From: Jan Kara <jack@suse.cz>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org, Jan Kara <jack@suse.com>
Subject: Re: [PATCH v4 03/12] ext2, dax: finish implementing dax_sem helpers
Date: Tue, 27 Feb 2018 18:00:31 +0100 [thread overview]
Message-ID: <20180227170031.lgf5tc3vt3umrwbb@quack2.suse.cz> (raw)
In-Reply-To: <151970521121.26729.7741760690622342144.stgit@dwillia2-desk3.amr.corp.intel.com>
On Mon 26-02-18 20:20:11, Dan Williams wrote:
> dax_sem_{up,down}_write_sem() allow the ext2 dax semaphore to be compiled
> out in the CONFIG_FS_DAX=n case. However there are still some open coded
> uses of the semaphore. Add dax_sem_{up_read,down_read,_is_locked}()
> helpers and convert all open-coded usages of the semaphore to the
> helpers.
Just one nit below. With that fixed you can add:
Reviewed-by: Jan Kara <jack@suse.cz>
> Cc: Jan Kara <jack@suse.com>
> Cc: <stable@vger.kernel.org>
> Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap")
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> fs/ext2/ext2.h | 6 ++++++
> fs/ext2/file.c | 5 ++---
> fs/ext2/inode.c | 4 +---
> 3 files changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
> index 032295e1d386..7ceb29733cdb 100644
> --- a/fs/ext2/ext2.h
> +++ b/fs/ext2/ext2.h
> @@ -711,9 +711,15 @@ struct ext2_inode_info {
> #ifdef CONFIG_FS_DAX
> #define dax_sem_down_write(ext2_inode) down_write(&(ext2_inode)->dax_sem)
> #define dax_sem_up_write(ext2_inode) up_write(&(ext2_inode)->dax_sem)
> +#define dax_sem_is_locked(ext2_inode) rwsem_is_locked(&(ext2_inode)->dax_sem)
> +#define dax_sem_down_read(ext2_inode) down_read(&(ext2_inode)->dax_sem)
> +#define dax_sem_up_read(ext2_inode) up_read(&(ext2_inode)->dax_sem)
> #else
> #define dax_sem_down_write(ext2_inode)
> #define dax_sem_up_write(ext2_inode)
> +#define dax_sem_is_locked(ext2_inode) (true)
This is a bit dangerous as depending on the use of dax_sem_is_locked()
you'd need this to return true or false. E.g. assume we'd have a place
where we'd like to do:
WARN_ON(dax_sem_is_locked(inode));
or just
if (dax_sem_is_locked(inode))
bail out due to congestion...
How I'd solve this is that I'd define:
#define assert_dax_sem_locked(ext2_inode) WARN_ON(rwsem_is_locked(&(ext2_inode)->dax_sem)
and just as do {} while (0) for !CONFIG_FS_DAX.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2018-02-27 17:00 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-27 4:19 [PATCH v4 00/12] vfio, dax: prevent long term filesystem-dax pins and other fixes Dan Williams
2018-02-27 4:20 ` [PATCH v4 01/12] dax: fix vma_is_fsdax() helper Dan Williams
2018-02-27 4:20 ` [PATCH v4 02/12] dax: introduce IS_DEVDAX() and IS_FSDAX() Dan Williams
2018-02-27 16:54 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 03/12] ext2, dax: finish implementing dax_sem helpers Dan Williams
2018-02-27 17:00 ` Jan Kara [this message]
2018-02-27 4:20 ` [PATCH v4 04/12] ext2, dax: define ext2_dax_*() infrastructure in all cases Dan Williams
2018-02-27 17:01 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 05/12] ext4, dax: define ext4_dax_*() " Dan Williams
2018-02-27 17:01 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 06/12] ext2, dax: replace IS_DAX() with IS_FSDAX() Dan Williams
2018-02-27 17:02 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 07/12] ext4, " Dan Williams
2018-02-27 17:02 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 08/12] xfs, " Dan Williams
2018-02-27 17:03 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 09/12] mm, dax: replace IS_DAX() with IS_DEVDAX() or IS_FSDAX() Dan Williams
2018-02-27 17:05 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 10/12] fs, dax: kill IS_DAX() Dan Williams
2018-02-27 17:06 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 11/12] dax: fix S_DAX definition Dan Williams
2018-02-27 4:20 ` [PATCH v4 12/12] vfio: disable filesystem-dax page pinning Dan Williams
2018-02-27 22:23 ` [PATCH v4 00/12] vfio, dax: prevent long term filesystem-dax pins and other fixes Dave Chinner
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