[PATCH v8] Add cli and ioctl to forget scanned device(s)

[PATCH v8] Add cli and ioctl to forget scanned device(s)

[Anand Jain]

[based on latest misc-next]

v8:
 Change log update in the kernel patch.

v7:
 Use struct btrfs_ioctl_vol_args (instead of struct
  btrfs_ioctl_vol_args_v2) as its inline with other ioctl
  btrfs-control
 The CLI usage remains same. However internally the ioctl flag is not
  required to delete all the unmounted devices. Instead leave
  btrfs_ioctl_vol_args::name NULL.

v6:
 Use the changed fn name btrfs_free_stale_devices().

 Change in title:
 Old v5:
 Cover-letter:
  [PATCH v5] Add cli and ioctl to ignore a scanned device
 Kernel:
  [PATCH v5] btrfs: introduce feature to ignore a btrfs device
 Progs:
  [PATCH v5] btrfs-progs: add 'btrfs device ignore' cli

v5:
  Adds feature to delete all stale devices
  Reuses btrfs_free_stale_devices() fn and so depends on the
    patch-set [1] in the ML.
  Uses struct btrfs_ioctl_vol_args_v2 instead of
    struct btrfs_ioctl_vol_args as arg
  Does the device path matching instead of btrfs_device matching
    (we won't delete the mounted device as btrfs_free_stale_devices()
    checks for it)
v4:
  No change. But as the ML thread may be confusing, so resend.
v3:
  No change. Send to correct ML.
v2:
  Accepts review from Nikolay, details are in the specific patch.
  Patch 1/2 is renamed from
    [PATCH 1/2] btrfs: refactor btrfs_free_stale_device() to get device list delete
  to
    [PATCH 1/2] btrfs: add function to device list delete

Adds cli and ioctl to forget a scanned device or forget all stale
devices in the kernel.

Anand Jain (1):
  btrfs: introduce feature to forget a btrfs device

 fs/btrfs/super.c           | 3 +++
 fs/btrfs/volumes.c         | 9 +++++++++
 fs/btrfs/volumes.h         | 1 +
 include/uapi/linux/btrfs.h | 2 ++
 4 files changed, 15 insertions(+)

Anand Jain (1):
  btrfs-progs: add cli to forget one or all scanned devices

 cmds-device.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 ioctl.h       |  2 ++
 2 files changed, 60 insertions(+)

-- 
2.7.0

[PATCH] btrfs: introduce feature to forget a btrfs device

[Anand Jain]

Support for a new command 'btrfs dev forget [dev]' is proposed here
to undo the effects of 'btrfs dev scan [dev]'. For this purpose
this patch proposes to use ioctl #5 as it was empty.
	IOW(BTRFS_IOCTL_MAGIC, 5, ..)
This patch adds new ioctl BTRFS_IOC_FORGET_DEV which can be sent from
the /dev/btrfs-control to forget one or all devices, (devices which are
not mounted) from the btrfs kernel.

The argument it takes is struct btrfs_ioctl_vol_args, and ::name can be
set to specify the device path. And all unmounted devices can be removed
from the kernel if no device path is provided.

Again, the devices are removed only if the relevant fsid aren't mounted.

This new cli can provide..
 . Release of unwanted btrfs_fs_devices and btrfs_devices memory if the
   device is not going to be mounted.
 . Ability to mount the device in degraded mode when one of the other
   device is corrupted like in split brain raid1.
 . Running test cases which requires btrfs.ko-reload if the rootfs
   is btrfs.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/super.c           | 3 +++
 fs/btrfs/volumes.c         | 9 +++++++++
 fs/btrfs/volumes.h         | 1 +
 include/uapi/linux/btrfs.h | 2 ++
 4 files changed, 15 insertions(+)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 67de3c0fc85b..470a32af474e 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2244,6 +2244,9 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 		ret = PTR_ERR_OR_ZERO(device);
 		mutex_unlock(&uuid_mutex);
 		break;
+	case BTRFS_IOC_FORGET_DEV:
+		ret = btrfs_forget_devices(vol->name);
+		break;
 	case BTRFS_IOC_DEVICES_READY:
 		mutex_lock(&uuid_mutex);
 		device = btrfs_scan_one_device(vol->name, FMODE_READ,
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 8844904f9009..cd54a926141a 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1208,6 +1208,15 @@ static int btrfs_read_disk_super(struct block_device *bdev, u64 bytenr,
 	return 0;
 }
 
+int btrfs_forget_devices(const char *path)
+{
+	mutex_lock(&uuid_mutex);
+	btrfs_free_stale_devices(strlen(path) ? path:NULL, NULL);
+	mutex_unlock(&uuid_mutex);
+
+	return 0;
+}
+
 /*
  * Look for a btrfs signature on a device. This may be called out of the mount path
  * and we are not allowed to call set_blocksize during the scan. The superblock
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 049619176831..1602b5faa7e7 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -405,6 +405,7 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
 		       fmode_t flags, void *holder);
 struct btrfs_device *btrfs_scan_one_device(const char *path,
 					   fmode_t flags, void *holder);
+int btrfs_forget_devices(const char *path);
 int btrfs_close_devices(struct btrfs_fs_devices *fs_devices);
 void btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices, int step);
 void btrfs_assign_next_active_device(struct btrfs_device *device,
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 5ca1d21fc4a7..b1be7f828cb4 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -836,6 +836,8 @@ enum btrfs_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

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

[Anand Jain]

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

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

[Anand Jain]

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>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
---
 cmds-device.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++-----------
 ioctl.h       |  2 ++
 2 files changed, 61 insertions(+), 13 deletions(-)

diff --git a/cmds-device.c b/cmds-device.c
index 2a05f70a76a9..280d6f555377 100644
--- a/cmds-device.c
+++ b/cmds-device.c
@@ -254,10 +254,32 @@ static int cmd_device_delete(int argc, char **argv)
 	return _cmd_device_remove(argc, argv, cmd_device_delete_usage);
 }
 
+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 const char * const cmd_device_scan_usage[] = {
-	"btrfs device scan [(-d|--all-devices)|<device> [<device>...]]",
-	"Scan devices for a btrfs filesystem",
+	"btrfs device scan [(-d|--all-devices)|(-u|--forget)|<device> "\
+							"[<device>...]]",
+	"Scan or forget (deregister) devices for a btrfs filesystem",
 	" -d|--all-devices (deprecated)",
+	" -u|--forget [<device> ..]",
 	NULL
 };
 
@@ -267,37 +289,53 @@ static int cmd_device_scan(int argc, char **argv)
 	int devstart;
 	int all = 0;
 	int ret = 0;
+	int forget = 0;
 
 	optind = 0;
 	while (1) {
 		int c;
 		static const struct option long_options[] = {
 			{ "all-devices", no_argument, NULL, 'd'},
+			{ "forget", no_argument, NULL, 'u'},
 			{ NULL, 0, NULL, 0}
 		};
 
-		c = getopt_long(argc, argv, "d", long_options, NULL);
+		c = getopt_long(argc, argv, "du", long_options, NULL);
 		if (c < 0)
 			break;
 		switch (c) {
 		case 'd':
 			all = 1;
 			break;
+		case 'u':
+			forget = 1;
+			break;
 		default:
 			usage(cmd_device_scan_usage);
 		}
 	}
 	devstart = optind;
 
+	if (all && forget)
+		usage(cmd_device_scan_usage);
+
 	if (all && check_argc_max(argc - optind, 1))
 		usage(cmd_device_scan_usage);
 
 	if (all || argc - optind == 0) {
-		printf("Scanning for Btrfs filesystems\n");
-		ret = btrfs_scan_devices();
-		error_on(ret, "error %d while scanning", ret);
-		ret = btrfs_register_all_devices();
-		error_on(ret, "there are %d errors while registering devices", ret);
+		if (forget) {
+			ret = btrfs_forget_devices(NULL);
+			error_on(ret, "'%s', forget failed",
+				 strerror(-ret));
+		} else {
+			printf("Scanning for Btrfs filesystems\n");
+			ret = btrfs_scan_devices();
+			error_on(ret, "error %d while scanning", ret);
+			ret = btrfs_register_all_devices();
+			error_on(ret,
+				"there are %d errors while registering devices",
+				ret);
+		}
 		goto out;
 	}
 
@@ -315,11 +353,19 @@ static int cmd_device_scan(int argc, char **argv)
 			ret = 1;
 			goto out;
 		}
-		printf("Scanning for Btrfs filesystems in '%s'\n", path);
-		if (btrfs_register_one_device(path) != 0) {
-			ret = 1;
-			free(path);
-			goto out;
+		if (forget) {
+			ret = btrfs_forget_devices(path);
+			if (ret)
+				error("Can't forget '%s': %s",
+							path, strerror(-ret));
+		} else {
+			printf("Scanning for Btrfs filesystems in '%s'\n",
+									path);
+			if (btrfs_register_one_device(path) != 0) {
+				ret = 1;
+				free(path);
+				goto out;
+			}
 		}
 		free(path);
 	}
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
-- 
1.8.3.1

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

[Nikolay Borisov]

On 26.10.18 г. 17:27 ч., Anand Jain wrote:
> 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>

Reviewed-by: Nikolay Borisov <nborisov@suse.com>

> ---
>  cmds-device.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++-----------
>  ioctl.h       |  2 ++
>  2 files changed, 61 insertions(+), 13 deletions(-)
> 
> diff --git a/cmds-device.c b/cmds-device.c
> index 2a05f70a76a9..280d6f555377 100644
> --- a/cmds-device.c
> +++ b/cmds-device.c
> @@ -254,10 +254,32 @@ static int cmd_device_delete(int argc, char **argv)
>  	return _cmd_device_remove(argc, argv, cmd_device_delete_usage);
>  }
>  
> +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 const char * const cmd_device_scan_usage[] = {
> -	"btrfs device scan [(-d|--all-devices)|<device> [<device>...]]",
> -	"Scan devices for a btrfs filesystem",
> +	"btrfs device scan [(-d|--all-devices)|(-u|--forget)|<device> "\
> +							"[<device>...]]",
> +	"Scan or forget (deregister) devices for a btrfs filesystem",
>  	" -d|--all-devices (deprecated)",
> +	" -u|--forget [<device> ..]",
>  	NULL
>  };
>  
> @@ -267,37 +289,53 @@ static int cmd_device_scan(int argc, char **argv)
>  	int devstart;
>  	int all = 0;
>  	int ret = 0;
> +	int forget = 0;
>  
>  	optind = 0;
>  	while (1) {
>  		int c;
>  		static const struct option long_options[] = {
>  			{ "all-devices", no_argument, NULL, 'd'},
> +			{ "forget", no_argument, NULL, 'u'},
>  			{ NULL, 0, NULL, 0}
>  		};
>  
> -		c = getopt_long(argc, argv, "d", long_options, NULL);
> +		c = getopt_long(argc, argv, "du", long_options, NULL);
>  		if (c < 0)
>  			break;
>  		switch (c) {
>  		case 'd':
>  			all = 1;
>  			break;
> +		case 'u':
> +			forget = 1;
> +			break;
>  		default:
>  			usage(cmd_device_scan_usage);
>  		}
>  	}
>  	devstart = optind;
>  
> +	if (all && forget)
> +		usage(cmd_device_scan_usage);
> +
>  	if (all && check_argc_max(argc - optind, 1))
>  		usage(cmd_device_scan_usage);
>  
>  	if (all || argc - optind == 0) {
> -		printf("Scanning for Btrfs filesystems\n");
> -		ret = btrfs_scan_devices();
> -		error_on(ret, "error %d while scanning", ret);
> -		ret = btrfs_register_all_devices();
> -		error_on(ret, "there are %d errors while registering devices", ret);
> +		if (forget) {
> +			ret = btrfs_forget_devices(NULL);
> +			error_on(ret, "'%s', forget failed",
> +				 strerror(-ret));
> +		} else {
> +			printf("Scanning for Btrfs filesystems\n");
> +			ret = btrfs_scan_devices();
> +			error_on(ret, "error %d while scanning", ret);
> +			ret = btrfs_register_all_devices();
> +			error_on(ret,
> +				"there are %d errors while registering devices",
> +				ret);
> +		}
>  		goto out;
>  	}
>  
> @@ -315,11 +353,19 @@ static int cmd_device_scan(int argc, char **argv)
>  			ret = 1;
>  			goto out;
>  		}
> -		printf("Scanning for Btrfs filesystems in '%s'\n", path);
> -		if (btrfs_register_one_device(path) != 0) {
> -			ret = 1;
> -			free(path);
> -			goto out;
> +		if (forget) {
> +			ret = btrfs_forget_devices(path);
> +			if (ret)
> +				error("Can't forget '%s': %s",
> +							path, strerror(-ret));
> +		} else {
> +			printf("Scanning for Btrfs filesystems in '%s'\n",
> +									path);
> +			if (btrfs_register_one_device(path) != 0) {
> +				ret = 1;
> +				free(path);
> +				goto out;
> +			}
>  		}
>  		free(path);
>  	}
> 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
> 

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

[Anand Jain]

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 | 72 ++++++++++++++++++++++++++++++++++++++++++++++++-----------
 ioctl.h       |  2 ++
 2 files changed, 61 insertions(+), 13 deletions(-)

diff --git a/cmds-device.c b/cmds-device.c
index 2a05f70a76a9..280d6f555377 100644
--- a/cmds-device.c
+++ b/cmds-device.c
@@ -254,10 +254,32 @@ static int cmd_device_delete(int argc, char **argv)
 	return _cmd_device_remove(argc, argv, cmd_device_delete_usage);
 }
 
+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 const char * const cmd_device_scan_usage[] = {
-	"btrfs device scan [(-d|--all-devices)|<device> [<device>...]]",
-	"Scan devices for a btrfs filesystem",
+	"btrfs device scan [(-d|--all-devices)|(-u|--forget)|<device> "\
+							"[<device>...]]",
+	"Scan or forget (deregister) devices for a btrfs filesystem",
 	" -d|--all-devices (deprecated)",
+	" -u|--forget [<device> ..]",
 	NULL
 };
 
@@ -267,37 +289,53 @@ static int cmd_device_scan(int argc, char **argv)
 	int devstart;
 	int all = 0;
 	int ret = 0;
+	int forget = 0;
 
 	optind = 0;
 	while (1) {
 		int c;
 		static const struct option long_options[] = {
 			{ "all-devices", no_argument, NULL, 'd'},
+			{ "forget", no_argument, NULL, 'u'},
 			{ NULL, 0, NULL, 0}
 		};
 
-		c = getopt_long(argc, argv, "d", long_options, NULL);
+		c = getopt_long(argc, argv, "du", long_options, NULL);
 		if (c < 0)
 			break;
 		switch (c) {
 		case 'd':
 			all = 1;
 			break;
+		case 'u':
+			forget = 1;
+			break;
 		default:
 			usage(cmd_device_scan_usage);
 		}
 	}
 	devstart = optind;
 
+	if (all && forget)
+		usage(cmd_device_scan_usage);
+
 	if (all && check_argc_max(argc - optind, 1))
 		usage(cmd_device_scan_usage);
 
 	if (all || argc - optind == 0) {
-		printf("Scanning for Btrfs filesystems\n");
-		ret = btrfs_scan_devices();
-		error_on(ret, "error %d while scanning", ret);
-		ret = btrfs_register_all_devices();
-		error_on(ret, "there are %d errors while registering devices", ret);
+		if (forget) {
+			ret = btrfs_forget_devices(NULL);
+			error_on(ret, "'%s', forget failed",
+				 strerror(-ret));
+		} else {
+			printf("Scanning for Btrfs filesystems\n");
+			ret = btrfs_scan_devices();
+			error_on(ret, "error %d while scanning", ret);
+			ret = btrfs_register_all_devices();
+			error_on(ret,
+				"there are %d errors while registering devices",
+				ret);
+		}
 		goto out;
 	}
 
@@ -315,11 +353,19 @@ static int cmd_device_scan(int argc, char **argv)
 			ret = 1;
 			goto out;
 		}
-		printf("Scanning for Btrfs filesystems in '%s'\n", path);
-		if (btrfs_register_one_device(path) != 0) {
-			ret = 1;
-			free(path);
-			goto out;
+		if (forget) {
+			ret = btrfs_forget_devices(path);
+			if (ret)
+				error("Can't forget '%s': %s",
+							path, strerror(-ret));
+		} else {
+			printf("Scanning for Btrfs filesystems in '%s'\n",
+									path);
+			if (btrfs_register_one_device(path) != 0) {
+				ret = 1;
+				free(path);
+				goto out;
+			}
 		}
 		free(path);
 	}
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
-- 
1.8.3.1

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

[Anand Jain]

On 10/26/2018 08:21 PM, Nikolay Borisov wrote:
> 
> 
> On 24.10.2018 07:31, Anand Jain wrote:
>> 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 | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++--------
>>   ioctl.h       |  2 ++
>>   2 files changed, 53 insertions(+), 8 deletions(-)
>>
>> diff --git a/cmds-device.c b/cmds-device.c
>> index 2a05f70a76a9..c2a2b7f304b8 100644
>> --- a/cmds-device.c
>> +++ b/cmds-device.c
>> @@ -254,10 +254,32 @@ static int cmd_device_delete(int argc, char **argv)
>>   	return _cmd_device_remove(argc, argv, cmd_device_delete_usage);
>>   }
>>   
>> +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 const char * const cmd_device_scan_usage[] = {
>> -	"btrfs device scan [(-d|--all-devices)|<device> [<device>...]]",
>> -	"Scan devices for a btrfs filesystem",
>> +	"btrfs device scan [(-d|--all-devices)|(-u|--forget)|<device> "\
>> +							"[<device>...]]",
>> +	"Scan or forget (deregister) devices for a btrfs filesystem",
>>   	" -d|--all-devices (deprecated)",
>> +	" -u|--forget [<device> ..]",
>>   	NULL
>>   };
>>   
>> @@ -267,32 +289,45 @@ static int cmd_device_scan(int argc, char **argv)
>>   	int devstart;
>>   	int all = 0;
>>   	int ret = 0;
>> +	int forget = 0;
>>   
>>   	optind = 0;
>>   	while (1) {
>>   		int c;
>>   		static const struct option long_options[] = {
>>   			{ "all-devices", no_argument, NULL, 'd'},
>> +			{ "forget", no_argument, NULL, 'u'},
>>   			{ NULL, 0, NULL, 0}
>>   		};
>>   
>> -		c = getopt_long(argc, argv, "d", long_options, NULL);
>> +		c = getopt_long(argc, argv, "du", long_options, NULL);
>>   		if (c < 0)
>>   			break;
>>   		switch (c) {
>>   		case 'd':
>>   			all = 1;
>>   			break;
>> +		case 'u':
>> +			forget = 1;
>> +			break;
>>   		default:
>>   			usage(cmd_device_scan_usage);
>>   		}
>>   	}
>>   	devstart = optind;
>>   
>> +	if (all && forget)
>> +		usage(cmd_device_scan_usage);
>> +
>>   	if (all && check_argc_max(argc - optind, 1))
>>   		usage(cmd_device_scan_usage);
>>   
>>   	if (all || argc - optind == 0) {
>> +		if (forget) {
>> +			ret = btrfs_forget_devices(NULL);
>> +			error_on(ret, "error %d while running forget", ret);
>> +			goto out;
>> +		}
> 
> nit: I would prefer to also have an if () {} else {} construct here,
> similar to what you do below.

  Will fix.

  Also, I think I can use sterror() instead of ret, in the error_on().

  Fixed both of these in v11.

Thanks, Anand

>>   		printf("Scanning for Btrfs filesystems\n");
>>   		ret = btrfs_scan_devices();
>>   		error_on(ret, "error %d while scanning", ret);
>> @@ -315,11 +350,19 @@ static int cmd_device_scan(int argc, char **argv)
>>   			ret = 1;
>>   			goto out;
>>   		}
>> -		printf("Scanning for Btrfs filesystems in '%s'\n", path);
>> -		if (btrfs_register_one_device(path) != 0) {
>> -			ret = 1;
>> -			free(path);
>> -			goto out;
>> +		if (forget) {
>> +			ret = btrfs_forget_devices(path);
>> +			if (ret)
>> +				error("Can't forget '%s': %s",
>> +							path, strerror(-ret));
>> +		} else {
>> +			printf("Scanning for Btrfs filesystems in '%s'\n",
>> +									path);
>> +			if (btrfs_register_one_device(path) != 0) {
>> +				ret = 1;
>> +				free(path);
>> +				goto out;
>> +			}
>>   		}
>>   		free(path);
>>   	}
>> 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
>>

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

[Nikolay Borisov]

On 24.10.2018 07:31, Anand Jain wrote:
> 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 | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++--------
>  ioctl.h       |  2 ++
>  2 files changed, 53 insertions(+), 8 deletions(-)
> 
> diff --git a/cmds-device.c b/cmds-device.c
> index 2a05f70a76a9..c2a2b7f304b8 100644
> --- a/cmds-device.c
> +++ b/cmds-device.c
> @@ -254,10 +254,32 @@ static int cmd_device_delete(int argc, char **argv)
>  	return _cmd_device_remove(argc, argv, cmd_device_delete_usage);
>  }
>  
> +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 const char * const cmd_device_scan_usage[] = {
> -	"btrfs device scan [(-d|--all-devices)|<device> [<device>...]]",
> -	"Scan devices for a btrfs filesystem",
> +	"btrfs device scan [(-d|--all-devices)|(-u|--forget)|<device> "\
> +							"[<device>...]]",
> +	"Scan or forget (deregister) devices for a btrfs filesystem",
>  	" -d|--all-devices (deprecated)",
> +	" -u|--forget [<device> ..]",
>  	NULL
>  };
>  
> @@ -267,32 +289,45 @@ static int cmd_device_scan(int argc, char **argv)
>  	int devstart;
>  	int all = 0;
>  	int ret = 0;
> +	int forget = 0;
>  
>  	optind = 0;
>  	while (1) {
>  		int c;
>  		static const struct option long_options[] = {
>  			{ "all-devices", no_argument, NULL, 'd'},
> +			{ "forget", no_argument, NULL, 'u'},
>  			{ NULL, 0, NULL, 0}
>  		};
>  
> -		c = getopt_long(argc, argv, "d", long_options, NULL);
> +		c = getopt_long(argc, argv, "du", long_options, NULL);
>  		if (c < 0)
>  			break;
>  		switch (c) {
>  		case 'd':
>  			all = 1;
>  			break;
> +		case 'u':
> +			forget = 1;
> +			break;
>  		default:
>  			usage(cmd_device_scan_usage);
>  		}
>  	}
>  	devstart = optind;
>  
> +	if (all && forget)
> +		usage(cmd_device_scan_usage);
> +
>  	if (all && check_argc_max(argc - optind, 1))
>  		usage(cmd_device_scan_usage);
>  
>  	if (all || argc - optind == 0) {
> +		if (forget) {
> +			ret = btrfs_forget_devices(NULL);
> +			error_on(ret, "error %d while running forget", ret);
> +			goto out;
> +		}

nit: I would prefer to also have an if () {} else {} construct here,
similar to what you do below.

>  		printf("Scanning for Btrfs filesystems\n");
>  		ret = btrfs_scan_devices();
>  		error_on(ret, "error %d while scanning", ret);
> @@ -315,11 +350,19 @@ static int cmd_device_scan(int argc, char **argv)
>  			ret = 1;
>  			goto out;
>  		}
> -		printf("Scanning for Btrfs filesystems in '%s'\n", path);
> -		if (btrfs_register_one_device(path) != 0) {
> -			ret = 1;
> -			free(path);
> -			goto out;
> +		if (forget) {
> +			ret = btrfs_forget_devices(path);
> +			if (ret)
> +				error("Can't forget '%s': %s",
> +							path, strerror(-ret));
> +		} else {
> +			printf("Scanning for Btrfs filesystems in '%s'\n",
> +									path);
> +			if (btrfs_register_one_device(path) != 0) {
> +				ret = 1;
> +				free(path);
> +				goto out;
> +			}
>  		}
>  		free(path);
>  	}
> 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
> 

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

[Anand Jain]

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 | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++--------
 ioctl.h       |  2 ++
 2 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/cmds-device.c b/cmds-device.c
index 2a05f70a76a9..c2a2b7f304b8 100644
--- a/cmds-device.c
+++ b/cmds-device.c
@@ -254,10 +254,32 @@ static int cmd_device_delete(int argc, char **argv)
 	return _cmd_device_remove(argc, argv, cmd_device_delete_usage);
 }
 
+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 const char * const cmd_device_scan_usage[] = {
-	"btrfs device scan [(-d|--all-devices)|<device> [<device>...]]",
-	"Scan devices for a btrfs filesystem",
+	"btrfs device scan [(-d|--all-devices)|(-u|--forget)|<device> "\
+							"[<device>...]]",
+	"Scan or forget (deregister) devices for a btrfs filesystem",
 	" -d|--all-devices (deprecated)",
+	" -u|--forget [<device> ..]",
 	NULL
 };
 
@@ -267,32 +289,45 @@ static int cmd_device_scan(int argc, char **argv)
 	int devstart;
 	int all = 0;
 	int ret = 0;
+	int forget = 0;
 
 	optind = 0;
 	while (1) {
 		int c;
 		static const struct option long_options[] = {
 			{ "all-devices", no_argument, NULL, 'd'},
+			{ "forget", no_argument, NULL, 'u'},
 			{ NULL, 0, NULL, 0}
 		};
 
-		c = getopt_long(argc, argv, "d", long_options, NULL);
+		c = getopt_long(argc, argv, "du", long_options, NULL);
 		if (c < 0)
 			break;
 		switch (c) {
 		case 'd':
 			all = 1;
 			break;
+		case 'u':
+			forget = 1;
+			break;
 		default:
 			usage(cmd_device_scan_usage);
 		}
 	}
 	devstart = optind;
 
+	if (all && forget)
+		usage(cmd_device_scan_usage);
+
 	if (all && check_argc_max(argc - optind, 1))
 		usage(cmd_device_scan_usage);
 
 	if (all || argc - optind == 0) {
+		if (forget) {
+			ret = btrfs_forget_devices(NULL);
+			error_on(ret, "error %d while running forget", ret);
+			goto out;
+		}
 		printf("Scanning for Btrfs filesystems\n");
 		ret = btrfs_scan_devices();
 		error_on(ret, "error %d while scanning", ret);
@@ -315,11 +350,19 @@ static int cmd_device_scan(int argc, char **argv)
 			ret = 1;
 			goto out;
 		}
-		printf("Scanning for Btrfs filesystems in '%s'\n", path);
-		if (btrfs_register_one_device(path) != 0) {
-			ret = 1;
-			free(path);
-			goto out;
+		if (forget) {
+			ret = btrfs_forget_devices(path);
+			if (ret)
+				error("Can't forget '%s': %s",
+							path, strerror(-ret));
+		} else {
+			printf("Scanning for Btrfs filesystems in '%s'\n",
+									path);
+			if (btrfs_register_one_device(path) != 0) {
+				ret = 1;
+				free(path);
+				goto out;
+			}
 		}
 		free(path);
 	}
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
-- 
1.8.3.1

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

[Anand Jain]

On 10/12/2018 05:03 PM, Nikolay Borisov wrote:
> 
> 
> On 12.10.2018 07:06, Anand Jain wrote:
>> 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 | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++---------
>>   ioctl.h       |  2 ++
>>   2 files changed, 56 insertions(+), 9 deletions(-)
>>
>> diff --git a/cmds-device.c b/cmds-device.c
>> index 2a05f70a76a9..ecc391ea01d8 100644
>> --- a/cmds-device.c
>> +++ b/cmds-device.c
>> @@ -254,10 +254,32 @@ static int cmd_device_delete(int argc, char **argv)
>>   	return _cmd_device_remove(argc, argv, cmd_device_delete_usage);
>>   }
>>   
>> +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 const char * const cmd_device_scan_usage[] = {
>> -	"btrfs device scan [(-d|--all-devices)|<device> [<device>...]]",
>> -	"Scan devices for a btrfs filesystem",
>> +	"btrfs device scan [(-d|--all-devices)|-u|--forget|<device> "\
>> +							"[<device>...]]",
>> +	"Scan or forget (deregister) devices for a btrfs filesystem",
>>   	" -d|--all-devices (deprecated)",
>> +	" -u|--forget [<device> ..]",
>>   	NULL
>>   };
>>   
>> @@ -267,32 +289,40 @@ static int cmd_device_scan(int argc, char **argv)
>>   	int devstart;
>>   	int all = 0;
>>   	int ret = 0;
>> +	int forget = 0;
>>   
>>   	optind = 0;
>>   	while (1) {
>>   		int c;
>>   		static const struct option long_options[] = {
>>   			{ "all-devices", no_argument, NULL, 'd'},
>> +			{ "forget", no_argument, NULL, 'u'},
>>   			{ NULL, 0, NULL, 0}
>>   		};
>>   
>> -		c = getopt_long(argc, argv, "d", long_options, NULL);
>> +		c = getopt_long(argc, argv, "du", long_options, NULL);
>>   		if (c < 0)
>>   			break;
>>   		switch (c) {
>>   		case 'd':
>>   			all = 1;
>>   			break;
>> +		case 'u':
>> +			forget = 1;
>> +			break;
>>   		default:
>>   			usage(cmd_device_scan_usage);
>>   		}
>>   	}
>>   	devstart = optind;
>>   
>> +	if (all && forget)
>> +		usage(cmd_device_scan_usage);
>> +
>>   	if (all && check_argc_max(argc - optind, 1))
>>   		usage(cmd_device_scan_usage);
>>   
>> -	if (all || argc - optind == 0) {
>> +	if (!forget && (all || argc - optind == 0)) {
>>   		printf("Scanning for Btrfs filesystems\n");
>>   		ret = btrfs_scan_devices();
>>   		error_on(ret, "error %d while scanning", ret);
>> @@ -301,6 +331,13 @@ static int cmd_device_scan(int argc, char **argv)
>>   		goto out;
>>   	}
>>   
>> +	if (forget && (all || argc - optind == 0)) {
> 
> You cannot ever have (forget && all) since you specifically call usage()
> above, just remove the 'all'. Furthermore, I think the code will be more
> legible if it's part of an else if rather than a plain if construct. > In fact the whole function will be more readable. I.e you will have the
> error conditions at the to, followed by "all device scan" case, followed
> by "all device forget" and in the final else branch you will have the
> specific device handling. 

  Originally the -d | --all option is bit broken.
  The -d | --all expects either no arguments OR only one device as an 
argument.

         if (all && check_argc_max(argc - optind, 1))
                 usage(cmd_device_scan_usage);

  Now because of

     if (all || argc - optind == 0) {

    The cli 'btrfs device scan --all /dev/sdb' which should have scanned
     only one device, ends up scanning all the devices and I am not
     trying to fix this bug in this patch because..
   . -d|--all is marked as deprecated, I hope -d option would go away
   . For now some script might be using this bug as a feature, and fixing
     this bug might lead to mount failure.

  However still there is some opportunity to make the my patch more 
readable, thanks for the comments pls see v10 if it is much better?

> The increased indentation level won't be a
> problem since the longest lines are string prints and we are not
> wrapping those.
> 
> 
>> +		ret = btrfs_forget_devices(NULL);
>> +		if (ret)
>> +			error("Can't forget: %s", strerror(-ret));
>> +		goto out;
>> +	}
>> +
>>   	for( i = devstart ; i < argc ; i++ ){
>>   		char *path;
>>   
>> @@ -315,11 +352,19 @@ static int cmd_device_scan(int argc, char **argv)
>>   			ret = 1;
>>   			goto out;
>>   		}
>> -		printf("Scanning for Btrfs filesystems in '%s'\n", path);
>> -		if (btrfs_register_one_device(path) != 0) {
>> -			ret = 1;
>> -			free(path);
>> -			goto out;
>> +		if (forget) {
>> +			ret = btrfs_forget_devices(path);
>> +			if (ret)
>> +				error("Can't forget '%s': %s",
>> +							path, strerror(-ret));
> 
> For consistency sake I think this error printout should be moved inside
> btrfs_forget_devices() similarly to what btrfs_register_one_device does
> on error.

  Where possible we are trying to move the printing to the parent
  functions, so that these helper functions can be used as a/part
  of the library function. As here we can successfully return the unique
  errno for the two possible errors, I would like to keep it as
  it is as of now.

Thanks, Anand

>> +		} else {
>> +			printf("Scanning for Btrfs filesystems in '%s'\n",
>> +									path);
>> +			if (btrfs_register_one_device(path) != 0) {
>> +				ret = 1;
>> +				free(path);
>> +				goto out;
>> +			}
>>   		}
>>   		free(path);
>>   	}
>> 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
>>

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

[Nikolay Borisov]

On 12.10.2018 07:06, Anand Jain wrote:
> 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 | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++---------
>  ioctl.h       |  2 ++
>  2 files changed, 56 insertions(+), 9 deletions(-)
> 
> diff --git a/cmds-device.c b/cmds-device.c
> index 2a05f70a76a9..ecc391ea01d8 100644
> --- a/cmds-device.c
> +++ b/cmds-device.c
> @@ -254,10 +254,32 @@ static int cmd_device_delete(int argc, char **argv)
>  	return _cmd_device_remove(argc, argv, cmd_device_delete_usage);
>  }
>  
> +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 const char * const cmd_device_scan_usage[] = {
> -	"btrfs device scan [(-d|--all-devices)|<device> [<device>...]]",
> -	"Scan devices for a btrfs filesystem",
> +	"btrfs device scan [(-d|--all-devices)|-u|--forget|<device> "\
> +							"[<device>...]]",
> +	"Scan or forget (deregister) devices for a btrfs filesystem",
>  	" -d|--all-devices (deprecated)",
> +	" -u|--forget [<device> ..]",
>  	NULL
>  };
>  
> @@ -267,32 +289,40 @@ static int cmd_device_scan(int argc, char **argv)
>  	int devstart;
>  	int all = 0;
>  	int ret = 0;
> +	int forget = 0;
>  
>  	optind = 0;
>  	while (1) {
>  		int c;
>  		static const struct option long_options[] = {
>  			{ "all-devices", no_argument, NULL, 'd'},
> +			{ "forget", no_argument, NULL, 'u'},
>  			{ NULL, 0, NULL, 0}
>  		};
>  
> -		c = getopt_long(argc, argv, "d", long_options, NULL);
> +		c = getopt_long(argc, argv, "du", long_options, NULL);
>  		if (c < 0)
>  			break;
>  		switch (c) {
>  		case 'd':
>  			all = 1;
>  			break;
> +		case 'u':
> +			forget = 1;
> +			break;
>  		default:
>  			usage(cmd_device_scan_usage);
>  		}
>  	}
>  	devstart = optind;
>  
> +	if (all && forget)
> +		usage(cmd_device_scan_usage);
> +
>  	if (all && check_argc_max(argc - optind, 1))
>  		usage(cmd_device_scan_usage);
>  
> -	if (all || argc - optind == 0) {
> +	if (!forget && (all || argc - optind == 0)) {
>  		printf("Scanning for Btrfs filesystems\n");
>  		ret = btrfs_scan_devices();
>  		error_on(ret, "error %d while scanning", ret);
> @@ -301,6 +331,13 @@ static int cmd_device_scan(int argc, char **argv)
>  		goto out;
>  	}
>  
> +	if (forget && (all || argc - optind == 0)) {

You cannot ever have (forget && all) since you specifically call usage()
above, just remove the 'all'. Furthermore, I think the code will be more
legible if it's part of an else if rather than a plain if construct. In
fact the whole function will be more readable. I.e you will have the
error conditions at the to, followed by "all device scan" case, followed
by "all device forget" and in the final else branch you will have the
specific device handling. The increased indentation level won't be a
problem since the longest lines are string prints and we are not
wrapping those.


> +		ret = btrfs_forget_devices(NULL);
> +		if (ret)
> +			error("Can't forget: %s", strerror(-ret));
> +		goto out;
> +	}
> +
>  	for( i = devstart ; i < argc ; i++ ){
>  		char *path;
>  
> @@ -315,11 +352,19 @@ static int cmd_device_scan(int argc, char **argv)
>  			ret = 1;
>  			goto out;
>  		}
> -		printf("Scanning for Btrfs filesystems in '%s'\n", path);
> -		if (btrfs_register_one_device(path) != 0) {
> -			ret = 1;
> -			free(path);
> -			goto out;
> +		if (forget) {
> +			ret = btrfs_forget_devices(path);
> +			if (ret)
> +				error("Can't forget '%s': %s",
> +							path, strerror(-ret));

For consistency sake I think this error printout should be moved inside
btrfs_forget_devices() similarly to what btrfs_register_one_device does
on error.

> +		} else {
> +			printf("Scanning for Btrfs filesystems in '%s'\n",
> +									path);
> +			if (btrfs_register_one_device(path) != 0) {
> +				ret = 1;
> +				free(path);
> +				goto out;
> +			}
>  		}
>  		free(path);
>  	}
> 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
> 

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

[Anand Jain]

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 | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++---------
 ioctl.h       |  2 ++
 2 files changed, 56 insertions(+), 9 deletions(-)

diff --git a/cmds-device.c b/cmds-device.c
index 2a05f70a76a9..ecc391ea01d8 100644
--- a/cmds-device.c
+++ b/cmds-device.c
@@ -254,10 +254,32 @@ static int cmd_device_delete(int argc, char **argv)
 	return _cmd_device_remove(argc, argv, cmd_device_delete_usage);
 }
 
+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 const char * const cmd_device_scan_usage[] = {
-	"btrfs device scan [(-d|--all-devices)|<device> [<device>...]]",
-	"Scan devices for a btrfs filesystem",
+	"btrfs device scan [(-d|--all-devices)|-u|--forget|<device> "\
+							"[<device>...]]",
+	"Scan or forget (deregister) devices for a btrfs filesystem",
 	" -d|--all-devices (deprecated)",
+	" -u|--forget [<device> ..]",
 	NULL
 };
 
@@ -267,32 +289,40 @@ static int cmd_device_scan(int argc, char **argv)
 	int devstart;
 	int all = 0;
 	int ret = 0;
+	int forget = 0;
 
 	optind = 0;
 	while (1) {
 		int c;
 		static const struct option long_options[] = {
 			{ "all-devices", no_argument, NULL, 'd'},
+			{ "forget", no_argument, NULL, 'u'},
 			{ NULL, 0, NULL, 0}
 		};
 
-		c = getopt_long(argc, argv, "d", long_options, NULL);
+		c = getopt_long(argc, argv, "du", long_options, NULL);
 		if (c < 0)
 			break;
 		switch (c) {
 		case 'd':
 			all = 1;
 			break;
+		case 'u':
+			forget = 1;
+			break;
 		default:
 			usage(cmd_device_scan_usage);
 		}
 	}
 	devstart = optind;
 
+	if (all && forget)
+		usage(cmd_device_scan_usage);
+
 	if (all && check_argc_max(argc - optind, 1))
 		usage(cmd_device_scan_usage);
 
-	if (all || argc - optind == 0) {
+	if (!forget && (all || argc - optind == 0)) {
 		printf("Scanning for Btrfs filesystems\n");
 		ret = btrfs_scan_devices();
 		error_on(ret, "error %d while scanning", ret);
@@ -301,6 +331,13 @@ static int cmd_device_scan(int argc, char **argv)
 		goto out;
 	}
 
+	if (forget && (all || argc - optind == 0)) {
+		ret = btrfs_forget_devices(NULL);
+		if (ret)
+			error("Can't forget: %s", strerror(-ret));
+		goto out;
+	}
+
 	for( i = devstart ; i < argc ; i++ ){
 		char *path;
 
@@ -315,11 +352,19 @@ static int cmd_device_scan(int argc, char **argv)
 			ret = 1;
 			goto out;
 		}
-		printf("Scanning for Btrfs filesystems in '%s'\n", path);
-		if (btrfs_register_one_device(path) != 0) {
-			ret = 1;
-			free(path);
-			goto out;
+		if (forget) {
+			ret = btrfs_forget_devices(path);
+			if (ret)
+				error("Can't forget '%s': %s",
+							path, strerror(-ret));
+		} else {
+			printf("Scanning for Btrfs filesystems in '%s'\n",
+									path);
+			if (btrfs_register_one_device(path) != 0) {
+				ret = 1;
+				free(path);
+				goto out;
+			}
 		}
 		free(path);
 	}
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
-- 
1.8.3.1

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

[Anand Jain]

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

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

[Anand Jain]

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