1 files changed, 574 insertions, 0 deletions

diff --git a/fs/bcachefs/dirent.c b/fs/bcachefs/dirent.c
new file mode 100644
index 000000000000..faffc98d5605
--- /dev/null
+++ b/fs/bcachefs/dirent.c
@@ -0,0 +1,574 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "bcachefs.h"
+#include "bkey_buf.h"
+#include "bkey_methods.h"
+#include "btree_update.h"
+#include "extents.h"
+#include "dirent.h"
+#include "fs.h"
+#include "keylist.h"
+#include "str_hash.h"
+#include "subvolume.h"
+
+#include <linux/dcache.h>
+
+static unsigned bch2_dirent_name_bytes(struct bkey_s_c_dirent d)
+{
+	if (bkey_val_bytes(d.k) < offsetof(struct bch_dirent, d_name))
+		return 0;
+
+	unsigned bkey_u64s = bkey_val_u64s(d.k);
+	unsigned bkey_bytes = bkey_u64s * sizeof(u64);
+	u64 last_u64 = ((u64*)d.v)[bkey_u64s - 1];
+#if CPU_BIG_ENDIAN
+	unsigned trailing_nuls = last_u64 ? __builtin_ctzll(last_u64) / 8 : 64 / 8;
+#else
+	unsigned trailing_nuls = last_u64 ? __builtin_clzll(last_u64) / 8 : 64 / 8;
+#endif
+
+	return bkey_bytes -
+		offsetof(struct bch_dirent, d_name) -
+		trailing_nuls;
+}
+
+struct qstr bch2_dirent_get_name(struct bkey_s_c_dirent d)
+{
+	return (struct qstr) QSTR_INIT(d.v->d_name, bch2_dirent_name_bytes(d));
+}
+
+static u64 bch2_dirent_hash(const struct bch_hash_info *info,
+			    const struct qstr *name)
+{
+	struct bch_str_hash_ctx ctx;
+
+	bch2_str_hash_init(&ctx, info);
+	bch2_str_hash_update(&ctx, info, name->name, name->len);
+
+	/* [0,2) reserved for dots */
+	return max_t(u64, bch2_str_hash_end(&ctx, info), 2);
+}
+
+static u64 dirent_hash_key(const struct bch_hash_info *info, const void *key)
+{
+	return bch2_dirent_hash(info, key);
+}
+
+static u64 dirent_hash_bkey(const struct bch_hash_info *info, struct bkey_s_c k)
+{
+	struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
+	struct qstr name = bch2_dirent_get_name(d);
+
+	return bch2_dirent_hash(info, &name);
+}
+
+static bool dirent_cmp_key(struct bkey_s_c _l, const void *_r)
+{
+	struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l);
+	const struct qstr l_name = bch2_dirent_get_name(l);
+	const struct qstr *r_name = _r;
+
+	return !qstr_eq(l_name, *r_name);
+}
+
+static bool dirent_cmp_bkey(struct bkey_s_c _l, struct bkey_s_c _r)
+{
+	struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l);
+	struct bkey_s_c_dirent r = bkey_s_c_to_dirent(_r);
+	const struct qstr l_name = bch2_dirent_get_name(l);
+	const struct qstr r_name = bch2_dirent_get_name(r);
+
+	return !qstr_eq(l_name, r_name);
+}
+
+static bool dirent_is_visible(subvol_inum inum, struct bkey_s_c k)
+{
+	struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
+
+	if (d.v->d_type == DT_SUBVOL)
+		return le32_to_cpu(d.v->d_parent_subvol) == inum.subvol;
+	return true;
+}
+
+const struct bch_hash_desc bch2_dirent_hash_desc = {
+	.btree_id	= BTREE_ID_dirents,
+	.key_type	= KEY_TYPE_dirent,
+	.hash_key	= dirent_hash_key,
+	.hash_bkey	= dirent_hash_bkey,
+	.cmp_key	= dirent_cmp_key,
+	.cmp_bkey	= dirent_cmp_bkey,
+	.is_visible	= dirent_is_visible,
+};
+
+int bch2_dirent_validate(struct bch_fs *c, struct bkey_s_c k,
+			 enum bch_validate_flags flags)
+{
+	struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
+	struct qstr d_name = bch2_dirent_get_name(d);
+	int ret = 0;
+
+	bkey_fsck_err_on(!d_name.len,
+			 c, dirent_empty_name,
+			 "empty name");
+
+	bkey_fsck_err_on(bkey_val_u64s(k.k) > dirent_val_u64s(d_name.len),
+			 c, dirent_val_too_big,
+			 "value too big (%zu > %u)",
+			 bkey_val_u64s(k.k), dirent_val_u64s(d_name.len));
+
+	/*
+	 * Check new keys don't exceed the max length
+	 * (older keys may be larger.)
+	 */
+	bkey_fsck_err_on((flags & BCH_VALIDATE_commit) && d_name.len > BCH_NAME_MAX,
+			 c, dirent_name_too_long,
+			 "dirent name too big (%u > %u)",
+			 d_name.len, BCH_NAME_MAX);
+
+	bkey_fsck_err_on(d_name.len != strnlen(d_name.name, d_name.len),
+			 c, dirent_name_embedded_nul,
+			 "dirent has stray data after name's NUL");
+
+	bkey_fsck_err_on((d_name.len == 1 && !memcmp(d_name.name, ".", 1)) ||
+			 (d_name.len == 2 && !memcmp(d_name.name, "..", 2)),
+			 c, dirent_name_dot_or_dotdot,
+			 "invalid name");
+
+	bkey_fsck_err_on(memchr(d_name.name, '/', d_name.len),
+			 c, dirent_name_has_slash,
+			 "name with /");
+
+	bkey_fsck_err_on(d.v->d_type != DT_SUBVOL &&
+			 le64_to_cpu(d.v->d_inum) == d.k->p.inode,
+			 c, dirent_to_itself,
+			 "dirent points to own directory");
+fsck_err:
+	return ret;
+}
+
+void bch2_dirent_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k)
+{
+	struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
+	struct qstr d_name = bch2_dirent_get_name(d);
+
+	prt_printf(out, "%.*s -> ", d_name.len, d_name.name);
+
+	if (d.v->d_type != DT_SUBVOL)
+		prt_printf(out, "%llu", le64_to_cpu(d.v->d_inum));
+	else
+		prt_printf(out, "%u -> %u",
+			   le32_to_cpu(d.v->d_parent_subvol),
+			   le32_to_cpu(d.v->d_child_subvol));
+
+	prt_printf(out, " type %s", bch2_d_type_str(d.v->d_type));
+}
+
+static struct bkey_i_dirent *dirent_create_key(struct btree_trans *trans,
+				subvol_inum dir, u8 type,
+				const struct qstr *name, u64 dst)
+{
+	struct bkey_i_dirent *dirent;
+	unsigned u64s = BKEY_U64s + dirent_val_u64s(name->len);
+
+	if (name->len > BCH_NAME_MAX)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	BUG_ON(u64s > U8_MAX);
+
+	dirent = bch2_trans_kmalloc(trans, u64s * sizeof(u64));
+	if (IS_ERR(dirent))
+		return dirent;
+
+	bkey_dirent_init(&dirent->k_i);
+	dirent->k.u64s = u64s;
+
+	if (type != DT_SUBVOL) {
+		dirent->v.d_inum = cpu_to_le64(dst);
+	} else {
+		dirent->v.d_parent_subvol = cpu_to_le32(dir.subvol);
+		dirent->v.d_child_subvol = cpu_to_le32(dst);
+	}
+
+	dirent->v.d_type = type;
+
+	memcpy(dirent->v.d_name, name->name, name->len);
+	memset(dirent->v.d_name + name->len, 0,
+	       bkey_val_bytes(&dirent->k) -
+	       offsetof(struct bch_dirent, d_name) -
+	       name->len);
+
+	EBUG_ON(bch2_dirent_name_bytes(dirent_i_to_s_c(dirent)) != name->len);
+
+	return dirent;
+}
+
+int bch2_dirent_create_snapshot(struct btree_trans *trans,
+			u32 dir_subvol, u64 dir, u32 snapshot,
+			const struct bch_hash_info *hash_info,
+			u8 type, const struct qstr *name, u64 dst_inum,
+			u64 *dir_offset,
+			enum btree_iter_update_trigger_flags flags)
+{
+	subvol_inum dir_inum = { .subvol = dir_subvol, .inum = dir };
+	struct bkey_i_dirent *dirent;
+	int ret;
+
+	dirent = dirent_create_key(trans, dir_inum, type, name, dst_inum);
+	ret = PTR_ERR_OR_ZERO(dirent);
+	if (ret)
+		return ret;
+
+	dirent->k.p.inode	= dir;
+	dirent->k.p.snapshot	= snapshot;
+
+	ret = bch2_hash_set_in_snapshot(trans, bch2_dirent_hash_desc, hash_info,
+					dir_inum, snapshot, &dirent->k_i,
+					flags|BTREE_UPDATE_internal_snapshot_node);
+	*dir_offset = dirent->k.p.offset;
+
+	return ret;
+}
+
+int bch2_dirent_create(struct btree_trans *trans, subvol_inum dir,
+		       const struct bch_hash_info *hash_info,
+		       u8 type, const struct qstr *name, u64 dst_inum,
+		       u64 *dir_offset,
+		       enum btree_iter_update_trigger_flags flags)
+{
+	struct bkey_i_dirent *dirent;
+	int ret;
+
+	dirent = dirent_create_key(trans, dir, type, name, dst_inum);
+	ret = PTR_ERR_OR_ZERO(dirent);
+	if (ret)
+		return ret;
+
+	ret = bch2_hash_set(trans, bch2_dirent_hash_desc, hash_info,
+			    dir, &dirent->k_i, flags);
+	*dir_offset = dirent->k.p.offset;
+
+	return ret;
+}
+
+int bch2_dirent_read_target(struct btree_trans *trans, subvol_inum dir,
+			    struct bkey_s_c_dirent d, subvol_inum *target)
+{
+	struct bch_subvolume s;
+	int ret = 0;
+
+	if (d.v->d_type == DT_SUBVOL &&
+	    le32_to_cpu(d.v->d_parent_subvol) != dir.subvol)
+		return 1;
+
+	if (likely(d.v->d_type != DT_SUBVOL)) {
+		target->subvol	= dir.subvol;
+		target->inum	= le64_to_cpu(d.v->d_inum);
+	} else {
+		target->subvol	= le32_to_cpu(d.v->d_child_subvol);
+
+		ret = bch2_subvolume_get(trans, target->subvol, true, BTREE_ITER_cached, &s);
+
+		target->inum	= le64_to_cpu(s.inode);
+	}
+
+	return ret;
+}
+
+int bch2_dirent_rename(struct btree_trans *trans,
+		subvol_inum src_dir, struct bch_hash_info *src_hash,
+		subvol_inum dst_dir, struct bch_hash_info *dst_hash,
+		const struct qstr *src_name, subvol_inum *src_inum, u64 *src_offset,
+		const struct qstr *dst_name, subvol_inum *dst_inum, u64 *dst_offset,
+		enum bch_rename_mode mode)
+{
+	struct btree_iter src_iter = { NULL };
+	struct btree_iter dst_iter = { NULL };
+	struct bkey_s_c old_src, old_dst = bkey_s_c_null;
+	struct bkey_i_dirent *new_src = NULL, *new_dst = NULL;
+	struct bpos dst_pos =
+		POS(dst_dir.inum, bch2_dirent_hash(dst_hash, dst_name));
+	unsigned src_update_flags = 0;
+	bool delete_src, delete_dst;
+	int ret = 0;
+
+	memset(src_inum, 0, sizeof(*src_inum));
+	memset(dst_inum, 0, sizeof(*dst_inum));
+
+	/* Lookup src: */
+	old_src = bch2_hash_lookup(trans, &src_iter, bch2_dirent_hash_desc,
+				   src_hash, src_dir, src_name,
+				   BTREE_ITER_intent);
+	ret = bkey_err(old_src);
+	if (ret)
+		goto out;
+
+	ret = bch2_dirent_read_target(trans, src_dir,
+			bkey_s_c_to_dirent(old_src), src_inum);
+	if (ret)
+		goto out;
+
+	/* Lookup dst: */
+	if (mode == BCH_RENAME) {
+		/*
+		 * Note that we're _not_ checking if the target already exists -
+		 * we're relying on the VFS to do that check for us for
+		 * correctness:
+		 */
+		ret = bch2_hash_hole(trans, &dst_iter, bch2_dirent_hash_desc,
+				     dst_hash, dst_dir, dst_name);
+		if (ret)
+			goto out;
+	} else {
+		old_dst = bch2_hash_lookup(trans, &dst_iter, bch2_dirent_hash_desc,
+					    dst_hash, dst_dir, dst_name,
+					    BTREE_ITER_intent);
+		ret = bkey_err(old_dst);
+		if (ret)
+			goto out;
+
+		ret = bch2_dirent_read_target(trans, dst_dir,
+				bkey_s_c_to_dirent(old_dst), dst_inum);
+		if (ret)
+			goto out;
+	}
+
+	if (mode != BCH_RENAME_EXCHANGE)
+		*src_offset = dst_iter.pos.offset;
+
+	/* Create new dst key: */
+	new_dst = dirent_create_key(trans, dst_dir, 0, dst_name, 0);
+	ret = PTR_ERR_OR_ZERO(new_dst);
+	if (ret)
+		goto out;
+
+	dirent_copy_target(new_dst, bkey_s_c_to_dirent(old_src));
+	new_dst->k.p = dst_iter.pos;
+
+	/* Create new src key: */
+	if (mode == BCH_RENAME_EXCHANGE) {
+		new_src = dirent_create_key(trans, src_dir, 0, src_name, 0);
+		ret = PTR_ERR_OR_ZERO(new_src);
+		if (ret)
+			goto out;
+
+		dirent_copy_target(new_src, bkey_s_c_to_dirent(old_dst));
+		new_src->k.p = src_iter.pos;
+	} else {
+		new_src = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
+		ret = PTR_ERR_OR_ZERO(new_src);
+		if (ret)
+			goto out;
+
+		bkey_init(&new_src->k);
+		new_src->k.p = src_iter.pos;
+
+		if (bkey_le(dst_pos, src_iter.pos) &&
+		    bkey_lt(src_iter.pos, dst_iter.pos)) {
+			/*
+			 * We have a hash collision for the new dst key,
+			 * and new_src - the key we're deleting - is between
+			 * new_dst's hashed slot and the slot we're going to be
+			 * inserting it into - oops.  This will break the hash
+			 * table if we don't deal with it:
+			 */
+			if (mode == BCH_RENAME) {
+				/*
+				 * If we're not overwriting, we can just insert
+				 * new_dst at the src position:
+				 */
+				new_src = new_dst;
+				new_src->k.p = src_iter.pos;
+				goto out_set_src;
+			} else {
+				/* If we're overwriting, we can't insert new_dst
+				 * at a different slot because it has to
+				 * overwrite old_dst - just make sure to use a
+				 * whiteout when deleting src:
+				 */
+				new_src->k.type = KEY_TYPE_hash_whiteout;
+			}
+		} else {
+			/* Check if we need a whiteout to delete src: */
+			ret = bch2_hash_needs_whiteout(trans, bch2_dirent_hash_desc,
+						       src_hash, &src_iter);
+			if (ret < 0)
+				goto out;
+
+			if (ret)
+				new_src->k.type = KEY_TYPE_hash_whiteout;
+		}
+	}
+
+	if (new_dst->v.d_type == DT_SUBVOL)
+		new_dst->v.d_parent_subvol = cpu_to_le32(dst_dir.subvol);
+
+	if ((mode == BCH_RENAME_EXCHANGE) &&
+	    new_src->v.d_type == DT_SUBVOL)
+		new_src->v.d_parent_subvol = cpu_to_le32(src_dir.subvol);
+
+	ret = bch2_trans_update(trans, &dst_iter, &new_dst->k_i, 0);
+	if (ret)
+		goto out;
+out_set_src:
+	/*
+	 * If we're deleting a subvolume we need to really delete the dirent,
+	 * not just emit a whiteout in the current snapshot - there can only be
+	 * single dirent that points to a given subvolume.
+	 *
+	 * IOW, we don't maintain multiple versions in different snapshots of
+	 * dirents that point to subvolumes - dirents that point to subvolumes
+	 * are only visible in one particular subvolume so it's not necessary,
+	 * and it would be particularly confusing for fsck to have to deal with.
+	 */
+	delete_src = bkey_s_c_to_dirent(old_src).v->d_type == DT_SUBVOL &&
+		new_src->k.p.snapshot != old_src.k->p.snapshot;
+
+	delete_dst = old_dst.k &&
+		bkey_s_c_to_dirent(old_dst).v->d_type == DT_SUBVOL &&
+		new_dst->k.p.snapshot != old_dst.k->p.snapshot;
+
+	if (!delete_src || !bkey_deleted(&new_src->k)) {
+		ret = bch2_trans_update(trans, &src_iter, &new_src->k_i, src_update_flags);
+		if (ret)
+			goto out;
+	}
+
+	if (delete_src) {
+		bch2_btree_iter_set_snapshot(&src_iter, old_src.k->p.snapshot);
+		ret =   bch2_btree_iter_traverse(&src_iter) ?:
+			bch2_btree_delete_at(trans, &src_iter, BTREE_UPDATE_internal_snapshot_node);
+		if (ret)
+			goto out;
+	}
+
+	if (delete_dst) {
+		bch2_btree_iter_set_snapshot(&dst_iter, old_dst.k->p.snapshot);
+		ret =   bch2_btree_iter_traverse(&dst_iter) ?:
+			bch2_btree_delete_at(trans, &dst_iter, BTREE_UPDATE_internal_snapshot_node);
+		if (ret)
+			goto out;
+	}
+
+	if (mode == BCH_RENAME_EXCHANGE)
+		*src_offset = new_src->k.p.offset;
+	*dst_offset = new_dst->k.p.offset;
+out:
+	bch2_trans_iter_exit(trans, &src_iter);
+	bch2_trans_iter_exit(trans, &dst_iter);
+	return ret;
+}
+
+int bch2_dirent_lookup_trans(struct btree_trans *trans,
+			     struct btree_iter *iter,
+			     subvol_inum dir,
+			     const struct bch_hash_info *hash_info,
+			     const struct qstr *name, subvol_inum *inum,
+			     unsigned flags)
+{
+	struct bkey_s_c k = bch2_hash_lookup(trans, iter, bch2_dirent_hash_desc,
+					     hash_info, dir, name, flags);
+	int ret = bkey_err(k);
+	if (ret)
+		goto err;
+
+	ret = bch2_dirent_read_target(trans, dir, bkey_s_c_to_dirent(k), inum);
+	if (ret > 0)
+		ret = -ENOENT;
+err:
+	if (ret)
+		bch2_trans_iter_exit(trans, iter);
+	return ret;
+}
+
+u64 bch2_dirent_lookup(struct bch_fs *c, subvol_inum dir,
+		       const struct bch_hash_info *hash_info,
+		       const struct qstr *name, subvol_inum *inum)
+{
+	struct btree_trans *trans = bch2_trans_get(c);
+	struct btree_iter iter = { NULL };
+
+	int ret = lockrestart_do(trans,
+		bch2_dirent_lookup_trans(trans, &iter, dir, hash_info, name, inum, 0));
+	bch2_trans_iter_exit(trans, &iter);
+	bch2_trans_put(trans);
+	return ret;
+}
+
+int bch2_empty_dir_snapshot(struct btree_trans *trans, u64 dir, u32 subvol, u32 snapshot)
+{
+	struct btree_iter iter;
+	struct bkey_s_c k;
+	int ret;
+
+	for_each_btree_key_upto_norestart(trans, iter, BTREE_ID_dirents,
+			   SPOS(dir, 0, snapshot),
+			   POS(dir, U64_MAX), 0, k, ret)
+		if (k.k->type == KEY_TYPE_dirent) {
+			struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
+			if (d.v->d_type == DT_SUBVOL && le32_to_cpu(d.v->d_parent_subvol) != subvol)
+				continue;
+			ret = -BCH_ERR_ENOTEMPTY_dir_not_empty;
+			break;
+		}
+	bch2_trans_iter_exit(trans, &iter);
+
+	return ret;
+}
+
+int bch2_empty_dir_trans(struct btree_trans *trans, subvol_inum dir)
+{
+	u32 snapshot;
+
+	return bch2_subvolume_get_snapshot(trans, dir.subvol, &snapshot) ?:
+		bch2_empty_dir_snapshot(trans, dir.inum, dir.subvol, snapshot);
+}
+
+static int bch2_dir_emit(struct dir_context *ctx, struct bkey_s_c_dirent d, subvol_inum target)
+{
+	struct qstr name = bch2_dirent_get_name(d);
+	/*
+	 * Although not required by the kernel code, updating ctx->pos is needed
+	 * for the bcachefs FUSE driver. Without this update, the FUSE
+	 * implementation will be stuck in an infinite loop when reading
+	 * directories (via the bcachefs_fuse_readdir callback).
+	 * In kernel space, ctx->pos is updated by the VFS code.
+	 */
+	ctx->pos = d.k->p.offset;
+	bool ret = dir_emit(ctx, name.name,
+		      name.len,
+		      target.inum,
+		      vfs_d_type(d.v->d_type));
+	if (ret)
+		ctx->pos = d.k->p.offset + 1;
+	return ret;
+}
+
+int bch2_readdir(struct bch_fs *c, subvol_inum inum, struct dir_context *ctx)
+{
+	struct bkey_buf sk;
+	bch2_bkey_buf_init(&sk);
+
+	int ret = bch2_trans_run(c,
+		for_each_btree_key_in_subvolume_upto(trans, iter, BTREE_ID_dirents,
+				   POS(inum.inum, ctx->pos),
+				   POS(inum.inum, U64_MAX),
+				   inum.subvol, 0, k, ({
+			if (k.k->type != KEY_TYPE_dirent)
+				continue;
+
+			/* dir_emit() can fault and block: */
+			bch2_bkey_buf_reassemble(&sk, c, k);
+			struct bkey_s_c_dirent dirent = bkey_i_to_s_c_dirent(sk.k);
+
+			subvol_inum target;
+			int ret2 = bch2_dirent_read_target(trans, inum, dirent, &target);
+			if (ret2 > 0)
+				continue;
+
+			ret2 ?: drop_locks_do(trans, bch2_dir_emit(ctx, dirent, target));
+		})));
+
+	bch2_bkey_buf_exit(&sk, c);
+
+	return ret < 0 ? ret : 0;
+}