diff mbox series

[v3,2/4] btrfs: introduce new device-state read_preferred

Message ID 3f27d3da96accec05273a8ffc2a2d24554c78a1b.1610324448.git.anand.jain@oracle.com (mailing list archive)
State New, archived
Headers show
Series [v3,1/4] btrfs: add read_policy latency | expand

Commit Message

Anand Jain Jan. 11, 2021, 9:41 a.m. UTC
This is a preparatory patch and introduces a new device flag
'read_preferred', RW-able using sysfs interface.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
v2: C style fixes. Drop space in between '! test_bit' and extra lines
    after it.

 fs/btrfs/sysfs.c   | 53 ++++++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/volumes.h |  1 +
 2 files changed, 54 insertions(+)

Comments

Josef Bacik Jan. 19, 2021, 7:44 p.m. UTC | #1
On 1/11/21 4:41 AM, Anand Jain wrote:
> This is a preparatory patch and introduces a new device flag
> 'read_preferred', RW-able using sysfs interface.
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef
diff mbox series

Patch

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 96ca7bef6357..b5d6499fbad0 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -1417,11 +1417,64 @@  static ssize_t btrfs_devinfo_writeable_show(struct kobject *kobj,
 }
 BTRFS_ATTR(devid, writeable, btrfs_devinfo_writeable_show);
 
+static ssize_t btrfs_devinfo_read_pref_show(struct kobject *kobj,
+					    struct kobj_attribute *a, char *buf)
+{
+	int val;
+	struct btrfs_device *device = container_of(kobj, struct btrfs_device,
+						   devid_kobj);
+
+	val = !!test_bit(BTRFS_DEV_STATE_READ_PREFERRED, &device->dev_state);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", val);
+}
+
+static ssize_t btrfs_devinfo_read_pref_store(struct kobject *kobj,
+					     struct kobj_attribute *a,
+					     const char *buf, size_t len)
+{
+	int ret;
+	unsigned long val;
+	struct btrfs_device *device;
+
+	ret = kstrtoul(skip_spaces(buf), 0, &val);
+	if (ret)
+		return ret;
+
+	if (val != 0 && val != 1)
+		return -EINVAL;
+
+	/*
+	 * lock is not required, the btrfs_device struct can't be freed while
+	 * its kobject btrfs_device::devid_kobj is still open.
+	 */
+	device = container_of(kobj, struct btrfs_device, devid_kobj);
+
+	if (val &&
+	    !test_bit(BTRFS_DEV_STATE_READ_PREFERRED, &device->dev_state)) {
+		set_bit(BTRFS_DEV_STATE_READ_PREFERRED, &device->dev_state);
+		btrfs_info(device->fs_devices->fs_info,
+			   "set read preferred on devid %llu (%d)",
+			   device->devid, task_pid_nr(current));
+	} else if (!val &&
+		   test_bit(BTRFS_DEV_STATE_READ_PREFERRED, &device->dev_state)) {
+		clear_bit(BTRFS_DEV_STATE_READ_PREFERRED, &device->dev_state);
+		btrfs_info(device->fs_devices->fs_info,
+			   "reset read preferred on devid %llu (%d)",
+			   device->devid, task_pid_nr(current));
+	}
+
+	return len;
+}
+BTRFS_ATTR_RW(devid, read_preferred, btrfs_devinfo_read_pref_show,
+	      btrfs_devinfo_read_pref_store);
+
 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, read_preferred),
 	NULL
 };
 ATTRIBUTE_GROUPS(devid);
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 71ba1f0e93f4..ea786864b903 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -51,6 +51,7 @@  struct btrfs_io_geometry {
 #define BTRFS_DEV_STATE_REPLACE_TGT	(3)
 #define BTRFS_DEV_STATE_FLUSH_SENT	(4)
 #define BTRFS_DEV_STATE_NO_READA	(5)
+#define BTRFS_DEV_STATE_READ_PREFERRED	(6)
 
 struct btrfs_zoned_device_info;