From: "Darrick J. Wong" <djwong@kernel.org>
To: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Cc: linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org,
linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org,
darrick.wong@oracle.com, dan.j.williams@intel.com,
willy@infradead.org, viro@zeniv.linux.org.uk,
david@fromorbit.com, hch@lst.de, rgoldwyn@suse.de, jack@suse.cz
Subject: Re: [PATCH v6 7/7] fs/xfs: Add dax dedupe support
Date: Tue, 25 May 2021 17:31:16 -0700 [thread overview]
Message-ID: <20210526003116.GU202121@locust> (raw)
In-Reply-To: <20210519060045.1051226-8-ruansy.fnst@fujitsu.com>
On Wed, May 19, 2021 at 02:00:45PM +0800, Shiyang Ruan wrote:
> Introduce xfs_mmaplock_two_inodes_and_break_dax_layout() for dax files
> who are going to be deduped. After that, call compare range function
> only when files are both DAX or not.
>
> Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
> ---
> fs/xfs/xfs_file.c | 2 +-
> fs/xfs/xfs_inode.c | 57 ++++++++++++++++++++++++++++++++++++++++++++
> fs/xfs/xfs_inode.h | 1 +
> fs/xfs/xfs_reflink.c | 4 ++--
> 4 files changed, 61 insertions(+), 3 deletions(-)
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 38d8eca05aee..bd5002d38df4 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -823,7 +823,7 @@ xfs_wait_dax_page(
> xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
> }
>
> -static int
> +int
> xfs_break_dax_layouts(
> struct inode *inode,
> bool *retry)
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 0369eb22c1bb..d5e2791969ba 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -3711,6 +3711,59 @@ xfs_iolock_two_inodes_and_break_layout(
> return 0;
> }
>
> +static int
> +xfs_mmaplock_two_inodes_and_break_dax_layout(
> + struct xfs_inode *ip1,
> + struct xfs_inode *ip2)
> +{
> + int error, attempts = 0;
> + bool retry;
> + struct page *page;
> + struct xfs_log_item *lp;
> +
> + if (ip1->i_ino > ip2->i_ino)
> + swap(ip1, ip2);
If Jan Kara [added to cc] succeeds in hoisting the MMAPLOCK to struct
address space then this is going to have to change to:
if (VFS_I(ip1)->i_mapping > VFS_I(ip2)->i_mapping)
swap(ip1, ip2);
For now this is ok.
> +
> +again:
> + retry = false;
> + /* Lock the first inode */
> + xfs_ilock(ip1, XFS_MMAPLOCK_EXCL);
> + error = xfs_break_dax_layouts(VFS_I(ip1), &retry);
> + if (error || retry) {
> + xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL);
> + goto again;
> + }
> +
> + if (ip1 == ip2)
> + return 0;
> +
> + /* Nested lock the second inode */
> + lp = &ip1->i_itemp->ili_item;
> + if (lp && test_bit(XFS_LI_IN_AIL, &lp->li_flags)) {
> + if (!xfs_ilock_nowait(ip2,
> + xfs_lock_inumorder(XFS_MMAPLOCK_EXCL, 1))) {
> + xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL);
> + if ((++attempts % 5) == 0)
> + delay(1); /* Don't just spin the CPU */
> + goto again;
> + }
> + } else
> + xfs_ilock(ip2, xfs_lock_inumorder(XFS_MMAPLOCK_EXCL, 1));
I wonder if this chunk is really necessary considering that the AIL
never touches the MMAPLOCK/i_mapping invalidation lock? I guess it
doesn't really hurt anything since that's what the code does now.
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
--D
> + /*
> + * We cannot use xfs_break_dax_layouts() directly here because it may
> + * need to unlock & lock the XFS_MMAPLOCK_EXCL which is not suitable
> + * for this nested lock case.
> + */
> + page = dax_layout_busy_page(VFS_I(ip2)->i_mapping);
> + if (page && page_ref_count(page) != 1) {
> + xfs_iunlock(ip2, XFS_MMAPLOCK_EXCL);
> + xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL);
> + goto again;
> + }
> +
> + return 0;
> +}
> +
> /*
> * Lock two inodes so that userspace cannot initiate I/O via file syscalls or
> * mmap activity.
> @@ -3725,6 +3778,10 @@ xfs_ilock2_io_mmap(
> ret = xfs_iolock_two_inodes_and_break_layout(VFS_I(ip1), VFS_I(ip2));
> if (ret)
> return ret;
> +
> + if (IS_DAX(VFS_I(ip1)) && IS_DAX(VFS_I(ip2)))
> + return xfs_mmaplock_two_inodes_and_break_dax_layout(ip1, ip2);
> +
> if (ip1 == ip2)
> xfs_ilock(ip1, XFS_MMAPLOCK_EXCL);
> else
> diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
> index ca826cfba91c..2d0b344fb100 100644
> --- a/fs/xfs/xfs_inode.h
> +++ b/fs/xfs/xfs_inode.h
> @@ -457,6 +457,7 @@ enum xfs_prealloc_flags {
>
> int xfs_update_prealloc_flags(struct xfs_inode *ip,
> enum xfs_prealloc_flags flags);
> +int xfs_break_dax_layouts(struct inode *inode, bool *retry);
> int xfs_break_layouts(struct inode *inode, uint *iolock,
> enum layout_break_reason reason);
>
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index 9a780948dbd0..ff308304c5cd 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -1324,8 +1324,8 @@ xfs_reflink_remap_prep(
> if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest))
> goto out_unlock;
>
> - /* Don't share DAX file data for now. */
> - if (IS_DAX(inode_in) || IS_DAX(inode_out))
> + /* Don't share DAX file data with non-DAX file. */
> + if (IS_DAX(inode_in) != IS_DAX(inode_out))
> goto out_unlock;
>
> if (!IS_DAX(inode_in))
> --
> 2.31.1
>
>
>
next prev parent reply other threads:[~2021-05-26 0:31 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-19 6:00 [PATCH v6 0/7] fsdax,xfs: Add reflink&dedupe support for fsdax Shiyang Ruan
2021-05-19 6:00 ` [PATCH v6 1/7] fsdax: Introduce dax_iomap_cow_copy() Shiyang Ruan
2021-05-19 6:00 ` [PATCH v6 2/7] fsdax: Replace mmap entry in case of CoW Shiyang Ruan
2021-05-19 6:00 ` [PATCH v6 3/7] fsdax: Add dax_iomap_cow_copy() for dax_iomap_zero Shiyang Ruan
2021-05-25 22:17 ` Darrick J. Wong
2021-05-19 6:00 ` [PATCH v6 4/7] iomap: Introduce iomap_apply2() for operations on two files Shiyang Ruan
2021-05-19 6:00 ` [PATCH v6 5/7] fsdax: Dedup file range to use a compare function Shiyang Ruan
2021-05-25 23:29 ` Darrick J. Wong
2021-05-19 6:00 ` [PATCH v6 6/7] fs/xfs: Handle CoW for fsdax write() path Shiyang Ruan
2021-05-26 0:21 ` Darrick J. Wong
2021-06-09 2:28 ` ruansy.fnst
2021-06-15 7:21 ` [PATCH v6.1 " Shiyang Ruan
2021-06-24 8:49 ` ruansy.fnst
2021-06-25 22:18 ` Darrick J. Wong
2021-06-28 2:55 ` ruansy.fnst
2021-06-28 5:09 ` Darrick J. Wong
2021-06-29 11:25 ` ruansy.fnst
2021-06-29 21:01 ` Darrick J. Wong
2021-07-08 23:16 ` Dave Chinner
2021-07-09 12:36 ` [PATCH v6.2 6/7] dax: Introduce dax_iomap_ops for end of reflink Shiyang Ruan
2021-05-19 6:00 ` [PATCH v6 7/7] fs/xfs: Add dax dedupe support Shiyang Ruan
2021-05-26 0:31 ` Darrick J. Wong [this message]
2021-05-26 0:51 ` [PATCH v6 0/7] fsdax,xfs: Add reflink&dedupe support for fsdax Darrick J. Wong
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