Linux-Fsdevel Archive on lore.kernel.org
 help / color / Atom feed
From: Jan Kara <jack@suse.cz>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: linux-fsdevel@vger.kernel.org, dan.j.williams@intel.com,
	jack@suse.cz, willy@infradead.org, virtio-fs@redhat.com,
	slp@redhat.com, miklos@szeredi.hu, linux-nvdimm@lists.01.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/3] dax: Add an enum for specifying dax wakup mode
Date: Wed, 21 Apr 2021 11:24:40 +0200
Message-ID: <20210421092440.GM8706@quack2.suse.cz> (raw)
In-Reply-To: <20210419213636.1514816-2-vgoyal@redhat.com>

On Mon 19-04-21 17:36:34, Vivek Goyal wrote:
> Dan mentioned that he is not very fond of passing around a boolean true/false
> to specify if only next waiter should be woken up or all waiters should be
> woken up. He instead prefers that we introduce an enum and make it very
> explicity at the callsite itself. Easier to read code.
> 
> This patch should not introduce any change of behavior.
> 
> Suggested-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> ---
>  fs/dax.c | 23 +++++++++++++++++------
>  1 file changed, 17 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index b3d27fdc6775..00978d0838b1 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -144,6 +144,16 @@ struct wait_exceptional_entry_queue {
>  	struct exceptional_entry_key key;
>  };
>  
> +/**
> + * enum dax_entry_wake_mode: waitqueue wakeup toggle
> + * @WAKE_NEXT: entry was not mutated
> + * @WAKE_ALL: entry was invalidated, or resized

Let's document the constants in terms of what they do, not when they are
expected to be called. So something like:

@WAKE_NEXT: wake only the first waiter in the waitqueue
@WAKE_ALL: wake all waiters in the waitqueue

Otherwise the patch looks good so feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> + */
> +enum dax_entry_wake_mode {
> +	WAKE_NEXT,
> +	WAKE_ALL,
> +};
> +
>  static wait_queue_head_t *dax_entry_waitqueue(struct xa_state *xas,
>  		void *entry, struct exceptional_entry_key *key)
>  {
> @@ -182,7 +192,8 @@ static int wake_exceptional_entry_func(wait_queue_entry_t *wait,
>   * The important information it's conveying is whether the entry at
>   * this index used to be a PMD entry.
>   */
> -static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all)
> +static void dax_wake_entry(struct xa_state *xas, void *entry,
> +			   enum dax_entry_wake_mode mode)
>  {
>  	struct exceptional_entry_key key;
>  	wait_queue_head_t *wq;
> @@ -196,7 +207,7 @@ static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all)
>  	 * must be in the waitqueue and the following check will see them.
>  	 */
>  	if (waitqueue_active(wq))
> -		__wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
> +		__wake_up(wq, TASK_NORMAL, mode == WAKE_ALL ? 0 : 1, &key);
>  }
>  
>  /*
> @@ -268,7 +279,7 @@ static void put_unlocked_entry(struct xa_state *xas, void *entry)
>  {
>  	/* If we were the only waiter woken, wake the next one */
>  	if (entry && !dax_is_conflict(entry))
> -		dax_wake_entry(xas, entry, false);
> +		dax_wake_entry(xas, entry, WAKE_NEXT);
>  }
>  
>  /*
> @@ -286,7 +297,7 @@ static void dax_unlock_entry(struct xa_state *xas, void *entry)
>  	old = xas_store(xas, entry);
>  	xas_unlock_irq(xas);
>  	BUG_ON(!dax_is_locked(old));
> -	dax_wake_entry(xas, entry, false);
> +	dax_wake_entry(xas, entry, WAKE_NEXT);
>  }
>  
>  /*
> @@ -524,7 +535,7 @@ static void *grab_mapping_entry(struct xa_state *xas,
>  
>  		dax_disassociate_entry(entry, mapping, false);
>  		xas_store(xas, NULL);	/* undo the PMD join */
> -		dax_wake_entry(xas, entry, true);
> +		dax_wake_entry(xas, entry, WAKE_ALL);
>  		mapping->nrexceptional--;
>  		entry = NULL;
>  		xas_set(xas, index);
> @@ -937,7 +948,7 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev,
>  	xas_lock_irq(xas);
>  	xas_store(xas, entry);
>  	xas_clear_mark(xas, PAGECACHE_TAG_DIRTY);
> -	dax_wake_entry(xas, entry, false);
> +	dax_wake_entry(xas, entry, WAKE_NEXT);
>  
>  	trace_dax_writeback_one(mapping->host, index, count);
>  	return ret;
> -- 
> 2.25.4
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

  parent reply index

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-19 21:36 [PATCH v3 0/3] dax: Fix missed wakeup in put_unlocked_entry() Vivek Goyal
2021-04-19 21:36 ` [PATCH v3 1/3] dax: Add an enum for specifying dax wakup mode Vivek Goyal
2021-04-20  7:19   ` [Virtio-fs] " Greg Kurz
2021-04-21  9:24   ` Jan Kara [this message]
2021-04-21 15:56     ` Vivek Goyal
2021-04-21 16:16       ` Matthew Wilcox
2021-04-21 17:21         ` Vivek Goyal
2021-04-19 21:36 ` [PATCH v3 2/3] dax: Add a wakeup mode parameter to put_unlocked_entry() Vivek Goyal
2021-04-20  7:34   ` [Virtio-fs] " Greg Kurz
2021-04-20 14:00     ` Vivek Goyal
2021-04-21 19:09       ` Dan Williams
2021-04-21 19:13         ` Vivek Goyal
2021-04-22  6:24         ` Christoph Hellwig
2021-04-22 16:12           ` Darrick J. Wong
2021-04-22 20:01           ` Dan Williams
2021-04-22 20:07             ` Vivek Goyal
2021-05-17 17:10           ` Dan Williams
2021-04-21 17:39     ` Vivek Goyal
2021-04-21  9:25   ` Jan Kara
2021-04-19 21:36 ` [PATCH v3 3/3] dax: Wake up all waiters after invalidating dax entry Vivek Goyal
2021-04-21  9:26   ` Jan Kara

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210421092440.GM8706@quack2.suse.cz \
    --to=jack@suse.cz \
    --cc=dan.j.williams@intel.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-nvdimm@lists.01.org \
    --cc=miklos@szeredi.hu \
    --cc=slp@redhat.com \
    --cc=vgoyal@redhat.com \
    --cc=virtio-fs@redhat.com \
    --cc=willy@infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Fsdevel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-fsdevel/0 linux-fsdevel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-fsdevel linux-fsdevel/ https://lore.kernel.org/linux-fsdevel \
		linux-fsdevel@vger.kernel.org
	public-inbox-index linux-fsdevel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-fsdevel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git