fs_devices->latest_bdev = latest_dev->bdev;
fs_devices->total_rw_bytes = 0;
fs_devices->chunk_alloc_policy = BTRFS_CHUNK_ALLOC_REGULAR;
+ fs_devices->read_policy = BTRFS_READ_POLICY_PID;
return 0;
}
else
num_stripes = map->num_stripes;
- preferred_mirror = first + current->pid % num_stripes;
+ switch (fs_info->fs_devices->read_policy) {
+ default:
+ /* Shouldn't happen, just warn and use pid instead of failing */
+ btrfs_warn_rl(fs_info,
+ "unknown read_policy type %u, reset to pid",
+ fs_info->fs_devices->read_policy);
+ fs_info->fs_devices->read_policy = BTRFS_READ_POLICY_PID;
+ fallthrough;
+ case BTRFS_READ_POLICY_PID:
+ preferred_mirror = first + (current->pid % num_stripes);
+ break;
+ }
if (dev_replace_is_ongoing &&
fs_info->dev_replace.cont_reading_from_srcdev_mode ==
BTRFS_CHUNK_ALLOC_REGULAR,
};
+/*
+ * Read policies for mirrored block group profiles, read picks the stripe based
+ * on these policies.
+ */
+enum btrfs_read_policy {
+ /* Use process PID to choose the stripe */
+ BTRFS_READ_POLICY_PID,
+ BTRFS_NR_READ_POLICY,
+};
+
struct btrfs_fs_devices {
u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
u8 metadata_uuid[BTRFS_FSID_SIZE];
struct completion kobj_unregister;
enum btrfs_chunk_allocation_policy chunk_alloc_policy;
+
+ /* Policy used to read the mirrored stripes */
+ enum btrfs_read_policy read_policy;
};
#define BTRFS_BIO_INLINE_CSUM_SIZE 64