kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 568 insertions, 0 deletions

diff --git a/fs/nilfs2/bmap.c b/fs/nilfs2/bmap.c
new file mode 100644
index 000000000..83f6ea30c
--- /dev/null
+++ b/fs/nilfs2/bmap.c
@@ -0,0 +1,568 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * NILFS block mapping.
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * Written by Koji Sato.
+ */
+
+#include <linux/fs.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include "nilfs.h"
+#include "bmap.h"
+#include "btree.h"
+#include "direct.h"
+#include "btnode.h"
+#include "mdt.h"
+#include "dat.h"
+#include "alloc.h"
+
+struct inode *nilfs_bmap_get_dat(const struct nilfs_bmap *bmap)
+{
+	struct the_nilfs *nilfs = bmap->b_inode->i_sb->s_fs_info;
+
+	return nilfs->ns_dat;
+}
+
+static int nilfs_bmap_convert_error(struct nilfs_bmap *bmap,
+				     const char *fname, int err)
+{
+	struct inode *inode = bmap->b_inode;
+
+	if (err == -EINVAL) {
+		__nilfs_error(inode->i_sb, fname,
+			      "broken bmap (inode number=%llu)", inode->i_ino);
+		err = -EIO;
+	}
+	return err;
+}
+
+/**
+ * nilfs_bmap_lookup_at_level - find a data block or node block
+ * @bmap: bmap
+ * @key: key
+ * @level: level
+ * @ptrp: place to store the value associated to @key
+ *
+ * Description: nilfs_bmap_lookup_at_level() finds a record whose key
+ * matches @key in the block at @level of the bmap.  The record associated
+ * with @key is stored in the place pointed to by @ptrp.
+ *
+ * Return: 0 on success, or one of the following negative error codes on
+ * failure:
+ * * %-EIO	- I/O error (including metadata corruption).
+ * * %-ENOENT	- A record associated with @key does not exist.
+ * * %-ENOMEM	- Insufficient memory available.
+ */
+int nilfs_bmap_lookup_at_level(struct nilfs_bmap *bmap, __u64 key, int level,
+			       __u64 *ptrp)
+{
+	sector_t blocknr;
+	int ret;
+
+	down_read(&bmap->b_sem);
+	ret = bmap->b_ops->bop_lookup(bmap, key, level, ptrp);
+	if (ret < 0)
+		goto out;
+
+	if (NILFS_BMAP_USE_VBN(bmap)) {
+		ret = nilfs_dat_translate(nilfs_bmap_get_dat(bmap), *ptrp,
+					  &blocknr);
+		if (!ret)
+			*ptrp = blocknr;
+		else if (ret == -ENOENT) {
+			/*
+			 * If there was no valid entry in DAT for the block
+			 * address obtained by b_ops->bop_lookup, then pass
+			 * internal code -EINVAL to nilfs_bmap_convert_error
+			 * to treat it as metadata corruption.
+			 */
+			ret = -EINVAL;
+		}
+	}
+
+ out:
+	up_read(&bmap->b_sem);
+	return nilfs_bmap_convert_error(bmap, __func__, ret);
+}
+
+int nilfs_bmap_lookup_contig(struct nilfs_bmap *bmap, __u64 key, __u64 *ptrp,
+			     unsigned int maxblocks)
+{
+	int ret;
+
+	down_read(&bmap->b_sem);
+	ret = bmap->b_ops->bop_lookup_contig(bmap, key, ptrp, maxblocks);
+	up_read(&bmap->b_sem);
+
+	return nilfs_bmap_convert_error(bmap, __func__, ret);
+}
+
+static int nilfs_bmap_do_insert(struct nilfs_bmap *bmap, __u64 key, __u64 ptr)
+{
+	__u64 keys[NILFS_BMAP_SMALL_HIGH + 1];
+	__u64 ptrs[NILFS_BMAP_SMALL_HIGH + 1];
+	int ret, n;
+
+	if (bmap->b_ops->bop_check_insert != NULL) {
+		ret = bmap->b_ops->bop_check_insert(bmap, key);
+		if (ret > 0) {
+			n = bmap->b_ops->bop_gather_data(
+				bmap, keys, ptrs, NILFS_BMAP_SMALL_HIGH + 1);
+			if (n < 0)
+				return n;
+			ret = nilfs_btree_convert_and_insert(
+				bmap, key, ptr, keys, ptrs, n);
+			if (ret == 0)
+				bmap->b_u.u_flags |= NILFS_BMAP_LARGE;
+
+			return ret;
+		} else if (ret < 0)
+			return ret;
+	}
+
+	return bmap->b_ops->bop_insert(bmap, key, ptr);
+}
+
+/**
+ * nilfs_bmap_insert - insert a new key-record pair into a bmap
+ * @bmap: bmap
+ * @key: key
+ * @rec: record
+ *
+ * Description: nilfs_bmap_insert() inserts the new key-record pair specified
+ * by @key and @rec into @bmap.
+ *
+ * Return: 0 on success, or one of the following negative error codes on
+ * failure:
+ * * %-EEXIST	- A record associated with @key already exists.
+ * * %-EIO	- I/O error (including metadata corruption).
+ * * %-ENOMEM	- Insufficient memory available.
+ */
+int nilfs_bmap_insert(struct nilfs_bmap *bmap, __u64 key, unsigned long rec)
+{
+	int ret;
+
+	down_write(&bmap->b_sem);
+	ret = nilfs_bmap_do_insert(bmap, key, rec);
+	up_write(&bmap->b_sem);
+
+	return nilfs_bmap_convert_error(bmap, __func__, ret);
+}
+
+static int nilfs_bmap_do_delete(struct nilfs_bmap *bmap, __u64 key)
+{
+	__u64 keys[NILFS_BMAP_LARGE_LOW + 1];
+	__u64 ptrs[NILFS_BMAP_LARGE_LOW + 1];
+	int ret, n;
+
+	if (bmap->b_ops->bop_check_delete != NULL) {
+		ret = bmap->b_ops->bop_check_delete(bmap, key);
+		if (ret > 0) {
+			n = bmap->b_ops->bop_gather_data(
+				bmap, keys, ptrs, NILFS_BMAP_LARGE_LOW + 1);
+			if (n < 0)
+				return n;
+			ret = nilfs_direct_delete_and_convert(
+				bmap, key, keys, ptrs, n);
+			if (ret == 0)
+				bmap->b_u.u_flags &= ~NILFS_BMAP_LARGE;
+
+			return ret;
+		} else if (ret < 0)
+			return ret;
+	}
+
+	return bmap->b_ops->bop_delete(bmap, key, false);
+}
+
+/**
+ * nilfs_bmap_seek_key - seek a valid entry and return its key
+ * @bmap: bmap struct
+ * @start: start key number
+ * @keyp: place to store valid key
+ *
+ * Description: nilfs_bmap_seek_key() seeks a valid key on @bmap
+ * starting from @start, and stores it to @keyp if found.
+ *
+ * Return: 0 on success, or one of the following negative error codes on
+ * failure:
+ * * %-EIO	- I/O error (including metadata corruption).
+ * * %-ENOENT	- No valid entry was found.
+ * * %-ENOMEM	- Insufficient memory available.
+ */
+int nilfs_bmap_seek_key(struct nilfs_bmap *bmap, __u64 start, __u64 *keyp)
+{
+	int ret;
+
+	down_read(&bmap->b_sem);
+	ret = bmap->b_ops->bop_seek_key(bmap, start, keyp);
+	up_read(&bmap->b_sem);
+
+	if (ret < 0)
+		ret = nilfs_bmap_convert_error(bmap, __func__, ret);
+	return ret;
+}
+
+int nilfs_bmap_last_key(struct nilfs_bmap *bmap, __u64 *keyp)
+{
+	int ret;
+
+	down_read(&bmap->b_sem);
+	ret = bmap->b_ops->bop_last_key(bmap, keyp);
+	up_read(&bmap->b_sem);
+
+	if (ret < 0)
+		ret = nilfs_bmap_convert_error(bmap, __func__, ret);
+	return ret;
+}
+
+/**
+ * nilfs_bmap_delete - delete a key-record pair from a bmap
+ * @bmap: bmap
+ * @key: key
+ *
+ * Description: nilfs_bmap_delete() deletes the key-record pair specified by
+ * @key from @bmap.
+ *
+ * Return: 0 on success, or one of the following negative error codes on
+ * failure:
+ * * %-EIO	- I/O error (including metadata corruption).
+ * * %-ENOENT	- A record associated with @key does not exist.
+ * * %-ENOMEM	- Insufficient memory available.
+ */
+int nilfs_bmap_delete(struct nilfs_bmap *bmap, __u64 key)
+{
+	int ret;
+
+	down_write(&bmap->b_sem);
+	ret = nilfs_bmap_do_delete(bmap, key);
+	up_write(&bmap->b_sem);
+
+	return nilfs_bmap_convert_error(bmap, __func__, ret);
+}
+
+static int nilfs_bmap_do_truncate(struct nilfs_bmap *bmap, __u64 key)
+{
+	__u64 lastkey;
+	int ret;
+
+	ret = bmap->b_ops->bop_last_key(bmap, &lastkey);
+	if (ret < 0) {
+		if (ret == -ENOENT)
+			ret = 0;
+		return ret;
+	}
+
+	while (key <= lastkey) {
+		ret = nilfs_bmap_do_delete(bmap, lastkey);
+		if (ret < 0)
+			return ret;
+		ret = bmap->b_ops->bop_last_key(bmap, &lastkey);
+		if (ret < 0) {
+			if (ret == -ENOENT)
+				ret = 0;
+			return ret;
+		}
+	}
+	return 0;
+}
+
+/**
+ * nilfs_bmap_truncate - truncate a bmap to a specified key
+ * @bmap: bmap
+ * @key: key
+ *
+ * Description: nilfs_bmap_truncate() removes key-record pairs whose keys are
+ * greater than or equal to @key from @bmap.
+ *
+ * Return: 0 on success, or one of the following negative error codes on
+ * failure:
+ * * %-EIO	- I/O error (including metadata corruption).
+ * * %-ENOMEM	- Insufficient memory available.
+ */
+int nilfs_bmap_truncate(struct nilfs_bmap *bmap, __u64 key)
+{
+	int ret;
+
+	down_write(&bmap->b_sem);
+	ret = nilfs_bmap_do_truncate(bmap, key);
+	up_write(&bmap->b_sem);
+
+	return nilfs_bmap_convert_error(bmap, __func__, ret);
+}
+
+/**
+ * nilfs_bmap_clear - free resources a bmap holds
+ * @bmap: bmap
+ *
+ * Description: nilfs_bmap_clear() frees resources associated with @bmap.
+ */
+void nilfs_bmap_clear(struct nilfs_bmap *bmap)
+{
+	down_write(&bmap->b_sem);
+	if (bmap->b_ops->bop_clear != NULL)
+		bmap->b_ops->bop_clear(bmap);
+	up_write(&bmap->b_sem);
+}
+
+/**
+ * nilfs_bmap_propagate - propagate dirty state
+ * @bmap: bmap
+ * @bh: buffer head
+ *
+ * Description: nilfs_bmap_propagate() marks the buffers that directly or
+ * indirectly refer to the block specified by @bh dirty.
+ *
+ * Return: 0 on success, or one of the following negative error codes on
+ * failure:
+ * * %-EIO	- I/O error (including metadata corruption).
+ * * %-ENOMEM	- Insufficient memory available.
+ */
+int nilfs_bmap_propagate(struct nilfs_bmap *bmap, struct buffer_head *bh)
+{
+	int ret;
+
+	down_write(&bmap->b_sem);
+	ret = bmap->b_ops->bop_propagate(bmap, bh);
+	up_write(&bmap->b_sem);
+
+	return nilfs_bmap_convert_error(bmap, __func__, ret);
+}
+
+/**
+ * nilfs_bmap_lookup_dirty_buffers - collect dirty block buffers
+ * @bmap: bmap
+ * @listp: pointer to buffer head list
+ */
+void nilfs_bmap_lookup_dirty_buffers(struct nilfs_bmap *bmap,
+				     struct list_head *listp)
+{
+	if (bmap->b_ops->bop_lookup_dirty_buffers != NULL)
+		bmap->b_ops->bop_lookup_dirty_buffers(bmap, listp);
+}
+
+/**
+ * nilfs_bmap_assign - assign a new block number to a block
+ * @bmap:    bmap
+ * @bh:      place to store a pointer to the buffer head to which a block
+ *           address is assigned (in/out)
+ * @blocknr: block number
+ * @binfo:   block information
+ *
+ * Description: nilfs_bmap_assign() assigns the block number @blocknr to the
+ * buffer specified by @bh.  The block information is stored in the memory
+ * pointed to by @binfo, and the buffer head may be replaced as a block
+ * address is assigned, in which case a pointer to the new buffer head is
+ * stored in the memory pointed to by @bh.
+ *
+ * Return: 0 on success, or one of the following negative error codes on
+ * failure:
+ * * %-EIO	- I/O error (including metadata corruption).
+ * * %-ENOMEM	- Insufficient memory available.
+ */
+int nilfs_bmap_assign(struct nilfs_bmap *bmap,
+		      struct buffer_head **bh,
+		      unsigned long blocknr,
+		      union nilfs_binfo *binfo)
+{
+	int ret;
+
+	down_write(&bmap->b_sem);
+	ret = bmap->b_ops->bop_assign(bmap, bh, blocknr, binfo);
+	up_write(&bmap->b_sem);
+
+	return nilfs_bmap_convert_error(bmap, __func__, ret);
+}
+
+/**
+ * nilfs_bmap_mark - mark block dirty
+ * @bmap: bmap
+ * @key: key
+ * @level: level
+ *
+ * Description: nilfs_bmap_mark() marks the block specified by @key and @level
+ * as dirty.
+ *
+ * Return: 0 on success, or one of the following negative error codes on
+ * failure:
+ * * %-EIO	- I/O error (including metadata corruption).
+ * * %-ENOMEM	- Insufficient memory available.
+ */
+int nilfs_bmap_mark(struct nilfs_bmap *bmap, __u64 key, int level)
+{
+	int ret;
+
+	if (bmap->b_ops->bop_mark == NULL)
+		return 0;
+
+	down_write(&bmap->b_sem);
+	ret = bmap->b_ops->bop_mark(bmap, key, level);
+	up_write(&bmap->b_sem);
+
+	return nilfs_bmap_convert_error(bmap, __func__, ret);
+}
+
+/**
+ * nilfs_bmap_test_and_clear_dirty - test and clear a bmap dirty state
+ * @bmap: bmap
+ *
+ * Description: nilfs_test_and_clear() is the atomic operation to test and
+ * clear the dirty state of @bmap.
+ *
+ * Return: 1 if @bmap is dirty, or 0 if clear.
+ */
+int nilfs_bmap_test_and_clear_dirty(struct nilfs_bmap *bmap)
+{
+	int ret;
+
+	down_write(&bmap->b_sem);
+	ret = nilfs_bmap_dirty(bmap);
+	nilfs_bmap_clear_dirty(bmap);
+	up_write(&bmap->b_sem);
+	return ret;
+}
+
+
+/*
+ * Internal use only
+ */
+__u64 nilfs_bmap_data_get_key(const struct nilfs_bmap *bmap,
+			      const struct buffer_head *bh)
+{
+	loff_t pos = folio_pos(bh->b_folio) + bh_offset(bh);
+
+	return pos >> bmap->b_inode->i_blkbits;
+}
+
+__u64 nilfs_bmap_find_target_seq(const struct nilfs_bmap *bmap, __u64 key)
+{
+	__s64 diff;
+
+	diff = key - bmap->b_last_allocated_key;
+	if ((nilfs_bmap_keydiff_abs(diff) < NILFS_INODE_BMAP_SIZE) &&
+	    (bmap->b_last_allocated_ptr != NILFS_BMAP_INVALID_PTR) &&
+	    (bmap->b_last_allocated_ptr + diff > 0))
+		return bmap->b_last_allocated_ptr + diff;
+	else
+		return NILFS_BMAP_INVALID_PTR;
+}
+
+#define NILFS_BMAP_GROUP_DIV	8	/* must be power of 2 */
+
+__u64 nilfs_bmap_find_target_in_group(const struct nilfs_bmap *bmap)
+{
+	struct inode *dat = nilfs_bmap_get_dat(bmap);
+	unsigned long entries_per_group = nilfs_palloc_entries_per_group(dat);
+	unsigned long group;
+	u32 index;
+
+	BUILD_BUG_ON_NOT_POWER_OF_2(NILFS_BMAP_GROUP_DIV);
+
+	group = div_u64(bmap->b_inode->i_ino, entries_per_group);
+	index = bmap->b_inode->i_ino & (NILFS_BMAP_GROUP_DIV - 1);
+
+	return group * entries_per_group +
+	       index * (entries_per_group / NILFS_BMAP_GROUP_DIV);
+}
+
+
+static struct lock_class_key nilfs_bmap_dat_lock_key;
+static struct lock_class_key nilfs_bmap_mdt_lock_key;
+
+/**
+ * nilfs_bmap_read - read a bmap from an inode
+ * @bmap: bmap
+ * @raw_inode: on-disk inode
+ *
+ * Description: nilfs_bmap_read() initializes the bmap @bmap.
+ *
+ * Return: 0 on success, or one of the following negative error codes on
+ * failure:
+ * * %-EIO	- I/O error (corrupted bmap).
+ * * %-ENOMEM	- Insufficient memory available.
+ */
+int nilfs_bmap_read(struct nilfs_bmap *bmap, struct nilfs_inode *raw_inode)
+{
+	if (raw_inode == NULL)
+		memset(bmap->b_u.u_data, 0, NILFS_BMAP_SIZE);
+	else
+		memcpy(bmap->b_u.u_data, raw_inode->i_bmap, NILFS_BMAP_SIZE);
+
+	init_rwsem(&bmap->b_sem);
+	bmap->b_state = 0;
+	bmap->b_inode = &NILFS_BMAP_I(bmap)->vfs_inode;
+	switch (bmap->b_inode->i_ino) {
+	case NILFS_DAT_INO:
+		bmap->b_ptr_type = NILFS_BMAP_PTR_P;
+		bmap->b_last_allocated_key = 0;
+		bmap->b_last_allocated_ptr = NILFS_BMAP_NEW_PTR_INIT;
+		lockdep_set_class(&bmap->b_sem, &nilfs_bmap_dat_lock_key);
+		break;
+	case NILFS_CPFILE_INO:
+	case NILFS_SUFILE_INO:
+		bmap->b_ptr_type = NILFS_BMAP_PTR_VS;
+		bmap->b_last_allocated_key = 0;
+		bmap->b_last_allocated_ptr = NILFS_BMAP_INVALID_PTR;
+		lockdep_set_class(&bmap->b_sem, &nilfs_bmap_mdt_lock_key);
+		break;
+	case NILFS_IFILE_INO:
+		lockdep_set_class(&bmap->b_sem, &nilfs_bmap_mdt_lock_key);
+		fallthrough;
+	default:
+		bmap->b_ptr_type = NILFS_BMAP_PTR_VM;
+		bmap->b_last_allocated_key = 0;
+		bmap->b_last_allocated_ptr = NILFS_BMAP_INVALID_PTR;
+		break;
+	}
+
+	return (bmap->b_u.u_flags & NILFS_BMAP_LARGE) ?
+		nilfs_btree_init(bmap) : nilfs_direct_init(bmap);
+}
+
+/**
+ * nilfs_bmap_write - write back a bmap to an inode
+ * @bmap: bmap
+ * @raw_inode: on-disk inode
+ *
+ * Description: nilfs_bmap_write() stores @bmap in @raw_inode.
+ */
+void nilfs_bmap_write(struct nilfs_bmap *bmap, struct nilfs_inode *raw_inode)
+{
+	memcpy(raw_inode->i_bmap, bmap->b_u.u_data,
+	       NILFS_INODE_BMAP_SIZE * sizeof(__le64));
+	if (bmap->b_inode->i_ino == NILFS_DAT_INO)
+		bmap->b_last_allocated_ptr = NILFS_BMAP_NEW_PTR_INIT;
+}
+
+void nilfs_bmap_init_gc(struct nilfs_bmap *bmap)
+{
+	memset(&bmap->b_u, 0, NILFS_BMAP_SIZE);
+	init_rwsem(&bmap->b_sem);
+	bmap->b_inode = &NILFS_BMAP_I(bmap)->vfs_inode;
+	bmap->b_ptr_type = NILFS_BMAP_PTR_U;
+	bmap->b_last_allocated_key = 0;
+	bmap->b_last_allocated_ptr = NILFS_BMAP_INVALID_PTR;
+	bmap->b_state = 0;
+	nilfs_btree_init_gc(bmap);
+}
+
+void nilfs_bmap_save(const struct nilfs_bmap *bmap,
+		     struct nilfs_bmap_store *store)
+{
+	memcpy(store->data, bmap->b_u.u_data, sizeof(store->data));
+	store->last_allocated_key = bmap->b_last_allocated_key;
+	store->last_allocated_ptr = bmap->b_last_allocated_ptr;
+	store->state = bmap->b_state;
+}
+
+void nilfs_bmap_restore(struct nilfs_bmap *bmap,
+			const struct nilfs_bmap_store *store)
+{
+	memcpy(bmap->b_u.u_data, store->data, sizeof(store->data));
+	bmap->b_last_allocated_key = store->last_allocated_key;
+	bmap->b_last_allocated_ptr = store->last_allocated_ptr;
+	bmap->b_state = store->state;
+}