bcachefs: New and improved topology repair code

This splits out btree topology repair into a separate pass, and makes
some improvements:
 - When we have to pick which of two overlapping nodes to drop keys
   from, we use the btree node header sequence number to preserve the
   newer node

 - the gc code has been changed so that it doesn't bail out if we're
   continuing/ignoring on fsck error - this way the dump tool can skip
   running the repair pass but still walk all reachable metadata

 - add a new superblock flag indicating when a filesystem is known to
   have btree topology issues, and the topology repair pass should be
   run

 - changing the start/end of a node might mean keys in that node have to
   be deleted: this patch handles that better by splitting it out into a
   separate function and running it explicitly in the topology repair
   code, previously those keys were only being dropped when the btree
   node was read in.

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

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/bcachefs/super-io.c b/fs/bcachefs/super-io.c
index bf36a5743607..e0de6f0c0cb4 100644
--- a/fs/bcachefs/super-io.c
+++ b/fs/bcachefs/super-io.c
@@ -439,6 +439,11 @@ int bch2_sb_to_fs(struct bch_fs *c, struct bch_sb *src)
 
 	__copy_super(&c->disk_sb, src);
 
+	if (BCH_SB_HAS_ERRORS(c->disk_sb.sb))
+		set_bit(BCH_FS_ERROR, &c->flags);
+	if (BCH_SB_HAS_TOPOLOGY_ERRORS(c->disk_sb.sb))
+		set_bit(BCH_FS_TOPOLOGY_ERROR, &c->flags);
+
 	ret = bch2_sb_replicas_to_cpu_replicas(c);
 	if (ret)
 		return ret;
@@ -715,6 +720,8 @@ int bch2_write_super(struct bch_fs *c)
 
 	if (test_bit(BCH_FS_ERROR, &c->flags))
 		SET_BCH_SB_HAS_ERRORS(c->disk_sb.sb, 1);
+	if (test_bit(BCH_FS_TOPOLOGY_ERROR, &c->flags))
+		SET_BCH_SB_HAS_TOPOLOGY_ERRORS(c->disk_sb.sb, 1);
 
 	SET_BCH_SB_BIG_ENDIAN(c->disk_sb.sb, CPU_BIG_ENDIAN);