This ioctl is added to trigger a readahead from user mode. It implements
a readahead using the new interface and also a traditional tree walk.
This way it's possible to measure the two side by side.
Signed-off-by: Arne Jansen <sensi...@gmx.net>
---
fs/btrfs/ioctl.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
fs/btrfs/ioctl.h | 16 ++++++++++
2 files changed, 101 insertions(+), 1 deletions(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index f580a3a..13a88d7 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2465,6 +2465,89 @@ static noinline long btrfs_ioctl_wait_sync(struct file
*file, void __user *argp)
return btrfs_wait_for_commit(root, transid);
}
+static noinline long btrfs_ioctl_reada_test(struct btrfs_fs_info *fs_info,
+ void __user *argp)
+{
+ struct btrfs_key start = {0, 0, 0};
+ struct btrfs_key end = {(u64)-1ll, (u8)-1, (u64)-1ll};
+ struct btrfs_ioctl_reada_args reada_args;
+ struct btrfs_key key;
+ struct btrfs_root *root = NULL;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (!argp)
+ return -EINVAL;
+
+ if (copy_from_user(&reada_args,
+ (struct btrfs_ioctl_reada_args __user *)argp,
+ sizeof(reada_args)))
+ return -EFAULT;
+
+ start.objectid = reada_args.start_objectid;
+ start.type = reada_args.start_type;
+ start.offset = reada_args.start_offset;
+ end.objectid = reada_args.end_objectid;
+ end.type = reada_args.end_type;
+ end.offset = reada_args.end_offset;
+
+ key.objectid = reada_args.tree;
+ key.type = BTRFS_ROOT_ITEM_KEY;
+ key.offset = (u64)-1;
+ root = btrfs_read_fs_root_no_name(fs_info, &key);
+ if (IS_ERR(root))
+ return -ENOENT;
+
+ if (!(reada_args.flags & BTRFS_READA_IOC_FLAGS_TRAD)) {
+ void *handle;
+
+ handle = btrfs_reada_add(root, &start, &end);
+ if (IS_ERR(handle))
+ return PTR_ERR(handle);
+
+ if (reada_args.flags & BTRFS_READA_IOC_FLAGS_WAIT)
+ btrfs_reada_wait(handle);
+ else
+ btrfs_reada_detach(handle);
+ } else {
+ struct btrfs_path *path;
+ struct extent_buffer *leaf;
+ int slot;
+ int ret;
+
+ /*
+ * enumerate the tree the traditional way
+ */
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+ path->reada = 2;
+
+ ret = btrfs_search_slot(NULL, root, &start, path, 0, 0);
+ if (ret < 0)
+ goto out;
+
+ do {
+ leaf = path->nodes[0];
+ slot = path->slots[0];
+ btrfs_item_key_to_cpu(leaf, &key, slot);
+
+ if (key.objectid > end.objectid)
+ break;
+ if (key.objectid == end.objectid && key.type > end.type)
+ break;
+ if (key.objectid == end.objectid &&
+ key.type == end.type && key.offset > end.offset)
+ break;
+ } while ((ret = btrfs_next_leaf(root, path)) == 0);
+out:
+ btrfs_free_path(path);
+ return ret >= 0 ? 0 : ret;
+ }
+ return 0;
+}
+
long btrfs_ioctl(struct file *file, unsigned int
cmd, unsigned long arg)
{
@@ -2527,7 +2610,8 @@ long btrfs_ioctl(struct file *file, unsigned int
return btrfs_ioctl_start_sync(file, argp);
case BTRFS_IOC_WAIT_SYNC:
return btrfs_ioctl_wait_sync(file, argp);
+ case BTRFS_IOC_READA_TEST:
+ return btrfs_ioctl_reada_test(root->fs_info, argp);
}
-
return -ENOTTY;
}
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index 8fb3821..9c744ce 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -157,6 +157,20 @@ struct btrfs_ioctl_space_args {
struct btrfs_ioctl_space_info spaces[0];
};
+#define BTRFS_READA_IOC_FLAGS_WAIT 1
+#define BTRFS_READA_IOC_FLAGS_TRAD 2
+struct btrfs_ioctl_reada_args {
+ __u64 flags;
+ __u64 tree;
+ __u64 start_objectid;
+ __u8 start_type;
+ __u64 start_offset;
+ __u64 end_objectid;
+ __u8 end_type;
+ __u64 end_offset;
+ __u64 unused[100];
+};
+
#define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \
struct btrfs_ioctl_vol_args)
#define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, \
@@ -203,4 +217,6 @@ struct btrfs_ioctl_space_args {
struct btrfs_ioctl_vol_args_v2)
#define BTRFS_IOC_SUBVOL_GETFLAGS _IOW(BTRFS_IOCTL_MAGIC, 25, __u64)
#define BTRFS_IOC_SUBVOL_SETFLAGS _IOW(BTRFS_IOCTL_MAGIC, 26, __u64)
+#define BTRFS_IOC_READA_TEST _IOW(BTRFS_IOCTL_MAGIC, 99, \
+ struct btrfs_ioctl_reada_args)
#endif
--
1.7.3.4
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
