X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libbcachefs%2Fextents.c;h=61395b113df9bdad67c0da7d2a4cc4f99664bc4e;hb=e5b2870d05753c1dedd79261ba5e321ce953f5ab;hp=6bcc178604b0a81a3470b18b2c3742cd890d10b0;hpb=ffced87f08a9ff929f78fd941536d4f88507588a;p=bcachefs-tools-debian

diff --git a/libbcachefs/extents.c b/libbcachefs/extents.c
index 6bcc178..61395b1 100644
--- a/libbcachefs/extents.c
+++ b/libbcachefs/extents.c
@@ -8,10 +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"
@@ -21,10 +24,9 @@
 #include "replicas.h"
 #include "super.h"
 #include "super-io.h"
+#include "trace.h"
 #include "util.h"
 
-#include <trace/events/bcachefs.h>
-
 static unsigned bch2_crc_field_size_max[] = {
 	[BCH_EXTENT_ENTRY_crc32] = CRC32_SIZE_MAX,
 	[BCH_EXTENT_ENTRY_crc64] = CRC64_SIZE_MAX,
@@ -88,7 +90,7 @@ static inline bool ptr_better(struct bch_fs *c,
 		return bch2_rand_range(l1 + l2) > l1;
 	}
 
-	if (force_reconstruct_read(c))
+	if (bch2_force_reconstruct_read)
 		return p1.idx > p2.idx;
 
 	return p1.idx < p2.idx;
@@ -114,6 +116,13 @@ int bch2_bkey_pick_read_device(struct bch_fs *c, struct bkey_s_c k,
 		return -EIO;
 
 	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
+		/*
+		 * Unwritten extent: no need to actually read, treat it as a
+		 * hole and return 0s:
+		 */
+		if (p.ptr.unwritten)
+			return 0;
+
 		ca = bch_dev_bkey_exists(c, p.ptr.dev);
 
 		/*
@@ -136,7 +145,7 @@ int bch2_bkey_pick_read_device(struct bch_fs *c, struct bkey_s_c k,
 		    !bch2_dev_is_readable(ca))
 			p.idx++;
 
-		if (force_reconstruct_read(c) &&
+		if (bch2_force_reconstruct_read &&
 		    !p.idx && p.has_ec)
 			p.idx++;
 
@@ -155,52 +164,19 @@ int bch2_bkey_pick_read_device(struct bch_fs *c, struct bkey_s_c k,
 
 /* KEY_TYPE_btree_ptr: */
 
-const char *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) > BKEY_BTREE_PTR_VAL_U64s_MAX)
-		return "value too big";
-
-	return bch2_bkey_ptrs_invalid(c, k);
-}
-
-void bch2_btree_ptr_debugcheck(struct bch_fs *c, struct bkey_s_c k)
-{
-	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
-	const struct bch_extent_ptr *ptr;
-	const char *err;
-	char buf[160];
-	struct bucket_mark mark;
-	struct bch_dev *ca;
-
-	bch2_fs_bug_on(!test_bit(BCH_FS_REBUILD_REPLICAS, &c->flags) &&
-		       !bch2_bkey_replicas_marked(c, k, false), c,
-		       "btree key bad (replicas not marked in superblock):\n%s",
-		       (bch2_bkey_val_to_text(&PBUF(buf), c, k), buf));
-
-	if (!test_bit(BCH_FS_INITIAL_GC_DONE, &c->flags))
-		return;
-
-	bkey_for_each_ptr(ptrs, ptr) {
-		ca = bch_dev_bkey_exists(c, ptr->dev);
-
-		mark = ptr_bucket_mark(ca, ptr);
-
-		err = "stale";
-		if (gen_after(mark.gen, ptr->gen))
-			goto err;
+	int ret = 0;
 
-		err = "inconsistent";
-		if (mark.data_type != BCH_DATA_BTREE ||
-		    mark.dirty_sectors < c->opts.btree_node_size)
-			goto err;
-	}
+	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;
-err:
-	bch2_bkey_val_to_text(&PBUF(buf), c, k);
-	bch2_fs_bug(c, "%s btree pointer %s: bucket %zi gen %i mark %08x",
-		    err, buf, PTR_BUCKET_NR(ca, ptr),
-		    mark.gen, (unsigned) mark.v.counter);
+	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,
@@ -209,196 +185,212 @@ void bch2_btree_ptr_to_text(struct printbuf *out, struct bch_fs *c,
 	bch2_bkey_ptrs_to_text(out, c, k);
 }
 
-/* KEY_TYPE_extent: */
-
-const char *bch2_extent_invalid(const struct bch_fs *c, struct bkey_s_c k)
-{
-	return bch2_bkey_ptrs_invalid(c, k);
-}
-
-void bch2_extent_debugcheck(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)
 {
-	struct bkey_s_c_extent e = bkey_s_c_to_extent(k);
-	const union bch_extent_entry *entry;
-	struct extent_ptr_decoded p;
-	char buf[160];
+	int ret = 0;
 
-	/*
-	 * XXX: we should be doing most/all of these checks at startup time,
-	 * where we check bch2_bkey_invalid() in btree_node_read_done()
-	 *
-	 * But note that we can't check for stale pointers or incorrect gc marks
-	 * until after journal replay is done (it might be an extent that's
-	 * going to get overwritten during replay)
-	 */
+	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);
 
-	if (percpu_down_read_trylock(&c->mark_lock)) {
-		bch2_fs_bug_on(!test_bit(BCH_FS_REBUILD_REPLICAS, &c->flags) &&
-			       !bch2_bkey_replicas_marked_locked(c, e.s_c, false), c,
-			       "extent key bad (replicas not marked in superblock):\n%s",
-			       (bch2_bkey_val_to_text(&PBUF(buf), c, e.s_c), buf));
-		percpu_up_read(&c->mark_lock);
-	}
-	/*
-	 * If journal replay hasn't finished, we might be seeing keys
-	 * that will be overwritten by the time journal replay is done:
-	 */
-	if (!test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags))
-		return;
-
-	extent_for_each_ptr_decode(e, p, entry) {
-		struct bch_dev *ca	= bch_dev_bkey_exists(c, p.ptr.dev);
-		struct bucket_mark mark = ptr_bucket_mark(ca, &p.ptr);
-		unsigned stale		= gen_after(mark.gen, p.ptr.gen);
-		unsigned disk_sectors	= ptr_disk_sectors(p);
-		unsigned mark_sectors	= p.ptr.cached
-			? mark.cached_sectors
-			: mark.dirty_sectors;
-
-		bch2_fs_bug_on(stale && !p.ptr.cached, c,
-			       "stale dirty pointer (ptr gen %u bucket %u",
-			       p.ptr.gen, mark.gen);
-
-		bch2_fs_bug_on(stale > 96, c, "key too stale: %i", stale);
-
-		bch2_fs_bug_on(!stale &&
-			       (mark.data_type != BCH_DATA_USER ||
-				mark_sectors < disk_sectors), c,
-			       "extent pointer not marked: %s:\n"
-			       "type %u sectors %u < %u",
-			       (bch2_bkey_val_to_text(&PBUF(buf), c, e.s_c), buf),
-			       mark.data_type,
-			       mark_sectors, disk_sectors);
-	}
+	ret = bch2_bkey_ptrs_invalid(c, k, flags, err);
+fsck_err:
+	return ret;
 }
 
-void bch2_extent_to_text(struct printbuf *out, struct bch_fs *c,
-			 struct bkey_s_c k)
+void bch2_btree_ptr_v2_to_text(struct printbuf *out, struct bch_fs *c,
+			       struct bkey_s_c k)
 {
+	struct bkey_s_c_btree_ptr_v2 bp = bkey_s_c_to_btree_ptr_v2(k);
+
+	prt_printf(out, "seq %llx written %u min_key %s",
+	       le64_to_cpu(bp.v->seq),
+	       le16_to_cpu(bp.v->sectors_written),
+	       BTREE_PTR_RANGE_UPDATED(bp.v) ? "R " : "");
+
+	bch2_bpos_to_text(out, bp.v->min_key);
+	prt_printf(out, " ");
 	bch2_bkey_ptrs_to_text(out, c, k);
 }
 
-enum merge_result bch2_extent_merge(struct bch_fs *c,
-				    struct bkey_s _l, struct bkey_s _r)
+void bch2_btree_ptr_v2_compat(enum btree_id btree_id, unsigned version,
+			      unsigned big_endian, int write,
+			      struct bkey_s k)
 {
-	struct bkey_s_extent l = bkey_s_to_extent(_l);
-	struct bkey_s_extent r = bkey_s_to_extent(_r);
-	union bch_extent_entry *en_l = l.v->start;
-	union bch_extent_entry *en_r = r.v->start;
-	struct bch_extent_crc_unpacked crc_l, crc_r;
-
-	if (bkey_val_u64s(l.k) != bkey_val_u64s(r.k))
-		return BCH_MERGE_NOMERGE;
+	struct bkey_s_btree_ptr_v2 bp = bkey_s_to_btree_ptr_v2(k);
 
-	crc_l = bch2_extent_crc_unpack(l.k, NULL);
+	compat_bpos(0, btree_id, version, big_endian, write, &bp.v->min_key);
 
-	extent_for_each_entry(l, en_l) {
-		en_r = vstruct_idx(r.v, (u64 *) en_l - l.v->_data);
+	if (version < bcachefs_metadata_version_inode_btree_change &&
+	    btree_id_is_extents(btree_id) &&
+	    !bkey_eq(bp.v->min_key, POS_MIN))
+		bp.v->min_key = write
+			? bpos_nosnap_predecessor(bp.v->min_key)
+			: bpos_nosnap_successor(bp.v->min_key);
+}
 
-		if (extent_entry_type(en_l) != extent_entry_type(en_r))
-			return BCH_MERGE_NOMERGE;
+/* KEY_TYPE_extent: */
 
-		switch (extent_entry_type(en_l)) {
-		case BCH_EXTENT_ENTRY_ptr: {
-			const struct bch_extent_ptr *lp = &en_l->ptr;
-			const struct bch_extent_ptr *rp = &en_r->ptr;
-			struct bch_dev *ca;
+bool bch2_extent_merge(struct bch_fs *c, struct bkey_s l, struct bkey_s_c r)
+{
+	struct bkey_ptrs   l_ptrs = bch2_bkey_ptrs(l);
+	struct bkey_ptrs_c r_ptrs = bch2_bkey_ptrs_c(r);
+	union bch_extent_entry *en_l;
+	const union bch_extent_entry *en_r;
+	struct extent_ptr_decoded lp, rp;
+	bool use_right_ptr;
+	struct bch_dev *ca;
 
-			if (lp->offset + crc_l.compressed_size != rp->offset ||
-			    lp->dev			!= rp->dev ||
-			    lp->gen			!= rp->gen)
-				return BCH_MERGE_NOMERGE;
+	en_l = l_ptrs.start;
+	en_r = r_ptrs.start;
+	while (en_l < l_ptrs.end && en_r < r_ptrs.end) {
+		if (extent_entry_type(en_l) != extent_entry_type(en_r))
+			return false;
 
-			/* We don't allow extents to straddle buckets: */
-			ca = bch_dev_bkey_exists(c, lp->dev);
+		en_l = extent_entry_next(en_l);
+		en_r = extent_entry_next(en_r);
+	}
 
-			if (PTR_BUCKET_NR(ca, lp) != PTR_BUCKET_NR(ca, rp))
-				return BCH_MERGE_NOMERGE;
+	if (en_l < l_ptrs.end || en_r < r_ptrs.end)
+		return false;
 
-			break;
+	en_l = l_ptrs.start;
+	en_r = r_ptrs.start;
+	lp.crc = bch2_extent_crc_unpack(l.k, NULL);
+	rp.crc = bch2_extent_crc_unpack(r.k, NULL);
+
+	while (__bkey_ptr_next_decode(l.k, l_ptrs.end, lp, en_l) &&
+	       __bkey_ptr_next_decode(r.k, r_ptrs.end, rp, en_r)) {
+		if (lp.ptr.offset + lp.crc.offset + lp.crc.live_size !=
+		    rp.ptr.offset + rp.crc.offset ||
+		    lp.ptr.dev			!= rp.ptr.dev ||
+		    lp.ptr.gen			!= rp.ptr.gen ||
+		    lp.ptr.unwritten		!= rp.ptr.unwritten ||
+		    lp.has_ec			!= rp.has_ec)
+			return false;
+
+		/* Extents may not straddle buckets: */
+		ca = bch_dev_bkey_exists(c, lp.ptr.dev);
+		if (PTR_BUCKET_NR(ca, &lp.ptr) != PTR_BUCKET_NR(ca, &rp.ptr))
+			return false;
+
+		if (lp.has_ec			!= rp.has_ec ||
+		    (lp.has_ec &&
+		     (lp.ec.block		!= rp.ec.block ||
+		      lp.ec.redundancy		!= rp.ec.redundancy ||
+		      lp.ec.idx			!= rp.ec.idx)))
+			return false;
+
+		if (lp.crc.compression_type	!= rp.crc.compression_type ||
+		    lp.crc.nonce		!= rp.crc.nonce)
+			return false;
+
+		if (lp.crc.offset + lp.crc.live_size + rp.crc.live_size <=
+		    lp.crc.uncompressed_size) {
+			/* can use left extent's crc entry */
+		} else if (lp.crc.live_size <= rp.crc.offset) {
+			/* can use right extent's crc entry */
+		} else {
+			/* check if checksums can be merged: */
+			if (lp.crc.csum_type		!= rp.crc.csum_type ||
+			    lp.crc.nonce		!= rp.crc.nonce ||
+			    crc_is_compressed(lp.crc) ||
+			    !bch2_checksum_mergeable(lp.crc.csum_type))
+				return false;
+
+			if (lp.crc.offset + lp.crc.live_size != lp.crc.compressed_size ||
+			    rp.crc.offset)
+				return false;
+
+			if (lp.crc.csum_type &&
+			    lp.crc.uncompressed_size +
+			    rp.crc.uncompressed_size > (c->opts.encoded_extent_max >> 9))
+				return false;
 		}
-		case BCH_EXTENT_ENTRY_stripe_ptr:
-			if (en_l->stripe_ptr.block	!= en_r->stripe_ptr.block ||
-			    en_l->stripe_ptr.idx	!= en_r->stripe_ptr.idx)
-				return BCH_MERGE_NOMERGE;
-			break;
-		case BCH_EXTENT_ENTRY_crc32:
-		case BCH_EXTENT_ENTRY_crc64:
-		case BCH_EXTENT_ENTRY_crc128:
-			crc_l = bch2_extent_crc_unpack(l.k, entry_to_crc(en_l));
-			crc_r = bch2_extent_crc_unpack(r.k, entry_to_crc(en_r));
-
-			if (crc_l.csum_type		!= crc_r.csum_type ||
-			    crc_l.compression_type	!= crc_r.compression_type ||
-			    crc_l.nonce			!= crc_r.nonce)
-				return BCH_MERGE_NOMERGE;
-
-			if (crc_l.offset + crc_l.live_size != crc_l.compressed_size ||
-			    crc_r.offset)
-				return BCH_MERGE_NOMERGE;
-
-			if (!bch2_checksum_mergeable(crc_l.csum_type))
-				return BCH_MERGE_NOMERGE;
 
-			if (crc_l.compression_type)
-				return BCH_MERGE_NOMERGE;
+		en_l = extent_entry_next(en_l);
+		en_r = extent_entry_next(en_r);
+	}
 
-			if (crc_l.csum_type &&
-			    crc_l.uncompressed_size +
-			    crc_r.uncompressed_size > c->sb.encoded_extent_max)
-				return BCH_MERGE_NOMERGE;
+	en_l = l_ptrs.start;
+	en_r = r_ptrs.start;
+	while (en_l < l_ptrs.end && en_r < r_ptrs.end) {
+		if (extent_entry_is_crc(en_l)) {
+			struct bch_extent_crc_unpacked crc_l = bch2_extent_crc_unpack(l.k, entry_to_crc(en_l));
+			struct bch_extent_crc_unpacked crc_r = bch2_extent_crc_unpack(r.k, entry_to_crc(en_r));
 
-			if (crc_l.uncompressed_size + crc_r.uncompressed_size - 1 >
+			if (crc_l.uncompressed_size + crc_r.uncompressed_size >
 			    bch2_crc_field_size_max[extent_entry_type(en_l)])
-				return BCH_MERGE_NOMERGE;
-
-			break;
-		default:
-			return BCH_MERGE_NOMERGE;
+				return false;
 		}
-	}
-
-	extent_for_each_entry(l, en_l) {
-		struct bch_extent_crc_unpacked crc_l, crc_r;
-
-		en_r = vstruct_idx(r.v, (u64 *) en_l - l.v->_data);
-
-		if (!extent_entry_is_crc(en_l))
-			continue;
 
-		crc_l = bch2_extent_crc_unpack(l.k, entry_to_crc(en_l));
-		crc_r = bch2_extent_crc_unpack(r.k, entry_to_crc(en_r));
-
-		crc_l.csum = bch2_checksum_merge(crc_l.csum_type,
-						 crc_l.csum,
-						 crc_r.csum,
-						 crc_r.uncompressed_size << 9);
+		en_l = extent_entry_next(en_l);
+		en_r = extent_entry_next(en_r);
+	}
 
-		crc_l.uncompressed_size	+= crc_r.uncompressed_size;
-		crc_l.compressed_size	+= crc_r.compressed_size;
+	use_right_ptr = false;
+	en_l = l_ptrs.start;
+	en_r = r_ptrs.start;
+	while (en_l < l_ptrs.end) {
+		if (extent_entry_type(en_l) == BCH_EXTENT_ENTRY_ptr &&
+		    use_right_ptr)
+			en_l->ptr = en_r->ptr;
+
+		if (extent_entry_is_crc(en_l)) {
+			struct bch_extent_crc_unpacked crc_l =
+				bch2_extent_crc_unpack(l.k, entry_to_crc(en_l));
+			struct bch_extent_crc_unpacked crc_r =
+				bch2_extent_crc_unpack(r.k, entry_to_crc(en_r));
+
+			use_right_ptr = false;
+
+			if (crc_l.offset + crc_l.live_size + crc_r.live_size <=
+			    crc_l.uncompressed_size) {
+				/* can use left extent's crc entry */
+			} else if (crc_l.live_size <= crc_r.offset) {
+				/* can use right extent's crc entry */
+				crc_r.offset -= crc_l.live_size;
+				bch2_extent_crc_pack(entry_to_crc(en_l), crc_r,
+						     extent_entry_type(en_l));
+				use_right_ptr = true;
+			} else {
+				crc_l.csum = bch2_checksum_merge(crc_l.csum_type,
+								 crc_l.csum,
+								 crc_r.csum,
+								 crc_r.uncompressed_size << 9);
+
+				crc_l.uncompressed_size	+= crc_r.uncompressed_size;
+				crc_l.compressed_size	+= crc_r.compressed_size;
+				bch2_extent_crc_pack(entry_to_crc(en_l), crc_l,
+						     extent_entry_type(en_l));
+			}
+		}
 
-		bch2_extent_crc_pack(entry_to_crc(en_l), crc_l,
-				     extent_entry_type(en_l));
+		en_l = extent_entry_next(en_l);
+		en_r = extent_entry_next(en_r);
 	}
 
 	bch2_key_resize(l.k, l.k->size + r.k->size);
-
-	return BCH_MERGE_MERGE;
+	return true;
 }
 
 /* KEY_TYPE_reservation: */
 
-const char *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 (bkey_val_bytes(k.k) != sizeof(struct bch_reservation))
-		return "incorrect value size";
-
-	if (!r.v->nr_replicas || r.v->nr_replicas > BCH_REPLICAS_MAX)
-		return "invalid nr_replicas";
-
-	return NULL;
+	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,
@@ -406,30 +398,22 @@ void bch2_reservation_to_text(struct printbuf *out, struct bch_fs *c,
 {
 	struct bkey_s_c_reservation r = bkey_s_c_to_reservation(k);
 
-	pr_buf(out, "generation %u replicas %u",
+	prt_printf(out, "generation %u replicas %u",
 	       le32_to_cpu(r.v->generation),
 	       r.v->nr_replicas);
 }
 
-enum merge_result bch2_reservation_merge(struct bch_fs *c,
-					 struct bkey_s _l, struct bkey_s _r)
+bool bch2_reservation_merge(struct bch_fs *c, struct bkey_s _l, struct bkey_s_c _r)
 {
 	struct bkey_s_reservation l = bkey_s_to_reservation(_l);
-	struct bkey_s_reservation r = bkey_s_to_reservation(_r);
+	struct bkey_s_c_reservation r = bkey_s_c_to_reservation(_r);
 
 	if (l.v->generation != r.v->generation ||
 	    l.v->nr_replicas != r.v->nr_replicas)
-		return BCH_MERGE_NOMERGE;
-
-	if ((u64) l.k->size + r.k->size > KEY_SIZE_MAX) {
-		bch2_key_resize(l.k, KEY_SIZE_MAX);
-		bch2_cut_front_s(l.k->p, r.s);
-		return BCH_MERGE_PARTIAL;
-	}
+		return false;
 
 	bch2_key_resize(l.k, l.k->size + r.k->size);
-
-	return BCH_MERGE_MERGE;
+	return true;
 }
 
 /* Extent checksum entries: */
@@ -451,7 +435,7 @@ static inline bool bch2_crc_unpacked_cmp(struct bch_extent_crc_unpacked l,
 static inline bool can_narrow_crc(struct bch_extent_crc_unpacked u,
 				  struct bch_extent_crc_unpacked n)
 {
-	return !u.compression_type &&
+	return !crc_is_compressed(u) &&
 		u.csum_type &&
 		u.uncompressed_size > u.live_size &&
 		bch2_csum_type_is_encryption(u.csum_type) ==
@@ -495,7 +479,7 @@ bool bch2_bkey_narrow_crcs(struct bkey_i *k, struct bch_extent_crc_unpacked n)
 	/* Find a checksum entry that covers only live data: */
 	if (!n.csum_type) {
 		bkey_for_each_crc(&k->k, ptrs, u, i)
-			if (!u.compression_type &&
+			if (!crc_is_compressed(u) &&
 			    u.csum_type &&
 			    u.live_size == u.uncompressed_size) {
 				n = u;
@@ -504,7 +488,7 @@ bool bch2_bkey_narrow_crcs(struct bkey_i *k, struct bch_extent_crc_unpacked n)
 		return false;
 	}
 found:
-	BUG_ON(n.compression_type);
+	BUG_ON(crc_is_compressed(n));
 	BUG_ON(n.offset);
 	BUG_ON(n.live_size != k->k.size);
 
@@ -513,7 +497,7 @@ restart_narrow_pointers:
 
 	bkey_for_each_ptr_decode(&k->k, ptrs, p, i)
 		if (can_narrow_crc(p.crc, n)) {
-			bch2_bkey_drop_ptr(bkey_i_to_s(k), &i->ptr);
+			bch2_bkey_drop_ptr_noerror(bkey_i_to_s(k), &i->ptr);
 			p.ptr.offset += p.crc.offset;
 			p.crc = n;
 			bch2_extent_ptr_decoded_append(k, &p);
@@ -539,13 +523,13 @@ static void bch2_extent_crc_pack(union bch_extent_crc *dst,
 	switch (type) {
 	case BCH_EXTENT_ENTRY_crc32:
 		set_common_fields(dst->crc32, src);
-		dst->crc32.csum	 = *((__le32 *) &src.csum.lo);
+		dst->crc32.csum		= (u32 __force) *((__le32 *) &src.csum.lo);
 		break;
 	case BCH_EXTENT_ENTRY_crc64:
 		set_common_fields(dst->crc64, src);
 		dst->crc64.nonce	= src.nonce;
-		dst->crc64.csum_lo	= src.csum.lo;
-		dst->crc64.csum_hi	= *((__le16 *) &src.csum.hi);
+		dst->crc64.csum_lo	= (u64 __force) src.csum.lo;
+		dst->crc64.csum_hi	= (u64 __force) *((__le16 *) &src.csum.hi);
 		break;
 	case BCH_EXTENT_ENTRY_crc128:
 		set_common_fields(dst->crc128, src);
@@ -566,15 +550,15 @@ void bch2_extent_crc_append(struct bkey_i *k,
 	enum bch_extent_entry_type type;
 
 	if (bch_crc_bytes[new.csum_type]	<= 4 &&
-	    new.uncompressed_size - 1		<= CRC32_SIZE_MAX &&
+	    new.uncompressed_size		<= CRC32_SIZE_MAX &&
 	    new.nonce				<= CRC32_NONCE_MAX)
 		type = BCH_EXTENT_ENTRY_crc32;
 	else if (bch_crc_bytes[new.csum_type]	<= 10 &&
-		   new.uncompressed_size - 1	<= CRC64_SIZE_MAX &&
+		   new.uncompressed_size	<= CRC64_SIZE_MAX &&
 		   new.nonce			<= CRC64_NONCE_MAX)
 		type = BCH_EXTENT_ENTRY_crc64;
 	else if (bch_crc_bytes[new.csum_type]	<= 16 &&
-		   new.uncompressed_size - 1	<= CRC128_SIZE_MAX &&
+		   new.uncompressed_size	<= CRC128_SIZE_MAX &&
 		   new.nonce			<= CRC128_NONCE_MAX)
 		type = BCH_EXTENT_ENTRY_crc128;
 	else
@@ -613,8 +597,7 @@ unsigned bch2_bkey_nr_ptrs_fully_allocated(struct bkey_s_c k)
 		struct extent_ptr_decoded p;
 
 		bkey_for_each_ptr_decode(k.k, ptrs, p, entry)
-			ret += !p.ptr.cached &&
-				p.crc.compression_type == BCH_COMPRESSION_NONE;
+			ret += !p.ptr.cached && !crc_is_compressed(p.crc);
 	}
 
 	return ret;
@@ -628,67 +611,70 @@ unsigned bch2_bkey_sectors_compressed(struct bkey_s_c k)
 	unsigned ret = 0;
 
 	bkey_for_each_ptr_decode(k.k, ptrs, p, entry)
-		if (!p.ptr.cached &&
-		    p.crc.compression_type != BCH_COMPRESSION_NONE)
+		if (!p.ptr.cached && crc_is_compressed(p.crc))
 			ret += p.crc.compressed_size;
 
 	return ret;
 }
 
-bool bch2_check_range_allocated(struct bch_fs *c, struct bpos pos, u64 size,
-				unsigned nr_replicas)
+bool bch2_bkey_is_incompressible(struct bkey_s_c k)
 {
-	struct btree_trans trans;
-	struct btree_iter *iter;
-	struct bpos end = pos;
-	struct bkey_s_c k;
-	bool ret = true;
-	int err;
+	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
+	const union bch_extent_entry *entry;
+	struct bch_extent_crc_unpacked crc;
 
-	end.offset += size;
+	bkey_for_each_crc(k.k, ptrs, crc, entry)
+		if (crc.compression_type == BCH_COMPRESSION_TYPE_incompressible)
+			return true;
+	return false;
+}
 
-	bch2_trans_init(&trans, c, 0, 0);
+unsigned bch2_bkey_replicas(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 extent_ptr_decoded p = { 0 };
+	unsigned replicas = 0;
 
-	for_each_btree_key(&trans, iter, BTREE_ID_EXTENTS, pos,
-			   BTREE_ITER_SLOTS, k, err) {
-		if (bkey_cmp(bkey_start_pos(k.k), end) >= 0)
-			break;
+	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
+		if (p.ptr.cached)
+			continue;
+
+		if (p.has_ec)
+			replicas += p.ec.redundancy;
+
+		replicas++;
 
-		if (nr_replicas > bch2_bkey_nr_ptrs_fully_allocated(k)) {
-			ret = false;
-			break;
-		}
 	}
-	bch2_trans_exit(&trans);
 
-	return ret;
+	return replicas;
 }
 
-static unsigned bch2_extent_ptr_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)
 {
-	unsigned durability = 0;
-	struct bch_dev *ca;
-
-	if (p.ptr.cached)
+	if (p->ptr.cached)
 		return 0;
 
-	ca = bch_dev_bkey_exists(c, p.ptr.dev);
+	return p->has_ec
+		? p->ec.redundancy + 1
+		: ca->mi.durability;
+}
 
-	if (ca->mi.state != BCH_MEMBER_STATE_FAILED)
-		durability = max_t(unsigned, durability, ca->mi.durability);
+unsigned bch2_extent_ptr_desired_durability(struct bch_fs *c, struct extent_ptr_decoded *p)
+{
+	struct bch_dev *ca = bch_dev_bkey_exists(c, p->ptr.dev);
 
-	if (p.has_ec) {
-		struct stripe *s =
-			genradix_ptr(&c->stripes[0], p.ec.idx);
+	return __extent_ptr_durability(ca, p);
+}
 
-		if (WARN_ON(!s))
-			goto out;
+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);
 
-		durability = max_t(unsigned, durability, s->nr_redundant);
-	}
-out:
-	return durability;
+	if (ca->mi.state == BCH_MEMBER_STATE_failed)
+		return 0;
+
+	return __extent_ptr_durability(ca, p);
 }
 
 unsigned bch2_bkey_durability(struct bch_fs *c, struct bkey_s_c k)
@@ -699,74 +685,32 @@ unsigned bch2_bkey_durability(struct bch_fs *c, struct bkey_s_c k)
 	unsigned durability = 0;
 
 	bkey_for_each_ptr_decode(k.k, ptrs, p, entry)
-		durability += bch2_extent_ptr_durability(c, p);
+		durability += bch2_extent_ptr_durability(c, &p);
 
 	return durability;
 }
 
-void bch2_bkey_mark_replicas_cached(struct bch_fs *c, struct bkey_s k,
-				    unsigned target,
-				    unsigned nr_desired_replicas)
+static unsigned bch2_bkey_durability_safe(struct bch_fs *c, struct bkey_s_c k)
 {
-	struct bkey_ptrs ptrs = bch2_bkey_ptrs(k);
-	union bch_extent_entry *entry;
+	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
+	const union bch_extent_entry *entry;
 	struct extent_ptr_decoded p;
-	int extra = bch2_bkey_durability(c, k.s_c) - nr_desired_replicas;
-
-	if (target && extra > 0)
-		bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
-			int n = bch2_extent_ptr_durability(c, p);
-
-			if (n && n <= extra &&
-			    !bch2_dev_in_target(c, p.ptr.dev, target)) {
-				entry->ptr.cached = true;
-				extra -= n;
-			}
-		}
-
-	if (extra > 0)
-		bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
-			int n = bch2_extent_ptr_durability(c, p);
-
-			if (n && n <= extra) {
-				entry->ptr.cached = true;
-				extra -= n;
-			}
-		}
-}
-
-void bch2_bkey_append_ptr(struct bkey_i *k,
-			  struct bch_extent_ptr ptr)
-{
-	EBUG_ON(bch2_bkey_has_device(bkey_i_to_s_c(k), ptr.dev));
-
-	switch (k->k.type) {
-	case KEY_TYPE_btree_ptr:
-	case KEY_TYPE_extent:
-		EBUG_ON(bkey_val_u64s(&k->k) >= BKEY_EXTENT_VAL_U64s_MAX);
+	unsigned durability = 0;
 
-		ptr.type = 1 << BCH_EXTENT_ENTRY_ptr;
+	bkey_for_each_ptr_decode(k.k, ptrs, p, entry)
+		if (p.ptr.dev < c->sb.nr_devices && c->devs[p.ptr.dev])
+			durability += bch2_extent_ptr_durability(c, &p);
 
-		memcpy((void *) &k->v + bkey_val_bytes(&k->k),
-		       &ptr,
-		       sizeof(ptr));
-		k->u64s++;
-		break;
-	default:
-		BUG();
-	}
+	return durability;
 }
 
-static inline void __extent_entry_insert(struct bkey_i *k,
-					 union bch_extent_entry *dst,
-					 union bch_extent_entry *new)
+void bch2_bkey_extent_entry_drop(struct bkey_i *k, union bch_extent_entry *entry)
 {
 	union bch_extent_entry *end = bkey_val_end(bkey_i_to_s(k));
+	union bch_extent_entry *next = extent_entry_next(entry);
 
-	memmove_u64s_up_small((u64 *) dst + extent_entry_u64s(new),
-			      dst, (u64 *) end - (u64 *) dst);
-	k->k.u64s += extent_entry_u64s(new);
-	memcpy(dst, new, extent_entry_bytes(new));
+	memmove_u64s(entry, next, (u64 *) end - (u64 *) next);
+	k->k.u64s -= extent_entry_u64s(entry);
 }
 
 void bch2_extent_ptr_decoded_append(struct bkey_i *k,
@@ -813,41 +757,73 @@ static union bch_extent_entry *extent_entry_prev(struct bkey_ptrs ptrs,
 	return i;
 }
 
-union bch_extent_entry *bch2_bkey_drop_ptr(struct bkey_s k,
-					   struct bch_extent_ptr *ptr)
+/*
+ * Returns pointer to the next entry after the one being dropped:
+ */
+union bch_extent_entry *bch2_bkey_drop_ptr_noerror(struct bkey_s k,
+						   struct bch_extent_ptr *ptr)
 {
 	struct bkey_ptrs ptrs = bch2_bkey_ptrs(k);
-	union bch_extent_entry *dst, *src, *prev;
+	union bch_extent_entry *entry = to_entry(ptr), *next;
+	union bch_extent_entry *ret = entry;
 	bool drop_crc = true;
 
 	EBUG_ON(ptr < &ptrs.start->ptr ||
 		ptr >= &ptrs.end->ptr);
 	EBUG_ON(ptr->type != 1 << BCH_EXTENT_ENTRY_ptr);
 
-	src = extent_entry_next(to_entry(ptr));
-	if (src != ptrs.end &&
-	    !extent_entry_is_crc(src))
-		drop_crc = false;
-
-	dst = to_entry(ptr);
-	while ((prev = extent_entry_prev(ptrs, dst))) {
-		if (extent_entry_is_ptr(prev))
+	for (next = extent_entry_next(entry);
+	     next != ptrs.end;
+	     next = extent_entry_next(next)) {
+		if (extent_entry_is_crc(next)) {
 			break;
-
-		if (extent_entry_is_crc(prev)) {
-			if (drop_crc)
-				dst = prev;
+		} else if (extent_entry_is_ptr(next)) {
+			drop_crc = false;
 			break;
 		}
+	}
+
+	extent_entry_drop(k, entry);
+
+	while ((entry = extent_entry_prev(ptrs, entry))) {
+		if (extent_entry_is_ptr(entry))
+			break;
 
-		dst = prev;
+		if ((extent_entry_is_crc(entry) && drop_crc) ||
+		    extent_entry_is_stripe_ptr(entry)) {
+			ret = (void *) ret - extent_entry_bytes(entry);
+			extent_entry_drop(k, entry);
+		}
 	}
 
-	memmove_u64s_down(dst, src,
-			  (u64 *) ptrs.end - (u64 *) src);
-	k.k->u64s -= (u64 *) src - (u64 *) dst;
+	return ret;
+}
+
+union bch_extent_entry *bch2_bkey_drop_ptr(struct bkey_s k,
+					   struct bch_extent_ptr *ptr)
+{
+	bool have_dirty = bch2_bkey_dirty_devs(k.s_c).nr;
+	union bch_extent_entry *ret =
+		bch2_bkey_drop_ptr_noerror(k, ptr);
+
+	/*
+	 * If we deleted all the dirty pointers and there's still cached
+	 * pointers, we could set the cached pointers to dirty if they're not
+	 * stale - but to do that correctly we'd need to grab an open_bucket
+	 * reference so that we don't race with bucket reuse:
+	 */
+	if (have_dirty &&
+	    !bch2_bkey_dirty_devs(k.s_c).nr) {
+		k.k->type = KEY_TYPE_error;
+		set_bkey_val_u64s(k.k, 0);
+		ret = NULL;
+	} else if (!bch2_bkey_nr_ptrs(k.s_c)) {
+		k.k->type = KEY_TYPE_deleted;
+		set_bkey_val_u64s(k.k, 0);
+		ret = NULL;
+	}
 
-	return dst;
+	return ret;
 }
 
 void bch2_bkey_drop_device(struct bkey_s k, unsigned dev)
@@ -857,11 +833,17 @@ void bch2_bkey_drop_device(struct bkey_s k, unsigned dev)
 	bch2_bkey_drop_ptrs(k, ptr, ptr->dev == dev);
 }
 
-const struct bch_extent_ptr *
-bch2_bkey_has_device(struct bkey_s_c k, unsigned dev)
+void bch2_bkey_drop_device_noerror(struct bkey_s k, unsigned dev)
+{
+	struct bch_extent_ptr *ptr = bch2_bkey_has_device(k, dev);
+
+	if (ptr)
+		bch2_bkey_drop_ptr_noerror(k, ptr);
+}
+
+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)
@@ -873,7 +855,6 @@ bch2_bkey_has_device(struct bkey_s_c k, unsigned dev)
 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) &&
@@ -901,6 +882,78 @@ bool bch2_bkey_matches_ptr(struct bch_fs *c, struct bkey_s_c k,
 	return false;
 }
 
+/*
+ * Returns true if two extents refer to the same data:
+ */
+bool bch2_extents_match(struct bkey_s_c k1, struct bkey_s_c k2)
+{
+	if (k1.k->type != k2.k->type)
+		return false;
+
+	if (bkey_extent_is_direct_data(k1.k)) {
+		struct bkey_ptrs_c ptrs1 = bch2_bkey_ptrs_c(k1);
+		struct bkey_ptrs_c ptrs2 = bch2_bkey_ptrs_c(k2);
+		const union bch_extent_entry *entry1, *entry2;
+		struct extent_ptr_decoded p1, p2;
+
+		if (bkey_extent_is_unwritten(k1) != bkey_extent_is_unwritten(k2))
+			return false;
+
+		bkey_for_each_ptr_decode(k1.k, ptrs1, p1, entry1)
+			bkey_for_each_ptr_decode(k2.k, ptrs2, p2, entry2)
+				if (p1.ptr.dev		== p2.ptr.dev &&
+				    p1.ptr.gen		== p2.ptr.gen &&
+				    (s64) p1.ptr.offset + p1.crc.offset - bkey_start_offset(k1.k) ==
+				    (s64) p2.ptr.offset + p2.crc.offset - bkey_start_offset(k2.k))
+					return true;
+
+		return false;
+	} else {
+		/* KEY_TYPE_deleted, etc. */
+		return true;
+	}
+}
+
+struct bch_extent_ptr *
+bch2_extent_has_ptr(struct bkey_s_c k1, struct extent_ptr_decoded p1, struct bkey_s k2)
+{
+	struct bkey_ptrs ptrs2 = bch2_bkey_ptrs(k2);
+	union bch_extent_entry *entry2;
+	struct extent_ptr_decoded p2;
+
+	bkey_for_each_ptr_decode(k2.k, ptrs2, p2, entry2)
+		if (p1.ptr.dev		== p2.ptr.dev &&
+		    p1.ptr.gen		== p2.ptr.gen &&
+		    (s64) p1.ptr.offset + p1.crc.offset - bkey_start_offset(k1.k) ==
+		    (s64) p2.ptr.offset + p2.crc.offset - bkey_start_offset(k2.k))
+			return &entry2->ptr;
+
+	return NULL;
+}
+
+void bch2_extent_ptr_set_cached(struct bkey_s k, struct bch_extent_ptr *ptr)
+{
+	struct bkey_ptrs ptrs = bch2_bkey_ptrs(k);
+	union bch_extent_entry *entry;
+	union bch_extent_entry *ec = NULL;
+
+	bkey_extent_entry_for_each(ptrs, entry) {
+		if (&entry->ptr == ptr) {
+			ptr->cached = true;
+			if (ec)
+				extent_entry_drop(k, ec);
+			return;
+		}
+
+		if (extent_entry_is_stripe_ptr(entry))
+			ec = entry;
+		else if (extent_entry_is_ptr(entry))
+			ec = NULL;
+	}
+
+	BUG();
+}
+
 /*
  * bch_extent_normalize - clean up an extent, dropping stale pointers etc.
  *
@@ -917,11 +970,7 @@ bool bch2_extent_normalize(struct bch_fs *c, struct bkey_s k)
 		ptr->cached &&
 		ptr_stale(bch_dev_bkey_exists(c, ptr->dev), ptr));
 
-	/* will only happen if all pointers were cached: */
-	if (!bch2_bkey_nr_ptrs(k.s_c))
-		k.k->type = KEY_TYPE_discard;
-
-	return bkey_whiteout(k.k);
+	return bkey_deleted(k.k);
 }
 
 void bch2_bkey_ptrs_to_text(struct printbuf *out, struct bch_fs *c,
@@ -929,49 +978,76 @@ void bch2_bkey_ptrs_to_text(struct printbuf *out, struct bch_fs *c,
 {
 	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)
+		prt_printf(out, "durability: %u ", bch2_bkey_durability_safe(c, k));
+
 	bkey_extent_entry_for_each(ptrs, entry) {
 		if (!first)
-			pr_buf(out, " ");
+			prt_printf(out, " ");
 
 		switch (__extent_entry_type(entry)) {
-		case BCH_EXTENT_ENTRY_ptr:
-			ptr = entry_to_ptr(entry);
-			ca = ptr->dev < c->sb.nr_devices && c->devs[ptr->dev]
+		case BCH_EXTENT_ENTRY_ptr: {
+			const struct bch_extent_ptr *ptr = entry_to_ptr(entry);
+			struct bch_dev *ca = c && ptr->dev < c->sb.nr_devices && c->devs[ptr->dev]
 				? bch_dev_bkey_exists(c, ptr->dev)
 				: NULL;
 
-			pr_buf(out, "ptr: %u:%llu gen %u%s%s", ptr->dev,
-			       (u64) ptr->offset, ptr->gen,
-			       ptr->cached ? " cached" : "",
-			       ca && ptr_stale(ca, ptr)
-			       ? " stale" : "");
+			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");
+			}
 			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));
 
-			pr_buf(out, "crc: c_size %u size %u offset %u nonce %u csum %u compress %u",
+			prt_printf(out, "crc: c_size %u size %u offset %u nonce %u csum %s compress ",
 			       crc.compressed_size,
 			       crc.uncompressed_size,
 			       crc.offset, crc.nonce,
-			       crc.csum_type,
-			       crc.compression_type);
+			       bch2_csum_types[crc.csum_type]);
+			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;
 
-			pr_buf(out, "ec: idx %llu block %u",
+			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:
-			pr_buf(out, "(invalid extent entry %.16llx)", *((u64 *) entry));
+			prt_printf(out, "(invalid extent entry %.16llx)", *((u64 *) entry));
 			return;
 		}
 
@@ -979,110 +1055,193 @@ void bch2_bkey_ptrs_to_text(struct printbuf *out, struct bch_fs *c,
 	}
 }
 
-static const char *extent_ptr_invalid(const struct bch_fs *c,
-				      struct bkey_s_c k,
-				      const struct bch_extent_ptr *ptr,
-				      unsigned size_ondisk,
-				      bool metadata)
+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,
+			      unsigned size_ondisk,
+			      bool metadata,
+			      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)) {
+		/*
+		 * If we're in the write path this key might have already been
+		 * overwritten, and we could be seeing a device that doesn't
+		 * exist anymore due to racing with device removal:
+		 */
+		if (flags & BKEY_INVALID_WRITE)
+			return 0;
 
-	if (!bch2_dev_exists2(c, ptr->dev))
-		return "pointer to invalid device";
+		bkey_fsck_err(c, err, ptr_to_invalid_device,
+			   "pointer to invalid device (%u)", ptr->dev);
+	}
 
 	ca = bch_dev_bkey_exists(c, ptr->dev);
-	if (!ca)
-		return "pointer to invalid device";
-
 	bkey_for_each_ptr(ptrs, ptr2)
-		if (ptr != ptr2 && ptr->dev == ptr2->dev)
-			return "multiple pointers to same device";
-
-	if (ptr->offset + size_ondisk > bucket_to_sector(ca, ca->mi.nbuckets))
-		return "offset past end of device";
-
-	if (ptr->offset < bucket_to_sector(ca, ca->mi.first_bucket))
-		return "offset before first bucket";
-
-	if (bucket_remainder(ca, ptr->offset) +
-	    size_ondisk > ca->mi.bucket_size)
-		return "spans multiple buckets";
-
-	return NULL;
+		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);
+
+	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);
+fsck_err:
+	return ret;
 }
 
-const char *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)
 {
 	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
 	const union bch_extent_entry *entry;
 	struct bch_extent_crc_unpacked crc;
 	unsigned size_ondisk = k.k->size;
-	const char *reason;
 	unsigned nonce = UINT_MAX;
+	unsigned nr_ptrs = 0;
+	bool have_written = false, have_unwritten = false, have_ec = false, crc_since_last_ptr = false;
+	int ret = 0;
 
-	if (k.k->type == KEY_TYPE_btree_ptr)
-		size_ondisk = c->opts.btree_node_size;
+	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)
-			return "invalid extent entry type";
+		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 (k.k->type == KEY_TYPE_btree_ptr &&
-		    !extent_entry_is_ptr(entry))
-			return "has non ptr field";
+		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:
-			reason = extent_ptr_invalid(c, k, &entry->ptr,
-						    size_ondisk, false);
-			if (reason)
-				return reason;
+			ret = extent_ptr_invalid(c, k, flags, &entry->ptr,
+						 size_ondisk, false, err);
+			if (ret)
+				return ret;
+
+			bkey_fsck_err_on(entry->ptr.cached && have_ec, c, err,
+					 ptr_cached_and_erasure_coded,
+					 "cached, erasure coded ptr");
+
+			if (!entry->ptr.unwritten)
+				have_written = true;
+			else
+				have_unwritten = true;
+
+			have_ec = false;
+			crc_since_last_ptr = false;
+			nr_ptrs++;
 			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));
 
-			if (crc.offset + crc.live_size >
-			    crc.uncompressed_size)
-				return "checksum offset + key size > uncompressed size";
-
-			size_ondisk = crc.compressed_size;
-
-			if (!bch2_checksum_type_valid(c, crc.csum_type))
-				return "invalid checksum type";
-
-			if (crc.compression_type >= BCH_COMPRESSION_NR)
-				return "invalid compression type";
+			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)
-					return "incorrect nonce";
+					bkey_fsck_err(c, err, ptr_crc_nonce_mismatch,
+						      "incorrect nonce");
 			}
+
+			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:
+			bkey_fsck_err_on(have_ec, c, err,
+					 ptr_stripe_redundant,
+					 "redundant stripe entry");
+			have_ec = true;
+			break;
+		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;
 		}
+		}
 	}
 
-	return NULL;
+	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(const struct bkey_format *f, struct bkey_packed *k)
+void bch2_ptr_swab(struct bkey_s k)
 {
+	struct bkey_ptrs ptrs = bch2_bkey_ptrs(k);
 	union bch_extent_entry *entry;
-	u64 *d = (u64 *) bkeyp_val(f, k);
-	unsigned i;
+	u64 *d;
 
-	for (i = 0; i < bkeyp_val_u64s(f, k); i++)
-		d[i] = swab64(d[i]);
+	for (d =  (u64 *) ptrs.start;
+	     d != (u64 *) ptrs.end;
+	     d++)
+		*d = swab64(*d);
 
-	for (entry = (union bch_extent_entry *) d;
-	     entry < (union bch_extent_entry *) (d + bkeyp_val_u64s(f, k));
+	for (entry = ptrs.start;
+	     entry < ptrs.end;
 	     entry = extent_entry_next(entry)) {
 		switch (extent_entry_type(entry)) {
 		case BCH_EXTENT_ENTRY_ptr:
@@ -1102,8 +1261,131 @@ void bch2_ptr_swab(const struct bkey_format *f, struct bkey_packed *k)
 			break;
 		case BCH_EXTENT_ENTRY_stripe_ptr:
 			break;
+		case BCH_EXTENT_ENTRY_rebalance:
+			break;
+		}
+	}
+}
+
+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: */
@@ -1114,10 +1396,10 @@ int bch2_cut_front_s(struct bpos where, struct bkey_s k)
 	int val_u64s_delta;
 	u64 sub;
 
-	if (bkey_cmp(where, bkey_start_pos(k.k)) <= 0)
+	if (bkey_le(where, bkey_start_pos(k.k)))
 		return 0;
 
-	EBUG_ON(bkey_cmp(where, k.k->p) > 0);
+	EBUG_ON(bkey_gt(where, k.k->p));
 
 	sub = where.offset - bkey_start_offset(k.k);
 
@@ -1152,6 +1434,8 @@ int bch2_cut_front_s(struct bpos where, struct bkey_s k)
 				break;
 			case BCH_EXTENT_ENTRY_stripe_ptr:
 				break;
+			case BCH_EXTENT_ENTRY_rebalance:
+				break;
 			}
 
 			if (extent_entry_is_crc(entry))
@@ -1166,14 +1450,14 @@ int bch2_cut_front_s(struct bpos where, struct bkey_s k)
 		le64_add_cpu(&p.v->idx, sub);
 		break;
 	}
-	case KEY_TYPE_inline_data: {
-		struct bkey_s_inline_data d = bkey_s_to_inline_data(k);
+	case KEY_TYPE_inline_data:
+	case KEY_TYPE_indirect_inline_data: {
+		void *p = bkey_inline_data_p(k);
+		unsigned bytes = bkey_inline_data_bytes(k.k);
 
-		sub = min_t(u64, sub << 9, bkey_val_bytes(d.k));
+		sub = min_t(u64, sub << 9, bytes);
 
-		memmove(d.v->data,
-			d.v->data + sub,
-			bkey_val_bytes(d.k) - sub);
+		memmove(p, p + sub, bytes - sub);
 
 		new_val_u64s -= sub >> 3;
 		break;
@@ -1194,14 +1478,14 @@ int bch2_cut_back_s(struct bpos where, struct bkey_s k)
 	int val_u64s_delta;
 	u64 len = 0;
 
-	if (bkey_cmp(where, k.k->p) >= 0)
+	if (bkey_ge(where, k.k->p))
 		return 0;
 
-	EBUG_ON(bkey_cmp(where, bkey_start_pos(k.k)) < 0);
+	EBUG_ON(bkey_lt(where, bkey_start_pos(k.k)));
 
 	len = where.offset - bkey_start_offset(k.k);
 
-	k.k->p = where;
+	k.k->p.offset = where.offset;
 	k.k->size = len;
 
 	if (!len) {
@@ -1211,7 +1495,9 @@ int bch2_cut_back_s(struct bpos where, struct bkey_s k)
 
 	switch (k.k->type) {
 	case KEY_TYPE_inline_data:
-		new_val_u64s = min(new_val_u64s, k.k->size << 6);
+	case KEY_TYPE_indirect_inline_data:
+		new_val_u64s = (bkey_inline_data_offset(k.k) +
+				min(bkey_inline_data_bytes(k.k), k.k->size << 9)) >> 3;
 		break;
 	}