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From: Anand Jain <anand.jain@oracle.com>
To: linux-btrfs@vger.kernel.org
Cc: josef@toxicpanda.com, dsterba@suse.cz
Subject: [PATCH v6 4/5] btrfs: introduce new device-state read_preferred
Date: Wed, 19 Feb 2020 19:29:25 +0800	[thread overview]
Message-ID: <1582111766-8372-5-git-send-email-anand.jain@oracle.com> (raw)
In-Reply-To: <1582111766-8372-1-git-send-email-anand.jain@oracle.com>

Provides a sysfs interface to set the device state as read_preferred.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
v6: If there is no change in device's read prefer then don't log.
    Add pid to the logs.
v5: born

 fs/btrfs/sysfs.c   | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/volumes.h |  1 +
 2 files changed, 56 insertions(+)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index c9a8850b186a..72daaedb7b04 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -1317,11 +1317,66 @@ 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 ed2bba741b6e..07962a0ce898 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -52,6 +52,7 @@ struct btrfs_io_geometry {
 #define BTRFS_DEV_STATE_MISSING		(2)
 #define BTRFS_DEV_STATE_REPLACE_TGT	(3)
 #define BTRFS_DEV_STATE_FLUSH_SENT	(4)
+#define BTRFS_DEV_STATE_READ_PREFERRED	(5)
 
 struct btrfs_device {
 	struct list_head dev_list; /* device_list_mutex */
-- 
1.8.3.1


  parent reply	other threads:[~2020-02-19 11:29 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-19 11:29 [PATCH v6 0/5] readmirror feature (sysfs and in-memory only approach; with new read_policy device) Anand Jain
2020-02-19 11:29 ` [PATCH v6 1/5] btrfs: add btrfs_strmatch helper Anand Jain
2020-02-19 11:29 ` [PATCH v6 2/5] btrfs: create read policy framework Anand Jain
2020-02-19 11:29 ` [PATCH v6 3/5] btrfs: create read policy sysfs attribute, pid Anand Jain
2020-02-19 11:29 ` Anand Jain [this message]
2020-02-19 11:29 ` [PATCH v6 5/5] btrfs: introduce new read_policy device Anand Jain
2020-02-19 12:18   ` Steven Davies
2020-02-20  3:54     ` Anand Jain

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