From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754144Ab1AYWTK (ORCPT ); Tue, 25 Jan 2011 17:19:10 -0500 Received: from moutng.kundenserver.de ([212.227.126.171]:62612 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753557Ab1AYWSE (ORCPT ); Tue, 25 Jan 2011 17:18:04 -0500 From: Arnd Bergmann To: linux-kernel@vger.kernel.org Cc: Arnd Bergmann , Mikulas Patocka , linux-fsdevel@vger.kernel.org Subject: [PATCH 10/20] hpfs: replace BKL with a global mutex Date: Tue, 25 Jan 2011 23:17:24 +0100 Message-Id: <1295993854-4971-11-git-send-email-arnd@arndb.de> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1295993854-4971-1-git-send-email-arnd@arndb.de> References: <1295993854-4971-1-git-send-email-arnd@arndb.de> X-Provags-ID: V02:K0:txarRBwDUwlWhEmjTg5xZANYLAKvyzmrFS2iqGiuEwP GSQrpKcRxAnM5Twq3j5Xzd9pLcq8ZCnj5+4Xuov3kd/iZrWS3W CIvwWH80Iz7J7X3OkiGZ1B5zoxOTp/yN2sKDlenhKWTd9FhENq QCw0gupqkopAEyhKMWY5V0KTv4xDyEwcHT8vhjNfo6OhSxjKCi Oo1p+zkau20BZzTqZ9nNQ== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This removes the BKL in hpfs in a rather awful way, by replacing it with a mutex that basically serializes the entire file system. The only reason I hope to get away with this is because there don't seem to be any real users left, and the file system is going out through the staging door anyways. Since the mutex code is not even tested and I don't expect anyone to do that, I'm marking it as broken on SMP and PREEMPT kernels, so it won't actually get used. Signed-off-by: Arnd Bergmann Cc: Mikulas Patocka Cc: linux-fsdevel@vger.kernel.org --- fs/hpfs/Kconfig | 2 +- fs/hpfs/hpfs_fn.h | 30 ++++++++++++++++++++++++++---- fs/hpfs/super.c | 1 + 3 files changed, 28 insertions(+), 5 deletions(-) diff --git a/fs/hpfs/Kconfig b/fs/hpfs/Kconfig index 63b6f56..73476c1 100644 --- a/fs/hpfs/Kconfig +++ b/fs/hpfs/Kconfig @@ -1,7 +1,7 @@ config HPFS_FS tristate "OS/2 HPFS file system support" depends on BLOCK - depends on BKL # nontrivial to fix + depends on BROKEN || !(SMP || PREEMPT) help OS/2 is IBM's operating system for PC's, the same as Warp, and HPFS is the file system used for organizing files on OS/2 hard disk diff --git a/fs/hpfs/hpfs_fn.h b/fs/hpfs/hpfs_fn.h index 6761cb3..ffdb16e 100644 --- a/fs/hpfs/hpfs_fn.h +++ b/fs/hpfs/hpfs_fn.h @@ -13,7 +13,6 @@ #include #include #include -#include #include "hpfs.h" @@ -90,6 +89,7 @@ struct hpfs_sb_info { unsigned sb_max_fwd_alloc; /* max forwad allocation */ struct mutex hpfs_creation_de; /* when creating dirents, nobody else can alloc blocks */ + struct mutex global_mutex; /* replaces BKL, serializes everything on SMP */ /*unsigned sb_mounting : 1;*/ int sb_timeshift; }; @@ -345,14 +345,36 @@ static inline time32_t gmt_to_local(struct super_block *s, time_t t) } /* - * Locking + * Locking: + * + * hpfs_lock() is a leftover from the big kernel lock. + * This mutex is used as the outermost lock in hpfs, + * all other mutexes (inode->i_mutex, hpfs_inode_info->i_mutex, + * hpfs_inode_info->i_parent_mutex, hpfs_creation_de and + * lock_super) can get taken while hpfs_lock is held already. + * + * Code inspection has shown that hpfs_lock never gets taken + * recursively, and that it never nests inside one of the + * mutexes above, so there should be no deadlocks. + * + * However, it is frequently held while wait_for_buffer + * sleeps, which probably causes a huge slowdown, since + * that serializes all operations on a file system. + * + * Moreover, the locking code is entirely untested, use at + * your own risk. */ static inline void hpfs_lock(struct super_block *s) { - lock_kernel(); +#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) +#warning HPFS is likely broken on SMP configurations + mutex_lock(&hpfs_sb(s)->global_mutex); +#endif } static inline void hpfs_unlock(struct super_block *s) { - unlock_kernel(); +#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) + mutex_unlock(&hpfs_sb(s)->global_mutex); +#endif } diff --git a/fs/hpfs/super.c b/fs/hpfs/super.c index 501ea86..694a683 100644 --- a/fs/hpfs/super.c +++ b/fs/hpfs/super.c @@ -491,6 +491,7 @@ static int hpfs_fill_super(struct super_block *s, void *options, int silent) sbi->sb_cp_table = NULL; mutex_init(&sbi->hpfs_creation_de); + mutex_init(&sbi->global_mutex); uid = current_uid(); gid = current_gid(); -- 1.7.1