xfs: add media verification ioctl

Source kernel commit: b8accfd65d31f25b9df15ec2419179b6fa0b21d5

Add a new privileged ioctl so that xfs_scrub can ask the kernel to
verify the media of the devices backing an xfs filesystem, and have any
resulting media errors reported to fsnotify and xfs_healer.

To accomplish this, the kernel allocates a folio between the base page
size and 1MB, and issues read IOs to a gradually incrementing range of
one of the storage devices underlying an xfs filesystem.  If any error
occurs, that raw error is reported to the calling process.  If the error
happens to be one of the ones that the kernel considers indicative of
data loss, then it will also be reported to xfs_healthmon and fsnotify.

Driving the verification from the kernel enables xfs (and by extension
xfs_scrub) to have precise control over the size and error handling of
IOs that are issued to the underlying block device, and to emit
notifications about problems to other relevant kernel subsystems
immediately.

Note that the caller is also allowed to reduce the size of the IO and
to ask for a relaxation period after each IO.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

diff --git a/libxfs/xfs_fs.h b/libxfs/xfs_fs.h
index a01303c5de6ce614baa24f04ae181044383019c3..d165de607d179ed18e57cd021336af05c08a9cd5 100644 (file)
--- a/libxfs/xfs_fs.h
+++ b/libxfs/xfs_fs.h
@@ -1160,6 +1160,34 @@ struct xfs_health_file_on_monitored_fs {
        __u32           flags;  /* zero for now */
 };
 
+/* Verify the media of the underlying devices */
+struct xfs_verify_media {
+       __u32   me_dev;         /* I: XFS_DEV_{DATA,LOG,RT} */
+       __u32   me_flags;       /* I: XFS_VERIFY_MEDIA_* */
+
+       /*
+        * IO: inclusive start of disk range to verify, in 512b blocks.
+        * Will be adjusted upwards as media verification succeeds.
+        */
+       __u64   me_start_daddr;
+
+       /*
+        * IO: exclusive end of the disk range to verify, in 512b blocks.
+        * Can be adjusted downwards to match device size.
+        */
+       __u64   me_end_daddr;
+
+       __u32   me_ioerror;     /* O: I/O error (positive) */
+       __u32   me_max_io_size; /* I: maximum IO size in bytes */
+
+       __u32   me_rest_us;     /* I: rest time between IOs, usecs */
+       __u32   me_pad;         /* zero */
+};
+
+#define XFS_VERIFY_MEDIA_REPORT        (1 << 0)        /* report to fsnotify */
+
+#define XFS_VERIFY_MEDIA_FLAGS (XFS_VERIFY_MEDIA_REPORT)
+
 /*
  * ioctl commands that are used by Linux filesystems
  */
@@ -1202,6 +1230,8 @@ struct xfs_health_file_on_monitored_fs {
 #define XFS_IOC_HEALTH_MONITOR _IOW ('X', 68, struct xfs_health_monitor)
 #define XFS_IOC_HEALTH_FD_ON_MONITORED_FS \
                                _IOW ('X', 69, struct xfs_health_file_on_monitored_fs)
+#define XFS_IOC_VERIFY_MEDIA   _IOWR('X', 70, struct xfs_verify_media)
+
 /*
  * ioctl commands that replace IRIX syssgi()'s
  */