[PATCH v7] Add cli and ioctl to forget scanned device(s)

[PATCH v7] Add cli and ioctl to forget scanned device(s)

[Anand Jain]

v7:
 Availalbe for pull from
  btrfs-progs:
   git@github.com:asj/btrfs-progs.git forget
  btrfs.ko:
   git@github.com:asj/btrfs-devel.git misc-next-jul18

 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 v7] 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.

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 d7a54c648c5f..196b0773eedb 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2249,6 +2249,9 @@ 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 51451c0dd8f5..bc1e19663e81 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(path, 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 06d8bb7dd557..82502a7ff6e4 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_fs_info *fs_info,
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 v7] 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

Re: [PATCH v7] Add cli and ioctl to forget scanned device(s)

[Anand Jain]

  Please ignore this. There is a line of code which is un-commit.
  I am sending this series again. Sorry for the noise.

Thanks, Anand



On 07/18/2018 11:07 AM, Anand Jain wrote:
> v7:
>   Availalbe for pull from
>    btrfs-progs:
>     git@github.com:asj/btrfs-progs.git forget
>    btrfs.ko:
>     git@github.com:asj/btrfs-devel.git misc-next-jul18
> 
>   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(+)
>