On 8/28/19 11:07 PM, John Snow wrote:
On 8/7/19 10:21 AM, Daniel Henrique Barboza wrote:
Using the new 'bdrv_co_delete_file' interface, bdrv_delete_file
can be used in a way similar of the existing bdrv_create_file to
to clean up a created file.
The logic is also similar to what is already done in bdrv_create_file:
a qemu_coroutine is created if needed, a specialized function
bdrv_delete_co_entry is used to call the bdrv_co_delete_file
co-routine of the driver, if the driver implements it.
Suggested-by: Daniel P. Berrangé <berra...@redhat.com>
Signed-off-by: Daniel Henrique Barboza <danielhb...@gmail.com>
---
block.c | 77 +++++++++++++++++++++++++++++++++++++++++++
include/block/block.h | 1 +
2 files changed, 78 insertions(+)
diff --git a/block.c b/block.c
index cbd8da5f3b..1e20250627 100644
--- a/block.c
+++ b/block.c
@@ -547,6 +547,83 @@ int bdrv_create_file(const char *filename, QemuOpts *opts,
Error **errp)
return ret;
}
+typedef struct DeleteCo {
+ BlockDriver *drv;
+ BlockDriverState *bs;
+ int ret;
+ Error *err;
+} DeleteCo;
+
+static void coroutine_fn bdrv_delete_co_entry(void *opaque)
+{
+ Error *local_err = NULL;
+ DeleteCo *dco = opaque;
+
+ assert(dco->bs);
+
+ dco->ret = dco->drv->bdrv_co_delete_file(dco->bs, &local_err);
+ error_propagate(&dco->err, local_err);
+}
+
+int bdrv_delete_file(const char *filename, Error **errp)
+{
+ BlockDriver *drv = bdrv_find_protocol(filename, true, NULL);
+ BlockDriverState *bs = bdrv_open(filename, NULL, NULL,
+ BDRV_O_RDWR | BDRV_O_PROTOCOL, NULL);
+ DeleteCo dco = {
+ .drv = drv,
+ .bs = bs,
+ .ret = NOT_DONE,
+ .err = NULL,
+ };
+ Coroutine *co;
+ int ret;
+
+ if (!drv) {
+ error_setg(errp, "File '%s' has unknown format", filename);
+ ret = -ENOENT;
+ goto out;
+ }
+
I was going to say that ENOENT is a weird error here, but I see it used
for !drv a few other places in block.c too, alongside EINVAL and
ENOMEDIUM. ENOMEDIUM loks like the most popular.
Didn't spend too much time thinking about it. I copied the same behavior
from
bdrv_create_file:
---------
int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp)
{
(...)
drv = bdrv_find_protocol(filename, true, errp);
if (drv == NULL) {
return -ENOENT;
}
-----
I can change to ENOMEDIUM if it's indeed more informative than ENOENT.
+ if (!drv->bdrv_co_delete_file) {
+ error_setg(errp, "Driver '%s' does not support image delete",
+ drv->format_name);
+ ret = -ENOTSUP;
+ goto out;
+ }
+
+ if (!bs) {
+ error_setg(errp, "Could not open image '%s' for erasing",
+ filename);
+ ret = 1;
Please keep all errors negative (or at least consistent within a function).
Got it. I'll fix it in the re-spin.
I'm also wondering if we want a version of delete that doesn't try to
open a file directly -- i.e. a version that exists like this:
bdrv_co_delete_file(BlockDriverState *bs, Error **errp);
That simply dispatches based on bs->drv to the correct routine.
Then, you are free to have bdrv_delete_file handle the open (and let the
opening figure out what driver it needs), and just hand off the bds to
bdrv_co_delete_file.
I'm not the authority for block.c, though, so maaaybe I'm giving you bad
advice here. Kevin's away on PTO for a bit and gave you advice most
recently, so I might try to gently ask him for more feedback next week.
I appreciate. I'm not acquainted with the block code at all - I'm playing
by ear since the first version. Any tip is appreciated :)
Thanks,
DHB
+ goto out;
+ }
+
+ if (qemu_in_coroutine()) {
+ /* Fast-path if already in coroutine context */
+ bdrv_delete_co_entry(&dco);
+ } else {
+ co = qemu_coroutine_create(bdrv_delete_co_entry, &dco);
+ qemu_coroutine_enter(co);
+ while (dco.ret == NOT_DONE) {
+ aio_poll(qemu_get_aio_context(), true);
+ }
+ }
+
+ ret = dco.ret;
+ if (ret < 0) {
+ if (dco.err) {
+ error_propagate(errp, dco.err);
+ } else {
+ error_setg_errno(errp, -ret, "Could not delete image");
+ }
+ }
+
+out:
+ bdrv_unref(bs);
+ return ret;
+}
+
/**
* Try to get @bs's logical and physical block size.
* On success, store them in @bsz struct and return 0.
diff --git a/include/block/block.h b/include/block/block.h
index 50a07c1c33..5e83532364 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -369,6 +369,7 @@ bool bdrv_is_backing_chain_frozen(BlockDriverState *bs,
BlockDriverState *base,
int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base,
Error **errp);
void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState
*base);
+int bdrv_delete_file(const char *filename, Error **errp);
typedef struct BdrvCheckResult {
