Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751747AbYBKBMh (ORCPT ); Sun, 10 Feb 2008 20:12:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755989AbYBKBM0 (ORCPT ); Sun, 10 Feb 2008 20:12:26 -0500 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:41518 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1755969AbYBKBMZ (ORCPT ); Sun, 10 Feb 2008 20:12:25 -0500 Date: Sun, 10 Feb 2008 17:12:57 -0800 (PST) Message-Id: <20080210.171257.233096646.davem@davemloft.net> To: chris.mason@oracle.com Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, btrfs-devel@oss.oracle.com Subject: Re: [ANNOUNCE] Btrfs v0.12 released From: David Miller In-Reply-To: <200802061200.14690.chris.mason@oracle.com> References: <200802061200.14690.chris.mason@oracle.com> X-Mailer: Mew version 5.2 on Emacs 22.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6752 Lines: 173 From: Chris Mason Date: Wed, 6 Feb 2008 12:00:13 -0500 > So, here's v0.12. I couldn't even make a filesystem on sparc64 without the following patch. The first problem is that these SETGET macros lose typing information, and therefore can't see the 'packed' attribute and therefore take unaligned access SIGBUS signals on sparc64 when trying to derefernce the member. The next problem is a similar issue in btrfs_name_hash(). This gets passed things like &key.offset which is a member of a packed structure, losing this packed'ness information btrfs_name_hash() performs a potentially unaligned memory access, again resulting in a SIGBUS. This function never returns an error, so the simplest fix was to return the hash value which avoids all of the issues. In attempting other schemes to fix this, I found it very difficult to give gcc a packed attribute for that "u64 *" argument other than to create some new pseudo structure which would have been ugly. Similar code lives in the btrfs kernel code too, I'll try to get a partition at least mounted and working minimally and if successful I'll send you patches for that too. diff -up --recursive --new-file vanilla/btrfs-progs-0.12/ctree.h btrfs-progs-0.12/ctree.h --- vanilla/btrfs-progs-0.12/ctree.h 2008-02-06 08:37:45.000000000 -0800 +++ btrfs-progs-0.12/ctree.h 2008-02-10 16:53:24.000000000 -0800 @@ -451,18 +451,16 @@ static inline void btrfs_set_##name(stru static inline u##bits btrfs_##name(struct extent_buffer *eb, \ type *s) \ { \ - unsigned long offset = (unsigned long)s + \ - offsetof(type, member); \ - __le##bits *tmp = (__le##bits *)(eb->data + offset); \ - return le##bits##_to_cpu(*tmp); \ + unsigned long offset = (unsigned long)s; \ + type *p = (type *) (eb->data + offset); \ + return le##bits##_to_cpu(p->member); \ } \ static inline void btrfs_set_##name(struct extent_buffer *eb, \ type *s, u##bits val) \ { \ - unsigned long offset = (unsigned long)s + \ - offsetof(type, member); \ - __le##bits *tmp = (__le##bits *)(eb->data + offset); \ - *tmp = cpu_to_le##bits(val); \ + unsigned long offset = (unsigned long)s; \ + type *p = (type *) (eb->data + offset); \ + p->member = cpu_to_le##bits(val); \ } #define BTRFS_SETGET_STACK_FUNCS(name, type, member, bits) \ diff -up --recursive --new-file vanilla/btrfs-progs-0.12/dir-item.c btrfs-progs-0.12/dir-item.c --- vanilla/btrfs-progs-0.12/dir-item.c 2008-02-06 08:37:45.000000000 -0800 +++ btrfs-progs-0.12/dir-item.c 2008-02-10 17:03:34.000000000 -0800 @@ -71,8 +71,7 @@ int btrfs_insert_xattr_item(struct btrfs key.objectid = dir; btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY); - ret = btrfs_name_hash(name, name_len, &key.offset); - BUG_ON(ret); + key.offset = btrfs_name_hash(name, name_len); path = btrfs_alloc_path(); if (!path) return -ENOMEM; @@ -122,8 +121,7 @@ int btrfs_insert_dir_item(struct btrfs_t key.objectid = dir; btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY); - ret = btrfs_name_hash(name, name_len, &key.offset); - BUG_ON(ret); + key.offset = btrfs_name_hash(name, name_len); path = btrfs_alloc_path(); data_size = sizeof(*dir_item) + name_len; dir_item = insert_with_overflow(trans, root, path, &key, data_size, @@ -196,8 +194,7 @@ struct btrfs_dir_item *btrfs_lookup_dir_ key.objectid = dir; btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY); - ret = btrfs_name_hash(name, name_len, &key.offset); - BUG_ON(ret); + key.offset = btrfs_name_hash(name, name_len); ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow); if (ret < 0) @@ -258,8 +255,7 @@ struct btrfs_dir_item *btrfs_lookup_xatt key.objectid = dir; btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY); - ret = btrfs_name_hash(name, name_len, &key.offset); - BUG_ON(ret); + key.offset = btrfs_name_hash(name, name_len); ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow); if (ret < 0) return ERR_PTR(ret); diff -up --recursive --new-file vanilla/btrfs-progs-0.12/dir-test.c btrfs-progs-0.12/dir-test.c --- vanilla/btrfs-progs-0.12/dir-test.c 2008-02-06 08:37:45.000000000 -0800 +++ btrfs-progs-0.12/dir-test.c 2008-02-10 17:03:49.000000000 -0800 @@ -129,8 +129,8 @@ error: struct btrfs_dir_item); found = (char *)(di + 1); found_len = btrfs_dir_name_len(di); - btrfs_name_hash(buf, strlen(buf), &myhash); - btrfs_name_hash(found, found_len, &foundhash); + myhash = btrfs_name_hash(buf, strlen(buf)); + foundhash = btrfs_name_hash(found, found_len); if (myhash != foundhash) goto fatal_release; btrfs_release_path(root, &path); diff -up --recursive --new-file vanilla/btrfs-progs-0.12/hash.c btrfs-progs-0.12/hash.c --- vanilla/btrfs-progs-0.12/hash.c 2008-02-06 08:37:45.000000000 -0800 +++ btrfs-progs-0.12/hash.c 2008-02-10 17:02:36.000000000 -0800 @@ -75,12 +75,13 @@ static void str2hashbuf(const char *msg, *buf++ = pad; } -int btrfs_name_hash(const char *name, int len, u64 *hash_result) +u64 btrfs_name_hash(const char *name, int len) { __u32 hash; __u32 minor_hash = 0; const char *p; __u32 in[8], buf[2]; + u64 hash_result; /* Initialize the default seed for the hash checksum functions */ buf[0] = 0x67452301; @@ -97,8 +98,8 @@ int btrfs_name_hash(const char *name, in } hash = buf[0]; minor_hash = buf[1]; - *hash_result = buf[0]; - *hash_result <<= 32; - *hash_result |= buf[1]; - return 0; + hash_result = buf[0]; + hash_result <<= 32; + hash_result |= buf[1]; + return hash_result; } diff -up --recursive --new-file vanilla/btrfs-progs-0.12/hash.h btrfs-progs-0.12/hash.h --- vanilla/btrfs-progs-0.12/hash.h 2008-02-06 08:37:45.000000000 -0800 +++ btrfs-progs-0.12/hash.h 2008-02-10 17:02:21.000000000 -0800 @@ -18,5 +18,5 @@ #ifndef __HASH__ #define __HASH__ -int btrfs_name_hash(const char *name, int len, u64 *hash_result); +u64 btrfs_name_hash(const char *name, int len); #endif diff -up --recursive --new-file vanilla/btrfs-progs-0.12/hasher.c btrfs-progs-0.12/hasher.c --- vanilla/btrfs-progs-0.12/hasher.c 2008-02-06 08:37:45.000000000 -0800 +++ btrfs-progs-0.12/hasher.c 2008-02-10 17:04:04.000000000 -0800 @@ -35,8 +35,7 @@ int main() { continue; if (line[strlen(line)-1] == '\n') line[strlen(line)-1] = '\0'; - ret = btrfs_name_hash(line, strlen(line), &result); - BUG_ON(ret); + result = btrfs_name_hash(line, strlen(line)); printf("hash returns %llu\n", (unsigned long long)result); } return 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/