From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40229) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cgsdu-0005R0-AZ for qemu-devel@nongnu.org; Thu, 23 Feb 2017 07:37:07 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cgsdt-0007zy-HF for qemu-devel@nongnu.org; Thu, 23 Feb 2017 07:37:06 -0500 Date: Thu, 23 Feb 2017 20:36:57 +0800 From: Fam Zheng Message-ID: <20170223123657.GG14175@lemon.lan> References: <1487689130-30373-1-git-send-email-kwolf@redhat.com> <1487689130-30373-17-git-send-email-kwolf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1487689130-30373-17-git-send-email-kwolf@redhat.com> Subject: Re: [Qemu-devel] [PATCH 16/54] block: Default .bdrv_child_perm() for filter drivers List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: qemu-block@nongnu.org, mreitz@redhat.com, jcody@redhat.com, qemu-devel@nongnu.org On Tue, 02/21 15:58, Kevin Wolf wrote: > Most filters need permissions related to read and write for their > children, but only if the node has a parent that wants to use the same > operation on the filter. The same is true for resize. I cannot parse this paragraph, especially the 'but only if' part.. > > This adds a default implementation that simply forwards all necessary > permissions to all children of the node and leaves the other permissions > unchanged. > > Signed-off-by: Kevin Wolf > --- > block.c | 24 ++++++++++++++++++++++++ > include/block/block_int.h | 8 ++++++++ > 2 files changed, 32 insertions(+) > > diff --git a/block.c b/block.c > index 2a86781..523cbd3 100644 > --- a/block.c > +++ b/block.c > @@ -1531,6 +1531,30 @@ int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared, > return 0; > } > > +#define DEFAULT_PERM_PASSTHROUGH (BLK_PERM_CONSISTENT_READ \ > + | BLK_PERM_WRITE \ > + | BLK_PERM_WRITE_UNCHANGED \ > + | BLK_PERM_RESIZE) > +#define DEFAULT_PERM_UNCHANGED (BLK_PERM_ALL & ~DEFAULT_PERM_PASSTHROUGH) > + > +void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c, > + const BdrvChildRole *role, > + uint64_t perm, uint64_t shared, > + uint64_t *nperm, uint64_t *nshared) > +{ > + if (c == NULL) { > + *nperm = 0; > + *nshared = BLK_PERM_ALL; > + return; > + } > + > + *nperm = (perm & DEFAULT_PERM_PASSTHROUGH) | > + (c->perm & DEFAULT_PERM_UNCHANGED); > + *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | > + (c->shared_perm & DEFAULT_PERM_UNCHANGED); > +} > + > + > static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs) > { > BlockDriverState *old_bs = child->bs; > diff --git a/include/block/block_int.h b/include/block/block_int.h > index cef2b6e..17f4c2d 100644 > --- a/include/block/block_int.h > +++ b/include/block/block_int.h > @@ -872,6 +872,14 @@ void bdrv_child_abort_perm_update(BdrvChild *c); > int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared, > Error **errp); > > +/* Default implementation for BlockDriver.bdrv_child_perm() that can be used by > + * block filters: Forward CONSISTENT_READ, WRITE, WRITE_UNCHANGED and RESIZE to > + * all children */ > +void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c, > + const BdrvChildRole *role, > + uint64_t perm, uint64_t shared, > + uint64_t *nperm, uint64_t *nshared); > + > > const char *bdrv_get_parent_name(const BlockDriverState *bs); > void blk_dev_change_media_cb(BlockBackend *blk, bool load); > -- > 1.8.3.1 >