Linux-Fsdevel Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Shiyang Ruan <ruansy.fnst@cn.fujitsu.com>
To: <linux-kernel@vger.kernel.org>, <linux-xfs@vger.kernel.org>,
	<linux-nvdimm@lists.01.org>
Cc: <linux-mm@kvack.org>, <linux-fsdevel@vger.kernel.org>,
	<darrick.wong@oracle.com>, <dan.j.williams@intel.com>,
	<david@fromorbit.com>, <hch@lst.de>, <rgoldwyn@suse.de>,
	<qi.fuli@fujitsu.com>, <y-goto@fujitsu.com>
Subject: [RFC PATCH 1/8] fs: introduce get_shared_files() for dax&reflink
Date: Fri, 7 Aug 2020 21:13:29 +0800	[thread overview]
Message-ID: <20200807131336.318774-2-ruansy.fnst@cn.fujitsu.com> (raw)
In-Reply-To: <20200807131336.318774-1-ruansy.fnst@cn.fujitsu.com>

Under the mode of both dax and reflink on, one page may be shared by
multiple files and offsets.  In order to track them in memory-failure or
other cases, we introduce this function by finding out who is sharing
this block(the page) in a filesystem.  It returns a list that contains
all the owners, and the offset in each owner.

For XFS, rmapbt is used to find out the owners of one block.  So, it
should be turned on when we want to use dax&reflink feature together.

Signed-off-by: Shiyang Ruan <ruansy.fnst@cn.fujitsu.com>
---
 fs/xfs/xfs_super.c  | 67 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/dax.h |  7 +++++
 include/linux/fs.h  |  2 ++
 3 files changed, 76 insertions(+)

diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 379cbff438bc..b71392219c91 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -35,6 +35,9 @@
 #include "xfs_refcount_item.h"
 #include "xfs_bmap_item.h"
 #include "xfs_reflink.h"
+#include "xfs_alloc.h"
+#include "xfs_rmap.h"
+#include "xfs_rmap_btree.h"
 
 #include <linux/magic.h>
 #include <linux/fs_context.h>
@@ -1097,6 +1100,69 @@ xfs_fs_free_cached_objects(
 	return xfs_reclaim_inodes_nr(XFS_M(sb), sc->nr_to_scan);
 }
 
+static int _get_shared_files_fn(
+	struct xfs_btree_cur	*cur,
+	struct xfs_rmap_irec	*rec,
+	void			*priv)
+{
+	struct list_head	*list = priv;
+	struct xfs_inode	*ip;
+	struct shared_files	*sfp;
+
+	/* Get files that incore, filter out others that are not in use. */
+	xfs_iget(cur->bc_mp, cur->bc_tp, rec->rm_owner, XFS_IGET_INCORE, 0, &ip);
+	if (ip && !ip->i_vnode.i_mapping)
+		return 0;
+
+	sfp = kmalloc(sizeof(*sfp), GFP_KERNEL);
+	sfp->mapping = ip->i_vnode.i_mapping;
+	sfp->index = rec->rm_offset;
+	list_add_tail(&sfp->list, list);
+
+	return 0;
+}
+
+static int
+xfs_fs_get_shared_files(
+	struct super_block	*sb,
+	pgoff_t			offset,
+	struct list_head	*list)
+{
+	struct xfs_mount	*mp = XFS_M(sb);
+	struct xfs_trans	*tp = NULL;
+	struct xfs_btree_cur	*cur = NULL;
+	struct xfs_rmap_irec	rmap_low = { 0 }, rmap_high = { 0 };
+	struct xfs_buf		*agf_bp = NULL;
+	xfs_agblock_t		bno = XFS_B_TO_FSB(mp, offset);
+	xfs_agnumber_t		agno = XFS_FSB_TO_AGNO(mp, bno);
+	int			error = 0;
+
+	error = xfs_trans_alloc_empty(mp, &tp);
+	if (error)
+		return error;
+
+	error = xfs_alloc_read_agf(mp, tp, agno, 0, &agf_bp);
+	if (error)
+		return error;
+
+	cur = xfs_rmapbt_init_cursor(mp, tp, agf_bp, agno);
+
+	memset(&cur->bc_rec, 0, sizeof(cur->bc_rec));
+	/* Construct the range for one rmap search */
+	memset(&rmap_low, 0, sizeof(rmap_low));
+	memset(&rmap_high, 0xFF, sizeof(rmap_high));
+	rmap_low.rm_startblock = rmap_high.rm_startblock = bno;
+
+	error = xfs_rmap_query_range(cur, &rmap_low, &rmap_high,
+				     _get_shared_files_fn, list);
+	if (error == -ECANCELED)
+		error = 0;
+
+	xfs_btree_del_cursor(cur, error);
+	xfs_trans_brelse(tp, agf_bp);
+	return error;
+}
+
 static const struct super_operations xfs_super_operations = {
 	.alloc_inode		= xfs_fs_alloc_inode,
 	.destroy_inode		= xfs_fs_destroy_inode,
@@ -1110,6 +1176,7 @@ static const struct super_operations xfs_super_operations = {
 	.show_options		= xfs_fs_show_options,
 	.nr_cached_objects	= xfs_fs_nr_cached_objects,
 	.free_cached_objects	= xfs_fs_free_cached_objects,
+	.get_shared_files	= xfs_fs_get_shared_files,
 };
 
 static int
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 6904d4e0b2e0..0a85e321d6b4 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -40,6 +40,13 @@ struct dax_operations {
 
 extern struct attribute_group dax_attribute_group;
 
+struct shared_files {
+	struct list_head	list;
+	struct address_space	*mapping;
+	pgoff_t			index;
+	dax_entry_t		cookie;
+};
+
 #if IS_ENABLED(CONFIG_DAX)
 struct dax_device *dax_get_by_host(const char *host);
 struct dax_device *alloc_dax(void *private, const char *host,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f5abba86107d..81de3d2739b9 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1977,6 +1977,8 @@ struct super_operations {
 				  struct shrink_control *);
 	long (*free_cached_objects)(struct super_block *,
 				    struct shrink_control *);
+	int (*get_shared_files)(struct super_block *sb, pgoff_t offset,
+				struct list_head *list);
 };
 
 /*
-- 
2.27.0




  reply	other threads:[~2020-08-07 13:13 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-07 13:13 [RFC PATCH 0/8] fsdax: introduce FS query interface to support reflink Shiyang Ruan
2020-08-07 13:13 ` Shiyang Ruan [this message]
2020-08-07 16:15   ` [RFC PATCH 1/8] fs: introduce get_shared_files() for dax&reflink Darrick J. Wong
2020-08-10  8:07     ` Ruan Shiyang
2020-08-07 13:13 ` [RFC PATCH 2/8] fsdax, mm: track files sharing dax page for memory-failure Shiyang Ruan
2020-08-07 13:13 ` [RFC PATCH 3/8] fsdax: introduce dax_copy_edges() for COW Shiyang Ruan
2020-08-07 13:13 ` [RFC PATCH 4/8] fsdax: copy data before write Shiyang Ruan
2020-08-07 13:13 ` [RFC PATCH 5/8] fsdax: replace mmap entry in case of CoW Shiyang Ruan
2020-08-07 13:13 ` [RFC PATCH 6/8] fsdax: dedup file range to use a compare function Shiyang Ruan
2020-08-07 13:13 ` [RFC PATCH 7/8] fs/xfs: handle CoW for fsdax write() path Shiyang Ruan
2020-08-07 13:13 ` [RFC PATCH 8/8] fs/xfs: support dedupe for fsdax Shiyang Ruan
2020-08-07 13:38 ` [RFC PATCH 0/8] fsdax: introduce FS query interface to support reflink Matthew Wilcox
2020-08-10  8:15   ` Ruan Shiyang
2020-08-10 11:16     ` Matthew Wilcox
2020-08-10 21:10       ` Dave Chinner

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=20200807131336.318774-2-ruansy.fnst@cn.fujitsu.com \
    --to=ruansy.fnst@cn.fujitsu.com \
    --cc=dan.j.williams@intel.com \
    --cc=darrick.wong@oracle.com \
    --cc=david@fromorbit.com \
    --cc=hch@lst.de \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-nvdimm@lists.01.org \
    --cc=linux-xfs@vger.kernel.org \
    --cc=qi.fuli@fujitsu.com \
    --cc=rgoldwyn@suse.de \
    --cc=y-goto@fujitsu.com \
    --subject='Re: [RFC PATCH 1/8] fs: introduce get_shared_files() for dax&reflink' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).