[dm-devel] [PATCH v2 1/7] libmultipath: make dm_get_map/status return codes symbolic
Benjamin Marzinski
bmarzins at redhat.com
Thu Jul 2 18:33:34 UTC 2020
On Wed, Jul 01, 2020 at 08:15:49PM +0000, Martin Wilck wrote:
> On Thu, 2020-06-25 at 15:42 -0500, Benjamin Marzinski wrote:
> > dm_get_map() and dm_get_status() now use symbolic return codes. They
> > also differentiate between failing to get information from device-
> > mapper
> > and not finding the requested device. These symboilc return codes are
> > also used by update_multipath_* functions.
> >
> > Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
> > ---
> > libmultipath/devmapper.c | 51 +++++++++++++++++++++++++-----------
> > --
> > libmultipath/devmapper.h | 6 +++++
> > libmultipath/structs_vec.c | 45 +++++++++++++++++++--------------
> > multipathd/main.c | 12 ++++-----
> > 4 files changed, 72 insertions(+), 42 deletions(-)
> >
> > diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c
> > index 27d52398..f5cfe296 100644
> > --- a/libmultipath/devmapper.c
> > +++ b/libmultipath/devmapper.c
> > @@ -534,36 +534,43 @@ int dm_map_present(const char * str)
> >
> > int dm_get_map(const char *name, unsigned long long *size, char
> > *outparams)
> > {
> > - int r = 1;
> > + int r = DMP_ERR;
> > struct dm_task *dmt;
> > uint64_t start, length;
> > char *target_type = NULL;
> > char *params = NULL;
> >
> > if (!(dmt = libmp_dm_task_create(DM_DEVICE_TABLE)))
> > - return 1;
> > + return r;
> >
> > if (!dm_task_set_name(dmt, name))
> > goto out;
> >
> > dm_task_no_open_count(dmt);
> >
> > - if (!dm_task_run(dmt))
> > + errno = 0;
> > + if (!dm_task_run(dmt)) {
> > + if (errno == ENXIO)
>
> Don't you have to use dm_task_get_errno(dmt) here?
> errno might have been overwritten... if you are certain you don't need
> it, a comment explaining it would be helpful.
Err.. I didn't know that existed. Sure I can use it, and your other
suggestions are reasonable as well
-Ben
>
>
> > + r = DMP_FAIL;
>
> You've created generic names, which is good, but these are perhaps a
> bit too generic. What's the difference bewteen DMP_FAIL and DMP_ERR? I
> can derive it from your code, but it's not obvious from the retcode
> names, and thus doesn't help the reader much. I suggest to keep DMT_ERR
> to denote a "generic" error condition, and use e.g. DMP_NOTFOUND for
> the other case.
>
> > goto out;
> > + }
> >
> > + r = DMP_FAIL;
> > /* Fetch 1st target */
> > - dm_get_next_target(dmt, NULL, &start, &length,
> > - &target_type, ¶ms);
> > + if (dm_get_next_target(dmt, NULL, &start, &length,
> > + &target_type, ¶ms) != NULL)
> > + /* more than one target */
> > + goto out;
> >
> > if (size)
> > *size = length;
> >
> > if (!outparams) {
> > - r = 0;
> > + r = DMP_PASS;
>
> Nit: DMP_OK or DMP_SUCCESS would be more conventional for successful
> completion. "pass" sounds like something more specific to me,
> like having passed a test or a filter.
>
> > goto out;
> > }
> > if (snprintf(outparams, PARAMS_SIZE, "%s", params) <=
> > PARAMS_SIZE)
> > - r = 0;
> > + r = DMP_PASS;
> > out:
> > dm_task_destroy(dmt);
> > return r;
> > @@ -637,35 +644,45 @@ is_mpath_part(const char *part_name, const char
> > *map_name)
> >
> > int dm_get_status(const char *name, char *outstatus)
> > {
> > - int r = 1;
> > + int r = DMP_ERR;
> > struct dm_task *dmt;
> > uint64_t start, length;
> > char *target_type = NULL;
> > char *status = NULL;
> >
> > if (!(dmt = libmp_dm_task_create(DM_DEVICE_STATUS)))
> > - return 1;
> > + return r;
> >
> > if (!dm_task_set_name(dmt, name))
> > goto out;
> >
> > dm_task_no_open_count(dmt);
> >
> > - if (!dm_task_run(dmt))
> > + errno = 0;
> > + if (!dm_task_run(dmt)) {
> > + if (errno == ENXIO)
> > + r = DMP_FAIL;
> > goto out;
> > + }
>
> see above
>
> >
> > + r = DMP_FAIL;
> > /* Fetch 1st target */
> > - dm_get_next_target(dmt, NULL, &start, &length,
> > - &target_type, &status);
> > + if (dm_get_next_target(dmt, NULL, &start, &length,
> > + &target_type, &status) != NULL)
> > + goto out;
> > +
> > + if (!target_type || strcmp(target_type, TGT_MPATH) != 0)
> > + goto out;
> > +
> > if (!status) {
> > condlog(2, "get null status.");
> > goto out;
> > }
> >
> > if (snprintf(outstatus, PARAMS_SIZE, "%s", status) <=
> > PARAMS_SIZE)
> > - r = 0;
> > + r = DMP_PASS;
> > out:
> > - if (r)
> > + if (r != DMP_PASS)
> > condlog(0, "%s: error getting map status string",
> > name);
> >
> > dm_task_destroy(dmt);
> > @@ -920,7 +937,7 @@ int _dm_flush_map (const char * mapname, int
> > need_sync, int deferred_remove,
> > return 1;
> >
> > if (need_suspend &&
> > - !dm_get_map(mapname, &mapsize, params) &&
> > + dm_get_map(mapname, &mapsize, params) == DMP_PASS &&
> > strstr(params, "queue_if_no_path")) {
> > if (!dm_queue_if_no_path(mapname, 0))
> > queue_if_no_path = 1;
> > @@ -1129,7 +1146,7 @@ struct multipath *dm_get_multipath(const char
> > *name)
> > if (!mpp->alias)
> > goto out;
> >
> > - if (dm_get_map(name, &mpp->size, NULL))
> > + if (dm_get_map(name, &mpp->size, NULL) != DMP_PASS)
> > goto out;
> >
> > dm_get_uuid(name, mpp->wwid, WWID_SIZE);
> > @@ -1313,7 +1330,7 @@ do_foreach_partmaps (const char * mapname,
> > /*
> > * and we can fetch the map table from the kernel
> > */
> > - !dm_get_map(names->name, &size, ¶ms[0]) &&
> > + dm_get_map(names->name, &size, ¶ms[0]) ==
> > DMP_PASS &&
> >
> > /*
> > * and the table maps over the multipath map
> > diff --git a/libmultipath/devmapper.h b/libmultipath/devmapper.h
> > index 5ed7edc5..5b18bf4b 100644
> > --- a/libmultipath/devmapper.h
> > +++ b/libmultipath/devmapper.h
> > @@ -27,6 +27,12 @@
> > #define UUID_PREFIX "mpath-"
> > #define UUID_PREFIX_LEN (sizeof(UUID_PREFIX) - 1)
> >
> > +enum {
> > + DMP_ERR = -1,
> > + DMP_PASS,
> > + DMP_FAIL,
> > +};
> > +
>
> Nit: Why use both negative and positive numbers? It's not important,
> but I feel that unless we really want to treat DM_ERR in a very special
> way, it would be better to use only positive values. (Actually, if we
> go for some generalized retcode convention some day, we might save
> negative return values for standard libc errno values such
> as -ENOENT and use positive values for or own specific ones).
>
> (We can change the numeric values later of course).
>
> Cheers,
> Martin
>
> > void dm_init(int verbosity);
> > int dm_prereq(unsigned int *v);
> > void skip_libmp_dm_init(void);
> > diff --git a/libmultipath/structs_vec.c b/libmultipath/structs_vec.c
> > index 077f2e42..2225abeb 100644
> > --- a/libmultipath/structs_vec.c
> > +++ b/libmultipath/structs_vec.c
> > @@ -196,43 +196,47 @@ extract_hwe_from_path(struct multipath * mpp)
> > int
> > update_multipath_table (struct multipath *mpp, vector pathvec, int
> > is_daemon)
> > {
> > + int r = DMP_ERR;
> > char params[PARAMS_SIZE] = {0};
> >
> > if (!mpp)
> > - return 1;
> > + return r;
> >
> > - if (dm_get_map(mpp->alias, &mpp->size, params)) {
> > - condlog(3, "%s: cannot get map", mpp->alias);
> > - return 1;
> > + r = dm_get_map(mpp->alias, &mpp->size, params);
> > + if (r != DMP_PASS) {
> > + condlog(3, "%s: %s", mpp->alias, (r == DMP_ERR)? "error
> > getting table" : "map not present");
> > + return r;
> > }
> >
> > if (disassemble_map(pathvec, params, mpp, is_daemon)) {
> > condlog(3, "%s: cannot disassemble map", mpp->alias);
> > - return 1;
> > + return DMP_ERR;
> > }
> >
> > - return 0;
> > + return DMP_PASS;
> > }
> >
> > int
> > update_multipath_status (struct multipath *mpp)
> > {
> > + int r = DMP_ERR;
> > char status[PARAMS_SIZE] = {0};
> >
> > if (!mpp)
> > - return 1;
> > + return r;
> >
> > - if (dm_get_status(mpp->alias, status)) {
> > - condlog(3, "%s: cannot get status", mpp->alias);
> > - return 1;
> > + r = dm_get_status(mpp->alias, status);
> > + if (r != DMP_PASS) {
> > + condlog(3, "%s: %s", mpp->alias, (r == DMP_ERR)? "error
> > getting status" : "map not present");
> > + return r;
> > }
> >
> > if (disassemble_status(status, mpp)) {
> > condlog(3, "%s: cannot disassemble status", mpp-
> > >alias);
> > - return 1;
> > + return DMP_ERR;
> > }
> >
> > - return 0;
> > + return DMP_PASS;
> > }
> >
> > void sync_paths(struct multipath *mpp, vector pathvec)
> > @@ -264,10 +268,10 @@ int
> > update_multipath_strings(struct multipath *mpp, vector pathvec, int
> > is_daemon)
> > {
> > struct pathgroup *pgp;
> > - int i;
> > + int i, r = DMP_ERR;
> >
> > if (!mpp)
> > - return 1;
> > + return r;
> >
> > update_mpp_paths(mpp, pathvec);
> > condlog(4, "%s: %s", mpp->alias, __FUNCTION__);
> > @@ -276,18 +280,21 @@ update_multipath_strings(struct multipath *mpp,
> > vector pathvec, int is_daemon)
> > free_pgvec(mpp->pg, KEEP_PATHS);
> > mpp->pg = NULL;
> >
> > - if (update_multipath_table(mpp, pathvec, is_daemon))
> > - return 1;
> > + r = update_multipath_table(mpp, pathvec, is_daemon);
> > + if (r != DMP_PASS)
> > + return r;
> > +
> > sync_paths(mpp, pathvec);
> >
> > - if (update_multipath_status(mpp))
> > - return 1;
> > + r = update_multipath_status(mpp);
> > + if (r != DMP_PASS)
> > + return r;
> >
> > vector_foreach_slot(mpp->pg, pgp, i)
> > if (pgp->paths)
> > path_group_prio_update(pgp);
> >
> > - return 0;
> > + return DMP_PASS;
> > }
> >
> > static void enter_recovery_mode(struct multipath *mpp)
> > diff --git a/multipathd/main.c b/multipathd/main.c
> > index 205ddb32..d73b1b9a 100644
> > --- a/multipathd/main.c
> > +++ b/multipathd/main.c
> > @@ -418,7 +418,7 @@ int __setup_multipath(struct vectors *vecs,
> > struct multipath *mpp,
> > goto out;
> > }
> >
> > - if (update_multipath_strings(mpp, vecs->pathvec, 1)) {
> > + if (update_multipath_strings(mpp, vecs->pathvec, 1) !=
> > DMP_PASS) {
> > condlog(0, "%s: failed to setup multipath", mpp-
> > >alias);
> > goto out;
> > }
> > @@ -557,9 +557,9 @@ add_map_without_path (struct vectors *vecs, const
> > char *alias)
> > mpp->mpe = find_mpe(conf->mptable, mpp->wwid);
> > put_multipath_config(conf);
> >
> > - if (update_multipath_table(mpp, vecs->pathvec, 1))
> > + if (update_multipath_table(mpp, vecs->pathvec, 1) != DMP_PASS)
> > goto out;
> > - if (update_multipath_status(mpp))
> > + if (update_multipath_status(mpp) != DMP_PASS)
> > goto out;
> >
> > if (!vector_alloc_slot(vecs->mpvec))
> > @@ -1350,8 +1350,8 @@ map_discovery (struct vectors * vecs)
> > return 1;
> >
> > vector_foreach_slot (vecs->mpvec, mpp, i)
> > - if (update_multipath_table(mpp, vecs->pathvec, 1) ||
> > - update_multipath_status(mpp)) {
> > + if (update_multipath_table(mpp, vecs->pathvec, 1) !=
> > DMP_PASS ||
> > + update_multipath_status(mpp) != DMP_PASS) {
> > remove_map(mpp, vecs, 1);
> > i--;
> > }
> > @@ -2091,7 +2091,7 @@ check_path (struct vectors * vecs, struct path
> > * pp, unsigned int ticks)
> > /*
> > * Synchronize with kernel state
> > */
> > - if (update_multipath_strings(pp->mpp, vecs->pathvec, 1)) {
> > + if (update_multipath_strings(pp->mpp, vecs->pathvec, 1) !=
> > DMP_PASS) {
> > condlog(1, "%s: Could not synchronize with kernel
> > state",
> > pp->dev);
> > pp->dmstate = PSTATE_UNDEF;
>
> --
> Dr. Martin Wilck <mwilck at suse.com>, Tel. +49 (0)911 74053 2107
> SUSE Software Solutions Germany GmbH
> HRB 36809, AG Nürnberg GF: Felix
> Imendörffer
>
More information about the dm-devel
mailing list