btrfs: Remove custom crc32c init code

The custom crc32 init code was introduced in
14a958e678cd ("Btrfs: fix btrfs boot when compiled as built-in") to
enable using btrfs as a built-in. However, later as pointed out by
60efa5eb2e88 ("Btrfs: use late_initcall instead of module_init") this
wasn't enough and finally btrfs was switched to late_initcall which
comes after the generic crc32c implementation is initiliased. The
latter commit superseeded the former. Now that we don't have to
maintain our own code let's just remove it and switch to using the
generic implementation.

Despite touching a lot of files the patch is really simple. Here is the gist of
the changes:

1. Select LIBCRC32C rather than the low-level modules.
2. s/btrfs_crc32c/crc32c/g
3. replace hash.h with linux/crc32c.h
4. Move the btrfs namehash funcs to ctree.h and change the tree accordingly.

I've tested this with btrfs being both a module and a built-in and xfstest
doesn't complain.

Does seem to fix the longstanding problem of not automatically selectiong
the crc32c module when btrfs is used. Possibly there is a workaround in
dracut.

The modinfo confirms that now all the module dependencies are there:

before:
depends: zstd_compress,zstd_decompress,raid6_pq,xor,zlib_deflate

after:
depends: libcrc32c,zstd_compress,zstd_decompress,raid6_pq,xor,zlib_deflate

Signed-off-by: Nikolay Borisov <[e-mail]>
Reviewed-by: David Sterba <[e-mail]>
[ add more info to changelog from mails ]
Signed-off-by: David Sterba <[e-mail]>

fs/btrfs/Kconfig

···
 config BTRFS_FS
 	tristate "Btrfs filesystem support"
-	select CRYPTO
-	select CRYPTO_CRC32C
+	select LIBCRC32C
 	select ZLIB_INFLATE
 	select ZLIB_DEFLATE
 	select LZO_COMPRESS

fs/btrfs/Makefile

···
 	   export.o tree-log.o free-space-cache.o zlib.o lzo.o zstd.o \
 	   compression.o delayed-ref.o relocation.o delayed-inode.o scrub.o \
 	   reada.o backref.o ulist.o qgroup.o send.o dev-replace.o raid56.o \
-	   uuid-tree.o props.o hash.o free-space-tree.o tree-checker.o
+	   uuid-tree.o props.o free-space-tree.o tree-checker.o
 
 btrfs-$(CONFIG_BTRFS_FS_POSIX_ACL) += acl.o
 btrfs-$(CONFIG_BTRFS_FS_CHECK_INTEGRITY) += check-integrity.o

fs/btrfs/check-integrity.c

···
 #include <linux/blkdev.h>
 #include <linux/mm.h>
 #include <linux/string.h>
+#include <linux/crc32c.h>
 #include "ctree.h"
 #include "disk-io.h"
-#include "hash.h"
 #include "transaction.h"
 #include "extent_io.h"
 #include "volumes.h"
···
 		size_t sublen = i ? PAGE_SIZE :
 				    (PAGE_SIZE - BTRFS_CSUM_SIZE);
 
-		crc = btrfs_crc32c(crc, data, sublen);
+		crc = crc32c(crc, data, sublen);
 	}
 	btrfs_csum_final(crc, csum);
 	if (memcmp(csum, h->csum, state->csum_size))

fs/btrfs/ctree.h

···
 #include <linux/sizes.h>
 #include <linux/dynamic_debug.h>
 #include <linux/refcount.h>
+#include <linux/crc32c.h>
 #include "extent_io.h"
 #include "extent_map.h"
 #include "async-thread.h"
···
 #define BTRFS_DIRTY_METADATA_THRESH	SZ_32M
 
 #define BTRFS_MAX_EXTENT_SIZE SZ_128M
+
 
 /*
  * Count how many BTRFS_MAX_EXTENT_SIZE cover the @size
···
 #define btrfs_item_ptr_offset(leaf, slot) \
 	((unsigned long)(BTRFS_LEAF_DATA_OFFSET + \
 	btrfs_item_offset_nr(leaf, slot)))
+
+static inline u64 btrfs_name_hash(const char *name, int len)
+{
+       return crc32c((u32)~1, name, len);
+}
+
+/*
+ * Figure the key offset of an extended inode ref
+ */
+static inline u64 btrfs_extref_hash(u64 parent_objectid, const char *name,
+                                   int len)
+{
+       return (u64) crc32c(parent_objectid, name, len);
+}
 
 static inline bool btrfs_mixed_space_info(struct btrfs_space_info *space_info)
 {

fs/btrfs/dir-item.c

···
 
 #include "ctree.h"
 #include "disk-io.h"
-#include "hash.h"
 #include "transaction.h"
 
 /*

fs/btrfs/disk-io.c

···
 #include <linux/uuid.h>
 #include <linux/semaphore.h>
 #include <linux/error-injection.h>
+#include <linux/crc32c.h>
 #include <asm/unaligned.h>
 #include "ctree.h"
 #include "disk-io.h"
-#include "hash.h"
 #include "transaction.h"
 #include "btrfs_inode.h"
 #include "volumes.h"
···
 
 u32 btrfs_csum_data(const char *data, u32 seed, size_t len)
 {
-	return btrfs_crc32c(seed, data, len);
+	return crc32c(seed, data, len);
 }
 
 void btrfs_csum_final(u32 crc, u8 *result)

fs/btrfs/extent-tree.c

···
 #include <linux/ratelimit.h>
 #include <linux/percpu_counter.h>
 #include <linux/lockdep.h>
-#include "hash.h"
+#include <linux/crc32c.h>
 #include "tree-log.h"
 #include "disk-io.h"
 #include "print-tree.h"
···
 	__le64 lenum;
 
 	lenum = cpu_to_le64(root_objectid);
-	high_crc = btrfs_crc32c(high_crc, &lenum, sizeof(lenum));
+	high_crc = crc32c(high_crc, &lenum, sizeof(lenum));
 	lenum = cpu_to_le64(owner);
-	low_crc = btrfs_crc32c(low_crc, &lenum, sizeof(lenum));
+	low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
 	lenum = cpu_to_le64(offset);
-	low_crc = btrfs_crc32c(low_crc, &lenum, sizeof(lenum));
+	low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
 
 	return ((u64)high_crc << 31) ^ (u64)low_crc;
 }
···
 	 */
 	u64 num_bytes = btrfs_calc_trans_metadata_size(fs_info, 1);
 
-	trace_btrfs_space_reservation(fs_info, "orphan", btrfs_ino(inode), 
+	trace_btrfs_space_reservation(fs_info, "orphan", btrfs_ino(inode),
 			num_bytes, 1);
 	return btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes, 1);
 }

fs/btrfs/hash.c

···
-/*
- * Copyright (C) 2014 Filipe David Borba Manana <[e-mail]>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public
- * License v2 as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * General Public License for more details.
- */
-
-#include <crypto/hash.h>
-#include <linux/err.h>
-#include "hash.h"
-
-static struct crypto_shash *tfm;
-
-int __init btrfs_hash_init(void)
-{
-	tfm = crypto_alloc_shash("crc32c", 0, 0);
-
-	return PTR_ERR_OR_ZERO(tfm);
-}
-
-const char* btrfs_crc32c_impl(void)
-{
-	return crypto_tfm_alg_driver_name(crypto_shash_tfm(tfm));
-}
-
-void btrfs_hash_exit(void)
-{
-	crypto_free_shash(tfm);
-}
-
-u32 btrfs_crc32c(u32 crc, const void *address, unsigned int length)
-{
-	SHASH_DESC_ON_STACK(shash, tfm);
-	u32 *ctx = (u32 *)shash_desc_ctx(shash);
-	u32 retval;
-	int err;
-
-	shash->tfm = tfm;
-	shash->flags = 0;
-	*ctx = crc;
-
-	err = crypto_shash_update(shash, address, length);
-	BUG_ON(err);
-
-	retval = *ctx;
-	barrier_data(ctx);
-	return retval;
-}

fs/btrfs/hash.h

···
-/*
- * Copyright (C) 2007 Oracle.  All rights reserved.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public
- * License v2 as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public
- * License along with this program; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 021110-1307, USA.
- */
-
-#ifndef __HASH__
-#define __HASH__
-
-int __init btrfs_hash_init(void);
-
-void btrfs_hash_exit(void);
-const char* btrfs_crc32c_impl(void);
-
-u32 btrfs_crc32c(u32 crc, const void *address, unsigned int length);
-
-static inline u64 btrfs_name_hash(const char *name, int len)
-{
-	return btrfs_crc32c((u32)~1, name, len);
-}
-
-/*
- * Figure the key offset of an extended inode ref
- */
-static inline u64 btrfs_extref_hash(u64 parent_objectid, const char *name,
-				    int len)
-{
-	return (u64) btrfs_crc32c(parent_objectid, name, len);
-}
-
-#endif

fs/btrfs/inode-item.c

···
 
 #include "ctree.h"
 #include "disk-io.h"
-#include "hash.h"
 #include "transaction.h"
 #include "print-tree.h"
 

fs/btrfs/inode.c

···
 #include "free-space-cache.h"
 #include "inode-map.h"
 #include "backref.h"
-#include "hash.h"
 #include "props.h"
 #include "qgroup.h"
 #include "dedupe.h"

fs/btrfs/props.c

···
 #include <linux/hashtable.h>
 #include "props.h"
 #include "btrfs_inode.h"
-#include "hash.h"
 #include "transaction.h"
+#include "ctree.h"
 #include "xattr.h"
 #include "compression.h"
 

fs/btrfs/send.c

···
 #include <linux/vmalloc.h>
 #include <linux/string.h>
 #include <linux/compat.h>
+#include <linux/crc32c.h>
 
 #include "send.h"
 #include "backref.h"
-#include "hash.h"
 #include "locking.h"
 #include "disk-io.h"
 #include "btrfs_inode.h"
···
 	hdr->len = cpu_to_le32(sctx->send_size - sizeof(*hdr));
 	hdr->crc = 0;
 
-	crc = btrfs_crc32c(0, (unsigned char *)sctx->send_buf, sctx->send_size);
+	crc = crc32c(0, (unsigned char *)sctx->send_buf, sctx->send_size);
 	hdr->crc = cpu_to_le32(crc);
 
 	ret = write_buf(sctx->send_filp, sctx->send_buf, sctx->send_size,

fs/btrfs/super.c

···
 #include <linux/slab.h>
 #include <linux/cleancache.h>
 #include <linux/ratelimit.h>
+#include <linux/crc32c.h>
 #include <linux/btrfs.h>
 #include "delayed-inode.h"
 #include "ctree.h"
···
 #include "transaction.h"
 #include "btrfs_inode.h"
 #include "print-tree.h"
-#include "hash.h"
 #include "props.h"
 #include "xattr.h"
 #include "volumes.h"
···
 			", ref-verify=on"
 #endif
 			"\n",
-			btrfs_crc32c_impl());
+			crc32c_impl());
 }
 
 static int __init init_btrfs_fs(void)
 {
 	int err;
 
-	err = btrfs_hash_init();
-	if (err)
-		return err;
-
 	btrfs_props_init();
 
 	err = btrfs_init_sysfs();
 	if (err)
-		goto free_hash;
+		return err;
 
 	btrfs_init_compress();
 
···
 free_compress:
 	btrfs_exit_compress();
 	btrfs_exit_sysfs();
-free_hash:
-	btrfs_hash_exit();
+
 	return err;
 }
 
···
 	btrfs_exit_sysfs();
 	btrfs_cleanup_fs_uuids();
 	btrfs_exit_compress();
-	btrfs_hash_exit();
 }
 
 late_initcall(init_btrfs_fs);

fs/btrfs/tree-checker.c

···
 #include "tree-checker.h"
 #include "disk-io.h"
 #include "compression.h"
-#include "hash.h"
 
 /*
  * Error message should follow the following format:

fs/btrfs/tree-log.c

···
 #include <linux/blkdev.h>
 #include <linux/list_sort.h>
 #include <linux/iversion.h>
+#include "ctree.h"
 #include "tree-log.h"
 #include "disk-io.h"
 #include "locking.h"
 #include "print-tree.h"
 #include "backref.h"
-#include "hash.h"
 #include "compression.h"
 #include "qgroup.h"
 #include "inode-map.h"