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Message-ID: <20171130165948.GF28180@quack2.suse.cz>
Date: Thu, 30 Nov 2017 17:59:48 +0100
From: Jan Kara <jack@...e.cz>
To: "Luis R. Rodriguez" <mcgrof@...nel.org>
Cc: viro@...iv.linux.org.uk, bart.vanassche@....com,
ming.lei@...hat.com, tytso@....edu, darrick.wong@...cle.com,
jikos@...nel.org, rjw@...ysocki.net, pavel@....cz,
len.brown@...el.com, linux-fsdevel@...r.kernel.org,
boris.ostrovsky@...cle.com, jgross@...e.com,
todd.e.brandt@...ux.intel.com, nborisov@...e.com, jack@...e.cz,
martin.petersen@...cle.com, ONeukum@...e.com,
oleksandr@...alenko.name, oleg.b.antonyan@...il.com,
yu.chen.surf@...il.com, dan.j.williams@...el.com,
linux-pm@...r.kernel.org, linux-block@...r.kernel.org,
linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 02/11] fs: provide unlocked helper thaw_super()
On Wed 29-11-17 15:23:47, Luis R. Rodriguez wrote:
> thaw_super() hold a write lock, however we wish to also enable
> callers which already hold the write lock. To do this provide a helper
> and make thaw_super() use it. This way, all that thaw_super() does
> now is lock handling and active count management.
>
> This change has no functional changes.
>
> Suggested-by: Dave Chinner <david@...morbit.com>
> Signed-off-by: Luis R. Rodriguez <mcgrof@...nel.org>
Looks good to me. You can add:
Reviewed-by: Jan Kara <jack@...e.cz>
Honza
> ---
> fs/super.c | 39 ++++++++++++++++++++++++++-------------
> 1 file changed, 26 insertions(+), 13 deletions(-)
>
> diff --git a/fs/super.c b/fs/super.c
> index a7650ff22f0e..cecc279beecd 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -1493,21 +1493,13 @@ int freeze_super(struct super_block *sb)
> }
> EXPORT_SYMBOL(freeze_super);
>
> -/**
> - * thaw_super -- unlock filesystem
> - * @sb: the super to thaw
> - *
> - * Unlocks the filesystem and marks it writeable again after freeze_super().
> - */
> -int thaw_super(struct super_block *sb)
> +/* Caller takes lock and handles active count */
> +static int thaw_locked_super(struct super_block *sb)
> {
> int error;
>
> - down_write(&sb->s_umount);
> - if (sb->s_writers.frozen != SB_FREEZE_COMPLETE) {
> - up_write(&sb->s_umount);
> + if (sb->s_writers.frozen != SB_FREEZE_COMPLETE)
> return -EINVAL;
> - }
>
> if (sb_rdonly(sb)) {
> sb->s_writers.frozen = SB_UNFROZEN;
> @@ -1522,7 +1514,6 @@ int thaw_super(struct super_block *sb)
> printk(KERN_ERR
> "VFS:Filesystem thaw failed\n");
> lockdep_sb_freeze_release(sb);
> - up_write(&sb->s_umount);
> return error;
> }
> }
> @@ -1531,7 +1522,29 @@ int thaw_super(struct super_block *sb)
> sb_freeze_unlock(sb);
> out:
> wake_up(&sb->s_writers.wait_unfrozen);
> - deactivate_locked_super(sb);
> return 0;
> }
> +
> +/**
> + * thaw_super -- unlock filesystem
> + * @sb: the super to thaw
> + *
> + * Unlocks the filesystem and marks it writeable again after freeze_super().
> + */
> +int thaw_super(struct super_block *sb)
> +{
> + int error;
> +
> + down_write(&sb->s_umount);
> + error = thaw_locked_super(sb);
> + if (error) {
> + up_write(&sb->s_umount);
> + goto out;
> + }
> +
> + deactivate_locked_super(sb);
> +
> +out:
> + return error;
> +}
> EXPORT_SYMBOL(thaw_super);
> --
> 2.15.0
>
--
Jan Kara <jack@...e.com>
SUSE Labs, CR
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