_inode_unpack(k, &u);
+	ret = bch2_inode_find_by_inum_trans(trans,
+				(subvol_inum) {
+					le32_to_cpu(s_t.master_subvol),
+					k.k->p.offset,
+				}, &u);
 	if (ret)
 		return ret;
 
@@ -581,7 +584,7 @@ static int bch2_fs_quota_read_inode(struct btree_trans *trans,
 	bch2_quota_acct(c, bch_qid(&u), Q_INO, 1,
 			KEY_TYPE_QUOTA_NOCHECK);
 advance:
-	bch2_btree_iter_set_pos(iter, POS(iter->pos.inode, iter->pos.offset + 1));
+	bch2_btree_iter_set_pos(iter, bpos_nosnap_successor(iter->pos));
 	return 0;
 }
 

fs/bcachefs/subvolume.c

@@ -34,8 +34,8 @@ int bch2_snapshot_tree_invalid(const struct bch_fs *c, struct bkey_s_c k,
 	return 0;
 }
 
-static int snapshot_tree_lookup(struct btree_trans *trans, u32 id,
-				struct bch_snapshot_tree *s)
+int bch2_snapshot_tree_lookup(struct btree_trans *trans, u32 id,
+			      struct bch_snapshot_tree *s)
 {
 	return bch2_bkey_get_val_typed(trans, BTREE_ID_snapshot_trees, POS(0, id),
 				       BTREE_ITER_WITH_UPDATES, snapshot_tree, s);
@@ -426,7 +426,7 @@ static int snapshot_tree_ptr_good(struct btree_trans *trans,
 				  u32 snap_id, u32 tree_id)
 {
 	struct bch_snapshot_tree s_t;
-	int ret = snapshot_tree_lookup(trans, tree_id, &s_t);
+	int ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t);
 
 	if (bch2_err_matches(ret, ENOENT))
 		return 0;
@@ -462,7 +462,7 @@ static int snapshot_tree_ptr_repair(struct btree_trans *trans,
 
 	tree_id = le32_to_cpu(root.v->tree);
 
-	ret = snapshot_tree_lookup(trans, tree_id, &s_t);
+	ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t);
 	if (ret && !bch2_err_matches(ret, ENOENT))
 		return ret;
 
@@ -659,7 +659,7 @@ static int check_subvol(struct btree_trans *trans,
 		u32 snapshot_tree = snapshot_t(c, snapshot_root)->tree;
 		struct bch_snapshot_tree st;
 
-		ret = snapshot_tree_lookup(trans, snapshot_tree, &st);
+		ret = bch2_snapshot_tree_lookup(trans, snapshot_tree, &st);
 
 		bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
 				"%s: snapshot tree %u not found", __func__, snapshot_tree);

fs/bcachefs/subvolume.h

@@ -15,6 +15,8 @@ int bch2_snapshot_tree_invalid(const struct bch_fs *, struct bkey_s_c,
 	.min_val_size	= 8,					\
 })
 
+int bch2_snapshot_tree_lookup(struct btree_trans *, u32, struct bch_snapshot_tree *);
+
 void bch2_snapshot_to_text(struct printbuf *, struct bch_fs *, struct bkey_s_c);
 int bch2_snapshot_invalid(const struct bch_fs *, struct bkey_s_c,
 			  unsigned, struct printbuf *);