| Message ID | 20231110160804.29021-28-jgross@suse.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | tools: enable xenstore-stubdom to use 9pfs | expand |
Hi Juergen, On 10/11/2023 16:08, Juergen Gross wrote: > Add some helpers for handling filenames which might need different > implementations between stubdom and daemon environments: > > - expansion of relative filenames (those are not really defined today, > just expand them to be relative to /var/lib/xen/xenstore) > - expansion of xenstore_daemon_rundir() (used e.g. for saving the state > file in case of live update - needs to be unchanged in the daemon > case, but should result in /var/lib/xen/xenstore for stubdom) > > Signed-off-by: Juergen Gross <jgross@suse.com> > Reviewed-by: Jason Andryuk <jandryuk@gmail.com> > --- > tools/xenstored/core.c | 9 ++++++++- > tools/xenstored/core.h | 3 +++ > tools/xenstored/lu_daemon.c | 4 ++-- > tools/xenstored/minios.c | 5 +++++ > tools/xenstored/posix.c | 5 +++++ > 5 files changed, 23 insertions(+), 3 deletions(-) > > diff --git a/tools/xenstored/core.c b/tools/xenstored/core.c > index 4a9d874f17..77befd24c9 100644 > --- a/tools/xenstored/core.c > +++ b/tools/xenstored/core.c > @@ -158,6 +158,13 @@ void trace_destroy(const void *data, const char *type) > trace("obj: DESTROY %s %p\n", type, data); > } > > +char *absolute_filename(const void *ctx, const char *filename) Can the return be const? > +{ > + if (filename[0] != '/') > + return talloc_asprintf(ctx, XENSTORE_LIB_DIR "/%s", filename); Looking at the rest of patch, you will be using xenstore_rundir(). I wonder whether it would not be better to switch to xenstore_rundir() so... > + return talloc_strdup(ctx, filename); > +} > + > /** > * Signal handler for SIGHUP, which requests that the trace log is reopened > * (in the main loop). A single byte is written to reopen_log_pipe, to awaken > @@ -2983,7 +2990,7 @@ int main(int argc, char *argv[]) > > signal(SIGHUP, trigger_reopen_log); > if (tracefile) > - tracefile = talloc_strdup(NULL, tracefile); > + tracefile = absolute_filename(NULL, tracefile); > > #ifndef NO_LIVE_UPDATE > /* Read state in case of live update. */ > diff --git a/tools/xenstored/core.h b/tools/xenstored/core.h > index a0d3592961..51e1dddb22 100644 > --- a/tools/xenstored/core.h > +++ b/tools/xenstored/core.h > @@ -393,6 +393,9 @@ void early_init(void); > void mount_9pfs(void); > #endif > > +const char *xenstore_rundir(void); > +char *absolute_filename(const void *ctx, const char *filename); > + > /* Write out the pidfile */ > void write_pidfile(const char *pidfile); > > diff --git a/tools/xenstored/lu_daemon.c b/tools/xenstored/lu_daemon.c > index 71bcabadd3..6351111ab0 100644 > --- a/tools/xenstored/lu_daemon.c > +++ b/tools/xenstored/lu_daemon.c > @@ -24,7 +24,7 @@ void lu_get_dump_state(struct lu_dump_state *state) > state->size = 0; > > state->filename = talloc_asprintf(NULL, "%s/state_dump", > - xenstore_daemon_rundir()); > + xenstore_rundir()); ... call and ... > if (!state->filename) > barf("Allocation failure"); > > @@ -65,7 +65,7 @@ FILE *lu_dump_open(const void *ctx) > int fd; > > filename = talloc_asprintf(ctx, "%s/state_dump", > - xenstore_daemon_rundir()); > + xenstore_rundir()); ... this one could be replaced with absolute_filename(). > if (!filename) > return NULL; > > diff --git a/tools/xenstored/minios.c b/tools/xenstored/minios.c > index fddbede869..cfc2377857 100644 > --- a/tools/xenstored/minios.c > +++ b/tools/xenstored/minios.c > @@ -98,3 +98,8 @@ void mount_9pfs(void) > { > create_thread("mount-9pfs", mount_thread, NULL); > } > + > +const char *xenstore_rundir(void) > +{ > + return XENSTORE_LIB_DIR; > +} > diff --git a/tools/xenstored/posix.c b/tools/xenstored/posix.c > index fcb7791bd7..76f5c9ab84 100644 > --- a/tools/xenstored/posix.c > +++ b/tools/xenstored/posix.c > @@ -168,3 +168,8 @@ void early_init(void) > mkdir(xenstore_daemon_rundir(), 0755); > mkdir(XENSTORE_LIB_DIR, 0755); > } > + > +const char *xenstore_rundir(void) > +{ > + return xenstore_daemon_rundir(); > +} Cheers,
On 13.11.23 23:25, Julien Grall wrote: > Hi Juergen, > > On 10/11/2023 16:08, Juergen Gross wrote: >> Add some helpers for handling filenames which might need different >> implementations between stubdom and daemon environments: >> >> - expansion of relative filenames (those are not really defined today, >> just expand them to be relative to /var/lib/xen/xenstore) >> - expansion of xenstore_daemon_rundir() (used e.g. for saving the state >> file in case of live update - needs to be unchanged in the daemon >> case, but should result in /var/lib/xen/xenstore for stubdom) >> >> Signed-off-by: Juergen Gross <jgross@suse.com> >> Reviewed-by: Jason Andryuk <jandryuk@gmail.com> >> --- >> tools/xenstored/core.c | 9 ++++++++- >> tools/xenstored/core.h | 3 +++ >> tools/xenstored/lu_daemon.c | 4 ++-- >> tools/xenstored/minios.c | 5 +++++ >> tools/xenstored/posix.c | 5 +++++ >> 5 files changed, 23 insertions(+), 3 deletions(-) >> >> diff --git a/tools/xenstored/core.c b/tools/xenstored/core.c >> index 4a9d874f17..77befd24c9 100644 >> --- a/tools/xenstored/core.c >> +++ b/tools/xenstored/core.c >> @@ -158,6 +158,13 @@ void trace_destroy(const void *data, const char *type) >> trace("obj: DESTROY %s %p\n", type, data); >> } >> +char *absolute_filename(const void *ctx, const char *filename) > > Can the return be const? I'll have a look. > >> +{ >> + if (filename[0] != '/') >> + return talloc_asprintf(ctx, XENSTORE_LIB_DIR "/%s", filename); > > Looking at the rest of patch, you will be using xenstore_rundir(). I wonder > whether it would not be better to switch to xenstore_rundir() so... > >> + return talloc_strdup(ctx, filename); >> +} >> + >> /** >> * Signal handler for SIGHUP, which requests that the trace log is reopened >> * (in the main loop). A single byte is written to reopen_log_pipe, to awaken >> @@ -2983,7 +2990,7 @@ int main(int argc, char *argv[]) >> signal(SIGHUP, trigger_reopen_log); >> if (tracefile) >> - tracefile = talloc_strdup(NULL, tracefile); >> + tracefile = absolute_filename(NULL, tracefile); >> #ifndef NO_LIVE_UPDATE >> /* Read state in case of live update. */ >> diff --git a/tools/xenstored/core.h b/tools/xenstored/core.h >> index a0d3592961..51e1dddb22 100644 >> --- a/tools/xenstored/core.h >> +++ b/tools/xenstored/core.h >> @@ -393,6 +393,9 @@ void early_init(void); >> void mount_9pfs(void); >> #endif >> +const char *xenstore_rundir(void); >> +char *absolute_filename(const void *ctx, const char *filename); >> + >> /* Write out the pidfile */ >> void write_pidfile(const char *pidfile); >> diff --git a/tools/xenstored/lu_daemon.c b/tools/xenstored/lu_daemon.c >> index 71bcabadd3..6351111ab0 100644 >> --- a/tools/xenstored/lu_daemon.c >> +++ b/tools/xenstored/lu_daemon.c >> @@ -24,7 +24,7 @@ void lu_get_dump_state(struct lu_dump_state *state) >> state->size = 0; >> state->filename = talloc_asprintf(NULL, "%s/state_dump", >> - xenstore_daemon_rundir()); >> + xenstore_rundir()); > > ... call and ... > >> if (!state->filename) >> barf("Allocation failure"); >> @@ -65,7 +65,7 @@ FILE *lu_dump_open(const void *ctx) >> int fd; >> filename = talloc_asprintf(ctx, "%s/state_dump", >> - xenstore_daemon_rundir()); >> + xenstore_rundir()); > > ... this one could be replaced with absolute_filename(). No, I don't think this is a good idea. I don't want the daemon to store trace files specified as relative files to be stored in /var/run/xen, while I want all files of the stubdom to be stored under /var/lib/xen. Juergen
Hi Juergen, On 14/11/2023 06:45, Juergen Gross wrote: > On 13.11.23 23:25, Julien Grall wrote: >> Hi Juergen, >> >> On 10/11/2023 16:08, Juergen Gross wrote: >>> Add some helpers for handling filenames which might need different >>> implementations between stubdom and daemon environments: >>> >>> - expansion of relative filenames (those are not really defined today, >>> just expand them to be relative to /var/lib/xen/xenstore) >>> - expansion of xenstore_daemon_rundir() (used e.g. for saving the state >>> file in case of live update - needs to be unchanged in the daemon >>> case, but should result in /var/lib/xen/xenstore for stubdom) >>> >>> Signed-off-by: Juergen Gross <jgross@suse.com> >>> Reviewed-by: Jason Andryuk <jandryuk@gmail.com> >>> --- >>> tools/xenstored/core.c | 9 ++++++++- >>> tools/xenstored/core.h | 3 +++ >>> tools/xenstored/lu_daemon.c | 4 ++-- >>> tools/xenstored/minios.c | 5 +++++ >>> tools/xenstored/posix.c | 5 +++++ >>> 5 files changed, 23 insertions(+), 3 deletions(-) >>> >>> diff --git a/tools/xenstored/core.c b/tools/xenstored/core.c >>> index 4a9d874f17..77befd24c9 100644 >>> --- a/tools/xenstored/core.c >>> +++ b/tools/xenstored/core.c >>> @@ -158,6 +158,13 @@ void trace_destroy(const void *data, const char >>> *type) >>> trace("obj: DESTROY %s %p\n", type, data); >>> } >>> +char *absolute_filename(const void *ctx, const char *filename) >> >> Can the return be const? > > I'll have a look. > >> >>> +{ >>> + if (filename[0] != '/') >>> + return talloc_asprintf(ctx, XENSTORE_LIB_DIR "/%s", filename); >> >> Looking at the rest of patch, you will be using xenstore_rundir(). I >> wonder whether it would not be better to switch to xenstore_rundir() >> so... >> >>> + return talloc_strdup(ctx, filename); >>> +} >>> + >>> /** >>> * Signal handler for SIGHUP, which requests that the trace log is >>> reopened >>> * (in the main loop). A single byte is written to >>> reopen_log_pipe, to awaken >>> @@ -2983,7 +2990,7 @@ int main(int argc, char *argv[]) >>> signal(SIGHUP, trigger_reopen_log); >>> if (tracefile) >>> - tracefile = talloc_strdup(NULL, tracefile); >>> + tracefile = absolute_filename(NULL, tracefile); >>> #ifndef NO_LIVE_UPDATE >>> /* Read state in case of live update. */ >>> diff --git a/tools/xenstored/core.h b/tools/xenstored/core.h >>> index a0d3592961..51e1dddb22 100644 >>> --- a/tools/xenstored/core.h >>> +++ b/tools/xenstored/core.h >>> @@ -393,6 +393,9 @@ void early_init(void); >>> void mount_9pfs(void); >>> #endif >>> +const char *xenstore_rundir(void); >>> +char *absolute_filename(const void *ctx, const char *filename); >>> + >>> /* Write out the pidfile */ >>> void write_pidfile(const char *pidfile); >>> diff --git a/tools/xenstored/lu_daemon.c b/tools/xenstored/lu_daemon.c >>> index 71bcabadd3..6351111ab0 100644 >>> --- a/tools/xenstored/lu_daemon.c >>> +++ b/tools/xenstored/lu_daemon.c >>> @@ -24,7 +24,7 @@ void lu_get_dump_state(struct lu_dump_state *state) >>> state->size = 0; >>> state->filename = talloc_asprintf(NULL, "%s/state_dump", >>> - xenstore_daemon_rundir()); >>> + xenstore_rundir()); >> >> ... call and ... >> >>> if (!state->filename) >>> barf("Allocation failure"); >>> @@ -65,7 +65,7 @@ FILE *lu_dump_open(const void *ctx) >>> int fd; >>> filename = talloc_asprintf(ctx, "%s/state_dump", >>> - xenstore_daemon_rundir()); >>> + xenstore_rundir()); >> >> ... this one could be replaced with absolute_filename(). > > No, I don't think this is a good idea. > > I don't want the daemon to store trace files specified as relative files > to be stored in /var/run/xen, while I want all files of the stubdom to be > stored under /var/lib/xen. Why? This is a bit odd to have a different behavior between stubdom and daemon. It would be much easier for the user if they knew all the files would be at the same place regardless the version used. Also, regarding the background of my question. You are introducing a function call absolute_filename(). From the name, there is nothing indicating that this should only be used for trace files. If this is only indented for tracefile, then I think this should be renamed to something like absolute_tracefile(...). Cheers,
On 14.11.23 10:10, Julien Grall wrote: > Hi Juergen, > > On 14/11/2023 06:45, Juergen Gross wrote: >> On 13.11.23 23:25, Julien Grall wrote: >>> Hi Juergen, >>> >>> On 10/11/2023 16:08, Juergen Gross wrote: >>>> Add some helpers for handling filenames which might need different >>>> implementations between stubdom and daemon environments: >>>> >>>> - expansion of relative filenames (those are not really defined today, >>>> just expand them to be relative to /var/lib/xen/xenstore) >>>> - expansion of xenstore_daemon_rundir() (used e.g. for saving the state >>>> file in case of live update - needs to be unchanged in the daemon >>>> case, but should result in /var/lib/xen/xenstore for stubdom) >>>> >>>> Signed-off-by: Juergen Gross <jgross@suse.com> >>>> Reviewed-by: Jason Andryuk <jandryuk@gmail.com> >>>> --- >>>> tools/xenstored/core.c | 9 ++++++++- >>>> tools/xenstored/core.h | 3 +++ >>>> tools/xenstored/lu_daemon.c | 4 ++-- >>>> tools/xenstored/minios.c | 5 +++++ >>>> tools/xenstored/posix.c | 5 +++++ >>>> 5 files changed, 23 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/tools/xenstored/core.c b/tools/xenstored/core.c >>>> index 4a9d874f17..77befd24c9 100644 >>>> --- a/tools/xenstored/core.c >>>> +++ b/tools/xenstored/core.c >>>> @@ -158,6 +158,13 @@ void trace_destroy(const void *data, const char *type) >>>> trace("obj: DESTROY %s %p\n", type, data); >>>> } >>>> +char *absolute_filename(const void *ctx, const char *filename) >>> >>> Can the return be const? >> >> I'll have a look. >> >>> >>>> +{ >>>> + if (filename[0] != '/') >>>> + return talloc_asprintf(ctx, XENSTORE_LIB_DIR "/%s", filename); >>> >>> Looking at the rest of patch, you will be using xenstore_rundir(). I wonder >>> whether it would not be better to switch to xenstore_rundir() so... >>> >>>> + return talloc_strdup(ctx, filename); >>>> +} >>>> + >>>> /** >>>> * Signal handler for SIGHUP, which requests that the trace log is reopened >>>> * (in the main loop). A single byte is written to reopen_log_pipe, to >>>> awaken >>>> @@ -2983,7 +2990,7 @@ int main(int argc, char *argv[]) >>>> signal(SIGHUP, trigger_reopen_log); >>>> if (tracefile) >>>> - tracefile = talloc_strdup(NULL, tracefile); >>>> + tracefile = absolute_filename(NULL, tracefile); >>>> #ifndef NO_LIVE_UPDATE >>>> /* Read state in case of live update. */ >>>> diff --git a/tools/xenstored/core.h b/tools/xenstored/core.h >>>> index a0d3592961..51e1dddb22 100644 >>>> --- a/tools/xenstored/core.h >>>> +++ b/tools/xenstored/core.h >>>> @@ -393,6 +393,9 @@ void early_init(void); >>>> void mount_9pfs(void); >>>> #endif >>>> +const char *xenstore_rundir(void); >>>> +char *absolute_filename(const void *ctx, const char *filename); >>>> + >>>> /* Write out the pidfile */ >>>> void write_pidfile(const char *pidfile); >>>> diff --git a/tools/xenstored/lu_daemon.c b/tools/xenstored/lu_daemon.c >>>> index 71bcabadd3..6351111ab0 100644 >>>> --- a/tools/xenstored/lu_daemon.c >>>> +++ b/tools/xenstored/lu_daemon.c >>>> @@ -24,7 +24,7 @@ void lu_get_dump_state(struct lu_dump_state *state) >>>> state->size = 0; >>>> state->filename = talloc_asprintf(NULL, "%s/state_dump", >>>> - xenstore_daemon_rundir()); >>>> + xenstore_rundir()); >>> >>> ... call and ... >>> >>>> if (!state->filename) >>>> barf("Allocation failure"); >>>> @@ -65,7 +65,7 @@ FILE *lu_dump_open(const void *ctx) >>>> int fd; >>>> filename = talloc_asprintf(ctx, "%s/state_dump", >>>> - xenstore_daemon_rundir()); >>>> + xenstore_rundir()); >>> >>> ... this one could be replaced with absolute_filename(). >> >> No, I don't think this is a good idea. >> >> I don't want the daemon to store trace files specified as relative files >> to be stored in /var/run/xen, while I want all files of the stubdom to be >> stored under /var/lib/xen. > > Why? This is a bit odd to have a different behavior between stubdom and daemon. > It would be much easier for the user if they knew all the files would be at the > same place regardless the version used. The main difference is that stubdom has access to only _one_ directory in dom0. I /could/ give it access to "/", but do we really want that? We can't get rid of the /var/run/xen access in xenstored, as it is used for live update, so the old and the new xenstored need to agree on the location of the state file. And we can't drop the possibility of specifying absolute paths for e.g. trace files, as those might be in use by users already. > Also, regarding the background of my question. You are introducing a function > call absolute_filename(). From the name, there is nothing indicating that this > should only be used for trace files. If this is only indented for tracefile, > then I think this should be renamed to something like absolute_tracefile(...). After the last patch of this series "xenstore-control memreport <file>" will use it, too. Juergen
Hi Juergen, On 14/11/2023 09:26, Juergen Gross wrote: > On 14.11.23 10:10, Julien Grall wrote: >> Hi Juergen, >> >> On 14/11/2023 06:45, Juergen Gross wrote: >>> On 13.11.23 23:25, Julien Grall wrote: >>>> Hi Juergen, >>>> >>>> On 10/11/2023 16:08, Juergen Gross wrote: >>>>> Add some helpers for handling filenames which might need different >>>>> implementations between stubdom and daemon environments: >>>>> >>>>> - expansion of relative filenames (those are not really defined today, >>>>> just expand them to be relative to /var/lib/xen/xenstore) >>>>> - expansion of xenstore_daemon_rundir() (used e.g. for saving the >>>>> state >>>>> file in case of live update - needs to be unchanged in the daemon >>>>> case, but should result in /var/lib/xen/xenstore for stubdom) >>>>> >>>>> Signed-off-by: Juergen Gross <jgross@suse.com> >>>>> Reviewed-by: Jason Andryuk <jandryuk@gmail.com> >>>>> --- >>>>> tools/xenstored/core.c | 9 ++++++++- >>>>> tools/xenstored/core.h | 3 +++ >>>>> tools/xenstored/lu_daemon.c | 4 ++-- >>>>> tools/xenstored/minios.c | 5 +++++ >>>>> tools/xenstored/posix.c | 5 +++++ >>>>> 5 files changed, 23 insertions(+), 3 deletions(-) >>>>> >>>>> diff --git a/tools/xenstored/core.c b/tools/xenstored/core.c >>>>> index 4a9d874f17..77befd24c9 100644 >>>>> --- a/tools/xenstored/core.c >>>>> +++ b/tools/xenstored/core.c >>>>> @@ -158,6 +158,13 @@ void trace_destroy(const void *data, const >>>>> char *type) >>>>> trace("obj: DESTROY %s %p\n", type, data); >>>>> } >>>>> +char *absolute_filename(const void *ctx, const char *filename) >>>> >>>> Can the return be const? >>> >>> I'll have a look. >>> >>>> >>>>> +{ >>>>> + if (filename[0] != '/') >>>>> + return talloc_asprintf(ctx, XENSTORE_LIB_DIR "/%s", >>>>> filename); >>>> >>>> Looking at the rest of patch, you will be using xenstore_rundir(). I >>>> wonder whether it would not be better to switch to xenstore_rundir() >>>> so... >>>> >>>>> + return talloc_strdup(ctx, filename); >>>>> +} >>>>> + >>>>> /** >>>>> * Signal handler for SIGHUP, which requests that the trace log >>>>> is reopened >>>>> * (in the main loop). A single byte is written to >>>>> reopen_log_pipe, to awaken >>>>> @@ -2983,7 +2990,7 @@ int main(int argc, char *argv[]) >>>>> signal(SIGHUP, trigger_reopen_log); >>>>> if (tracefile) >>>>> - tracefile = talloc_strdup(NULL, tracefile); >>>>> + tracefile = absolute_filename(NULL, tracefile); >>>>> #ifndef NO_LIVE_UPDATE >>>>> /* Read state in case of live update. */ >>>>> diff --git a/tools/xenstored/core.h b/tools/xenstored/core.h >>>>> index a0d3592961..51e1dddb22 100644 >>>>> --- a/tools/xenstored/core.h >>>>> +++ b/tools/xenstored/core.h >>>>> @@ -393,6 +393,9 @@ void early_init(void); >>>>> void mount_9pfs(void); >>>>> #endif >>>>> +const char *xenstore_rundir(void); >>>>> +char *absolute_filename(const void *ctx, const char *filename); >>>>> + >>>>> /* Write out the pidfile */ >>>>> void write_pidfile(const char *pidfile); >>>>> diff --git a/tools/xenstored/lu_daemon.c b/tools/xenstored/lu_daemon.c >>>>> index 71bcabadd3..6351111ab0 100644 >>>>> --- a/tools/xenstored/lu_daemon.c >>>>> +++ b/tools/xenstored/lu_daemon.c >>>>> @@ -24,7 +24,7 @@ void lu_get_dump_state(struct lu_dump_state *state) >>>>> state->size = 0; >>>>> state->filename = talloc_asprintf(NULL, "%s/state_dump", >>>>> - xenstore_daemon_rundir()); >>>>> + xenstore_rundir()); >>>> >>>> ... call and ... >>>> >>>>> if (!state->filename) >>>>> barf("Allocation failure"); >>>>> @@ -65,7 +65,7 @@ FILE *lu_dump_open(const void *ctx) >>>>> int fd; >>>>> filename = talloc_asprintf(ctx, "%s/state_dump", >>>>> - xenstore_daemon_rundir()); >>>>> + xenstore_rundir()); >>>> >>>> ... this one could be replaced with absolute_filename(). >>> >>> No, I don't think this is a good idea. >>> >>> I don't want the daemon to store trace files specified as relative files >>> to be stored in /var/run/xen, while I want all files of the stubdom >>> to be >>> stored under /var/lib/xen. >> >> Why? This is a bit odd to have a different behavior between stubdom >> and daemon. It would be much easier for the user if they knew all the >> files would be at the same place regardless the version used. > > The main difference is that stubdom has access to only _one_ directory > in dom0. Would you be able to explain why we can only give access to a single directory? Is this because of the 9pfs protocol? > I /could/ give it access to "/", but do we really want that? I don't think we want to give access to "/". > > We can't get rid of the /var/run/xen access in xenstored, as it is used for > live update, so the old and the new xenstored need to agree on the > location of > the state file. Well, Xenstored Live-Update is technically a tech preview feature. So we *could* break it and allow the state file to be specified on the command line. Anyway, I am ok if you want them to have the live-update state in a separate however... > And we can't drop the possibility of specifying absolute > paths > for e.g. trace files, as those might be in use by users already. > >> Also, regarding the background of my question. You are introducing a >> function call absolute_filename(). From the name, there is nothing >> indicating that this should only be used for trace files. If this is >> only indented for tracefile, then I think this should be renamed to >> something like absolute_tracefile(...). > > After the last patch of this series "xenstore-control memreport <file>" > will use > it, too. ... this doesn't change my point here. The function name doesn't *tell* me why it can't be used for live-update files. If this can't be clarified in the name, then it should be clarified in a comment. Maybe one top of the Live-Update code. Cheers,
On 14.11.23 21:53, Julien Grall wrote: > Hi Juergen, > > On 14/11/2023 09:26, Juergen Gross wrote: >> On 14.11.23 10:10, Julien Grall wrote: >>> Hi Juergen, >>> >>> On 14/11/2023 06:45, Juergen Gross wrote: >>>> On 13.11.23 23:25, Julien Grall wrote: >>>>> Hi Juergen, >>>>> >>>>> On 10/11/2023 16:08, Juergen Gross wrote: >>>>>> Add some helpers for handling filenames which might need different >>>>>> implementations between stubdom and daemon environments: >>>>>> >>>>>> - expansion of relative filenames (those are not really defined today, >>>>>> just expand them to be relative to /var/lib/xen/xenstore) >>>>>> - expansion of xenstore_daemon_rundir() (used e.g. for saving the state >>>>>> file in case of live update - needs to be unchanged in the daemon >>>>>> case, but should result in /var/lib/xen/xenstore for stubdom) >>>>>> >>>>>> Signed-off-by: Juergen Gross <jgross@suse.com> >>>>>> Reviewed-by: Jason Andryuk <jandryuk@gmail.com> >>>>>> --- >>>>>> tools/xenstored/core.c | 9 ++++++++- >>>>>> tools/xenstored/core.h | 3 +++ >>>>>> tools/xenstored/lu_daemon.c | 4 ++-- >>>>>> tools/xenstored/minios.c | 5 +++++ >>>>>> tools/xenstored/posix.c | 5 +++++ >>>>>> 5 files changed, 23 insertions(+), 3 deletions(-) >>>>>> >>>>>> diff --git a/tools/xenstored/core.c b/tools/xenstored/core.c >>>>>> index 4a9d874f17..77befd24c9 100644 >>>>>> --- a/tools/xenstored/core.c >>>>>> +++ b/tools/xenstored/core.c >>>>>> @@ -158,6 +158,13 @@ void trace_destroy(const void *data, const char *type) >>>>>> trace("obj: DESTROY %s %p\n", type, data); >>>>>> } >>>>>> +char *absolute_filename(const void *ctx, const char *filename) >>>>> >>>>> Can the return be const? >>>> >>>> I'll have a look. >>>> >>>>> >>>>>> +{ >>>>>> + if (filename[0] != '/') >>>>>> + return talloc_asprintf(ctx, XENSTORE_LIB_DIR "/%s", filename); >>>>> >>>>> Looking at the rest of patch, you will be using xenstore_rundir(). I wonder >>>>> whether it would not be better to switch to xenstore_rundir() so... >>>>> >>>>>> + return talloc_strdup(ctx, filename); >>>>>> +} >>>>>> + >>>>>> /** >>>>>> * Signal handler for SIGHUP, which requests that the trace log is reopened >>>>>> * (in the main loop). A single byte is written to reopen_log_pipe, to >>>>>> awaken >>>>>> @@ -2983,7 +2990,7 @@ int main(int argc, char *argv[]) >>>>>> signal(SIGHUP, trigger_reopen_log); >>>>>> if (tracefile) >>>>>> - tracefile = talloc_strdup(NULL, tracefile); >>>>>> + tracefile = absolute_filename(NULL, tracefile); >>>>>> #ifndef NO_LIVE_UPDATE >>>>>> /* Read state in case of live update. */ >>>>>> diff --git a/tools/xenstored/core.h b/tools/xenstored/core.h >>>>>> index a0d3592961..51e1dddb22 100644 >>>>>> --- a/tools/xenstored/core.h >>>>>> +++ b/tools/xenstored/core.h >>>>>> @@ -393,6 +393,9 @@ void early_init(void); >>>>>> void mount_9pfs(void); >>>>>> #endif >>>>>> +const char *xenstore_rundir(void); >>>>>> +char *absolute_filename(const void *ctx, const char *filename); >>>>>> + >>>>>> /* Write out the pidfile */ >>>>>> void write_pidfile(const char *pidfile); >>>>>> diff --git a/tools/xenstored/lu_daemon.c b/tools/xenstored/lu_daemon.c >>>>>> index 71bcabadd3..6351111ab0 100644 >>>>>> --- a/tools/xenstored/lu_daemon.c >>>>>> +++ b/tools/xenstored/lu_daemon.c >>>>>> @@ -24,7 +24,7 @@ void lu_get_dump_state(struct lu_dump_state *state) >>>>>> state->size = 0; >>>>>> state->filename = talloc_asprintf(NULL, "%s/state_dump", >>>>>> - xenstore_daemon_rundir()); >>>>>> + xenstore_rundir()); >>>>> >>>>> ... call and ... >>>>> >>>>>> if (!state->filename) >>>>>> barf("Allocation failure"); >>>>>> @@ -65,7 +65,7 @@ FILE *lu_dump_open(const void *ctx) >>>>>> int fd; >>>>>> filename = talloc_asprintf(ctx, "%s/state_dump", >>>>>> - xenstore_daemon_rundir()); >>>>>> + xenstore_rundir()); >>>>> >>>>> ... this one could be replaced with absolute_filename(). >>>> >>>> No, I don't think this is a good idea. >>>> >>>> I don't want the daemon to store trace files specified as relative files >>>> to be stored in /var/run/xen, while I want all files of the stubdom to be >>>> stored under /var/lib/xen. >>> >>> Why? This is a bit odd to have a different behavior between stubdom and >>> daemon. It would be much easier for the user if they knew all the files would >>> be at the same place regardless the version used. >> >> The main difference is that stubdom has access to only _one_ directory in dom0. > > Would you be able to explain why we can only give access to a single directory? > Is this because of the 9pfs protocol? Yes. I can mount a specific dom0 directory in the guest. > >> I /could/ give it access to "/", but do we really want that? > > I don't think we want to give access to "/". > >> >> We can't get rid of the /var/run/xen access in xenstored, as it is used for >> live update, so the old and the new xenstored need to agree on the location of >> the state file. > > Well, Xenstored Live-Update is technically a tech preview feature. So we *could* > break it and allow the state file to be specified on the command line. > > Anyway, I am ok if you want them to have the live-update state in a separate > however... > > >> And we can't drop the possibility of specifying absolute paths >> for e.g. trace files, as those might be in use by users already. >> >>> Also, regarding the background of my question. You are introducing a function >>> call absolute_filename(). From the name, there is nothing indicating that >>> this should only be used for trace files. If this is only indented for >>> tracefile, then I think this should be renamed to something like >>> absolute_tracefile(...). >> >> After the last patch of this series "xenstore-control memreport <file>" will use >> it, too. > > ... this doesn't change my point here. The function name doesn't *tell* me why > it can't be used for live-update files. > > If this can't be clarified in the name, then it should be clarified in a > comment. Maybe one top of the Live-Update code. I think a comment before the absolute_filename() function would be the best fit. Juergen
On Wed, Nov 15, 2023 at 1:14 AM Juergen Gross <jgross@suse.com> wrote: > > On 14.11.23 21:53, Julien Grall wrote: > > Hi Juergen, > > > > On 14/11/2023 09:26, Juergen Gross wrote: > >> On 14.11.23 10:10, Julien Grall wrote: > >>> Hi Juergen, > >>> > >>> On 14/11/2023 06:45, Juergen Gross wrote: > >>>> On 13.11.23 23:25, Julien Grall wrote: > >>>>> Hi Juergen, > >>>>> > >>>>> On 10/11/2023 16:08, Juergen Gross wrote: > >>>>>> diff --git a/tools/xenstored/lu_daemon.c b/tools/xenstored/lu_daemon.c > >>>>>> index 71bcabadd3..6351111ab0 100644 > >>>>>> --- a/tools/xenstored/lu_daemon.c > >>>>>> +++ b/tools/xenstored/lu_daemon.c > >>>>>> @@ -24,7 +24,7 @@ void lu_get_dump_state(struct lu_dump_state *state) > >>>>>> state->size = 0; > >>>>>> state->filename = talloc_asprintf(NULL, "%s/state_dump", > >>>>>> - xenstore_daemon_rundir()); > >>>>>> + xenstore_rundir()); > >>>>> > >>>>> ... call and ... > >>>>> > >>>>>> if (!state->filename) > >>>>>> barf("Allocation failure"); > >>>>>> @@ -65,7 +65,7 @@ FILE *lu_dump_open(const void *ctx) > >>>>>> int fd; > >>>>>> filename = talloc_asprintf(ctx, "%s/state_dump", > >>>>>> - xenstore_daemon_rundir()); > >>>>>> + xenstore_rundir()); > >>>>> > >>>>> ... this one could be replaced with absolute_filename(). > >>>> > >>>> No, I don't think this is a good idea. > >>>> > >>>> I don't want the daemon to store trace files specified as relative files > >>>> to be stored in /var/run/xen, while I want all files of the stubdom to be > >>>> stored under /var/lib/xen. > >>> > >>> Why? This is a bit odd to have a different behavior between stubdom and > >>> daemon. It would be much easier for the user if they knew all the files would > >>> be at the same place regardless the version used. > >> > >> The main difference is that stubdom has access to only _one_ directory in dom0. > > > > Would you be able to explain why we can only give access to a single directory? > > Is this because of the 9pfs protocol? > > Yes. I can mount a specific dom0 directory in the guest. I'm fine with a single directory being used for stubdom. Two directories could be exported, and mini-os would need to use the "tag" to differentiate the two. That may not be worth the added code. QEMU can provide multiple 9pfs exports and Linux can mount them by tag name. Regards, Jason
On 28.11.23 21:42, Jason Andryuk wrote: > On Wed, Nov 15, 2023 at 1:14 AM Juergen Gross <jgross@suse.com> wrote: >> >> On 14.11.23 21:53, Julien Grall wrote: >>> Hi Juergen, >>> >>> On 14/11/2023 09:26, Juergen Gross wrote: >>>> On 14.11.23 10:10, Julien Grall wrote: >>>>> Hi Juergen, >>>>> >>>>> On 14/11/2023 06:45, Juergen Gross wrote: >>>>>> On 13.11.23 23:25, Julien Grall wrote: >>>>>>> Hi Juergen, >>>>>>> >>>>>>> On 10/11/2023 16:08, Juergen Gross wrote: >>>>>>>> diff --git a/tools/xenstored/lu_daemon.c b/tools/xenstored/lu_daemon.c >>>>>>>> index 71bcabadd3..6351111ab0 100644 >>>>>>>> --- a/tools/xenstored/lu_daemon.c >>>>>>>> +++ b/tools/xenstored/lu_daemon.c >>>>>>>> @@ -24,7 +24,7 @@ void lu_get_dump_state(struct lu_dump_state *state) >>>>>>>> state->size = 0; >>>>>>>> state->filename = talloc_asprintf(NULL, "%s/state_dump", >>>>>>>> - xenstore_daemon_rundir()); >>>>>>>> + xenstore_rundir()); >>>>>>> >>>>>>> ... call and ... >>>>>>> >>>>>>>> if (!state->filename) >>>>>>>> barf("Allocation failure"); >>>>>>>> @@ -65,7 +65,7 @@ FILE *lu_dump_open(const void *ctx) >>>>>>>> int fd; >>>>>>>> filename = talloc_asprintf(ctx, "%s/state_dump", >>>>>>>> - xenstore_daemon_rundir()); >>>>>>>> + xenstore_rundir()); >>>>>>> >>>>>>> ... this one could be replaced with absolute_filename(). >>>>>> >>>>>> No, I don't think this is a good idea. >>>>>> >>>>>> I don't want the daemon to store trace files specified as relative files >>>>>> to be stored in /var/run/xen, while I want all files of the stubdom to be >>>>>> stored under /var/lib/xen. >>>>> >>>>> Why? This is a bit odd to have a different behavior between stubdom and >>>>> daemon. It would be much easier for the user if they knew all the files would >>>>> be at the same place regardless the version used. >>>> >>>> The main difference is that stubdom has access to only _one_ directory in dom0. >>> >>> Would you be able to explain why we can only give access to a single directory? >>> Is this because of the 9pfs protocol? >> >> Yes. I can mount a specific dom0 directory in the guest. > > I'm fine with a single directory being used for stubdom. Two > directories could be exported, and mini-os would need to use the "tag" > to differentiate the two. That may not be worth the added code. QEMU > can provide multiple 9pfs exports and Linux can mount them by tag > name. The main thing is that the daemon is meant to solve exactly one problem: having a way to enable infrastructure domains (Xenstore-stubdom, driver domains, device-model stubdoms) to access some few files in dom0, e.g. for logging or config purposes. The daemon should be as simple as possible and, of course, have ways to control resource usage (file system space) used by the domUs configured to use it. It should _not_ be a a replacement of the full-blown backend in e.g. qemu. Juergen
diff --git a/tools/xenstored/core.c b/tools/xenstored/core.c index 4a9d874f17..77befd24c9 100644 --- a/tools/xenstored/core.c +++ b/tools/xenstored/core.c @@ -158,6 +158,13 @@ void trace_destroy(const void *data, const char *type) trace("obj: DESTROY %s %p\n", type, data); } +char *absolute_filename(const void *ctx, const char *filename) +{ + if (filename[0] != '/') + return talloc_asprintf(ctx, XENSTORE_LIB_DIR "/%s", filename); + return talloc_strdup(ctx, filename); +} + /** * Signal handler for SIGHUP, which requests that the trace log is reopened * (in the main loop). A single byte is written to reopen_log_pipe, to awaken @@ -2983,7 +2990,7 @@ int main(int argc, char *argv[]) signal(SIGHUP, trigger_reopen_log); if (tracefile) - tracefile = talloc_strdup(NULL, tracefile); + tracefile = absolute_filename(NULL, tracefile); #ifndef NO_LIVE_UPDATE /* Read state in case of live update. */ diff --git a/tools/xenstored/core.h b/tools/xenstored/core.h index a0d3592961..51e1dddb22 100644 --- a/tools/xenstored/core.h +++ b/tools/xenstored/core.h @@ -393,6 +393,9 @@ void early_init(void); void mount_9pfs(void); #endif +const char *xenstore_rundir(void); +char *absolute_filename(const void *ctx, const char *filename); + /* Write out the pidfile */ void write_pidfile(const char *pidfile); diff --git a/tools/xenstored/lu_daemon.c b/tools/xenstored/lu_daemon.c index 71bcabadd3..6351111ab0 100644 --- a/tools/xenstored/lu_daemon.c +++ b/tools/xenstored/lu_daemon.c @@ -24,7 +24,7 @@ void lu_get_dump_state(struct lu_dump_state *state) state->size = 0; state->filename = talloc_asprintf(NULL, "%s/state_dump", - xenstore_daemon_rundir()); + xenstore_rundir()); if (!state->filename) barf("Allocation failure"); @@ -65,7 +65,7 @@ FILE *lu_dump_open(const void *ctx) int fd; filename = talloc_asprintf(ctx, "%s/state_dump", - xenstore_daemon_rundir()); + xenstore_rundir()); if (!filename) return NULL; diff --git a/tools/xenstored/minios.c b/tools/xenstored/minios.c index fddbede869..cfc2377857 100644 --- a/tools/xenstored/minios.c +++ b/tools/xenstored/minios.c @@ -98,3 +98,8 @@ void mount_9pfs(void) { create_thread("mount-9pfs", mount_thread, NULL); } + +const char *xenstore_rundir(void) +{ + return XENSTORE_LIB_DIR; +} diff --git a/tools/xenstored/posix.c b/tools/xenstored/posix.c index fcb7791bd7..76f5c9ab84 100644 --- a/tools/xenstored/posix.c +++ b/tools/xenstored/posix.c @@ -168,3 +168,8 @@ void early_init(void) mkdir(xenstore_daemon_rundir(), 0755); mkdir(XENSTORE_LIB_DIR, 0755); } + +const char *xenstore_rundir(void) +{ + return xenstore_daemon_rundir(); +}