| Message ID | 1371124063-12971-6-git-send-email-kwolf@redhat.com |
|---|---|
| State | New |
| Headers | show |
Il 13/06/2013 07:47, Kevin Wolf ha scritto: > Turning on discard options in qcow2 doesn't help a lot when the discard > requests that it issues are thrown away by the raw-posix layer. This > patch always enables discard functionality on the protocol level so that > it's the image format's responsibility to send (or not) discard > requests. Requests sent by the guest will be allowed or ignored by the > top level BlockDriverState, which depends on the discard=... option like > before. > > In particular, this means that even without specifying options, the > qcow2 default of discarding deleted snapshots actually takes effect now, > both for qemu and qemu-img. > > Signed-off-by: Kevin Wolf <kwolf@redhat.com> > --- > block.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/block.c b/block.c > index 79ad33d..0a7cf2f 100644 > --- a/block.c > +++ b/block.c > @@ -1045,7 +1045,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options, > extract_subqdict(options, &file_options, "file."); > > ret = bdrv_file_open(&file, filename, file_options, > - bdrv_open_flags(bs, flags)); > + bdrv_open_flags(bs, flags | BDRV_O_UNMAP)); > if (ret < 0) { > goto fail; > } > Can you still disable it with -drive file.discard=ignore? Paolo
Am 14.06.2013 um 00:06 hat Paolo Bonzini geschrieben: > Il 13/06/2013 07:47, Kevin Wolf ha scritto: > > Turning on discard options in qcow2 doesn't help a lot when the discard > > requests that it issues are thrown away by the raw-posix layer. This > > patch always enables discard functionality on the protocol level so that > > it's the image format's responsibility to send (or not) discard > > requests. Requests sent by the guest will be allowed or ignored by the > > top level BlockDriverState, which depends on the discard=... option like > > before. > > > > In particular, this means that even without specifying options, the > > qcow2 default of discarding deleted snapshots actually takes effect now, > > both for qemu and qemu-img. > > > > Signed-off-by: Kevin Wolf <kwolf@redhat.com> > > --- > > block.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/block.c b/block.c > > index 79ad33d..0a7cf2f 100644 > > --- a/block.c > > +++ b/block.c > > @@ -1045,7 +1045,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options, > > extract_subqdict(options, &file_options, "file."); > > > > ret = bdrv_file_open(&file, filename, file_options, > > - bdrv_open_flags(bs, flags)); > > + bdrv_open_flags(bs, flags | BDRV_O_UNMAP)); > > if (ret < 0) { > > goto fail; > > } > > > > Can you still disable it with -drive file.discard=ignore? This requires a few more changes (basically moving BDRV_O_UNMAP from flags into a boolean in the QDict), but I think eventually we'll want to allow this. Kevin
diff --git a/block.c b/block.c index 79ad33d..0a7cf2f 100644 --- a/block.c +++ b/block.c @@ -1045,7 +1045,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options, extract_subqdict(options, &file_options, "file."); ret = bdrv_file_open(&file, filename, file_options, - bdrv_open_flags(bs, flags)); + bdrv_open_flags(bs, flags | BDRV_O_UNMAP)); if (ret < 0) { goto fail; }
Turning on discard options in qcow2 doesn't help a lot when the discard requests that it issues are thrown away by the raw-posix layer. This patch always enables discard functionality on the protocol level so that it's the image format's responsibility to send (or not) discard requests. Requests sent by the guest will be allowed or ignored by the top level BlockDriverState, which depends on the discard=... option like before. In particular, this means that even without specifying options, the qcow2 default of discarding deleted snapshots actually takes effect now, both for qemu and qemu-img. Signed-off-by: Kevin Wolf <kwolf@redhat.com> --- block.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)