[Xen-changelog] [xen-unstable] [TAPDISK] minor changes to tapdisk and plugins

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[Xen-changelog] [xen-unstable] [TAPDISK] minor changes to tapdisk and plugins

Xen patchbot-unstable
# HG changeset patch
# User Jake Wires <[hidden email]>
# Date 1172208737 28800
# Node ID 8407279d3751ff27e7f1826298c9adb2c46d71de
# Parent  da37c365b375fbf6335c5d7cdf5429f2bf1259d0
[TAPDISK] minor changes to tapdisk and plugins
* open all parent images read-only
* expose parent image names to tapdisk (needed for locking api)
Signed-off-by: Jake Wires <[hidden email]>
---
 tools/blktap/drivers/block-aio.c  |   33 ++++----
 tools/blktap/drivers/block-qcow.c |   85 +++++++++++---------
 tools/blktap/drivers/block-ram.c  |   28 +++---
 tools/blktap/drivers/block-sync.c |   28 +++---
 tools/blktap/drivers/block-vmdk.c |   29 ++++---
 tools/blktap/drivers/img2qcow.c   |    2
 tools/blktap/drivers/qcow2raw.c   |    4
 tools/blktap/drivers/tapdisk.c    |  154 +++++++++++++++++++++++---------------
 tools/blktap/drivers/tapdisk.h    |   44 +++++++---
 9 files changed, 244 insertions(+), 163 deletions(-)

diff -r da37c365b375 -r 8407279d3751 tools/blktap/drivers/block-aio.c
--- a/tools/blktap/drivers/block-aio.c Thu Feb 22 22:27:40 2007 +0000
+++ b/tools/blktap/drivers/block-aio.c Thu Feb 22 21:32:17 2007 -0800
@@ -152,9 +152,9 @@ static inline void init_fds(struct disk_
 }
 
 /* Open the disk file and initialize aio state. */
-int tdaio_open (struct disk_driver *dd, const char *name)
-{
- int i, fd, ret = 0;
+int tdaio_open (struct disk_driver *dd, const char *name, td_flag_t flags)
+{
+ int i, fd, ret = 0, o_flags;
  struct td_state    *s   = dd->td_state;
  struct tdaio_state *prv = (struct tdaio_state *)dd->private;
 
@@ -187,12 +187,15 @@ int tdaio_open (struct disk_driver *dd,
  prv->iocb_free[i] = &prv->iocb_list[i];
 
  /* Open the file */
-        fd = open(name, O_RDWR | O_DIRECT | O_LARGEFILE);
+ o_flags = O_DIRECT | O_LARGEFILE |
+ ((flags == TD_RDONLY) ? O_RDONLY : O_RDWR);
+        fd = open(name, o_flags);
 
         if ( (fd == -1) && (errno == EINVAL) ) {
 
                 /* Maybe O_DIRECT isn't supported. */
-                fd = open(name, O_RDWR | O_LARGEFILE);
+ o_flags &= ~O_DIRECT;
+                fd = open(name, o_flags);
                 if (fd != -1) DPRINTF("WARNING: Accessing image without"
                                      "O_DIRECT! (%s)\n", name);
 
@@ -279,6 +282,9 @@ int tdaio_submit(struct disk_driver *dd)
 {
  int ret;
  struct tdaio_state *prv = (struct tdaio_state *)dd->private;
+
+ if (!prv->iocb_queued)
+ return 0;
 
  ret = io_submit(prv->aio_ctx, prv->iocb_queued, prv->iocb_queue);
 
@@ -324,12 +330,13 @@ int tdaio_do_callbacks(struct disk_drive
  return rsp;
 }
 
-int tdaio_has_parent(struct disk_driver *dd)
-{
- return 0;
-}
-
-int tdaio_get_parent(struct disk_driver *dd, struct disk_driver *parent)
+int tdaio_get_parent_id(struct disk_driver *dd, struct disk_id *id)
+{
+ return TD_NO_PARENT;
+}
+
+int tdaio_validate_parent(struct disk_driver *dd,
+  struct disk_driver *parent, td_flag_t flags)
 {
  return -EINVAL;
 }
@@ -341,8 +348,8 @@ struct tap_disk tapdisk_aio = {
  .td_queue_read      = tdaio_queue_read,
  .td_queue_write     = tdaio_queue_write,
  .td_submit          = tdaio_submit,
- .td_has_parent      = tdaio_has_parent,
- .td_get_parent      = tdaio_get_parent,
  .td_close           = tdaio_close,
  .td_do_callbacks    = tdaio_do_callbacks,
+ .td_get_parent_id   = tdaio_get_parent_id,
+ .td_validate_parent = tdaio_validate_parent
 };
diff -r da37c365b375 -r 8407279d3751 tools/blktap/drivers/block-qcow.c
--- a/tools/blktap/drivers/block-qcow.c Thu Feb 22 22:27:40 2007 +0000
+++ b/tools/blktap/drivers/block-qcow.c Thu Feb 22 21:32:17 2007 -0800
@@ -207,23 +207,6 @@ static int init_aio_state(struct disk_dr
 
  fail:
  return -1;
-}
-
-/*
- *Test if block is zero.
- * Return:
- *       1 for TRUE
- *       0 for FALSE
- */
-static inline int IS_ZERO(char *buf, int len)
-{
- int i;
-
- for (i = 0; i < len; i++) {
- /*if not zero, return false*/
- if (ZERO_TEST(*(buf + i))) return 0;
- }
- return 1;
 }
 
 static uint32_t gen_cksum(char *ptr, int len)
@@ -825,9 +808,9 @@ static inline void init_fds(struct disk_
 }
 
 /* Open the disk file and initialize qcow state. */
-int tdqcow_open (struct disk_driver *dd, const char *name)
-{
- int fd, len, i, shift, ret, size, l1_table_size;
+int tdqcow_open (struct disk_driver *dd, const char *name, td_flag_t flags)
+{
+ int fd, len, i, shift, ret, size, l1_table_size, o_flags;
  struct td_state     *bs = dd->td_state;
  struct tdqcow_state *s  = (struct tdqcow_state *)dd->private;
  char *buf;
@@ -838,7 +821,9 @@ int tdqcow_open (struct disk_driver *dd,
 
  DPRINTF("QCOW: Opening %s\n",name);
 
- fd = open(name, O_RDWR | O_DIRECT | O_LARGEFILE);
+ o_flags = O_DIRECT | O_LARGEFILE |
+ ((flags == TD_RDONLY) ? O_RDONLY : O_RDWR);
+ fd = open(name, o_flags);
  if (fd < 0) {
  DPRINTF("Unable to open %s (%d)\n",name,0 - errno);
  return -1;
@@ -1016,7 +1001,8 @@ int tdqcow_queue_read(struct disk_driver
  * as busy and try again later */
  return cb(dd, -EBUSY, sector + n,
   nb_sectors - n, id, private);
- } else rsp += ret;
+ } else
+ rsp += ret;
  } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
  aio_unlock(s, sector);
  if (decompress_cluster(s, cluster_offset) < 0) {
@@ -1403,21 +1389,15 @@ int qcow_compress_cluster(struct tdqcow_
  return 0;
 }
 
-int tdqcow_has_parent(struct disk_driver *dd)
-{
- struct tdqcow_state *s = (struct tdqcow_state *)dd->private;
- return (s->backing_file_offset ? 1 : 0);
-}
-
-int tdqcow_get_parent(struct disk_driver *cdd, struct disk_driver *pdd)
+int tdqcow_get_parent_id(struct disk_driver *dd, struct disk_id *id)
 {
  off_t off;
  char *buf, *filename;
- int len, secs, ret = -1;
- struct tdqcow_state *child  = (struct tdqcow_state *)cdd->private;
+ int len, secs, err = -EINVAL;
+ struct tdqcow_state *child  = (struct tdqcow_state *)dd->private;
 
  if (!child->backing_file_offset)
- return -1;
+ return TD_NO_PARENT;
 
  /* read the backing file name */
  len  = child->backing_file_size;
@@ -1432,14 +1412,39 @@ int tdqcow_get_parent(struct disk_driver
 
  if (read(child->fd, buf, secs << 9) != secs << 9)
  goto out;
- filename      = buf + (child->backing_file_offset - off);
- filename[len] = '\0';
-
- /*Open backing file*/
- ret = tdqcow_open(pdd, filename);
+ filename       = buf + (child->backing_file_offset - off);
+ filename[len]  = '\0';
+
+ id->name       = strdup(filename);
+ id->drivertype = DISK_TYPE_QCOW;
+ err            = 0;
  out:
  free(buf);
- return ret;
+ return err;
+}
+
+int tdqcow_validate_parent(struct disk_driver *child,
+   struct disk_driver *parent, td_flag_t flags)
+{
+ struct stat stats;
+ uint64_t psize, csize;
+ struct tdqcow_state *c = (struct tdqcow_state *)child->private;
+ struct tdqcow_state *p = (struct tdqcow_state *)parent->private;
+
+ if (stat(p->name, &stats))
+ return -EINVAL;
+ if (get_filesize(p->name, &psize, &stats))
+ return -EINVAL;
+
+ if (stat(c->name, &stats))
+ return -EINVAL;
+ if (get_filesize(c->name, &csize, &stats))
+ return -EINVAL;
+
+ if (csize != psize)
+ return -EINVAL;
+
+ return 0;
 }
 
 struct tap_disk tapdisk_qcow = {
@@ -1449,8 +1454,8 @@ struct tap_disk tapdisk_qcow = {
  .td_queue_read       = tdqcow_queue_read,
  .td_queue_write      = tdqcow_queue_write,
  .td_submit           = tdqcow_submit,
- .td_has_parent       = tdqcow_has_parent,
- .td_get_parent       = tdqcow_get_parent,
  .td_close            = tdqcow_close,
  .td_do_callbacks     = tdqcow_do_callbacks,
+ .td_get_parent_id    = tdqcow_get_parent_id,
+ .td_validate_parent  = tdqcow_validate_parent
 };
diff -r da37c365b375 -r 8407279d3751 tools/blktap/drivers/block-ram.c
--- a/tools/blktap/drivers/block-ram.c Thu Feb 22 22:27:40 2007 +0000
+++ b/tools/blktap/drivers/block-ram.c Thu Feb 22 21:32:17 2007 -0800
@@ -135,11 +135,11 @@ static inline void init_fds(struct disk_
 }
 
 /* Open the disk file and initialize ram state. */
-int tdram_open (struct disk_driver *dd, const char *name)
+int tdram_open (struct disk_driver *dd, const char *name, td_flag_t flags)
 {
  char *p;
  uint64_t size;
- int i, fd, ret = 0, count = 0;
+ int i, fd, ret = 0, count = 0, o_flags;
  struct td_state    *s     = dd->td_state;
  struct tdram_state *prv   = (struct tdram_state *)dd->private;
 
@@ -167,12 +167,15 @@ int tdram_open (struct disk_driver *dd,
  }
 
  /* Open the file */
-        fd = open(name, O_RDWR | O_DIRECT | O_LARGEFILE);
+ o_flags = O_DIRECT | O_LARGEFILE |
+ ((flags == TD_RDONLY) ? O_RDONLY : O_RDWR);
+        fd = open(name, o_flags);
 
         if ((fd == -1) && (errno == EINVAL)) {
 
                 /* Maybe O_DIRECT isn't supported. */
-                fd = open(name, O_RDWR | O_LARGEFILE);
+ o_flags &= ~O_DIRECT;
+                fd = open(name, o_flags);
                 if (fd != -1) DPRINTF("WARNING: Accessing image without"
                                      "O_DIRECT! (%s)\n", name);
 
@@ -275,12 +278,13 @@ int tdram_do_callbacks(struct disk_drive
  return 1;
 }
 
-int tdram_has_parent(struct disk_driver *dd)
-{
- return 0;
-}
-
-int tdram_get_parent(struct disk_driver *dd, struct disk_driver *parent)
+int tdram_get_parent_id(struct disk_driver *dd, struct disk_id *id)
+{
+ return TD_NO_PARENT;
+}
+
+int tdram_validate_parent(struct disk_driver *dd,
+  struct disk_driver *parent, td_flag_t flags)
 {
  return -EINVAL;
 }
@@ -292,8 +296,8 @@ struct tap_disk tapdisk_ram = {
  .td_queue_read      = tdram_queue_read,
  .td_queue_write     = tdram_queue_write,
  .td_submit          = tdram_submit,
- .td_has_parent      = tdram_has_parent,
- .td_get_parent      = tdram_get_parent,
  .td_close           = tdram_close,
  .td_do_callbacks    = tdram_do_callbacks,
+ .td_get_parent_id   = tdram_get_parent_id,
+ .td_validate_parent = tdram_validate_parent
 };
diff -r da37c365b375 -r 8407279d3751 tools/blktap/drivers/block-sync.c
--- a/tools/blktap/drivers/block-sync.c Thu Feb 22 22:27:40 2007 +0000
+++ b/tools/blktap/drivers/block-sync.c Thu Feb 22 21:32:17 2007 -0800
@@ -118,9 +118,9 @@ static inline void init_fds(struct disk_
 }
 
 /* Open the disk file and initialize aio state. */
-int tdsync_open (struct disk_driver *dd, const char *name)
-{
- int i, fd, ret = 0;
+int tdsync_open (struct disk_driver *dd, const char *name, td_flag_t flags)
+{
+ int i, fd, ret = 0, o_flags;
  struct td_state     *s   = dd->td_state;
  struct tdsync_state *prv = (struct tdsync_state *)dd->private;
 
@@ -130,11 +130,14 @@ int tdsync_open (struct disk_driver *dd,
  return (0 - errno);
 
  /* Open the file */
-        fd = open(name, O_RDWR | O_DIRECT | O_LARGEFILE);
+ o_flags = O_DIRECT | O_LARGEFILE |
+ ((flags == TD_RDONLY) ? O_RDONLY : O_RDWR);
+        fd = open(name, o_flags);
 
         if ( (fd == -1) && (errno == EINVAL) ) {
 
                 /* Maybe O_DIRECT isn't supported. */
+ o_flags &= ~O_DIRECT;
                 fd = open(name, O_RDWR | O_LARGEFILE);
                 if (fd != -1) DPRINTF("WARNING: Accessing image without"
                                      "O_DIRECT! (%s)\n", name);
@@ -223,12 +226,13 @@ int tdsync_do_callbacks(struct disk_driv
  return 1;
 }
 
-int tdsync_has_parent(struct disk_driver *dd)
-{
- return 0;
-}
-
-int tdsync_get_parent(struct disk_driver *dd, struct disk_driver *parent)
+int tdsync_get_parent_id(struct disk_driver *dd, struct disk_id *id)
+{
+ return TD_NO_PARENT;
+}
+
+int tdsync_validate_parent(struct disk_driver *dd,
+   struct disk_driver *parent, td_flag_t flags)
 {
  return -EINVAL;
 }
@@ -240,8 +244,8 @@ struct tap_disk tapdisk_sync = {
  .td_queue_read       = tdsync_queue_read,
  .td_queue_write      = tdsync_queue_write,
  .td_submit           = tdsync_submit,
- .td_has_parent       = tdsync_has_parent,
- .td_get_parent       = tdsync_get_parent,
  .td_close            = tdsync_close,
  .td_do_callbacks     = tdsync_do_callbacks,
+ .td_get_parent_id    = tdsync_get_parent_id,
+ .td_validate_parent  = tdsync_validate_parent
 };
diff -r da37c365b375 -r 8407279d3751 tools/blktap/drivers/block-vmdk.c
--- a/tools/blktap/drivers/block-vmdk.c Thu Feb 22 22:27:40 2007 +0000
+++ b/tools/blktap/drivers/block-vmdk.c Thu Feb 22 21:32:17 2007 -0800
@@ -119,10 +119,11 @@ static inline void init_fds(struct disk_
 }
 
 /* Open the disk file and initialize aio state. */
-static int tdvmdk_open (struct disk_driver *dd, const char *name)
+static int tdvmdk_open (struct disk_driver *dd,
+ const char *name, td_flag_t flags)
 {
  int ret, fd;
-     int l1_size, i;
+     int l1_size, i, o_flags;
      uint32_t magic;
  struct td_state     *s   = dd->td_state;
  struct tdvmdk_state *prv = (struct tdvmdk_state *)dd->private;
@@ -133,12 +134,15 @@ static int tdvmdk_open (struct disk_driv
  return -1;
 
  /* Open the file */
-        fd = open(name, O_RDWR | O_LARGEFILE);
+ o_flags = O_DIRECT | O_LARGEFILE |
+ ((flags == TD_RDONLY) ? O_RDONLY : O_RDWR);
+        fd = open(name, o_flags);
 
         if ( (fd == -1) && (errno == EINVAL) ) {
 
                 /* Maybe O_DIRECT isn't supported. */
-                fd = open(name, O_RDWR | O_LARGEFILE);
+ o_flags &= ~O_DIRECT;
+                fd = open(name, o_flags);
                 if (fd != -1) DPRINTF("WARNING: Accessing image without"
                                      "O_DIRECT! (%s)\n", name);
 
@@ -394,12 +398,13 @@ static int tdvmdk_do_callbacks(struct di
  return 1;
 }
 
-static int tdvmdk_has_parent(struct disk_driver *dd)
-{
- return 0;
-}
-
-static int tdvmdk_get_parent(struct disk_driver *dd, struct disk_driver *parent)
+static int tdvmdk_get_parent_id(struct disk_driver *dd, struct disk_id *id)
+{
+ return TD_NO_PARENT;
+}
+
+static int tdvmdk_validate_parent(struct disk_driver *dd,
+  struct disk_driver *parent, td_flag_t flags)
 {
  return -EINVAL;
 }
@@ -411,8 +416,8 @@ struct tap_disk tapdisk_vmdk = {
  .td_queue_read       = tdvmdk_queue_read,
  .td_queue_write      = tdvmdk_queue_write,
  .td_submit           = tdvmdk_submit,
- .td_has_parent       = tdvmdk_has_parent,
- .td_get_parent       = tdvmdk_get_parent,
  .td_close            = tdvmdk_close,
  .td_do_callbacks     = tdvmdk_do_callbacks,
+ .td_get_parent_id    = tdvmdk_get_parent_id,
+ .td_validate_parent  = tdvmdk_validate_parent
 };
diff -r da37c365b375 -r 8407279d3751 tools/blktap/drivers/img2qcow.c
--- a/tools/blktap/drivers/img2qcow.c Thu Feb 22 22:27:40 2007 +0000
+++ b/tools/blktap/drivers/img2qcow.c Thu Feb 22 21:32:17 2007 -0800
@@ -201,7 +201,7 @@ int main(int argc, char *argv[])
  dd.private  = malloc(dd.drv->private_data_size);
 
         /*Open qcow file*/
-        if (dd.drv->td_open(&dd, argv[1])!=0) {
+        if (dd.drv->td_open(&dd, argv[1], 0)!=0) {
  DFPRINTF("Unable to open Qcow file [%s]\n",argv[1]);
  exit(-1);
  }
diff -r da37c365b375 -r 8407279d3751 tools/blktap/drivers/qcow2raw.c
--- a/tools/blktap/drivers/qcow2raw.c Thu Feb 22 22:27:40 2007 +0000
+++ b/tools/blktap/drivers/qcow2raw.c Thu Feb 22 21:32:17 2007 -0800
@@ -169,7 +169,7 @@ int main(int argc, char *argv[])
  ddqcow.drv = &tapdisk_qcow;
  ddqcow.private = malloc(ddqcow.drv->private_data_size);
 
-        if (ddqcow.drv->td_open(&ddqcow, argv[2])!=0) {
+        if (ddqcow.drv->td_open(&ddqcow, argv[2], TD_RDONLY)!=0) {
  DFPRINTF("Unable to open Qcow file [%s]\n",argv[2]);
  exit(-1);
  } else DFPRINTF("QCOW file opened, size %llu\n",
@@ -270,7 +270,7 @@ int main(int argc, char *argv[])
  ddaio.drv = &tapdisk_aio;
  ddaio.private = malloc(ddaio.drv->private_data_size);
 
-        if (ddaio.drv->td_open(&ddaio, argv[1])!=0) {
+        if (ddaio.drv->td_open(&ddaio, argv[1], 0)!=0) {
  DFPRINTF("Unable to open Qcow file [%s]\n", argv[1]);
  exit(-1);
  }
diff -r da37c365b375 -r 8407279d3751 tools/blktap/drivers/tapdisk.c
--- a/tools/blktap/drivers/tapdisk.c Thu Feb 22 22:27:40 2007 +0000
+++ b/tools/blktap/drivers/tapdisk.c Thu Feb 22 21:32:17 2007 -0800
@@ -81,6 +81,15 @@ void daemonize(void)
  return;
 }
 
+static void free_driver(struct disk_driver *d)
+{
+ if (d->name)
+ free(d->name);
+ if (d->private)
+ free(d->private);
+ free(d);
+}
+
 static void unmap_disk(struct td_state *s)
 {
  tapdev_info_t *info = s->ring_info;
@@ -91,8 +100,7 @@ static void unmap_disk(struct td_state *
  while (dd) {
  tmp = dd->next;
  dd->drv->td_close(dd);
- free(dd->private);
- free(dd);
+ free_driver(dd);
  dd = tmp;
  }
 
@@ -112,7 +120,6 @@ static void unmap_disk(struct td_state *
  free(s);
 
  return;
-
 }
 
 void sig_handler(int sig)
@@ -205,26 +212,6 @@ static struct td_state *state_init(void)
  return s;
 }
 
-static struct disk_driver *disk_init(struct td_state *s, struct tap_disk *drv)
-{
- struct disk_driver *dd;
-
- dd = calloc(1, sizeof(struct disk_driver));
- if (!dd)
- return NULL;
-
- dd->private = malloc(drv->private_data_size);
- if (!dd->private) {
- free(dd);
- return NULL;
- }
-
- dd->drv      = drv;
- dd->td_state = s;
-
- return dd;
-}
-
 static int map_new_dev(struct td_state *s, int minor)
 {
  int tap_fd;
@@ -280,49 +267,94 @@ static int map_new_dev(struct td_state *
  return -1;
 }
 
-static int open_disk(struct td_state *s, struct disk_driver *dd, char *path)
+static struct disk_driver *disk_init(struct td_state *s,
+     struct tap_disk *drv, char *name)
+{
+ struct disk_driver *dd;
+
+ dd = calloc(1, sizeof(struct disk_driver));
+ if (!dd)
+ return NULL;
+
+ dd->private = malloc(drv->private_data_size);
+ if (!dd->private) {
+ free(dd);
+ return NULL;
+ }
+
+ dd->drv      = drv;
+ dd->td_state = s;
+ dd->name     = name;
+
+ return dd;
+}
+
+static int open_disk(struct td_state *s, struct tap_disk *drv, char *path)
 {
  int err;
- struct disk_driver *d = dd;
-
- err = dd->drv->td_open(dd, path);
+ char *dup;
+ struct disk_id id;
+ struct disk_driver *d;
+
+ dup = strdup(path);
+ if (!dup)
+ return -ENOMEM;
+
+ memset(&id, 0, sizeof(struct disk_id));
+ s->disks = d = disk_init(s, drv, dup);
+ if (!d)
+ return -ENOMEM;
+
+ err = drv->td_open(d, path, 0);
  if (err)
- return err;
+ goto fail;
 
  /* load backing files as necessary */
- while (d->drv->td_has_parent(d)) {
+ while ((err = d->drv->td_get_parent_id(d, &id)) == 0) {
  struct disk_driver *new;
 
- new = calloc(1, sizeof(struct disk_driver));
+ if (id.drivertype > MAX_DISK_TYPES ||
+    !get_driver(id.drivertype) || !id.name)
+ goto fail;
+
+ dup = strdup(id.name);
+ if (!dup)
+ goto fail;
+
+ new = disk_init(s, get_driver(id.drivertype), dup);
  if (!new)
  goto fail;
- new->drv      = d->drv;
- new->td_state = s;
- new->private  = malloc(new->drv->private_data_size);
- if (!new->private) {
- free(new);
+
+ err = new->drv->td_open(new, new->name, TD_RDONLY);
+ if (err)
+ goto fail;
+
+ err = d->drv->td_validate_parent(d, new, 0);
+ if (err) {
+ d->next = new;
  goto fail;
  }
-
- err = d->drv->td_get_parent(d, new);
- if (err)
- goto fail;
 
  d = d->next = new;
- }
-
- return 0;
+ free(id.name);
+ }
+
+ if (err >= 0)
+ return 0;
 
  fail:
  DPRINTF("failed opening disk\n");
- while (dd) {
- d = dd->next;
- dd->drv->td_close(dd);
- free(dd->private);
- free(dd);
- dd = d;
- }
- return err;
+ if (id.name)
+ free(id.name);
+ d = s->disks;
+ while (d) {
+ struct disk_driver *tmp = d->next;
+ d->drv->td_close(d);
+ free_driver(d);
+ d = tmp;
+ }
+ s->disks = NULL;
+ return -1;
 }
 
 static int read_msg(char *buf)
@@ -334,7 +366,6 @@ static int read_msg(char *buf)
  msg_newdev_t *msg_dev;
  msg_pid_t *msg_pid;
  struct tap_disk *drv;
- struct disk_driver *dd;
  int ret = -1;
  struct td_state *s = NULL;
  fd_list_entry_t *entry;
@@ -369,14 +400,8 @@ static int read_msg(char *buf)
  if (s == NULL)
  goto params_done;
 
- s->disks = dd = disk_init(s, drv);
- if (!dd) {
- free(s);
- goto params_done;
- }
-
  /*Open file*/
- ret = open_disk(s, dd, path);
+ ret = open_disk(s, drv, path);
  if (ret)
  goto params_done;
 
@@ -785,6 +810,19 @@ int main(int argc, char *argv[])
  }
  }
 
+ /* completed io from above may have
+ * queued new requests on chained disks */
+ if (progress_made) {
+ td_for_each_disk(ptr->s, dd) {
+ dd->early +=
+ dd->drv->td_submit(dd);
+ if (dd->early > 0) {
+ io_done(dd, 10);
+ dd->early = 0;
+ }
+ }
+ }
+
  if (FD_ISSET(ptr->tap_fd, &readfds) ||
     (info->busy.req && progress_made))
  get_io_request(ptr->s);
diff -r da37c365b375 -r 8407279d3751 tools/blktap/drivers/tapdisk.h
--- a/tools/blktap/drivers/tapdisk.h Thu Feb 22 22:27:40 2007 +0000
+++ b/tools/blktap/drivers/tapdisk.h Thu Feb 22 21:32:17 2007 -0800
@@ -42,10 +42,15 @@
  *
  *   - The fd used for poll is an otherwise unused pipe, which allows poll to
  *     be safely called without ever returning anything.
- *
+ *
  * NOTE: tapdisk uses the number of sectors submitted per request as a
  * ref count.  Plugins must use the callback function to communicate the
  * completion--or error--of every sector submitted to them.
+ *
+ * td_get_parent_id returns:
+ *     0 if parent id successfully retrieved
+ *     TD_NO_PARENT if no parent exists
+ *     -errno on error
  */
 
 #ifndef TAPDISK_H_
@@ -71,12 +76,23 @@
 #define MAX_IOFD                 2
 
 #define BLK_NOT_ALLOCATED       99
+#define TD_NO_PARENT             1
+
+typedef uint32_t td_flag_t;
+
+#define TD_RDONLY                1
 
 struct td_state;
 struct tap_disk;
 
+struct disk_id {
+ char *name;
+ int drivertype;
+};
+
 struct disk_driver {
  int early;
+ char *name;
  void *private;
  int io_fd[MAX_IOFD];
  struct tap_disk *drv;
@@ -105,18 +121,20 @@ struct tap_disk {
 struct tap_disk {
  const char *disk_type;
  int private_data_size;
- int (*td_open)        (struct disk_driver *dd, const char *name);
- int (*td_queue_read)  (struct disk_driver *dd, uint64_t sector,
-       int nb_sectors, char *buf, td_callback_t cb,
-       int id, void *prv);
- int (*td_queue_write) (struct disk_driver *dd, uint64_t sector,
-       int nb_sectors, char *buf, td_callback_t cb,
-       int id, void *prv);
- int (*td_submit)      (struct disk_driver *dd);
- int (*td_has_parent)  (struct disk_driver *dd);
- int (*td_get_parent)  (struct disk_driver *dd, struct disk_driver *p);
- int (*td_close)       (struct disk_driver *dd);
- int (*td_do_callbacks)(struct disk_driver *dd, int sid);
+ int (*td_open)           (struct disk_driver *dd,
+  const char *name, td_flag_t flags);
+ int (*td_queue_read)     (struct disk_driver *dd, uint64_t sector,
+  int nb_sectors, char *buf, td_callback_t cb,
+  int id, void *prv);
+ int (*td_queue_write)    (struct disk_driver *dd, uint64_t sector,
+  int nb_sectors, char *buf, td_callback_t cb,
+  int id, void *prv);
+ int (*td_submit)         (struct disk_driver *dd);
+ int (*td_close)          (struct disk_driver *dd);
+ int (*td_do_callbacks)   (struct disk_driver *dd, int sid);
+ int (*td_get_parent_id)  (struct disk_driver *dd, struct disk_id *id);
+ int (*td_validate_parent)(struct disk_driver *dd,
+  struct disk_driver *p, td_flag_t flags);
 };
 
 typedef struct disk_info {

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