diff mbox series

[RFC,3/5] btrfs: add readmirror devid property

Message ID 1552989624-29577-4-git-send-email-anand.jain@oracle.com (mailing list archive)
State New, archived
Headers show
Series readmirror feature | expand

Commit Message

Anand Jain March 19, 2019, 10 a.m. UTC 
Introduces devid readmirror property, which directs all read IO to a
device.

For example:
  btrfs property set <mnt> readmirror devid<n>

As of now readmirror by devid supports only raid1s. Raid10 support has
to leverage device grouping feature to facilitate the setting of
readmirror by device set.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/props.c   | 49 ++++++++++++++++++++++++++++++++++++++++++++++---
 fs/btrfs/volumes.c | 16 ++++++++++++++++
 fs/btrfs/volumes.h |  3 +++
 3 files changed, 65 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/fs/btrfs/props.c b/fs/btrfs/props.c
index 776cdf099f93..a17c5a69bcb3 100644
--- a/fs/btrfs/props.c
+++ b/fs/btrfs/props.c
@@ -338,8 +338,28 @@  static int prop_readmirror_validate(struct inode *inode, const char *value,
 	if (!len)
 		return 0;
 
-	if (!strncmp("pid", value, 3))
+	if (!strncmp("pid", value, 3)) {
 		return 0;
+	} else if (!strncmp("devid", value, 5)) {
+		u64 devid;
+		char *value_dup;
+
+		if (len <= 5)
+			return -EINVAL;
+
+		value_dup = kstrndup(value, len, GFP_KERNEL);
+		if (!value_dup)
+			return -ENOMEM;
+		if (kstrtoull(value_dup + 5, 10, &devid)) {
+			kfree(value_dup);
+			return -EINVAL;
+		}
+		kfree(value_dup);
+
+		if (btrfs_find_device(root->fs_info->fs_devices, devid,
+				      NULL, NULL, false))
+			return 0;
+	}
 
 	return -EINVAL;
 }
@@ -349,10 +369,33 @@  static int prop_readmirror_apply(struct inode *inode, const char *value,
 {
 	struct btrfs_fs_devices *fs_devices = btrfs_sb(inode->i_sb)->fs_devices;
 
-	if (!value)
+	if (!value) {
 		fs_devices->readmirror_policy = BTRFS_READMIRROR_DEFAULT;
-	else if (!strncmp("pid", value, 3))
+	} else if (!strncmp("pid", value, 3)) {
 		fs_devices->readmirror_policy = BTRFS_READMIRROR_PID;
+	} else if (!strncmp("devid", value, 5)) {
+		u64 devid;
+		char *value_dup;
+		struct btrfs_device *device;
+		struct btrfs_root *root = BTRFS_I(inode)->root;
+
+		value_dup = kstrndup(value, len, GFP_KERNEL);
+		if (!value_dup)
+			return -ENOMEM;
+		if (kstrtoull(value_dup + 5, 10, &devid)) {
+			kfree(value_dup);
+			return -EINVAL;
+		}
+		kfree(value_dup);
+
+		fs_devices->readmirror_policy = BTRFS_READMIRROR_DEVID;
+		device = btrfs_find_device(root->fs_info->fs_devices, devid,
+					   NULL, NULL, false);
+		if (!device)
+			return -ENODEV;
+
+		device->type = BTRFS_DEVICE_TYPE_READ_OPTIMIZED;
+	}
 
 	return 0;
 }
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index e5072d46e181..d3b7427d6d96 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -5553,6 +5553,7 @@  static int find_live_mirror(struct btrfs_fs_info *fs_info,
 	int preferred_mirror;
 	int tolerance;
 	struct btrfs_device *srcdev;
+	bool found = false;
 
 	ASSERT((map->type &
 		 (BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID10)));
@@ -5563,6 +5564,21 @@  static int find_live_mirror(struct btrfs_fs_info *fs_info,
 		num_stripes = map->num_stripes;
 
 	switch(fs_info->fs_devices->readmirror_policy) {
+	case BTRFS_READMIRROR_DEVID:
+		/* skip raid10 for now */
+		if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
+			for (i = first; i < first + num_stripes; i++) {
+				if (map->stripes[i].dev->type ==
+				    BTRFS_DEVICE_TYPE_READ_OPTIMIZED) {
+					preferred_mirror = i;
+					found = true;
+					break;
+				}
+			}
+			if (found)
+				break;
+		}
+		/* fall through */
 	case BTRFS_READMIRROR_PID:
 		/* fall through */
 	case BTRFS_READMIRROR_DEFAULT:
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 27dce9242b55..9c2e64548a11 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -208,9 +208,12 @@  struct btrfs_device {
 BTRFS_DEVICE_GETSET_FUNCS(disk_total_bytes);
 BTRFS_DEVICE_GETSET_FUNCS(bytes_used);
 
+#define BTRFS_DEVICE_TYPE_READ_OPTIMIZED  1ULL
+
 enum btrfs_readmirror_policy {
 	BTRFS_READMIRROR_DEFAULT,
 	BTRFS_READMIRROR_PID,
+	BTRFS_READMIRROR_DEVID,
 };
 
 struct btrfs_fs_devices {