On Thu 16-08-12 12:00:26, Marco Stornelli wrote:
> From: Marco Stornelli <[email protected]>
> 
> Replaced lock and unlock super with a new fs mutex s_lock.
  Hum, is the lock needed at all? Remount & unfreeze both run with s_umount
held for writing. Thus we already have exclusion between these two calls.
The same seems to hold for ext4 BTW.

                                                                Honza
> 
> Signed-off-by: Marco Stornelli <[email protected]>
> ---
> 
> diff -Nurp linux-3.6-rc1-orig/fs/ext3/ext3.h linux-3.6-rc1/fs/ext3/ext3.h
> --- linux-3.6-rc1-orig/fs/ext3/ext3.h 2012-08-16 09:37:31.000000000 +0200
> +++ linux-3.6-rc1/fs/ext3/ext3.h      2012-08-16 09:46:39.000000000 +0200
> @@ -672,6 +672,7 @@ struct ext3_sb_info {
>       char *s_qf_names[MAXQUOTAS];            /* Names of quota files with 
> journalled quota */
>       int s_jquota_fmt;                       /* Format of quota to use */
>  #endif
> +     struct mutex s_lock;
>  };
>   static inline spinlock_t *
> diff -Nurp linux-3.6-rc1-orig/fs/ext3/super.c linux-3.6-rc1/fs/ext3/super.c
> --- linux-3.6-rc1-orig/fs/ext3/super.c        2012-08-16 09:37:31.000000000 
> +0200
> +++ linux-3.6-rc1/fs/ext3/super.c     2012-08-16 09:49:11.000000000 +0200
> @@ -1939,6 +1939,7 @@ static int ext3_fill_super (struct super
>       sbi->s_gdb_count = db_count;
>       get_random_bytes(&sbi->s_next_generation, sizeof(u32));
>       spin_lock_init(&sbi->s_next_gen_lock);
> +     mutex_init(&sbi->s_lock);
>       /* per fileystem reservation list head & lock */
>       spin_lock_init(&sbi->s_rsv_window_lock);
> @@ -2582,11 +2583,11 @@ out:
>  static int ext3_unfreeze(struct super_block *sb)
>  {
>       if (!(sb->s_flags & MS_RDONLY)) {
> -             lock_super(sb);
> +             mutex_lock(&EXT3_SB(sb)->s_lock);
>               /* Reser the needs_recovery flag before the fs is unlocked. */
>               EXT3_SET_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_RECOVER);
>               ext3_commit_super(sb, EXT3_SB(sb)->s_es, 1);
> -             unlock_super(sb);
> +             mutex_unlock(&EXT3_SB(sb)->s_lock);
>               journal_unlock_updates(EXT3_SB(sb)->s_journal);
>       }
>       return 0;
> @@ -2606,7 +2607,7 @@ static int ext3_remount (struct super_bl
>  #endif
>       /* Store the original options */
> -     lock_super(sb);
> +     mutex_lock(&EXT3_SB(sb)->s_lock);
>       old_sb_flags = sb->s_flags;
>       old_opts.s_mount_opt = sbi->s_mount_opt;
>       old_opts.s_resuid = sbi->s_resuid;
> @@ -2712,7 +2713,7 @@ static int ext3_remount (struct super_bl
>                   old_opts.s_qf_names[i] != sbi->s_qf_names[i])
>                       kfree(old_opts.s_qf_names[i]);
>  #endif
> -     unlock_super(sb);
> +     mutex_unlock(&EXT3_SB(sb)->s_lock);
>       if (enable_quota)
>               dquot_resume(sb, -1);
> @@ -2732,7 +2733,7 @@ restore_opts:
>               sbi->s_qf_names[i] = old_opts.s_qf_names[i];
>       }
>  #endif
> -     unlock_super(sb);
> +     mutex_unlock(&EXT3_SB(sb)->s_lock);
>       return err;
>  }
>  
-- 
Jan Kara <[email protected]>
SUSE Labs, CR
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