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From:   Shiyang Ruan <ruansy.fnst@fujitsu.com>
To:     <linux-kernel@vger.kernel.org>, <linux-xfs@vger.kernel.org>,
        <nvdimm@lists.linux.dev>, <linux-mm@kvack.org>,
        <linux-fsdevel@vger.kernel.org>, <dm-devel@redhat.com>
CC:     <djwong@kernel.org>, <dan.j.williams@intel.com>,
        <david@fromorbit.com>, <hch@lst.de>, <agk@redhat.com>,
        <snitzer@redhat.com>
Subject: [PATCH RESEND v6 6/9] xfs: Implement ->notify_failure() for XFS
Date:   Fri, 30 Jul 2021 18:01:55 +0800
Message-ID: <20210730100158.3117319-7-ruansy.fnst@fujitsu.com>
In-Reply-To: <20210730100158.3117319-1-ruansy.fnst@fujitsu.com>
References: <20210730100158.3117319-1-ruansy.fnst@fujitsu.com>
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This function is used to handle errors which may cause data lost in
filesystem.  Such as memory failure in fsdax mode.

If the rmap feature of XFS enabled, we can query it to find files and
metadata which are associated with the corrupt data.  For now all we do
is kill processes with that file mapped into their address spaces, but
future patches could actually do something about corrupt metadata.

After that, the memory failure needs to notify the processes who are
using those files.

Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
---
 drivers/dax/super.c |  12 ++++
 fs/xfs/xfs_fsops.c  |   5 ++
 fs/xfs/xfs_mount.h  |   1 +
 fs/xfs/xfs_super.c  | 135 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/dax.h |  13 +++++
 5 files changed, 166 insertions(+)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 00c32dfa5665..63f7b63d078d 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -65,6 +65,18 @@ struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
 	return dax_get_by_host(bdev->bd_disk->disk_name);
 }
 EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
+
+void fs_dax_set_holder(struct dax_device *dax_dev, void *holder,
+		const struct dax_holder_operations *ops)
+{
+	dax_set_holder(dax_dev, holder, ops);
+}
+EXPORT_SYMBOL_GPL(fs_dax_set_holder);
+void *fs_dax_get_holder(struct dax_device *dax_dev)
+{
+	return dax_get_holder(dax_dev);
+}
+EXPORT_SYMBOL_GPL(fs_dax_get_holder);
 #endif
 
 bool __generic_fsdax_supported(struct dax_device *dax_dev,
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index 6ed29b158312..e96ddb5c28bc 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -549,6 +549,11 @@ xfs_do_force_shutdown(
 				flags, __return_address, fname, lnnum);
 		if (XFS_ERRLEVEL_HIGH <= xfs_error_level)
 			xfs_stack_trace();
+	} else if (flags & SHUTDOWN_CORRUPT_META) {
+		xfs_alert_tag(mp, XFS_PTAG_SHUTDOWN_CORRUPT,
+"Corruption of on-disk metadata detected.  Shutting down filesystem");
+		if (XFS_ERRLEVEL_HIGH <= xfs_error_level)
+			xfs_stack_trace();
 	} else if (logerror) {
 		xfs_alert_tag(mp, XFS_PTAG_SHUTDOWN_LOGERROR,
 "Log I/O error (0x%x) detected at %pS (%s:%d). Shutting down filesystem",
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index c78b63fe779a..203eb62d16d0 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -277,6 +277,7 @@ void xfs_do_force_shutdown(struct xfs_mount *mp, int flags, char *fname,
 #define SHUTDOWN_LOG_IO_ERROR	0x0002	/* write attempt to the log failed */
 #define SHUTDOWN_FORCE_UMOUNT	0x0004	/* shutdown from a forced unmount */
 #define SHUTDOWN_CORRUPT_INCORE	0x0008	/* corrupt in-memory data structures */
+#define SHUTDOWN_CORRUPT_META	0x0010  /* corrupt metadata on device */
 
 /*
  * Flags for xfs_mountfs
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 2c9e26a44546..4a362e14318d 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -37,11 +37,19 @@
 #include "xfs_reflink.h"
 #include "xfs_pwork.h"
 #include "xfs_ag.h"
+#include "xfs_alloc.h"
+#include "xfs_rmap.h"
+#include "xfs_rmap_btree.h"
+#include "xfs_rtalloc.h"
+#include "xfs_bit.h"
 
 #include <linux/magic.h>
 #include <linux/fs_context.h>
 #include <linux/fs_parser.h>
+#include <linux/mm.h>
+#include <linux/dax.h>
 
+static const struct dax_holder_operations xfs_dax_holder_operations;
 static const struct super_operations xfs_super_operations;
 
 static struct kset *xfs_kset;		/* top-level xfs sysfs dir */
@@ -352,6 +360,7 @@ xfs_close_devices(
 
 		xfs_free_buftarg(mp->m_logdev_targp);
 		xfs_blkdev_put(logdev);
+		fs_dax_set_holder(dax_logdev, NULL, NULL);
 		fs_put_dax(dax_logdev);
 	}
 	if (mp->m_rtdev_targp) {
@@ -360,9 +369,11 @@ xfs_close_devices(
 
 		xfs_free_buftarg(mp->m_rtdev_targp);
 		xfs_blkdev_put(rtdev);
+		fs_dax_set_holder(dax_rtdev, NULL, NULL);
 		fs_put_dax(dax_rtdev);
 	}
 	xfs_free_buftarg(mp->m_ddev_targp);
+	fs_dax_set_holder(dax_ddev, NULL, NULL);
 	fs_put_dax(dax_ddev);
 }
 
@@ -386,6 +397,7 @@ xfs_open_devices(
 	struct block_device	*logdev = NULL, *rtdev = NULL;
 	int			error;
 
+	fs_dax_set_holder(dax_ddev, mp, &xfs_dax_holder_operations);
 	/*
 	 * Open real time and log devices - order is important.
 	 */
@@ -394,6 +406,9 @@ xfs_open_devices(
 		if (error)
 			goto out;
 		dax_logdev = fs_dax_get_by_bdev(logdev);
+		if (dax_logdev != dax_ddev)
+			fs_dax_set_holder(dax_logdev, mp,
+				       &xfs_dax_holder_operations);
 	}
 
 	if (mp->m_rtname) {
@@ -408,6 +423,7 @@ xfs_open_devices(
 			goto out_close_rtdev;
 		}
 		dax_rtdev = fs_dax_get_by_bdev(rtdev);
+		fs_dax_set_holder(dax_rtdev, mp, &xfs_dax_holder_operations);
 	}
 
 	/*
@@ -1070,6 +1086,125 @@ xfs_fs_free_cached_objects(
 	return xfs_reclaim_inodes_nr(XFS_M(sb), sc->nr_to_scan);
 }
 
+static int
+xfs_corrupt_helper(
+	struct xfs_btree_cur		*cur,
+	struct xfs_rmap_irec		*rec,
+	void				*data)
+{
+	struct xfs_inode		*ip;
+	struct address_space		*mapping;
+	int				error = 0, *flags = data, i;
+
+	if (XFS_RMAP_NON_INODE_OWNER(rec->rm_owner) ||
+	    (rec->rm_flags & (XFS_RMAP_ATTR_FORK | XFS_RMAP_BMBT_BLOCK))) {
+		// TODO check and try to fix metadata
+		xfs_force_shutdown(cur->bc_mp, SHUTDOWN_CORRUPT_META);
+		return -EFSCORRUPTED;
+	}
+
+	/* Get files that incore, filter out others that are not in use. */
+	error = xfs_iget(cur->bc_mp, cur->bc_tp, rec->rm_owner, XFS_IGET_INCORE,
+			 0, &ip);
+	if (error)
+		return error;
+
+	mapping = VFS_I(ip)->i_mapping;
+	if (IS_ENABLED(CONFIG_MEMORY_FAILURE)) {
+		for (i = 0; i < rec->rm_blockcount; i++) {
+			error = mf_dax_kill_procs(mapping, rec->rm_offset + i,
+						  *flags);
+			if (error)
+				break;
+		}
+	}
+	// TODO try to fix data
+	xfs_irele(ip);
+
+	return error;
+}
+
+static loff_t
+xfs_dax_bdev_offset(
+	struct xfs_mount *mp,
+	struct dax_device *dax_dev,
+	loff_t disk_offset)
+{
+	struct block_device *bdev;
+
+	if (mp->m_ddev_targp->bt_daxdev == dax_dev)
+		bdev = mp->m_ddev_targp->bt_bdev;
+	else if (mp->m_logdev_targp->bt_daxdev == dax_dev)
+		bdev = mp->m_logdev_targp->bt_bdev;
+	else
+		bdev = mp->m_rtdev_targp->bt_bdev;
+
+	return disk_offset - (get_start_sect(bdev) << SECTOR_SHIFT);
+}
+
+static int
+xfs_dax_notify_failure(
+	struct dax_device	*dax_dev,
+	loff_t			offset,
+	size_t			len,
+	void			*data)
+{
+	struct xfs_mount	*mp = fs_dax_get_holder(dax_dev);
+	struct xfs_trans	*tp = NULL;
+	struct xfs_btree_cur	*cur = NULL;
+	struct xfs_buf		*agf_bp = NULL;
+	struct xfs_rmap_irec	rmap_low, rmap_high;
+	loff_t 			bdev_offset = xfs_dax_bdev_offset(mp, dax_dev,
+								  offset);
+	xfs_fsblock_t		fsbno = XFS_B_TO_FSB(mp, bdev_offset);
+	xfs_filblks_t		bcnt = XFS_B_TO_FSB(mp, len);
+	xfs_agnumber_t		agno = XFS_FSB_TO_AGNO(mp, fsbno);
+	xfs_agblock_t		agbno = XFS_FSB_TO_AGBNO(mp, fsbno);
+	int			error = 0;
+
+	if (mp->m_logdev_targp && mp->m_logdev_targp->bt_daxdev == dax_dev &&
+	    mp->m_logdev_targp != mp->m_ddev_targp) {
+		xfs_err(mp, "ondisk log corrupt, shutting down fs!");
+		xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_META);
+		return -EFSCORRUPTED;
+	}
+
+	if (!xfs_sb_version_hasrmapbt(&mp->m_sb)) {
+		xfs_warn(mp, "notify_failure() needs rmapbt enabled!");
+		return -EOPNOTSUPP;
+	}
+
+	error = xfs_trans_alloc_empty(mp, &tp);
+	if (error)
+		return error;
+
+	error = xfs_alloc_read_agf(mp, tp, agno, 0, &agf_bp);
+	if (error)
+		goto out_cancel_tp;
+
+	cur = xfs_rmapbt_init_cursor(mp, tp, agf_bp, agf_bp->b_pag);
+
+	/* Construct a range for rmap query */
+	memset(&rmap_low, 0, sizeof(rmap_low));
+	memset(&rmap_high, 0xFF, sizeof(rmap_high));
+	rmap_low.rm_startblock = rmap_high.rm_startblock = agbno;
+	rmap_low.rm_blockcount = rmap_high.rm_blockcount = bcnt;
+
+	error = xfs_rmap_query_range(cur, &rmap_low, &rmap_high,
+				     xfs_corrupt_helper, data);
+
+	xfs_btree_del_cursor(cur, error);
+	xfs_trans_brelse(tp, agf_bp);
+
+out_cancel_tp:
+	xfs_trans_cancel(tp);
+	return error;
+}
+
+static const struct dax_holder_operations xfs_dax_holder_operations = {
+	.notify_failure = xfs_dax_notify_failure,
+};
+
 static const struct super_operations xfs_super_operations = {
 	.alloc_inode		= xfs_fs_alloc_inode,
 	.destroy_inode		= xfs_fs_destroy_inode,
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 359e809516b8..c8a188b76031 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -160,6 +160,9 @@ static inline void fs_put_dax(struct dax_device *dax_dev)
 }
 
 struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev);
+void fs_dax_set_holder(struct dax_device *dax_dev, void *holder,
+		const struct dax_holder_operations *ops);
+void *fs_dax_get_holder(struct dax_device *dax_dev);
 int dax_writeback_mapping_range(struct address_space *mapping,
 		struct dax_device *dax_dev, struct writeback_control *wbc);
 
@@ -191,6 +194,16 @@ static inline struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
 	return NULL;
 }
 
+static inline void fs_dax_set_holder(struct dax_device *dax_dev, void *holder,
+		const struct dax_holder_operations *ops)
+{
+}
+
+static inline void *fs_dax_get_holder(struct dax_device *dax_dev)
+{
+	return NULL;
+}
+
 static inline struct page *dax_layout_busy_page(struct address_space *mapping)
 {
 	return NULL;
-- 
2.32.0