Add osd_reserve() and osd_set_reserved(), which allow M_WAITOK allocation
of an OSD array,
This commit is contained in:
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30a0e024ee
commit
320d842101
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=297422
@ -25,7 +25,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd January 5, 2011
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.Dd March 30, 2016
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.Dt OSD 9
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.Os
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.Sh NAME
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@ -33,6 +33,9 @@
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.Nm osd_register ,
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.Nm osd_deregister ,
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.Nm osd_set ,
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.Nm osd_reserve ,
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.Nm osd_set_reserved ,
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.Nm osd_free_reserved ,
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.Nm osd_get ,
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.Nm osd_del ,
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.Nm osd_call ,
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@ -63,6 +66,22 @@
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.Fa "void *value"
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.Fc
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.Ft void *
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.Fo osd_reserve
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.Fa "u_int slot"
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.Fc
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.Ft int
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.Fo osd_set_reserved
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.Fa "u_int type"
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.Fa "struct osd *osd"
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.Fa "u_int slot"
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.Fa "void *rsv"
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.Fa "void *value"
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.Fc
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.Ft void
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.Fo osd_free_reserved
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.Fa "void *rsv"
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.Fc
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.Ft void *
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.Fo osd_get
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.Fa "u_int type"
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.Fa "struct osd *osd"
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@ -198,6 +217,15 @@ argument points to a data object to associate with
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.Fa osd .
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.Pp
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The
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.Fn osd_set_reserved
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function does the same as
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.Fn osd_set ,
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but with an extra argument
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.Fa rsv
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that is internal-use memory previously allocated via
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.Fn osd_reserve .
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.Pp
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The
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.Fn osd_get
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function returns the data pointer associated with a kernel data structure's
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.Vt struct osd
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@ -324,6 +352,24 @@ will proceed without any
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.Xr realloc 9
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calls.
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.Pp
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It is possible for
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.Fn osd_set
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to fail to allocate this array. To ensure that such allocation succeeds,
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.Fn osd_reserve
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may be called (in a non-blocking context), and it will pre-allocate the
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memory via
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.Xr malloc 9
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with M_WAITOK.
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Then this pre-allocated memory is passed to
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.Fn osd_set_reserved ,
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which will use it if necessary or otherwise discard it.
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The memory may also be explicitly discarded by calling
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.Fn osd_free_reserved .
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As this method always allocates memory whether or not it is ultimately needed,
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it should be used only rarely, such as in the unlikely event that
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.Fn osd_set
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fails.
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.Pp
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The
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.Nm
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API is geared towards slot identifiers storing pointers to the same underlying
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@ -359,15 +405,27 @@ the kernel including most fast paths.
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returns the slot identifier for the newly registered data type.
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.Pp
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.Fn osd_set
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returns zero on success or ENOMEM if the specified type/slot identifier pair
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and
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.Fn osd_set_reserved
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return zero on success or ENOMEM if the specified type/slot identifier pair
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triggered an internal
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.Xr realloc 9
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which failed.
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which failed
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.Fn ( osd_set_reserved
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will always succeed when
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.Fa rsv
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is non-NULL).
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.Pp
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.Fn osd_get
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returns the data pointer for the specified type/slot identifier pair, or NULL if
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the slot has not been initialised yet.
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.Pp
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.Fn osd_reserve
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returns a pointer suitable for passing to
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.Fn osd_set_reserved
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or
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.Fn osd_free_reserved .
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.Pp
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.Fn osd_call
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returns zero if no method is run or the method for each slot runs successfully.
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If a method for a slot returns non-zero,
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@ -54,7 +54,7 @@ struct osd_master {
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struct sx osd_module_lock;
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struct rmlock osd_object_lock;
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struct mtx osd_list_lock;
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LIST_HEAD(, osd) osd_list; /* (m) */
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LIST_HEAD(, osd) osd_list; /* (l) */
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osd_destructor_t *osd_destructors; /* (o) */
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osd_method_t *osd_methods; /* (m) */
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u_int osd_ntslots; /* (m) */
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@ -197,6 +197,24 @@ osd_deregister(u_int type, u_int slot)
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int
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osd_set(u_int type, struct osd *osd, u_int slot, void *value)
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{
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return (osd_set_reserved(type, osd, slot, NULL, value));
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}
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void *
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osd_reserve(u_int slot)
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{
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KASSERT(slot > 0, ("Invalid slot."));
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OSD_DEBUG("Reserving slot array (slot=%u).", slot);
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return (malloc(sizeof(void *) * slot, M_OSD, M_WAITOK | M_ZERO));
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}
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int
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osd_set_reserved(u_int type, struct osd *osd, u_int slot, void *rsv,
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void *value)
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{
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struct rm_priotracker tracker;
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@ -206,36 +224,34 @@ osd_set(u_int type, struct osd *osd, u_int slot, void *value)
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rm_rlock(&osdm[type].osd_object_lock, &tracker);
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if (slot > osd->osd_nslots) {
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void *newptr;
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if (value == NULL) {
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OSD_DEBUG(
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"Not allocating null slot (type=%u, slot=%u).",
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type, slot);
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rm_runlock(&osdm[type].osd_object_lock, &tracker);
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if (rsv)
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osd_free_reserved(rsv);
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return (0);
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} else if (osd->osd_nslots == 0) {
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/*
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* First OSD for this object, so we need to allocate
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* space and put it onto the list.
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*/
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osd->osd_slots = malloc(sizeof(void *) * slot, M_OSD,
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M_NOWAIT | M_ZERO);
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if (osd->osd_slots == NULL) {
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rm_runlock(&osdm[type].osd_object_lock,
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&tracker);
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return (ENOMEM);
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}
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osd->osd_nslots = slot;
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mtx_lock(&osdm[type].osd_list_lock);
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LIST_INSERT_HEAD(&osdm[type].osd_list, osd, osd_next);
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mtx_unlock(&osdm[type].osd_list_lock);
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OSD_DEBUG("Setting first slot (type=%u).", type);
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} else {
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void *newptr;
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}
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/*
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* Too few slots allocated here, so we need to extend or create
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* the array.
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*/
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if (rsv) {
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/*
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* Too few slots allocated here, needs to extend
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* the array.
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* Use the reserve passed in (assumed to be
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* the right size).
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*/
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newptr = rsv;
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if (osd->osd_nslots != 0) {
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memcpy(newptr, osd->osd_slots,
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sizeof(void *) * osd->osd_nslots);
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free(osd->osd_slots, M_OSD);
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}
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} else {
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newptr = realloc(osd->osd_slots, sizeof(void *) * slot,
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M_OSD, M_NOWAIT | M_ZERO);
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if (newptr == NULL) {
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@ -243,11 +259,22 @@ osd_set(u_int type, struct osd *osd, u_int slot, void *value)
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&tracker);
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return (ENOMEM);
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}
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osd->osd_slots = newptr;
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osd->osd_nslots = slot;
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OSD_DEBUG("Growing slots array (type=%u).", type);
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}
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}
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if (osd->osd_nslots == 0) {
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/*
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* First OSD for this object, so we need to put it
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* onto the list.
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*/
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mtx_lock(&osdm[type].osd_list_lock);
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LIST_INSERT_HEAD(&osdm[type].osd_list, osd, osd_next);
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mtx_unlock(&osdm[type].osd_list_lock);
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OSD_DEBUG("Setting first slot (type=%u).", type);
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} else
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OSD_DEBUG("Growing slots array (type=%u).", type);
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osd->osd_slots = newptr;
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osd->osd_nslots = slot;
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} else if (rsv)
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osd_free_reserved(rsv);
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OSD_DEBUG("Setting slot value (type=%u, slot=%u, value=%p).", type,
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slot, value);
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osd->osd_slots[slot - 1] = value;
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@ -255,6 +282,14 @@ osd_set(u_int type, struct osd *osd, u_int slot, void *value)
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return (0);
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}
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void
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osd_free_reserved(void *rsv)
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{
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OSD_DEBUG("Discarding reserved slot array.");
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free(rsv, M_OSD);
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}
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void *
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osd_get(u_int type, struct osd *osd, u_int slot)
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{
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@ -59,6 +59,10 @@ int osd_register(u_int type, osd_destructor_t destructor,
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void osd_deregister(u_int type, u_int slot);
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int osd_set(u_int type, struct osd *osd, u_int slot, void *value);
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void *osd_reserve(u_int slot);
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int osd_set_reserved(u_int type, struct osd *osd, u_int slot, void *rsv,
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void *value);
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void osd_free_reserved(void *rsv);
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void *osd_get(u_int type, struct osd *osd, u_int slot);
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void osd_del(u_int type, struct osd *osd, u_int slot);
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int osd_call(u_int type, u_int method, void *obj, void *data);
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@ -71,6 +75,8 @@ void osd_exit(u_int type, struct osd *osd);
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osd_deregister(OSD_THREAD, (slot))
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#define osd_thread_set(td, slot, value) \
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osd_set(OSD_THREAD, &(td)->td_osd, (slot), (value))
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#define osd_thread_set_reserved(td, slot, rsv, value) \
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osd_set_reserved(OSD_THREAD, &(td)->td_osd, (slot), (rsv), (value))
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#define osd_thread_get(td, slot) \
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osd_get(OSD_THREAD, &(td)->td_osd, (slot))
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#define osd_thread_del(td, slot) do { \
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@ -88,6 +94,8 @@ void osd_exit(u_int type, struct osd *osd);
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osd_deregister(OSD_JAIL, (slot))
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#define osd_jail_set(pr, slot, value) \
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osd_set(OSD_JAIL, &(pr)->pr_osd, (slot), (value))
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#define osd_jail_set_reserved(pr, slot, rsv, value) \
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osd_set_reserved(OSD_JAIL, &(pr)->pr_osd, (slot), (rsv), (value))
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#define osd_jail_get(pr, slot) \
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osd_get(OSD_JAIL, &(pr)->pr_osd, (slot))
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#define osd_jail_del(pr, slot) \
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