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38 #ifndef _LUSTRE_CL_OBJECT_H
39 #define _LUSTRE_CL_OBJECT_H
41 /** \defgroup clio clio
43 * Client objects implement io operations and cache pages.
45 * Examples: lov and osc are implementations of cl interface.
47 * Big Theory Statement.
51 * Client implementation is based on the following data-types:
57 * - cl_lock represents an extent lock on an object.
59 * - cl_io represents high-level i/o activity such as whole read/write
60 * system call, or write-out of pages from under the lock being
61 * canceled. cl_io has sub-ios that can be stopped and resumed
62 * independently, thus achieving high degree of transfer
63 * parallelism. Single cl_io can be advanced forward by
64 * the multiple threads (although in the most usual case of
65 * read/write system call it is associated with the single user
66 * thread, that issued the system call).
68 * - cl_req represents a collection of pages for a transfer. cl_req is
69 * constructed by req-forming engine that tries to saturate
70 * transport with large and continuous transfers.
74 * - to avoid confusion high-level I/O operation like read or write system
75 * call is referred to as "an io", whereas low-level I/O operation, like
76 * RPC, is referred to as "a transfer"
78 * - "generic code" means generic (not file system specific) code in the
79 * hosting environment. "cl-code" means code (mostly in cl_*.c files) that
80 * is not layer specific.
86 * - cl_object_header::coh_page_guard
87 * - cl_object_header::coh_lock_guard
90 * See the top comment in cl_object.c for the description of overall locking and
91 * reference-counting design.
93 * See comments below for the description of i/o, page, and dlm-locking
100 * super-class definitions.
102 #include <lu_object.h>
105 # include <linux/mutex.h>
106 # include <linux/radix-tree.h>
112 struct cl_device_operations;
115 struct cl_object_page_operations;
116 struct cl_object_lock_operations;
119 struct cl_page_slice;
121 struct cl_lock_slice;
123 struct cl_lock_operations;
124 struct cl_page_operations;
133 * Operations for each data device in the client stack.
135 * \see vvp_cl_ops, lov_cl_ops, lovsub_cl_ops, osc_cl_ops
137 struct cl_device_operations {
139 * Initialize cl_req. This method is called top-to-bottom on all
140 * devices in the stack to get them a chance to allocate layer-private
141 * data, and to attach them to the cl_req by calling
142 * cl_req_slice_add().
144 * \see osc_req_init(), lov_req_init(), lovsub_req_init()
145 * \see ccc_req_init()
147 int (*cdo_req_init)(const struct lu_env *env, struct cl_device *dev,
152 * Device in the client stack.
154 * \see ccc_device, lov_device, lovsub_device, osc_device
158 struct lu_device cd_lu_dev;
159 /** Per-layer operation vector. */
160 const struct cl_device_operations *cd_ops;
163 /** \addtogroup cl_object cl_object
166 * "Data attributes" of cl_object. Data attributes can be updated
167 * independently for a sub-object, and top-object's attributes are calculated
168 * from sub-objects' ones.
171 /** Object size, in bytes */
174 * Known minimal size, in bytes.
176 * This is only valid when at least one DLM lock is held.
179 /** Modification time. Measured in seconds since epoch. */
181 /** Access time. Measured in seconds since epoch. */
183 /** Change time. Measured in seconds since epoch. */
186 * Blocks allocated to this cl_object on the server file system.
188 * \todo XXX An interface for block size is needed.
192 * User identifier for quota purposes.
196 * Group identifier for quota purposes.
202 * Fields in cl_attr that are being set.
216 * Sub-class of lu_object with methods common for objects on the client
219 * cl_object: represents a regular file system object, both a file and a
220 * stripe. cl_object is based on lu_object: it is identified by a fid,
221 * layered, cached, hashed, and lrued. Important distinction with the server
222 * side, where md_object and dt_object are used, is that cl_object "fans out"
223 * at the lov/sns level: depending on the file layout, single file is
224 * represented as a set of "sub-objects" (stripes). At the implementation
225 * level, struct lov_object contains an array of cl_objects. Each sub-object
226 * is a full-fledged cl_object, having its fid, living in the lru and hash
229 * This leads to the next important difference with the server side: on the
230 * client, it's quite usual to have objects with the different sequence of
231 * layers. For example, typical top-object is composed of the following
237 * whereas its sub-objects are composed of
242 * layers. Here "lovsub" is a mostly dummy layer, whose purpose is to keep
243 * track of the object-subobject relationship.
245 * Sub-objects are not cached independently: when top-object is about to
246 * be discarded from the memory, all its sub-objects are torn-down and
249 * \see ccc_object, lov_object, lovsub_object, osc_object
253 struct lu_object co_lu;
254 /** per-object-layer operations */
255 const struct cl_object_operations *co_ops;
259 * Description of the client object configuration. This is used for the
260 * creation of a new client object that is identified by a more state than
263 struct cl_object_conf {
265 struct lu_object_conf coc_lu;
268 * Object layout. This is consumed by lov.
270 struct lustre_md *coc_md;
272 * Description of particular stripe location in the
273 * cluster. This is consumed by osc.
275 struct lov_oinfo *coc_oinfo;
278 * VFS inode. This is consumed by vvp.
280 struct inode *coc_inode;
284 * Operations implemented for each cl object layer.
286 * \see vvp_ops, lov_ops, lovsub_ops, osc_ops
288 struct cl_object_operations {
290 * Initialize page slice for this layer. Called top-to-bottom through
291 * every object layer when a new cl_page is instantiated. Layer
292 * keeping private per-page data, or requiring its own page operations
293 * vector should allocate these data here, and attach then to the page
294 * by calling cl_page_slice_add(). \a vmpage is locked (in the VM
297 * \retval NULL success.
299 * \retval ERR_PTR(errno) failure code.
301 * \retval valid-pointer pointer to already existing referenced page
302 * to be used instead of newly created.
304 struct cl_page *(*coo_page_init)(const struct lu_env *env,
305 struct cl_object *obj,
306 struct cl_page *page,
309 * Initialize lock slice for this layer. Called top-to-bottom through
310 * every object layer when a new cl_lock is instantiated. Layer
311 * keeping private per-lock data, or requiring its own lock operations
312 * vector should allocate these data here, and attach then to the lock
313 * by calling cl_lock_slice_add(). Mandatory.
315 int (*coo_lock_init)(const struct lu_env *env,
316 struct cl_object *obj, struct cl_lock *lock,
317 const struct cl_io *io);
319 * Initialize io state for a given layer.
321 * called top-to-bottom once per io existence to initialize io
322 * state. If layer wants to keep some state for this type of io, it
323 * has to embed struct cl_io_slice in lu_env::le_ses, and register
324 * slice with cl_io_slice_add(). It is guaranteed that all threads
325 * participating in this io share the same session.
327 int (*coo_io_init)(const struct lu_env *env,
328 struct cl_object *obj, struct cl_io *io);
330 * Fill portion of \a attr that this layer controls. This method is
331 * called top-to-bottom through all object layers.
333 * \pre cl_object_header::coh_attr_guard of the top-object is locked.
335 * \return 0: to continue
336 * \return +ve: to stop iterating through layers (but 0 is returned
337 * from enclosing cl_object_attr_get())
338 * \return -ve: to signal error
340 int (*coo_attr_get)(const struct lu_env *env, struct cl_object *obj,
341 struct cl_attr *attr);
345 * \a valid is a bitmask composed from enum #cl_attr_valid, and
346 * indicating what attributes are to be set.
348 * \pre cl_object_header::coh_attr_guard of the top-object is locked.
350 * \return the same convention as for
351 * cl_object_operations::coo_attr_get() is used.
353 int (*coo_attr_set)(const struct lu_env *env, struct cl_object *obj,
354 const struct cl_attr *attr, unsigned valid);
356 * Update object configuration. Called top-to-bottom to modify object
359 * XXX error conditions and handling.
361 int (*coo_conf_set)(const struct lu_env *env, struct cl_object *obj,
362 const struct cl_object_conf *conf);
364 * Glimpse ast. Executed when glimpse ast arrives for a lock on this
365 * object. Layers are supposed to fill parts of \a lvb that will be
366 * shipped to the glimpse originator as a glimpse result.
368 * \see ccc_object_glimpse(), lovsub_object_glimpse(),
369 * \see osc_object_glimpse()
371 int (*coo_glimpse)(const struct lu_env *env,
372 const struct cl_object *obj, struct ost_lvb *lvb);
376 * Extended header for client object.
378 struct cl_object_header {
379 /** Standard lu_object_header. cl_object::co_lu::lo_header points
381 struct lu_object_header coh_lu;
383 * \todo XXX move locks below to the separate cache-lines, they are
384 * mostly useless otherwise.
387 /** Lock protecting page tree. */
388 cfs_spinlock_t coh_page_guard;
389 /** Lock protecting lock list. */
390 cfs_spinlock_t coh_lock_guard;
392 /** Radix tree of cl_page's, cached for this object. */
393 struct radix_tree_root coh_tree;
394 /** # of pages in radix tree. */
395 unsigned long coh_pages;
396 /** List of cl_lock's granted for this object. */
397 cfs_list_t coh_locks;
400 * Parent object. It is assumed that an object has a well-defined
401 * parent, but not a well-defined child (there may be multiple
402 * sub-objects, for the same top-object). cl_object_header::coh_parent
403 * field allows certain code to be written generically, without
404 * limiting possible cl_object layouts unduly.
406 struct cl_object_header *coh_parent;
408 * Protects consistency between cl_attr of parent object and
409 * attributes of sub-objects, that the former is calculated ("merged")
412 * \todo XXX this can be read/write lock if needed.
414 cfs_spinlock_t coh_attr_guard;
416 * Number of objects above this one: 0 for a top-object, 1 for its
419 unsigned coh_nesting;
423 * Helper macro: iterate over all layers of the object \a obj, assigning every
424 * layer top-to-bottom to \a slice.
426 #define cl_object_for_each(slice, obj) \
427 cfs_list_for_each_entry((slice), \
428 &(obj)->co_lu.lo_header->loh_layers, \
431 * Helper macro: iterate over all layers of the object \a obj, assigning every
432 * layer bottom-to-top to \a slice.
434 #define cl_object_for_each_reverse(slice, obj) \
435 cfs_list_for_each_entry_reverse((slice), \
436 &(obj)->co_lu.lo_header->loh_layers, \
441 #define pgoff_t unsigned long
444 #define CL_PAGE_EOF ((pgoff_t)~0ull)
446 /** \addtogroup cl_page cl_page
450 * Layered client page.
452 * cl_page: represents a portion of a file, cached in the memory. All pages
453 * of the given file are of the same size, and are kept in the radix tree
454 * hanging off the cl_object. cl_page doesn't fan out, but as sub-objects
455 * of the top-level file object are first class cl_objects, they have their
456 * own radix trees of pages and hence page is implemented as a sequence of
457 * struct cl_pages's, linked into double-linked list through
458 * cl_page::cp_parent and cl_page::cp_child pointers, each residing in the
459 * corresponding radix tree at the corresponding logical offset.
461 * cl_page is associated with VM page of the hosting environment (struct
462 * page in Linux kernel, for example), cfs_page_t. It is assumed, that this
463 * association is implemented by one of cl_page layers (top layer in the
464 * current design) that
466 * - intercepts per-VM-page call-backs made by the environment (e.g.,
469 * - translates state (page flag bits) and locking between lustre and
472 * The association between cl_page and cfs_page_t is immutable and
473 * established when cl_page is created.
475 * cl_page can be "owned" by a particular cl_io (see below), guaranteeing
476 * this io an exclusive access to this page w.r.t. other io attempts and
477 * various events changing page state (such as transfer completion, or
478 * eviction of the page from the memory). Note, that in general cl_io
479 * cannot be identified with a particular thread, and page ownership is not
480 * exactly equal to the current thread holding a lock on the page. Layer
481 * implementing association between cl_page and cfs_page_t has to implement
482 * ownership on top of available synchronization mechanisms.
484 * While lustre client maintains the notion of an page ownership by io,
485 * hosting MM/VM usually has its own page concurrency control
486 * mechanisms. For example, in Linux, page access is synchronized by the
487 * per-page PG_locked bit-lock, and generic kernel code (generic_file_*())
488 * takes care to acquire and release such locks as necessary around the
489 * calls to the file system methods (->readpage(), ->prepare_write(),
490 * ->commit_write(), etc.). This leads to the situation when there are two
491 * different ways to own a page in the client:
493 * - client code explicitly and voluntary owns the page (cl_page_own());
495 * - VM locks a page and then calls the client, that has "to assume"
496 * the ownership from the VM (cl_page_assume()).
498 * Dual methods to release ownership are cl_page_disown() and
499 * cl_page_unassume().
501 * cl_page is reference counted (cl_page::cp_ref). When reference counter
502 * drops to 0, the page is returned to the cache, unless it is in
503 * cl_page_state::CPS_FREEING state, in which case it is immediately
506 * The general logic guaranteeing the absence of "existential races" for
507 * pages is the following:
509 * - there are fixed known ways for a thread to obtain a new reference
512 * - by doing a lookup in the cl_object radix tree, protected by the
515 * - by starting from VM-locked cfs_page_t and following some
516 * hosting environment method (e.g., following ->private pointer in
517 * the case of Linux kernel), see cl_vmpage_page();
519 * - when the page enters cl_page_state::CPS_FREEING state, all these
520 * ways are severed with the proper synchronization
521 * (cl_page_delete());
523 * - entry into cl_page_state::CPS_FREEING is serialized by the VM page
526 * - no new references to the page in cl_page_state::CPS_FREEING state
527 * are allowed (checked in cl_page_get()).
529 * Together this guarantees that when last reference to a
530 * cl_page_state::CPS_FREEING page is released, it is safe to destroy the
531 * page, as neither references to it can be acquired at that point, nor
534 * cl_page is a state machine. States are enumerated in enum
535 * cl_page_state. Possible state transitions are enumerated in
536 * cl_page_state_set(). State transition process (i.e., actual changing of
537 * cl_page::cp_state field) is protected by the lock on the underlying VM
540 * Linux Kernel implementation.
542 * Binding between cl_page and cfs_page_t (which is a typedef for
543 * struct page) is implemented in the vvp layer. cl_page is attached to the
544 * ->private pointer of the struct page, together with the setting of
545 * PG_private bit in page->flags, and acquiring additional reference on the
546 * struct page (much like struct buffer_head, or any similar file system
547 * private data structures).
549 * PG_locked lock is used to implement both ownership and transfer
550 * synchronization, that is, page is VM-locked in CPS_{OWNED,PAGE{IN,OUT}}
551 * states. No additional references are acquired for the duration of the
554 * \warning *THIS IS NOT* the behavior expected by the Linux kernel, where
555 * write-out is "protected" by the special PG_writeback bit.
559 * States of cl_page. cl_page.c assumes particular order here.
561 * The page state machine is rather crude, as it doesn't recognize finer page
562 * states like "dirty" or "up to date". This is because such states are not
563 * always well defined for the whole stack (see, for example, the
564 * implementation of the read-ahead, that hides page up-to-dateness to track
565 * cache hits accurately). Such sub-states are maintained by the layers that
566 * are interested in them.
570 * Page is in the cache, un-owned. Page leaves cached state in the
573 * - [cl_page_state::CPS_OWNED] io comes across the page and
576 * - [cl_page_state::CPS_PAGEOUT] page is dirty, the
577 * req-formation engine decides that it wants to include this page
578 * into an cl_req being constructed, and yanks it from the cache;
580 * - [cl_page_state::CPS_FREEING] VM callback is executed to
581 * evict the page form the memory;
583 * \invariant cl_page::cp_owner == NULL && cl_page::cp_req == NULL
587 * Page is exclusively owned by some cl_io. Page may end up in this
588 * state as a result of
590 * - io creating new page and immediately owning it;
592 * - [cl_page_state::CPS_CACHED] io finding existing cached page
595 * - [cl_page_state::CPS_OWNED] io finding existing owned page
596 * and waiting for owner to release the page;
598 * Page leaves owned state in the following cases:
600 * - [cl_page_state::CPS_CACHED] io decides to leave the page in
601 * the cache, doing nothing;
603 * - [cl_page_state::CPS_PAGEIN] io starts read transfer for
606 * - [cl_page_state::CPS_PAGEOUT] io starts immediate write
607 * transfer for this page;
609 * - [cl_page_state::CPS_FREEING] io decides to destroy this
610 * page (e.g., as part of truncate or extent lock cancellation).
612 * \invariant cl_page::cp_owner != NULL && cl_page::cp_req == NULL
616 * Page is being written out, as a part of a transfer. This state is
617 * entered when req-formation logic decided that it wants this page to
618 * be sent through the wire _now_. Specifically, it means that once
619 * this state is achieved, transfer completion handler (with either
620 * success or failure indication) is guaranteed to be executed against
621 * this page independently of any locks and any scheduling decisions
622 * made by the hosting environment (that effectively means that the
623 * page is never put into cl_page_state::CPS_PAGEOUT state "in
624 * advance". This property is mentioned, because it is important when
625 * reasoning about possible dead-locks in the system). The page can
626 * enter this state as a result of
628 * - [cl_page_state::CPS_OWNED] an io requesting an immediate
629 * write-out of this page, or
631 * - [cl_page_state::CPS_CACHED] req-forming engine deciding
632 * that it has enough dirty pages cached to issue a "good"
635 * The page leaves cl_page_state::CPS_PAGEOUT state when the transfer
636 * is completed---it is moved into cl_page_state::CPS_CACHED state.
638 * Underlying VM page is locked for the duration of transfer.
640 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL
644 * Page is being read in, as a part of a transfer. This is quite
645 * similar to the cl_page_state::CPS_PAGEOUT state, except that
646 * read-in is always "immediate"---there is no such thing a sudden
647 * construction of read cl_req from cached, presumably not up to date,
650 * Underlying VM page is locked for the duration of transfer.
652 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL
656 * Page is being destroyed. This state is entered when client decides
657 * that page has to be deleted from its host object, as, e.g., a part
660 * Once this state is reached, there is no way to escape it.
662 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req == NULL
669 /** Host page, the page is from the host inode which the cl_page
673 /** Transient page, the transient cl_page is used to bind a cl_page
674 * to vmpage which is not belonging to the same object of cl_page.
675 * it is used in DirectIO, lockless IO and liblustre. */
680 * Flags maintained for every cl_page.
684 * Set when pagein completes. Used for debugging (read completes at
685 * most once for a page).
687 CPF_READ_COMPLETED = 1 << 0
691 * Fields are protected by the lock on cfs_page_t, except for atomics and
694 * \invariant Data type invariants are in cl_page_invariant(). Basically:
695 * cl_page::cp_parent and cl_page::cp_child are a well-formed double-linked
696 * list, consistent with the parent/child pointers in the cl_page::cp_obj and
697 * cl_page::cp_owner (when set).
700 /** Reference counter. */
702 /** An object this page is a part of. Immutable after creation. */
703 struct cl_object *cp_obj;
704 /** Logical page index within the object. Immutable after creation. */
706 /** List of slices. Immutable after creation. */
707 cfs_list_t cp_layers;
708 /** Parent page, NULL for top-level page. Immutable after creation. */
709 struct cl_page *cp_parent;
710 /** Lower-layer page. NULL for bottommost page. Immutable after
712 struct cl_page *cp_child;
714 * Page state. This field is const to avoid accidental update, it is
715 * modified only internally within cl_page.c. Protected by a VM lock.
717 const enum cl_page_state cp_state;
719 * Linkage of pages within some group. Protected by
720 * cl_page::cp_mutex. */
722 /** Mutex serializing membership of a page in a batch. */
723 cfs_mutex_t cp_mutex;
724 /** Linkage of pages within cl_req. */
725 cfs_list_t cp_flight;
726 /** Transfer error. */
730 * Page type. Only CPT_TRANSIENT is used so far. Immutable after
733 enum cl_page_type cp_type;
736 * Owning IO in cl_page_state::CPS_OWNED state. Sub-page can be owned
737 * by sub-io. Protected by a VM lock.
739 struct cl_io *cp_owner;
741 * Debug information, the task is owning the page.
745 * Owning IO request in cl_page_state::CPS_PAGEOUT and
746 * cl_page_state::CPS_PAGEIN states. This field is maintained only in
747 * the top-level pages. Protected by a VM lock.
749 struct cl_req *cp_req;
750 /** List of references to this page, for debugging. */
751 struct lu_ref cp_reference;
752 /** Link to an object, for debugging. */
753 struct lu_ref_link *cp_obj_ref;
754 /** Link to a queue, for debugging. */
755 struct lu_ref_link *cp_queue_ref;
756 /** Per-page flags from enum cl_page_flags. Protected by a VM lock. */
758 /** Assigned if doing a sync_io */
759 struct cl_sync_io *cp_sync_io;
763 * Per-layer part of cl_page.
765 * \see ccc_page, lov_page, osc_page
767 struct cl_page_slice {
768 struct cl_page *cpl_page;
770 * Object slice corresponding to this page slice. Immutable after
773 struct cl_object *cpl_obj;
774 const struct cl_page_operations *cpl_ops;
775 /** Linkage into cl_page::cp_layers. Immutable after creation. */
776 cfs_list_t cpl_linkage;
780 * Lock mode. For the client extent locks.
782 * \warning: cl_lock_mode_match() assumes particular ordering here.
787 * Mode of a lock that protects no data, and exists only as a
788 * placeholder. This is used for `glimpse' requests. A phantom lock
789 * might get promoted to real lock at some point.
798 * Requested transfer type.
808 * Per-layer page operations.
810 * Methods taking an \a io argument are for the activity happening in the
811 * context of given \a io. Page is assumed to be owned by that io, except for
812 * the obvious cases (like cl_page_operations::cpo_own()).
814 * \see vvp_page_ops, lov_page_ops, osc_page_ops
816 struct cl_page_operations {
818 * cl_page<->cfs_page_t methods. Only one layer in the stack has to
819 * implement these. Current code assumes that this functionality is
820 * provided by the topmost layer, see cl_page_disown0() as an example.
824 * \return the underlying VM page. Optional.
826 cfs_page_t *(*cpo_vmpage)(const struct lu_env *env,
827 const struct cl_page_slice *slice);
829 * Called when \a io acquires this page into the exclusive
830 * ownership. When this method returns, it is guaranteed that the is
831 * not owned by other io, and no transfer is going on against
835 * \see vvp_page_own(), lov_page_own()
837 int (*cpo_own)(const struct lu_env *env,
838 const struct cl_page_slice *slice,
839 struct cl_io *io, int nonblock);
840 /** Called when ownership it yielded. Optional.
842 * \see cl_page_disown()
843 * \see vvp_page_disown()
845 void (*cpo_disown)(const struct lu_env *env,
846 const struct cl_page_slice *slice, struct cl_io *io);
848 * Called for a page that is already "owned" by \a io from VM point of
851 * \see cl_page_assume()
852 * \see vvp_page_assume(), lov_page_assume()
854 void (*cpo_assume)(const struct lu_env *env,
855 const struct cl_page_slice *slice, struct cl_io *io);
856 /** Dual to cl_page_operations::cpo_assume(). Optional. Called
857 * bottom-to-top when IO releases a page without actually unlocking
860 * \see cl_page_unassume()
861 * \see vvp_page_unassume()
863 void (*cpo_unassume)(const struct lu_env *env,
864 const struct cl_page_slice *slice,
867 * Announces whether the page contains valid data or not by \a uptodate.
869 * \see cl_page_export()
870 * \see vvp_page_export()
872 void (*cpo_export)(const struct lu_env *env,
873 const struct cl_page_slice *slice, int uptodate);
875 * Unmaps page from the user space (if it is mapped).
877 * \see cl_page_unmap()
878 * \see vvp_page_unmap()
880 int (*cpo_unmap)(const struct lu_env *env,
881 const struct cl_page_slice *slice, struct cl_io *io);
883 * Checks whether underlying VM page is locked (in the suitable
884 * sense). Used for assertions.
886 * \retval -EBUSY: page is protected by a lock of a given mode;
887 * \retval -ENODATA: page is not protected by a lock;
888 * \retval 0: this layer cannot decide. (Should never happen.)
890 int (*cpo_is_vmlocked)(const struct lu_env *env,
891 const struct cl_page_slice *slice);
897 * Called when page is truncated from the object. Optional.
899 * \see cl_page_discard()
900 * \see vvp_page_discard(), osc_page_discard()
902 void (*cpo_discard)(const struct lu_env *env,
903 const struct cl_page_slice *slice,
906 * Called when page is removed from the cache, and is about to being
907 * destroyed. Optional.
909 * \see cl_page_delete()
910 * \see vvp_page_delete(), osc_page_delete()
912 void (*cpo_delete)(const struct lu_env *env,
913 const struct cl_page_slice *slice);
914 /** Destructor. Frees resources and slice itself. */
915 void (*cpo_fini)(const struct lu_env *env,
916 struct cl_page_slice *slice);
919 * Checks whether the page is protected by a cl_lock. This is a
920 * per-layer method, because certain layers have ways to check for the
921 * lock much more efficiently than through the generic locks scan, or
922 * implement locking mechanisms separate from cl_lock, e.g.,
923 * LL_FILE_GROUP_LOCKED in vvp. If \a pending is true, check for locks
924 * being canceled, or scheduled for cancellation as soon as the last
925 * user goes away, too.
927 * \retval -EBUSY: page is protected by a lock of a given mode;
928 * \retval -ENODATA: page is not protected by a lock;
929 * \retval 0: this layer cannot decide.
931 * \see cl_page_is_under_lock()
933 int (*cpo_is_under_lock)(const struct lu_env *env,
934 const struct cl_page_slice *slice,
938 * Optional debugging helper. Prints given page slice.
940 * \see cl_page_print()
942 int (*cpo_print)(const struct lu_env *env,
943 const struct cl_page_slice *slice,
944 void *cookie, lu_printer_t p);
948 * Transfer methods. See comment on cl_req for a description of
949 * transfer formation and life-cycle.
954 * Request type dependent vector of operations.
956 * Transfer operations depend on transfer mode (cl_req_type). To avoid
957 * passing transfer mode to each and every of these methods, and to
958 * avoid branching on request type inside of the methods, separate
959 * methods for cl_req_type:CRT_READ and cl_req_type:CRT_WRITE are
960 * provided. That is, method invocation usually looks like
962 * slice->cp_ops.io[req->crq_type].cpo_method(env, slice, ...);
966 * Called when a page is submitted for a transfer as a part of
969 * \return 0 : page is eligible for submission;
970 * \return -EALREADY : skip this page;
971 * \return -ve : error.
973 * \see cl_page_prep()
975 int (*cpo_prep)(const struct lu_env *env,
976 const struct cl_page_slice *slice,
979 * Completion handler. This is guaranteed to be eventually
980 * fired after cl_page_operations::cpo_prep() or
981 * cl_page_operations::cpo_make_ready() call.
983 * This method can be called in a non-blocking context. It is
984 * guaranteed however, that the page involved and its object
985 * are pinned in memory (and, hence, calling cl_page_put() is
988 * \see cl_page_completion()
990 void (*cpo_completion)(const struct lu_env *env,
991 const struct cl_page_slice *slice,
994 * Called when cached page is about to be added to the
995 * cl_req as a part of req formation.
997 * \return 0 : proceed with this page;
998 * \return -EAGAIN : skip this page;
999 * \return -ve : error.
1001 * \see cl_page_make_ready()
1003 int (*cpo_make_ready)(const struct lu_env *env,
1004 const struct cl_page_slice *slice);
1006 * Announce that this page is to be written out
1007 * opportunistically, that is, page is dirty, it is not
1008 * necessary to start write-out transfer right now, but
1009 * eventually page has to be written out.
1011 * Main caller of this is the write path (see
1012 * vvp_io_commit_write()), using this method to build a
1013 * "transfer cache" from which large transfers are then
1014 * constructed by the req-formation engine.
1016 * \todo XXX it would make sense to add page-age tracking
1017 * semantics here, and to oblige the req-formation engine to
1018 * send the page out not later than it is too old.
1020 * \see cl_page_cache_add()
1022 int (*cpo_cache_add)(const struct lu_env *env,
1023 const struct cl_page_slice *slice,
1027 * Tell transfer engine that only [to, from] part of a page should be
1030 * This is used for immediate transfers.
1032 * \todo XXX this is not very good interface. It would be much better
1033 * if all transfer parameters were supplied as arguments to
1034 * cl_io_operations::cio_submit() call, but it is not clear how to do
1035 * this for page queues.
1037 * \see cl_page_clip()
1039 void (*cpo_clip)(const struct lu_env *env,
1040 const struct cl_page_slice *slice,
1043 * \pre the page was queued for transferring.
1044 * \post page is removed from client's pending list, or -EBUSY
1045 * is returned if it has already been in transferring.
1047 * This is one of seldom page operation which is:
1048 * 0. called from top level;
1049 * 1. don't have vmpage locked;
1050 * 2. every layer should synchronize execution of its ->cpo_cancel()
1051 * with completion handlers. Osc uses client obd lock for this
1052 * purpose. Based on there is no vvp_page_cancel and
1053 * lov_page_cancel(), cpo_cancel is defacto protected by client lock.
1055 * \see osc_page_cancel().
1057 int (*cpo_cancel)(const struct lu_env *env,
1058 const struct cl_page_slice *slice);
1063 * Helper macro, dumping detailed information about \a page into a log.
1065 #define CL_PAGE_DEBUG(mask, env, page, format, ...) \
1067 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1069 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1070 cl_page_print(env, &msgdata, lu_cdebug_printer, page); \
1071 CDEBUG(mask, format , ## __VA_ARGS__); \
1076 * Helper macro, dumping shorter information about \a page into a log.
1078 #define CL_PAGE_HEADER(mask, env, page, format, ...) \
1080 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1082 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1083 cl_page_header_print(env, &msgdata, lu_cdebug_printer, page); \
1084 CDEBUG(mask, format , ## __VA_ARGS__); \
1090 /** \addtogroup cl_lock cl_lock
1094 * Extent locking on the client.
1098 * The locking model of the new client code is built around
1102 * data-type representing an extent lock on a regular file. cl_lock is a
1103 * layered object (much like cl_object and cl_page), it consists of a header
1104 * (struct cl_lock) and a list of layers (struct cl_lock_slice), linked to
1105 * cl_lock::cll_layers list through cl_lock_slice::cls_linkage.
1107 * All locks for a given object are linked into cl_object_header::coh_locks
1108 * list (protected by cl_object_header::coh_lock_guard spin-lock) through
1109 * cl_lock::cll_linkage. Currently this list is not sorted in any way. We can
1110 * sort it in starting lock offset, or use altogether different data structure
1113 * Typical cl_lock consists of the two layers:
1115 * - vvp_lock (vvp specific data), and
1116 * - lov_lock (lov specific data).
1118 * lov_lock contains an array of sub-locks. Each of these sub-locks is a
1119 * normal cl_lock: it has a header (struct cl_lock) and a list of layers:
1121 * - lovsub_lock, and
1124 * Each sub-lock is associated with a cl_object (representing stripe
1125 * sub-object or the file to which top-level cl_lock is associated to), and is
1126 * linked into that cl_object::coh_locks. In this respect cl_lock is similar to
1127 * cl_object (that at lov layer also fans out into multiple sub-objects), and
1128 * is different from cl_page, that doesn't fan out (there is usually exactly
1129 * one osc_page for every vvp_page). We shall call vvp-lov portion of the lock
1130 * a "top-lock" and its lovsub-osc portion a "sub-lock".
1134 * cl_lock is reference counted. When reference counter drops to 0, lock is
1135 * placed in the cache, except when lock is in CLS_FREEING state. CLS_FREEING
1136 * lock is destroyed when last reference is released. Referencing between
1137 * top-lock and its sub-locks is described in the lov documentation module.
1141 * Also, cl_lock is a state machine. This requires some clarification. One of
1142 * the goals of client IO re-write was to make IO path non-blocking, or at
1143 * least to make it easier to make it non-blocking in the future. Here
1144 * `non-blocking' means that when a system call (read, write, truncate)
1145 * reaches a situation where it has to wait for a communication with the
1146 * server, it should --instead of waiting-- remember its current state and
1147 * switch to some other work. E.g,. instead of waiting for a lock enqueue,
1148 * client should proceed doing IO on the next stripe, etc. Obviously this is
1149 * rather radical redesign, and it is not planned to be fully implemented at
1150 * this time, instead we are putting some infrastructure in place, that would
1151 * make it easier to do asynchronous non-blocking IO easier in the
1152 * future. Specifically, where old locking code goes to sleep (waiting for
1153 * enqueue, for example), new code returns cl_lock_transition::CLO_WAIT. When
1154 * enqueue reply comes, its completion handler signals that lock state-machine
1155 * is ready to transit to the next state. There is some generic code in
1156 * cl_lock.c that sleeps, waiting for these signals. As a result, for users of
1157 * this cl_lock.c code, it looks like locking is done in normal blocking
1158 * fashion, and it the same time it is possible to switch to the non-blocking
1159 * locking (simply by returning cl_lock_transition::CLO_WAIT from cl_lock.c
1162 * For a description of state machine states and transitions see enum
1165 * There are two ways to restrict a set of states which lock might move to:
1167 * - placing a "hold" on a lock guarantees that lock will not be moved
1168 * into cl_lock_state::CLS_FREEING state until hold is released. Hold
1169 * can be only acquired on a lock that is not in
1170 * cl_lock_state::CLS_FREEING. All holds on a lock are counted in
1171 * cl_lock::cll_holds. Hold protects lock from cancellation and
1172 * destruction. Requests to cancel and destroy a lock on hold will be
1173 * recorded, but only honored when last hold on a lock is released;
1175 * - placing a "user" on a lock guarantees that lock will not leave
1176 * cl_lock_state::CLS_NEW, cl_lock_state::CLS_QUEUING,
1177 * cl_lock_state::CLS_ENQUEUED and cl_lock_state::CLS_HELD set of
1178 * states, once it enters this set. That is, if a user is added onto a
1179 * lock in a state not from this set, it doesn't immediately enforce
1180 * lock to move to this set, but once lock enters this set it will
1181 * remain there until all users are removed. Lock users are counted in
1182 * cl_lock::cll_users.
1184 * User is used to assure that lock is not canceled or destroyed while
1185 * it is being enqueued, or actively used by some IO.
1187 * Currently, a user always comes with a hold (cl_lock_invariant()
1188 * checks that a number of holds is not less than a number of users).
1192 * This is how lock state-machine operates. struct cl_lock contains a mutex
1193 * cl_lock::cll_guard that protects struct fields.
1195 * - mutex is taken, and cl_lock::cll_state is examined.
1197 * - for every state there are possible target states where lock can move
1198 * into. They are tried in order. Attempts to move into next state are
1199 * done by _try() functions in cl_lock.c:cl_{enqueue,unlock,wait}_try().
1201 * - if the transition can be performed immediately, state is changed,
1202 * and mutex is released.
1204 * - if the transition requires blocking, _try() function returns
1205 * cl_lock_transition::CLO_WAIT. Caller unlocks mutex and goes to
1206 * sleep, waiting for possibility of lock state change. It is woken
1207 * up when some event occurs, that makes lock state change possible
1208 * (e.g., the reception of the reply from the server), and repeats
1211 * Top-lock and sub-lock has separate mutexes and the latter has to be taken
1212 * first to avoid dead-lock.
1214 * To see an example of interaction of all these issues, take a look at the
1215 * lov_cl.c:lov_lock_enqueue() function. It is called as a part of
1216 * cl_enqueue_try(), and tries to advance top-lock to ENQUEUED state, by
1217 * advancing state-machines of its sub-locks (lov_lock_enqueue_one()). Note
1218 * also, that it uses trylock to grab sub-lock mutex to avoid dead-lock. It
1219 * also has to handle CEF_ASYNC enqueue, when sub-locks enqueues have to be
1220 * done in parallel, rather than one after another (this is used for glimpse
1221 * locks, that cannot dead-lock).
1223 * INTERFACE AND USAGE
1225 * struct cl_lock_operations provide a number of call-backs that are invoked
1226 * when events of interest occurs. Layers can intercept and handle glimpse,
1227 * blocking, cancel ASTs and a reception of the reply from the server.
1229 * One important difference with the old client locking model is that new
1230 * client has a representation for the top-lock, whereas in the old code only
1231 * sub-locks existed as real data structures and file-level locks are
1232 * represented by "request sets" that are created and destroyed on each and
1233 * every lock creation.
1235 * Top-locks are cached, and can be found in the cache by the system calls. It
1236 * is possible that top-lock is in cache, but some of its sub-locks were
1237 * canceled and destroyed. In that case top-lock has to be enqueued again
1238 * before it can be used.
1240 * Overall process of the locking during IO operation is as following:
1242 * - once parameters for IO are setup in cl_io, cl_io_operations::cio_lock()
1243 * is called on each layer. Responsibility of this method is to add locks,
1244 * needed by a given layer into cl_io.ci_lockset.
1246 * - once locks for all layers were collected, they are sorted to avoid
1247 * dead-locks (cl_io_locks_sort()), and enqueued.
1249 * - when all locks are acquired, IO is performed;
1251 * - locks are released into cache.
1253 * Striping introduces major additional complexity into locking. The
1254 * fundamental problem is that it is generally unsafe to actively use (hold)
1255 * two locks on the different OST servers at the same time, as this introduces
1256 * inter-server dependency and can lead to cascading evictions.
1258 * Basic solution is to sub-divide large read/write IOs into smaller pieces so
1259 * that no multi-stripe locks are taken (note that this design abandons POSIX
1260 * read/write semantics). Such pieces ideally can be executed concurrently. At
1261 * the same time, certain types of IO cannot be sub-divived, without
1262 * sacrificing correctness. This includes:
1264 * - O_APPEND write, where [0, EOF] lock has to be taken, to guarantee
1267 * - ftruncate(fd, offset), where [offset, EOF] lock has to be taken.
1269 * Also, in the case of read(fd, buf, count) or write(fd, buf, count), where
1270 * buf is a part of memory mapped Lustre file, a lock or locks protecting buf
1271 * has to be held together with the usual lock on [offset, offset + count].
1273 * As multi-stripe locks have to be allowed, it makes sense to cache them, so
1274 * that, for example, a sequence of O_APPEND writes can proceed quickly
1275 * without going down to the individual stripes to do lock matching. On the
1276 * other hand, multi-stripe locks shouldn't be used by normal read/write
1277 * calls. To achieve this, every layer can implement ->clo_fits_into() method,
1278 * that is called by lock matching code (cl_lock_lookup()), and that can be
1279 * used to selectively disable matching of certain locks for certain IOs. For
1280 * exmaple, lov layer implements lov_lock_fits_into() that allow multi-stripe
1281 * locks to be matched only for truncates and O_APPEND writes.
1283 * Interaction with DLM
1285 * In the expected setup, cl_lock is ultimately backed up by a collection of
1286 * DLM locks (struct ldlm_lock). Association between cl_lock and DLM lock is
1287 * implemented in osc layer, that also matches DLM events (ASTs, cancellation,
1288 * etc.) into cl_lock_operation calls. See struct osc_lock for a more detailed
1289 * description of interaction with DLM.
1295 struct cl_lock_descr {
1296 /** Object this lock is granted for. */
1297 struct cl_object *cld_obj;
1298 /** Index of the first page protected by this lock. */
1300 /** Index of the last page (inclusive) protected by this lock. */
1302 /** Group ID, for group lock */
1305 enum cl_lock_mode cld_mode;
1307 * flags to enqueue lock. A combination of bit-flags from
1308 * enum cl_enq_flags.
1310 __u32 cld_enq_flags;
1313 #define DDESCR "%s(%d):[%lu, %lu]"
1314 #define PDESCR(descr) \
1315 cl_lock_mode_name((descr)->cld_mode), (descr)->cld_mode, \
1316 (descr)->cld_start, (descr)->cld_end
1318 const char *cl_lock_mode_name(const enum cl_lock_mode mode);
1321 * Lock state-machine states.
1326 * Possible state transitions:
1328 * +------------------>NEW
1330 * | | cl_enqueue_try()
1332 * | cl_unuse_try() V
1333 * | +--------------QUEUING (*)
1335 * | | | cl_enqueue_try()
1337 * | | cl_unuse_try() V
1338 * sub-lock | +-------------ENQUEUED (*)
1340 * | | | cl_wait_try()
1345 * | | HELD<---------+
1347 * | | | | cl_use_try()
1348 * | | cl_unuse_try() | |
1351 * | +------------>INTRANSIT (D) <--+
1353 * | cl_unuse_try() | | cached lock found
1354 * | | | cl_use_try()
1357 * +------------------CACHED---------+
1366 * In states marked with (*) transition to the same state (i.e., a loop
1367 * in the diagram) is possible.
1369 * (R) is the point where Receive call-back is invoked: it allows layers
1370 * to handle arrival of lock reply.
1372 * (C) is the point where Cancellation call-back is invoked.
1374 * (D) is the transit state which means the lock is changing.
1376 * Transition to FREEING state is possible from any other state in the
1377 * diagram in case of unrecoverable error.
1381 * These states are for individual cl_lock object. Top-lock and its sub-locks
1382 * can be in the different states. Another way to say this is that we have
1383 * nested state-machines.
1385 * Separate QUEUING and ENQUEUED states are needed to support non-blocking
1386 * operation for locks with multiple sub-locks. Imagine lock on a file F, that
1387 * intersects 3 stripes S0, S1, and S2. To enqueue F client has to send
1388 * enqueue to S0, wait for its completion, then send enqueue for S1, wait for
1389 * its completion and at last enqueue lock for S2, and wait for its
1390 * completion. In that case, top-lock is in QUEUING state while S0, S1 are
1391 * handled, and is in ENQUEUED state after enqueue to S2 has been sent (note
1392 * that in this case, sub-locks move from state to state, and top-lock remains
1393 * in the same state).
1395 enum cl_lock_state {
1397 * Lock that wasn't yet enqueued
1401 * Enqueue is in progress, blocking for some intermediate interaction
1402 * with the other side.
1406 * Lock is fully enqueued, waiting for server to reply when it is
1411 * Lock granted, actively used by some IO.
1415 * This state is used to mark the lock is being used, or unused.
1416 * We need this state because the lock may have several sublocks,
1417 * so it's impossible to have an atomic way to bring all sublocks
1418 * into CLS_HELD state at use case, or all sublocks to CLS_CACHED
1420 * If a thread is referring to a lock, and it sees the lock is in this
1421 * state, it must wait for the lock.
1422 * See state diagram for details.
1426 * Lock granted, not used.
1430 * Lock is being destroyed.
1436 enum cl_lock_flags {
1438 * lock has been cancelled. This flag is never cleared once set (by
1439 * cl_lock_cancel0()).
1441 CLF_CANCELLED = 1 << 0,
1442 /** cancellation is pending for this lock. */
1443 CLF_CANCELPEND = 1 << 1,
1444 /** destruction is pending for this lock. */
1451 * Lock closure is a collection of locks (both top-locks and sub-locks) that
1452 * might be updated in a result of an operation on a certain lock (which lock
1453 * this is a closure of).
1455 * Closures are needed to guarantee dead-lock freedom in the presence of
1457 * - nested state-machines (top-lock state-machine composed of sub-lock
1458 * state-machines), and
1460 * - shared sub-locks.
1462 * Specifically, many operations, such as lock enqueue, wait, unlock,
1463 * etc. start from a top-lock, and then operate on a sub-locks of this
1464 * top-lock, holding a top-lock mutex. When sub-lock state changes as a result
1465 * of such operation, this change has to be propagated to all top-locks that
1466 * share this sub-lock. Obviously, no natural lock ordering (e.g.,
1467 * top-to-bottom or bottom-to-top) captures this scenario, so try-locking has
1468 * to be used. Lock closure systematizes this try-and-repeat logic.
1470 struct cl_lock_closure {
1472 * Lock that is mutexed when closure construction is started. When
1473 * closure in is `wait' mode (cl_lock_closure::clc_wait), mutex on
1474 * origin is released before waiting.
1476 struct cl_lock *clc_origin;
1478 * List of enclosed locks, so far. Locks are linked here through
1479 * cl_lock::cll_inclosure.
1481 cfs_list_t clc_list;
1483 * True iff closure is in a `wait' mode. This determines what
1484 * cl_lock_enclosure() does when a lock L to be added to the closure
1485 * is currently mutexed by some other thread.
1487 * If cl_lock_closure::clc_wait is not set, then closure construction
1488 * fails with CLO_REPEAT immediately.
1490 * In wait mode, cl_lock_enclosure() waits until next attempt to build
1491 * a closure might succeed. To this end it releases an origin mutex
1492 * (cl_lock_closure::clc_origin), that has to be the only lock mutex
1493 * owned by the current thread, and then waits on L mutex (by grabbing
1494 * it and immediately releasing), before returning CLO_REPEAT to the
1498 /** Number of locks in the closure. */
1503 * Layered client lock.
1506 /** Reference counter. */
1507 cfs_atomic_t cll_ref;
1508 /** List of slices. Immutable after creation. */
1509 cfs_list_t cll_layers;
1511 * Linkage into cl_lock::cll_descr::cld_obj::coh_locks list. Protected
1512 * by cl_lock::cll_descr::cld_obj::coh_lock_guard.
1514 cfs_list_t cll_linkage;
1516 * Parameters of this lock. Protected by
1517 * cl_lock::cll_descr::cld_obj::coh_lock_guard nested within
1518 * cl_lock::cll_guard. Modified only on lock creation and in
1521 struct cl_lock_descr cll_descr;
1522 /** Protected by cl_lock::cll_guard. */
1523 enum cl_lock_state cll_state;
1524 /** signals state changes. */
1527 * Recursive lock, most fields in cl_lock{} are protected by this.
1529 * Locking rules: this mutex is never held across network
1530 * communication, except when lock is being canceled.
1532 * Lock ordering: a mutex of a sub-lock is taken first, then a mutex
1533 * on a top-lock. Other direction is implemented through a
1534 * try-lock-repeat loop. Mutices of unrelated locks can be taken only
1537 * \see osc_lock_enqueue_wait(), lov_lock_cancel(), lov_sublock_wait().
1539 cfs_mutex_t cll_guard;
1540 cfs_task_t *cll_guarder;
1544 * the owner for INTRANSIT state
1546 cfs_task_t *cll_intransit_owner;
1549 * Number of holds on a lock. A hold prevents a lock from being
1550 * canceled and destroyed. Protected by cl_lock::cll_guard.
1552 * \see cl_lock_hold(), cl_lock_unhold(), cl_lock_release()
1556 * Number of lock users. Valid in cl_lock_state::CLS_HELD state
1557 * only. Lock user pins lock in CLS_HELD state. Protected by
1558 * cl_lock::cll_guard.
1560 * \see cl_wait(), cl_unuse().
1564 * Flag bit-mask. Values from enum cl_lock_flags. Updates are
1565 * protected by cl_lock::cll_guard.
1567 unsigned long cll_flags;
1569 * A linkage into a list of locks in a closure.
1571 * \see cl_lock_closure
1573 cfs_list_t cll_inclosure;
1575 * Confict lock at queuing time.
1577 struct cl_lock *cll_conflict;
1579 * A list of references to this lock, for debugging.
1581 struct lu_ref cll_reference;
1583 * A list of holds on this lock, for debugging.
1585 struct lu_ref cll_holders;
1587 * A reference for cl_lock::cll_descr::cld_obj. For debugging.
1589 struct lu_ref_link *cll_obj_ref;
1590 #ifdef CONFIG_LOCKDEP
1591 /* "dep_map" name is assumed by lockdep.h macros. */
1592 struct lockdep_map dep_map;
1597 * Per-layer part of cl_lock
1599 * \see ccc_lock, lov_lock, lovsub_lock, osc_lock
1601 struct cl_lock_slice {
1602 struct cl_lock *cls_lock;
1603 /** Object slice corresponding to this lock slice. Immutable after
1605 struct cl_object *cls_obj;
1606 const struct cl_lock_operations *cls_ops;
1607 /** Linkage into cl_lock::cll_layers. Immutable after creation. */
1608 cfs_list_t cls_linkage;
1612 * Possible (non-error) return values of ->clo_{enqueue,wait,unlock}().
1614 * NOTE: lov_subresult() depends on ordering here.
1616 enum cl_lock_transition {
1617 /** operation cannot be completed immediately. Wait for state change. */
1619 /** operation had to release lock mutex, restart. */
1621 /** lower layer re-enqueued. */
1627 * \see vvp_lock_ops, lov_lock_ops, lovsub_lock_ops, osc_lock_ops
1629 struct cl_lock_operations {
1631 * \name statemachine
1633 * State machine transitions. These 3 methods are called to transfer
1634 * lock from one state to another, as described in the commentary
1635 * above enum #cl_lock_state.
1637 * \retval 0 this layer has nothing more to do to before
1638 * transition to the target state happens;
1640 * \retval CLO_REPEAT method had to release and re-acquire cl_lock
1641 * mutex, repeat invocation of transition method
1642 * across all layers;
1644 * \retval CLO_WAIT this layer cannot move to the target state
1645 * immediately, as it has to wait for certain event
1646 * (e.g., the communication with the server). It
1647 * is guaranteed, that when the state transfer
1648 * becomes possible, cl_lock::cll_wq wait-queue
1649 * is signaled. Caller can wait for this event by
1650 * calling cl_lock_state_wait();
1652 * \retval -ve failure, abort state transition, move the lock
1653 * into cl_lock_state::CLS_FREEING state, and set
1654 * cl_lock::cll_error.
1656 * Once all layers voted to agree to transition (by returning 0), lock
1657 * is moved into corresponding target state. All state transition
1658 * methods are optional.
1662 * Attempts to enqueue the lock. Called top-to-bottom.
1664 * \see ccc_lock_enqueue(), lov_lock_enqueue(), lovsub_lock_enqueue(),
1665 * \see osc_lock_enqueue()
1667 int (*clo_enqueue)(const struct lu_env *env,
1668 const struct cl_lock_slice *slice,
1669 struct cl_io *io, __u32 enqflags);
1671 * Attempts to wait for enqueue result. Called top-to-bottom.
1673 * \see ccc_lock_wait(), lov_lock_wait(), osc_lock_wait()
1675 int (*clo_wait)(const struct lu_env *env,
1676 const struct cl_lock_slice *slice);
1678 * Attempts to unlock the lock. Called bottom-to-top. In addition to
1679 * usual return values of lock state-machine methods, this can return
1680 * -ESTALE to indicate that lock cannot be returned to the cache, and
1681 * has to be re-initialized.
1682 * unuse is a one-shot operation, so it must NOT return CLO_WAIT.
1684 * \see ccc_lock_unuse(), lov_lock_unuse(), osc_lock_unuse()
1686 int (*clo_unuse)(const struct lu_env *env,
1687 const struct cl_lock_slice *slice);
1689 * Notifies layer that cached lock is started being used.
1691 * \pre lock->cll_state == CLS_CACHED
1693 * \see lov_lock_use(), osc_lock_use()
1695 int (*clo_use)(const struct lu_env *env,
1696 const struct cl_lock_slice *slice);
1697 /** @} statemachine */
1699 * A method invoked when lock state is changed (as a result of state
1700 * transition). This is used, for example, to track when the state of
1701 * a sub-lock changes, to propagate this change to the corresponding
1702 * top-lock. Optional
1704 * \see lovsub_lock_state()
1706 void (*clo_state)(const struct lu_env *env,
1707 const struct cl_lock_slice *slice,
1708 enum cl_lock_state st);
1710 * Returns true, iff given lock is suitable for the given io, idea
1711 * being, that there are certain "unsafe" locks, e.g., ones acquired
1712 * for O_APPEND writes, that we don't want to re-use for a normal
1713 * write, to avoid the danger of cascading evictions. Optional. Runs
1714 * under cl_object_header::coh_lock_guard.
1716 * XXX this should take more information about lock needed by
1717 * io. Probably lock description or something similar.
1719 * \see lov_fits_into()
1721 int (*clo_fits_into)(const struct lu_env *env,
1722 const struct cl_lock_slice *slice,
1723 const struct cl_lock_descr *need,
1724 const struct cl_io *io);
1727 * Asynchronous System Traps. All of then are optional, all are
1728 * executed bottom-to-top.
1733 * Cancellation callback. Cancel a lock voluntarily, or under
1734 * the request of server.
1736 void (*clo_cancel)(const struct lu_env *env,
1737 const struct cl_lock_slice *slice);
1739 * Lock weighting ast. Executed to estimate how precious this lock
1740 * is. The sum of results across all layers is used to determine
1741 * whether lock worth keeping in cache given present memory usage.
1743 * \see osc_lock_weigh(), vvp_lock_weigh(), lovsub_lock_weigh().
1745 unsigned long (*clo_weigh)(const struct lu_env *env,
1746 const struct cl_lock_slice *slice);
1750 * \see lovsub_lock_closure()
1752 int (*clo_closure)(const struct lu_env *env,
1753 const struct cl_lock_slice *slice,
1754 struct cl_lock_closure *closure);
1756 * Executed bottom-to-top when lock description changes (e.g., as a
1757 * result of server granting more generous lock than was requested).
1759 * \see lovsub_lock_modify()
1761 int (*clo_modify)(const struct lu_env *env,
1762 const struct cl_lock_slice *slice,
1763 const struct cl_lock_descr *updated);
1765 * Notifies layers (bottom-to-top) that lock is going to be
1766 * destroyed. Responsibility of layers is to prevent new references on
1767 * this lock from being acquired once this method returns.
1769 * This can be called multiple times due to the races.
1771 * \see cl_lock_delete()
1772 * \see osc_lock_delete(), lovsub_lock_delete()
1774 void (*clo_delete)(const struct lu_env *env,
1775 const struct cl_lock_slice *slice);
1777 * Destructor. Frees resources and the slice.
1779 * \see ccc_lock_fini(), lov_lock_fini(), lovsub_lock_fini(),
1780 * \see osc_lock_fini()
1782 void (*clo_fini)(const struct lu_env *env, struct cl_lock_slice *slice);
1784 * Optional debugging helper. Prints given lock slice.
1786 int (*clo_print)(const struct lu_env *env,
1787 void *cookie, lu_printer_t p,
1788 const struct cl_lock_slice *slice);
1791 #define CL_LOCK_DEBUG(mask, env, lock, format, ...) \
1793 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1795 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1796 cl_lock_print(env, &msgdata, lu_cdebug_printer, lock); \
1797 CDEBUG(mask, format , ## __VA_ARGS__); \
1803 /** \addtogroup cl_page_list cl_page_list
1804 * Page list used to perform collective operations on a group of pages.
1806 * Pages are added to the list one by one. cl_page_list acquires a reference
1807 * for every page in it. Page list is used to perform collective operations on
1810 * - submit pages for an immediate transfer,
1812 * - own pages on behalf of certain io (waiting for each page in turn),
1816 * When list is finalized, it releases references on all pages it still has.
1818 * \todo XXX concurrency control.
1822 struct cl_page_list {
1824 cfs_list_t pl_pages;
1825 cfs_task_t *pl_owner;
1829 * A 2-queue of pages. A convenience data-type for common use case, 2-queue
1830 * contains an incoming page list and an outgoing page list.
1833 struct cl_page_list c2_qin;
1834 struct cl_page_list c2_qout;
1837 /** @} cl_page_list */
1839 /** \addtogroup cl_io cl_io
1844 * cl_io represents a high level I/O activity like
1845 * read(2)/write(2)/truncate(2) system call, or cancellation of an extent
1848 * cl_io is a layered object, much like cl_{object,page,lock} but with one
1849 * important distinction. We want to minimize number of calls to the allocator
1850 * in the fast path, e.g., in the case of read(2) when everything is cached:
1851 * client already owns the lock over region being read, and data are cached
1852 * due to read-ahead. To avoid allocation of cl_io layers in such situations,
1853 * per-layer io state is stored in the session, associated with the io, see
1854 * struct {vvp,lov,osc}_io for example. Sessions allocation is amortized
1855 * by using free-lists, see cl_env_get().
1857 * There is a small predefined number of possible io types, enumerated in enum
1860 * cl_io is a state machine, that can be advanced concurrently by the multiple
1861 * threads. It is up to these threads to control the concurrency and,
1862 * specifically, to detect when io is done, and its state can be safely
1865 * For read/write io overall execution plan is as following:
1867 * (0) initialize io state through all layers;
1869 * (1) loop: prepare chunk of work to do
1871 * (2) call all layers to collect locks they need to process current chunk
1873 * (3) sort all locks to avoid dead-locks, and acquire them
1875 * (4) process the chunk: call per-page methods
1876 * (cl_io_operations::cio_read_page() for read,
1877 * cl_io_operations::cio_prepare_write(),
1878 * cl_io_operations::cio_commit_write() for write)
1884 * To implement the "parallel IO mode", lov layer creates sub-io's (lazily to
1885 * address allocation efficiency issues mentioned above), and returns with the
1886 * special error condition from per-page method when current sub-io has to
1887 * block. This causes io loop to be repeated, and lov switches to the next
1888 * sub-io in its cl_io_operations::cio_iter_init() implementation.
1893 /** read system call */
1895 /** write system call */
1897 /** truncate, utime system calls */
1900 * page fault handling
1904 * Miscellaneous io. This is used for occasional io activity that
1905 * doesn't fit into other types. Currently this is used for:
1907 * - cancellation of an extent lock. This io exists as a context
1908 * to write dirty pages from under the lock being canceled back
1911 * - VM induced page write-out. An io context for writing page out
1912 * for memory cleansing;
1914 * - glimpse. An io context to acquire glimpse lock.
1916 * - grouplock. An io context to acquire group lock.
1918 * CIT_MISC io is used simply as a context in which locks and pages
1919 * are manipulated. Such io has no internal "process", that is,
1920 * cl_io_loop() is never called for it.
1927 * States of cl_io state machine
1930 /** Not initialized. */
1934 /** IO iteration started. */
1938 /** Actual IO is in progress. */
1940 /** IO for the current iteration finished. */
1942 /** Locks released. */
1944 /** Iteration completed. */
1946 /** cl_io finalized. */
1950 enum cl_req_priority {
1956 * IO state private for a layer.
1958 * This is usually embedded into layer session data, rather than allocated
1961 * \see vvp_io, lov_io, osc_io, ccc_io
1963 struct cl_io_slice {
1964 struct cl_io *cis_io;
1965 /** corresponding object slice. Immutable after creation. */
1966 struct cl_object *cis_obj;
1967 /** io operations. Immutable after creation. */
1968 const struct cl_io_operations *cis_iop;
1970 * linkage into a list of all slices for a given cl_io, hanging off
1971 * cl_io::ci_layers. Immutable after creation.
1973 cfs_list_t cis_linkage;
1978 * Per-layer io operations.
1979 * \see vvp_io_ops, lov_io_ops, lovsub_io_ops, osc_io_ops
1981 struct cl_io_operations {
1983 * Vector of io state transition methods for every io type.
1985 * \see cl_page_operations::io
1989 * Prepare io iteration at a given layer.
1991 * Called top-to-bottom at the beginning of each iteration of
1992 * "io loop" (if it makes sense for this type of io). Here
1993 * layer selects what work it will do during this iteration.
1995 * \see cl_io_operations::cio_iter_fini()
1997 int (*cio_iter_init) (const struct lu_env *env,
1998 const struct cl_io_slice *slice);
2000 * Finalize io iteration.
2002 * Called bottom-to-top at the end of each iteration of "io
2003 * loop". Here layers can decide whether IO has to be
2006 * \see cl_io_operations::cio_iter_init()
2008 void (*cio_iter_fini) (const struct lu_env *env,
2009 const struct cl_io_slice *slice);
2011 * Collect locks for the current iteration of io.
2013 * Called top-to-bottom to collect all locks necessary for
2014 * this iteration. This methods shouldn't actually enqueue
2015 * anything, instead it should post a lock through
2016 * cl_io_lock_add(). Once all locks are collected, they are
2017 * sorted and enqueued in the proper order.
2019 int (*cio_lock) (const struct lu_env *env,
2020 const struct cl_io_slice *slice);
2022 * Finalize unlocking.
2024 * Called bottom-to-top to finish layer specific unlocking
2025 * functionality, after generic code released all locks
2026 * acquired by cl_io_operations::cio_lock().
2028 void (*cio_unlock)(const struct lu_env *env,
2029 const struct cl_io_slice *slice);
2031 * Start io iteration.
2033 * Once all locks are acquired, called top-to-bottom to
2034 * commence actual IO. In the current implementation,
2035 * top-level vvp_io_{read,write}_start() does all the work
2036 * synchronously by calling generic_file_*(), so other layers
2037 * are called when everything is done.
2039 int (*cio_start)(const struct lu_env *env,
2040 const struct cl_io_slice *slice);
2042 * Called top-to-bottom at the end of io loop. Here layer
2043 * might wait for an unfinished asynchronous io.
2045 void (*cio_end) (const struct lu_env *env,
2046 const struct cl_io_slice *slice);
2048 * Called bottom-to-top to notify layers that read/write IO
2049 * iteration finished, with \a nob bytes transferred.
2051 void (*cio_advance)(const struct lu_env *env,
2052 const struct cl_io_slice *slice,
2055 * Called once per io, bottom-to-top to release io resources.
2057 void (*cio_fini) (const struct lu_env *env,
2058 const struct cl_io_slice *slice);
2062 * Submit pages from \a queue->c2_qin for IO, and move
2063 * successfully submitted pages into \a queue->c2_qout. Return
2064 * non-zero if failed to submit even the single page. If
2065 * submission failed after some pages were moved into \a
2066 * queue->c2_qout, completion callback with non-zero ioret is
2069 int (*cio_submit)(const struct lu_env *env,
2070 const struct cl_io_slice *slice,
2071 enum cl_req_type crt,
2072 struct cl_2queue *queue,
2073 enum cl_req_priority priority);
2076 * Read missing page.
2078 * Called by a top-level cl_io_operations::op[CIT_READ]::cio_start()
2079 * method, when it hits not-up-to-date page in the range. Optional.
2081 * \pre io->ci_type == CIT_READ
2083 int (*cio_read_page)(const struct lu_env *env,
2084 const struct cl_io_slice *slice,
2085 const struct cl_page_slice *page);
2087 * Prepare write of a \a page. Called bottom-to-top by a top-level
2088 * cl_io_operations::op[CIT_WRITE]::cio_start() to prepare page for
2089 * get data from user-level buffer.
2091 * \pre io->ci_type == CIT_WRITE
2093 * \see vvp_io_prepare_write(), lov_io_prepare_write(),
2094 * osc_io_prepare_write().
2096 int (*cio_prepare_write)(const struct lu_env *env,
2097 const struct cl_io_slice *slice,
2098 const struct cl_page_slice *page,
2099 unsigned from, unsigned to);
2102 * \pre io->ci_type == CIT_WRITE
2104 * \see vvp_io_commit_write(), lov_io_commit_write(),
2105 * osc_io_commit_write().
2107 int (*cio_commit_write)(const struct lu_env *env,
2108 const struct cl_io_slice *slice,
2109 const struct cl_page_slice *page,
2110 unsigned from, unsigned to);
2112 * Optional debugging helper. Print given io slice.
2114 int (*cio_print)(const struct lu_env *env, void *cookie,
2115 lu_printer_t p, const struct cl_io_slice *slice);
2119 * Flags to lock enqueue procedure.
2124 * instruct server to not block, if conflicting lock is found. Instead
2125 * -EWOULDBLOCK is returned immediately.
2127 CEF_NONBLOCK = 0x00000001,
2129 * take lock asynchronously (out of order), as it cannot
2130 * deadlock. This is for LDLM_FL_HAS_INTENT locks used for glimpsing.
2132 CEF_ASYNC = 0x00000002,
2134 * tell the server to instruct (though a flag in the blocking ast) an
2135 * owner of the conflicting lock, that it can drop dirty pages
2136 * protected by this lock, without sending them to the server.
2138 CEF_DISCARD_DATA = 0x00000004,
2140 * tell the sub layers that it must be a `real' lock. This is used for
2141 * mmapped-buffer locks and glimpse locks that must be never converted
2142 * into lockless mode.
2144 * \see vvp_mmap_locks(), cl_glimpse_lock().
2146 CEF_MUST = 0x00000008,
2148 * tell the sub layers that never request a `real' lock. This flag is
2149 * not used currently.
2151 * cl_io::ci_lockreq and CEF_{MUST,NEVER} flags specify lockless
2152 * conversion policy: ci_lockreq describes generic information of lock
2153 * requirement for this IO, especially for locks which belong to the
2154 * object doing IO; however, lock itself may have precise requirements
2155 * that are described by the enqueue flags.
2157 CEF_NEVER = 0x00000010,
2159 * for async glimpse lock.
2161 CEF_AGL = 0x00000020,
2163 * do not trigger re-enqueue.
2165 CEF_NO_REENQUEUE = 0x00000040,
2167 * mask of enq_flags.
2169 CEF_MASK = 0x0000007f,
2173 * Link between lock and io. Intermediate structure is needed, because the
2174 * same lock can be part of multiple io's simultaneously.
2176 struct cl_io_lock_link {
2177 /** linkage into one of cl_lockset lists. */
2178 cfs_list_t cill_linkage;
2179 struct cl_lock_descr cill_descr;
2180 struct cl_lock *cill_lock;
2181 /** optional destructor */
2182 void (*cill_fini)(const struct lu_env *env,
2183 struct cl_io_lock_link *link);
2187 * Lock-set represents a collection of locks, that io needs at a
2188 * time. Generally speaking, client tries to avoid holding multiple locks when
2191 * - holding extent locks over multiple ost's introduces the danger of
2192 * "cascading timeouts";
2194 * - holding multiple locks over the same ost is still dead-lock prone,
2195 * see comment in osc_lock_enqueue(),
2197 * but there are certain situations where this is unavoidable:
2199 * - O_APPEND writes have to take [0, EOF] lock for correctness;
2201 * - truncate has to take [new-size, EOF] lock for correctness;
2203 * - SNS has to take locks across full stripe for correctness;
2205 * - in the case when user level buffer, supplied to {read,write}(file0),
2206 * is a part of a memory mapped lustre file, client has to take a dlm
2207 * locks on file0, and all files that back up the buffer (or a part of
2208 * the buffer, that is being processed in the current chunk, in any
2209 * case, there are situations where at least 2 locks are necessary).
2211 * In such cases we at least try to take locks in the same consistent
2212 * order. To this end, all locks are first collected, then sorted, and then
2216 /** locks to be acquired. */
2217 cfs_list_t cls_todo;
2218 /** locks currently being processed. */
2219 cfs_list_t cls_curr;
2220 /** locks acquired. */
2221 cfs_list_t cls_done;
2225 * Lock requirements(demand) for IO. It should be cl_io_lock_req,
2226 * but 'req' is always to be thought as 'request' :-)
2228 enum cl_io_lock_dmd {
2229 /** Always lock data (e.g., O_APPEND). */
2231 /** Layers are free to decide between local and global locking. */
2233 /** Never lock: there is no cache (e.g., liblustre). */
2235 /** Peek lock: use existing locks, don't queue new ones */
2239 struct cl_io_rw_common {
2249 * cl_io is shared by all threads participating in this IO (in current
2250 * implementation only one thread advances IO, but parallel IO design and
2251 * concurrent copy_*_user() require multiple threads acting on the same IO. It
2252 * is up to these threads to serialize their activities, including updates to
2253 * mutable cl_io fields.
2256 /** type of this IO. Immutable after creation. */
2257 enum cl_io_type ci_type;
2258 /** current state of cl_io state machine. */
2259 enum cl_io_state ci_state;
2260 /** main object this io is against. Immutable after creation. */
2261 struct cl_object *ci_obj;
2263 * Upper layer io, of which this io is a part of. Immutable after
2266 struct cl_io *ci_parent;
2267 /** List of slices. Immutable after creation. */
2268 cfs_list_t ci_layers;
2269 /** list of locks (to be) acquired by this io. */
2270 struct cl_lockset ci_lockset;
2271 /** lock requirements, this is just a help info for sublayers. */
2272 enum cl_io_lock_dmd ci_lockreq;
2274 * This io has held grouplock, to inform sublayers that
2275 * don't do lockless i/o.
2280 struct cl_io_rw_common rd;
2283 struct cl_io_rw_common wr;
2286 struct cl_io_rw_common ci_rw;
2287 struct cl_setattr_io {
2288 struct ost_lvb sa_attr;
2289 unsigned int sa_valid;
2290 struct obd_capa *sa_capa;
2292 struct cl_fault_io {
2293 /** page index within file. */
2295 /** bytes valid byte on a faulted page. */
2297 /** writable page? for nopage() only */
2299 /** page of an executable? */
2301 /** page_mkwrite() */
2303 /** resulting page */
2304 struct cl_page *ft_page;
2307 struct cl_2queue ci_queue;
2312 * Number of pages owned by this IO. For invariant checking.
2314 unsigned ci_owned_nr;
2319 /** \addtogroup cl_req cl_req
2324 * There are two possible modes of transfer initiation on the client:
2326 * - immediate transfer: this is started when a high level io wants a page
2327 * or a collection of pages to be transferred right away. Examples:
2328 * read-ahead, synchronous read in the case of non-page aligned write,
2329 * page write-out as a part of extent lock cancellation, page write-out
2330 * as a part of memory cleansing. Immediate transfer can be both
2331 * cl_req_type::CRT_READ and cl_req_type::CRT_WRITE;
2333 * - opportunistic transfer (cl_req_type::CRT_WRITE only), that happens
2334 * when io wants to transfer a page to the server some time later, when
2335 * it can be done efficiently. Example: pages dirtied by the write(2)
2338 * In any case, transfer takes place in the form of a cl_req, which is a
2339 * representation for a network RPC.
2341 * Pages queued for an opportunistic transfer are cached until it is decided
2342 * that efficient RPC can be composed of them. This decision is made by "a
2343 * req-formation engine", currently implemented as a part of osc
2344 * layer. Req-formation depends on many factors: the size of the resulting
2345 * RPC, whether or not multi-object RPCs are supported by the server,
2346 * max-rpc-in-flight limitations, size of the dirty cache, etc.
2348 * For the immediate transfer io submits a cl_page_list, that req-formation
2349 * engine slices into cl_req's, possibly adding cached pages to some of
2350 * the resulting req's.
2352 * Whenever a page from cl_page_list is added to a newly constructed req, its
2353 * cl_page_operations::cpo_prep() layer methods are called. At that moment,
2354 * page state is atomically changed from cl_page_state::CPS_OWNED to
2355 * cl_page_state::CPS_PAGEOUT or cl_page_state::CPS_PAGEIN, cl_page::cp_owner
2356 * is zeroed, and cl_page::cp_req is set to the
2357 * req. cl_page_operations::cpo_prep() method at the particular layer might
2358 * return -EALREADY to indicate that it does not need to submit this page
2359 * at all. This is possible, for example, if page, submitted for read,
2360 * became up-to-date in the meantime; and for write, the page don't have
2361 * dirty bit marked. \see cl_io_submit_rw()
2363 * Whenever a cached page is added to a newly constructed req, its
2364 * cl_page_operations::cpo_make_ready() layer methods are called. At that
2365 * moment, page state is atomically changed from cl_page_state::CPS_CACHED to
2366 * cl_page_state::CPS_PAGEOUT, and cl_page::cp_req is set to
2367 * req. cl_page_operations::cpo_make_ready() method at the particular layer
2368 * might return -EAGAIN to indicate that this page is not eligible for the
2369 * transfer right now.
2373 * Plan is to divide transfers into "priority bands" (indicated when
2374 * submitting cl_page_list, and queuing a page for the opportunistic transfer)
2375 * and allow glueing of cached pages to immediate transfers only within single
2376 * band. This would make high priority transfers (like lock cancellation or
2377 * memory pressure induced write-out) really high priority.
2382 * Per-transfer attributes.
2384 struct cl_req_attr {
2385 /** Generic attributes for the server consumption. */
2386 struct obdo *cra_oa;
2388 struct obd_capa *cra_capa;
2392 * Transfer request operations definable at every layer.
2394 * Concurrency: transfer formation engine synchronizes calls to all transfer
2397 struct cl_req_operations {
2399 * Invoked top-to-bottom by cl_req_prep() when transfer formation is
2400 * complete (all pages are added).
2402 * \see osc_req_prep()
2404 int (*cro_prep)(const struct lu_env *env,
2405 const struct cl_req_slice *slice);
2407 * Called top-to-bottom to fill in \a oa fields. This is called twice
2408 * with different flags, see bug 10150 and osc_build_req().
2410 * \param obj an object from cl_req which attributes are to be set in
2413 * \param oa struct obdo where attributes are placed
2415 * \param flags \a oa fields to be filled.
2417 void (*cro_attr_set)(const struct lu_env *env,
2418 const struct cl_req_slice *slice,
2419 const struct cl_object *obj,
2420 struct cl_req_attr *attr, obd_valid flags);
2422 * Called top-to-bottom from cl_req_completion() to notify layers that
2423 * transfer completed. Has to free all state allocated by
2424 * cl_device_operations::cdo_req_init().
2426 void (*cro_completion)(const struct lu_env *env,
2427 const struct cl_req_slice *slice, int ioret);
2431 * A per-object state that (potentially multi-object) transfer request keeps.
2434 /** object itself */
2435 struct cl_object *ro_obj;
2436 /** reference to cl_req_obj::ro_obj. For debugging. */
2437 struct lu_ref_link *ro_obj_ref;
2438 /* something else? Number of pages for a given object? */
2444 * Transfer requests are not reference counted, because IO sub-system owns
2445 * them exclusively and knows when to free them.
2449 * cl_req is created by cl_req_alloc() that calls
2450 * cl_device_operations::cdo_req_init() device methods to allocate per-req
2451 * state in every layer.
2453 * Then pages are added (cl_req_page_add()), req keeps track of all objects it
2454 * contains pages for.
2456 * Once all pages were collected, cl_page_operations::cpo_prep() method is
2457 * called top-to-bottom. At that point layers can modify req, let it pass, or
2458 * deny it completely. This is to support things like SNS that have transfer
2459 * ordering requirements invisible to the individual req-formation engine.
2461 * On transfer completion (or transfer timeout, or failure to initiate the
2462 * transfer of an allocated req), cl_req_operations::cro_completion() method
2463 * is called, after execution of cl_page_operations::cpo_completion() of all
2467 enum cl_req_type crq_type;
2468 /** A list of pages being transfered */
2469 cfs_list_t crq_pages;
2470 /** Number of pages in cl_req::crq_pages */
2471 unsigned crq_nrpages;
2472 /** An array of objects which pages are in ->crq_pages */
2473 struct cl_req_obj *crq_o;
2474 /** Number of elements in cl_req::crq_objs[] */
2475 unsigned crq_nrobjs;
2476 cfs_list_t crq_layers;
2480 * Per-layer state for request.
2482 struct cl_req_slice {
2483 struct cl_req *crs_req;
2484 struct cl_device *crs_dev;
2485 cfs_list_t crs_linkage;
2486 const struct cl_req_operations *crs_ops;
2492 * Stats for a generic cache (similar to inode, lu_object, etc. caches).
2494 struct cache_stats {
2495 const char *cs_name;
2496 /** how many entities were created at all */
2497 cfs_atomic_t cs_created;
2498 /** how many cache lookups were performed */
2499 cfs_atomic_t cs_lookup;
2500 /** how many times cache lookup resulted in a hit */
2501 cfs_atomic_t cs_hit;
2502 /** how many entities are in the cache right now */
2503 cfs_atomic_t cs_total;
2504 /** how many entities in the cache are actively used (and cannot be
2505 * evicted) right now */
2506 cfs_atomic_t cs_busy;
2509 /** These are not exported so far */
2510 void cache_stats_init (struct cache_stats *cs, const char *name);
2511 int cache_stats_print(const struct cache_stats *cs,
2512 char *page, int count, int header);
2515 * Client-side site. This represents particular client stack. "Global"
2516 * variables should (directly or indirectly) be added here to allow multiple
2517 * clients to co-exist in the single address space.
2520 struct lu_site cs_lu;
2522 * Statistical counters. Atomics do not scale, something better like
2523 * per-cpu counters is needed.
2525 * These are exported as /proc/fs/lustre/llite/.../site
2527 * When interpreting keep in mind that both sub-locks (and sub-pages)
2528 * and top-locks (and top-pages) are accounted here.
2530 struct cache_stats cs_pages;
2531 struct cache_stats cs_locks;
2532 cfs_atomic_t cs_pages_state[CPS_NR];
2533 cfs_atomic_t cs_locks_state[CLS_NR];
2536 int cl_site_init (struct cl_site *s, struct cl_device *top);
2537 void cl_site_fini (struct cl_site *s);
2538 void cl_stack_fini(const struct lu_env *env, struct cl_device *cl);
2541 * Output client site statistical counters into a buffer. Suitable for
2542 * ll_rd_*()-style functions.
2544 int cl_site_stats_print(const struct cl_site *s, char *page, int count);
2549 * Type conversion and accessory functions.
2553 static inline struct cl_site *lu2cl_site(const struct lu_site *site)
2555 return container_of(site, struct cl_site, cs_lu);
2558 static inline int lu_device_is_cl(const struct lu_device *d)
2560 return d->ld_type->ldt_tags & LU_DEVICE_CL;
2563 static inline struct cl_device *lu2cl_dev(const struct lu_device *d)
2565 LASSERT(d == NULL || IS_ERR(d) || lu_device_is_cl(d));
2566 return container_of0(d, struct cl_device, cd_lu_dev);
2569 static inline struct lu_device *cl2lu_dev(struct cl_device *d)
2571 return &d->cd_lu_dev;
2574 static inline struct cl_object *lu2cl(const struct lu_object *o)
2576 LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->lo_dev));
2577 return container_of0(o, struct cl_object, co_lu);
2580 static inline const struct cl_object_conf *
2581 lu2cl_conf(const struct lu_object_conf *conf)
2583 return container_of0(conf, struct cl_object_conf, coc_lu);
2586 static inline struct cl_object *cl_object_next(const struct cl_object *obj)
2588 return obj ? lu2cl(lu_object_next(&obj->co_lu)) : NULL;
2591 static inline struct cl_device *cl_object_device(const struct cl_object *o)
2593 LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->co_lu.lo_dev));
2594 return container_of0(o->co_lu.lo_dev, struct cl_device, cd_lu_dev);
2597 static inline struct cl_object_header *luh2coh(const struct lu_object_header *h)
2599 return container_of0(h, struct cl_object_header, coh_lu);
2602 static inline struct cl_site *cl_object_site(const struct cl_object *obj)
2604 return lu2cl_site(obj->co_lu.lo_dev->ld_site);
2608 struct cl_object_header *cl_object_header(const struct cl_object *obj)
2610 return luh2coh(obj->co_lu.lo_header);
2613 static inline int cl_device_init(struct cl_device *d, struct lu_device_type *t)
2615 return lu_device_init(&d->cd_lu_dev, t);
2618 static inline void cl_device_fini(struct cl_device *d)
2620 lu_device_fini(&d->cd_lu_dev);
2623 void cl_page_slice_add(struct cl_page *page, struct cl_page_slice *slice,
2624 struct cl_object *obj,
2625 const struct cl_page_operations *ops);
2626 void cl_lock_slice_add(struct cl_lock *lock, struct cl_lock_slice *slice,
2627 struct cl_object *obj,
2628 const struct cl_lock_operations *ops);
2629 void cl_io_slice_add(struct cl_io *io, struct cl_io_slice *slice,
2630 struct cl_object *obj, const struct cl_io_operations *ops);
2631 void cl_req_slice_add(struct cl_req *req, struct cl_req_slice *slice,
2632 struct cl_device *dev,
2633 const struct cl_req_operations *ops);
2636 /** \defgroup cl_object cl_object
2638 struct cl_object *cl_object_top (struct cl_object *o);
2639 struct cl_object *cl_object_find(const struct lu_env *env, struct cl_device *cd,
2640 const struct lu_fid *fid,
2641 const struct cl_object_conf *c);
2643 int cl_object_header_init(struct cl_object_header *h);
2644 void cl_object_header_fini(struct cl_object_header *h);
2645 void cl_object_put (const struct lu_env *env, struct cl_object *o);
2646 void cl_object_get (struct cl_object *o);
2647 void cl_object_attr_lock (struct cl_object *o);
2648 void cl_object_attr_unlock(struct cl_object *o);
2649 int cl_object_attr_get (const struct lu_env *env, struct cl_object *obj,
2650 struct cl_attr *attr);
2651 int cl_object_attr_set (const struct lu_env *env, struct cl_object *obj,
2652 const struct cl_attr *attr, unsigned valid);
2653 int cl_object_glimpse (const struct lu_env *env, struct cl_object *obj,
2654 struct ost_lvb *lvb);
2655 int cl_conf_set (const struct lu_env *env, struct cl_object *obj,
2656 const struct cl_object_conf *conf);
2657 void cl_object_prune (const struct lu_env *env, struct cl_object *obj);
2658 void cl_object_kill (const struct lu_env *env, struct cl_object *obj);
2659 int cl_object_has_locks (struct cl_object *obj);
2662 * Returns true, iff \a o0 and \a o1 are slices of the same object.
2664 static inline int cl_object_same(struct cl_object *o0, struct cl_object *o1)
2666 return cl_object_header(o0) == cl_object_header(o1);
2671 /** \defgroup cl_page cl_page
2680 /* callback of cl_page_gang_lookup() */
2681 typedef int (*cl_page_gang_cb_t) (const struct lu_env *, struct cl_io *,
2682 struct cl_page *, void *);
2683 int cl_page_gang_lookup (const struct lu_env *env,
2684 struct cl_object *obj,
2686 pgoff_t start, pgoff_t end,
2687 cl_page_gang_cb_t cb, void *cbdata);
2688 struct cl_page *cl_page_lookup (struct cl_object_header *hdr,
2690 struct cl_page *cl_page_find (const struct lu_env *env,
2691 struct cl_object *obj,
2692 pgoff_t idx, struct page *vmpage,
2693 enum cl_page_type type);
2694 struct cl_page *cl_page_find_sub (const struct lu_env *env,
2695 struct cl_object *obj,
2696 pgoff_t idx, struct page *vmpage,
2697 struct cl_page *parent);
2698 void cl_page_get (struct cl_page *page);
2699 void cl_page_put (const struct lu_env *env,
2700 struct cl_page *page);
2701 void cl_page_print (const struct lu_env *env, void *cookie,
2702 lu_printer_t printer,
2703 const struct cl_page *pg);
2704 void cl_page_header_print(const struct lu_env *env, void *cookie,
2705 lu_printer_t printer,
2706 const struct cl_page *pg);
2707 cfs_page_t *cl_page_vmpage (const struct lu_env *env,
2708 struct cl_page *page);
2709 struct cl_page *cl_vmpage_page (cfs_page_t *vmpage, struct cl_object *obj);
2710 struct cl_page *cl_page_top (struct cl_page *page);
2712 const struct cl_page_slice *cl_page_at(const struct cl_page *page,
2713 const struct lu_device_type *dtype);
2718 * Functions dealing with the ownership of page by io.
2722 int cl_page_own (const struct lu_env *env,
2723 struct cl_io *io, struct cl_page *page);
2724 int cl_page_own_try (const struct lu_env *env,
2725 struct cl_io *io, struct cl_page *page);
2726 void cl_page_assume (const struct lu_env *env,
2727 struct cl_io *io, struct cl_page *page);
2728 void cl_page_unassume (const struct lu_env *env,
2729 struct cl_io *io, struct cl_page *pg);
2730 void cl_page_disown (const struct lu_env *env,
2731 struct cl_io *io, struct cl_page *page);
2732 int cl_page_is_owned (const struct cl_page *pg, const struct cl_io *io);
2739 * Functions dealing with the preparation of a page for a transfer, and
2740 * tracking transfer state.
2743 int cl_page_prep (const struct lu_env *env, struct cl_io *io,
2744 struct cl_page *pg, enum cl_req_type crt);
2745 void cl_page_completion (const struct lu_env *env,
2746 struct cl_page *pg, enum cl_req_type crt, int ioret);
2747 int cl_page_make_ready (const struct lu_env *env, struct cl_page *pg,
2748 enum cl_req_type crt);
2749 int cl_page_cache_add (const struct lu_env *env, struct cl_io *io,
2750 struct cl_page *pg, enum cl_req_type crt);
2751 void cl_page_clip (const struct lu_env *env, struct cl_page *pg,
2753 int cl_page_cancel (const struct lu_env *env, struct cl_page *page);
2759 * \name helper routines
2760 * Functions to discard, delete and export a cl_page.
2763 void cl_page_discard (const struct lu_env *env, struct cl_io *io,
2764 struct cl_page *pg);
2765 void cl_page_delete (const struct lu_env *env, struct cl_page *pg);
2766 int cl_page_unmap (const struct lu_env *env, struct cl_io *io,
2767 struct cl_page *pg);
2768 int cl_page_is_vmlocked (const struct lu_env *env,
2769 const struct cl_page *pg);
2770 void cl_page_export (const struct lu_env *env,
2771 struct cl_page *pg, int uptodate);
2772 int cl_page_is_under_lock(const struct lu_env *env, struct cl_io *io,
2773 struct cl_page *page);
2774 loff_t cl_offset (const struct cl_object *obj, pgoff_t idx);
2775 pgoff_t cl_index (const struct cl_object *obj, loff_t offset);
2776 int cl_page_size (const struct cl_object *obj);
2777 int cl_pages_prune (const struct lu_env *env, struct cl_object *obj);
2779 void cl_lock_print (const struct lu_env *env, void *cookie,
2780 lu_printer_t printer, const struct cl_lock *lock);
2781 void cl_lock_descr_print(const struct lu_env *env, void *cookie,
2782 lu_printer_t printer,
2783 const struct cl_lock_descr *descr);
2788 /** \defgroup cl_lock cl_lock
2791 struct cl_lock *cl_lock_hold(const struct lu_env *env, const struct cl_io *io,
2792 const struct cl_lock_descr *need,
2793 const char *scope, const void *source);
2794 struct cl_lock *cl_lock_peek(const struct lu_env *env, const struct cl_io *io,
2795 const struct cl_lock_descr *need,
2796 const char *scope, const void *source);
2797 struct cl_lock *cl_lock_request(const struct lu_env *env, struct cl_io *io,
2798 const struct cl_lock_descr *need,
2799 const char *scope, const void *source);
2800 struct cl_lock *cl_lock_at_page(const struct lu_env *env, struct cl_object *obj,
2801 struct cl_page *page, struct cl_lock *except,
2802 int pending, int canceld);
2804 const struct cl_lock_slice *cl_lock_at(const struct cl_lock *lock,
2805 const struct lu_device_type *dtype);
2807 void cl_lock_get (struct cl_lock *lock);
2808 void cl_lock_get_trust (struct cl_lock *lock);
2809 void cl_lock_put (const struct lu_env *env, struct cl_lock *lock);
2810 void cl_lock_hold_add (const struct lu_env *env, struct cl_lock *lock,
2811 const char *scope, const void *source);
2812 void cl_lock_unhold (const struct lu_env *env, struct cl_lock *lock,
2813 const char *scope, const void *source);
2814 void cl_lock_release (const struct lu_env *env, struct cl_lock *lock,
2815 const char *scope, const void *source);
2816 void cl_lock_user_add (const struct lu_env *env, struct cl_lock *lock);
2817 void cl_lock_user_del (const struct lu_env *env, struct cl_lock *lock);
2819 enum cl_lock_state cl_lock_intransit(const struct lu_env *env,
2820 struct cl_lock *lock);
2821 void cl_lock_extransit(const struct lu_env *env, struct cl_lock *lock,
2822 enum cl_lock_state state);
2823 int cl_lock_is_intransit(struct cl_lock *lock);
2825 int cl_lock_enqueue_wait(const struct lu_env *env, struct cl_lock *lock,
2828 /** \name statemachine statemachine
2829 * Interface to lock state machine consists of 3 parts:
2831 * - "try" functions that attempt to effect a state transition. If state
2832 * transition is not possible right now (e.g., if it has to wait for some
2833 * asynchronous event to occur), these functions return
2834 * cl_lock_transition::CLO_WAIT.
2836 * - "non-try" functions that implement synchronous blocking interface on
2837 * top of non-blocking "try" functions. These functions repeatedly call
2838 * corresponding "try" versions, and if state transition is not possible
2839 * immediately, wait for lock state change.
2841 * - methods from cl_lock_operations, called by "try" functions. Lock can
2842 * be advanced to the target state only when all layers voted that they
2843 * are ready for this transition. "Try" functions call methods under lock
2844 * mutex. If a layer had to release a mutex, it re-acquires it and returns
2845 * cl_lock_transition::CLO_REPEAT, causing "try" function to call all
2848 * TRY NON-TRY METHOD FINAL STATE
2850 * cl_enqueue_try() cl_enqueue() cl_lock_operations::clo_enqueue() CLS_ENQUEUED
2852 * cl_wait_try() cl_wait() cl_lock_operations::clo_wait() CLS_HELD
2854 * cl_unuse_try() cl_unuse() cl_lock_operations::clo_unuse() CLS_CACHED
2856 * cl_use_try() NONE cl_lock_operations::clo_use() CLS_HELD
2860 int cl_enqueue (const struct lu_env *env, struct cl_lock *lock,
2861 struct cl_io *io, __u32 flags);
2862 int cl_wait (const struct lu_env *env, struct cl_lock *lock);
2863 void cl_unuse (const struct lu_env *env, struct cl_lock *lock);
2864 int cl_enqueue_try(const struct lu_env *env, struct cl_lock *lock,
2865 struct cl_io *io, __u32 flags);
2866 int cl_unuse_try (const struct lu_env *env, struct cl_lock *lock);
2867 int cl_wait_try (const struct lu_env *env, struct cl_lock *lock);
2868 int cl_use_try (const struct lu_env *env, struct cl_lock *lock, int atomic);
2870 /** @} statemachine */
2872 void cl_lock_signal (const struct lu_env *env, struct cl_lock *lock);
2873 int cl_lock_state_wait (const struct lu_env *env, struct cl_lock *lock);
2874 void cl_lock_state_set (const struct lu_env *env, struct cl_lock *lock,
2875 enum cl_lock_state state);
2876 int cl_queue_match (const cfs_list_t *queue,
2877 const struct cl_lock_descr *need);
2879 void cl_lock_mutex_get (const struct lu_env *env, struct cl_lock *lock);
2880 int cl_lock_mutex_try (const struct lu_env *env, struct cl_lock *lock);
2881 void cl_lock_mutex_put (const struct lu_env *env, struct cl_lock *lock);
2882 int cl_lock_is_mutexed (struct cl_lock *lock);
2883 int cl_lock_nr_mutexed (const struct lu_env *env);
2884 int cl_lock_page_out (const struct lu_env *env, struct cl_lock *lock,
2886 int cl_lock_ext_match (const struct cl_lock_descr *has,
2887 const struct cl_lock_descr *need);
2888 int cl_lock_descr_match(const struct cl_lock_descr *has,
2889 const struct cl_lock_descr *need);
2890 int cl_lock_mode_match (enum cl_lock_mode has, enum cl_lock_mode need);
2891 int cl_lock_modify (const struct lu_env *env, struct cl_lock *lock,
2892 const struct cl_lock_descr *desc);
2894 void cl_lock_closure_init (const struct lu_env *env,
2895 struct cl_lock_closure *closure,
2896 struct cl_lock *origin, int wait);
2897 void cl_lock_closure_fini (struct cl_lock_closure *closure);
2898 int cl_lock_closure_build(const struct lu_env *env, struct cl_lock *lock,
2899 struct cl_lock_closure *closure);
2900 void cl_lock_disclosure (const struct lu_env *env,
2901 struct cl_lock_closure *closure);
2902 int cl_lock_enclosure (const struct lu_env *env, struct cl_lock *lock,
2903 struct cl_lock_closure *closure);
2905 void cl_lock_cancel(const struct lu_env *env, struct cl_lock *lock);
2906 void cl_lock_delete(const struct lu_env *env, struct cl_lock *lock);
2907 void cl_lock_error (const struct lu_env *env, struct cl_lock *lock, int error);
2908 void cl_locks_prune(const struct lu_env *env, struct cl_object *obj, int wait);
2910 unsigned long cl_lock_weigh(const struct lu_env *env, struct cl_lock *lock);
2914 /** \defgroup cl_io cl_io
2917 int cl_io_init (const struct lu_env *env, struct cl_io *io,
2918 enum cl_io_type iot, struct cl_object *obj);
2919 int cl_io_sub_init (const struct lu_env *env, struct cl_io *io,
2920 enum cl_io_type iot, struct cl_object *obj);
2921 int cl_io_rw_init (const struct lu_env *env, struct cl_io *io,
2922 enum cl_io_type iot, loff_t pos, size_t count);
2923 int cl_io_loop (const struct lu_env *env, struct cl_io *io);
2925 void cl_io_fini (const struct lu_env *env, struct cl_io *io);
2926 int cl_io_iter_init (const struct lu_env *env, struct cl_io *io);
2927 void cl_io_iter_fini (const struct lu_env *env, struct cl_io *io);
2928 int cl_io_lock (const struct lu_env *env, struct cl_io *io);
2929 void cl_io_unlock (const struct lu_env *env, struct cl_io *io);
2930 int cl_io_start (const struct lu_env *env, struct cl_io *io);
2931 void cl_io_end (const struct lu_env *env, struct cl_io *io);
2932 int cl_io_lock_add (const struct lu_env *env, struct cl_io *io,
2933 struct cl_io_lock_link *link);
2934 int cl_io_lock_alloc_add(const struct lu_env *env, struct cl_io *io,
2935 struct cl_lock_descr *descr);
2936 int cl_io_read_page (const struct lu_env *env, struct cl_io *io,
2937 struct cl_page *page);
2938 int cl_io_prepare_write(const struct lu_env *env, struct cl_io *io,
2939 struct cl_page *page, unsigned from, unsigned to);
2940 int cl_io_commit_write (const struct lu_env *env, struct cl_io *io,
2941 struct cl_page *page, unsigned from, unsigned to);
2942 int cl_io_submit_rw (const struct lu_env *env, struct cl_io *io,
2943 enum cl_req_type iot, struct cl_2queue *queue,
2944 enum cl_req_priority priority);
2945 int cl_io_submit_sync (const struct lu_env *env, struct cl_io *io,
2946 enum cl_req_type iot, struct cl_2queue *queue,
2947 enum cl_req_priority priority, long timeout);
2948 void cl_io_rw_advance (const struct lu_env *env, struct cl_io *io,
2950 int cl_io_cancel (const struct lu_env *env, struct cl_io *io,
2951 struct cl_page_list *queue);
2952 int cl_io_is_going (const struct lu_env *env);
2955 * True, iff \a io is an O_APPEND write(2).
2957 static inline int cl_io_is_append(const struct cl_io *io)
2959 return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_append;
2963 * True, iff \a io is a truncate(2).
2965 static inline int cl_io_is_trunc(const struct cl_io *io)
2967 return io->ci_type == CIT_SETATTR &&
2968 (io->u.ci_setattr.sa_valid & ATTR_SIZE);
2971 struct cl_io *cl_io_top(struct cl_io *io);
2973 void cl_io_print(const struct lu_env *env, void *cookie,
2974 lu_printer_t printer, const struct cl_io *io);
2976 #define CL_IO_SLICE_CLEAN(foo_io, base) \
2978 typeof(foo_io) __foo_io = (foo_io); \
2980 CLASSERT(offsetof(typeof(*__foo_io), base) == 0); \
2981 memset(&__foo_io->base + 1, 0, \
2982 (sizeof *__foo_io) - sizeof __foo_io->base); \
2987 /** \defgroup cl_page_list cl_page_list
2991 * Last page in the page list.
2993 static inline struct cl_page *cl_page_list_last(struct cl_page_list *plist)
2995 LASSERT(plist->pl_nr > 0);
2996 return cfs_list_entry(plist->pl_pages.prev, struct cl_page, cp_batch);
3000 * Iterate over pages in a page list.
3002 #define cl_page_list_for_each(page, list) \
3003 cfs_list_for_each_entry((page), &(list)->pl_pages, cp_batch)
3006 * Iterate over pages in a page list, taking possible removals into account.
3008 #define cl_page_list_for_each_safe(page, temp, list) \
3009 cfs_list_for_each_entry_safe((page), (temp), &(list)->pl_pages, cp_batch)
3011 void cl_page_list_init (struct cl_page_list *plist);
3012 void cl_page_list_add (struct cl_page_list *plist, struct cl_page *page);
3013 void cl_page_list_move (struct cl_page_list *dst, struct cl_page_list *src,
3014 struct cl_page *page);
3015 void cl_page_list_splice (struct cl_page_list *list,
3016 struct cl_page_list *head);
3017 void cl_page_list_del (const struct lu_env *env,
3018 struct cl_page_list *plist, struct cl_page *page);
3019 void cl_page_list_disown (const struct lu_env *env,
3020 struct cl_io *io, struct cl_page_list *plist);
3021 int cl_page_list_own (const struct lu_env *env,
3022 struct cl_io *io, struct cl_page_list *plist);
3023 void cl_page_list_assume (const struct lu_env *env,
3024 struct cl_io *io, struct cl_page_list *plist);
3025 void cl_page_list_discard(const struct lu_env *env,
3026 struct cl_io *io, struct cl_page_list *plist);
3027 int cl_page_list_unmap (const struct lu_env *env,
3028 struct cl_io *io, struct cl_page_list *plist);
3029 void cl_page_list_fini (const struct lu_env *env, struct cl_page_list *plist);
3031 void cl_2queue_init (struct cl_2queue *queue);
3032 void cl_2queue_add (struct cl_2queue *queue, struct cl_page *page);
3033 void cl_2queue_disown (const struct lu_env *env,
3034 struct cl_io *io, struct cl_2queue *queue);
3035 void cl_2queue_assume (const struct lu_env *env,
3036 struct cl_io *io, struct cl_2queue *queue);
3037 void cl_2queue_discard (const struct lu_env *env,
3038 struct cl_io *io, struct cl_2queue *queue);
3039 void cl_2queue_fini (const struct lu_env *env, struct cl_2queue *queue);
3040 void cl_2queue_init_page(struct cl_2queue *queue, struct cl_page *page);
3042 /** @} cl_page_list */
3044 /** \defgroup cl_req cl_req
3046 struct cl_req *cl_req_alloc(const struct lu_env *env, struct cl_page *page,
3047 enum cl_req_type crt, int nr_objects);
3049 void cl_req_page_add (const struct lu_env *env, struct cl_req *req,
3050 struct cl_page *page);
3051 void cl_req_page_done (const struct lu_env *env, struct cl_page *page);
3052 int cl_req_prep (const struct lu_env *env, struct cl_req *req);
3053 void cl_req_attr_set (const struct lu_env *env, struct cl_req *req,
3054 struct cl_req_attr *attr, obd_valid flags);
3055 void cl_req_completion(const struct lu_env *env, struct cl_req *req, int ioret);
3057 /** \defgroup cl_sync_io cl_sync_io
3061 * Anchor for synchronous transfer. This is allocated on a stack by thread
3062 * doing synchronous transfer, and a pointer to this structure is set up in
3063 * every page submitted for transfer. Transfer completion routine updates
3064 * anchor and wakes up waiting thread when transfer is complete.
3067 /** number of pages yet to be transferred. */
3068 cfs_atomic_t csi_sync_nr;
3069 /** completion to be signaled when transfer is complete. */
3070 cfs_waitq_t csi_waitq;
3075 void cl_sync_io_init(struct cl_sync_io *anchor, int nrpages);
3076 int cl_sync_io_wait(const struct lu_env *env, struct cl_io *io,
3077 struct cl_page_list *queue, struct cl_sync_io *anchor,
3079 void cl_sync_io_note(struct cl_sync_io *anchor, int ioret);
3081 /** @} cl_sync_io */
3085 /** \defgroup cl_env cl_env
3087 * lu_env handling for a client.
3089 * lu_env is an environment within which lustre code executes. Its major part
3090 * is lu_context---a fast memory allocation mechanism that is used to conserve
3091 * precious kernel stack space. Originally lu_env was designed for a server,
3094 * - there is a (mostly) fixed number of threads, and
3096 * - call chains have no non-lustre portions inserted between lustre code.
3098 * On a client both these assumtpion fails, because every user thread can
3099 * potentially execute lustre code as part of a system call, and lustre calls
3100 * into VFS or MM that call back into lustre.
3102 * To deal with that, cl_env wrapper functions implement the following
3105 * - allocation and destruction of environment is amortized by caching no
3106 * longer used environments instead of destroying them;
3108 * - there is a notion of "current" environment, attached to the kernel
3109 * data structure representing current thread Top-level lustre code
3110 * allocates an environment and makes it current, then calls into
3111 * non-lustre code, that in turn calls lustre back. Low-level lustre
3112 * code thus called can fetch environment created by the top-level code
3113 * and reuse it, avoiding additional environment allocation.
3114 * Right now, three interfaces can attach the cl_env to running thread:
3117 * - cl_env_reexit(cl_env_reenter had to be called priorly)
3119 * \see lu_env, lu_context, lu_context_key
3122 struct cl_env_nest {
3127 struct lu_env *cl_env_peek (int *refcheck);
3128 struct lu_env *cl_env_get (int *refcheck);
3129 struct lu_env *cl_env_alloc (int *refcheck, __u32 tags);
3130 struct lu_env *cl_env_nested_get (struct cl_env_nest *nest);
3131 void cl_env_put (struct lu_env *env, int *refcheck);
3132 void cl_env_nested_put (struct cl_env_nest *nest, struct lu_env *env);
3133 void *cl_env_reenter (void);
3134 void cl_env_reexit (void *cookie);
3135 void cl_env_implant (struct lu_env *env, int *refcheck);
3136 void cl_env_unplant (struct lu_env *env, int *refcheck);
3137 unsigned cl_env_cache_purge(unsigned nr);
3144 void cl_attr2lvb(struct ost_lvb *lvb, const struct cl_attr *attr);
3145 void cl_lvb2attr(struct cl_attr *attr, const struct ost_lvb *lvb);
3147 struct cl_device *cl_type_setup(const struct lu_env *env, struct lu_site *site,
3148 struct lu_device_type *ldt,
3149 struct lu_device *next);
3152 #endif /* _LINUX_CL_OBJECT_H */