| Message ID | 20170116204921.31578-3-mreitz@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 01/16/2017 02:49 PM, Max Reitz wrote: > This function may be implemented by block drivers to derive a directory > name from a BDS. Concatenating this g_free()-able string with a relative > filename must result in a valid (not necessarily existing) filename, so > this is a function that should generally be not implemented by format > drivers, because this is protocol-specific. > > If a BDS's driver does not implement this function, bdrv_dirname() will > fall through to the BDS's file if it exists. If it does not, the > exact_filename field will be used to generate a directory name. > > Signed-off-by: Max Reitz <mreitz@redhat.com> > --- > include/block/block.h | 1 + > include/block/block_int.h | 1 + > block.c | 26 ++++++++++++++++++++++++++ > 3 files changed, 28 insertions(+) > +++ b/include/block/block_int.h > @@ -130,6 +130,7 @@ struct BlockDriver { > int (*bdrv_make_empty)(BlockDriverState *bs); > > void (*bdrv_refresh_filename)(BlockDriverState *bs, QDict *options); > + char *(*bdrv_dirname)(BlockDriverState *bs, Error **errp); I know we've been lousy at documentation in the past, but should we start doing a better job of documenting the contract as we add new callbacks, rather than just the commit messages? Based on existing practice, though, I'm okay with: Reviewed-by: Eric Blake <eblake@redhat.com>
On 17.01.2017 00:02, Eric Blake wrote: > On 01/16/2017 02:49 PM, Max Reitz wrote: >> This function may be implemented by block drivers to derive a directory >> name from a BDS. Concatenating this g_free()-able string with a relative >> filename must result in a valid (not necessarily existing) filename, so >> this is a function that should generally be not implemented by format >> drivers, because this is protocol-specific. >> >> If a BDS's driver does not implement this function, bdrv_dirname() will >> fall through to the BDS's file if it exists. If it does not, the >> exact_filename field will be used to generate a directory name. >> >> Signed-off-by: Max Reitz <mreitz@redhat.com> >> --- >> include/block/block.h | 1 + >> include/block/block_int.h | 1 + >> block.c | 26 ++++++++++++++++++++++++++ >> 3 files changed, 28 insertions(+) > >> +++ b/include/block/block_int.h >> @@ -130,6 +130,7 @@ struct BlockDriver { >> int (*bdrv_make_empty)(BlockDriverState *bs); >> >> void (*bdrv_refresh_filename)(BlockDriverState *bs, QDict *options); >> + char *(*bdrv_dirname)(BlockDriverState *bs, Error **errp); > > I know we've been lousy at documentation in the past, but should we > start doing a better job of documenting the contract as we add new > callbacks, rather than just the commit messages? Good point, I'll add a comment. > Based on existing practice, though, I'm okay with: > Reviewed-by: Eric Blake <eblake@redhat.com> Thanks for reviewing! Max
diff --git a/include/block/block.h b/include/block/block.h index eb41956bf1..7bcbd05338 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -439,6 +439,7 @@ char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp); char *bdrv_get_full_backing_filename_from_filename(const char *backed, const char *backing, Error **errp); +char *bdrv_dirname(BlockDriverState *bs, Error **errp); int path_has_protocol(const char *path); int path_is_absolute(const char *path); diff --git a/include/block/block_int.h b/include/block/block_int.h index c1f057ab47..fb916a7890 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -130,6 +130,7 @@ struct BlockDriver { int (*bdrv_make_empty)(BlockDriverState *bs); void (*bdrv_refresh_filename)(BlockDriverState *bs, QDict *options); + char *(*bdrv_dirname)(BlockDriverState *bs, Error **errp); /* aio */ BlockAIOCB *(*bdrv_aio_readv)(BlockDriverState *bs, diff --git a/block.c b/block.c index 2735ec4bcc..e591e326c5 100644 --- a/block.c +++ b/block.c @@ -4083,6 +4083,32 @@ void bdrv_refresh_filename(BlockDriverState *bs) } } +char *bdrv_dirname(BlockDriverState *bs, Error **errp) +{ + BlockDriver *drv = bs->drv; + + if (!drv) { + error_setg(errp, "Node '%s' is ejected", bs->node_name); + return NULL; + } + + if (drv->bdrv_dirname) { + return drv->bdrv_dirname(bs, errp); + } + + if (bs->file) { + return bdrv_dirname(bs->file->bs, errp); + } + + if (bs->exact_filename[0] != '\0') { + return path_combine(bs->exact_filename, ""); + } + + error_setg(errp, "Cannot generate a base directory for %s nodes", + drv->format_name); + return NULL; +} + /* * Hot add/remove a BDS's child. So the user can take a child offline when * it is broken and take a new child online
This function may be implemented by block drivers to derive a directory name from a BDS. Concatenating this g_free()-able string with a relative filename must result in a valid (not necessarily existing) filename, so this is a function that should generally be not implemented by format drivers, because this is protocol-specific. If a BDS's driver does not implement this function, bdrv_dirname() will fall through to the BDS's file if it exists. If it does not, the exact_filename field will be used to generate a directory name. Signed-off-by: Max Reitz <mreitz@redhat.com> --- include/block/block.h | 1 + include/block/block_int.h | 1 + block.c | 26 ++++++++++++++++++++++++++ 3 files changed, 28 insertions(+)