fs/bcachefs/reflink.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 #include "bcachefs.h"
 #include "bkey_buf.h"
 #include "btree_update.h"
 #include "buckets.h"
 #include "extents.h"
 #include "inode.h"
 #include "io_misc.h"
 #include "io_write.h"
 #include "reflink.h"
 #include "subvolume.h"
 #include "super-io.h"

 #include <linux/sched/signal.h>

 static inline unsigned bkey_type_to_indirect(const struct bkey *k)
 {
 	switch (k->type) {
 	case KEY_TYPE_extent:
 		return KEY_TYPE_reflink_v;
 	case KEY_TYPE_inline_data:
 		return KEY_TYPE_indirect_inline_data;
 	default:
 		return 0;
 	}
 }

 /* reflink pointers */

 int bch2_reflink_p_invalid(const struct bch_fs *c, struct bkey_s_c k,
 			   enum bkey_invalid_flags flags,
 			   struct printbuf *err)
 {
 	struct bkey_s_c_reflink_p p = bkey_s_c_to_reflink_p(k);

 	if (c->sb.version >= bcachefs_metadata_version_reflink_p_fix &&
 	    le64_to_cpu(p.v->idx) < le32_to_cpu(p.v->front_pad)) {
 		prt_printf(err, "idx < front_pad (%llu < %u)",
 		       le64_to_cpu(p.v->idx), le32_to_cpu(p.v->front_pad));
 		return -EINVAL;
 	}

 	return 0;
 }

 void bch2_reflink_p_to_text(struct printbuf *out, struct bch_fs *c,
 			    struct bkey_s_c k)
 {
 	struct bkey_s_c_reflink_p p = bkey_s_c_to_reflink_p(k);

 	prt_printf(out, "idx %llu front_pad %u back_pad %u",
 	       le64_to_cpu(p.v->idx),
 	       le32_to_cpu(p.v->front_pad),
 	       le32_to_cpu(p.v->back_pad));
 }

 bool bch2_reflink_p_merge(struct bch_fs *c, struct bkey_s _l, struct bkey_s_c _r)
 {
 	struct bkey_s_reflink_p l = bkey_s_to_reflink_p(_l);
 	struct bkey_s_c_reflink_p r = bkey_s_c_to_reflink_p(_r);

 	/*
 	 * Disabled for now, the triggers code needs to be reworked for merging
 	 * of reflink pointers to work:
 	 */
 	return false;

 	if (le64_to_cpu(l.v->idx) + l.k->size != le64_to_cpu(r.v->idx))
 		return false;

 	bch2_key_resize(l.k, l.k->size + r.k->size);
 	return true;
 }

 /* indirect extents */

 int bch2_reflink_v_invalid(const struct bch_fs *c, struct bkey_s_c k,
 			   enum bkey_invalid_flags flags,
 			   struct printbuf *err)
 {
 	return bch2_bkey_ptrs_invalid(c, k, flags, err);
 }

 void bch2_reflink_v_to_text(struct printbuf *out, struct bch_fs *c,
 			    struct bkey_s_c k)
 {
 	struct bkey_s_c_reflink_v r = bkey_s_c_to_reflink_v(k);

 	prt_printf(out, "refcount: %llu ", le64_to_cpu(r.v->refcount));

 	bch2_bkey_ptrs_to_text(out, c, k);
 }

 bool bch2_reflink_v_merge(struct bch_fs *c, struct bkey_s _l, struct bkey_s_c _r)
 {
 	struct bkey_s_reflink_v   l = bkey_s_to_reflink_v(_l);
 	struct bkey_s_c_reflink_v r = bkey_s_c_to_reflink_v(_r);

 	return l.v->refcount == r.v->refcount && bch2_extent_merge(c, _l, _r);
 }

 int bch2_trans_mark_reflink_v(struct btree_trans *trans,
 			      enum btree_id btree_id, unsigned level,
 			      struct bkey_s_c old, struct bkey_i *new,
 			      unsigned flags)
 {
 	if (!(flags & BTREE_TRIGGER_OVERWRITE)) {
 		struct bkey_i_reflink_v *r = bkey_i_to_reflink_v(new);

 		if (!r->v.refcount) {
 			r->k.type = KEY_TYPE_deleted;
 			r->k.size = 0;
 			set_bkey_val_u64s(&r->k, 0);
 			return 0;
 		}
 	}

 	return bch2_trans_mark_extent(trans, btree_id, level, old, new, flags);
 }

 /* indirect inline data */

 int bch2_indirect_inline_data_invalid(const struct bch_fs *c, struct bkey_s_c k,
 				      enum bkey_invalid_flags flags,
 				      struct printbuf *err)
 {
 	return 0;
 }

 void bch2_indirect_inline_data_to_text(struct printbuf *out,
 					struct bch_fs *c, struct bkey_s_c k)
 {
 	struct bkey_s_c_indirect_inline_data d = bkey_s_c_to_indirect_inline_data(k);
 	unsigned datalen = bkey_inline_data_bytes(k.k);

 	prt_printf(out, "refcount %llu datalen %u: %*phN",
 	       le64_to_cpu(d.v->refcount), datalen,
 	       min(datalen, 32U), d.v->data);
 }

 int bch2_trans_mark_indirect_inline_data(struct btree_trans *trans,
 			      enum btree_id btree_id, unsigned level,
 			      struct bkey_s_c old, struct bkey_i *new,
 			      unsigned flags)
 {
 	if (!(flags & BTREE_TRIGGER_OVERWRITE)) {
 		struct bkey_i_indirect_inline_data *r =
 			bkey_i_to_indirect_inline_data(new);

 		if (!r->v.refcount) {
 			r->k.type = KEY_TYPE_deleted;
 			r->k.size = 0;
 			set_bkey_val_u64s(&r->k, 0);
 		}
 	}

 	return 0;
 }

 static int bch2_make_extent_indirect(struct btree_trans *trans,
 				     struct btree_iter *extent_iter,
 				     struct bkey_i *orig)
 {
 	struct bch_fs *c = trans->c;
 	struct btree_iter reflink_iter = { NULL };
 	struct bkey_s_c k;
 	struct bkey_i *r_v;
 	struct bkey_i_reflink_p *r_p;
 	__le64 *refcount;
 	int ret;

 	if (orig->k.type == KEY_TYPE_inline_data)
 		bch2_check_set_feature(c, BCH_FEATURE_reflink_inline_data);

 	bch2_trans_iter_init(trans, &reflink_iter, BTREE_ID_reflink, POS_MAX,
 			     BTREE_ITER_INTENT);
 	k = bch2_btree_iter_peek_prev(&reflink_iter);
 	ret = bkey_err(k);
 	if (ret)
 		goto err;

 	r_v = bch2_trans_kmalloc(trans, sizeof(__le64) + bkey_bytes(&orig->k));
 	ret = PTR_ERR_OR_ZERO(r_v);
 	if (ret)
 		goto err;

 	bkey_init(&r_v->k);
 	r_v->k.type	= bkey_type_to_indirect(&orig->k);
 	r_v->k.p	= reflink_iter.pos;
 	bch2_key_resize(&r_v->k, orig->k.size);
 	r_v->k.version	= orig->k.version;

 	set_bkey_val_bytes(&r_v->k, sizeof(__le64) + bkey_val_bytes(&orig->k));

 	refcount	= bkey_refcount(r_v);
 	*refcount	= 0;
 	memcpy(refcount + 1, &orig->v, bkey_val_bytes(&orig->k));

 	ret = bch2_trans_update(trans, &reflink_iter, r_v, 0);
 	if (ret)
 		goto err;

 	/*
 	 * orig is in a bkey_buf which statically allocates 5 64s for the val,
 	 * so we know it will be big enough:
 	 */
 	orig->k.type = KEY_TYPE_reflink_p;
 	r_p = bkey_i_to_reflink_p(orig);
 	set_bkey_val_bytes(&r_p->k, sizeof(r_p->v));

 	/* FORTIFY_SOURCE is broken here, and doesn't provide unsafe_memset() */
 #if !defined(__NO_FORTIFY) && defined(__OPTIMIZE__) && defined(CONFIG_FORTIFY_SOURCE)
 	__underlying_memset(&r_p->v, 0, sizeof(r_p->v));
 #else
 	memset(&r_p->v, 0, sizeof(r_p->v));
 #endif

 	r_p->v.idx = cpu_to_le64(bkey_start_offset(&r_v->k));

 	ret = bch2_trans_update(trans, extent_iter, &r_p->k_i,
 				BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
 err:
 	bch2_trans_iter_exit(trans, &reflink_iter);

 	return ret;
 }

 static struct bkey_s_c get_next_src(struct btree_iter *iter, struct bpos end)
 {
 	struct bkey_s_c k;
 	int ret;

 	for_each_btree_key_upto_continue_norestart(*iter, end, 0, k, ret) {
 		if (bkey_extent_is_unwritten(k))
 			continue;

 		if (bkey_extent_is_data(k.k))
 			return k;
 	}

 	if (bkey_ge(iter->pos, end))
 		bch2_btree_iter_set_pos(iter, end);
 	return ret ? bkey_s_c_err(ret) : bkey_s_c_null;
 }

 s64 bch2_remap_range(struct bch_fs *c,
 		     subvol_inum dst_inum, u64 dst_offset,
 		     subvol_inum src_inum, u64 src_offset,
 		     u64 remap_sectors,
 		     u64 new_i_size, s64 *i_sectors_delta)
 {
 	struct btree_trans trans;
 	struct btree_iter dst_iter, src_iter;
 	struct bkey_s_c src_k;
 	struct bkey_buf new_dst, new_src;
 	struct bpos dst_start = POS(dst_inum.inum, dst_offset);
 	struct bpos src_start = POS(src_inum.inum, src_offset);
 	struct bpos dst_end = dst_start, src_end = src_start;
 	struct bpos src_want;
 	u64 dst_done;
 	u32 dst_snapshot, src_snapshot;
 	int ret = 0, ret2 = 0;

 	if (!bch2_write_ref_tryget(c, BCH_WRITE_REF_reflink))
 		return -BCH_ERR_erofs_no_writes;

 	bch2_check_set_feature(c, BCH_FEATURE_reflink);

 	dst_end.offset += remap_sectors;
 	src_end.offset += remap_sectors;

 	bch2_bkey_buf_init(&new_dst);
 	bch2_bkey_buf_init(&new_src);
 	bch2_trans_init(&trans, c, BTREE_ITER_MAX, 4096);

 	bch2_trans_iter_init(&trans, &src_iter, BTREE_ID_extents, src_start,
 			     BTREE_ITER_INTENT);
 	bch2_trans_iter_init(&trans, &dst_iter, BTREE_ID_extents, dst_start,
 			     BTREE_ITER_INTENT);

 	while ((ret == 0 ||
 		bch2_err_matches(ret, BCH_ERR_transaction_restart)) &&
 	       bkey_lt(dst_iter.pos, dst_end)) {
 		struct disk_reservation disk_res = { 0 };

 		bch2_trans_begin(&trans);

 		if (fatal_signal_pending(current)) {
 			ret = -EINTR;
 			break;
 		}

 		ret = bch2_subvolume_get_snapshot(&trans, src_inum.subvol,
 						  &src_snapshot);
 		if (ret)
 			continue;

 		bch2_btree_iter_set_snapshot(&src_iter, src_snapshot);

 		ret = bch2_subvolume_get_snapshot(&trans, dst_inum.subvol,
 						  &dst_snapshot);
 		if (ret)
 			continue;

 		bch2_btree_iter_set_snapshot(&dst_iter, dst_snapshot);

 		dst_done = dst_iter.pos.offset - dst_start.offset;
 		src_want = POS(src_start.inode, src_start.offset + dst_done);
 		bch2_btree_iter_set_pos(&src_iter, src_want);

 		src_k = get_next_src(&src_iter, src_end);
 		ret = bkey_err(src_k);
 		if (ret)
 			continue;

 		if (bkey_lt(src_want, src_iter.pos)) {
 			ret = bch2_fpunch_at(&trans, &dst_iter, dst_inum,
 					min(dst_end.offset,
 					    dst_iter.pos.offset +
 					    src_iter.pos.offset - src_want.offset),
 					i_sectors_delta);
 			continue;
 		}

 		if (src_k.k->type != KEY_TYPE_reflink_p) {
 			bch2_btree_iter_set_pos_to_extent_start(&src_iter);

 			bch2_bkey_buf_reassemble(&new_src, c, src_k);
 			src_k = bkey_i_to_s_c(new_src.k);

 			ret = bch2_make_extent_indirect(&trans, &src_iter,
 						new_src.k);
 			if (ret)
 				continue;

 			BUG_ON(src_k.k->type != KEY_TYPE_reflink_p);
 		}

 		if (src_k.k->type == KEY_TYPE_reflink_p) {
 			struct bkey_s_c_reflink_p src_p =
 				bkey_s_c_to_reflink_p(src_k);
 			struct bkey_i_reflink_p *dst_p =
 				bkey_reflink_p_init(new_dst.k);

 			u64 offset = le64_to_cpu(src_p.v->idx) +
 				(src_want.offset -
 				 bkey_start_offset(src_k.k));

 			dst_p->v.idx = cpu_to_le64(offset);
 		} else {
 			BUG();
 		}

 		new_dst.k->k.p = dst_iter.pos;
 		bch2_key_resize(&new_dst.k->k,
 				min(src_k.k->p.offset - src_want.offset,
 				    dst_end.offset - dst_iter.pos.offset));

 		ret = bch2_extent_update(&trans, dst_inum, &dst_iter,
 					 new_dst.k, &disk_res,
 					 new_i_size, i_sectors_delta,
 					 true);
 		bch2_disk_reservation_put(c, &disk_res);
 	}
 	bch2_trans_iter_exit(&trans, &dst_iter);
 	bch2_trans_iter_exit(&trans, &src_iter);

 	BUG_ON(!ret && !bkey_eq(dst_iter.pos, dst_end));
 	BUG_ON(bkey_gt(dst_iter.pos, dst_end));

 	dst_done = dst_iter.pos.offset - dst_start.offset;
 	new_i_size = min(dst_iter.pos.offset << 9, new_i_size);

 	do {
 		struct bch_inode_unpacked inode_u;
 		struct btree_iter inode_iter = { NULL };

 		bch2_trans_begin(&trans);

 		ret2 = bch2_inode_peek(&trans, &inode_iter, &inode_u,
 				       dst_inum, BTREE_ITER_INTENT);

 		if (!ret2 &&
 		    inode_u.bi_size < new_i_size) {
 			inode_u.bi_size = new_i_size;
 			ret2  = bch2_inode_write(&trans, &inode_iter, &inode_u) ?:
 				bch2_trans_commit(&trans, NULL, NULL,
 						  BTREE_INSERT_NOFAIL);
 		}

 		bch2_trans_iter_exit(&trans, &inode_iter);
 	} while (bch2_err_matches(ret2, BCH_ERR_transaction_restart));

 	bch2_trans_exit(&trans);
 	bch2_bkey_buf_exit(&new_src, c);
 	bch2_bkey_buf_exit(&new_dst, c);

 	bch2_write_ref_put(c, BCH_WRITE_REF_reflink);

 	return dst_done ?: ret ?: ret2;
 }
	// SPDX-License-Identifier: GPL-2.0
	#include "bcachefs.h"
	#include "bkey_buf.h"
	#include "btree_update.h"
	#include "buckets.h"
	#include "extents.h"
	#include "inode.h"
	#include "io_misc.h"
	#include "io_write.h"
	#include "reflink.h"
	#include "subvolume.h"
	#include "super-io.h"

	#include <linux/sched/signal.h>

	static inline unsigned bkey_type_to_indirect(const struct bkey *k)
	{
	switch (k->type) {
	case KEY_TYPE_extent:
	return KEY_TYPE_reflink_v;
	case KEY_TYPE_inline_data:
	return KEY_TYPE_indirect_inline_data;
	default:
	return 0;
	}
	}

	/* reflink pointers */

	int bch2_reflink_p_invalid(const struct bch_fs *c, struct bkey_s_c k,
	enum bkey_invalid_flags flags,
	struct printbuf *err)
	{
	struct bkey_s_c_reflink_p p = bkey_s_c_to_reflink_p(k);

	if (c->sb.version >= bcachefs_metadata_version_reflink_p_fix &&
	le64_to_cpu(p.v->idx) < le32_to_cpu(p.v->front_pad)) {
	prt_printf(err, "idx < front_pad (%llu < %u)",
	le64_to_cpu(p.v->idx), le32_to_cpu(p.v->front_pad));
	return -EINVAL;
	}

	return 0;
	}

	void bch2_reflink_p_to_text(struct printbuf out, struct bch_fs c,
	struct bkey_s_c k)
	{
	struct bkey_s_c_reflink_p p = bkey_s_c_to_reflink_p(k);

	prt_printf(out, "idx %llu front_pad %u back_pad %u",
	le64_to_cpu(p.v->idx),
	le32_to_cpu(p.v->front_pad),
	le32_to_cpu(p.v->back_pad));
	}

	bool bch2_reflink_p_merge(struct bch_fs *c, struct bkey_s _l, struct bkey_s_c _r)
	{
	struct bkey_s_reflink_p l = bkey_s_to_reflink_p(_l);
	struct bkey_s_c_reflink_p r = bkey_s_c_to_reflink_p(_r);

	/*
	* Disabled for now, the triggers code needs to be reworked for merging
	* of reflink pointers to work:
	*/
	return false;

	if (le64_to_cpu(l.v->idx) + l.k->size != le64_to_cpu(r.v->idx))
	return false;

	bch2_key_resize(l.k, l.k->size + r.k->size);
	return true;
	}

	/* indirect extents */

	int bch2_reflink_v_invalid(const struct bch_fs *c, struct bkey_s_c k,
	enum bkey_invalid_flags flags,
	struct printbuf *err)
	{
	return bch2_bkey_ptrs_invalid(c, k, flags, err);
	}

	void bch2_reflink_v_to_text(struct printbuf out, struct bch_fs c,
	struct bkey_s_c k)
	{
	struct bkey_s_c_reflink_v r = bkey_s_c_to_reflink_v(k);

	prt_printf(out, "refcount: %llu ", le64_to_cpu(r.v->refcount));

	bch2_bkey_ptrs_to_text(out, c, k);
	}

	bool bch2_reflink_v_merge(struct bch_fs *c, struct bkey_s _l, struct bkey_s_c _r)
	{
	struct bkey_s_reflink_v l = bkey_s_to_reflink_v(_l);
	struct bkey_s_c_reflink_v r = bkey_s_c_to_reflink_v(_r);

	return l.v->refcount == r.v->refcount && bch2_extent_merge(c, _l, _r);
	}

	int bch2_trans_mark_reflink_v(struct btree_trans *trans,
	enum btree_id btree_id, unsigned level,
	struct bkey_s_c old, struct bkey_i *new,
	unsigned flags)
	{
	if (!(flags & BTREE_TRIGGER_OVERWRITE)) {
	struct bkey_i_reflink_v *r = bkey_i_to_reflink_v(new);

	if (!r->v.refcount) {
	r->k.type = KEY_TYPE_deleted;
	r->k.size = 0;
	set_bkey_val_u64s(&r->k, 0);
	return 0;
	}
	}

	return bch2_trans_mark_extent(trans, btree_id, level, old, new, flags);
	}

	/* indirect inline data */

	int bch2_indirect_inline_data_invalid(const struct bch_fs *c, struct bkey_s_c k,
	enum bkey_invalid_flags flags,
	struct printbuf *err)
	{
	return 0;
	}

	void bch2_indirect_inline_data_to_text(struct printbuf *out,
	struct bch_fs *c, struct bkey_s_c k)
	{
	struct bkey_s_c_indirect_inline_data d = bkey_s_c_to_indirect_inline_data(k);
	unsigned datalen = bkey_inline_data_bytes(k.k);

	prt_printf(out, "refcount %llu datalen %u: %*phN",
	le64_to_cpu(d.v->refcount), datalen,
	min(datalen, 32U), d.v->data);
	}

	int bch2_trans_mark_indirect_inline_data(struct btree_trans *trans,
	enum btree_id btree_id, unsigned level,
	struct bkey_s_c old, struct bkey_i *new,
	unsigned flags)
	{
	if (!(flags & BTREE_TRIGGER_OVERWRITE)) {
	struct bkey_i_indirect_inline_data *r =
	bkey_i_to_indirect_inline_data(new);

	if (!r->v.refcount) {
	r->k.type = KEY_TYPE_deleted;
	r->k.size = 0;
	set_bkey_val_u64s(&r->k, 0);
	}
	}

	return 0;
	}

	static int bch2_make_extent_indirect(struct btree_trans *trans,
	struct btree_iter *extent_iter,
	struct bkey_i *orig)
	{
	struct bch_fs *c = trans->c;
	struct btree_iter reflink_iter = { NULL };
	struct bkey_s_c k;
	struct bkey_i *r_v;
	struct bkey_i_reflink_p *r_p;
	__le64 *refcount;
	int ret;

	if (orig->k.type == KEY_TYPE_inline_data)
	bch2_check_set_feature(c, BCH_FEATURE_reflink_inline_data);

	bch2_trans_iter_init(trans, &reflink_iter, BTREE_ID_reflink, POS_MAX,
	BTREE_ITER_INTENT);
	k = bch2_btree_iter_peek_prev(&reflink_iter);
	ret = bkey_err(k);
	if (ret)
	goto err;

	r_v = bch2_trans_kmalloc(trans, sizeof(__le64) + bkey_bytes(&orig->k));
	ret = PTR_ERR_OR_ZERO(r_v);
	if (ret)
	goto err;

	bkey_init(&r_v->k);
	r_v->k.type = bkey_type_to_indirect(&orig->k);
	r_v->k.p = reflink_iter.pos;
	bch2_key_resize(&r_v->k, orig->k.size);
	r_v->k.version = orig->k.version;

	set_bkey_val_bytes(&r_v->k, sizeof(__le64) + bkey_val_bytes(&orig->k));

	refcount = bkey_refcount(r_v);
	*refcount = 0;
	memcpy(refcount + 1, &orig->v, bkey_val_bytes(&orig->k));

	ret = bch2_trans_update(trans, &reflink_iter, r_v, 0);
	if (ret)
	goto err;

	/*
	* orig is in a bkey_buf which statically allocates 5 64s for the val,
	* so we know it will be big enough:
	*/
	orig->k.type = KEY_TYPE_reflink_p;
	r_p = bkey_i_to_reflink_p(orig);
	set_bkey_val_bytes(&r_p->k, sizeof(r_p->v));

	/* FORTIFY_SOURCE is broken here, and doesn't provide unsafe_memset() */
	#if !defined(__NO_FORTIFY) && defined(__OPTIMIZE__) && defined(CONFIG_FORTIFY_SOURCE)
	__underlying_memset(&r_p->v, 0, sizeof(r_p->v));
	#else
	memset(&r_p->v, 0, sizeof(r_p->v));
	#endif

	r_p->v.idx = cpu_to_le64(bkey_start_offset(&r_v->k));

	ret = bch2_trans_update(trans, extent_iter, &r_p->k_i,
	BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
	err:
	bch2_trans_iter_exit(trans, &reflink_iter);

	return ret;
	}

	static struct bkey_s_c get_next_src(struct btree_iter *iter, struct bpos end)
	{
	struct bkey_s_c k;
	int ret;

	for_each_btree_key_upto_continue_norestart(*iter, end, 0, k, ret) {
	if (bkey_extent_is_unwritten(k))
	continue;

	if (bkey_extent_is_data(k.k))
	return k;
	}

	if (bkey_ge(iter->pos, end))
	bch2_btree_iter_set_pos(iter, end);
	return ret ? bkey_s_c_err(ret) : bkey_s_c_null;
	}

	s64 bch2_remap_range(struct bch_fs *c,
	subvol_inum dst_inum, u64 dst_offset,
	subvol_inum src_inum, u64 src_offset,
	u64 remap_sectors,
	u64 new_i_size, s64 *i_sectors_delta)
	{
	struct btree_trans trans;
	struct btree_iter dst_iter, src_iter;
	struct bkey_s_c src_k;
	struct bkey_buf new_dst, new_src;
	struct bpos dst_start = POS(dst_inum.inum, dst_offset);
	struct bpos src_start = POS(src_inum.inum, src_offset);
	struct bpos dst_end = dst_start, src_end = src_start;
	struct bpos src_want;
	u64 dst_done;
	u32 dst_snapshot, src_snapshot;
	int ret = 0, ret2 = 0;

	if (!bch2_write_ref_tryget(c, BCH_WRITE_REF_reflink))
	return -BCH_ERR_erofs_no_writes;

	bch2_check_set_feature(c, BCH_FEATURE_reflink);

	dst_end.offset += remap_sectors;
	src_end.offset += remap_sectors;

	bch2_bkey_buf_init(&new_dst);
	bch2_bkey_buf_init(&new_src);
	bch2_trans_init(&trans, c, BTREE_ITER_MAX, 4096);

	bch2_trans_iter_init(&trans, &src_iter, BTREE_ID_extents, src_start,
	BTREE_ITER_INTENT);
	bch2_trans_iter_init(&trans, &dst_iter, BTREE_ID_extents, dst_start,
	BTREE_ITER_INTENT);

	while ((ret == 0 \|\|
	bch2_err_matches(ret, BCH_ERR_transaction_restart)) &&
	bkey_lt(dst_iter.pos, dst_end)) {
	struct disk_reservation disk_res = { 0 };

	bch2_trans_begin(&trans);

	if (fatal_signal_pending(current)) {
	ret = -EINTR;
	break;
	}

	ret = bch2_subvolume_get_snapshot(&trans, src_inum.subvol,
	&src_snapshot);
	if (ret)
	continue;

	bch2_btree_iter_set_snapshot(&src_iter, src_snapshot);

	ret = bch2_subvolume_get_snapshot(&trans, dst_inum.subvol,
	&dst_snapshot);
	if (ret)
	continue;

	bch2_btree_iter_set_snapshot(&dst_iter, dst_snapshot);

	dst_done = dst_iter.pos.offset - dst_start.offset;
	src_want = POS(src_start.inode, src_start.offset + dst_done);
	bch2_btree_iter_set_pos(&src_iter, src_want);

	src_k = get_next_src(&src_iter, src_end);
	ret = bkey_err(src_k);
	if (ret)
	continue;

	if (bkey_lt(src_want, src_iter.pos)) {
	ret = bch2_fpunch_at(&trans, &dst_iter, dst_inum,
	min(dst_end.offset,
	dst_iter.pos.offset +
	src_iter.pos.offset - src_want.offset),
	i_sectors_delta);
	continue;
	}

	if (src_k.k->type != KEY_TYPE_reflink_p) {
	bch2_btree_iter_set_pos_to_extent_start(&src_iter);

	bch2_bkey_buf_reassemble(&new_src, c, src_k);
	src_k = bkey_i_to_s_c(new_src.k);

	ret = bch2_make_extent_indirect(&trans, &src_iter,
	new_src.k);
	if (ret)
	continue;

	BUG_ON(src_k.k->type != KEY_TYPE_reflink_p);
	}

	if (src_k.k->type == KEY_TYPE_reflink_p) {
	struct bkey_s_c_reflink_p src_p =
	bkey_s_c_to_reflink_p(src_k);
	struct bkey_i_reflink_p *dst_p =
	bkey_reflink_p_init(new_dst.k);

	u64 offset = le64_to_cpu(src_p.v->idx) +
	(src_want.offset -
	bkey_start_offset(src_k.k));

	dst_p->v.idx = cpu_to_le64(offset);
	} else {
	BUG();
	}

	new_dst.k->k.p = dst_iter.pos;
	bch2_key_resize(&new_dst.k->k,
	min(src_k.k->p.offset - src_want.offset,
	dst_end.offset - dst_iter.pos.offset));

	ret = bch2_extent_update(&trans, dst_inum, &dst_iter,
	new_dst.k, &disk_res,
	new_i_size, i_sectors_delta,
	true);
	bch2_disk_reservation_put(c, &disk_res);
	}
	bch2_trans_iter_exit(&trans, &dst_iter);
	bch2_trans_iter_exit(&trans, &src_iter);

	BUG_ON(!ret && !bkey_eq(dst_iter.pos, dst_end));
	BUG_ON(bkey_gt(dst_iter.pos, dst_end));

	dst_done = dst_iter.pos.offset - dst_start.offset;
	new_i_size = min(dst_iter.pos.offset << 9, new_i_size);

	do {
	struct bch_inode_unpacked inode_u;
	struct btree_iter inode_iter = { NULL };

	bch2_trans_begin(&trans);

	ret2 = bch2_inode_peek(&trans, &inode_iter, &inode_u,
	dst_inum, BTREE_ITER_INTENT);

	if (!ret2 &&
	inode_u.bi_size < new_i_size) {
	inode_u.bi_size = new_i_size;
	ret2 = bch2_inode_write(&trans, &inode_iter, &inode_u) ?:
	bch2_trans_commit(&trans, NULL, NULL,
	BTREE_INSERT_NOFAIL);
	}

	bch2_trans_iter_exit(&trans, &inode_iter);
	} while (bch2_err_matches(ret2, BCH_ERR_transaction_restart));

	bch2_trans_exit(&trans);
	bch2_bkey_buf_exit(&new_src, c);
	bch2_bkey_buf_exit(&new_dst, c);

	bch2_write_ref_put(c, BCH_WRITE_REF_reflink);

	return dst_done ?: ret ?: ret2;
	}