dm ioctl: optimize functions without variable params
Device-mapper ioctls receive and send data in a buffer supplied
by userspace. The buffer has two parts. The first part contains
a 'struct dm_ioctl' and has a fixed size. The second part depends
on the ioctl and has a variable size.
This patch recognises the specific ioctls that do not use the variable
part of the buffer and skips allocating memory for it.
In particular, when a device is suspended and a resume ioctl is sent,
this now avoid memory allocation completely.
The variable "struct dm_ioctl tmp" is moved from the function
copy_params to its caller ctl_ioctl and renamed to param_kernel.
It is used directly when the ioctl function doesn't need any arguments.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 9ae11b2..7eb0682 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1560,7 +1560,8 @@
return r;
}
-#define DM_PARAMS_VMALLOC 0x0001 /* Params alloced with vmalloc not kmalloc */
+#define DM_PARAMS_KMALLOC 0x0001 /* Params alloced with kmalloc */
+#define DM_PARAMS_VMALLOC 0x0002 /* Params alloced with vmalloc */
#define DM_WIPE_BUFFER 0x0010 /* Wipe input buffer before returning from ioctl */
static void free_params(struct dm_ioctl *param, size_t param_size, int param_flags)
@@ -1568,66 +1569,80 @@
if (param_flags & DM_WIPE_BUFFER)
memset(param, 0, param_size);
+ if (param_flags & DM_PARAMS_KMALLOC)
+ kfree(param);
if (param_flags & DM_PARAMS_VMALLOC)
vfree(param);
- else
- kfree(param);
}
-static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl **param, int *param_flags)
+static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kernel,
+ int ioctl_flags,
+ struct dm_ioctl **param, int *param_flags)
{
- struct dm_ioctl tmp, *dmi;
+ struct dm_ioctl *dmi;
int secure_data;
+ const size_t minimum_data_size = sizeof(*param_kernel) - sizeof(param_kernel->data);
- if (copy_from_user(&tmp, user, sizeof(tmp) - sizeof(tmp.data)))
+ if (copy_from_user(param_kernel, user, minimum_data_size))
return -EFAULT;
- if (tmp.data_size < (sizeof(tmp) - sizeof(tmp.data)))
+ if (param_kernel->data_size < minimum_data_size)
return -EINVAL;
- secure_data = tmp.flags & DM_SECURE_DATA_FLAG;
+ secure_data = param_kernel->flags & DM_SECURE_DATA_FLAG;
*param_flags = secure_data ? DM_WIPE_BUFFER : 0;
+ if (ioctl_flags & IOCTL_FLAGS_NO_PARAMS) {
+ dmi = param_kernel;
+ dmi->data_size = minimum_data_size;
+ goto data_copied;
+ }
+
/*
* Try to avoid low memory issues when a device is suspended.
* Use kmalloc() rather than vmalloc() when we can.
*/
dmi = NULL;
- if (tmp.data_size <= KMALLOC_MAX_SIZE)
- dmi = kmalloc(tmp.data_size, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
-
- if (!dmi) {
- dmi = __vmalloc(tmp.data_size, GFP_NOIO | __GFP_REPEAT | __GFP_HIGH, PAGE_KERNEL);
- *param_flags |= DM_PARAMS_VMALLOC;
+ if (param_kernel->data_size <= KMALLOC_MAX_SIZE) {
+ dmi = kmalloc(param_kernel->data_size, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
+ if (dmi)
+ *param_flags |= DM_PARAMS_KMALLOC;
}
if (!dmi) {
- if (secure_data && clear_user(user, tmp.data_size))
+ dmi = __vmalloc(param_kernel->data_size, GFP_NOIO | __GFP_REPEAT | __GFP_HIGH, PAGE_KERNEL);
+ if (dmi)
+ *param_flags |= DM_PARAMS_VMALLOC;
+ }
+
+ if (!dmi) {
+ if (secure_data && clear_user(user, param_kernel->data_size))
return -EFAULT;
return -ENOMEM;
}
- if (copy_from_user(dmi, user, tmp.data_size))
+ if (copy_from_user(dmi, user, param_kernel->data_size))
goto bad;
+data_copied:
/*
* Abort if something changed the ioctl data while it was being copied.
*/
- if (dmi->data_size != tmp.data_size) {
+ if (dmi->data_size != param_kernel->data_size) {
DMERR("rejecting ioctl: data size modified while processing parameters");
goto bad;
}
/* Wipe the user buffer so we do not return it to userspace */
- if (secure_data && clear_user(user, tmp.data_size))
+ if (secure_data && clear_user(user, param_kernel->data_size))
goto bad;
*param = dmi;
return 0;
bad:
- free_params(dmi, tmp.data_size, *param_flags);
+ free_params(dmi, param_kernel->data_size, *param_flags);
return -EFAULT;
}
@@ -1671,6 +1686,7 @@
struct dm_ioctl *uninitialized_var(param);
ioctl_fn fn = NULL;
size_t input_param_size;
+ struct dm_ioctl param_kernel;
/* only root can play with this */
if (!capable(CAP_SYS_ADMIN))
@@ -1704,7 +1720,7 @@
/*
* Copy the parameters into kernel space.
*/
- r = copy_params(user, ¶m, ¶m_flags);
+ r = copy_params(user, ¶m_kernel, ioctl_flags, ¶m, ¶m_flags);
if (r)
return r;
diff --git a/include/uapi/linux/dm-ioctl.h b/include/uapi/linux/dm-ioctl.h
index 539b179..b8a6bdd 100644
--- a/include/uapi/linux/dm-ioctl.h
+++ b/include/uapi/linux/dm-ioctl.h
@@ -267,9 +267,9 @@
#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
#define DM_VERSION_MAJOR 4
-#define DM_VERSION_MINOR 23
-#define DM_VERSION_PATCHLEVEL 1
-#define DM_VERSION_EXTRA "-ioctl (2012-12-18)"
+#define DM_VERSION_MINOR 24
+#define DM_VERSION_PATCHLEVEL 0
+#define DM_VERSION_EXTRA "-ioctl (2013-01-15)"
/* Status bits */
#define DM_READONLY_FLAG (1 << 0) /* In/Out */