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Date: Wed, 14 Apr 2010 12:40:28 +0530
Message-ID: <o2r3f9a31f41004140010t7c553e39ib51e69fa9022a75f@mail.gmail.com>
Subject: Re: [PATCH 5/5] ext2: Add ext2_sb_info s_lock spinlock
From: Jaswinder Singh Rajput <jaswinderlinux@gmail.com>
To: Jan Blunck <jblunck@suse.de>
Cc: Jan Kara <jack@suse.cz>, tytso@mit.edu,
       Linux-Kernel Mailinglist <linux-kernel@vger.kernel.org>,
       linux-ext4@vger.kernel.org, Frederic Weisbecker <fweisbec@gmail.com>,
       Arnd Bergmann <arnd@arndb.de>, Andi Kleen <andi@firstfloor.org>,
       OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
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Hello,

On Tue, Apr 13, 2010 at 2:11 AM, Jan Blunck <jblunck@suse.de> wrote:
> Add a spinlock that protects against concurrent modifications of
> s_mount_state, s_blocks_last, s_overhead_last and the content of the
> superblock's buffer pointed to by sbi->s_es. This is a preparation patch
> for removing the BKL from ext2 in the next patch.
>
> Signed-off-by: Jan Blunck <jblunck@suse.de>
> Cc: Andi Kleen <andi@firstfloor.org>
> Cc: Jan Kara <jack@suse.cz>
> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
> ---
>  fs/ext2/inode.c            |    2 ++
>  fs/ext2/super.c            |   31 +++++++++++++++++++++++++++++--
>  include/linux/ext2_fs_sb.h |    6 ++++++
>  3 files changed, 37 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
> index fc13cc1..5d15442 100644
> --- a/fs/ext2/inode.c
> +++ b/fs/ext2/inode.c
> @@ -1407,9 +1407,11 @@ static int __ext2_write_inode(struct inode *inode, int do_sync)
>                                * created, add a flag to the superblock.
>                                */
>                                lock_kernel();
> +                               spin_lock(&EXT2_SB(sb)->s_lock);
>                                ext2_update_dynamic_rev(sb);
>                                EXT2_SET_RO_COMPAT_FEATURE(sb,
>                                        EXT2_FEATURE_RO_COMPAT_LARGE_FILE);
> +                               spin_unlock(&EXT2_SB(sb)->s_lock);
>                                unlock_kernel();
>                                ext2_write_super(sb);

Do we need both locks (kernel lock and spin lock)

Thanks,
--
JSR