From: Darrick J. Wong <djwong@xxxxxxxxxx>
Create an ioctl that installs a file descriptor backed by an anon_inode
file that will convey filesystem health events to userspace.
Signed-off-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
---
fs/xfs/Kconfig | 8 +++
fs/xfs/Makefile | 1
fs/xfs/libxfs/xfs_fs.h | 8 +++
fs/xfs/xfs_healthmon.c | 145 ++++++++++++++++++++++++++++++++++++++++++++++++
fs/xfs/xfs_healthmon.h | 16 +++++
fs/xfs/xfs_ioctl.c | 4 +
6 files changed, 182 insertions(+)
create mode 100644 fs/xfs/xfs_healthmon.c
create mode 100644 fs/xfs/xfs_healthmon.h
diff --git a/fs/xfs/Kconfig b/fs/xfs/Kconfig
index 5700bc671a0e92..9d061a8c2786fe 100644
--- a/fs/xfs/Kconfig
+++ b/fs/xfs/Kconfig
@@ -120,6 +120,14 @@ config XFS_RT
If unsure, say N.
+config XFS_HEALTH_MONITOR
+ bool "Report filesystem health events to userspace"
+ depends on XFS_FS
+ select XFS_LIVE_HOOKS
+ default y
+ help
+ Report health events to userspace programs.
+
config XFS_DRAIN_INTENTS
bool
select JUMP_LABEL if HAVE_ARCH_JUMP_LABEL
diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index 4c59d43c77089e..94a9dc7aa7a1d5 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -158,6 +158,7 @@ xfs-$(CONFIG_XFS_DRAIN_INTENTS) += xfs_drain.o
xfs-$(CONFIG_XFS_LIVE_HOOKS) += xfs_hooks.o
xfs-$(CONFIG_XFS_MEMORY_BUFS) += xfs_buf_mem.o
xfs-$(CONFIG_XFS_BTREE_IN_MEM) += libxfs/xfs_btree_mem.o
+xfs-$(CONFIG_XFS_HEALTH_MONITOR) += xfs_healthmon.o
# online scrub/repair
ifeq ($(CONFIG_XFS_ONLINE_SCRUB),y)
diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index f4128dbdf3b9a2..d1a81b02a1a3f3 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -1100,6 +1100,13 @@ struct xfs_map_freesp {
__u64 pad; /* must be zero */
};
+struct xfs_health_monitor {
+ __u64 flags; /* flags */
+ __u8 format; /* output format */
+ __u8 pad1[7]; /* zeroes */
+ __u64 pad2[2]; /* zeroes */
+};
+
/*
* ioctl commands that are used by Linux filesystems
*/
@@ -1141,6 +1148,7 @@ struct xfs_map_freesp {
#define XFS_IOC_RTGROUP_GEOMETRY _IOWR('X', 65, struct xfs_rtgroup_geometry)
#define XFS_IOC_GETFSREFCOUNTS _IOWR('X', 66, struct xfs_getfsrefs_head)
#define XFS_IOC_MAP_FREESP _IOW ('X', 67, struct xfs_map_freesp)
+#define XFS_IOC_HEALTH_MONITOR _IOW ('X', 68, struct xfs_health_monitor)
/*
* ioctl commands that replace IRIX syssgi()'s
diff --git a/fs/xfs/xfs_healthmon.c b/fs/xfs/xfs_healthmon.c
new file mode 100644
index 00000000000000..c5ce5699373c63
--- /dev/null
+++ b/fs/xfs/xfs_healthmon.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2024-2025 Oracle. All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@xxxxxxxxxx>
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_inode.h"
+#include "xfs_trace.h"
+#include "xfs_ag.h"
+#include "xfs_btree.h"
+#include "xfs_da_format.h"
+#include "xfs_da_btree.h"
+#include "xfs_quota_defs.h"
+#include "xfs_rtgroup.h"
+#include "xfs_healthmon.h"
+
+#include <linux/anon_inodes.h>
+#include <linux/eventpoll.h>
+#include <linux/poll.h>
+
+/*
+ * Live Health Monitoring
+ * ======================
+ *
+ * Autonomous self-healing of XFS filesystems requires a means for the kernel
+ * to send filesystem health events to a monitoring daemon in userspace. To
+ * accomplish this, we establish a thread_with_file kthread object to handle
+ * translating internal events about filesystem health into a format that can
+ * be parsed easily by userspace. Then we hook various parts of the filesystem
+ * to supply those internal events to the kthread. Userspace reads events
+ * from the file descriptor returned by the ioctl.
+ *
+ * The healthmon abstraction has a weak reference to the host filesystem mount
+ * so that the queueing and processing of the events do not pin the mount and
+ * cannot slow down the main filesystem. The healthmon object can exist past
+ * the end of the filesystem mount.
+ */
+
+struct xfs_healthmon {
+ struct xfs_mount *mp;
+};
+
+/*
+ * Convey queued event data to userspace. First copy any remaining bytes in
+ * the outbuf, then format the oldest event into the outbuf and copy that too.
+ */
+STATIC ssize_t
+xfs_healthmon_read_iter(
+ struct kiocb *iocb,
+ struct iov_iter *to)
+{
+ return -EIO;
+}
+
+/* Free the health monitoring information. */
+STATIC int
+xfs_healthmon_release(
+ struct inode *inode,
+ struct file *file)
+{
+ struct xfs_healthmon *hm = file->private_data;
+
+ kfree(hm);
+
+ return 0;
+}
+
+/* Validate ioctl parameters. */
+static inline bool
+xfs_healthmon_validate(
+ const struct xfs_health_monitor *hmo)
+{
+ if (hmo->flags)
+ return false;
+ if (hmo->format)
+ return false;
+ if (memchr_inv(&hmo->pad1, 0, sizeof(hmo->pad1)))
+ return false;
+ if (memchr_inv(&hmo->pad2, 0, sizeof(hmo->pad2)))
+ return false;
+ return true;
+}
+
+static const struct file_operations xfs_healthmon_fops = {
+ .owner = THIS_MODULE,
+ .read_iter = xfs_healthmon_read_iter,
+ .release = xfs_healthmon_release,
+};
+
+/*
+ * Create a health monitoring file. Returns an index to the fd table or a
+ * negative errno.
+ */
+long
+xfs_ioc_health_monitor(
+ struct xfs_mount *mp,
+ struct xfs_health_monitor __user *arg)
+{
+ struct xfs_health_monitor hmo;
+ struct xfs_healthmon *hm;
+ char *name;
+ int fd;
+ int ret;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (copy_from_user(&hmo, arg, sizeof(hmo)))
+ return -EFAULT;
+
+ if (!xfs_healthmon_validate(&hmo))
+ return -EINVAL;
+
+ hm = kzalloc(sizeof(*hm), GFP_KERNEL);
+ if (!hm)
+ return -ENOMEM;
+ hm->mp = mp;
+
+ /* Set up VFS file and file descriptor. */
+ name = kasprintf(GFP_KERNEL, "XFS (%s): healthmon", mp->m_super->s_id);
+ if (!name) {
+ ret = -ENOMEM;
+ goto out_hm;
+ }
+
+ fd = anon_inode_getfd(name, &xfs_healthmon_fops, hm,
+ O_CLOEXEC | O_RDONLY);
+ kvfree(name);
+ if (fd < 0) {
+ ret = fd;
+ goto out_hm;
+ }
+
+ return fd;
+
+out_hm:
+ kfree(hm);
+ return ret;
+}
diff --git a/fs/xfs/xfs_healthmon.h b/fs/xfs/xfs_healthmon.h
new file mode 100644
index 00000000000000..07126e39281a0c
--- /dev/null
+++ b/fs/xfs/xfs_healthmon.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) 2024-2025 Oracle. All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@xxxxxxxxxx>
+ */
+#ifndef __XFS_HEALTHMON_H__
+#define __XFS_HEALTHMON_H__
+
+#ifdef CONFIG_XFS_HEALTH_MONITOR
+long xfs_ioc_health_monitor(struct xfs_mount *mp,
+ struct xfs_health_monitor __user *arg);
+#else
+# define xfs_ioc_health_monitor(mp, hmo) (-ENOTTY)
+#endif /* CONFIG_XFS_HEALTH_MONITOR */
+
+#endif /* __XFS_HEALTHMON_H__ */
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 092a3699ff9e75..6c7a30128c7bf6 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -42,6 +42,7 @@
#include "xfs_exchrange.h"
#include "xfs_handle.h"
#include "xfs_rtgroup.h"
+#include "xfs_healthmon.h"
#include <linux/mount.h>
#include <linux/fileattr.h>
@@ -1434,6 +1435,9 @@ xfs_file_ioctl(
case XFS_IOC_MAP_FREESP:
return xfs_ioc_map_freesp(filp, arg);
+ case XFS_IOC_HEALTH_MONITOR:
+ return xfs_ioc_health_monitor(mp, arg);
+
default:
return -ENOTTY;
}
