Hi
This is the second version of the patch. Alasdair pointed out that when
the ioctl returns an error, the userspace is not supposed to parse the
dm_ioctl structure - there would be confusion because some paths return
the error in the "name" field and some don't.
So I reworked the patch so that it puts the error to the "name" field,
puts the error code to the "error" field (it used to be "padding") and it
returns zero.
Mikulas
dm-ioctl: make an option to return an error string
Add a possibility to return an error string to userspace. We introduce a
new flag DM_RETURN_ERROR_FLAG. This flag should be set on table load
ioctl. When this flag is present and table load fails, we return the error
string in the "name" field of the ioctl and the error code in the "error"
field. The flag DM_RETURN_ERROR_FLAG will be cleared and the ioctl returns
0.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Index: linux-2.6/drivers/md/dm-ioctl.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-ioctl.c
+++ linux-2.6/drivers/md/dm-ioctl.c
@@ -1377,7 +1377,8 @@ static int next_target(struct dm_target_
}
static int populate_table(struct dm_table *table,
- struct dm_ioctl *param, size_t param_size)
+ struct dm_ioctl *param, size_t param_size,
+ char **ti_error)
{
int r;
unsigned int i = 0;
@@ -1388,6 +1389,8 @@ static int populate_table(struct dm_tabl
if (!param->target_count) {
DMWARN("populate_table: no targets specified");
+ if (ti_error)
+ *ti_error = "no targets specified";
return -EINVAL;
}
@@ -1396,13 +1399,15 @@ static int populate_table(struct dm_tabl
r = next_target(spec, next, end, &spec, &target_params);
if (r) {
DMWARN("unable to find target");
+ if (ti_error)
+ *ti_error = "unable to find target";
return r;
}
r = dm_table_add_target(table, spec->target_type,
(sector_t) spec->sector_start,
(sector_t) spec->length,
- target_params);
+ target_params, ti_error);
if (r) {
DMWARN("error adding target to table");
return r;
@@ -1430,18 +1435,24 @@ static int table_load(struct file *filp,
struct dm_table *t, *old_map = NULL;
struct mapped_device *md;
struct target_type *immutable_target_type;
+ char *ti_error;
md = find_device(param);
- if (!md)
- return -ENXIO;
+ if (!md) {
+ r = -ENXIO;
+ ti_error = "unable to find device";
+ goto err0;
+ }
r = dm_table_create(&t, get_mode(param), param->target_count, md);
- if (r)
+ if (r) {
+ ti_error = "unable to create table";
goto err;
+ }
/* Protect md->type and md->queue against concurrent table loads. */
dm_lock_md_type(md);
- r = populate_table(t, param, param_size);
+ r = populate_table(t, param, param_size, &ti_error);
if (r)
goto err_unlock_md_type;
@@ -1454,6 +1465,7 @@ static int table_load(struct file *filp,
DMWARN("can't replace immutable target type %s",
immutable_target_type->name);
r = -EINVAL;
+ ti_error = "can't replace immutable target";
goto err_unlock_md_type;
}
@@ -1462,12 +1474,14 @@ static int table_load(struct file *filp,
r = dm_setup_md_queue(md, t);
if (r) {
DMWARN("unable to set up device queue for new table.");
+ ti_error = "unable to set up device queue for new table";
goto err_unlock_md_type;
}
} else if (!is_valid_type(dm_get_md_type(md), dm_table_get_type(t))) {
DMWARN("can't change device type (old=%u vs new=%u) after initial table load.",
dm_get_md_type(md), dm_table_get_type(t));
r = -EINVAL;
+ ti_error = "can't change device type after initial table load";
goto err_unlock_md_type;
}
@@ -1480,6 +1494,7 @@ static int table_load(struct file *filp,
DMWARN("device has been removed from the dev hash table.");
up_write(&_hash_lock);
r = -ENXIO;
+ ti_error = "device has been removed from the dev hash table";
goto err_destroy_table;
}
@@ -1506,7 +1521,13 @@ err_destroy_table:
dm_table_destroy(t);
err:
dm_put(md);
-
+err0:
+ if (param->flags & DM_RETURN_ERROR_FLAG) {
+ param->flags &= ~DM_RETURN_ERROR_FLAG;
+ strlcpy(param->name, ti_error, sizeof param->name);
+ param->error = r;
+ return 0;
+ }
return r;
}
@@ -1919,6 +1940,9 @@ static int validate_params(uint cmd, str
param->flags &= ~DM_SECURE_DATA_FLAG;
param->flags &= ~DM_DATA_OUT_FLAG;
+ if (param->flags & DM_RETURN_ERROR_FLAG)
+ param->error = 0;
+
/* Ignores parameters */
if (cmd == DM_REMOVE_ALL_CMD ||
cmd == DM_LIST_DEVICES_CMD ||
@@ -2201,7 +2225,7 @@ int __init dm_early_create(struct dm_ioc
r = dm_table_add_target(t, spec_array[i]->target_type,
(sector_t) spec_array[i]->sector_start,
(sector_t) spec_array[i]->length,
- target_params_array[i]);
+ target_params_array[i], NULL);
if (r) {
DMWARN("error adding target to table");
goto err_destroy_table;
Index: linux-2.6/drivers/md/dm-table.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-table.c
+++ linux-2.6/drivers/md/dm-table.c
@@ -631,56 +631,58 @@ static int validate_hardware_logical_blo
}
int dm_table_add_target(struct dm_table *t, const char *type,
- sector_t start, sector_t len, char *params)
+ sector_t start, sector_t len, char *params,
+ char **ti_error)
{
int r = -EINVAL, argc;
char **argv;
struct dm_target *ti;
- if (t->singleton) {
- DMERR("%s: target type %s must appear alone in table",
- dm_device_name(t->md), t->targets->type->name);
- return -EINVAL;
- }
-
BUG_ON(t->num_targets >= t->num_allocated);
-
ti = t->targets + t->num_targets;
memset(ti, 0, sizeof(*ti));
+ if (t->singleton) {
+ ti->error = "singleton target must appear alone in table";
+ r = -EINVAL;
+ goto bad0;
+ }
+
if (!len) {
- DMERR("%s: zero-length target", dm_device_name(t->md));
- return -EINVAL;
+ ti->error = "zero-length target";
+ r = -EINVAL;
+ goto bad0;
}
ti->type = dm_get_target_type(type);
if (!ti->type) {
- DMERR("%s: %s: unknown target type", dm_device_name(t->md), type);
- return -EINVAL;
+ ti->error = "unknown target type";
+ r = -EINVAL;
+ goto bad0;
}
if (dm_target_needs_singleton(ti->type)) {
if (t->num_targets) {
ti->error = "singleton target type must appear alone in table";
- goto bad;
+ goto bad1;
}
t->singleton = true;
}
if (dm_target_always_writeable(ti->type) && !(t->mode & FMODE_WRITE)) {
ti->error = "target type may not be included in a read-only table";
- goto bad;
+ goto bad1;
}
if (t->immutable_target_type) {
if (t->immutable_target_type != ti->type) {
ti->error = "immutable target type cannot be mixed with other target types";
- goto bad;
+ goto bad1;
}
} else if (dm_target_is_immutable(ti->type)) {
if (t->num_targets) {
ti->error = "immutable target type cannot be mixed with other target types";
- goto bad;
+ goto bad1;
}
t->immutable_target_type = ti->type;
}
@@ -698,19 +700,19 @@ int dm_table_add_target(struct dm_table
*/
if (!adjoin(t, ti)) {
ti->error = "Gap in table";
- goto bad;
+ goto bad1;
}
r = dm_split_args(&argc, &argv, params);
if (r) {
ti->error = "couldn't split parameters";
- goto bad;
+ goto bad1;
}
r = ti->type->ctr(ti, argc, argv);
kfree(argv);
if (r)
- goto bad;
+ goto bad1;
t->highs[t->num_targets++] = ti->begin + ti->len - 1;
@@ -723,9 +725,12 @@ int dm_table_add_target(struct dm_table
return 0;
- bad:
- DMERR("%s: %s: %s (%pe)", dm_device_name(t->md), type, ti->error, ERR_PTR(r));
+bad1:
dm_put_target_type(ti->type);
+bad0:
+ DMERR("%s: %s: %s (%pe)", dm_device_name(t->md), type, ti->error, ERR_PTR(r));
+ if (ti_error)
+ *ti_error = ti->error;
return r;
}
Index: linux-2.6/include/linux/device-mapper.h
===================================================================
--- linux-2.6.orig/include/linux/device-mapper.h
+++ linux-2.6/include/linux/device-mapper.h
@@ -531,7 +531,8 @@ int dm_table_create(struct dm_table **re
* Then call this once for each target.
*/
int dm_table_add_target(struct dm_table *t, const char *type,
- sector_t start, sector_t len, char *params);
+ sector_t start, sector_t len, char *params,
+ char **ti_error);
/*
* Target can use this to set the table's type.
Index: linux-2.6/include/uapi/linux/dm-ioctl.h
===================================================================
--- linux-2.6.orig/include/uapi/linux/dm-ioctl.h
+++ linux-2.6/include/uapi/linux/dm-ioctl.h
@@ -136,7 +136,7 @@ struct dm_ioctl {
* For output, the ioctls return the event number, not the cookie.
*/
__u32 event_nr; /* in/out */
- __u32 padding;
+ __s32 error; /* out */
__u64 dev; /* in/out */
@@ -286,9 +286,9 @@ enum {
#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 47
+#define DM_VERSION_MINOR 48
#define DM_VERSION_PATCHLEVEL 0
-#define DM_VERSION_EXTRA "-ioctl (2022-07-28)"
+#define DM_VERSION_EXTRA "-ioctl (2022-08-24)"
/* Status bits */
#define DM_READONLY_FLAG (1 << 0) /* In/Out */
@@ -382,4 +382,12 @@ enum {
*/
#define DM_IMA_MEASUREMENT_FLAG (1 << 19) /* In */
+/*
+ * If this flag is set, the caller wants to receive the error string.
+ * The error string is returned in the "name" field of the ioctl and
+ * the error number is returned in the "error" field. The ioctl returns
+ * zero.
+ */
+#define DM_RETURN_ERROR_FLAG (1 << 20) /* In */
+
#endif /* _LINUX_DM_IOCTL_H */
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://listman.redhat.com/mailman/listinfo/dm-devel
