[PATCH] btrfs-progs: add cli to forget one or all scanned devices

From: Anand Jain <anand.jain@oracle.com>
To: linux-btrfs@vger.kernel.org
Subject: [PATCH] btrfs-progs: add cli to forget one or all scanned devices
Date: Thu, 26 Jul 2018 19:32:25 +0800	[thread overview]
Message-ID: <20180726113225.1745-3-anand.jain@oracle.com> (raw)
In-Reply-To: <20180726113225.1745-1-anand.jain@oracle.com>

This patch adds cli
  btrfs device forget [dev]
to remove the given device structure in the kernel if the device
is unmounted. If no argument is given it shall remove all stale
(device which are not mounted) from the kernel.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 cmds-device.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 ioctl.h       |  2 ++
 2 files changed, 60 insertions(+)

diff --git a/cmds-device.c b/cmds-device.c
index 86459d1b9564..49cfd4b41adb 100644
--- a/cmds-device.c
+++ b/cmds-device.c
@@ -326,6 +326,63 @@ out:
 	return !!ret;
 }
 
+static const char * const cmd_device_forget_usage[] = {
+	"btrfs device forget [<device>]",
+	"Forget a stale device or all stale devices in btrfs.ko",
+	NULL
+};
+
+static int btrfs_forget_devices(char *path)
+{
+	struct btrfs_ioctl_vol_args args;
+	int ret;
+	int fd;
+
+	fd = open("/dev/btrfs-control", O_RDWR);
+	if (fd < 0)
+		return -errno;
+
+	memset(&args, 0, sizeof(args));
+	if (path)
+		strncpy_null(args.name, path);
+	ret = ioctl(fd, BTRFS_IOC_FORGET_DEV, &args);
+	if (ret)
+		ret = -errno;
+	close(fd);
+	return ret;
+}
+
+static int cmd_device_forget(int argc, char **argv)
+{
+	char *path;
+	int ret = 0;
+
+	if (check_argc_max(argc - optind, 1))
+		usage(cmd_device_forget_usage);
+
+	if (argc == 1) {
+		ret = btrfs_forget_devices(NULL);
+		if (ret)
+			error("Can't forget: %s", strerror(-ret));
+		return ret;
+	}
+
+	path = canonicalize_path(argv[1]);
+	if (!path) {
+		error("Could not canonicalize path '%s': %s",
+					argv[1], strerror(errno));
+		return -ENOENT;
+	}
+
+	ret  = btrfs_forget_devices(path);
+	if (ret)
+		error("Can't forget '%s': %s", path, strerror(-ret));
+
+	free(path);
+
+	return ret;
+}
+
 static const char * const cmd_device_ready_usage[] = {
 	"btrfs device ready <device>",
 	"Check device to see if it has all of its devices in cache for mounting",
@@ -601,6 +658,7 @@ const struct cmd_group device_cmd_group = {
 			CMD_ALIAS },
 		{ "remove", cmd_device_remove, cmd_device_remove_usage, NULL, 0 },
 		{ "scan", cmd_device_scan, cmd_device_scan_usage, NULL, 0 },
+		{ "forget", cmd_device_forget, cmd_device_forget_usage, NULL, 0 },
 		{ "ready", cmd_device_ready, cmd_device_ready_usage, NULL, 0 },
 		{ "stats", cmd_device_stats, cmd_device_stats_usage, NULL, 0 },
 		{ "usage", cmd_device_usage,
diff --git a/ioctl.h b/ioctl.h
index 709e996f401c..e27d80e09392 100644
--- a/ioctl.h
+++ b/ioctl.h
@@ -721,6 +721,8 @@ static inline char *btrfs_err_str(enum btrfs_err_code err_code)
 				   struct btrfs_ioctl_vol_args)
 #define BTRFS_IOC_SCAN_DEV _IOW(BTRFS_IOCTL_MAGIC, 4, \
 				   struct btrfs_ioctl_vol_args)
+#define BTRFS_IOC_FORGET_DEV _IOW(BTRFS_IOCTL_MAGIC, 5, \
+				   struct btrfs_ioctl_vol_args)
 /* trans start and trans end are dangerous, and only for
  * use by applications that know how to avoid the
  * resulting deadlocks
-- 
2.7.0

