1 files changed, 311 insertions, 192 deletions

diff --git a/fs/bcachefs/extents.c b/fs/bcachefs/extents.c
index 1b25f84e4b9c..1a331e539204 100644
--- a/fs/bcachefs/extents.c
+++ b/fs/bcachefs/extents.c
@@ -8,11 +8,13 @@
 
 #include "bcachefs.h"
 #include "bkey_methods.h"
+#include "btree_cache.h"
 #include "btree_gc.h"
 #include "btree_io.h"
 #include "btree_iter.h"
 #include "buckets.h"
 #include "checksum.h"
+#include "compress.h"
 #include "debug.h"
 #include "disk_groups.h"
 #include "error.h"
@@ -162,17 +164,19 @@ int bch2_bkey_pick_read_device(struct bch_fs *c, struct bkey_s_c k,
 
 /* KEY_TYPE_btree_ptr: */
 
-int bch2_btree_ptr_invalid(const struct bch_fs *c, struct bkey_s_c k,
+int bch2_btree_ptr_invalid(struct bch_fs *c, struct bkey_s_c k,
 			   enum bkey_invalid_flags flags,
 			   struct printbuf *err)
 {
-	if (bkey_val_u64s(k.k) > BCH_REPLICAS_MAX) {
-		prt_printf(err, "value too big (%zu > %u)",
-		       bkey_val_u64s(k.k), BCH_REPLICAS_MAX);
-		return -BCH_ERR_invalid_bkey;
-	}
+	int ret = 0;
+
+	bkey_fsck_err_on(bkey_val_u64s(k.k) > BCH_REPLICAS_MAX, c, err,
+			 btree_ptr_val_too_big,
+			 "value too big (%zu > %u)", bkey_val_u64s(k.k), BCH_REPLICAS_MAX);
 
-	return bch2_bkey_ptrs_invalid(c, k, flags, err);
+	ret = bch2_bkey_ptrs_invalid(c, k, flags, err);
+fsck_err:
+	return ret;
 }
 
 void bch2_btree_ptr_to_text(struct printbuf *out, struct bch_fs *c,
@@ -181,17 +185,25 @@ void bch2_btree_ptr_to_text(struct printbuf *out, struct bch_fs *c,
 	bch2_bkey_ptrs_to_text(out, c, k);
 }
 
-int bch2_btree_ptr_v2_invalid(const struct bch_fs *c, struct bkey_s_c k,
+int bch2_btree_ptr_v2_invalid(struct bch_fs *c, struct bkey_s_c k,
 			      enum bkey_invalid_flags flags,
 			      struct printbuf *err)
 {
-	if (bkey_val_u64s(k.k) > BKEY_BTREE_PTR_VAL_U64s_MAX) {
-		prt_printf(err, "value too big (%zu > %zu)",
-		       bkey_val_u64s(k.k), BKEY_BTREE_PTR_VAL_U64s_MAX);
-		return -BCH_ERR_invalid_bkey;
-	}
+	struct bkey_s_c_btree_ptr_v2 bp = bkey_s_c_to_btree_ptr_v2(k);
+	int ret = 0;
+
+	bkey_fsck_err_on(bkey_val_u64s(k.k) > BKEY_BTREE_PTR_VAL_U64s_MAX,
+			 c, err, btree_ptr_v2_val_too_big,
+			 "value too big (%zu > %zu)",
+			 bkey_val_u64s(k.k), BKEY_BTREE_PTR_VAL_U64s_MAX);
 
-	return bch2_bkey_ptrs_invalid(c, k, flags, err);
+	bkey_fsck_err_on(bpos_ge(bp.v->min_key, bp.k->p),
+			 c, err, btree_ptr_v2_min_key_bad,
+			 "min_key > key");
+
+	ret = bch2_bkey_ptrs_invalid(c, k, flags, err);
+fsck_err:
+	return ret;
 }
 
 void bch2_btree_ptr_v2_to_text(struct printbuf *out, struct bch_fs *c,
@@ -372,19 +384,18 @@ bool bch2_extent_merge(struct bch_fs *c, struct bkey_s l, struct bkey_s_c r)
 
 /* KEY_TYPE_reservation: */
 
-int bch2_reservation_invalid(const struct bch_fs *c, struct bkey_s_c k,
+int bch2_reservation_invalid(struct bch_fs *c, struct bkey_s_c k,
 			     enum bkey_invalid_flags flags,
 			     struct printbuf *err)
 {
 	struct bkey_s_c_reservation r = bkey_s_c_to_reservation(k);
+	int ret = 0;
 
-	if (!r.v->nr_replicas || r.v->nr_replicas > BCH_REPLICAS_MAX) {
-		prt_printf(err, "invalid nr_replicas (%u)",
-		       r.v->nr_replicas);
-		return -BCH_ERR_invalid_bkey;
-	}
-
-	return 0;
+	bkey_fsck_err_on(!r.v->nr_replicas || r.v->nr_replicas > BCH_REPLICAS_MAX, c, err,
+			 reservation_key_nr_replicas_invalid,
+			 "invalid nr_replicas (%u)", r.v->nr_replicas);
+fsck_err:
+	return ret;
 }
 
 void bch2_reservation_to_text(struct printbuf *out, struct bch_fs *c,
@@ -644,37 +655,31 @@ unsigned bch2_bkey_replicas(struct bch_fs *c, struct bkey_s_c k)
 	return replicas;
 }
 
-unsigned bch2_extent_ptr_desired_durability(struct bch_fs *c, struct extent_ptr_decoded *p)
+static inline unsigned __extent_ptr_durability(struct bch_dev *ca, struct extent_ptr_decoded *p)
 {
-	struct bch_dev *ca;
-
 	if (p->ptr.cached)
 		return 0;
 
-	ca = bch_dev_bkey_exists(c, p->ptr.dev);
-
-	return ca->mi.durability +
-		(p->has_ec
-		 ? p->ec.redundancy
-		 : 0);
+	return p->has_ec
+		? p->ec.redundancy + 1
+		: ca->mi.durability;
 }
 
-unsigned bch2_extent_ptr_durability(struct bch_fs *c, struct extent_ptr_decoded *p)
+unsigned bch2_extent_ptr_desired_durability(struct bch_fs *c, struct extent_ptr_decoded *p)
 {
-	struct bch_dev *ca;
+	struct bch_dev *ca = bch_dev_bkey_exists(c, p->ptr.dev);
 
-	if (p->ptr.cached)
-		return 0;
+	return __extent_ptr_durability(ca, p);
+}
 
-	ca = bch_dev_bkey_exists(c, p->ptr.dev);
+unsigned bch2_extent_ptr_durability(struct bch_fs *c, struct extent_ptr_decoded *p)
+{
+	struct bch_dev *ca = bch_dev_bkey_exists(c, p->ptr.dev);
 
 	if (ca->mi.state == BCH_MEMBER_STATE_failed)
 		return 0;
 
-	return ca->mi.durability +
-		(p->has_ec
-		 ? p->ec.redundancy
-		 : 0);
+	return __extent_ptr_durability(ca, p);
 }
 
 unsigned bch2_bkey_durability(struct bch_fs *c, struct bkey_s_c k)
@@ -757,18 +762,6 @@ static union bch_extent_entry *extent_entry_prev(struct bkey_ptrs ptrs,
 	return i;
 }
 
-static void extent_entry_drop(struct bkey_s k, union bch_extent_entry *entry)
-{
-	union bch_extent_entry *next = extent_entry_next(entry);
-
-	/* stripes have ptrs, but their layout doesn't work with this code */
-	BUG_ON(k.k->type == KEY_TYPE_stripe);
-
-	memmove_u64s_down(entry, next,
-			  (u64 *) bkey_val_end(k) - (u64 *) next);
-	k.k->u64s -= (u64 *) next - (u64 *) entry;
-}
-
 /*
  * Returns pointer to the next entry after the one being dropped:
  */
@@ -856,7 +849,6 @@ void bch2_bkey_drop_device_noerror(struct bkey_s k, unsigned dev)
 const struct bch_extent_ptr *bch2_bkey_has_device_c(struct bkey_s_c k, unsigned dev)
 {
 	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
-	const struct bch_extent_ptr *ptr;
 
 	bkey_for_each_ptr(ptrs, ptr)
 		if (ptr->dev == dev)
@@ -868,7 +860,6 @@ const struct bch_extent_ptr *bch2_bkey_has_device_c(struct bkey_s_c k, unsigned
 bool bch2_bkey_has_target(struct bch_fs *c, struct bkey_s_c k, unsigned target)
 {
 	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
-	const struct bch_extent_ptr *ptr;
 
 	bkey_for_each_ptr(ptrs, ptr)
 		if (bch2_dev_in_target(c, ptr->dev, target) &&
@@ -987,15 +978,38 @@ bool bch2_extent_normalize(struct bch_fs *c, struct bkey_s k)
 	return bkey_deleted(k.k);
 }
 
+void bch2_extent_ptr_to_text(struct printbuf *out, struct bch_fs *c, const struct bch_extent_ptr *ptr)
+{
+	struct bch_dev *ca = c && ptr->dev < c->sb.nr_devices && c->devs[ptr->dev]
+		? bch_dev_bkey_exists(c, ptr->dev)
+		: NULL;
+
+	if (!ca) {
+		prt_printf(out, "ptr: %u:%llu gen %u%s", ptr->dev,
+			   (u64) ptr->offset, ptr->gen,
+			   ptr->cached ? " cached" : "");
+	} else {
+		u32 offset;
+		u64 b = sector_to_bucket_and_offset(ca, ptr->offset, &offset);
+
+		prt_printf(out, "ptr: %u:%llu:%u gen %u",
+			   ptr->dev, b, offset, ptr->gen);
+		if (ptr->cached)
+			prt_str(out, " cached");
+		if (ptr->unwritten)
+			prt_str(out, " unwritten");
+		if (b >= ca->mi.first_bucket &&
+		    b <  ca->mi.nbuckets &&
+		    ptr_stale(ca, ptr))
+			prt_printf(out, " stale");
+	}
+}
+
 void bch2_bkey_ptrs_to_text(struct printbuf *out, struct bch_fs *c,
 			    struct bkey_s_c k)
 {
 	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
 	const union bch_extent_entry *entry;
-	struct bch_extent_crc_unpacked crc;
-	const struct bch_extent_ptr *ptr;
-	const struct bch_extent_stripe_ptr *ec;
-	struct bch_dev *ca;
 	bool first = true;
 
 	if (c)
@@ -1007,47 +1021,43 @@ void bch2_bkey_ptrs_to_text(struct printbuf *out, struct bch_fs *c,
 
 		switch (__extent_entry_type(entry)) {
 		case BCH_EXTENT_ENTRY_ptr:
-			ptr = entry_to_ptr(entry);
-			ca = c && ptr->dev < c->sb.nr_devices && c->devs[ptr->dev]
-				? bch_dev_bkey_exists(c, ptr->dev)
-				: NULL;
-
-			if (!ca) {
-				prt_printf(out, "ptr: %u:%llu gen %u%s", ptr->dev,
-				       (u64) ptr->offset, ptr->gen,
-				       ptr->cached ? " cached" : "");
-			} else {
-				u32 offset;
-				u64 b = sector_to_bucket_and_offset(ca, ptr->offset, &offset);
-
-				prt_printf(out, "ptr: %u:%llu:%u gen %u",
-					   ptr->dev, b, offset, ptr->gen);
-				if (ptr->cached)
-					prt_str(out, " cached");
-				if (ptr->unwritten)
-					prt_str(out, " unwritten");
-				if (ca && ptr_stale(ca, ptr))
-					prt_printf(out, " stale");
-			}
+			bch2_extent_ptr_to_text(out, c, entry_to_ptr(entry));
 			break;
+
 		case BCH_EXTENT_ENTRY_crc32:
 		case BCH_EXTENT_ENTRY_crc64:
-		case BCH_EXTENT_ENTRY_crc128:
-			crc = bch2_extent_crc_unpack(k.k, entry_to_crc(entry));
+		case BCH_EXTENT_ENTRY_crc128: {
+			struct bch_extent_crc_unpacked crc =
+				bch2_extent_crc_unpack(k.k, entry_to_crc(entry));
 
-			prt_printf(out, "crc: c_size %u size %u offset %u nonce %u csum %s compress %s",
+			prt_printf(out, "crc: c_size %u size %u offset %u nonce %u csum ",
 			       crc.compressed_size,
 			       crc.uncompressed_size,
-			       crc.offset, crc.nonce,
-			       bch2_csum_types[crc.csum_type],
-			       bch2_compression_types[crc.compression_type]);
+			       crc.offset, crc.nonce);
+			bch2_prt_csum_type(out, crc.csum_type);
+			prt_str(out, " compress ");
+			bch2_prt_compression_type(out, crc.compression_type);
 			break;
-		case BCH_EXTENT_ENTRY_stripe_ptr:
-			ec = &entry->stripe_ptr;
+		}
+		case BCH_EXTENT_ENTRY_stripe_ptr: {
+			const struct bch_extent_stripe_ptr *ec = &entry->stripe_ptr;
 
 			prt_printf(out, "ec: idx %llu block %u",
 			       (u64) ec->idx, ec->block);
 			break;
+		}
+		case BCH_EXTENT_ENTRY_rebalance: {
+			const struct bch_extent_rebalance *r = &entry->rebalance;
+
+			prt_str(out, "rebalance: target ");
+			if (c)
+				bch2_target_to_text(out, c, r->target);
+			else
+				prt_printf(out, "%u", r->target);
+			prt_str(out, " compression ");
+			bch2_compression_opt_to_text(out, r->compression);
+			break;
+		}
 		default:
 			prt_printf(out, "(invalid extent entry %.16llx)", *((u64 *) entry));
 			return;
@@ -1057,7 +1067,7 @@ void bch2_bkey_ptrs_to_text(struct printbuf *out, struct bch_fs *c,
 	}
 }
 
-static int extent_ptr_invalid(const struct bch_fs *c,
+static int extent_ptr_invalid(struct bch_fs *c,
 			      struct bkey_s_c k,
 			      enum bkey_invalid_flags flags,
 			      const struct bch_extent_ptr *ptr,
@@ -1066,10 +1076,10 @@ static int extent_ptr_invalid(const struct bch_fs *c,
 			      struct printbuf *err)
 {
 	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
-	const struct bch_extent_ptr *ptr2;
 	u64 bucket;
 	u32 bucket_offset;
 	struct bch_dev *ca;
+	int ret = 0;
 
 	if (!bch2_dev_exists2(c, ptr->dev)) {
 		/*
@@ -1080,41 +1090,33 @@ static int extent_ptr_invalid(const struct bch_fs *c,
 		if (flags & BKEY_INVALID_WRITE)
 			return 0;
 
-		prt_printf(err, "pointer to invalid device (%u)", ptr->dev);
-		return -BCH_ERR_invalid_bkey;
+		bkey_fsck_err(c, err, ptr_to_invalid_device,
+			   "pointer to invalid device (%u)", ptr->dev);
 	}
 
 	ca = bch_dev_bkey_exists(c, ptr->dev);
 	bkey_for_each_ptr(ptrs, ptr2)
-		if (ptr != ptr2 && ptr->dev == ptr2->dev) {
-			prt_printf(err, "multiple pointers to same device (%u)", ptr->dev);
-			return -BCH_ERR_invalid_bkey;
-		}
+		bkey_fsck_err_on(ptr != ptr2 && ptr->dev == ptr2->dev, c, err,
+				 ptr_to_duplicate_device,
+				 "multiple pointers to same device (%u)", ptr->dev);
 
 	bucket = sector_to_bucket_and_offset(ca, ptr->offset, &bucket_offset);
 
-	if (bucket >= ca->mi.nbuckets) {
-		prt_printf(err, "pointer past last bucket (%llu > %llu)",
-		       bucket, ca->mi.nbuckets);
-		return -BCH_ERR_invalid_bkey;
-	}
-
-	if (ptr->offset < bucket_to_sector(ca, ca->mi.first_bucket)) {
-		prt_printf(err, "pointer before first bucket (%llu < %u)",
-		       bucket, ca->mi.first_bucket);
-		return -BCH_ERR_invalid_bkey;
-	}
-
-	if (bucket_offset + size_ondisk > ca->mi.bucket_size) {
-		prt_printf(err, "pointer spans multiple buckets (%u + %u > %u)",
+	bkey_fsck_err_on(bucket >= ca->mi.nbuckets, c, err,
+			 ptr_after_last_bucket,
+			 "pointer past last bucket (%llu > %llu)", bucket, ca->mi.nbuckets);
+	bkey_fsck_err_on(ptr->offset < bucket_to_sector(ca, ca->mi.first_bucket), c, err,
+			 ptr_before_first_bucket,
+			 "pointer before first bucket (%llu < %u)", bucket, ca->mi.first_bucket);
+	bkey_fsck_err_on(bucket_offset + size_ondisk > ca->mi.bucket_size, c, err,
+			 ptr_spans_multiple_buckets,
+			 "pointer spans multiple buckets (%u + %u > %u)",
 		       bucket_offset, size_ondisk, ca->mi.bucket_size);
-		return -BCH_ERR_invalid_bkey;
-	}
-
-	return 0;
+fsck_err:
+	return ret;
 }
 
-int bch2_bkey_ptrs_invalid(const struct bch_fs *c, struct bkey_s_c k,
+int bch2_bkey_ptrs_invalid(struct bch_fs *c, struct bkey_s_c k,
 			   enum bkey_invalid_flags flags,
 			   struct printbuf *err)
 {
@@ -1124,24 +1126,22 @@ int bch2_bkey_ptrs_invalid(const struct bch_fs *c, struct bkey_s_c k,
 	unsigned size_ondisk = k.k->size;
 	unsigned nonce = UINT_MAX;
 	unsigned nr_ptrs = 0;
-	bool unwritten = false, have_ec = false, crc_since_last_ptr = false;
-	int ret;
+	bool have_written = false, have_unwritten = false, have_ec = false, crc_since_last_ptr = false;
+	int ret = 0;
 
 	if (bkey_is_btree_ptr(k.k))
 		size_ondisk = btree_sectors(c);
 
 	bkey_extent_entry_for_each(ptrs, entry) {
-		if (__extent_entry_type(entry) >= BCH_EXTENT_ENTRY_MAX) {
-			prt_printf(err, "invalid extent entry type (got %u, max %u)",
-			       __extent_entry_type(entry), BCH_EXTENT_ENTRY_MAX);
-			return -BCH_ERR_invalid_bkey;
-		}
+		bkey_fsck_err_on(__extent_entry_type(entry) >= BCH_EXTENT_ENTRY_MAX, c, err,
+			extent_ptrs_invalid_entry,
+			"invalid extent entry type (got %u, max %u)",
+			__extent_entry_type(entry), BCH_EXTENT_ENTRY_MAX);
 
-		if (bkey_is_btree_ptr(k.k) &&
-		    !extent_entry_is_ptr(entry)) {
-			prt_printf(err, "has non ptr field");
-			return -BCH_ERR_invalid_bkey;
-		}
+		bkey_fsck_err_on(bkey_is_btree_ptr(k.k) &&
+				 !extent_entry_is_ptr(entry), c, err,
+				 btree_ptr_has_non_ptr,
+				 "has non ptr field");
 
 		switch (extent_entry_type(entry)) {
 		case BCH_EXTENT_ENTRY_ptr:
@@ -1150,22 +1150,15 @@ int bch2_bkey_ptrs_invalid(const struct bch_fs *c, struct bkey_s_c k,
 			if (ret)
 				return ret;
 
-			if (nr_ptrs && unwritten != entry->ptr.unwritten) {
-				prt_printf(err, "extent with unwritten and written ptrs");
-				return -BCH_ERR_invalid_bkey;
-			}
-
-			if (k.k->type != KEY_TYPE_extent && entry->ptr.unwritten) {
-				prt_printf(err, "has unwritten ptrs");
-				return -BCH_ERR_invalid_bkey;
-			}
+			bkey_fsck_err_on(entry->ptr.cached && have_ec, c, err,
+					 ptr_cached_and_erasure_coded,
+					 "cached, erasure coded ptr");
 
-			if (entry->ptr.cached && have_ec) {
-				prt_printf(err, "cached, erasure coded ptr");
-				return -BCH_ERR_invalid_bkey;
-			}
+			if (!entry->ptr.unwritten)
+				have_written = true;
+			else
+				have_unwritten = true;
 
-			unwritten = entry->ptr.unwritten;
 			have_ec = false;
 			crc_since_last_ptr = false;
 			nr_ptrs++;
@@ -1175,72 +1168,77 @@ int bch2_bkey_ptrs_invalid(const struct bch_fs *c, struct bkey_s_c k,
 		case BCH_EXTENT_ENTRY_crc128:
 			crc = bch2_extent_crc_unpack(k.k, entry_to_crc(entry));
 
-			if (crc.offset + crc.live_size >
-			    crc.uncompressed_size) {
-				prt_printf(err, "checksum offset + key size > uncompressed size");
-				return -BCH_ERR_invalid_bkey;
-			}
-
-			size_ondisk = crc.compressed_size;
-
-			if (!bch2_checksum_type_valid(c, crc.csum_type)) {
-				prt_printf(err, "invalid checksum type");
-				return -BCH_ERR_invalid_bkey;
-			}
-
-			if (crc.compression_type >= BCH_COMPRESSION_TYPE_NR) {
-				prt_printf(err, "invalid compression type");
-				return -BCH_ERR_invalid_bkey;
-			}
+			bkey_fsck_err_on(crc.offset + crc.live_size > crc.uncompressed_size, c, err,
+					 ptr_crc_uncompressed_size_too_small,
+					 "checksum offset + key size > uncompressed size");
+			bkey_fsck_err_on(!bch2_checksum_type_valid(c, crc.csum_type), c, err,
+					 ptr_crc_csum_type_unknown,
+					 "invalid checksum type");
+			bkey_fsck_err_on(crc.compression_type >= BCH_COMPRESSION_TYPE_NR, c, err,
+					 ptr_crc_compression_type_unknown,
+					 "invalid compression type");
 
 			if (bch2_csum_type_is_encryption(crc.csum_type)) {
 				if (nonce == UINT_MAX)
 					nonce = crc.offset + crc.nonce;
-				else if (nonce != crc.offset + crc.nonce) {
-					prt_printf(err, "incorrect nonce");
-					return -BCH_ERR_invalid_bkey;
-				}
+				else if (nonce != crc.offset + crc.nonce)
+					bkey_fsck_err(c, err, ptr_crc_nonce_mismatch,
+						      "incorrect nonce");
 			}
 
-			if (crc_since_last_ptr) {
-				prt_printf(err, "redundant crc entry");
-				return -BCH_ERR_invalid_bkey;
-			}
+			bkey_fsck_err_on(crc_since_last_ptr, c, err,
+					 ptr_crc_redundant,
+					 "redundant crc entry");
 			crc_since_last_ptr = true;
+
+			bkey_fsck_err_on(crc_is_encoded(crc) &&
+					 (crc.uncompressed_size > c->opts.encoded_extent_max >> 9) &&
+					 (flags & (BKEY_INVALID_WRITE|BKEY_INVALID_COMMIT)), c, err,
+					 ptr_crc_uncompressed_size_too_big,
+					 "too large encoded extent");
+
+			size_ondisk = crc.compressed_size;
 			break;
 		case BCH_EXTENT_ENTRY_stripe_ptr:
-			if (have_ec) {
-				prt_printf(err, "redundant stripe entry");
-				return -BCH_ERR_invalid_bkey;
-			}
+			bkey_fsck_err_on(have_ec, c, err,
+					 ptr_stripe_redundant,
+					 "redundant stripe entry");
 			have_ec = true;
 			break;
-		case BCH_EXTENT_ENTRY_rebalance:
+		case BCH_EXTENT_ENTRY_rebalance: {
+			const struct bch_extent_rebalance *r = &entry->rebalance;
+
+			if (!bch2_compression_opt_valid(r->compression)) {
+				struct bch_compression_opt opt = __bch2_compression_decode(r->compression);
+				prt_printf(err, "invalid compression opt %u:%u",
+					   opt.type, opt.level);
+				return -BCH_ERR_invalid_bkey;
+			}
 			break;
 		}
+		}
 	}
 
-	if (!nr_ptrs) {
-		prt_str(err, "no ptrs");
-		return -BCH_ERR_invalid_bkey;
-	}
-
-	if (nr_ptrs >= BCH_BKEY_PTRS_MAX) {
-		prt_str(err, "too many ptrs");
-		return -BCH_ERR_invalid_bkey;
-	}
-
-	if (crc_since_last_ptr) {
-		prt_printf(err, "redundant crc entry");
-		return -BCH_ERR_invalid_bkey;
-	}
-
-	if (have_ec) {
-		prt_printf(err, "redundant stripe entry");
-		return -BCH_ERR_invalid_bkey;
-	}
-
-	return 0;
+	bkey_fsck_err_on(!nr_ptrs, c, err,
+			 extent_ptrs_no_ptrs,
+			 "no ptrs");
+	bkey_fsck_err_on(nr_ptrs > BCH_BKEY_PTRS_MAX, c, err,
+			 extent_ptrs_too_many_ptrs,
+			 "too many ptrs: %u > %u", nr_ptrs, BCH_BKEY_PTRS_MAX);
+	bkey_fsck_err_on(have_written && have_unwritten, c, err,
+			 extent_ptrs_written_and_unwritten,
+			 "extent with unwritten and written ptrs");
+	bkey_fsck_err_on(k.k->type != KEY_TYPE_extent && have_unwritten, c, err,
+			 extent_ptrs_unwritten,
+			 "has unwritten ptrs");
+	bkey_fsck_err_on(crc_since_last_ptr, c, err,
+			 extent_ptrs_redundant_crc,
+			 "redundant crc entry");
+	bkey_fsck_err_on(have_ec, c, err,
+			 extent_ptrs_redundant_stripe,
+			 "redundant stripe entry");
+fsck_err:
+	return ret;
 }
 
 void bch2_ptr_swab(struct bkey_s k)
@@ -1281,6 +1279,127 @@ void bch2_ptr_swab(struct bkey_s k)
 	}
 }
 
+const struct bch_extent_rebalance *bch2_bkey_rebalance_opts(struct bkey_s_c k)
+{
+	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
+	const union bch_extent_entry *entry;
+
+	bkey_extent_entry_for_each(ptrs, entry)
+		if (__extent_entry_type(entry) == BCH_EXTENT_ENTRY_rebalance)
+			return &entry->rebalance;
+
+	return NULL;
+}
+
+unsigned bch2_bkey_ptrs_need_rebalance(struct bch_fs *c, struct bkey_s_c k,
+				       unsigned target, unsigned compression)
+{
+	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
+	unsigned rewrite_ptrs = 0;
+
+	if (compression) {
+		unsigned compression_type = bch2_compression_opt_to_type(compression);
+		const union bch_extent_entry *entry;
+		struct extent_ptr_decoded p;
+		unsigned i = 0;
+
+		bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
+			if (p.crc.compression_type == BCH_COMPRESSION_TYPE_incompressible ||
+			    p.ptr.unwritten) {
+				rewrite_ptrs = 0;
+				goto incompressible;
+			}
+
+			if (!p.ptr.cached && p.crc.compression_type != compression_type)
+				rewrite_ptrs |= 1U << i;
+			i++;
+		}
+	}
+incompressible:
+	if (target && bch2_target_accepts_data(c, BCH_DATA_user, target)) {
+		unsigned i = 0;
+
+		bkey_for_each_ptr(ptrs, ptr) {
+			if (!ptr->cached && !bch2_dev_in_target(c, ptr->dev, target))
+				rewrite_ptrs |= 1U << i;
+			i++;
+		}
+	}
+
+	return rewrite_ptrs;
+}
+
+bool bch2_bkey_needs_rebalance(struct bch_fs *c, struct bkey_s_c k)
+{
+	const struct bch_extent_rebalance *r = bch2_bkey_rebalance_opts(k);
+
+	/*
+	 * If it's an indirect extent, we don't delete the rebalance entry when
+	 * done so that we know what options were applied - check if it still
+	 * needs work done:
+	 */
+	if (r &&
+	    k.k->type == KEY_TYPE_reflink_v &&
+	    !bch2_bkey_ptrs_need_rebalance(c, k, r->target, r->compression))
+		r = NULL;
+
+	return r != NULL;
+}
+
+int bch2_bkey_set_needs_rebalance(struct bch_fs *c, struct bkey_i *_k,
+				  struct bch_io_opts *opts)
+{
+	struct bkey_s k = bkey_i_to_s(_k);
+	struct bch_extent_rebalance *r;
+	unsigned target = opts->background_target;
+	unsigned compression = background_compression(*opts);
+	bool needs_rebalance;
+
+	if (!bkey_extent_is_direct_data(k.k))
+		return 0;
+
+	/* get existing rebalance entry: */
+	r = (struct bch_extent_rebalance *) bch2_bkey_rebalance_opts(k.s_c);
+	if (r) {
+		if (k.k->type == KEY_TYPE_reflink_v) {
+			/*
+			 * indirect extents: existing options take precedence,
+			 * so that we don't move extents back and forth if
+			 * they're referenced by different inodes with different
+			 * options:
+			 */
+			if (r->target)
+				target = r->target;
+			if (r->compression)
+				compression = r->compression;
+		}
+
+		r->target	= target;
+		r->compression	= compression;
+	}
+
+	needs_rebalance = bch2_bkey_ptrs_need_rebalance(c, k.s_c, target, compression);
+
+	if (needs_rebalance && !r) {
+		union bch_extent_entry *new = bkey_val_end(k);
+
+		new->rebalance.type		= 1U << BCH_EXTENT_ENTRY_rebalance;
+		new->rebalance.compression	= compression;
+		new->rebalance.target		= target;
+		new->rebalance.unused		= 0;
+		k.k->u64s += extent_entry_u64s(new);
+	} else if (!needs_rebalance && r && k.k->type != KEY_TYPE_reflink_v) {
+		/*
+		 * For indirect extents, don't delete the rebalance entry when
+		 * we're finished so that we know we specifically moved it or
+		 * compressed it to its current location/compression type
+		 */
+		extent_entry_drop(k, (union bch_extent_entry *) r);
+	}
+
+	return 0;
+}
+
 /* Generic extent code: */
 
 int bch2_cut_front_s(struct bpos where, struct bkey_s k)