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36 #ifndef _LUSTRE_CL_OBJECT_H
37 #define _LUSTRE_CL_OBJECT_H
39 /** \defgroup clio clio
41 * Client objects implement io operations and cache pages.
43 * Examples: lov and osc are implementations of cl interface.
45 * Big Theory Statement.
49 * Client implementation is based on the following data-types:
55 * - cl_lock represents an extent lock on an object.
57 * - cl_io represents high-level i/o activity such as whole read/write
58 * system call, or write-out of pages from under the lock being
59 * canceled. cl_io has sub-ios that can be stopped and resumed
60 * independently, thus achieving high degree of transfer
61 * parallelism. Single cl_io can be advanced forward by
62 * the multiple threads (although in the most usual case of
63 * read/write system call it is associated with the single user
64 * thread, that issued the system call).
66 * - cl_req represents a collection of pages for a transfer. cl_req is
67 * constructed by req-forming engine that tries to saturate
68 * transport with large and continuous transfers.
72 * - to avoid confusion high-level I/O operation like read or write system
73 * call is referred to as "an io", whereas low-level I/O operation, like
74 * RPC, is referred to as "a transfer"
76 * - "generic code" means generic (not file system specific) code in the
77 * hosting environment. "cl-code" means code (mostly in cl_*.c files) that
78 * is not layer specific.
84 * - cl_object_header::coh_page_guard
85 * - cl_object_header::coh_lock_guard
88 * See the top comment in cl_object.c for the description of overall locking and
89 * reference-counting design.
91 * See comments below for the description of i/o, page, and dlm-locking
98 * super-class definitions.
100 #include <libcfs/libcfs.h>
101 #include <lu_object.h>
102 #include <linux/mutex.h>
103 #include <linux/radix-tree.h>
108 struct cl_device_operations;
111 struct cl_object_page_operations;
112 struct cl_object_lock_operations;
115 struct cl_page_slice;
117 struct cl_lock_slice;
119 struct cl_lock_operations;
120 struct cl_page_operations;
129 * Operations for each data device in the client stack.
131 * \see vvp_cl_ops, lov_cl_ops, lovsub_cl_ops, osc_cl_ops
133 struct cl_device_operations {
135 * Initialize cl_req. This method is called top-to-bottom on all
136 * devices in the stack to get them a chance to allocate layer-private
137 * data, and to attach them to the cl_req by calling
138 * cl_req_slice_add().
140 * \see osc_req_init(), lov_req_init(), lovsub_req_init()
141 * \see ccc_req_init()
143 int (*cdo_req_init)(const struct lu_env *env, struct cl_device *dev,
148 * Device in the client stack.
150 * \see ccc_device, lov_device, lovsub_device, osc_device
154 struct lu_device cd_lu_dev;
155 /** Per-layer operation vector. */
156 const struct cl_device_operations *cd_ops;
159 /** \addtogroup cl_object cl_object
162 * "Data attributes" of cl_object. Data attributes can be updated
163 * independently for a sub-object, and top-object's attributes are calculated
164 * from sub-objects' ones.
167 /** Object size, in bytes */
170 * Known minimal size, in bytes.
172 * This is only valid when at least one DLM lock is held.
175 /** Modification time. Measured in seconds since epoch. */
177 /** Access time. Measured in seconds since epoch. */
179 /** Change time. Measured in seconds since epoch. */
182 * Blocks allocated to this cl_object on the server file system.
184 * \todo XXX An interface for block size is needed.
188 * User identifier for quota purposes.
192 * Group identifier for quota purposes.
196 /* nlink of the directory */
201 * Fields in cl_attr that are being set.
215 * Sub-class of lu_object with methods common for objects on the client
218 * cl_object: represents a regular file system object, both a file and a
219 * stripe. cl_object is based on lu_object: it is identified by a fid,
220 * layered, cached, hashed, and lrued. Important distinction with the server
221 * side, where md_object and dt_object are used, is that cl_object "fans out"
222 * at the lov/sns level: depending on the file layout, single file is
223 * represented as a set of "sub-objects" (stripes). At the implementation
224 * level, struct lov_object contains an array of cl_objects. Each sub-object
225 * is a full-fledged cl_object, having its fid, living in the lru and hash
228 * This leads to the next important difference with the server side: on the
229 * client, it's quite usual to have objects with the different sequence of
230 * layers. For example, typical top-object is composed of the following
236 * whereas its sub-objects are composed of
241 * layers. Here "lovsub" is a mostly dummy layer, whose purpose is to keep
242 * track of the object-subobject relationship.
244 * Sub-objects are not cached independently: when top-object is about to
245 * be discarded from the memory, all its sub-objects are torn-down and
248 * \see ccc_object, lov_object, lovsub_object, osc_object
252 struct lu_object co_lu;
253 /** per-object-layer operations */
254 const struct cl_object_operations *co_ops;
255 /** offset of page slice in cl_page buffer */
260 * Description of the client object configuration. This is used for the
261 * creation of a new client object that is identified by a more state than
264 struct cl_object_conf {
266 struct lu_object_conf coc_lu;
269 * Object layout. This is consumed by lov.
271 struct lustre_md *coc_md;
273 * Description of particular stripe location in the
274 * cluster. This is consumed by osc.
276 struct lov_oinfo *coc_oinfo;
279 * VFS inode. This is consumed by vvp.
281 struct inode *coc_inode;
283 * Layout lock handle.
285 struct ldlm_lock *coc_lock;
287 * Operation to handle layout, OBJECT_CONF_XYZ.
293 /** configure layout, set up a new stripe, must be called while
294 * holding layout lock. */
296 /** invalidate the current stripe configuration due to losing
298 OBJECT_CONF_INVALIDATE = 1,
299 /** wait for old layout to go away so that new layout can be
305 * Operations implemented for each cl object layer.
307 * \see vvp_ops, lov_ops, lovsub_ops, osc_ops
309 struct cl_object_operations {
311 * Initialize page slice for this layer. Called top-to-bottom through
312 * every object layer when a new cl_page is instantiated. Layer
313 * keeping private per-page data, or requiring its own page operations
314 * vector should allocate these data here, and attach then to the page
315 * by calling cl_page_slice_add(). \a vmpage is locked (in the VM
318 * \retval NULL success.
320 * \retval ERR_PTR(errno) failure code.
322 * \retval valid-pointer pointer to already existing referenced page
323 * to be used instead of newly created.
325 int (*coo_page_init)(const struct lu_env *env, struct cl_object *obj,
326 struct cl_page *page, pgoff_t index);
328 * Initialize lock slice for this layer. Called top-to-bottom through
329 * every object layer when a new cl_lock is instantiated. Layer
330 * keeping private per-lock data, or requiring its own lock operations
331 * vector should allocate these data here, and attach then to the lock
332 * by calling cl_lock_slice_add(). Mandatory.
334 int (*coo_lock_init)(const struct lu_env *env,
335 struct cl_object *obj, struct cl_lock *lock,
336 const struct cl_io *io);
338 * Initialize io state for a given layer.
340 * called top-to-bottom once per io existence to initialize io
341 * state. If layer wants to keep some state for this type of io, it
342 * has to embed struct cl_io_slice in lu_env::le_ses, and register
343 * slice with cl_io_slice_add(). It is guaranteed that all threads
344 * participating in this io share the same session.
346 int (*coo_io_init)(const struct lu_env *env,
347 struct cl_object *obj, struct cl_io *io);
349 * Fill portion of \a attr that this layer controls. This method is
350 * called top-to-bottom through all object layers.
352 * \pre cl_object_header::coh_attr_guard of the top-object is locked.
354 * \return 0: to continue
355 * \return +ve: to stop iterating through layers (but 0 is returned
356 * from enclosing cl_object_attr_get())
357 * \return -ve: to signal error
359 int (*coo_attr_get)(const struct lu_env *env, struct cl_object *obj,
360 struct cl_attr *attr);
364 * \a valid is a bitmask composed from enum #cl_attr_valid, and
365 * indicating what attributes are to be set.
367 * \pre cl_object_header::coh_attr_guard of the top-object is locked.
369 * \return the same convention as for
370 * cl_object_operations::coo_attr_get() is used.
372 int (*coo_attr_set)(const struct lu_env *env, struct cl_object *obj,
373 const struct cl_attr *attr, unsigned valid);
375 * Update object configuration. Called top-to-bottom to modify object
378 * XXX error conditions and handling.
380 int (*coo_conf_set)(const struct lu_env *env, struct cl_object *obj,
381 const struct cl_object_conf *conf);
383 * Glimpse ast. Executed when glimpse ast arrives for a lock on this
384 * object. Layers are supposed to fill parts of \a lvb that will be
385 * shipped to the glimpse originator as a glimpse result.
387 * \see ccc_object_glimpse(), lovsub_object_glimpse(),
388 * \see osc_object_glimpse()
390 int (*coo_glimpse)(const struct lu_env *env,
391 const struct cl_object *obj, struct ost_lvb *lvb);
393 * Object prune method. Called when the layout is going to change on
394 * this object, therefore each layer has to clean up their cache,
395 * mainly pages and locks.
397 int (*coo_prune)(const struct lu_env *env, struct cl_object *obj);
401 * Extended header for client object.
403 struct cl_object_header {
404 /** Standard lu_object_header. cl_object::co_lu::lo_header points
406 struct lu_object_header coh_lu;
408 * \todo XXX move locks below to the separate cache-lines, they are
409 * mostly useless otherwise.
412 /** Lock protecting lock list. */
413 spinlock_t coh_lock_guard;
415 /** List of cl_lock's granted for this object. */
416 struct list_head coh_locks;
419 * Parent object. It is assumed that an object has a well-defined
420 * parent, but not a well-defined child (there may be multiple
421 * sub-objects, for the same top-object). cl_object_header::coh_parent
422 * field allows certain code to be written generically, without
423 * limiting possible cl_object layouts unduly.
425 struct cl_object_header *coh_parent;
427 * Protects consistency between cl_attr of parent object and
428 * attributes of sub-objects, that the former is calculated ("merged")
431 * \todo XXX this can be read/write lock if needed.
433 spinlock_t coh_attr_guard;
435 * Size of cl_page + page slices
437 unsigned short coh_page_bufsize;
439 * Number of objects above this one: 0 for a top-object, 1 for its
442 unsigned char coh_nesting;
446 * Helper macro: iterate over all layers of the object \a obj, assigning every
447 * layer top-to-bottom to \a slice.
449 #define cl_object_for_each(slice, obj) \
450 list_for_each_entry((slice), \
451 &(obj)->co_lu.lo_header->loh_layers,\
455 * Helper macro: iterate over all layers of the object \a obj, assigning every
456 * layer bottom-to-top to \a slice.
458 #define cl_object_for_each_reverse(slice, obj) \
459 list_for_each_entry_reverse((slice), \
460 &(obj)->co_lu.lo_header->loh_layers,\
464 #define CL_PAGE_EOF ((pgoff_t)~0ull)
466 /** \addtogroup cl_page cl_page
470 * Layered client page.
472 * cl_page: represents a portion of a file, cached in the memory. All pages
473 * of the given file are of the same size, and are kept in the radix tree
474 * hanging off the cl_object. cl_page doesn't fan out, but as sub-objects
475 * of the top-level file object are first class cl_objects, they have their
476 * own radix trees of pages and hence page is implemented as a sequence of
477 * struct cl_pages's, linked into double-linked list through
478 * cl_page::cp_parent and cl_page::cp_child pointers, each residing in the
479 * corresponding radix tree at the corresponding logical offset.
481 * cl_page is associated with VM page of the hosting environment (struct
482 * page in Linux kernel, for example), struct page. It is assumed, that this
483 * association is implemented by one of cl_page layers (top layer in the
484 * current design) that
486 * - intercepts per-VM-page call-backs made by the environment (e.g.,
489 * - translates state (page flag bits) and locking between lustre and
492 * The association between cl_page and struct page is immutable and
493 * established when cl_page is created.
495 * cl_page can be "owned" by a particular cl_io (see below), guaranteeing
496 * this io an exclusive access to this page w.r.t. other io attempts and
497 * various events changing page state (such as transfer completion, or
498 * eviction of the page from the memory). Note, that in general cl_io
499 * cannot be identified with a particular thread, and page ownership is not
500 * exactly equal to the current thread holding a lock on the page. Layer
501 * implementing association between cl_page and struct page has to implement
502 * ownership on top of available synchronization mechanisms.
504 * While lustre client maintains the notion of an page ownership by io,
505 * hosting MM/VM usually has its own page concurrency control
506 * mechanisms. For example, in Linux, page access is synchronized by the
507 * per-page PG_locked bit-lock, and generic kernel code (generic_file_*())
508 * takes care to acquire and release such locks as necessary around the
509 * calls to the file system methods (->readpage(), ->prepare_write(),
510 * ->commit_write(), etc.). This leads to the situation when there are two
511 * different ways to own a page in the client:
513 * - client code explicitly and voluntary owns the page (cl_page_own());
515 * - VM locks a page and then calls the client, that has "to assume"
516 * the ownership from the VM (cl_page_assume()).
518 * Dual methods to release ownership are cl_page_disown() and
519 * cl_page_unassume().
521 * cl_page is reference counted (cl_page::cp_ref). When reference counter
522 * drops to 0, the page is returned to the cache, unless it is in
523 * cl_page_state::CPS_FREEING state, in which case it is immediately
526 * The general logic guaranteeing the absence of "existential races" for
527 * pages is the following:
529 * - there are fixed known ways for a thread to obtain a new reference
532 * - by doing a lookup in the cl_object radix tree, protected by the
535 * - by starting from VM-locked struct page and following some
536 * hosting environment method (e.g., following ->private pointer in
537 * the case of Linux kernel), see cl_vmpage_page();
539 * - when the page enters cl_page_state::CPS_FREEING state, all these
540 * ways are severed with the proper synchronization
541 * (cl_page_delete());
543 * - entry into cl_page_state::CPS_FREEING is serialized by the VM page
546 * - no new references to the page in cl_page_state::CPS_FREEING state
547 * are allowed (checked in cl_page_get()).
549 * Together this guarantees that when last reference to a
550 * cl_page_state::CPS_FREEING page is released, it is safe to destroy the
551 * page, as neither references to it can be acquired at that point, nor
554 * cl_page is a state machine. States are enumerated in enum
555 * cl_page_state. Possible state transitions are enumerated in
556 * cl_page_state_set(). State transition process (i.e., actual changing of
557 * cl_page::cp_state field) is protected by the lock on the underlying VM
560 * Linux Kernel implementation.
562 * Binding between cl_page and struct page (which is a typedef for
563 * struct page) is implemented in the vvp layer. cl_page is attached to the
564 * ->private pointer of the struct page, together with the setting of
565 * PG_private bit in page->flags, and acquiring additional reference on the
566 * struct page (much like struct buffer_head, or any similar file system
567 * private data structures).
569 * PG_locked lock is used to implement both ownership and transfer
570 * synchronization, that is, page is VM-locked in CPS_{OWNED,PAGE{IN,OUT}}
571 * states. No additional references are acquired for the duration of the
574 * \warning *THIS IS NOT* the behavior expected by the Linux kernel, where
575 * write-out is "protected" by the special PG_writeback bit.
579 * States of cl_page. cl_page.c assumes particular order here.
581 * The page state machine is rather crude, as it doesn't recognize finer page
582 * states like "dirty" or "up to date". This is because such states are not
583 * always well defined for the whole stack (see, for example, the
584 * implementation of the read-ahead, that hides page up-to-dateness to track
585 * cache hits accurately). Such sub-states are maintained by the layers that
586 * are interested in them.
590 * Page is in the cache, un-owned. Page leaves cached state in the
593 * - [cl_page_state::CPS_OWNED] io comes across the page and
596 * - [cl_page_state::CPS_PAGEOUT] page is dirty, the
597 * req-formation engine decides that it wants to include this page
598 * into an cl_req being constructed, and yanks it from the cache;
600 * - [cl_page_state::CPS_FREEING] VM callback is executed to
601 * evict the page form the memory;
603 * \invariant cl_page::cp_owner == NULL && cl_page::cp_req == NULL
607 * Page is exclusively owned by some cl_io. Page may end up in this
608 * state as a result of
610 * - io creating new page and immediately owning it;
612 * - [cl_page_state::CPS_CACHED] io finding existing cached page
615 * - [cl_page_state::CPS_OWNED] io finding existing owned page
616 * and waiting for owner to release the page;
618 * Page leaves owned state in the following cases:
620 * - [cl_page_state::CPS_CACHED] io decides to leave the page in
621 * the cache, doing nothing;
623 * - [cl_page_state::CPS_PAGEIN] io starts read transfer for
626 * - [cl_page_state::CPS_PAGEOUT] io starts immediate write
627 * transfer for this page;
629 * - [cl_page_state::CPS_FREEING] io decides to destroy this
630 * page (e.g., as part of truncate or extent lock cancellation).
632 * \invariant cl_page::cp_owner != NULL && cl_page::cp_req == NULL
636 * Page is being written out, as a part of a transfer. This state is
637 * entered when req-formation logic decided that it wants this page to
638 * be sent through the wire _now_. Specifically, it means that once
639 * this state is achieved, transfer completion handler (with either
640 * success or failure indication) is guaranteed to be executed against
641 * this page independently of any locks and any scheduling decisions
642 * made by the hosting environment (that effectively means that the
643 * page is never put into cl_page_state::CPS_PAGEOUT state "in
644 * advance". This property is mentioned, because it is important when
645 * reasoning about possible dead-locks in the system). The page can
646 * enter this state as a result of
648 * - [cl_page_state::CPS_OWNED] an io requesting an immediate
649 * write-out of this page, or
651 * - [cl_page_state::CPS_CACHED] req-forming engine deciding
652 * that it has enough dirty pages cached to issue a "good"
655 * The page leaves cl_page_state::CPS_PAGEOUT state when the transfer
656 * is completed---it is moved into cl_page_state::CPS_CACHED state.
658 * Underlying VM page is locked for the duration of transfer.
660 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL
664 * Page is being read in, as a part of a transfer. This is quite
665 * similar to the cl_page_state::CPS_PAGEOUT state, except that
666 * read-in is always "immediate"---there is no such thing a sudden
667 * construction of read cl_req from cached, presumably not up to date,
670 * Underlying VM page is locked for the duration of transfer.
672 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL
676 * Page is being destroyed. This state is entered when client decides
677 * that page has to be deleted from its host object, as, e.g., a part
680 * Once this state is reached, there is no way to escape it.
682 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req == NULL
689 /** Host page, the page is from the host inode which the cl_page
693 /** Transient page, the transient cl_page is used to bind a cl_page
694 * to vmpage which is not belonging to the same object of cl_page.
695 * it is used in DirectIO, lockless IO and liblustre. */
700 * Fields are protected by the lock on struct page, except for atomics and
703 * \invariant Data type invariants are in cl_page_invariant(). Basically:
704 * cl_page::cp_parent and cl_page::cp_child are a well-formed double-linked
705 * list, consistent with the parent/child pointers in the cl_page::cp_obj and
706 * cl_page::cp_owner (when set).
709 /** Reference counter. */
711 /** Transfer error. */
713 /** An object this page is a part of. Immutable after creation. */
714 struct cl_object *cp_obj;
716 struct page *cp_vmpage;
717 /** Linkage of pages within group. Pages must be owned */
718 struct list_head cp_batch;
719 /** List of slices. Immutable after creation. */
720 struct list_head cp_layers;
721 /** Linkage of pages within cl_req. */
722 struct list_head cp_flight;
724 * Page state. This field is const to avoid accidental update, it is
725 * modified only internally within cl_page.c. Protected by a VM lock.
727 const enum cl_page_state cp_state;
729 * Page type. Only CPT_TRANSIENT is used so far. Immutable after
732 enum cl_page_type cp_type;
735 * Owning IO in cl_page_state::CPS_OWNED state. Sub-page can be owned
736 * by sub-io. Protected by a VM lock.
738 struct cl_io *cp_owner;
740 * Owning IO request in cl_page_state::CPS_PAGEOUT and
741 * cl_page_state::CPS_PAGEIN states. This field is maintained only in
742 * the top-level pages. Protected by a VM lock.
744 struct cl_req *cp_req;
745 /** List of references to this page, for debugging. */
746 struct lu_ref cp_reference;
747 /** Link to an object, for debugging. */
748 struct lu_ref_link cp_obj_ref;
749 /** Link to a queue, for debugging. */
750 struct lu_ref_link cp_queue_ref;
751 /** Assigned if doing a sync_io */
752 struct cl_sync_io *cp_sync_io;
756 * Per-layer part of cl_page.
758 * \see ccc_page, lov_page, osc_page
760 struct cl_page_slice {
761 struct cl_page *cpl_page;
764 * Object slice corresponding to this page slice. Immutable after
767 struct cl_object *cpl_obj;
768 const struct cl_page_operations *cpl_ops;
769 /** Linkage into cl_page::cp_layers. Immutable after creation. */
770 struct list_head cpl_linkage;
774 * Lock mode. For the client extent locks.
776 * \warning: cl_lock_mode_match() assumes particular ordering here.
781 * Mode of a lock that protects no data, and exists only as a
782 * placeholder. This is used for `glimpse' requests. A phantom lock
783 * might get promoted to real lock at some point.
793 * Requested transfer type.
803 * Per-layer page operations.
805 * Methods taking an \a io argument are for the activity happening in the
806 * context of given \a io. Page is assumed to be owned by that io, except for
807 * the obvious cases (like cl_page_operations::cpo_own()).
809 * \see vvp_page_ops, lov_page_ops, osc_page_ops
811 struct cl_page_operations {
813 * cl_page<->struct page methods. Only one layer in the stack has to
814 * implement these. Current code assumes that this functionality is
815 * provided by the topmost layer, see cl_page_disown0() as an example.
819 * Called when \a io acquires this page into the exclusive
820 * ownership. When this method returns, it is guaranteed that the is
821 * not owned by other io, and no transfer is going on against
825 * \see vvp_page_own(), lov_page_own()
827 int (*cpo_own)(const struct lu_env *env,
828 const struct cl_page_slice *slice,
829 struct cl_io *io, int nonblock);
830 /** Called when ownership it yielded. Optional.
832 * \see cl_page_disown()
833 * \see vvp_page_disown()
835 void (*cpo_disown)(const struct lu_env *env,
836 const struct cl_page_slice *slice, struct cl_io *io);
838 * Called for a page that is already "owned" by \a io from VM point of
841 * \see cl_page_assume()
842 * \see vvp_page_assume(), lov_page_assume()
844 void (*cpo_assume)(const struct lu_env *env,
845 const struct cl_page_slice *slice, struct cl_io *io);
846 /** Dual to cl_page_operations::cpo_assume(). Optional. Called
847 * bottom-to-top when IO releases a page without actually unlocking
850 * \see cl_page_unassume()
851 * \see vvp_page_unassume()
853 void (*cpo_unassume)(const struct lu_env *env,
854 const struct cl_page_slice *slice,
857 * Announces whether the page contains valid data or not by \a uptodate.
859 * \see cl_page_export()
860 * \see vvp_page_export()
862 void (*cpo_export)(const struct lu_env *env,
863 const struct cl_page_slice *slice, int uptodate);
865 * Checks whether underlying VM page is locked (in the suitable
866 * sense). Used for assertions.
868 * \retval -EBUSY: page is protected by a lock of a given mode;
869 * \retval -ENODATA: page is not protected by a lock;
870 * \retval 0: this layer cannot decide. (Should never happen.)
872 int (*cpo_is_vmlocked)(const struct lu_env *env,
873 const struct cl_page_slice *slice);
879 * Called when page is truncated from the object. Optional.
881 * \see cl_page_discard()
882 * \see vvp_page_discard(), osc_page_discard()
884 void (*cpo_discard)(const struct lu_env *env,
885 const struct cl_page_slice *slice,
888 * Called when page is removed from the cache, and is about to being
889 * destroyed. Optional.
891 * \see cl_page_delete()
892 * \see vvp_page_delete(), osc_page_delete()
894 void (*cpo_delete)(const struct lu_env *env,
895 const struct cl_page_slice *slice);
896 /** Destructor. Frees resources and slice itself. */
897 void (*cpo_fini)(const struct lu_env *env,
898 struct cl_page_slice *slice);
901 * Checks whether the page is protected by a cl_lock. This is a
902 * per-layer method, because certain layers have ways to check for the
903 * lock much more efficiently than through the generic locks scan, or
904 * implement locking mechanisms separate from cl_lock, e.g.,
905 * LL_FILE_GROUP_LOCKED in vvp. If \a pending is true, check for locks
906 * being canceled, or scheduled for cancellation as soon as the last
907 * user goes away, too.
909 * \retval -EBUSY: page is protected by a lock of a given mode;
910 * \retval -ENODATA: page is not protected by a lock;
911 * \retval 0: this layer cannot decide.
913 * \see cl_page_is_under_lock()
915 int (*cpo_is_under_lock)(const struct lu_env *env,
916 const struct cl_page_slice *slice,
917 struct cl_io *io, pgoff_t *max);
920 * Optional debugging helper. Prints given page slice.
922 * \see cl_page_print()
924 int (*cpo_print)(const struct lu_env *env,
925 const struct cl_page_slice *slice,
926 void *cookie, lu_printer_t p);
930 * Transfer methods. See comment on cl_req for a description of
931 * transfer formation and life-cycle.
936 * Request type dependent vector of operations.
938 * Transfer operations depend on transfer mode (cl_req_type). To avoid
939 * passing transfer mode to each and every of these methods, and to
940 * avoid branching on request type inside of the methods, separate
941 * methods for cl_req_type:CRT_READ and cl_req_type:CRT_WRITE are
942 * provided. That is, method invocation usually looks like
944 * slice->cp_ops.io[req->crq_type].cpo_method(env, slice, ...);
948 * Called when a page is submitted for a transfer as a part of
951 * \return 0 : page is eligible for submission;
952 * \return -EALREADY : skip this page;
953 * \return -ve : error.
955 * \see cl_page_prep()
957 int (*cpo_prep)(const struct lu_env *env,
958 const struct cl_page_slice *slice,
961 * Completion handler. This is guaranteed to be eventually
962 * fired after cl_page_operations::cpo_prep() or
963 * cl_page_operations::cpo_make_ready() call.
965 * This method can be called in a non-blocking context. It is
966 * guaranteed however, that the page involved and its object
967 * are pinned in memory (and, hence, calling cl_page_put() is
970 * \see cl_page_completion()
972 void (*cpo_completion)(const struct lu_env *env,
973 const struct cl_page_slice *slice,
976 * Called when cached page is about to be added to the
977 * cl_req as a part of req formation.
979 * \return 0 : proceed with this page;
980 * \return -EAGAIN : skip this page;
981 * \return -ve : error.
983 * \see cl_page_make_ready()
985 int (*cpo_make_ready)(const struct lu_env *env,
986 const struct cl_page_slice *slice);
989 * Tell transfer engine that only [to, from] part of a page should be
992 * This is used for immediate transfers.
994 * \todo XXX this is not very good interface. It would be much better
995 * if all transfer parameters were supplied as arguments to
996 * cl_io_operations::cio_submit() call, but it is not clear how to do
997 * this for page queues.
999 * \see cl_page_clip()
1001 void (*cpo_clip)(const struct lu_env *env,
1002 const struct cl_page_slice *slice,
1005 * \pre the page was queued for transferring.
1006 * \post page is removed from client's pending list, or -EBUSY
1007 * is returned if it has already been in transferring.
1009 * This is one of seldom page operation which is:
1010 * 0. called from top level;
1011 * 1. don't have vmpage locked;
1012 * 2. every layer should synchronize execution of its ->cpo_cancel()
1013 * with completion handlers. Osc uses client obd lock for this
1014 * purpose. Based on there is no vvp_page_cancel and
1015 * lov_page_cancel(), cpo_cancel is defacto protected by client lock.
1017 * \see osc_page_cancel().
1019 int (*cpo_cancel)(const struct lu_env *env,
1020 const struct cl_page_slice *slice);
1022 * Write out a page by kernel. This is only called by ll_writepage
1025 * \see cl_page_flush()
1027 int (*cpo_flush)(const struct lu_env *env,
1028 const struct cl_page_slice *slice,
1034 * Helper macro, dumping detailed information about \a page into a log.
1036 #define CL_PAGE_DEBUG(mask, env, page, format, ...) \
1038 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1039 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1040 cl_page_print(env, &msgdata, lu_cdebug_printer, page); \
1041 CDEBUG(mask, format , ## __VA_ARGS__); \
1046 * Helper macro, dumping shorter information about \a page into a log.
1048 #define CL_PAGE_HEADER(mask, env, page, format, ...) \
1050 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1051 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1052 cl_page_header_print(env, &msgdata, lu_cdebug_printer, page); \
1053 CDEBUG(mask, format , ## __VA_ARGS__); \
1057 static inline struct page *cl_page_vmpage(const struct cl_page *page)
1059 LASSERT(page->cp_vmpage != NULL);
1060 return page->cp_vmpage;
1064 * Check if a cl_page is in use.
1066 * Client cache holds a refcount, this refcount will be dropped when
1067 * the page is taken out of cache, see vvp_page_delete().
1069 static inline bool __page_in_use(const struct cl_page *page, int refc)
1071 return (atomic_read(&page->cp_ref) > refc + 1);
1075 * Caller itself holds a refcount of cl_page.
1077 #define cl_page_in_use(pg) __page_in_use(pg, 1)
1079 * Caller doesn't hold a refcount.
1081 #define cl_page_in_use_noref(pg) __page_in_use(pg, 0)
1085 /** \addtogroup cl_lock cl_lock
1089 * Extent locking on the client.
1093 * The locking model of the new client code is built around
1097 * data-type representing an extent lock on a regular file. cl_lock is a
1098 * layered object (much like cl_object and cl_page), it consists of a header
1099 * (struct cl_lock) and a list of layers (struct cl_lock_slice), linked to
1100 * cl_lock::cll_layers list through cl_lock_slice::cls_linkage.
1102 * All locks for a given object are linked into cl_object_header::coh_locks
1103 * list (protected by cl_object_header::coh_lock_guard spin-lock) through
1104 * cl_lock::cll_linkage. Currently this list is not sorted in any way. We can
1105 * sort it in starting lock offset, or use altogether different data structure
1108 * Typical cl_lock consists of the two layers:
1110 * - vvp_lock (vvp specific data), and
1111 * - lov_lock (lov specific data).
1113 * lov_lock contains an array of sub-locks. Each of these sub-locks is a
1114 * normal cl_lock: it has a header (struct cl_lock) and a list of layers:
1116 * - lovsub_lock, and
1119 * Each sub-lock is associated with a cl_object (representing stripe
1120 * sub-object or the file to which top-level cl_lock is associated to), and is
1121 * linked into that cl_object::coh_locks. In this respect cl_lock is similar to
1122 * cl_object (that at lov layer also fans out into multiple sub-objects), and
1123 * is different from cl_page, that doesn't fan out (there is usually exactly
1124 * one osc_page for every vvp_page). We shall call vvp-lov portion of the lock
1125 * a "top-lock" and its lovsub-osc portion a "sub-lock".
1129 * cl_lock is reference counted. When reference counter drops to 0, lock is
1130 * placed in the cache, except when lock is in CLS_FREEING state. CLS_FREEING
1131 * lock is destroyed when last reference is released. Referencing between
1132 * top-lock and its sub-locks is described in the lov documentation module.
1136 * Also, cl_lock is a state machine. This requires some clarification. One of
1137 * the goals of client IO re-write was to make IO path non-blocking, or at
1138 * least to make it easier to make it non-blocking in the future. Here
1139 * `non-blocking' means that when a system call (read, write, truncate)
1140 * reaches a situation where it has to wait for a communication with the
1141 * server, it should --instead of waiting-- remember its current state and
1142 * switch to some other work. E.g,. instead of waiting for a lock enqueue,
1143 * client should proceed doing IO on the next stripe, etc. Obviously this is
1144 * rather radical redesign, and it is not planned to be fully implemented at
1145 * this time, instead we are putting some infrastructure in place, that would
1146 * make it easier to do asynchronous non-blocking IO easier in the
1147 * future. Specifically, where old locking code goes to sleep (waiting for
1148 * enqueue, for example), new code returns cl_lock_transition::CLO_WAIT. When
1149 * enqueue reply comes, its completion handler signals that lock state-machine
1150 * is ready to transit to the next state. There is some generic code in
1151 * cl_lock.c that sleeps, waiting for these signals. As a result, for users of
1152 * this cl_lock.c code, it looks like locking is done in normal blocking
1153 * fashion, and it the same time it is possible to switch to the non-blocking
1154 * locking (simply by returning cl_lock_transition::CLO_WAIT from cl_lock.c
1157 * For a description of state machine states and transitions see enum
1160 * There are two ways to restrict a set of states which lock might move to:
1162 * - placing a "hold" on a lock guarantees that lock will not be moved
1163 * into cl_lock_state::CLS_FREEING state until hold is released. Hold
1164 * can be only acquired on a lock that is not in
1165 * cl_lock_state::CLS_FREEING. All holds on a lock are counted in
1166 * cl_lock::cll_holds. Hold protects lock from cancellation and
1167 * destruction. Requests to cancel and destroy a lock on hold will be
1168 * recorded, but only honored when last hold on a lock is released;
1170 * - placing a "user" on a lock guarantees that lock will not leave
1171 * cl_lock_state::CLS_NEW, cl_lock_state::CLS_QUEUING,
1172 * cl_lock_state::CLS_ENQUEUED and cl_lock_state::CLS_HELD set of
1173 * states, once it enters this set. That is, if a user is added onto a
1174 * lock in a state not from this set, it doesn't immediately enforce
1175 * lock to move to this set, but once lock enters this set it will
1176 * remain there until all users are removed. Lock users are counted in
1177 * cl_lock::cll_users.
1179 * User is used to assure that lock is not canceled or destroyed while
1180 * it is being enqueued, or actively used by some IO.
1182 * Currently, a user always comes with a hold (cl_lock_invariant()
1183 * checks that a number of holds is not less than a number of users).
1187 * This is how lock state-machine operates. struct cl_lock contains a mutex
1188 * cl_lock::cll_guard that protects struct fields.
1190 * - mutex is taken, and cl_lock::cll_state is examined.
1192 * - for every state there are possible target states where lock can move
1193 * into. They are tried in order. Attempts to move into next state are
1194 * done by _try() functions in cl_lock.c:cl_{enqueue,unlock,wait}_try().
1196 * - if the transition can be performed immediately, state is changed,
1197 * and mutex is released.
1199 * - if the transition requires blocking, _try() function returns
1200 * cl_lock_transition::CLO_WAIT. Caller unlocks mutex and goes to
1201 * sleep, waiting for possibility of lock state change. It is woken
1202 * up when some event occurs, that makes lock state change possible
1203 * (e.g., the reception of the reply from the server), and repeats
1206 * Top-lock and sub-lock has separate mutexes and the latter has to be taken
1207 * first to avoid dead-lock.
1209 * To see an example of interaction of all these issues, take a look at the
1210 * lov_cl.c:lov_lock_enqueue() function. It is called as a part of
1211 * cl_enqueue_try(), and tries to advance top-lock to ENQUEUED state, by
1212 * advancing state-machines of its sub-locks (lov_lock_enqueue_one()). Note
1213 * also, that it uses trylock to grab sub-lock mutex to avoid dead-lock. It
1214 * also has to handle CEF_ASYNC enqueue, when sub-locks enqueues have to be
1215 * done in parallel, rather than one after another (this is used for glimpse
1216 * locks, that cannot dead-lock).
1218 * INTERFACE AND USAGE
1220 * struct cl_lock_operations provide a number of call-backs that are invoked
1221 * when events of interest occurs. Layers can intercept and handle glimpse,
1222 * blocking, cancel ASTs and a reception of the reply from the server.
1224 * One important difference with the old client locking model is that new
1225 * client has a representation for the top-lock, whereas in the old code only
1226 * sub-locks existed as real data structures and file-level locks are
1227 * represented by "request sets" that are created and destroyed on each and
1228 * every lock creation.
1230 * Top-locks are cached, and can be found in the cache by the system calls. It
1231 * is possible that top-lock is in cache, but some of its sub-locks were
1232 * canceled and destroyed. In that case top-lock has to be enqueued again
1233 * before it can be used.
1235 * Overall process of the locking during IO operation is as following:
1237 * - once parameters for IO are setup in cl_io, cl_io_operations::cio_lock()
1238 * is called on each layer. Responsibility of this method is to add locks,
1239 * needed by a given layer into cl_io.ci_lockset.
1241 * - once locks for all layers were collected, they are sorted to avoid
1242 * dead-locks (cl_io_locks_sort()), and enqueued.
1244 * - when all locks are acquired, IO is performed;
1246 * - locks are released into cache.
1248 * Striping introduces major additional complexity into locking. The
1249 * fundamental problem is that it is generally unsafe to actively use (hold)
1250 * two locks on the different OST servers at the same time, as this introduces
1251 * inter-server dependency and can lead to cascading evictions.
1253 * Basic solution is to sub-divide large read/write IOs into smaller pieces so
1254 * that no multi-stripe locks are taken (note that this design abandons POSIX
1255 * read/write semantics). Such pieces ideally can be executed concurrently. At
1256 * the same time, certain types of IO cannot be sub-divived, without
1257 * sacrificing correctness. This includes:
1259 * - O_APPEND write, where [0, EOF] lock has to be taken, to guarantee
1262 * - ftruncate(fd, offset), where [offset, EOF] lock has to be taken.
1264 * Also, in the case of read(fd, buf, count) or write(fd, buf, count), where
1265 * buf is a part of memory mapped Lustre file, a lock or locks protecting buf
1266 * has to be held together with the usual lock on [offset, offset + count].
1268 * As multi-stripe locks have to be allowed, it makes sense to cache them, so
1269 * that, for example, a sequence of O_APPEND writes can proceed quickly
1270 * without going down to the individual stripes to do lock matching. On the
1271 * other hand, multi-stripe locks shouldn't be used by normal read/write
1272 * calls. To achieve this, every layer can implement ->clo_fits_into() method,
1273 * that is called by lock matching code (cl_lock_lookup()), and that can be
1274 * used to selectively disable matching of certain locks for certain IOs. For
1275 * exmaple, lov layer implements lov_lock_fits_into() that allow multi-stripe
1276 * locks to be matched only for truncates and O_APPEND writes.
1278 * Interaction with DLM
1280 * In the expected setup, cl_lock is ultimately backed up by a collection of
1281 * DLM locks (struct ldlm_lock). Association between cl_lock and DLM lock is
1282 * implemented in osc layer, that also matches DLM events (ASTs, cancellation,
1283 * etc.) into cl_lock_operation calls. See struct osc_lock for a more detailed
1284 * description of interaction with DLM.
1290 struct cl_lock_descr {
1291 /** Object this lock is granted for. */
1292 struct cl_object *cld_obj;
1293 /** Index of the first page protected by this lock. */
1295 /** Index of the last page (inclusive) protected by this lock. */
1297 /** Group ID, for group lock */
1300 enum cl_lock_mode cld_mode;
1302 * flags to enqueue lock. A combination of bit-flags from
1303 * enum cl_enq_flags.
1305 __u32 cld_enq_flags;
1308 #define DDESCR "%s(%d):[%lu, %lu]"
1309 #define PDESCR(descr) \
1310 cl_lock_mode_name((descr)->cld_mode), (descr)->cld_mode, \
1311 (descr)->cld_start, (descr)->cld_end
1313 const char *cl_lock_mode_name(const enum cl_lock_mode mode);
1316 * Lock state-machine states.
1321 * Possible state transitions:
1323 * +------------------>NEW
1325 * | | cl_enqueue_try()
1327 * | cl_unuse_try() V
1328 * | +--------------QUEUING (*)
1330 * | | | cl_enqueue_try()
1332 * | | cl_unuse_try() V
1333 * sub-lock | +-------------ENQUEUED (*)
1335 * | | | cl_wait_try()
1340 * | | HELD<---------+
1342 * | | | | cl_use_try()
1343 * | | cl_unuse_try() | |
1346 * | +------------>INTRANSIT (D) <--+
1348 * | cl_unuse_try() | | cached lock found
1349 * | | | cl_use_try()
1352 * +------------------CACHED---------+
1361 * In states marked with (*) transition to the same state (i.e., a loop
1362 * in the diagram) is possible.
1364 * (R) is the point where Receive call-back is invoked: it allows layers
1365 * to handle arrival of lock reply.
1367 * (C) is the point where Cancellation call-back is invoked.
1369 * (D) is the transit state which means the lock is changing.
1371 * Transition to FREEING state is possible from any other state in the
1372 * diagram in case of unrecoverable error.
1376 * These states are for individual cl_lock object. Top-lock and its sub-locks
1377 * can be in the different states. Another way to say this is that we have
1378 * nested state-machines.
1380 * Separate QUEUING and ENQUEUED states are needed to support non-blocking
1381 * operation for locks with multiple sub-locks. Imagine lock on a file F, that
1382 * intersects 3 stripes S0, S1, and S2. To enqueue F client has to send
1383 * enqueue to S0, wait for its completion, then send enqueue for S1, wait for
1384 * its completion and at last enqueue lock for S2, and wait for its
1385 * completion. In that case, top-lock is in QUEUING state while S0, S1 are
1386 * handled, and is in ENQUEUED state after enqueue to S2 has been sent (note
1387 * that in this case, sub-locks move from state to state, and top-lock remains
1388 * in the same state).
1390 enum cl_lock_state {
1392 * Lock that wasn't yet enqueued
1396 * Enqueue is in progress, blocking for some intermediate interaction
1397 * with the other side.
1401 * Lock is fully enqueued, waiting for server to reply when it is
1406 * Lock granted, actively used by some IO.
1410 * This state is used to mark the lock is being used, or unused.
1411 * We need this state because the lock may have several sublocks,
1412 * so it's impossible to have an atomic way to bring all sublocks
1413 * into CLS_HELD state at use case, or all sublocks to CLS_CACHED
1415 * If a thread is referring to a lock, and it sees the lock is in this
1416 * state, it must wait for the lock.
1417 * See state diagram for details.
1421 * Lock granted, not used.
1425 * Lock is being destroyed.
1431 enum cl_lock_flags {
1433 * lock has been cancelled. This flag is never cleared once set (by
1434 * cl_lock_cancel0()).
1436 CLF_CANCELLED = 1 << 0,
1437 /** cancellation is pending for this lock. */
1438 CLF_CANCELPEND = 1 << 1,
1439 /** destruction is pending for this lock. */
1440 CLF_DOOMED = 1 << 2,
1441 /** from enqueue RPC reply upcall. */
1442 CLF_FROM_UPCALL= 1 << 3,
1448 * Lock closure is a collection of locks (both top-locks and sub-locks) that
1449 * might be updated in a result of an operation on a certain lock (which lock
1450 * this is a closure of).
1452 * Closures are needed to guarantee dead-lock freedom in the presence of
1454 * - nested state-machines (top-lock state-machine composed of sub-lock
1455 * state-machines), and
1457 * - shared sub-locks.
1459 * Specifically, many operations, such as lock enqueue, wait, unlock,
1460 * etc. start from a top-lock, and then operate on a sub-locks of this
1461 * top-lock, holding a top-lock mutex. When sub-lock state changes as a result
1462 * of such operation, this change has to be propagated to all top-locks that
1463 * share this sub-lock. Obviously, no natural lock ordering (e.g.,
1464 * top-to-bottom or bottom-to-top) captures this scenario, so try-locking has
1465 * to be used. Lock closure systematizes this try-and-repeat logic.
1467 struct cl_lock_closure {
1469 * Lock that is mutexed when closure construction is started. When
1470 * closure in is `wait' mode (cl_lock_closure::clc_wait), mutex on
1471 * origin is released before waiting.
1473 struct cl_lock *clc_origin;
1475 * List of enclosed locks, so far. Locks are linked here through
1476 * cl_lock::cll_inclosure.
1478 struct list_head clc_list;
1480 * True iff closure is in a `wait' mode. This determines what
1481 * cl_lock_enclosure() does when a lock L to be added to the closure
1482 * is currently mutexed by some other thread.
1484 * If cl_lock_closure::clc_wait is not set, then closure construction
1485 * fails with CLO_REPEAT immediately.
1487 * In wait mode, cl_lock_enclosure() waits until next attempt to build
1488 * a closure might succeed. To this end it releases an origin mutex
1489 * (cl_lock_closure::clc_origin), that has to be the only lock mutex
1490 * owned by the current thread, and then waits on L mutex (by grabbing
1491 * it and immediately releasing), before returning CLO_REPEAT to the
1495 /** Number of locks in the closure. */
1500 * Layered client lock.
1503 /** Reference counter. */
1505 /** List of slices. Immutable after creation. */
1506 struct list_head cll_layers;
1508 * Linkage into cl_lock::cll_descr::cld_obj::coh_locks list. Protected
1509 * by cl_lock::cll_descr::cld_obj::coh_lock_guard.
1511 struct list_head cll_linkage;
1513 * Parameters of this lock. Protected by
1514 * cl_lock::cll_descr::cld_obj::coh_lock_guard nested within
1515 * cl_lock::cll_guard. Modified only on lock creation and in
1518 struct cl_lock_descr cll_descr;
1519 /** Protected by cl_lock::cll_guard. */
1520 enum cl_lock_state cll_state;
1521 /** signals state changes. */
1522 wait_queue_head_t cll_wq;
1524 * Recursive lock, most fields in cl_lock{} are protected by this.
1526 * Locking rules: this mutex is never held across network
1527 * communication, except when lock is being canceled.
1529 * Lock ordering: a mutex of a sub-lock is taken first, then a mutex
1530 * on a top-lock. Other direction is implemented through a
1531 * try-lock-repeat loop. Mutices of unrelated locks can be taken only
1534 * \see osc_lock_enqueue_wait(), lov_lock_cancel(), lov_sublock_wait().
1536 struct mutex cll_guard;
1537 struct task_struct *cll_guarder;
1541 * the owner for INTRANSIT state
1543 struct task_struct *cll_intransit_owner;
1546 * Number of holds on a lock. A hold prevents a lock from being
1547 * canceled and destroyed. Protected by cl_lock::cll_guard.
1549 * \see cl_lock_hold(), cl_lock_unhold(), cl_lock_release()
1553 * Number of lock users. Valid in cl_lock_state::CLS_HELD state
1554 * only. Lock user pins lock in CLS_HELD state. Protected by
1555 * cl_lock::cll_guard.
1557 * \see cl_wait(), cl_unuse().
1561 * Flag bit-mask. Values from enum cl_lock_flags. Updates are
1562 * protected by cl_lock::cll_guard.
1564 unsigned long cll_flags;
1566 * A linkage into a list of locks in a closure.
1568 * \see cl_lock_closure
1570 struct list_head cll_inclosure;
1572 * Confict lock at queuing time.
1574 struct cl_lock *cll_conflict;
1576 * A list of references to this lock, for debugging.
1578 struct lu_ref cll_reference;
1580 * A list of holds on this lock, for debugging.
1582 struct lu_ref cll_holders;
1584 * A reference for cl_lock::cll_descr::cld_obj. For debugging.
1586 struct lu_ref_link cll_obj_ref;
1587 #ifdef CONFIG_LOCKDEP
1588 /* "dep_map" name is assumed by lockdep.h macros. */
1589 struct lockdep_map dep_map;
1594 * Per-layer part of cl_lock
1596 * \see ccc_lock, lov_lock, lovsub_lock, osc_lock
1598 struct cl_lock_slice {
1599 struct cl_lock *cls_lock;
1600 /** Object slice corresponding to this lock slice. Immutable after
1602 struct cl_object *cls_obj;
1603 const struct cl_lock_operations *cls_ops;
1604 /** Linkage into cl_lock::cll_layers. Immutable after creation. */
1605 struct list_head cls_linkage;
1609 * Possible (non-error) return values of ->clo_{enqueue,wait,unlock}().
1611 * NOTE: lov_subresult() depends on ordering here.
1613 enum cl_lock_transition {
1614 /** operation cannot be completed immediately. Wait for state change. */
1616 /** operation had to release lock mutex, restart. */
1618 /** lower layer re-enqueued. */
1624 * \see vvp_lock_ops, lov_lock_ops, lovsub_lock_ops, osc_lock_ops
1626 struct cl_lock_operations {
1628 * \name statemachine
1630 * State machine transitions. These 3 methods are called to transfer
1631 * lock from one state to another, as described in the commentary
1632 * above enum #cl_lock_state.
1634 * \retval 0 this layer has nothing more to do to before
1635 * transition to the target state happens;
1637 * \retval CLO_REPEAT method had to release and re-acquire cl_lock
1638 * mutex, repeat invocation of transition method
1639 * across all layers;
1641 * \retval CLO_WAIT this layer cannot move to the target state
1642 * immediately, as it has to wait for certain event
1643 * (e.g., the communication with the server). It
1644 * is guaranteed, that when the state transfer
1645 * becomes possible, cl_lock::cll_wq wait-queue
1646 * is signaled. Caller can wait for this event by
1647 * calling cl_lock_state_wait();
1649 * \retval -ve failure, abort state transition, move the lock
1650 * into cl_lock_state::CLS_FREEING state, and set
1651 * cl_lock::cll_error.
1653 * Once all layers voted to agree to transition (by returning 0), lock
1654 * is moved into corresponding target state. All state transition
1655 * methods are optional.
1659 * Attempts to enqueue the lock. Called top-to-bottom.
1661 * \see ccc_lock_enqueue(), lov_lock_enqueue(), lovsub_lock_enqueue(),
1662 * \see osc_lock_enqueue()
1664 int (*clo_enqueue)(const struct lu_env *env,
1665 const struct cl_lock_slice *slice,
1666 struct cl_io *io, __u32 enqflags);
1668 * Attempts to wait for enqueue result. Called top-to-bottom.
1670 * \see ccc_lock_wait(), lov_lock_wait(), osc_lock_wait()
1672 int (*clo_wait)(const struct lu_env *env,
1673 const struct cl_lock_slice *slice);
1675 * Attempts to unlock the lock. Called bottom-to-top. In addition to
1676 * usual return values of lock state-machine methods, this can return
1677 * -ESTALE to indicate that lock cannot be returned to the cache, and
1678 * has to be re-initialized.
1679 * unuse is a one-shot operation, so it must NOT return CLO_WAIT.
1681 * \see ccc_lock_unuse(), lov_lock_unuse(), osc_lock_unuse()
1683 int (*clo_unuse)(const struct lu_env *env,
1684 const struct cl_lock_slice *slice);
1686 * Notifies layer that cached lock is started being used.
1688 * \pre lock->cll_state == CLS_CACHED
1690 * \see lov_lock_use(), osc_lock_use()
1692 int (*clo_use)(const struct lu_env *env,
1693 const struct cl_lock_slice *slice);
1694 /** @} statemachine */
1696 * A method invoked when lock state is changed (as a result of state
1697 * transition). This is used, for example, to track when the state of
1698 * a sub-lock changes, to propagate this change to the corresponding
1699 * top-lock. Optional
1701 * \see lovsub_lock_state()
1703 void (*clo_state)(const struct lu_env *env,
1704 const struct cl_lock_slice *slice,
1705 enum cl_lock_state st);
1707 * Returns true, iff given lock is suitable for the given io, idea
1708 * being, that there are certain "unsafe" locks, e.g., ones acquired
1709 * for O_APPEND writes, that we don't want to re-use for a normal
1710 * write, to avoid the danger of cascading evictions. Optional. Runs
1711 * under cl_object_header::coh_lock_guard.
1713 * XXX this should take more information about lock needed by
1714 * io. Probably lock description or something similar.
1716 * \see lov_fits_into()
1718 int (*clo_fits_into)(const struct lu_env *env,
1719 const struct cl_lock_slice *slice,
1720 const struct cl_lock_descr *need,
1721 const struct cl_io *io);
1724 * Asynchronous System Traps. All of then are optional, all are
1725 * executed bottom-to-top.
1730 * Cancellation callback. Cancel a lock voluntarily, or under
1731 * the request of server.
1733 void (*clo_cancel)(const struct lu_env *env,
1734 const struct cl_lock_slice *slice);
1736 * Lock weighting ast. Executed to estimate how precious this lock
1737 * is. The sum of results across all layers is used to determine
1738 * whether lock worth keeping in cache given present memory usage.
1740 * \see osc_lock_weigh(), vvp_lock_weigh(), lovsub_lock_weigh().
1742 unsigned long (*clo_weigh)(const struct lu_env *env,
1743 const struct cl_lock_slice *slice);
1747 * \see lovsub_lock_closure()
1749 int (*clo_closure)(const struct lu_env *env,
1750 const struct cl_lock_slice *slice,
1751 struct cl_lock_closure *closure);
1753 * Executed bottom-to-top when lock description changes (e.g., as a
1754 * result of server granting more generous lock than was requested).
1756 * \see lovsub_lock_modify()
1758 int (*clo_modify)(const struct lu_env *env,
1759 const struct cl_lock_slice *slice,
1760 const struct cl_lock_descr *updated);
1762 * Notifies layers (bottom-to-top) that lock is going to be
1763 * destroyed. Responsibility of layers is to prevent new references on
1764 * this lock from being acquired once this method returns.
1766 * This can be called multiple times due to the races.
1768 * \see cl_lock_delete()
1769 * \see osc_lock_delete(), lovsub_lock_delete()
1771 void (*clo_delete)(const struct lu_env *env,
1772 const struct cl_lock_slice *slice);
1774 * Destructor. Frees resources and the slice.
1776 * \see ccc_lock_fini(), lov_lock_fini(), lovsub_lock_fini(),
1777 * \see osc_lock_fini()
1779 void (*clo_fini)(const struct lu_env *env, struct cl_lock_slice *slice);
1781 * Optional debugging helper. Prints given lock slice.
1783 int (*clo_print)(const struct lu_env *env,
1784 void *cookie, lu_printer_t p,
1785 const struct cl_lock_slice *slice);
1788 #define CL_LOCK_DEBUG(mask, env, lock, format, ...) \
1790 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1791 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1792 cl_lock_print(env, &msgdata, lu_cdebug_printer, lock); \
1793 CDEBUG(mask, format , ## __VA_ARGS__); \
1797 #define CL_LOCK_ASSERT(expr, env, lock) do { \
1801 CL_LOCK_DEBUG(D_ERROR, env, lock, "failed at %s.\n", #expr); \
1807 /** \addtogroup cl_page_list cl_page_list
1808 * Page list used to perform collective operations on a group of pages.
1810 * Pages are added to the list one by one. cl_page_list acquires a reference
1811 * for every page in it. Page list is used to perform collective operations on
1814 * - submit pages for an immediate transfer,
1816 * - own pages on behalf of certain io (waiting for each page in turn),
1820 * When list is finalized, it releases references on all pages it still has.
1822 * \todo XXX concurrency control.
1826 struct cl_page_list {
1828 struct list_head pl_pages;
1829 struct task_struct *pl_owner;
1833 * A 2-queue of pages. A convenience data-type for common use case, 2-queue
1834 * contains an incoming page list and an outgoing page list.
1837 struct cl_page_list c2_qin;
1838 struct cl_page_list c2_qout;
1841 /** @} cl_page_list */
1843 /** \addtogroup cl_io cl_io
1848 * cl_io represents a high level I/O activity like
1849 * read(2)/write(2)/truncate(2) system call, or cancellation of an extent
1852 * cl_io is a layered object, much like cl_{object,page,lock} but with one
1853 * important distinction. We want to minimize number of calls to the allocator
1854 * in the fast path, e.g., in the case of read(2) when everything is cached:
1855 * client already owns the lock over region being read, and data are cached
1856 * due to read-ahead. To avoid allocation of cl_io layers in such situations,
1857 * per-layer io state is stored in the session, associated with the io, see
1858 * struct {vvp,lov,osc}_io for example. Sessions allocation is amortized
1859 * by using free-lists, see cl_env_get().
1861 * There is a small predefined number of possible io types, enumerated in enum
1864 * cl_io is a state machine, that can be advanced concurrently by the multiple
1865 * threads. It is up to these threads to control the concurrency and,
1866 * specifically, to detect when io is done, and its state can be safely
1869 * For read/write io overall execution plan is as following:
1871 * (0) initialize io state through all layers;
1873 * (1) loop: prepare chunk of work to do
1875 * (2) call all layers to collect locks they need to process current chunk
1877 * (3) sort all locks to avoid dead-locks, and acquire them
1879 * (4) process the chunk: call per-page methods
1880 * (cl_io_operations::cio_read_page() for read,
1881 * cl_io_operations::cio_prepare_write(),
1882 * cl_io_operations::cio_commit_write() for write)
1888 * To implement the "parallel IO mode", lov layer creates sub-io's (lazily to
1889 * address allocation efficiency issues mentioned above), and returns with the
1890 * special error condition from per-page method when current sub-io has to
1891 * block. This causes io loop to be repeated, and lov switches to the next
1892 * sub-io in its cl_io_operations::cio_iter_init() implementation.
1897 /** read system call */
1899 /** write system call */
1901 /** truncate, utime system calls */
1904 * page fault handling
1908 * fsync system call handling
1909 * To write out a range of file
1913 * Miscellaneous io. This is used for occasional io activity that
1914 * doesn't fit into other types. Currently this is used for:
1916 * - cancellation of an extent lock. This io exists as a context
1917 * to write dirty pages from under the lock being canceled back
1920 * - VM induced page write-out. An io context for writing page out
1921 * for memory cleansing;
1923 * - glimpse. An io context to acquire glimpse lock.
1925 * - grouplock. An io context to acquire group lock.
1927 * CIT_MISC io is used simply as a context in which locks and pages
1928 * are manipulated. Such io has no internal "process", that is,
1929 * cl_io_loop() is never called for it.
1936 * States of cl_io state machine
1939 /** Not initialized. */
1943 /** IO iteration started. */
1947 /** Actual IO is in progress. */
1949 /** IO for the current iteration finished. */
1951 /** Locks released. */
1953 /** Iteration completed. */
1955 /** cl_io finalized. */
1960 * IO state private for a layer.
1962 * This is usually embedded into layer session data, rather than allocated
1965 * \see vvp_io, lov_io, osc_io, ccc_io
1967 struct cl_io_slice {
1968 struct cl_io *cis_io;
1969 /** corresponding object slice. Immutable after creation. */
1970 struct cl_object *cis_obj;
1971 /** io operations. Immutable after creation. */
1972 const struct cl_io_operations *cis_iop;
1974 * linkage into a list of all slices for a given cl_io, hanging off
1975 * cl_io::ci_layers. Immutable after creation.
1977 struct list_head cis_linkage;
1980 typedef void (*cl_commit_cbt)(const struct lu_env *, struct cl_io *,
1984 * Per-layer io operations.
1985 * \see vvp_io_ops, lov_io_ops, lovsub_io_ops, osc_io_ops
1987 struct cl_io_operations {
1989 * Vector of io state transition methods for every io type.
1991 * \see cl_page_operations::io
1995 * Prepare io iteration at a given layer.
1997 * Called top-to-bottom at the beginning of each iteration of
1998 * "io loop" (if it makes sense for this type of io). Here
1999 * layer selects what work it will do during this iteration.
2001 * \see cl_io_operations::cio_iter_fini()
2003 int (*cio_iter_init) (const struct lu_env *env,
2004 const struct cl_io_slice *slice);
2006 * Finalize io iteration.
2008 * Called bottom-to-top at the end of each iteration of "io
2009 * loop". Here layers can decide whether IO has to be
2012 * \see cl_io_operations::cio_iter_init()
2014 void (*cio_iter_fini) (const struct lu_env *env,
2015 const struct cl_io_slice *slice);
2017 * Collect locks for the current iteration of io.
2019 * Called top-to-bottom to collect all locks necessary for
2020 * this iteration. This methods shouldn't actually enqueue
2021 * anything, instead it should post a lock through
2022 * cl_io_lock_add(). Once all locks are collected, they are
2023 * sorted and enqueued in the proper order.
2025 int (*cio_lock) (const struct lu_env *env,
2026 const struct cl_io_slice *slice);
2028 * Finalize unlocking.
2030 * Called bottom-to-top to finish layer specific unlocking
2031 * functionality, after generic code released all locks
2032 * acquired by cl_io_operations::cio_lock().
2034 void (*cio_unlock)(const struct lu_env *env,
2035 const struct cl_io_slice *slice);
2037 * Start io iteration.
2039 * Once all locks are acquired, called top-to-bottom to
2040 * commence actual IO. In the current implementation,
2041 * top-level vvp_io_{read,write}_start() does all the work
2042 * synchronously by calling generic_file_*(), so other layers
2043 * are called when everything is done.
2045 int (*cio_start)(const struct lu_env *env,
2046 const struct cl_io_slice *slice);
2048 * Called top-to-bottom at the end of io loop. Here layer
2049 * might wait for an unfinished asynchronous io.
2051 void (*cio_end) (const struct lu_env *env,
2052 const struct cl_io_slice *slice);
2054 * Called bottom-to-top to notify layers that read/write IO
2055 * iteration finished, with \a nob bytes transferred.
2057 void (*cio_advance)(const struct lu_env *env,
2058 const struct cl_io_slice *slice,
2061 * Called once per io, bottom-to-top to release io resources.
2063 void (*cio_fini) (const struct lu_env *env,
2064 const struct cl_io_slice *slice);
2068 * Submit pages from \a queue->c2_qin for IO, and move
2069 * successfully submitted pages into \a queue->c2_qout. Return
2070 * non-zero if failed to submit even the single page. If
2071 * submission failed after some pages were moved into \a
2072 * queue->c2_qout, completion callback with non-zero ioret is
2075 int (*cio_submit)(const struct lu_env *env,
2076 const struct cl_io_slice *slice,
2077 enum cl_req_type crt,
2078 struct cl_2queue *queue);
2080 * Queue async page for write.
2081 * The difference between cio_submit and cio_queue is that
2082 * cio_submit is for urgent request.
2084 int (*cio_commit_async)(const struct lu_env *env,
2085 const struct cl_io_slice *slice,
2086 struct cl_page_list *queue, int from, int to,
2089 * Read missing page.
2091 * Called by a top-level cl_io_operations::op[CIT_READ]::cio_start()
2092 * method, when it hits not-up-to-date page in the range. Optional.
2094 * \pre io->ci_type == CIT_READ
2096 int (*cio_read_page)(const struct lu_env *env,
2097 const struct cl_io_slice *slice,
2098 const struct cl_page_slice *page);
2100 * Optional debugging helper. Print given io slice.
2102 int (*cio_print)(const struct lu_env *env, void *cookie,
2103 lu_printer_t p, const struct cl_io_slice *slice);
2107 * Flags to lock enqueue procedure.
2112 * instruct server to not block, if conflicting lock is found. Instead
2113 * -EWOULDBLOCK is returned immediately.
2115 CEF_NONBLOCK = 0x00000001,
2117 * take lock asynchronously (out of order), as it cannot
2118 * deadlock. This is for LDLM_FL_HAS_INTENT locks used for glimpsing.
2120 CEF_ASYNC = 0x00000002,
2122 * tell the server to instruct (though a flag in the blocking ast) an
2123 * owner of the conflicting lock, that it can drop dirty pages
2124 * protected by this lock, without sending them to the server.
2126 CEF_DISCARD_DATA = 0x00000004,
2128 * tell the sub layers that it must be a `real' lock. This is used for
2129 * mmapped-buffer locks and glimpse locks that must be never converted
2130 * into lockless mode.
2132 * \see vvp_mmap_locks(), cl_glimpse_lock().
2134 CEF_MUST = 0x00000008,
2136 * tell the sub layers that never request a `real' lock. This flag is
2137 * not used currently.
2139 * cl_io::ci_lockreq and CEF_{MUST,NEVER} flags specify lockless
2140 * conversion policy: ci_lockreq describes generic information of lock
2141 * requirement for this IO, especially for locks which belong to the
2142 * object doing IO; however, lock itself may have precise requirements
2143 * that are described by the enqueue flags.
2145 CEF_NEVER = 0x00000010,
2147 * for async glimpse lock.
2149 CEF_AGL = 0x00000020,
2151 * mask of enq_flags.
2153 CEF_MASK = 0x0000003f,
2157 * Link between lock and io. Intermediate structure is needed, because the
2158 * same lock can be part of multiple io's simultaneously.
2160 struct cl_io_lock_link {
2161 /** linkage into one of cl_lockset lists. */
2162 struct list_head cill_linkage;
2163 struct cl_lock_descr cill_descr;
2164 struct cl_lock *cill_lock;
2165 /** optional destructor */
2166 void (*cill_fini)(const struct lu_env *env,
2167 struct cl_io_lock_link *link);
2171 * Lock-set represents a collection of locks, that io needs at a
2172 * time. Generally speaking, client tries to avoid holding multiple locks when
2175 * - holding extent locks over multiple ost's introduces the danger of
2176 * "cascading timeouts";
2178 * - holding multiple locks over the same ost is still dead-lock prone,
2179 * see comment in osc_lock_enqueue(),
2181 * but there are certain situations where this is unavoidable:
2183 * - O_APPEND writes have to take [0, EOF] lock for correctness;
2185 * - truncate has to take [new-size, EOF] lock for correctness;
2187 * - SNS has to take locks across full stripe for correctness;
2189 * - in the case when user level buffer, supplied to {read,write}(file0),
2190 * is a part of a memory mapped lustre file, client has to take a dlm
2191 * locks on file0, and all files that back up the buffer (or a part of
2192 * the buffer, that is being processed in the current chunk, in any
2193 * case, there are situations where at least 2 locks are necessary).
2195 * In such cases we at least try to take locks in the same consistent
2196 * order. To this end, all locks are first collected, then sorted, and then
2200 /** locks to be acquired. */
2201 struct list_head cls_todo;
2202 /** locks currently being processed. */
2203 struct list_head cls_curr;
2204 /** locks acquired. */
2205 struct list_head cls_done;
2209 * Lock requirements(demand) for IO. It should be cl_io_lock_req,
2210 * but 'req' is always to be thought as 'request' :-)
2212 enum cl_io_lock_dmd {
2213 /** Always lock data (e.g., O_APPEND). */
2215 /** Layers are free to decide between local and global locking. */
2217 /** Never lock: there is no cache (e.g., liblustre). */
2221 enum cl_fsync_mode {
2222 /** start writeback, do not wait for them to finish */
2224 /** start writeback and wait for them to finish */
2226 /** discard all of dirty pages in a specific file range */
2227 CL_FSYNC_DISCARD = 2,
2228 /** start writeback and make sure they have reached storage before
2229 * return. OST_SYNC RPC must be issued and finished */
2233 struct cl_io_rw_common {
2243 * cl_io is shared by all threads participating in this IO (in current
2244 * implementation only one thread advances IO, but parallel IO design and
2245 * concurrent copy_*_user() require multiple threads acting on the same IO. It
2246 * is up to these threads to serialize their activities, including updates to
2247 * mutable cl_io fields.
2250 /** type of this IO. Immutable after creation. */
2251 enum cl_io_type ci_type;
2252 /** current state of cl_io state machine. */
2253 enum cl_io_state ci_state;
2254 /** main object this io is against. Immutable after creation. */
2255 struct cl_object *ci_obj;
2257 * Upper layer io, of which this io is a part of. Immutable after
2260 struct cl_io *ci_parent;
2261 /** List of slices. Immutable after creation. */
2262 struct list_head ci_layers;
2263 /** list of locks (to be) acquired by this io. */
2264 struct cl_lockset ci_lockset;
2265 /** lock requirements, this is just a help info for sublayers. */
2266 enum cl_io_lock_dmd ci_lockreq;
2269 struct cl_io_rw_common rd;
2272 struct cl_io_rw_common wr;
2276 struct cl_io_rw_common ci_rw;
2277 struct cl_setattr_io {
2278 struct ost_lvb sa_attr;
2279 unsigned int sa_valid;
2280 struct obd_capa *sa_capa;
2282 struct cl_fault_io {
2283 /** page index within file. */
2285 /** bytes valid byte on a faulted page. */
2287 /** writable page? for nopage() only */
2289 /** page of an executable? */
2291 /** page_mkwrite() */
2293 /** resulting page */
2294 struct cl_page *ft_page;
2296 struct cl_fsync_io {
2299 struct obd_capa *fi_capa;
2300 /** file system level fid */
2301 struct lu_fid *fi_fid;
2302 enum cl_fsync_mode fi_mode;
2303 /* how many pages were written/discarded */
2304 unsigned int fi_nr_written;
2307 struct cl_2queue ci_queue;
2310 unsigned int ci_continue:1,
2312 * This io has held grouplock, to inform sublayers that
2313 * don't do lockless i/o.
2317 * The whole IO need to be restarted because layout has been changed
2321 * to not refresh layout - the IO issuer knows that the layout won't
2322 * change(page operations, layout change causes all page to be
2323 * discarded), or it doesn't matter if it changes(sync).
2327 * Check if layout changed after the IO finishes. Mainly for HSM
2328 * requirement. If IO occurs to openning files, it doesn't need to
2329 * verify layout because HSM won't release openning files.
2330 * Right now, only two opertaions need to verify layout: glimpse
2335 * file is released, restore has to to be triggered by vvp layer
2337 ci_restore_needed:1,
2343 * Number of pages owned by this IO. For invariant checking.
2345 unsigned ci_owned_nr;
2350 /** \addtogroup cl_req cl_req
2355 * There are two possible modes of transfer initiation on the client:
2357 * - immediate transfer: this is started when a high level io wants a page
2358 * or a collection of pages to be transferred right away. Examples:
2359 * read-ahead, synchronous read in the case of non-page aligned write,
2360 * page write-out as a part of extent lock cancellation, page write-out
2361 * as a part of memory cleansing. Immediate transfer can be both
2362 * cl_req_type::CRT_READ and cl_req_type::CRT_WRITE;
2364 * - opportunistic transfer (cl_req_type::CRT_WRITE only), that happens
2365 * when io wants to transfer a page to the server some time later, when
2366 * it can be done efficiently. Example: pages dirtied by the write(2)
2369 * In any case, transfer takes place in the form of a cl_req, which is a
2370 * representation for a network RPC.
2372 * Pages queued for an opportunistic transfer are cached until it is decided
2373 * that efficient RPC can be composed of them. This decision is made by "a
2374 * req-formation engine", currently implemented as a part of osc
2375 * layer. Req-formation depends on many factors: the size of the resulting
2376 * RPC, whether or not multi-object RPCs are supported by the server,
2377 * max-rpc-in-flight limitations, size of the dirty cache, etc.
2379 * For the immediate transfer io submits a cl_page_list, that req-formation
2380 * engine slices into cl_req's, possibly adding cached pages to some of
2381 * the resulting req's.
2383 * Whenever a page from cl_page_list is added to a newly constructed req, its
2384 * cl_page_operations::cpo_prep() layer methods are called. At that moment,
2385 * page state is atomically changed from cl_page_state::CPS_OWNED to
2386 * cl_page_state::CPS_PAGEOUT or cl_page_state::CPS_PAGEIN, cl_page::cp_owner
2387 * is zeroed, and cl_page::cp_req is set to the
2388 * req. cl_page_operations::cpo_prep() method at the particular layer might
2389 * return -EALREADY to indicate that it does not need to submit this page
2390 * at all. This is possible, for example, if page, submitted for read,
2391 * became up-to-date in the meantime; and for write, the page don't have
2392 * dirty bit marked. \see cl_io_submit_rw()
2394 * Whenever a cached page is added to a newly constructed req, its
2395 * cl_page_operations::cpo_make_ready() layer methods are called. At that
2396 * moment, page state is atomically changed from cl_page_state::CPS_CACHED to
2397 * cl_page_state::CPS_PAGEOUT, and cl_page::cp_req is set to
2398 * req. cl_page_operations::cpo_make_ready() method at the particular layer
2399 * might return -EAGAIN to indicate that this page is not eligible for the
2400 * transfer right now.
2404 * Plan is to divide transfers into "priority bands" (indicated when
2405 * submitting cl_page_list, and queuing a page for the opportunistic transfer)
2406 * and allow glueing of cached pages to immediate transfers only within single
2407 * band. This would make high priority transfers (like lock cancellation or
2408 * memory pressure induced write-out) really high priority.
2413 * Per-transfer attributes.
2415 struct cl_req_attr {
2416 /** Generic attributes for the server consumption. */
2417 struct obdo *cra_oa;
2419 struct obd_capa *cra_capa;
2421 char cra_jobid[JOBSTATS_JOBID_SIZE];
2425 * Transfer request operations definable at every layer.
2427 * Concurrency: transfer formation engine synchronizes calls to all transfer
2430 struct cl_req_operations {
2432 * Invoked top-to-bottom by cl_req_prep() when transfer formation is
2433 * complete (all pages are added).
2435 * \see osc_req_prep()
2437 int (*cro_prep)(const struct lu_env *env,
2438 const struct cl_req_slice *slice);
2440 * Called top-to-bottom to fill in \a oa fields. This is called twice
2441 * with different flags, see bug 10150 and osc_build_req().
2443 * \param obj an object from cl_req which attributes are to be set in
2446 * \param oa struct obdo where attributes are placed
2448 * \param flags \a oa fields to be filled.
2450 void (*cro_attr_set)(const struct lu_env *env,
2451 const struct cl_req_slice *slice,
2452 const struct cl_object *obj,
2453 struct cl_req_attr *attr, obd_valid flags);
2455 * Called top-to-bottom from cl_req_completion() to notify layers that
2456 * transfer completed. Has to free all state allocated by
2457 * cl_device_operations::cdo_req_init().
2459 void (*cro_completion)(const struct lu_env *env,
2460 const struct cl_req_slice *slice, int ioret);
2464 * A per-object state that (potentially multi-object) transfer request keeps.
2467 /** object itself */
2468 struct cl_object *ro_obj;
2469 /** reference to cl_req_obj::ro_obj. For debugging. */
2470 struct lu_ref_link ro_obj_ref;
2471 /* something else? Number of pages for a given object? */
2477 * Transfer requests are not reference counted, because IO sub-system owns
2478 * them exclusively and knows when to free them.
2482 * cl_req is created by cl_req_alloc() that calls
2483 * cl_device_operations::cdo_req_init() device methods to allocate per-req
2484 * state in every layer.
2486 * Then pages are added (cl_req_page_add()), req keeps track of all objects it
2487 * contains pages for.
2489 * Once all pages were collected, cl_page_operations::cpo_prep() method is
2490 * called top-to-bottom. At that point layers can modify req, let it pass, or
2491 * deny it completely. This is to support things like SNS that have transfer
2492 * ordering requirements invisible to the individual req-formation engine.
2494 * On transfer completion (or transfer timeout, or failure to initiate the
2495 * transfer of an allocated req), cl_req_operations::cro_completion() method
2496 * is called, after execution of cl_page_operations::cpo_completion() of all
2500 enum cl_req_type crq_type;
2501 /** A list of pages being transfered */
2502 struct list_head crq_pages;
2503 /** Number of pages in cl_req::crq_pages */
2504 unsigned crq_nrpages;
2505 /** An array of objects which pages are in ->crq_pages */
2506 struct cl_req_obj *crq_o;
2507 /** Number of elements in cl_req::crq_objs[] */
2508 unsigned crq_nrobjs;
2509 struct list_head crq_layers;
2513 * Per-layer state for request.
2515 struct cl_req_slice {
2516 struct cl_req *crs_req;
2517 struct cl_device *crs_dev;
2518 struct list_head crs_linkage;
2519 const struct cl_req_operations *crs_ops;
2524 enum cache_stats_item {
2525 /** how many cache lookups were performed */
2527 /** how many times cache lookup resulted in a hit */
2529 /** how many entities are in the cache right now */
2531 /** how many entities in the cache are actively used (and cannot be
2532 * evicted) right now */
2534 /** how many entities were created at all */
2539 #define CS_NAMES { "lookup", "hit", "total", "busy", "create" }
2542 * Stats for a generic cache (similar to inode, lu_object, etc. caches).
2544 struct cache_stats {
2545 const char *cs_name;
2546 atomic_t cs_stats[CS_NR];
2549 /** These are not exported so far */
2550 void cache_stats_init (struct cache_stats *cs, const char *name);
2553 * Client-side site. This represents particular client stack. "Global"
2554 * variables should (directly or indirectly) be added here to allow multiple
2555 * clients to co-exist in the single address space.
2558 struct lu_site cs_lu;
2560 * Statistical counters. Atomics do not scale, something better like
2561 * per-cpu counters is needed.
2563 * These are exported as /proc/fs/lustre/llite/.../site
2565 * When interpreting keep in mind that both sub-locks (and sub-pages)
2566 * and top-locks (and top-pages) are accounted here.
2568 struct cache_stats cs_pages;
2569 struct cache_stats cs_locks;
2570 atomic_t cs_pages_state[CPS_NR];
2571 atomic_t cs_locks_state[CLS_NR];
2574 int cl_site_init(struct cl_site *s, struct cl_device *top);
2575 void cl_site_fini(struct cl_site *s);
2576 void cl_stack_fini(const struct lu_env *env, struct cl_device *cl);
2579 * Output client site statistical counters into a buffer. Suitable for
2580 * ll_rd_*()-style functions.
2582 int cl_site_stats_print(const struct cl_site *site, struct seq_file *m);
2587 * Type conversion and accessory functions.
2591 static inline struct cl_site *lu2cl_site(const struct lu_site *site)
2593 return container_of(site, struct cl_site, cs_lu);
2596 static inline int lu_device_is_cl(const struct lu_device *d)
2598 return d->ld_type->ldt_tags & LU_DEVICE_CL;
2601 static inline struct cl_device *lu2cl_dev(const struct lu_device *d)
2603 LASSERT(d == NULL || IS_ERR(d) || lu_device_is_cl(d));
2604 return container_of0(d, struct cl_device, cd_lu_dev);
2607 static inline struct lu_device *cl2lu_dev(struct cl_device *d)
2609 return &d->cd_lu_dev;
2612 static inline struct cl_object *lu2cl(const struct lu_object *o)
2614 LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->lo_dev));
2615 return container_of0(o, struct cl_object, co_lu);
2618 static inline const struct cl_object_conf *
2619 lu2cl_conf(const struct lu_object_conf *conf)
2621 return container_of0(conf, struct cl_object_conf, coc_lu);
2624 static inline struct cl_object *cl_object_next(const struct cl_object *obj)
2626 return obj ? lu2cl(lu_object_next(&obj->co_lu)) : NULL;
2629 static inline struct cl_object_header *luh2coh(const struct lu_object_header *h)
2631 return container_of0(h, struct cl_object_header, coh_lu);
2634 static inline struct cl_site *cl_object_site(const struct cl_object *obj)
2636 return lu2cl_site(obj->co_lu.lo_dev->ld_site);
2640 struct cl_object_header *cl_object_header(const struct cl_object *obj)
2642 return luh2coh(obj->co_lu.lo_header);
2645 static inline int cl_device_init(struct cl_device *d, struct lu_device_type *t)
2647 return lu_device_init(&d->cd_lu_dev, t);
2650 static inline void cl_device_fini(struct cl_device *d)
2652 lu_device_fini(&d->cd_lu_dev);
2655 void cl_page_slice_add(struct cl_page *page, struct cl_page_slice *slice,
2656 struct cl_object *obj, pgoff_t index,
2657 const struct cl_page_operations *ops);
2658 void cl_lock_slice_add(struct cl_lock *lock, struct cl_lock_slice *slice,
2659 struct cl_object *obj,
2660 const struct cl_lock_operations *ops);
2661 void cl_io_slice_add(struct cl_io *io, struct cl_io_slice *slice,
2662 struct cl_object *obj, const struct cl_io_operations *ops);
2663 void cl_req_slice_add(struct cl_req *req, struct cl_req_slice *slice,
2664 struct cl_device *dev,
2665 const struct cl_req_operations *ops);
2668 /** \defgroup cl_object cl_object
2670 struct cl_object *cl_object_top (struct cl_object *o);
2671 struct cl_object *cl_object_find(const struct lu_env *env, struct cl_device *cd,
2672 const struct lu_fid *fid,
2673 const struct cl_object_conf *c);
2675 int cl_object_header_init(struct cl_object_header *h);
2676 void cl_object_header_fini(struct cl_object_header *h);
2677 void cl_object_put (const struct lu_env *env, struct cl_object *o);
2678 void cl_object_get (struct cl_object *o);
2679 void cl_object_attr_lock (struct cl_object *o);
2680 void cl_object_attr_unlock(struct cl_object *o);
2681 int cl_object_attr_get (const struct lu_env *env, struct cl_object *obj,
2682 struct cl_attr *attr);
2683 int cl_object_attr_set (const struct lu_env *env, struct cl_object *obj,
2684 const struct cl_attr *attr, unsigned valid);
2685 int cl_object_glimpse (const struct lu_env *env, struct cl_object *obj,
2686 struct ost_lvb *lvb);
2687 int cl_conf_set (const struct lu_env *env, struct cl_object *obj,
2688 const struct cl_object_conf *conf);
2689 void cl_object_prune (const struct lu_env *env, struct cl_object *obj);
2690 void cl_object_kill (const struct lu_env *env, struct cl_object *obj);
2691 int cl_object_has_locks (struct cl_object *obj);
2694 * Returns true, iff \a o0 and \a o1 are slices of the same object.
2696 static inline int cl_object_same(struct cl_object *o0, struct cl_object *o1)
2698 return cl_object_header(o0) == cl_object_header(o1);
2701 static inline void cl_object_page_init(struct cl_object *clob, int size)
2703 clob->co_slice_off = cl_object_header(clob)->coh_page_bufsize;
2704 cl_object_header(clob)->coh_page_bufsize += cfs_size_round(size);
2705 WARN_ON(cl_object_header(clob)->coh_page_bufsize > 512);
2708 static inline void *cl_object_page_slice(struct cl_object *clob,
2709 struct cl_page *page)
2711 return (void *)((char *)page + clob->co_slice_off);
2715 * Return refcount of cl_object.
2717 static inline int cl_object_refc(struct cl_object *clob)
2719 struct lu_object_header *header = clob->co_lu.lo_header;
2720 return atomic_read(&header->loh_ref);
2725 /** \defgroup cl_page cl_page
2733 /* callback of cl_page_gang_lookup() */
2735 struct cl_page *cl_page_find (const struct lu_env *env,
2736 struct cl_object *obj,
2737 pgoff_t idx, struct page *vmpage,
2738 enum cl_page_type type);
2739 struct cl_page *cl_page_alloc (const struct lu_env *env,
2740 struct cl_object *o, pgoff_t ind,
2741 struct page *vmpage,
2742 enum cl_page_type type);
2743 void cl_page_get (struct cl_page *page);
2744 void cl_page_put (const struct lu_env *env,
2745 struct cl_page *page);
2746 void cl_page_print (const struct lu_env *env, void *cookie,
2747 lu_printer_t printer,
2748 const struct cl_page *pg);
2749 void cl_page_header_print(const struct lu_env *env, void *cookie,
2750 lu_printer_t printer,
2751 const struct cl_page *pg);
2752 struct cl_page *cl_vmpage_page (struct page *vmpage, struct cl_object *obj);
2753 struct cl_page *cl_page_top (struct cl_page *page);
2755 const struct cl_page_slice *cl_page_at(const struct cl_page *page,
2756 const struct lu_device_type *dtype);
2761 * Functions dealing with the ownership of page by io.
2765 int cl_page_own (const struct lu_env *env,
2766 struct cl_io *io, struct cl_page *page);
2767 int cl_page_own_try (const struct lu_env *env,
2768 struct cl_io *io, struct cl_page *page);
2769 void cl_page_assume (const struct lu_env *env,
2770 struct cl_io *io, struct cl_page *page);
2771 void cl_page_unassume (const struct lu_env *env,
2772 struct cl_io *io, struct cl_page *pg);
2773 void cl_page_disown (const struct lu_env *env,
2774 struct cl_io *io, struct cl_page *page);
2775 int cl_page_is_owned (const struct cl_page *pg, const struct cl_io *io);
2782 * Functions dealing with the preparation of a page for a transfer, and
2783 * tracking transfer state.
2786 int cl_page_prep (const struct lu_env *env, struct cl_io *io,
2787 struct cl_page *pg, enum cl_req_type crt);
2788 void cl_page_completion (const struct lu_env *env,
2789 struct cl_page *pg, enum cl_req_type crt, int ioret);
2790 int cl_page_make_ready (const struct lu_env *env, struct cl_page *pg,
2791 enum cl_req_type crt);
2792 int cl_page_cache_add (const struct lu_env *env, struct cl_io *io,
2793 struct cl_page *pg, enum cl_req_type crt);
2794 void cl_page_clip (const struct lu_env *env, struct cl_page *pg,
2796 int cl_page_cancel (const struct lu_env *env, struct cl_page *page);
2797 int cl_page_flush (const struct lu_env *env, struct cl_io *io,
2798 struct cl_page *pg);
2804 * \name helper routines
2805 * Functions to discard, delete and export a cl_page.
2808 void cl_page_discard (const struct lu_env *env, struct cl_io *io,
2809 struct cl_page *pg);
2810 void cl_page_delete (const struct lu_env *env, struct cl_page *pg);
2811 int cl_page_is_vmlocked (const struct lu_env *env,
2812 const struct cl_page *pg);
2813 void cl_page_export (const struct lu_env *env,
2814 struct cl_page *pg, int uptodate);
2815 int cl_page_is_under_lock(const struct lu_env *env, struct cl_io *io,
2816 struct cl_page *page, pgoff_t *max_index);
2817 loff_t cl_offset (const struct cl_object *obj, pgoff_t idx);
2818 pgoff_t cl_index (const struct cl_object *obj, loff_t offset);
2819 int cl_page_size (const struct cl_object *obj);
2820 int cl_pages_prune (const struct lu_env *env, struct cl_object *obj);
2822 void cl_lock_print (const struct lu_env *env, void *cookie,
2823 lu_printer_t printer, const struct cl_lock *lock);
2824 void cl_lock_descr_print(const struct lu_env *env, void *cookie,
2825 lu_printer_t printer,
2826 const struct cl_lock_descr *descr);
2831 /** \defgroup cl_lock cl_lock
2834 struct cl_lock *cl_lock_hold(const struct lu_env *env, const struct cl_io *io,
2835 const struct cl_lock_descr *need,
2836 const char *scope, const void *source);
2837 struct cl_lock *cl_lock_peek(const struct lu_env *env, const struct cl_io *io,
2838 const struct cl_lock_descr *need,
2839 const char *scope, const void *source);
2840 struct cl_lock *cl_lock_request(const struct lu_env *env, struct cl_io *io,
2841 const struct cl_lock_descr *need,
2842 const char *scope, const void *source);
2843 struct cl_lock *cl_lock_at_pgoff(const struct lu_env *env,
2844 struct cl_object *obj, pgoff_t index,
2845 struct cl_lock *except, int pending,
2847 const struct cl_lock_slice *cl_lock_at(const struct cl_lock *lock,
2848 const struct lu_device_type *dtype);
2850 void cl_lock_get (struct cl_lock *lock);
2851 void cl_lock_get_trust (struct cl_lock *lock);
2852 void cl_lock_put (const struct lu_env *env, struct cl_lock *lock);
2853 void cl_lock_hold_add (const struct lu_env *env, struct cl_lock *lock,
2854 const char *scope, const void *source);
2855 void cl_lock_hold_release(const struct lu_env *env, struct cl_lock *lock,
2856 const char *scope, const void *source);
2857 void cl_lock_unhold (const struct lu_env *env, struct cl_lock *lock,
2858 const char *scope, const void *source);
2859 void cl_lock_release (const struct lu_env *env, struct cl_lock *lock,
2860 const char *scope, const void *source);
2861 void cl_lock_user_add (const struct lu_env *env, struct cl_lock *lock);
2862 void cl_lock_user_del (const struct lu_env *env, struct cl_lock *lock);
2864 enum cl_lock_state cl_lock_intransit(const struct lu_env *env,
2865 struct cl_lock *lock);
2866 void cl_lock_extransit(const struct lu_env *env, struct cl_lock *lock,
2867 enum cl_lock_state state);
2868 int cl_lock_is_intransit(struct cl_lock *lock);
2870 int cl_lock_enqueue_wait(const struct lu_env *env, struct cl_lock *lock,
2873 /** \name statemachine statemachine
2874 * Interface to lock state machine consists of 3 parts:
2876 * - "try" functions that attempt to effect a state transition. If state
2877 * transition is not possible right now (e.g., if it has to wait for some
2878 * asynchronous event to occur), these functions return
2879 * cl_lock_transition::CLO_WAIT.
2881 * - "non-try" functions that implement synchronous blocking interface on
2882 * top of non-blocking "try" functions. These functions repeatedly call
2883 * corresponding "try" versions, and if state transition is not possible
2884 * immediately, wait for lock state change.
2886 * - methods from cl_lock_operations, called by "try" functions. Lock can
2887 * be advanced to the target state only when all layers voted that they
2888 * are ready for this transition. "Try" functions call methods under lock
2889 * mutex. If a layer had to release a mutex, it re-acquires it and returns
2890 * cl_lock_transition::CLO_REPEAT, causing "try" function to call all
2893 * TRY NON-TRY METHOD FINAL STATE
2895 * cl_enqueue_try() cl_enqueue() cl_lock_operations::clo_enqueue() CLS_ENQUEUED
2897 * cl_wait_try() cl_wait() cl_lock_operations::clo_wait() CLS_HELD
2899 * cl_unuse_try() cl_unuse() cl_lock_operations::clo_unuse() CLS_CACHED
2901 * cl_use_try() NONE cl_lock_operations::clo_use() CLS_HELD
2905 int cl_enqueue (const struct lu_env *env, struct cl_lock *lock,
2906 struct cl_io *io, __u32 flags);
2907 int cl_wait (const struct lu_env *env, struct cl_lock *lock);
2908 void cl_unuse (const struct lu_env *env, struct cl_lock *lock);
2909 int cl_enqueue_try(const struct lu_env *env, struct cl_lock *lock,
2910 struct cl_io *io, __u32 flags);
2911 int cl_unuse_try (const struct lu_env *env, struct cl_lock *lock);
2912 int cl_wait_try (const struct lu_env *env, struct cl_lock *lock);
2913 int cl_use_try (const struct lu_env *env, struct cl_lock *lock, int atomic);
2915 /** @} statemachine */
2917 void cl_lock_signal (const struct lu_env *env, struct cl_lock *lock);
2918 int cl_lock_state_wait (const struct lu_env *env, struct cl_lock *lock);
2919 void cl_lock_state_set (const struct lu_env *env, struct cl_lock *lock,
2920 enum cl_lock_state state);
2921 int cl_queue_match(const struct list_head *queue,
2922 const struct cl_lock_descr *need);
2924 void cl_lock_mutex_get (const struct lu_env *env, struct cl_lock *lock);
2925 int cl_lock_mutex_try (const struct lu_env *env, struct cl_lock *lock);
2926 void cl_lock_mutex_put (const struct lu_env *env, struct cl_lock *lock);
2927 int cl_lock_is_mutexed (struct cl_lock *lock);
2928 int cl_lock_nr_mutexed (const struct lu_env *env);
2929 int cl_lock_discard_pages(const struct lu_env *env, struct cl_lock *lock);
2930 int cl_lock_ext_match (const struct cl_lock_descr *has,
2931 const struct cl_lock_descr *need);
2932 int cl_lock_descr_match(const struct cl_lock_descr *has,
2933 const struct cl_lock_descr *need);
2934 int cl_lock_mode_match (enum cl_lock_mode has, enum cl_lock_mode need);
2935 int cl_lock_modify (const struct lu_env *env, struct cl_lock *lock,
2936 const struct cl_lock_descr *desc);
2938 void cl_lock_closure_init (const struct lu_env *env,
2939 struct cl_lock_closure *closure,
2940 struct cl_lock *origin, int wait);
2941 void cl_lock_closure_fini (struct cl_lock_closure *closure);
2942 int cl_lock_closure_build(const struct lu_env *env, struct cl_lock *lock,
2943 struct cl_lock_closure *closure);
2944 void cl_lock_disclosure (const struct lu_env *env,
2945 struct cl_lock_closure *closure);
2946 int cl_lock_enclosure (const struct lu_env *env, struct cl_lock *lock,
2947 struct cl_lock_closure *closure);
2949 void cl_lock_cancel(const struct lu_env *env, struct cl_lock *lock);
2950 void cl_lock_delete(const struct lu_env *env, struct cl_lock *lock);
2951 void cl_lock_error (const struct lu_env *env, struct cl_lock *lock, int error);
2952 void cl_locks_prune(const struct lu_env *env, struct cl_object *obj, int wait);
2954 unsigned long cl_lock_weigh(const struct lu_env *env, struct cl_lock *lock);
2958 /** \defgroup cl_io cl_io
2961 int cl_io_init (const struct lu_env *env, struct cl_io *io,
2962 enum cl_io_type iot, struct cl_object *obj);
2963 int cl_io_sub_init (const struct lu_env *env, struct cl_io *io,
2964 enum cl_io_type iot, struct cl_object *obj);
2965 int cl_io_rw_init (const struct lu_env *env, struct cl_io *io,
2966 enum cl_io_type iot, loff_t pos, size_t count);
2967 int cl_io_loop (const struct lu_env *env, struct cl_io *io);
2969 void cl_io_fini (const struct lu_env *env, struct cl_io *io);
2970 int cl_io_iter_init (const struct lu_env *env, struct cl_io *io);
2971 void cl_io_iter_fini (const struct lu_env *env, struct cl_io *io);
2972 int cl_io_lock (const struct lu_env *env, struct cl_io *io);
2973 void cl_io_unlock (const struct lu_env *env, struct cl_io *io);
2974 int cl_io_start (const struct lu_env *env, struct cl_io *io);
2975 void cl_io_end (const struct lu_env *env, struct cl_io *io);
2976 int cl_io_lock_add (const struct lu_env *env, struct cl_io *io,
2977 struct cl_io_lock_link *link);
2978 int cl_io_lock_alloc_add(const struct lu_env *env, struct cl_io *io,
2979 struct cl_lock_descr *descr);
2980 int cl_io_read_page (const struct lu_env *env, struct cl_io *io,
2981 struct cl_page *page);
2982 int cl_io_submit_rw (const struct lu_env *env, struct cl_io *io,
2983 enum cl_req_type iot, struct cl_2queue *queue);
2984 int cl_io_submit_sync (const struct lu_env *env, struct cl_io *io,
2985 enum cl_req_type iot, struct cl_2queue *queue,
2987 int cl_io_commit_async (const struct lu_env *env, struct cl_io *io,
2988 struct cl_page_list *queue, int from, int to,
2990 void cl_io_rw_advance (const struct lu_env *env, struct cl_io *io,
2992 int cl_io_cancel (const struct lu_env *env, struct cl_io *io,
2993 struct cl_page_list *queue);
2994 int cl_io_is_going (const struct lu_env *env);
2997 * True, iff \a io is an O_APPEND write(2).
2999 static inline int cl_io_is_append(const struct cl_io *io)
3001 return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_append;
3004 static inline int cl_io_is_sync_write(const struct cl_io *io)
3006 return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_sync;
3009 static inline int cl_io_is_mkwrite(const struct cl_io *io)
3011 return io->ci_type == CIT_FAULT && io->u.ci_fault.ft_mkwrite;
3015 * True, iff \a io is a truncate(2).
3017 static inline int cl_io_is_trunc(const struct cl_io *io)
3019 return io->ci_type == CIT_SETATTR &&
3020 (io->u.ci_setattr.sa_valid & ATTR_SIZE);
3023 struct cl_io *cl_io_top(struct cl_io *io);
3025 void cl_io_print(const struct lu_env *env, void *cookie,
3026 lu_printer_t printer, const struct cl_io *io);
3028 #define CL_IO_SLICE_CLEAN(foo_io, base) \
3030 typeof(foo_io) __foo_io = (foo_io); \
3032 CLASSERT(offsetof(typeof(*__foo_io), base) == 0); \
3033 memset(&__foo_io->base + 1, 0, \
3034 (sizeof *__foo_io) - sizeof __foo_io->base); \
3039 /** \defgroup cl_page_list cl_page_list
3043 * Last page in the page list.
3045 static inline struct cl_page *cl_page_list_last(struct cl_page_list *plist)
3047 LASSERT(plist->pl_nr > 0);
3048 return list_entry(plist->pl_pages.prev, struct cl_page, cp_batch);
3051 static inline struct cl_page *cl_page_list_first(struct cl_page_list *plist)
3053 LASSERT(plist->pl_nr > 0);
3054 return list_entry(plist->pl_pages.next, struct cl_page, cp_batch);
3058 * Iterate over pages in a page list.
3060 #define cl_page_list_for_each(page, list) \
3061 list_for_each_entry((page), &(list)->pl_pages, cp_batch)
3064 * Iterate over pages in a page list, taking possible removals into account.
3066 #define cl_page_list_for_each_safe(page, temp, list) \
3067 list_for_each_entry_safe((page), (temp), &(list)->pl_pages, cp_batch)
3069 void cl_page_list_init (struct cl_page_list *plist);
3070 void cl_page_list_add (struct cl_page_list *plist, struct cl_page *page);
3071 void cl_page_list_move (struct cl_page_list *dst, struct cl_page_list *src,
3072 struct cl_page *page);
3073 void cl_page_list_move_head(struct cl_page_list *dst, struct cl_page_list *src,
3074 struct cl_page *page);
3075 void cl_page_list_splice (struct cl_page_list *list,
3076 struct cl_page_list *head);
3077 void cl_page_list_del (const struct lu_env *env,
3078 struct cl_page_list *plist, struct cl_page *page);
3079 void cl_page_list_disown (const struct lu_env *env,
3080 struct cl_io *io, struct cl_page_list *plist);
3081 int cl_page_list_own (const struct lu_env *env,
3082 struct cl_io *io, struct cl_page_list *plist);
3083 void cl_page_list_assume (const struct lu_env *env,
3084 struct cl_io *io, struct cl_page_list *plist);
3085 void cl_page_list_discard(const struct lu_env *env,
3086 struct cl_io *io, struct cl_page_list *plist);
3087 void cl_page_list_fini (const struct lu_env *env, struct cl_page_list *plist);
3089 void cl_2queue_init (struct cl_2queue *queue);
3090 void cl_2queue_add (struct cl_2queue *queue, struct cl_page *page);
3091 void cl_2queue_disown (const struct lu_env *env,
3092 struct cl_io *io, struct cl_2queue *queue);
3093 void cl_2queue_assume (const struct lu_env *env,
3094 struct cl_io *io, struct cl_2queue *queue);
3095 void cl_2queue_discard (const struct lu_env *env,
3096 struct cl_io *io, struct cl_2queue *queue);
3097 void cl_2queue_fini (const struct lu_env *env, struct cl_2queue *queue);
3098 void cl_2queue_init_page(struct cl_2queue *queue, struct cl_page *page);
3100 /** @} cl_page_list */
3102 /** \defgroup cl_req cl_req
3104 struct cl_req *cl_req_alloc(const struct lu_env *env, struct cl_page *page,
3105 enum cl_req_type crt, int nr_objects);
3107 void cl_req_page_add (const struct lu_env *env, struct cl_req *req,
3108 struct cl_page *page);
3109 void cl_req_page_done (const struct lu_env *env, struct cl_page *page);
3110 int cl_req_prep (const struct lu_env *env, struct cl_req *req);
3111 void cl_req_attr_set (const struct lu_env *env, struct cl_req *req,
3112 struct cl_req_attr *attr, obd_valid flags);
3113 void cl_req_completion(const struct lu_env *env, struct cl_req *req, int ioret);
3115 /** \defgroup cl_sync_io cl_sync_io
3119 * Anchor for synchronous transfer. This is allocated on a stack by thread
3120 * doing synchronous transfer, and a pointer to this structure is set up in
3121 * every page submitted for transfer. Transfer completion routine updates
3122 * anchor and wakes up waiting thread when transfer is complete.
3125 /** number of pages yet to be transferred. */
3126 atomic_t csi_sync_nr;
3129 /** barrier of destroy this structure */
3130 atomic_t csi_barrier;
3131 /** completion to be signaled when transfer is complete. */
3132 wait_queue_head_t csi_waitq;
3135 void cl_sync_io_init(struct cl_sync_io *anchor, int nrpages);
3136 int cl_sync_io_wait(const struct lu_env *env, struct cl_io *io,
3137 struct cl_page_list *queue, struct cl_sync_io *anchor,
3139 void cl_sync_io_note(struct cl_sync_io *anchor, int ioret);
3141 /** @} cl_sync_io */
3145 /** \defgroup cl_env cl_env
3147 * lu_env handling for a client.
3149 * lu_env is an environment within which lustre code executes. Its major part
3150 * is lu_context---a fast memory allocation mechanism that is used to conserve
3151 * precious kernel stack space. Originally lu_env was designed for a server,
3154 * - there is a (mostly) fixed number of threads, and
3156 * - call chains have no non-lustre portions inserted between lustre code.
3158 * On a client both these assumtpion fails, because every user thread can
3159 * potentially execute lustre code as part of a system call, and lustre calls
3160 * into VFS or MM that call back into lustre.
3162 * To deal with that, cl_env wrapper functions implement the following
3165 * - allocation and destruction of environment is amortized by caching no
3166 * longer used environments instead of destroying them;
3168 * - there is a notion of "current" environment, attached to the kernel
3169 * data structure representing current thread Top-level lustre code
3170 * allocates an environment and makes it current, then calls into
3171 * non-lustre code, that in turn calls lustre back. Low-level lustre
3172 * code thus called can fetch environment created by the top-level code
3173 * and reuse it, avoiding additional environment allocation.
3174 * Right now, three interfaces can attach the cl_env to running thread:
3177 * - cl_env_reexit(cl_env_reenter had to be called priorly)
3179 * \see lu_env, lu_context, lu_context_key
3182 struct cl_env_nest {
3187 struct lu_env *cl_env_peek (int *refcheck);
3188 struct lu_env *cl_env_get (int *refcheck);
3189 struct lu_env *cl_env_alloc (int *refcheck, __u32 tags);
3190 struct lu_env *cl_env_nested_get (struct cl_env_nest *nest);
3191 void cl_env_put (struct lu_env *env, int *refcheck);
3192 void cl_env_nested_put (struct cl_env_nest *nest, struct lu_env *env);
3193 void *cl_env_reenter (void);
3194 void cl_env_reexit (void *cookie);
3195 void cl_env_implant (struct lu_env *env, int *refcheck);
3196 void cl_env_unplant (struct lu_env *env, int *refcheck);
3197 unsigned cl_env_cache_purge(unsigned nr);
3198 struct lu_env *cl_env_percpu_get (void);
3199 void cl_env_percpu_put (struct lu_env *env);
3206 void cl_attr2lvb(struct ost_lvb *lvb, const struct cl_attr *attr);
3207 void cl_lvb2attr(struct cl_attr *attr, const struct ost_lvb *lvb);
3209 struct cl_device *cl_type_setup(const struct lu_env *env, struct lu_site *site,
3210 struct lu_device_type *ldt,
3211 struct lu_device *next);
3214 int cl_global_init(void);
3215 void cl_global_fini(void);
3217 #endif /* _LINUX_CL_OBJECT_H */