[PATCH 1/4] btrfs: add ioctl BTRFS_IOC_DEV_PROPERTIES.

[PATCH 1/4] btrfs: add ioctl BTRFS_IOC_DEV_PROPERTIES.

[Goffredo Baroncelli]

From: Goffredo Baroncelli <kreijack@inwind.it>

This ioctl is a base for returning / setting information from / to  the
fields of the btrfs_dev_item object.

For now only the "type" field is returned / set.

Signed-off-by: Goffredo Baroncelli <kreijack@inwind.it>
---
 fs/btrfs/ioctl.c           | 68 ++++++++++++++++++++++++++++++++++++++
 fs/btrfs/volumes.c         |  2 +-
 fs/btrfs/volumes.h         |  2 ++
 include/uapi/linux/btrfs.h | 39 ++++++++++++++++++++++
 4 files changed, 110 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a8c60d46d19c..07898ee3a08d 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4851,6 +4851,72 @@ static int btrfs_ioctl_set_features(struct file *file, void __user *arg)
 	return ret;
 }
 
+static long btrfs_ioctl_dev_properties(struct file *file,
+						void __user *argp)
+{
+	struct inode *inode = file_inode(file);
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_ioctl_dev_properties dev_props;
+	struct btrfs_device	*device;
+	struct btrfs_root *root = fs_info->chunk_root;
+	struct btrfs_trans_handle *trans;
+	int ret;
+	u64 prev_type;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (copy_from_user(&dev_props, argp, sizeof(dev_props)))
+		return -EFAULT;
+
+	device = btrfs_find_device(fs_info->fs_devices, dev_props.devid,
+				NULL, NULL);
+	if (!device) {
+		btrfs_info(fs_info, "change_dev_properties: unable to find device %llu",
+			   dev_props.devid);
+		return -ENODEV;
+	}
+
+	if (dev_props.properties & BTRFS_DEV_PROPERTY_READ) {
+		u64 props = dev_props.properties;
+
+		memset(&dev_props, 0, sizeof(dev_props));
+		if (props & BTRFS_DEV_PROPERTY_TYPE) {
+			dev_props.properties = BTRFS_DEV_PROPERTY_TYPE;
+			dev_props.type = device->type;
+		}
+		if (copy_to_user(argp, &dev_props, sizeof(dev_props)))
+			return -EFAULT;
+		return 0;
+	}
+
+	/* it is possible to set only BTRFS_DEV_PROPERTY_TYPE for now */
+	if (dev_props.properties & ~(BTRFS_DEV_PROPERTY_TYPE))
+		return -EPERM;
+
+	trans = btrfs_start_transaction(root, 1);
+	if (IS_ERR(trans))
+		return PTR_ERR(trans);
+
+	prev_type = device->type;
+	device->type = dev_props.type;
+	ret = btrfs_update_device(trans, device);
+
+	if (ret < 0) {
+		btrfs_abort_transaction(trans, ret);
+		btrfs_end_transaction(trans);
+		device->type = prev_type;
+		return  ret;
+	}
+
+	ret = btrfs_commit_transaction(trans);
+	if (ret < 0)
+		device->type = prev_type;
+
+	return ret;
+
+}
+
 static int _btrfs_ioctl_send(struct file *file, void __user *argp, bool compat)
 {
 	struct btrfs_ioctl_send_args *arg;
@@ -5034,6 +5100,8 @@ long btrfs_ioctl(struct file *file, unsigned int
 		return btrfs_ioctl_get_subvol_rootref(file, argp);
 	case BTRFS_IOC_INO_LOOKUP_USER:
 		return btrfs_ioctl_ino_lookup_user(file, argp);
+	case BTRFS_IOC_DEV_PROPERTIES:
+		return btrfs_ioctl_dev_properties(file, argp);
 	}
 
 	return -ENOTTY;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b8fab44394f5..0c649b444dcd 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2809,7 +2809,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
 	return ret;
 }
 
-static noinline int btrfs_update_device(struct btrfs_trans_handle *trans,
+int btrfs_update_device(struct btrfs_trans_handle *trans,
 					struct btrfs_device *device)
 {
 	int ret;
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index d4c3e0dd32b8..0c07b8deecab 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -600,5 +600,7 @@ int btrfs_bg_type_to_factor(u64 flags);
 const char *btrfs_bg_type_to_raid_name(u64 flags);
 int btrfs_verify_dev_extents(struct btrfs_fs_info *fs_info);
 int btrfs_repair_one_zone(struct btrfs_fs_info *fs_info, u64 logical);
+int btrfs_update_device(struct btrfs_trans_handle *trans,
+					struct btrfs_device *device);
 
 #endif
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 5df73001aad4..bab35d3f819c 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -860,6 +860,43 @@ struct btrfs_ioctl_get_subvol_rootref_args {
 		__u8 align[7];
 };
 
+#define BTRFS_DEV_PROPERTY_TYPE		(1ULL << 0)
+#define BTRFS_DEV_PROPERTY_DEV_GROUP	(1ULL << 1)
+#define BTRFS_DEV_PROPERTY_SEEK_SPEED	(1ULL << 2)
+#define BTRFS_DEV_PROPERTY_BANDWIDTH	(1ULL << 3)
+#define BTRFS_DEV_PROPERTY_READ		(1ULL << 60)
+
+/*
+ * The ioctl BTRFS_IOC_DEV_PROPERTIES can read and write the device properties.
+ *
+ * The properties that the user want to write have to be set
+ * in the 'properties' field using the BTRFS_DEV_PROPERTY_xxxx constants.
+ *
+ * If the ioctl is used to read the device properties, the bit
+ * BTRFS_DEV_PROPERTY_READ has to be set in the 'properties' field.
+ * In this case the properties that the user want have to be set in the
+ * 'properties' field. The kernel doesn't return a property that was not
+ * required, however it may return a subset of the requested properties.
+ * The returned properties have the corrispondent BTRFS_DEV_PROPERTY_xxxx
+ * flag set in the 'properties' field.
+ *
+ * Up to 2020/05/11 the only properties that can be read/write is the 'type'
+ * one.
+ */
+struct btrfs_ioctl_dev_properties {
+	__u64	devid;
+	__u64	properties;
+	__u64	type;
+	__u32	dev_group;
+	__u8	seek_speed;
+	__u8	bandwidth;
+
+	/*
+	 * for future expansion, pad up to 1k
+	 */
+	__u8	reserved[1024-30];
+};
+
 /* Error codes as returned by the kernel */
 enum btrfs_err_code {
 	BTRFS_ERROR_DEV_RAID1_MIN_NOT_MET = 1,
@@ -988,5 +1025,7 @@ enum btrfs_err_code {
 				struct btrfs_ioctl_ino_lookup_user_args)
 #define BTRFS_IOC_SNAP_DESTROY_V2 _IOW(BTRFS_IOCTL_MAGIC, 63, \
 				struct btrfs_ioctl_vol_args_v2)
+#define BTRFS_IOC_DEV_PROPERTIES _IOW(BTRFS_IOCTL_MAGIC, 64, \
+				struct btrfs_ioctl_dev_properties)
 
 #endif /* _UAPI_LINUX_BTRFS_H */
-- 
2.30.0

[PATCH 2/4] btrfs: add flags to give an hint to the chunk allocator

[Goffredo Baroncelli]

From: Goffredo Baroncelli <kreijack@inwind.it>

Add the following flags to give an hint about which chunk should be
allocated in which a disk.
The following flags are created:

- BTRFS_DEV_ALLOCATION_PREFERRED_DATA
  preferred data chunk, but metadata chunk allowed
- BTRFS_DEV_ALLOCATION_PREFERRED_METADATA
  preferred metadata chunk, but data chunk allowed
- BTRFS_DEV_ALLOCATION_METADATA_ONLY
  only metadata chunk allowed
- BTRFS_DEV_ALLOCATION_DATA_ONLY
  only data chunk allowed

Signed-off-by: Goffredo Baroncelli <kreijack@inwid.it>
---
 include/uapi/linux/btrfs_tree.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index 58d7cff9afb1..25f522bcdadc 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -361,6 +361,20 @@ struct btrfs_key {
 	__u64 offset;
 } __attribute__ ((__packed__));
 
+/* dev_item.type */
+
+/* btrfs chunk allocation hints */
+#define BTRFS_DEV_ALLOCATION_MASK_BIT_COUNT	3
+/* preferred data chunk, but metadata chunk allowed */
+#define BTRFS_DEV_ALLOCATION_PREFERRED_DATA	(0ULL)
+/* preferred metadata chunk, but data chunk allowed */
+#define BTRFS_DEV_ALLOCATION_PREFERRED_METADATA	(1ULL)
+/* only metadata chunk are allowed */
+#define BTRFS_DEV_ALLOCATION_METADATA_ONLY	(2ULL)
+/* only data chunk allowed */
+#define BTRFS_DEV_ALLOCATION_DATA_ONLY		(3ULL)
+/* 5..7 are unused values */
+
 struct btrfs_dev_item {
 	/* the internal btrfs device id */
 	__le64 devid;
-- 
2.30.0

[PATCH 3/4] btrfs: export dev_item.type in /sys/fs/btrfs/<uuid>/devinfo/<devid>/type

[Goffredo Baroncelli]

From: Goffredo Baroncelli <kreijack@inwind.it>

Signed-off-by: Goffredo Baroncelli <kreijack@inwind.it>
---
 fs/btrfs/sysfs.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 6eb1c50fa98c..9b2a18911de6 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -1418,11 +1418,22 @@ static ssize_t btrfs_devinfo_writeable_show(struct kobject *kobj,
 }
 BTRFS_ATTR(devid, writeable, btrfs_devinfo_writeable_show);
 
+static ssize_t btrfs_devinfo_type_show(struct kobject *kobj,
+					    struct kobj_attribute *a, char *buf)
+{
+	struct btrfs_device *device = container_of(kobj, struct btrfs_device,
+						   devid_kobj);
+
+	return scnprintf(buf, PAGE_SIZE, "0x%08llx\n", device->type);
+}
+BTRFS_ATTR(devid, type, btrfs_devinfo_type_show);
+
 static struct attribute *devid_attrs[] = {
 	BTRFS_ATTR_PTR(devid, in_fs_metadata),
 	BTRFS_ATTR_PTR(devid, missing),
 	BTRFS_ATTR_PTR(devid, replace_target),
 	BTRFS_ATTR_PTR(devid, writeable),
+	BTRFS_ATTR_PTR(devid, type),
 	NULL
 };
 ATTRIBUTE_GROUPS(devid);
-- 
2.30.0

[PATCH 4/4] btrfs: add allocator_hint mode

[Goffredo Baroncelli]

From: Goffredo Baroncelli <kreijack@inwind.it>

When this mode is enabled, the chunk allocation policy is modified as
follow.

Each disk may have a different tag:
- BTRFS_DEV_ALLOCATION_PREFERRED_METADATA
- BTRFS_DEV_ALLOCATION_METADATA_ONLY
- BTRFS_DEV_ALLOCATION_DATA_ONLY
- BTRFS_DEV_ALLOCATION_PREFERRED_DATA (default)

Where:
- ALLOCATION_PREFERRED_X means that it is preferred to use this disk for
the X chunk type (the other type may be allowed when the space is low)
- ALLOCATION_X_ONLY means that it is used *only* for the X chunk type.
This means also that it is a preferred choice.

Each time the allocator allocates a chunk of type X , first it takes the
disks tagged as ALLOCATION_X_ONLY or ALLOCATION_PREFERRED_X; if the space
is not enough, it uses also the disks tagged as ALLOCATION_METADATA_ONLY;
if the space is not enough, it uses also the other disks, with the
exception of the one marked as ALLOCATION_PREFERRED_Y, where Y the other
type of chunk (i.e. not X).

Signed-off-by: Goffredo Baroncelli <kreijack@inwind.it>
---
 fs/btrfs/volumes.c | 98 +++++++++++++++++++++++++++++++++++++++++++++-
 fs/btrfs/volumes.h |  1 +
 2 files changed, 98 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 0c649b444dcd..7ab10640758c 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -153,6 +153,20 @@ const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = {
 	},
 };
 
+#define BTRFS_DEV_ALLOCATION_MASK ((1ULL << \
+		BTRFS_DEV_ALLOCATION_MASK_BIT_COUNT) - 1)
+#define BTRFS_DEV_ALLOCATION_MASK_COUNT (1ULL << \
+		BTRFS_DEV_ALLOCATION_MASK_BIT_COUNT)
+
+static const char alloc_hint_map[BTRFS_DEV_ALLOCATION_MASK_COUNT] = {
+	[BTRFS_DEV_ALLOCATION_DATA_ONLY] = -1,
+	[BTRFS_DEV_ALLOCATION_PREFERRED_DATA] = 0,
+	[BTRFS_DEV_ALLOCATION_PREFERRED_METADATA] = 1,
+	[BTRFS_DEV_ALLOCATION_METADATA_ONLY] = 2,
+	/* the other values are set to 0 */
+};
+
+
 const char *btrfs_bg_type_to_raid_name(u64 flags)
 {
 	const int index = btrfs_bg_flags_to_raid_index(flags);
@@ -4872,13 +4886,18 @@ static int btrfs_add_system_chunk(struct btrfs_fs_info *fs_info,
 }
 
 /*
- * sort the devices in descending order by max_avail, total_avail
+ * sort the devices in descending order by alloc_hint,
+ * max_avail, total_avail
  */
 static int btrfs_cmp_device_info(const void *a, const void *b)
 {
 	const struct btrfs_device_info *di_a = a;
 	const struct btrfs_device_info *di_b = b;
 
+	if (di_a->alloc_hint > di_b->alloc_hint)
+		return -1;
+	if (di_a->alloc_hint < di_b->alloc_hint)
+		return 1;
 	if (di_a->max_avail > di_b->max_avail)
 		return -1;
 	if (di_a->max_avail < di_b->max_avail)
@@ -5039,6 +5058,8 @@ static int gather_device_info(struct btrfs_fs_devices *fs_devices,
 	int ndevs = 0;
 	u64 max_avail;
 	u64 dev_offset;
+	int hint;
+	int i;
 
 	/*
 	 * in the first pass through the devices list, we gather information
@@ -5091,16 +5112,91 @@ static int gather_device_info(struct btrfs_fs_devices *fs_devices,
 		devices_info[ndevs].max_avail = max_avail;
 		devices_info[ndevs].total_avail = total_avail;
 		devices_info[ndevs].dev = device;
+
+		if ((ctl->type & BTRFS_BLOCK_GROUP_DATA) &&
+		     (ctl->type & BTRFS_BLOCK_GROUP_METADATA)) {
+			/*
+			 * if mixed bg set all the alloc_hint
+			 * fields to the same value, so the sorting
+			 * is not affected
+			 */
+			devices_info[ndevs].alloc_hint = 0;
+		} else if (ctl->type & BTRFS_BLOCK_GROUP_DATA) {
+			hint = device->type & BTRFS_DEV_ALLOCATION_MASK;
+
+			/*
+			 * skip BTRFS_DEV_METADATA_ONLY disks
+			 */
+			if (hint == BTRFS_DEV_ALLOCATION_METADATA_ONLY)
+				continue;
+			/*
+			 * if a data chunk must be allocated,
+			 * sort also by hint (data disk
+			 * higher priority)
+			 */
+			devices_info[ndevs].alloc_hint = -alloc_hint_map[hint];
+		} else { /* BTRFS_BLOCK_GROUP_METADATA */
+			hint = device->type & BTRFS_DEV_ALLOCATION_MASK;
+
+			/*
+			 * skip BTRFS_DEV_DATA_ONLY disks
+			 */
+			if (hint == BTRFS_DEV_ALLOCATION_DATA_ONLY)
+				continue;
+			/*
+			 * if a data chunk must be allocated,
+			 * sort also by hint (metadata hint
+			 * higher priority)
+			 */
+			devices_info[ndevs].alloc_hint = alloc_hint_map[hint];
+		}
+
 		++ndevs;
 	}
 	ctl->ndevs = ndevs;
 
+	/*
+	 * no devices available
+	 */
+	if (!ndevs)
+		return 0;
+
 	/*
 	 * now sort the devices by hole size / available space
 	 */
 	sort(devices_info, ndevs, sizeof(struct btrfs_device_info),
 	     btrfs_cmp_device_info, NULL);
 
+	/*
+	 * select the minimum set of disks grouped by hint that
+	 * can host the chunk
+	 */
+	ndevs = 0;
+	while (ndevs < ctl->ndevs) {
+		hint = devices_info[ndevs++].alloc_hint;
+		while (ndevs < ctl->ndevs &&
+		       devices_info[ndevs].alloc_hint == hint)
+				ndevs++;
+		if (ndevs >= ctl->devs_min)
+			break;
+	}
+
+	BUG_ON(ndevs > ctl->ndevs);
+	ctl->ndevs = ndevs;
+
+	/*
+	 * the next layers require the devices_info ordered by
+	 * max_avail. If we are returing two (or more) different
+	 * group of alloc_hint, this is not always true. So sort
+	 * these gain.
+	 */
+
+	for (i = 0 ; i < ndevs ; i++)
+		devices_info[i].alloc_hint = 0;
+
+	sort(devices_info, ndevs, sizeof(struct btrfs_device_info),
+	     btrfs_cmp_device_info, NULL);
+
 	return 0;
 }
 
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 0c07b8deecab..d192aa78f03f 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -366,6 +366,7 @@ struct btrfs_device_info {
 	u64 dev_offset;
 	u64 max_avail;
 	u64 total_avail;
+	int alloc_hint;
 };
 
 struct btrfs_raid_attr {
-- 
2.30.0

Re: [PATCH 1/4] btrfs: add ioctl BTRFS_IOC_DEV_PROPERTIES.

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 3739 bytes --]

Hi Goffredo,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on kdave/for-next]
[also build test WARNING on next-20210222]
[cannot apply to v5.11]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Goffredo-Baroncelli/btrfs-add-ioctl-BTRFS_IOC_DEV_PROPERTIES/20210223-062001
base:   https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next
config: i386-randconfig-r011-20210222 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/62c95ccebf2c45bb8e91d379b454dd720734da34
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Goffredo-Baroncelli/btrfs-add-ioctl-BTRFS_IOC_DEV_PROPERTIES/20210223-062001
        git checkout 62c95ccebf2c45bb8e91d379b454dd720734da34
        # save the attached .config to linux build tree
        make W=1 ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   fs/btrfs/ioctl.c: In function 'btrfs_ioctl_dev_properties':
>> fs/btrfs/ioctl.c:4923:1: warning: the frame size of 1036 bytes is larger than 1024 bytes [-Wframe-larger-than=]
    4923 | }
         | ^


vim +4923 fs/btrfs/ioctl.c

  4858	
  4859	static long btrfs_ioctl_dev_properties(struct file *file,
  4860							void __user *argp)
  4861	{
  4862		struct inode *inode = file_inode(file);
  4863		struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  4864		struct btrfs_ioctl_dev_properties dev_props;
  4865		struct btrfs_device	*device;
  4866		struct btrfs_root *root = fs_info->chunk_root;
  4867		struct btrfs_trans_handle *trans;
  4868		int ret;
  4869		u64 prev_type;
  4870	
  4871		if (!capable(CAP_SYS_ADMIN))
  4872			return -EPERM;
  4873	
  4874		if (copy_from_user(&dev_props, argp, sizeof(dev_props)))
  4875			return -EFAULT;
  4876	
  4877		device = btrfs_find_device(fs_info->fs_devices, dev_props.devid,
  4878					NULL, NULL);
  4879		if (!device) {
  4880			btrfs_info(fs_info, "change_dev_properties: unable to find device %llu",
  4881				   dev_props.devid);
  4882			return -ENODEV;
  4883		}
  4884	
  4885		if (dev_props.properties & BTRFS_DEV_PROPERTY_READ) {
  4886			u64 props = dev_props.properties;
  4887	
  4888			memset(&dev_props, 0, sizeof(dev_props));
  4889			if (props & BTRFS_DEV_PROPERTY_TYPE) {
  4890				dev_props.properties = BTRFS_DEV_PROPERTY_TYPE;
  4891				dev_props.type = device->type;
  4892			}
  4893			if (copy_to_user(argp, &dev_props, sizeof(dev_props)))
  4894				return -EFAULT;
  4895			return 0;
  4896		}
  4897	
  4898		/* it is possible to set only BTRFS_DEV_PROPERTY_TYPE for now */
  4899		if (dev_props.properties & ~(BTRFS_DEV_PROPERTY_TYPE))
  4900			return -EPERM;
  4901	
  4902		trans = btrfs_start_transaction(root, 1);
  4903		if (IS_ERR(trans))
  4904			return PTR_ERR(trans);
  4905	
  4906		prev_type = device->type;
  4907		device->type = dev_props.type;
  4908		ret = btrfs_update_device(trans, device);
  4909	
  4910		if (ret < 0) {
  4911			btrfs_abort_transaction(trans, ret);
  4912			btrfs_end_transaction(trans);
  4913			device->type = prev_type;
  4914			return  ret;
  4915		}
  4916	
  4917		ret = btrfs_commit_transaction(trans);
  4918		if (ret < 0)
  4919			device->type = prev_type;
  4920	
  4921		return ret;
  4922	
> 4923	}
  4924	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

[-- Attachment #2: .config.gz --]
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Re: [PATCH 1/4] btrfs: add ioctl BTRFS_IOC_DEV_PROPERTIES.

[David Sterba]

On Mon, Feb 22, 2021 at 10:19:06PM +0100, Goffredo Baroncelli wrote:
> From: Goffredo Baroncelli <kreijack@inwind.it>
> 
> This ioctl is a base for returning / setting information from / to  the
> fields of the btrfs_dev_item object.

Please don't add a new ioctl for properties, they're using the xattr as
interface alrady.

Re: [PATCH 1/4] btrfs: add ioctl BTRFS_IOC_DEV_PROPERTIES.

[Goffredo Baroncelli]

On 2/23/21 2:53 PM, David Sterba wrote:
> On Mon, Feb 22, 2021 at 10:19:06PM +0100, Goffredo Baroncelli wrote:
>> From: Goffredo Baroncelli <kreijack@inwind.it>
>>
>> This ioctl is a base for returning / setting information from / to  the
>> fields of the btrfs_dev_item object.

Hi David,

> 
> Please don't add a new ioctl for properties, they're using the xattr as
> interface alrady.
> how it is supposed to work with a device ?

I have to point out that the property is already exported in sysfs.
However I read a comment in sysfs code that discourages
to make a filesystem updating (open a new transaction) in the sysfs
handler. Do you have any suggestion ?

Thanks in advance
BR
Goffredo

-- 
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D  17B2 0EDA 9B37 8B82 E0B5

Re: [PATCH 1/4] btrfs: add ioctl BTRFS_IOC_DEV_PROPERTIES.

[Goffredo Baroncelli]

I resend it because I made a little mess with the quotation

On 2/23/21 6:59 PM, Goffredo Baroncelli wrote:
> On 2/23/21 2:53 PM, David Sterba wrote:
>> On Mon, Feb 22, 2021 at 10:19:06PM +0100, Goffredo Baroncelli wrote:
>>> From: Goffredo Baroncelli <kreijack@inwind.it>
>>>
>>> This ioctl is a base for returning / setting information from / to  the
>>> fields of the btrfs_dev_item object.
> 

Hi David,

> 
>>
>> Please don't add a new ioctl for properties, they're using the xattr as
>> interface alrady.

How it is supposed to work with a device ?
  
I have to point out that the property is already exported in sysfs.
However I read a comment in sysfs code that discourages
to make a filesystem updating (open a new transaction) in the sysfs
handler. Do you have any suggestion ?



> 
> Thanks in advance
> BR
> Goffredo
> 


-- 
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D  17B2 0EDA 9B37 8B82 E0B5

Re: [PATCH 1/4] btrfs: add ioctl BTRFS_IOC_DEV_PROPERTIES.

[Goffredo Baroncelli]

On 2/23/21 5:28 AM, kernel test robot wrote:
> Hi Goffredo,
> 
> Thank you for the patch! Perhaps something to improve:
> 
> [auto build test WARNING on kdave/for-next]
> [also build test WARNING on next-20210222]
> [cannot apply to v5.11]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch]
> 
> url:    https://github.com/0day-ci/linux/commits/Goffredo-Baroncelli/btrfs-add-ioctl-BTRFS_IOC_DEV_PROPERTIES/20210223-062001
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next
> config: i386-randconfig-r011-20210222 (attached as .config)
> compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
> reproduce (this is a W=1 build):
>          # https://github.com/0day-ci/linux/commit/62c95ccebf2c45bb8e91d379b454dd720734da34
>          git remote add linux-review https://github.com/0day-ci/linux
>          git fetch --no-tags linux-review Goffredo-Baroncelli/btrfs-add-ioctl-BTRFS_IOC_DEV_PROPERTIES/20210223-062001
>          git checkout 62c95ccebf2c45bb8e91d379b454dd720734da34
>          # save the attached .config to linux build tree
>          make W=1 ARCH=i386
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> 
> All warnings (new ones prefixed by >>):
> 
>     fs/btrfs/ioctl.c: In function 'btrfs_ioctl_dev_properties':
>>> fs/btrfs/ioctl.c:4923:1: warning: the frame size of 1036 bytes is larger than 1024 bytes [-Wframe-larger-than=]
>      4923 | }
>           | ^
> 
> 
> vim +4923 fs/btrfs/ioctl.c
> 
>    4858	
>    4859	static long btrfs_ioctl_dev_properties(struct file *file,
>    4860							void __user *argp)
>    4861	{
>    4862		struct inode *inode = file_inode(file);
>    4863		struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
>    4864		struct btrfs_ioctl_dev_properties dev_props;

Right, now that btrfs_ioctl_dev_properties is large 1k, it is not nice to store it in the stack...


>    4865		struct btrfs_device	*device;
>    4866		struct btrfs_root *root = fs_info->chunk_root;
>    4867		struct btrfs_trans_handle *trans;
>    4868		int ret;
>    4869		u64 prev_type;
>    4870	
>    4871		if (!capable(CAP_SYS_ADMIN))
>    4872			return -EPERM;
>    4873	
>    4874		if (copy_from_user(&dev_props, argp, sizeof(dev_props)))
>    4875			return -EFAULT;
>    4876	
>    4877		device = btrfs_find_device(fs_info->fs_devices, dev_props.devid,
>    4878					NULL, NULL);
>    4879		if (!device) {
>    4880			btrfs_info(fs_info, "change_dev_properties: unable to find device %llu",
>    4881				   dev_props.devid);
>    4882			return -ENODEV;
>    4883		}
>    4884	
>    4885		if (dev_props.properties & BTRFS_DEV_PROPERTY_READ) {
>    4886			u64 props = dev_props.properties;
>    4887	
>    4888			memset(&dev_props, 0, sizeof(dev_props));
>    4889			if (props & BTRFS_DEV_PROPERTY_TYPE) {
>    4890				dev_props.properties = BTRFS_DEV_PROPERTY_TYPE;
>    4891				dev_props.type = device->type;
>    4892			}
>    4893			if (copy_to_user(argp, &dev_props, sizeof(dev_props)))
>    4894				return -EFAULT;
>    4895			return 0;
>    4896		}
>    4897	
>    4898		/* it is possible to set only BTRFS_DEV_PROPERTY_TYPE for now */
>    4899		if (dev_props.properties & ~(BTRFS_DEV_PROPERTY_TYPE))
>    4900			return -EPERM;
>    4901	
>    4902		trans = btrfs_start_transaction(root, 1);
>    4903		if (IS_ERR(trans))
>    4904			return PTR_ERR(trans);
>    4905	
>    4906		prev_type = device->type;
>    4907		device->type = dev_props.type;
>    4908		ret = btrfs_update_device(trans, device);
>    4909	
>    4910		if (ret < 0) {
>    4911			btrfs_abort_transaction(trans, ret);
>    4912			btrfs_end_transaction(trans);
>    4913			device->type = prev_type;
>    4914			return  ret;
>    4915		}
>    4916	
>    4917		ret = btrfs_commit_transaction(trans);
>    4918		if (ret < 0)
>    4919			device->type = prev_type;
>    4920	
>    4921		return ret;
>    4922	
>> 4923	}
>    4924	
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
> 


-- 
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D  17B2 0EDA 9B37 8B82 E0B5

Re: [PATCH 1/4] btrfs: add ioctl BTRFS_IOC_DEV_PROPERTIES.

[Anand Jain]

On 23/02/2021 21:53, David Sterba wrote:
> On Mon, Feb 22, 2021 at 10:19:06PM +0100, Goffredo Baroncelli wrote:
>> From: Goffredo Baroncelli <kreijack@inwind.it>
>>
>> This ioctl is a base for returning / setting information from / to  the
>> fields of the btrfs_dev_item object.
> 
> Please don't add a new ioctl for properties, they're using the xattr as
> interface alrady.
> 

IMO a feature like this can be in memory only initially[1]. And later
when this feature is stable, add its on-disk.

[1] 
https://patchwork.kernel.org/project/linux-btrfs/patch/0ed770d6d5e37fc942f3034d917d2b38477d7d20.1613668002.git.anand.jain@oracle.com/


Thanks, Anand

Re: [PATCH 1/4] btrfs: add ioctl BTRFS_IOC_DEV_PROPERTIES.

[Zygo Blaxell]

On Wed, Feb 24, 2021 at 10:27:45AM +0800, Anand Jain wrote:
> On 23/02/2021 21:53, David Sterba wrote:
> > On Mon, Feb 22, 2021 at 10:19:06PM +0100, Goffredo Baroncelli wrote:
> > > From: Goffredo Baroncelli <kreijack@inwind.it>
> > > 
> > > This ioctl is a base for returning / setting information from / to  the
> > > fields of the btrfs_dev_item object.
> > 
> > Please don't add a new ioctl for properties, they're using the xattr as
> > interface alrady.
> > 
> 
> IMO a feature like this can be in memory only initially[1]. And later
> when this feature is stable, add its on-disk.

The "metadata_only" and "data_only" settings need to be persistent for
the feature to really work.

It is very expensive to recover (need to balance metadata on a spinning
disk) if the filesystem allocates a new chunk after mount but before
userspace can reestablish the preferences.  The whole point of
metadata_only and data_only is that we never have to do that.

> [1] https://patchwork.kernel.org/project/linux-btrfs/patch/0ed770d6d5e37fc942f3034d917d2b38477d7d20.1613668002.git.anand.jain@oracle.com/
> 
> 
> Thanks, Anand
> 

Re: [PATCH 1/4] btrfs: add ioctl BTRFS_IOC_DEV_PROPERTIES.

[Zygo Blaxell]

On Tue, Feb 23, 2021 at 02:53:30PM +0100, David Sterba wrote:
> On Mon, Feb 22, 2021 at 10:19:06PM +0100, Goffredo Baroncelli wrote:
> > From: Goffredo Baroncelli <kreijack@inwind.it>
> > 
> > This ioctl is a base for returning / setting information from / to  the
> > fields of the btrfs_dev_item object.
> 
> Please don't add a new ioctl for properties, they're using the xattr as
> interface alrady.

We had some earlier discussion about why xattrs on an inode are a
bad idea for this feature:

	https://lore.kernel.org/linux-btrfs/20210123172118.GJ28049@hungrycats.org/

TL;DR they shouldn't be copied from one filesystem to another.

Maybe it's better from a CLI UI point of view to put them under 'btrfs
dev' instead of 'btrfs property'?