# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1257795614 0
# Node ID 94c3f3d4b864bf74801bffb384d7354142850709
# Parent f6091947ffed5707b60120fe44d3d038a3307591
blktap2: configurable driver chains
Blktap2 allows block device drivers to be layered to create more
advanced virtual block devices. However, composing a layered driver is
not exposed to the user. This patch fixes this, and allows the user to
explicitly specify a driver chain when starting a tapdisk process,
using the pipe character ('|') to explicitly seperate layers in a
blktap2 configuration string.
for example, the command:
~$ tapdisk2 -n "log:|aio:/path/to/file.img"
will create a blktap2 device where read and write requests are passed
to the 'log' driver, then forwarded to the 'aio' driver.
Signed-off-by: Ryan O'Connor <rjo@xxxxxxxxx>
---
tools/blktap2/drivers/tapdisk-vbd.c | 248 +++++++++++++++++++++++++++++-------
tools/blktap2/drivers/tapdisk-vbd.h | 10 +
tools/blktap2/drivers/tapdisk2.c | 7 +
tools/blktap2/include/list.h | 20 ++
4 files changed, 238 insertions(+), 47 deletions(-)
diff -r f6091947ffed -r 94c3f3d4b864 tools/blktap2/drivers/tapdisk-vbd.c
--- a/tools/blktap2/drivers/tapdisk-vbd.c Mon Nov 09 19:19:27 2009 +0000
+++ b/tools/blktap2/drivers/tapdisk-vbd.c Mon Nov 09 19:40:14 2009 +0000
@@ -106,6 +106,7 @@ tapdisk_vbd_initialize(int rfd, int wfd,
vbd->callback = tapdisk_vbd_callback;
vbd->argument = vbd;
+ INIT_LIST_HEAD(&vbd->driver_stack);
INIT_LIST_HEAD(&vbd->images);
INIT_LIST_HEAD(&vbd->new_requests);
INIT_LIST_HEAD(&vbd->pending_requests);
@@ -541,6 +542,105 @@ regerr:
goto out;
}
+/* TODO: ugh, lets not call it parent info... */
+static struct list_head *
+tapdisk_vbd_open_level(td_vbd_t *vbd, char* params, int driver_type,
td_disk_info_t *parent_info, td_flag_t flags)
+{
+ char *name;
+ int type, err;
+ td_image_t *image;
+ td_disk_id_t id;
+ struct list_head *images;
+ td_driver_t *driver;
+
+ images = calloc(1, sizeof(struct list_head));
+ INIT_LIST_HEAD(images);
+
+ name = params;
+ type = driver_type;
+
+ for (;;) {
+ err = -ENOMEM;
+ image = tapdisk_image_allocate(name, type,
+ vbd->storage, flags, vbd);
+
+ /* free 'name' if it was created by td_get_parent_id() */
+ if (name != params) {
+ free(name);
+ name = NULL;
+ }
+
+ if (!image)
+ return NULL;
+
+
+ /* We have to do this to set the driver info for child drivers.
this conflicts with td_open */
+ driver = image->driver;
+ if (!driver) {
+ driver = tapdisk_driver_allocate(image->type,
+ image->name,
+ image->flags,
+ image->storage);
+ if (!driver)
+ return NULL;
+ }
+ /* the image has a driver, set the info and driver */
+ image->driver = driver;
+ image->info = driver->info;
+
+ /* XXX: we don't touch driver->refcount, broken? */
+ /* XXX: we've replicated about 90% of td_open() gross! */
+ /* XXX: this breaks if a driver modifies its info within a
layer */
+
+ /* if the parent info is set, pass it to the child */
+ if(parent_info)
+ {
+ image->driver->info = *parent_info;
+ }
+
+ err = td_load(image);
+ if (err) {
+ if (err != -ENODEV)
+ return NULL;
+
+ err = td_open(image);
+ if (err)
+ return NULL;
+ }
+
+ /* TODO: non-sink drivers that don't care about their child
+ * currently return EINVAL. Could return TD_PARENT_OK or
+ * TD_ANY_PARENT */
+
+ err = td_get_parent_id(image, &id);
+ if (err && (err != TD_NO_PARENT && err != -EINVAL)) {
+ td_close(image);
+ return NULL;
+ }
+
+ if (!image->storage)
+ image->storage = vbd->storage;
+
+ /* add this image to the end of the list */
+ list_add_tail(&image->next, images);
+
+ image = NULL;
+
+ /* if the image does not have a parent we return the
+ * list of images generated by this level of the stack */
+ if (err == TD_NO_PARENT || err == -EINVAL)
+ break;
+
+ name = id.name;
+ type = id.drivertype;
+#if 0
+ /* catch this by validate, not here */
+ flags |= (TD_OPEN_RDONLY | TD_OPEN_SHAREABLE);
+#endif
+ }
+ return images;
+}
+
static int
__tapdisk_vbd_open_vdi(td_vbd_t *vbd, td_flag_t extra_flags)
{
@@ -548,58 +648,35 @@ __tapdisk_vbd_open_vdi(td_vbd_t *vbd, td
int err, type;
td_flag_t flags;
td_disk_id_t id;
- td_image_t *image, *tmp;
+ td_image_t *tmp;
struct tfilter *filter = NULL;
+ td_vbd_driver_info_t *driver_info;
+ struct list_head *images;
+ td_disk_info_t *parent_info = NULL;
err = tapdisk_vbd_reactivate_volumes(vbd, 0);
if (err)
return err;
flags = (vbd->flags & ~TD_OPEN_SHAREABLE) | extra_flags;
- file = vbd->name;
- type = vbd->type;
-
- for (;;) {
- err = -ENOMEM;
- image = tapdisk_image_allocate(file, type,
- vbd->storage, flags, vbd);
-
- if (file != vbd->name) {
- free(file);
- file = NULL;
- }
-
- if (!image)
- goto fail;
-
- err = td_load(image);
- if (err) {
- if (err != -ENODEV)
- goto fail;
-
- err = td_open(image);
- if (err)
- goto fail;
- }
-
- err = td_get_parent_id(image, &id);
- if (err && err != TD_NO_PARENT) {
- td_close(image);
- goto fail;
- }
-
- if (!image->storage)
- image->storage = vbd->storage;
-
- tapdisk_vbd_add_image(vbd, image);
- image = NULL;
-
- if (err == TD_NO_PARENT)
- break;
-
- file = id.name;
- type = id.drivertype;
- flags |= (TD_OPEN_RDONLY | TD_OPEN_SHAREABLE);
+
+ /* loop on each user specified driver.
+ * NOTE: driver_info is in reverse order. That is, the first
+ * item is the 'parent' or 'sink' driver */
+ list_for_each_entry(driver_info, &vbd->driver_stack, next) {
+ file = driver_info->params;
+ type = driver_info->type;
+ images = tapdisk_vbd_open_level(vbd, file, type, parent_info,
flags);
+ if (!images)
+ return -EINVAL;
+
+ /* after each loop, append the created stack to the result
stack */
+ list_splice(images, &vbd->images);
+ free(images);
+
+ /* set the parent_info to the first diskinfo on the stack */
+ tmp = tapdisk_vbd_first_image(vbd);
+ parent_info = &tmp->info;
}
if (td_flag_test(vbd->flags, TD_OPEN_LOG_DIRTY)) {
@@ -623,11 +700,88 @@ __tapdisk_vbd_open_vdi(td_vbd_t *vbd, td
return 0;
fail:
+
+/* TODO: loop over vbd to free images? maybe do that in vbd_close_vdi */
+#if 0
if (image)
tapdisk_image_free(image);
-
+#endif
+
+ /* TODO: handle partial stack creation? */
tapdisk_vbd_close_vdi(vbd);
+ return err;
+}
+
+/* this populates a vbd type based on path */
+int
+tapdisk_vbd_parse_stack(td_vbd_t *vbd, const char *path)
+{
+ int err;
+ char *params, *driver_str;
+ td_vbd_driver_info_t *driver;
+
+ /* make a copy of path */
+ /* TODO: check against MAX_NAME_LEM ? */
+ err = tapdisk_namedup(¶ms, path);
+ if(err)
+ goto error;
+
+
+ /* tokenize params based on pipe '|' */
+ driver_str = strtok(params, "|");
+ while(driver_str != NULL)
+ {
+ /* parse driver info and add to vbd */
+ driver = calloc(1, sizeof(td_vbd_driver_info_t));
+ INIT_LIST_HEAD(&driver->next);
+ err = tapdisk_parse_disk_type(driver_str, &driver->params,
&driver->type);
+ if(err)
+ goto error;
+
+ /* build the list backwards as the last driver will be the first
+ * driver to open in the stack */
+ list_add(&driver->next, &vbd->driver_stack);
+
+ /* get next driver string */
+ driver_str = strtok(NULL, "|");
+ }
+
+ return 0;
+
+ /* error: free any driver_info's and params */
+ error:
+ while(!list_empty(&vbd->driver_stack)) {
+ driver = list_entry(vbd->driver_stack.next,
td_vbd_driver_info_t, next);
+ list_del(&driver->next);
+ free(driver);
+ }
+
+ return err;
+}
+
+/* NOTE: driver type, etc. must be set */
+static int
+tapdisk_vbd_open_stack(td_vbd_t *vbd, uint16_t storage, td_flag_t flags)
+{
+ int i, err;
+
+ vbd->flags = flags;
+ vbd->storage = storage;
+
+ for (i = 0; i < TD_VBD_EIO_RETRIES; i++) {
+ err = __tapdisk_vbd_open_vdi(vbd, 0);
+ if (err != -EIO)
+ break;
+
+ sleep(TD_VBD_EIO_SLEEP);
+ }
+ if (err)
+ goto fail;
+
+ return 0;
+
+ fail:
return err;
}
@@ -759,7 +913,7 @@ tapdisk_vbd_open(td_vbd_t *vbd, const ch
{
int err;
- err = tapdisk_vbd_open_vdi(vbd, name, type, storage, flags);
+ err = tapdisk_vbd_open_stack(vbd, storage, flags);
if (err)
goto out;
diff -r f6091947ffed -r 94c3f3d4b864 tools/blktap2/drivers/tapdisk-vbd.h
--- a/tools/blktap2/drivers/tapdisk-vbd.h Mon Nov 09 19:19:27 2009 +0000
+++ b/tools/blktap2/drivers/tapdisk-vbd.h Mon Nov 09 19:40:14 2009 +0000
@@ -53,6 +53,7 @@
typedef struct td_ring td_ring_t;
typedef struct td_vbd_request td_vbd_request_t;
+typedef struct td_vbd_driver_info td_vbd_driver_info_t;
typedef struct td_vbd_handle td_vbd_t;
typedef void (*td_vbd_cb_t) (void *, blkif_response_t *);
@@ -79,11 +80,19 @@ struct td_vbd_request {
struct list_head next;
};
+struct td_vbd_driver_info {
+ char *params;
+ int type;
+ struct list_head next;
+};
+
struct td_vbd_handle {
char *name;
td_uuid_t uuid;
int type;
+
+ struct list_head driver_stack;
int storage;
@@ -164,6 +173,7 @@ tapdisk_vbd_next_image(td_image_t *image
int tapdisk_vbd_initialize(int, int, td_uuid_t);
void tapdisk_vbd_set_callback(td_vbd_t *, td_vbd_cb_t, void *);
+int tapdisk_vbd_parse_stack(td_vbd_t *vbd, const char *path);
int tapdisk_vbd_open(td_vbd_t *, const char *, uint16_t,
uint16_t, const char *, td_flag_t);
int tapdisk_vbd_close(td_vbd_t *);
diff -r f6091947ffed -r 94c3f3d4b864 tools/blktap2/drivers/tapdisk2.c
--- a/tools/blktap2/drivers/tapdisk2.c Mon Nov 09 19:19:27 2009 +0000
+++ b/tools/blktap2/drivers/tapdisk2.c Mon Nov 09 19:40:14 2009 +0000
@@ -264,6 +264,13 @@ tapdisk2_open_device(int type, const cha
return err;
}
+ err = tapdisk_vbd_parse_stack(vbd, name);
+ if (err) {
+ CHILD_ERR(err, "vbd_parse_stack failed: %d\n", err);
+ return err;
+ }
+
+ /* TODO: clean this up */
err = tapdisk_vbd_open(vbd, path, type,
TAPDISK_STORAGE_TYPE_DEFAULT,
devname, 0);
diff -r f6091947ffed -r 94c3f3d4b864 tools/blktap2/include/list.h
--- a/tools/blktap2/include/list.h Mon Nov 09 19:19:27 2009 +0000
+++ b/tools/blktap2/include/list.h Mon Nov 09 19:40:14 2009 +0000
@@ -87,6 +87,26 @@ static inline int list_is_last(const str
return list->next == head;
}
+static inline void __list_splice(struct list_head *list,
+ struct list_head *head)
+{
+ struct list_head *first = list->next;
+ struct list_head *last = list->prev;
+ struct list_head *at = head->next;
+
+ first->prev = head;
+ head->next = first;
+
+ last->next = at;
+ at->prev = last;
+}
+
+static inline void list_splice(struct list_head *list, struct list_head *head)
+{
+ if (!list_empty(list))
+ __list_splice(list, head);
+}
+
#define list_entry(ptr, type, member) \
((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
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