bcachefs: bch2_inode_peek()/bch2_inode_write()

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

5 files changed, 198 insertions, 192 deletions

diff --git a/fs/bcachefs/acl.c b/fs/bcachefs/acl.c
index 5a4263806610..4e631e04cf0c 100644
--- a/fs/bcachefs/acl.c
+++ b/fs/bcachefs/acl.c
@@ -281,51 +281,54 @@ int bch2_set_acl_trans(struct btree_trans *trans,
 	return ret == -ENOENT ? 0 : ret;
 }
 
-static int inode_update_for_set_acl_fn(struct bch_inode_info *inode,
-				       struct bch_inode_unpacked *bi,
-				       void *p)
-{
-	struct bch_fs *c = inode->v.i_sb->s_fs_info;
-	umode_t mode = (unsigned long) p;
-
-	bi->bi_ctime	= bch2_current_time(c);
-	bi->bi_mode	= mode;
-	return 0;
-}
-
 int bch2_set_acl(struct mnt_idmap *idmap,
 		 struct dentry *dentry,
-		 struct posix_acl *acl, int type)
+		 struct posix_acl *_acl, int type)
 {
 	struct bch_inode_info *inode = to_bch_ei(dentry->d_inode);
 	struct bch_fs *c = inode->v.i_sb->s_fs_info;
 	struct btree_trans trans;
+	struct btree_iter *inode_iter;
 	struct bch_inode_unpacked inode_u;
-	umode_t mode = inode->v.i_mode;
+	struct posix_acl *acl;
+	umode_t mode;
 	int ret;
 
 	mutex_lock(&inode->ei_update_lock);
 	bch2_trans_init(&trans, c, 0, 0);
+retry:
+	bch2_trans_begin(&trans);
+	acl = _acl;
 
-	if (type == ACL_TYPE_ACCESS && acl) {
+	inode_iter = bch2_inode_peek(&trans, &inode_u, inode->v.i_ino,
+				     BTREE_ITER_INTENT);
+	ret = PTR_ERR_OR_ZERO(inode_iter);
+	if (ret)
+		goto btree_err;
+
+	mode = inode_u.bi_mode;
+
+	if (type == ACL_TYPE_ACCESS) {
 		ret = posix_acl_update_mode(idmap, &inode->v, &mode, &acl);
 		if (ret)
 			goto err;
 	}
-retry:
-	bch2_trans_begin(&trans);
 
-	ret   = bch2_set_acl_trans(&trans,
-				   &inode->ei_inode,
-				   &inode->ei_str_hash,
-				   acl, type) ?:
-		bch2_write_inode_trans(&trans, inode, &inode_u,
-				       inode_update_for_set_acl_fn,
-				       (void *)(unsigned long) mode) ?:
+	ret = bch2_set_acl_trans(&trans, &inode_u,
+				 &inode->ei_str_hash,
+				 acl, type);
+	if (ret)
+		goto btree_err;
+
+	inode_u.bi_ctime	= bch2_current_time(c);
+	inode_u.bi_mode		= mode;
+
+	ret =   bch2_inode_write(&trans, inode_iter, &inode_u) ?:
 		bch2_trans_commit(&trans, NULL,
 				  &inode->ei_journal_seq,
 				  BTREE_INSERT_ATOMIC|
 				  BTREE_INSERT_NOUNLOCK);
+btree_err:
 	if (ret == -EINTR)
 		goto retry;
 	if (unlikely(ret))
diff --git a/fs/bcachefs/fs-io.c b/fs/bcachefs/fs-io.c
index be121b755fc7..49c0343da462 100644
--- a/fs/bcachefs/fs-io.c
+++ b/fs/bcachefs/fs-io.c
@@ -241,11 +241,13 @@ static void i_sectors_acct(struct bch_fs *c, struct bch_inode_info *inode,
 
 static int sum_sector_overwrites(struct btree_trans *trans,
 				 struct btree_iter *extent_iter,
-				 struct bkey_i *new, bool *allocating,
+				 struct bkey_i *new,
+				 bool may_allocate,
 				 s64 *delta)
 {
 	struct btree_iter *iter;
 	struct bkey_s_c old;
+	int ret = 0;
 
 	*delta = 0;
 
@@ -253,21 +255,13 @@ static int sum_sector_overwrites(struct btree_trans *trans,
 	if (IS_ERR(iter))
 		return PTR_ERR(iter);
 
-	old = bch2_btree_iter_peek_slot(iter);
-
-	while (1) {
-		/*
-		 * should not be possible to get an error here, since we're
-		 * carefully not advancing past @new and thus whatever leaf node
-		 * @_iter currently points to:
-		 */
-		BUG_ON(bkey_err(old));
-
-		if (allocating &&
-		    !*allocating &&
+	for_each_btree_key_continue(iter, BTREE_ITER_SLOTS, old, ret) {
+		if (!may_allocate &&
 		    bch2_bkey_nr_ptrs_allocated(old) <
-		    bch2_bkey_nr_dirty_ptrs(bkey_i_to_s_c(new)))
-			*allocating = true;
+		    bch2_bkey_nr_dirty_ptrs(bkey_i_to_s_c(new))) {
+			ret = -ENOSPC;
+			break;
+		}
 
 		*delta += (min(new->k.p.offset,
 			      old.k->p.offset) -
@@ -278,12 +272,10 @@ static int sum_sector_overwrites(struct btree_trans *trans,
 
 		if (bkey_cmp(old.k->p, new->k.p) >= 0)
 			break;
-
-		old = bch2_btree_iter_next_slot(iter);
 	}
 
 	bch2_trans_iter_put(trans, iter);
-	return 0;
+	return ret;
 }
 
 int bch2_extent_update(struct btree_trans *trans,
@@ -301,9 +293,7 @@ int bch2_extent_update(struct btree_trans *trans,
 	struct btree_iter *inode_iter = NULL;
 	struct bch_inode_unpacked inode_u;
 	struct bkey_inode_buf inode_p;
-	bool allocating = false;
 	bool extended = false;
-	bool inode_locked = false;
 	s64 i_sectors_delta;
 	int ret;
 
@@ -315,15 +305,11 @@ int bch2_extent_update(struct btree_trans *trans,
 	if (ret)
 		return ret;
 
-	ret = sum_sector_overwrites(trans, extent_iter,
-				    k, &allocating,
-				    &i_sectors_delta);
+	ret = sum_sector_overwrites(trans, extent_iter, k,
+				    may_allocate, &i_sectors_delta);
 	if (ret)
 		return ret;
 
-	if (!may_allocate && allocating)
-		return -ENOSPC;
-
 	bch2_trans_update(trans, extent_iter, k);
 
 	new_i_size = min(k->k.p.offset << 9, new_i_size);
@@ -331,29 +317,28 @@ int bch2_extent_update(struct btree_trans *trans,
 	/* XXX: inode->i_size locking */
 	if (i_sectors_delta ||
 	    new_i_size > inode->ei_inode.bi_size) {
-		inode_iter = bch2_trans_get_iter(trans,
-			BTREE_ID_INODES,
-			POS(k->k.p.inode, 0),
-			BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
+		inode_iter = bch2_inode_peek(trans, &inode_u,
+				k->k.p.inode, BTREE_ITER_INTENT);
 		if (IS_ERR(inode_iter))
 			return PTR_ERR(inode_iter);
 
-		ret = bch2_btree_iter_traverse(inode_iter);
-		if (ret)
-			goto err;
-
-		inode_u = inode->ei_inode;
 		inode_u.bi_sectors += i_sectors_delta;
 
-		/* XXX: this is slightly suspect */
+		/*
+		 * XXX: can BCH_INODE_I_SIZE_DIRTY be true here? i.e. can we
+		 * race with truncate?
+		 */
 		if (!(inode_u.bi_flags & BCH_INODE_I_SIZE_DIRTY) &&
 		    new_i_size > inode_u.bi_size) {
 			inode_u.bi_size = new_i_size;
 			extended = true;
 		}
 
-		bch2_inode_pack(&inode_p, &inode_u);
-		bch2_trans_update(trans, inode_iter, &inode_p.inode.k_i);
+		if (i_sectors_delta || extended) {
+			bch2_inode_pack(&inode_p, &inode_u);
+			bch2_trans_update(trans, inode_iter,
+					  &inode_p.inode.k_i);
+		}
 	}
 
 	ret = bch2_trans_commit(trans, disk_res,
@@ -365,33 +350,25 @@ int bch2_extent_update(struct btree_trans *trans,
 	if (ret)
 		goto err;
 
-	inode->ei_inode.bi_sectors += i_sectors_delta;
-
-	EBUG_ON(i_sectors_delta &&
-		inode->ei_inode.bi_sectors != inode_u.bi_sectors);
-
-	if (extended) {
-		inode->ei_inode.bi_size = new_i_size;
-
-		if (direct) {
-			spin_lock(&inode->v.i_lock);
-			if (new_i_size > inode->v.i_size)
-				i_size_write(&inode->v, new_i_size);
-			spin_unlock(&inode->v.i_lock);
-		}
+	if (i_sectors_delta || extended) {
+		inode->ei_inode.bi_sectors	= inode_u.bi_sectors;
+		inode->ei_inode.bi_size		= inode_u.bi_size;
 	}
 
 	if (direct)
 		i_sectors_acct(c, inode, quota_res, i_sectors_delta);
+	if (direct && extended) {
+		spin_lock(&inode->v.i_lock);
+		if (new_i_size > inode->v.i_size)
+			i_size_write(&inode->v, new_i_size);
+		spin_unlock(&inode->v.i_lock);
+	}
 
 	if (total_delta)
 		*total_delta += i_sectors_delta;
 err:
 	if (!IS_ERR_OR_NULL(inode_iter))
 		bch2_trans_iter_put(trans, inode_iter);
-	if (inode_locked)
-		mutex_unlock(&inode->ei_update_lock);
-
 	return ret;
 }
 
diff --git a/fs/bcachefs/fs.c b/fs/bcachefs/fs.c
index 0a83d5f61a6b..cbe1b90e80c2 100644
--- a/fs/bcachefs/fs.c
+++ b/fs/bcachefs/fs.c
@@ -155,41 +155,19 @@ int __must_check bch2_write_inode_trans(struct btree_trans *trans,
 				void *p)
 {
 	struct btree_iter *iter = NULL;
-	struct bkey_inode_buf *inode_p;
-	struct bkey_s_c k;
 	int ret = 0;
 
-	iter = bch2_trans_get_iter(trans, BTREE_ID_INODES,
-				   POS(inode->v.i_ino, 0),
-				   BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
-	if (IS_ERR(iter))
-		return PTR_ERR(iter);
-
-	k = bch2_btree_iter_peek_slot(iter);
-	ret = bkey_err(k);
+	iter = bch2_inode_peek(trans, inode_u, inode->v.i_ino,
+			       BTREE_ITER_INTENT);
+	ret = PTR_ERR_OR_ZERO(iter);
 	if (ret)
 		return ret;
 
-	if (k.k->type != KEY_TYPE_inode)
-		return -EIO;
-
-	ret = bch2_inode_unpack(bkey_s_c_to_inode(k), inode_u);
+	ret = set ? set(inode, inode_u, p) : 0;
 	if (ret)
 		return ret;
 
-	if (set) {
-		ret = set(inode, inode_u, p);
-		if (ret)
-			return ret;
-	}
-
-	inode_p = bch2_trans_kmalloc(trans, sizeof(*inode_p));
-	if (IS_ERR(inode_p))
-		return PTR_ERR(inode_p);
-
-	bch2_inode_pack(inode_p, inode_u);
-	bch2_trans_update(trans, iter, &inode_p->inode.k_i);
-	return 0;
+	return bch2_inode_write(trans, iter, inode_u);
 }
 
 int __must_check bch2_write_inode(struct bch_fs *c,
@@ -531,23 +509,13 @@ static int bch2_create(struct mnt_idmap *idmap,
 	return 0;
 }
 
-static int inode_update_for_link_fn(struct bch_inode_info *inode,
-				    struct bch_inode_unpacked *bi,
-				    void *p)
-{
-	struct bch_fs *c = inode->v.i_sb->s_fs_info;
-
-	bi->bi_ctime = bch2_current_time(c);
-	bch2_inode_nlink_inc(bi);
-	return 0;
-}
-
 static int __bch2_link(struct bch_fs *c,
 		       struct bch_inode_info *inode,
 		       struct bch_inode_info *dir,
 		       struct dentry *dentry)
 {
 	struct btree_trans trans;
+	struct btree_iter *inode_iter;
 	struct bch_inode_unpacked inode_u;
 	int ret;
 
@@ -555,21 +523,30 @@ static int __bch2_link(struct bch_fs *c,
 	bch2_trans_init(&trans, c, 4, 1024);
 retry:
 	bch2_trans_begin(&trans);
-
 	ret   = __bch2_dirent_create(&trans, dir->v.i_ino,
 				     &dir->ei_str_hash,
 				     mode_to_type(inode->v.i_mode),
 				     &dentry->d_name,
 				     inode->v.i_ino,
-				     BCH_HASH_SET_MUST_CREATE) ?:
-		bch2_write_inode_trans(&trans, inode, &inode_u,
-				       inode_update_for_link_fn,
-				       NULL) ?:
-		bch2_trans_commit(&trans, NULL,
-				  &inode->ei_journal_seq,
-				  BTREE_INSERT_ATOMIC|
-				  BTREE_INSERT_NOUNLOCK);
+				     BCH_HASH_SET_MUST_CREATE);
+	if (ret)
+		goto err;
+
+	inode_iter = bch2_inode_peek(&trans, &inode_u, inode->v.i_ino,
+				     BTREE_ITER_INTENT);
+	ret = PTR_ERR_OR_ZERO(inode_iter);
+	if (ret)
+		goto err;
+
+	inode_u.bi_ctime = bch2_current_time(c);
+	bch2_inode_nlink_inc(&inode_u);
 
+	ret =   bch2_inode_write(&trans, inode_iter, &inode_u) ?:
+		bch2_trans_commit(&trans, NULL,
+				&inode->ei_journal_seq,
+				BTREE_INSERT_ATOMIC|
+				BTREE_INSERT_NOUNLOCK);
+err:
 	if (ret == -EINTR)
 		goto retry;
 
@@ -600,36 +577,12 @@ static int bch2_link(struct dentry *old_dentry, struct inode *vdir,
 	return 0;
 }
 
-static int inode_update_dir_for_unlink_fn(struct bch_inode_info *inode,
-					  struct bch_inode_unpacked *bi,
-					  void *p)
-{
-	struct bch_fs *c = inode->v.i_sb->s_fs_info;
-	struct bch_inode_info *unlink_inode = p;
-
-	bi->bi_mtime = bi->bi_ctime = bch2_current_time(c);
-
-	bi->bi_nlink -= S_ISDIR(unlink_inode->v.i_mode);
-
-	return 0;
-}
-
-static int inode_update_for_unlink_fn(struct bch_inode_info *inode,
-				      struct bch_inode_unpacked *bi,
-				      void *p)
-{
-	struct bch_fs *c = inode->v.i_sb->s_fs_info;
-
-	bi->bi_ctime = bch2_current_time(c);
-	bch2_inode_nlink_dec(bi);
-	return 0;
-}
-
 static int bch2_unlink(struct inode *vdir, struct dentry *dentry)
 {
 	struct bch_fs *c = vdir->i_sb->s_fs_info;
 	struct bch_inode_info *dir = to_bch_ei(vdir);
 	struct bch_inode_info *inode = to_bch_ei(dentry->d_inode);
+	struct btree_iter *dir_iter, *inode_iter;
 	struct bch_inode_unpacked dir_u, inode_u;
 	struct btree_trans trans;
 	int ret;
@@ -641,25 +594,42 @@ retry:
 
 	ret   = __bch2_dirent_delete(&trans, dir->v.i_ino,
 				     &dir->ei_str_hash,
-				     &dentry->d_name) ?:
-		bch2_write_inode_trans(&trans, dir, &dir_u,
-				       inode_update_dir_for_unlink_fn,
-				       inode) ?:
-		bch2_write_inode_trans(&trans, inode, &inode_u,
-				       inode_update_for_unlink_fn,
-				       NULL) ?:
+				     &dentry->d_name);
+	if (ret)
+		goto btree_err;
+
+	dir_iter = bch2_inode_peek(&trans, &dir_u, dir->v.i_ino,
+				   BTREE_ITER_INTENT);
+	ret = PTR_ERR_OR_ZERO(dir_iter);
+	if (ret)
+		goto btree_err;
+
+	inode_iter = bch2_inode_peek(&trans, &inode_u, inode->v.i_ino,
+				     BTREE_ITER_INTENT);
+	ret = PTR_ERR_OR_ZERO(inode_iter);
+	if (ret)
+		goto btree_err;
+
+	dir_u.bi_mtime = dir_u.bi_ctime = inode_u.bi_ctime =
+		bch2_current_time(c);
+
+	dir_u.bi_nlink -= S_ISDIR(inode_u.bi_mode);
+	bch2_inode_nlink_dec(&inode_u);
+
+	ret =   bch2_inode_write(&trans, dir_iter, &dir_u) ?:
+		bch2_inode_write(&trans, inode_iter, &inode_u) ?:
 		bch2_trans_commit(&trans, NULL,
 				  &dir->ei_journal_seq,
 				  BTREE_INSERT_ATOMIC|
 				  BTREE_INSERT_NOUNLOCK|
 				  BTREE_INSERT_NOFAIL);
+btree_err:
 	if (ret == -EINTR)
 		goto retry;
 	if (ret)
 		goto err;
 
-	if (dir->ei_journal_seq > inode->ei_journal_seq)
-		inode->ei_journal_seq = dir->ei_journal_seq;
+	journal_seq_copy(inode, dir->ei_journal_seq);
 
 	bch2_inode_update_after_write(c, dir, &dir_u,
 				      ATTR_MTIME|ATTR_CTIME);
@@ -953,67 +923,60 @@ err:
 	return ret;
 }
 
-struct inode_write_setattr {
-	struct iattr		*attr;
-	struct mnt_idmap	*idmap;
-};
-
-static int inode_update_for_setattr_fn(struct bch_inode_info *inode,
-				       struct bch_inode_unpacked *bi,
-				       void *p)
+static void bch2_setattr_copy(struct mnt_idmap *idmap,
+			      struct bch_inode_info *inode,
+			      struct bch_inode_unpacked *bi,
+			      struct iattr *attr)
 {
 	struct bch_fs *c = inode->v.i_sb->s_fs_info;
-	struct inode_write_setattr *s = p;
-	unsigned int ia_valid = s->attr->ia_valid;
+	unsigned int ia_valid = attr->ia_valid;
 
 	if (ia_valid & ATTR_UID)
-		bi->bi_uid = from_kuid(i_user_ns(&inode->v), s->attr->ia_uid);
+		bi->bi_uid = from_kuid(i_user_ns(&inode->v), attr->ia_uid);
 	if (ia_valid & ATTR_GID)
-		bi->bi_gid = from_kgid(i_user_ns(&inode->v), s->attr->ia_gid);
+		bi->bi_gid = from_kgid(i_user_ns(&inode->v), attr->ia_gid);
 
 	if (ia_valid & ATTR_ATIME)
-		bi->bi_atime = timespec_to_bch2_time(c, s->attr->ia_atime);
+		bi->bi_atime = timespec_to_bch2_time(c, attr->ia_atime);
 	if (ia_valid & ATTR_MTIME)
-		bi->bi_mtime = timespec_to_bch2_time(c, s->attr->ia_mtime);
+		bi->bi_mtime = timespec_to_bch2_time(c, attr->ia_mtime);
 	if (ia_valid & ATTR_CTIME)
-		bi->bi_ctime = timespec_to_bch2_time(c, s->attr->ia_ctime);
+		bi->bi_ctime = timespec_to_bch2_time(c, attr->ia_ctime);
 
 	if (ia_valid & ATTR_MODE) {
-		umode_t mode = s->attr->ia_mode;
+		umode_t mode = attr->ia_mode;
 		kgid_t gid = ia_valid & ATTR_GID
-			? s->attr->ia_gid
+			? attr->ia_gid
 			: inode->v.i_gid;
 
 		if (!in_group_p(gid) &&
-		    !capable_wrt_inode_uidgid(s->idmap, &inode->v, CAP_FSETID))
+		    !capable_wrt_inode_uidgid(idmap, &inode->v, CAP_FSETID))
 			mode &= ~S_ISGID;
 		bi->bi_mode = mode;
 	}
-
-	return 0;
 }
 
 static int bch2_setattr_nonsize(struct mnt_idmap *idmap,
 				struct bch_inode_info *inode,
-				struct iattr *iattr)
+				struct iattr *attr)
 {
 	struct bch_fs *c = inode->v.i_sb->s_fs_info;
 	struct bch_qid qid;
 	struct btree_trans trans;
+	struct btree_iter *inode_iter;
 	struct bch_inode_unpacked inode_u;
 	struct posix_acl *acl = NULL;
-	struct inode_write_setattr s = { iattr, idmap };
 	int ret;
 
 	mutex_lock(&inode->ei_update_lock);
 
 	qid = inode->ei_qid;
 
-	if (iattr->ia_valid & ATTR_UID)
-		qid.q[QTYP_USR] = from_kuid(i_user_ns(&inode->v), iattr->ia_uid);
+	if (attr->ia_valid & ATTR_UID)
+		qid.q[QTYP_USR] = from_kuid(i_user_ns(&inode->v), attr->ia_uid);
 
-	if (iattr->ia_valid & ATTR_GID)
-		qid.q[QTYP_GRP] = from_kgid(i_user_ns(&inode->v), iattr->ia_gid);
+	if (attr->ia_valid & ATTR_GID)
+		qid.q[QTYP_GRP] = from_kgid(i_user_ns(&inode->v), attr->ia_gid);
 
 	ret = bch2_fs_quota_transfer(c, inode, qid, ~0,
 				     KEY_TYPE_QUOTA_PREALLOC);
@@ -1026,22 +989,33 @@ retry:
 	kfree(acl);
 	acl = NULL;
 
-	ret = bch2_write_inode_trans(&trans, inode, &inode_u,
-				inode_update_for_setattr_fn, &s) ?:
-		(iattr->ia_valid & ATTR_MODE
-		 ? bch2_acl_chmod(&trans, inode, iattr->ia_mode, &acl)
-		 : 0) ?:
+	inode_iter = bch2_inode_peek(&trans, &inode_u, inode->v.i_ino,
+				     BTREE_ITER_INTENT);
+	ret = PTR_ERR_OR_ZERO(inode_iter);
+	if (ret)
+		goto btree_err;
+
+	bch2_setattr_copy(idmap, inode, &inode_u, attr);
+
+	if (attr->ia_valid & ATTR_MODE) {
+		ret = bch2_acl_chmod(&trans, inode, inode_u.bi_mode, &acl);
+		if (ret)
+			goto btree_err;
+	}
+
+	ret =   bch2_inode_write(&trans, inode_iter, &inode_u) ?:
 		bch2_trans_commit(&trans, NULL,
 				  &inode->ei_journal_seq,
 				  BTREE_INSERT_ATOMIC|
 				  BTREE_INSERT_NOUNLOCK|
 				  BTREE_INSERT_NOFAIL);
+btree_err:
 	if (ret == -EINTR)
 		goto retry;
 	if (unlikely(ret))
 		goto err_trans;
 
-	bch2_inode_update_after_write(c, inode, &inode_u, iattr->ia_valid);
+	bch2_inode_update_after_write(c, inode, &inode_u, attr->ia_valid);
 
 	if (acl)
 		set_cached_acl(&inode->v, ACL_TYPE_ACCESS, acl);
diff --git a/fs/bcachefs/inode.c b/fs/bcachefs/inode.c
index f192536558c1..fc38cfb9e939 100644
--- a/fs/bcachefs/inode.c
+++ b/fs/bcachefs/inode.c
@@ -181,6 +181,53 @@ int bch2_inode_unpack(struct bkey_s_c_inode inode,
 	return 0;
 }
 
+struct btree_iter *bch2_inode_peek(struct btree_trans *trans,
+				   struct bch_inode_unpacked *inode,
+				   u64 inum, unsigned flags)
+{
+	struct btree_iter *iter;
+	struct bkey_s_c k;
+	int ret;
+
+	iter = bch2_trans_get_iter(trans, BTREE_ID_INODES, POS(inum, 0),
+				   BTREE_ITER_SLOTS|flags);
+	if (IS_ERR(iter))
+		return iter;
+
+	k = bch2_btree_iter_peek_slot(iter);
+	ret = bkey_err(k);
+	if (ret)
+		goto err;
+
+	ret = k.k->type == KEY_TYPE_inode ? 0 : -EIO;
+	if (ret)
+		goto err;
+
+	ret = bch2_inode_unpack(bkey_s_c_to_inode(k), inode);
+	if (ret)
+		goto err;
+
+	return iter;
+err:
+	bch2_trans_iter_put(trans, iter);
+	return ERR_PTR(ret);
+}
+
+int bch2_inode_write(struct btree_trans *trans,
+		     struct btree_iter *iter,
+		     struct bch_inode_unpacked *inode)
+{
+	struct bkey_inode_buf *inode_p;
+
+	inode_p = bch2_trans_kmalloc(trans, sizeof(*inode_p));
+	if (IS_ERR(inode_p))
+		return PTR_ERR(inode_p);
+
+	bch2_inode_pack(inode_p, inode);
+	bch2_trans_update(trans, iter, &inode_p->inode.k_i);
+	return 0;
+}
+
 const char *bch2_inode_invalid(const struct bch_fs *c, struct bkey_s_c k)
 {
 		struct bkey_s_c_inode inode = bkey_s_c_to_inode(k);
diff --git a/fs/bcachefs/inode.h b/fs/bcachefs/inode.h
index e88ec78071bd..c5626c668639 100644
--- a/fs/bcachefs/inode.h
+++ b/fs/bcachefs/inode.h
@@ -46,6 +46,11 @@ struct bkey_inode_buf {
 void bch2_inode_pack(struct bkey_inode_buf *, const struct bch_inode_unpacked *);
 int bch2_inode_unpack(struct bkey_s_c_inode, struct bch_inode_unpacked *);
 
+struct btree_iter *bch2_inode_peek(struct btree_trans *,
+			struct bch_inode_unpacked *, u64, unsigned);
+int bch2_inode_write(struct btree_trans *, struct btree_iter *,
+		     struct bch_inode_unpacked *);
+
 void bch2_inode_init(struct bch_fs *, struct bch_inode_unpacked *,
 		     uid_t, gid_t, umode_t, dev_t,
 		     struct bch_inode_unpacked *);