diff options
author | Dan Magenheimer <dan.magenheimer@oracle.com> | 2012-09-05 20:45:00 (GMT) |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-09-06 00:04:37 (GMT) |
commit | faca2ef77abf1983e87d36b14bc181efb983979a (patch) | |
tree | d1eb19f0f247d3c96cca028d2a1cfded7e829724 /drivers/staging/ramster/tmem.c | |
parent | c857ce1659b058c087bce9874cb4eeb5adbf04c5 (diff) | |
download | linux-fsl-qoriq-faca2ef77abf1983e87d36b14bc181efb983979a.tar.xz |
staging: ramster: move to new zcache2 codebase
[V2: rebased to apply to 20120905 staging-next, no other changes]
The original zcache in staging is a "demo" version, and this is a massive
rewrite. This was intended to result in a merged zcache and ramster, but
that option has been blocked so, to continue forward progress on ramster
and future related projects, only ramster moves to the new codebase.
To differentiate between the old demo zcache and the rewrite, we refer
to the latter as zcache2, config'd as CONFIG_ZCACHE2. Zcache and zcache2
cannot be built in the same kernel, so CONFIG_ZCACHE2 implies !CONFIG_ZCACHE.
This developer still has hope that zcache and zcache2 will be merged
into one codebase. Until then, zcache2 can be considered a one-node
version of ramster.
No history of changes was recorded during the zcache2 rewrite and recreating
a sane one would be a Sisyphean task but, since ramster is still in
staging and has been unchanged since it was merged, presumably this
is acceptable.
This commit also provides the hooks in zcache2 for ramster, but all
ramster-specific code is provided in a separate commit.
Some of the highlights of this rewritten codebase for zcache2:
(Note: If you are not familiar with the tmem terminology, you can review
it here: http://lwn.net/Articles/454795/ )
1. Merge of "demo" zcache and the v1.1 version of zcache in ramster. Zcache
and ramster had a great deal of duplicate code which is now merged.
In essence, zcache2 *is* ramster but with no remote machine available,
but !CONFIG_RAMSTER will avoid compiling lots of ramster-specific code.
2. Allocator. Previously, persistent pools used zsmalloc and ephemeral pools
used zbud. Now a completely rewritten zbud is used for both. Notably
this zbud maintains all persistent (frontswap) and ephemeral (cleancache)
pageframes in separate queues in LRU order.
3. Interaction with page allocator. Zbud does no page allocation/freeing,
it is done entirely in zcache2 where it can be tracked more effectively.
4. Better pre-allocation. Previously, on put, if a new pageframe could not be
pre-allocated, the put would fail, even if the allocator had plenty of
partial pages where the data could be stored; this is now fixed.
5. Ouroboros ("eating its own tail") allocation. If no pageframe can be
allocated AND no partial pages are available, the least-recently-used
ephemeral pageframe is reclaimed immediately (including flushing tmem
pointers to it) and re-used. This ensures that most-recently-used
cleancache pages are more likely to be retained than LRU pages and also
that, as in the core mm subsystem, anonymous pages have a higher priority
than clean page cache pages.
6. Zcache and zbud now use debugfs instead of sysfs. Ramster uses debugfs
where possible and sysfs where necessary. (Some ramster configuration
is done from userspace so some sysfs is necessary.)
7. Modularization. As some have observed, the monolithic zcache-main.c code
included zbud code, which has now been separated into its own code module.
Much ramster-specific code in the old ramster zcache-main.c has also been
moved into ramster.c so that it does not get compiled with !CONFIG_RAMSTER.
8. Rebased to 3.5.
This new codebase also provides hooks for several future new features:
A. WasActive patch, requires some mm/frontswap changes previously posted.
A new version of this patch will be provided separately.
See ifdef __PG_WAS_ACTIVE
B. Exclusive gets. It seems tmem _can_ support exclusive gets with a
minor change to both zcache2 and a small backwards-compatible change
to frontswap.c. Explanation and frontswap patch will be provided
separately. See ifdef FRONTSWAP_HAS_EXCLUSIVE_GETS
C. Ouroboros writeback. Since persistent (frontswap) pages may now also be
reclaimed in LRU order, the foundation is in place to properly writeback
these pages back into the swap cache and then the swap disk. This is still
under development and requires some other mm changes which are prototyped.
See ifdef FRONTSWAP_HAS_UNUSE.
A new feature that desperately needs attention (if someone is looking for
a way to contribute) is kernel module support. A preliminary version of
a patch was posted by Erlangen University and needs to be integrated and
tested for zcache2 and brought up to kernel standards.
If anybody is interested on helping out with any of these, let me know!
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/ramster/tmem.c')
-rw-r--r-- | drivers/staging/ramster/tmem.c | 894 |
1 files changed, 894 insertions, 0 deletions
diff --git a/drivers/staging/ramster/tmem.c b/drivers/staging/ramster/tmem.c new file mode 100644 index 0000000..a2b7e03 --- /dev/null +++ b/drivers/staging/ramster/tmem.c @@ -0,0 +1,894 @@ +/* + * In-kernel transcendent memory (generic implementation) + * + * Copyright (c) 2009-2012, Dan Magenheimer, Oracle Corp. + * + * The primary purpose of Transcedent Memory ("tmem") is to map object-oriented + * "handles" (triples containing a pool id, and object id, and an index), to + * pages in a page-accessible memory (PAM). Tmem references the PAM pages via + * an abstract "pampd" (PAM page-descriptor), which can be operated on by a + * set of functions (pamops). Each pampd contains some representation of + * PAGE_SIZE bytes worth of data. For those familiar with key-value stores, + * the tmem handle is a three-level hierarchical key, and the value is always + * reconstituted (but not necessarily stored) as PAGE_SIZE bytes and is + * referenced in the datastore by the pampd. The hierarchy is required + * to ensure that certain invalidation functions can be performed efficiently + * (i.e. flush all indexes associated with this object_id, or + * flush all objects associated with this pool). + * + * Tmem must support potentially millions of pages and must be able to insert, + * find, and delete these pages at a potential frequency of thousands per + * second concurrently across many CPUs, (and, if used with KVM, across many + * vcpus across many guests). Tmem is tracked with a hierarchy of data + * structures, organized by the elements in the handle-tuple: pool_id, + * object_id, and page index. One or more "clients" (e.g. guests) each + * provide one or more tmem_pools. Each pool, contains a hash table of + * rb_trees of tmem_objs. Each tmem_obj contains a radix-tree-like tree + * of pointers, with intermediate nodes called tmem_objnodes. Each leaf + * pointer in this tree points to a pampd, which is accessible only through + * a small set of callbacks registered by the PAM implementation (see + * tmem_register_pamops). Tmem only needs to memory allocation for objs + * and objnodes and this is done via a set of callbacks that must be + * registered by the tmem host implementation (e.g. see tmem_register_hostops). + */ + +#include <linux/list.h> +#include <linux/spinlock.h> +#include <linux/atomic.h> +#ifdef CONFIG_RAMSTER +#include <linux/delay.h> +#endif + +#include "tmem.h" + +/* data structure sentinels used for debugging... see tmem.h */ +#define POOL_SENTINEL 0x87658765 +#define OBJ_SENTINEL 0x12345678 +#define OBJNODE_SENTINEL 0xfedcba09 + +/* + * A tmem host implementation must use this function to register callbacks + * for memory allocation. + */ +static struct tmem_hostops tmem_hostops; + +static void tmem_objnode_tree_init(void); + +void tmem_register_hostops(struct tmem_hostops *m) +{ + tmem_objnode_tree_init(); + tmem_hostops = *m; +} + +/* + * A tmem host implementation must use this function to register + * callbacks for a page-accessible memory (PAM) implementation. + */ +static struct tmem_pamops tmem_pamops; + +void tmem_register_pamops(struct tmem_pamops *m) +{ + tmem_pamops = *m; +} + +/* + * Oid's are potentially very sparse and tmem_objs may have an indeterminately + * short life, being added and deleted at a relatively high frequency. + * So an rb_tree is an ideal data structure to manage tmem_objs. But because + * of the potentially huge number of tmem_objs, each pool manages a hashtable + * of rb_trees to reduce search, insert, delete, and rebalancing time. + * Each hashbucket also has a lock to manage concurrent access and no + * searches, inserts, or deletions can be performed unless the lock is held. + * As a result, care must be taken to ensure tmem routines are not called + * recursively; the vast majority of the time, a recursive call may work + * but a deadlock will occur a small fraction of the time due to the + * hashbucket lock. + * + * The following routines manage tmem_objs. In all of these routines, + * the hashbucket lock is already held. + */ + +/* Search for object==oid in pool, returns object if found. */ +static struct tmem_obj *__tmem_obj_find(struct tmem_hashbucket *hb, + struct tmem_oid *oidp, + struct rb_node **parent, + struct rb_node ***link) +{ + struct rb_node *_parent = NULL, **rbnode; + struct tmem_obj *obj = NULL; + + rbnode = &hb->obj_rb_root.rb_node; + while (*rbnode) { + BUG_ON(RB_EMPTY_NODE(*rbnode)); + _parent = *rbnode; + obj = rb_entry(*rbnode, struct tmem_obj, + rb_tree_node); + switch (tmem_oid_compare(oidp, &obj->oid)) { + case 0: /* equal */ + goto out; + case -1: + rbnode = &(*rbnode)->rb_left; + break; + case 1: + rbnode = &(*rbnode)->rb_right; + break; + } + } + + if (parent) + *parent = _parent; + if (link) + *link = rbnode; + obj = NULL; +out: + return obj; +} + +static struct tmem_obj *tmem_obj_find(struct tmem_hashbucket *hb, + struct tmem_oid *oidp) +{ + return __tmem_obj_find(hb, oidp, NULL, NULL); +} + +static void tmem_pampd_destroy_all_in_obj(struct tmem_obj *, bool); + +/* Free an object that has no more pampds in it. */ +static void tmem_obj_free(struct tmem_obj *obj, struct tmem_hashbucket *hb) +{ + struct tmem_pool *pool; + + BUG_ON(obj == NULL); + ASSERT_SENTINEL(obj, OBJ); + BUG_ON(obj->pampd_count > 0); + pool = obj->pool; + BUG_ON(pool == NULL); + if (obj->objnode_tree_root != NULL) /* may be "stump" with no leaves */ + tmem_pampd_destroy_all_in_obj(obj, false); + BUG_ON(obj->objnode_tree_root != NULL); + BUG_ON((long)obj->objnode_count != 0); + atomic_dec(&pool->obj_count); + BUG_ON(atomic_read(&pool->obj_count) < 0); + INVERT_SENTINEL(obj, OBJ); + obj->pool = NULL; + tmem_oid_set_invalid(&obj->oid); + rb_erase(&obj->rb_tree_node, &hb->obj_rb_root); +} + +/* + * Initialize, and insert an tmem_object_root (called only if find failed). + */ +static void tmem_obj_init(struct tmem_obj *obj, struct tmem_hashbucket *hb, + struct tmem_pool *pool, + struct tmem_oid *oidp) +{ + struct rb_root *root = &hb->obj_rb_root; + struct rb_node **new = NULL, *parent = NULL; + + BUG_ON(pool == NULL); + atomic_inc(&pool->obj_count); + obj->objnode_tree_height = 0; + obj->objnode_tree_root = NULL; + obj->pool = pool; + obj->oid = *oidp; + obj->objnode_count = 0; + obj->pampd_count = 0; +#ifdef CONFIG_RAMSTER + if (tmem_pamops.new_obj != NULL) + (*tmem_pamops.new_obj)(obj); +#endif + SET_SENTINEL(obj, OBJ); + + if (__tmem_obj_find(hb, oidp, &parent, &new)) + BUG(); + + rb_link_node(&obj->rb_tree_node, parent, new); + rb_insert_color(&obj->rb_tree_node, root); +} + +/* + * Tmem is managed as a set of tmem_pools with certain attributes, such as + * "ephemeral" vs "persistent". These attributes apply to all tmem_objs + * and all pampds that belong to a tmem_pool. A tmem_pool is created + * or deleted relatively rarely (for example, when a filesystem is + * mounted or unmounted). + */ + +/* flush all data from a pool and, optionally, free it */ +static void tmem_pool_flush(struct tmem_pool *pool, bool destroy) +{ + struct rb_node *rbnode; + struct tmem_obj *obj; + struct tmem_hashbucket *hb = &pool->hashbucket[0]; + int i; + + BUG_ON(pool == NULL); + for (i = 0; i < TMEM_HASH_BUCKETS; i++, hb++) { + spin_lock(&hb->lock); + rbnode = rb_first(&hb->obj_rb_root); + while (rbnode != NULL) { + obj = rb_entry(rbnode, struct tmem_obj, rb_tree_node); + rbnode = rb_next(rbnode); + tmem_pampd_destroy_all_in_obj(obj, true); + tmem_obj_free(obj, hb); + (*tmem_hostops.obj_free)(obj, pool); + } + spin_unlock(&hb->lock); + } + if (destroy) + list_del(&pool->pool_list); +} + +/* + * A tmem_obj contains a radix-tree-like tree in which the intermediate + * nodes are called tmem_objnodes. (The kernel lib/radix-tree.c implementation + * is very specialized and tuned for specific uses and is not particularly + * suited for use from this code, though some code from the core algorithms has + * been reused, thus the copyright notices below). Each tmem_objnode contains + * a set of pointers which point to either a set of intermediate tmem_objnodes + * or a set of of pampds. + * + * Portions Copyright (C) 2001 Momchil Velikov + * Portions Copyright (C) 2001 Christoph Hellwig + * Portions Copyright (C) 2005 SGI, Christoph Lameter <clameter@sgi.com> + */ + +struct tmem_objnode_tree_path { + struct tmem_objnode *objnode; + int offset; +}; + +/* objnode height_to_maxindex translation */ +static unsigned long tmem_objnode_tree_h2max[OBJNODE_TREE_MAX_PATH + 1]; + +static void tmem_objnode_tree_init(void) +{ + unsigned int ht, tmp; + + for (ht = 0; ht < ARRAY_SIZE(tmem_objnode_tree_h2max); ht++) { + tmp = ht * OBJNODE_TREE_MAP_SHIFT; + if (tmp >= OBJNODE_TREE_INDEX_BITS) + tmem_objnode_tree_h2max[ht] = ~0UL; + else + tmem_objnode_tree_h2max[ht] = + (~0UL >> (OBJNODE_TREE_INDEX_BITS - tmp - 1)) >> 1; + } +} + +static struct tmem_objnode *tmem_objnode_alloc(struct tmem_obj *obj) +{ + struct tmem_objnode *objnode; + + ASSERT_SENTINEL(obj, OBJ); + BUG_ON(obj->pool == NULL); + ASSERT_SENTINEL(obj->pool, POOL); + objnode = (*tmem_hostops.objnode_alloc)(obj->pool); + if (unlikely(objnode == NULL)) + goto out; + objnode->obj = obj; + SET_SENTINEL(objnode, OBJNODE); + memset(&objnode->slots, 0, sizeof(objnode->slots)); + objnode->slots_in_use = 0; + obj->objnode_count++; +out: + return objnode; +} + +static void tmem_objnode_free(struct tmem_objnode *objnode) +{ + struct tmem_pool *pool; + int i; + + BUG_ON(objnode == NULL); + for (i = 0; i < OBJNODE_TREE_MAP_SIZE; i++) + BUG_ON(objnode->slots[i] != NULL); + ASSERT_SENTINEL(objnode, OBJNODE); + INVERT_SENTINEL(objnode, OBJNODE); + BUG_ON(objnode->obj == NULL); + ASSERT_SENTINEL(objnode->obj, OBJ); + pool = objnode->obj->pool; + BUG_ON(pool == NULL); + ASSERT_SENTINEL(pool, POOL); + objnode->obj->objnode_count--; + objnode->obj = NULL; + (*tmem_hostops.objnode_free)(objnode, pool); +} + +/* + * Lookup index in object and return associated pampd (or NULL if not found). + */ +static void **__tmem_pampd_lookup_in_obj(struct tmem_obj *obj, uint32_t index) +{ + unsigned int height, shift; + struct tmem_objnode **slot = NULL; + + BUG_ON(obj == NULL); + ASSERT_SENTINEL(obj, OBJ); + BUG_ON(obj->pool == NULL); + ASSERT_SENTINEL(obj->pool, POOL); + + height = obj->objnode_tree_height; + if (index > tmem_objnode_tree_h2max[obj->objnode_tree_height]) + goto out; + if (height == 0 && obj->objnode_tree_root) { + slot = &obj->objnode_tree_root; + goto out; + } + shift = (height-1) * OBJNODE_TREE_MAP_SHIFT; + slot = &obj->objnode_tree_root; + while (height > 0) { + if (*slot == NULL) + goto out; + slot = (struct tmem_objnode **) + ((*slot)->slots + + ((index >> shift) & OBJNODE_TREE_MAP_MASK)); + shift -= OBJNODE_TREE_MAP_SHIFT; + height--; + } +out: + return slot != NULL ? (void **)slot : NULL; +} + +static void *tmem_pampd_lookup_in_obj(struct tmem_obj *obj, uint32_t index) +{ + struct tmem_objnode **slot; + + slot = (struct tmem_objnode **)__tmem_pampd_lookup_in_obj(obj, index); + return slot != NULL ? *slot : NULL; +} + +#ifdef CONFIG_RAMSTER +static void *tmem_pampd_replace_in_obj(struct tmem_obj *obj, uint32_t index, + void *new_pampd, bool no_free) +{ + struct tmem_objnode **slot; + void *ret = NULL; + + slot = (struct tmem_objnode **)__tmem_pampd_lookup_in_obj(obj, index); + if ((slot != NULL) && (*slot != NULL)) { + void *old_pampd = *(void **)slot; + *(void **)slot = new_pampd; + if (!no_free) + (*tmem_pamops.free)(old_pampd, obj->pool, + NULL, 0, false); + ret = new_pampd; + } + return ret; +} +#endif + +static int tmem_pampd_add_to_obj(struct tmem_obj *obj, uint32_t index, + void *pampd) +{ + int ret = 0; + struct tmem_objnode *objnode = NULL, *newnode, *slot; + unsigned int height, shift; + int offset = 0; + + /* if necessary, extend the tree to be higher */ + if (index > tmem_objnode_tree_h2max[obj->objnode_tree_height]) { + height = obj->objnode_tree_height + 1; + if (index > tmem_objnode_tree_h2max[height]) + while (index > tmem_objnode_tree_h2max[height]) + height++; + if (obj->objnode_tree_root == NULL) { + obj->objnode_tree_height = height; + goto insert; + } + do { + newnode = tmem_objnode_alloc(obj); + if (!newnode) { + ret = -ENOMEM; + goto out; + } + newnode->slots[0] = obj->objnode_tree_root; + newnode->slots_in_use = 1; + obj->objnode_tree_root = newnode; + obj->objnode_tree_height++; + } while (height > obj->objnode_tree_height); + } +insert: + slot = obj->objnode_tree_root; + height = obj->objnode_tree_height; + shift = (height-1) * OBJNODE_TREE_MAP_SHIFT; + while (height > 0) { + if (slot == NULL) { + /* add a child objnode. */ + slot = tmem_objnode_alloc(obj); + if (!slot) { + ret = -ENOMEM; + goto out; + } + if (objnode) { + + objnode->slots[offset] = slot; + objnode->slots_in_use++; + } else + obj->objnode_tree_root = slot; + } + /* go down a level */ + offset = (index >> shift) & OBJNODE_TREE_MAP_MASK; + objnode = slot; + slot = objnode->slots[offset]; + shift -= OBJNODE_TREE_MAP_SHIFT; + height--; + } + BUG_ON(slot != NULL); + if (objnode) { + objnode->slots_in_use++; + objnode->slots[offset] = pampd; + } else + obj->objnode_tree_root = pampd; + obj->pampd_count++; +out: + return ret; +} + +static void *tmem_pampd_delete_from_obj(struct tmem_obj *obj, uint32_t index) +{ + struct tmem_objnode_tree_path path[OBJNODE_TREE_MAX_PATH + 1]; + struct tmem_objnode_tree_path *pathp = path; + struct tmem_objnode *slot = NULL; + unsigned int height, shift; + int offset; + + BUG_ON(obj == NULL); + ASSERT_SENTINEL(obj, OBJ); + BUG_ON(obj->pool == NULL); + ASSERT_SENTINEL(obj->pool, POOL); + height = obj->objnode_tree_height; + if (index > tmem_objnode_tree_h2max[height]) + goto out; + slot = obj->objnode_tree_root; + if (height == 0 && obj->objnode_tree_root) { + obj->objnode_tree_root = NULL; + goto out; + } + shift = (height - 1) * OBJNODE_TREE_MAP_SHIFT; + pathp->objnode = NULL; + do { + if (slot == NULL) + goto out; + pathp++; + offset = (index >> shift) & OBJNODE_TREE_MAP_MASK; + pathp->offset = offset; + pathp->objnode = slot; + slot = slot->slots[offset]; + shift -= OBJNODE_TREE_MAP_SHIFT; + height--; + } while (height > 0); + if (slot == NULL) + goto out; + while (pathp->objnode) { + pathp->objnode->slots[pathp->offset] = NULL; + pathp->objnode->slots_in_use--; + if (pathp->objnode->slots_in_use) { + if (pathp->objnode == obj->objnode_tree_root) { + while (obj->objnode_tree_height > 0 && + obj->objnode_tree_root->slots_in_use == 1 && + obj->objnode_tree_root->slots[0]) { + struct tmem_objnode *to_free = + obj->objnode_tree_root; + + obj->objnode_tree_root = + to_free->slots[0]; + obj->objnode_tree_height--; + to_free->slots[0] = NULL; + to_free->slots_in_use = 0; + tmem_objnode_free(to_free); + } + } + goto out; + } + tmem_objnode_free(pathp->objnode); /* 0 slots used, free it */ + pathp--; + } + obj->objnode_tree_height = 0; + obj->objnode_tree_root = NULL; + +out: + if (slot != NULL) + obj->pampd_count--; + BUG_ON(obj->pampd_count < 0); + return slot; +} + +/* Recursively walk the objnode_tree destroying pampds and objnodes. */ +static void tmem_objnode_node_destroy(struct tmem_obj *obj, + struct tmem_objnode *objnode, + unsigned int ht) +{ + int i; + + if (ht == 0) + return; + for (i = 0; i < OBJNODE_TREE_MAP_SIZE; i++) { + if (objnode->slots[i]) { + if (ht == 1) { + obj->pampd_count--; + (*tmem_pamops.free)(objnode->slots[i], + obj->pool, NULL, 0, true); + objnode->slots[i] = NULL; + continue; + } + tmem_objnode_node_destroy(obj, objnode->slots[i], ht-1); + tmem_objnode_free(objnode->slots[i]); + objnode->slots[i] = NULL; + } + } +} + +static void tmem_pampd_destroy_all_in_obj(struct tmem_obj *obj, + bool pool_destroy) +{ + if (obj->objnode_tree_root == NULL) + return; + if (obj->objnode_tree_height == 0) { + obj->pampd_count--; + (*tmem_pamops.free)(obj->objnode_tree_root, + obj->pool, NULL, 0, true); + } else { + tmem_objnode_node_destroy(obj, obj->objnode_tree_root, + obj->objnode_tree_height); + tmem_objnode_free(obj->objnode_tree_root); + obj->objnode_tree_height = 0; + } + obj->objnode_tree_root = NULL; +#ifdef CONFIG_RAMSTER + if (tmem_pamops.free_obj != NULL) + (*tmem_pamops.free_obj)(obj->pool, obj, pool_destroy); +#endif +} + +/* + * Tmem is operated on by a set of well-defined actions: + * "put", "get", "flush", "flush_object", "new pool" and "destroy pool". + * (The tmem ABI allows for subpages and exchanges but these operations + * are not included in this implementation.) + * + * These "tmem core" operations are implemented in the following functions. + */ + +/* + * "Put" a page, e.g. associate the passed pampd with the passed handle. + * Tmem_put is complicated by a corner case: What if a page with matching + * handle already exists in tmem? To guarantee coherency, one of two + * actions is necessary: Either the data for the page must be overwritten, + * or the page must be "flushed" so that the data is not accessible to a + * subsequent "get". Since these "duplicate puts" are relatively rare, + * this implementation always flushes for simplicity. + */ +int tmem_put(struct tmem_pool *pool, struct tmem_oid *oidp, uint32_t index, + bool raw, void *pampd_to_use) +{ + struct tmem_obj *obj = NULL, *objfound = NULL, *objnew = NULL; + void *pampd = NULL, *pampd_del = NULL; + int ret = -ENOMEM; + struct tmem_hashbucket *hb; + + hb = &pool->hashbucket[tmem_oid_hash(oidp)]; + spin_lock(&hb->lock); + obj = objfound = tmem_obj_find(hb, oidp); + if (obj != NULL) { + pampd = tmem_pampd_lookup_in_obj(objfound, index); + if (pampd != NULL) { + /* if found, is a dup put, flush the old one */ + pampd_del = tmem_pampd_delete_from_obj(obj, index); + BUG_ON(pampd_del != pampd); + (*tmem_pamops.free)(pampd, pool, oidp, index, true); + if (obj->pampd_count == 0) { + objnew = obj; + objfound = NULL; + } + pampd = NULL; + } + } else { + obj = objnew = (*tmem_hostops.obj_alloc)(pool); + if (unlikely(obj == NULL)) { + ret = -ENOMEM; + goto out; + } + tmem_obj_init(obj, hb, pool, oidp); + } + BUG_ON(obj == NULL); + BUG_ON(((objnew != obj) && (objfound != obj)) || (objnew == objfound)); + pampd = pampd_to_use; + BUG_ON(pampd_to_use == NULL); + ret = tmem_pampd_add_to_obj(obj, index, pampd); + if (unlikely(ret == -ENOMEM)) + /* may have partially built objnode tree ("stump") */ + goto delete_and_free; + (*tmem_pamops.create_finish)(pampd, is_ephemeral(pool)); + goto out; + +delete_and_free: + (void)tmem_pampd_delete_from_obj(obj, index); + if (pampd) + (*tmem_pamops.free)(pampd, pool, NULL, 0, true); + if (objnew) { + tmem_obj_free(objnew, hb); + (*tmem_hostops.obj_free)(objnew, pool); + } +out: + spin_unlock(&hb->lock); + return ret; +} + +#ifdef CONFIG_RAMSTER +/* + * For ramster only: The following routines provide a two-step sequence + * to allow the caller to replace a pampd in the tmem data structures with + * another pampd. Here, we lookup the passed handle and, if found, return the + * associated pampd and object, leaving the hashbucket locked and returning + * a reference to it. The caller is expected to immediately call the + * matching tmem_localify_finish routine which will handles the replacement + * and unlocks the hashbucket. + */ +void *tmem_localify_get_pampd(struct tmem_pool *pool, struct tmem_oid *oidp, + uint32_t index, struct tmem_obj **ret_obj, + void **saved_hb) +{ + struct tmem_hashbucket *hb; + struct tmem_obj *obj = NULL; + void *pampd = NULL; + + hb = &pool->hashbucket[tmem_oid_hash(oidp)]; + spin_lock(&hb->lock); + obj = tmem_obj_find(hb, oidp); + if (likely(obj != NULL)) + pampd = tmem_pampd_lookup_in_obj(obj, index); + *ret_obj = obj; + *saved_hb = (void *)hb; + /* note, hashbucket remains locked */ + return pampd; +} + +void tmem_localify_finish(struct tmem_obj *obj, uint32_t index, + void *pampd, void *saved_hb, bool delete) +{ + struct tmem_hashbucket *hb = (struct tmem_hashbucket *)saved_hb; + + BUG_ON(!spin_is_locked(&hb->lock)); + if (pampd != NULL) { + BUG_ON(obj == NULL); + (void)tmem_pampd_replace_in_obj(obj, index, pampd, 1); + (*tmem_pamops.create_finish)(pampd, is_ephemeral(obj->pool)); + } else if (delete) { + BUG_ON(obj == NULL); + (void)tmem_pampd_delete_from_obj(obj, index); + } + spin_unlock(&hb->lock); +} + +/* + * For ramster only. Helper function to support asynchronous tmem_get. + */ +static int tmem_repatriate(void **ppampd, struct tmem_hashbucket *hb, + struct tmem_pool *pool, struct tmem_oid *oidp, + uint32_t index, bool free, char *data) +{ + void *old_pampd = *ppampd, *new_pampd = NULL; + bool intransit = false; + int ret = 0; + + if (!is_ephemeral(pool)) + new_pampd = (*tmem_pamops.repatriate_preload)( + old_pampd, pool, oidp, index, &intransit); + if (intransit) + ret = -EAGAIN; + else if (new_pampd != NULL) + *ppampd = new_pampd; + /* must release the hb->lock else repatriate can't sleep */ + spin_unlock(&hb->lock); + if (!intransit) + ret = (*tmem_pamops.repatriate)(old_pampd, new_pampd, pool, + oidp, index, free, data); + if (ret == -EAGAIN) { + /* rare I think, but should cond_resched()??? */ + usleep_range(10, 1000); + } else if (ret == -ENOTCONN || ret == -EHOSTDOWN) { + ret = -1; + } else if (ret != 0 && ret != -ENOENT) { + ret = -1; + } + /* note hb->lock has now been unlocked */ + return ret; +} + +/* + * For ramster only. If a page in tmem matches the handle, replace the + * page so that any subsequent "get" gets the new page. Returns 0 if + * there was a page to replace, else returns -1. + */ +int tmem_replace(struct tmem_pool *pool, struct tmem_oid *oidp, + uint32_t index, void *new_pampd) +{ + struct tmem_obj *obj; + int ret = -1; + struct tmem_hashbucket *hb; + + hb = &pool->hashbucket[tmem_oid_hash(oidp)]; + spin_lock(&hb->lock); + obj = tmem_obj_find(hb, oidp); + if (obj == NULL) + goto out; + new_pampd = tmem_pampd_replace_in_obj(obj, index, new_pampd, 0); + /* if we bug here, pamops wasn't properly set up for ramster */ + BUG_ON(tmem_pamops.replace_in_obj == NULL); + ret = (*tmem_pamops.replace_in_obj)(new_pampd, obj); +out: + spin_unlock(&hb->lock); + return ret; +} +#endif + +/* + * "Get" a page, e.g. if a pampd can be found matching the passed handle, + * use a pamops callback to recreated the page from the pampd with the + * matching handle. By tmem definition, when a "get" is successful on + * an ephemeral page, the page is "flushed", and when a "get" is successful + * on a persistent page, the page is retained in tmem. Note that to preserve + * coherency, "get" can never be skipped if tmem contains the data. + * That is, if a get is done with a certain handle and fails, any + * subsequent "get" must also fail (unless of course there is a + * "put" done with the same handle). + */ +int tmem_get(struct tmem_pool *pool, struct tmem_oid *oidp, uint32_t index, + char *data, size_t *sizep, bool raw, int get_and_free) +{ + struct tmem_obj *obj; + void *pampd = NULL; + bool ephemeral = is_ephemeral(pool); + int ret = -1; + struct tmem_hashbucket *hb; + bool free = (get_and_free == 1) || ((get_and_free == 0) && ephemeral); + bool lock_held = false; + void **ppampd; + + do { + hb = &pool->hashbucket[tmem_oid_hash(oidp)]; + spin_lock(&hb->lock); + lock_held = true; + obj = tmem_obj_find(hb, oidp); + if (obj == NULL) + goto out; + ppampd = __tmem_pampd_lookup_in_obj(obj, index); + if (ppampd == NULL) + goto out; +#ifdef CONFIG_RAMSTER + if ((tmem_pamops.is_remote != NULL) && + tmem_pamops.is_remote(*ppampd)) { + ret = tmem_repatriate(ppampd, hb, pool, oidp, + index, free, data); + /* tmem_repatriate releases hb->lock */ + lock_held = false; + *sizep = PAGE_SIZE; + if (ret != -EAGAIN) + goto out; + } +#endif + } while (ret == -EAGAIN); + if (free) + pampd = tmem_pampd_delete_from_obj(obj, index); + else + pampd = tmem_pampd_lookup_in_obj(obj, index); + if (pampd == NULL) + goto out; + if (free) { + if (obj->pampd_count == 0) { + tmem_obj_free(obj, hb); + (*tmem_hostops.obj_free)(obj, pool); + obj = NULL; + } + } + if (free) + ret = (*tmem_pamops.get_data_and_free)( + data, sizep, raw, pampd, pool, oidp, index); + else + ret = (*tmem_pamops.get_data)( + data, sizep, raw, pampd, pool, oidp, index); + if (ret < 0) + goto out; + ret = 0; +out: + if (lock_held) + spin_unlock(&hb->lock); + return ret; +} + +/* + * If a page in tmem matches the handle, "flush" this page from tmem such + * that any subsequent "get" does not succeed (unless, of course, there + * was another "put" with the same handle). + */ +int tmem_flush_page(struct tmem_pool *pool, + struct tmem_oid *oidp, uint32_t index) +{ + struct tmem_obj *obj; + void *pampd; + int ret = -1; + struct tmem_hashbucket *hb; + + hb = &pool->hashbucket[tmem_oid_hash(oidp)]; + spin_lock(&hb->lock); + obj = tmem_obj_find(hb, oidp); + if (obj == NULL) + goto out; + pampd = tmem_pampd_delete_from_obj(obj, index); + if (pampd == NULL) + goto out; + (*tmem_pamops.free)(pampd, pool, oidp, index, true); + if (obj->pampd_count == 0) { + tmem_obj_free(obj, hb); + (*tmem_hostops.obj_free)(obj, pool); + } + ret = 0; + +out: + spin_unlock(&hb->lock); + return ret; +} + +/* + * "Flush" all pages in tmem matching this oid. + */ +int tmem_flush_object(struct tmem_pool *pool, struct tmem_oid *oidp) +{ + struct tmem_obj *obj; + struct tmem_hashbucket *hb; + int ret = -1; + + hb = &pool->hashbucket[tmem_oid_hash(oidp)]; + spin_lock(&hb->lock); + obj = tmem_obj_find(hb, oidp); + if (obj == NULL) + goto out; + tmem_pampd_destroy_all_in_obj(obj, false); + tmem_obj_free(obj, hb); + (*tmem_hostops.obj_free)(obj, pool); + ret = 0; + +out: + spin_unlock(&hb->lock); + return ret; +} + +/* + * "Flush" all pages (and tmem_objs) from this tmem_pool and disable + * all subsequent access to this tmem_pool. + */ +int tmem_destroy_pool(struct tmem_pool *pool) +{ + int ret = -1; + + if (pool == NULL) + goto out; + tmem_pool_flush(pool, 1); + ret = 0; +out: + return ret; +} + +static LIST_HEAD(tmem_global_pool_list); + +/* + * Create a new tmem_pool with the provided flag and return + * a pool id provided by the tmem host implementation. + */ +void tmem_new_pool(struct tmem_pool *pool, uint32_t flags) +{ + int persistent = flags & TMEM_POOL_PERSIST; + int shared = flags & TMEM_POOL_SHARED; + struct tmem_hashbucket *hb = &pool->hashbucket[0]; + int i; + + for (i = 0; i < TMEM_HASH_BUCKETS; i++, hb++) { + hb->obj_rb_root = RB_ROOT; + spin_lock_init(&hb->lock); + } + INIT_LIST_HEAD(&pool->pool_list); + atomic_set(&pool->obj_count, 0); + SET_SENTINEL(pool, POOL); + list_add_tail(&pool->pool_list, &tmem_global_pool_list); + pool->persistent = persistent; + pool->shared = shared; +} |