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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 <lu_object.h>
102 # include <linux/mutex.h>
103 # include <linux/radix-tree.h>
109 struct cl_device_operations;
112 struct cl_object_page_operations;
113 struct cl_object_lock_operations;
116 struct cl_page_slice;
118 struct cl_lock_slice;
120 struct cl_lock_operations;
121 struct cl_page_operations;
130 * Operations for each data device in the client stack.
132 * \see vvp_cl_ops, lov_cl_ops, lovsub_cl_ops, osc_cl_ops
134 struct cl_device_operations {
136 * Initialize cl_req. This method is called top-to-bottom on all
137 * devices in the stack to get them a chance to allocate layer-private
138 * data, and to attach them to the cl_req by calling
139 * cl_req_slice_add().
141 * \see osc_req_init(), lov_req_init(), lovsub_req_init()
142 * \see ccc_req_init()
144 int (*cdo_req_init)(const struct lu_env *env, struct cl_device *dev,
149 * Device in the client stack.
151 * \see ccc_device, lov_device, lovsub_device, osc_device
155 struct lu_device cd_lu_dev;
156 /** Per-layer operation vector. */
157 const struct cl_device_operations *cd_ops;
160 /** \addtogroup cl_object cl_object
163 * "Data attributes" of cl_object. Data attributes can be updated
164 * independently for a sub-object, and top-object's attributes are calculated
165 * from sub-objects' ones.
168 /** Object size, in bytes */
171 * Known minimal size, in bytes.
173 * This is only valid when at least one DLM lock is held.
176 /** Modification time. Measured in seconds since epoch. */
178 /** Access time. Measured in seconds since epoch. */
180 /** Change time. Measured in seconds since epoch. */
183 * Blocks allocated to this cl_object on the server file system.
185 * \todo XXX An interface for block size is needed.
189 * User identifier for quota purposes.
193 * Group identifier for quota purposes.
199 * Fields in cl_attr that are being set.
213 * Sub-class of lu_object with methods common for objects on the client
216 * cl_object: represents a regular file system object, both a file and a
217 * stripe. cl_object is based on lu_object: it is identified by a fid,
218 * layered, cached, hashed, and lrued. Important distinction with the server
219 * side, where md_object and dt_object are used, is that cl_object "fans out"
220 * at the lov/sns level: depending on the file layout, single file is
221 * represented as a set of "sub-objects" (stripes). At the implementation
222 * level, struct lov_object contains an array of cl_objects. Each sub-object
223 * is a full-fledged cl_object, having its fid, living in the lru and hash
226 * This leads to the next important difference with the server side: on the
227 * client, it's quite usual to have objects with the different sequence of
228 * layers. For example, typical top-object is composed of the following
234 * whereas its sub-objects are composed of
239 * layers. Here "lovsub" is a mostly dummy layer, whose purpose is to keep
240 * track of the object-subobject relationship.
242 * Sub-objects are not cached independently: when top-object is about to
243 * be discarded from the memory, all its sub-objects are torn-down and
246 * \see ccc_object, lov_object, lovsub_object, osc_object
250 struct lu_object co_lu;
251 /** per-object-layer operations */
252 const struct cl_object_operations *co_ops;
253 /** offset of page slice in cl_page buffer */
258 * Description of the client object configuration. This is used for the
259 * creation of a new client object that is identified by a more state than
262 struct cl_object_conf {
264 struct lu_object_conf coc_lu;
267 * Object layout. This is consumed by lov.
269 struct lustre_md *coc_md;
271 * Description of particular stripe location in the
272 * cluster. This is consumed by osc.
274 struct lov_oinfo *coc_oinfo;
277 * VFS inode. This is consumed by vvp.
279 struct inode *coc_inode;
281 * Layout lock handle.
283 struct ldlm_lock *coc_lock;
285 * Operation to handle layout, OBJECT_CONF_XYZ.
291 /** configure layout, set up a new stripe, must be called while
292 * holding layout lock. */
294 /** invalidate the current stripe configuration due to losing
296 OBJECT_CONF_INVALIDATE = 1,
297 /** wait for old layout to go away so that new layout can be
303 * Operations implemented for each cl object layer.
305 * \see vvp_ops, lov_ops, lovsub_ops, osc_ops
307 struct cl_object_operations {
309 * Initialize page slice for this layer. Called top-to-bottom through
310 * every object layer when a new cl_page is instantiated. Layer
311 * keeping private per-page data, or requiring its own page operations
312 * vector should allocate these data here, and attach then to the page
313 * by calling cl_page_slice_add(). \a vmpage is locked (in the VM
316 * \retval NULL success.
318 * \retval ERR_PTR(errno) failure code.
320 * \retval valid-pointer pointer to already existing referenced page
321 * to be used instead of newly created.
323 int (*coo_page_init)(const struct lu_env *env, struct cl_object *obj,
324 struct cl_page *page, struct page *vmpage);
326 * Initialize lock slice for this layer. Called top-to-bottom through
327 * every object layer when a new cl_lock is instantiated. Layer
328 * keeping private per-lock data, or requiring its own lock operations
329 * vector should allocate these data here, and attach then to the lock
330 * by calling cl_lock_slice_add(). Mandatory.
332 int (*coo_lock_init)(const struct lu_env *env,
333 struct cl_object *obj, struct cl_lock *lock,
334 const struct cl_io *io);
336 * Initialize io state for a given layer.
338 * called top-to-bottom once per io existence to initialize io
339 * state. If layer wants to keep some state for this type of io, it
340 * has to embed struct cl_io_slice in lu_env::le_ses, and register
341 * slice with cl_io_slice_add(). It is guaranteed that all threads
342 * participating in this io share the same session.
344 int (*coo_io_init)(const struct lu_env *env,
345 struct cl_object *obj, struct cl_io *io);
347 * Fill portion of \a attr that this layer controls. This method is
348 * called top-to-bottom through all object layers.
350 * \pre cl_object_header::coh_attr_guard of the top-object is locked.
352 * \return 0: to continue
353 * \return +ve: to stop iterating through layers (but 0 is returned
354 * from enclosing cl_object_attr_get())
355 * \return -ve: to signal error
357 int (*coo_attr_get)(const struct lu_env *env, struct cl_object *obj,
358 struct cl_attr *attr);
362 * \a valid is a bitmask composed from enum #cl_attr_valid, and
363 * indicating what attributes are to be set.
365 * \pre cl_object_header::coh_attr_guard of the top-object is locked.
367 * \return the same convention as for
368 * cl_object_operations::coo_attr_get() is used.
370 int (*coo_attr_set)(const struct lu_env *env, struct cl_object *obj,
371 const struct cl_attr *attr, unsigned valid);
373 * Update object configuration. Called top-to-bottom to modify object
376 * XXX error conditions and handling.
378 int (*coo_conf_set)(const struct lu_env *env, struct cl_object *obj,
379 const struct cl_object_conf *conf);
381 * Glimpse ast. Executed when glimpse ast arrives for a lock on this
382 * object. Layers are supposed to fill parts of \a lvb that will be
383 * shipped to the glimpse originator as a glimpse result.
385 * \see ccc_object_glimpse(), lovsub_object_glimpse(),
386 * \see osc_object_glimpse()
388 int (*coo_glimpse)(const struct lu_env *env,
389 const struct cl_object *obj, struct ost_lvb *lvb);
391 * Object prune method. Called when the layout is going to change on
392 * this object, therefore each layer has to clean up their cache,
393 * mainly pages and locks.
395 int (*coo_prune)(const struct lu_env *env, struct cl_object *obj);
399 * Extended header for client object.
401 struct cl_object_header {
402 /** Standard lu_object_header. cl_object::co_lu::lo_header points
404 struct lu_object_header coh_lu;
406 * \todo XXX move locks below to the separate cache-lines, they are
407 * mostly useless otherwise.
410 /** Lock protecting lock list. */
411 spinlock_t coh_lock_guard;
413 /** List of cl_lock's granted for this object. */
414 cfs_list_t coh_locks;
417 * Parent object. It is assumed that an object has a well-defined
418 * parent, but not a well-defined child (there may be multiple
419 * sub-objects, for the same top-object). cl_object_header::coh_parent
420 * field allows certain code to be written generically, without
421 * limiting possible cl_object layouts unduly.
423 struct cl_object_header *coh_parent;
425 * Protects consistency between cl_attr of parent object and
426 * attributes of sub-objects, that the former is calculated ("merged")
429 * \todo XXX this can be read/write lock if needed.
431 spinlock_t coh_attr_guard;
433 * Size of cl_page + page slices
435 unsigned short coh_page_bufsize;
437 * Number of objects above this one: 0 for a top-object, 1 for its
440 unsigned char coh_nesting;
444 * Helper macro: iterate over all layers of the object \a obj, assigning every
445 * layer top-to-bottom to \a slice.
447 #define cl_object_for_each(slice, obj) \
448 cfs_list_for_each_entry((slice), \
449 &(obj)->co_lu.lo_header->loh_layers, \
452 * Helper macro: iterate over all layers of the object \a obj, assigning every
453 * layer bottom-to-top to \a slice.
455 #define cl_object_for_each_reverse(slice, obj) \
456 cfs_list_for_each_entry_reverse((slice), \
457 &(obj)->co_lu.lo_header->loh_layers, \
462 #define pgoff_t unsigned long
465 #define CL_PAGE_EOF ((pgoff_t)~0ull)
467 /** \addtogroup cl_page cl_page
471 * Layered client page.
473 * cl_page: represents a portion of a file, cached in the memory. All pages
474 * of the given file are of the same size, and are kept in the radix tree
475 * hanging off the cl_object. cl_page doesn't fan out, but as sub-objects
476 * of the top-level file object are first class cl_objects, they have their
477 * own radix trees of pages and hence page is implemented as a sequence of
478 * struct cl_pages's, linked into double-linked list through
479 * cl_page::cp_parent and cl_page::cp_child pointers, each residing in the
480 * corresponding radix tree at the corresponding logical offset.
482 * cl_page is associated with VM page of the hosting environment (struct
483 * page in Linux kernel, for example), struct page. It is assumed, that this
484 * association is implemented by one of cl_page layers (top layer in the
485 * current design) that
487 * - intercepts per-VM-page call-backs made by the environment (e.g.,
490 * - translates state (page flag bits) and locking between lustre and
493 * The association between cl_page and struct page is immutable and
494 * established when cl_page is created.
496 * cl_page can be "owned" by a particular cl_io (see below), guaranteeing
497 * this io an exclusive access to this page w.r.t. other io attempts and
498 * various events changing page state (such as transfer completion, or
499 * eviction of the page from the memory). Note, that in general cl_io
500 * cannot be identified with a particular thread, and page ownership is not
501 * exactly equal to the current thread holding a lock on the page. Layer
502 * implementing association between cl_page and struct page has to implement
503 * ownership on top of available synchronization mechanisms.
505 * While lustre client maintains the notion of an page ownership by io,
506 * hosting MM/VM usually has its own page concurrency control
507 * mechanisms. For example, in Linux, page access is synchronized by the
508 * per-page PG_locked bit-lock, and generic kernel code (generic_file_*())
509 * takes care to acquire and release such locks as necessary around the
510 * calls to the file system methods (->readpage(), ->prepare_write(),
511 * ->commit_write(), etc.). This leads to the situation when there are two
512 * different ways to own a page in the client:
514 * - client code explicitly and voluntary owns the page (cl_page_own());
516 * - VM locks a page and then calls the client, that has "to assume"
517 * the ownership from the VM (cl_page_assume()).
519 * Dual methods to release ownership are cl_page_disown() and
520 * cl_page_unassume().
522 * cl_page is reference counted (cl_page::cp_ref). When reference counter
523 * drops to 0, the page is returned to the cache, unless it is in
524 * cl_page_state::CPS_FREEING state, in which case it is immediately
527 * The general logic guaranteeing the absence of "existential races" for
528 * pages is the following:
530 * - there are fixed known ways for a thread to obtain a new reference
533 * - by doing a lookup in the cl_object radix tree, protected by the
536 * - by starting from VM-locked struct page and following some
537 * hosting environment method (e.g., following ->private pointer in
538 * the case of Linux kernel), see cl_vmpage_page();
540 * - when the page enters cl_page_state::CPS_FREEING state, all these
541 * ways are severed with the proper synchronization
542 * (cl_page_delete());
544 * - entry into cl_page_state::CPS_FREEING is serialized by the VM page
547 * - no new references to the page in cl_page_state::CPS_FREEING state
548 * are allowed (checked in cl_page_get()).
550 * Together this guarantees that when last reference to a
551 * cl_page_state::CPS_FREEING page is released, it is safe to destroy the
552 * page, as neither references to it can be acquired at that point, nor
555 * cl_page is a state machine. States are enumerated in enum
556 * cl_page_state. Possible state transitions are enumerated in
557 * cl_page_state_set(). State transition process (i.e., actual changing of
558 * cl_page::cp_state field) is protected by the lock on the underlying VM
561 * Linux Kernel implementation.
563 * Binding between cl_page and struct page (which is a typedef for
564 * struct page) is implemented in the vvp layer. cl_page is attached to the
565 * ->private pointer of the struct page, together with the setting of
566 * PG_private bit in page->flags, and acquiring additional reference on the
567 * struct page (much like struct buffer_head, or any similar file system
568 * private data structures).
570 * PG_locked lock is used to implement both ownership and transfer
571 * synchronization, that is, page is VM-locked in CPS_{OWNED,PAGE{IN,OUT}}
572 * states. No additional references are acquired for the duration of the
575 * \warning *THIS IS NOT* the behavior expected by the Linux kernel, where
576 * write-out is "protected" by the special PG_writeback bit.
580 * States of cl_page. cl_page.c assumes particular order here.
582 * The page state machine is rather crude, as it doesn't recognize finer page
583 * states like "dirty" or "up to date". This is because such states are not
584 * always well defined for the whole stack (see, for example, the
585 * implementation of the read-ahead, that hides page up-to-dateness to track
586 * cache hits accurately). Such sub-states are maintained by the layers that
587 * are interested in them.
591 * Page is in the cache, un-owned. Page leaves cached state in the
594 * - [cl_page_state::CPS_OWNED] io comes across the page and
597 * - [cl_page_state::CPS_PAGEOUT] page is dirty, the
598 * req-formation engine decides that it wants to include this page
599 * into an cl_req being constructed, and yanks it from the cache;
601 * - [cl_page_state::CPS_FREEING] VM callback is executed to
602 * evict the page form the memory;
604 * \invariant cl_page::cp_owner == NULL && cl_page::cp_req == NULL
608 * Page is exclusively owned by some cl_io. Page may end up in this
609 * state as a result of
611 * - io creating new page and immediately owning it;
613 * - [cl_page_state::CPS_CACHED] io finding existing cached page
616 * - [cl_page_state::CPS_OWNED] io finding existing owned page
617 * and waiting for owner to release the page;
619 * Page leaves owned state in the following cases:
621 * - [cl_page_state::CPS_CACHED] io decides to leave the page in
622 * the cache, doing nothing;
624 * - [cl_page_state::CPS_PAGEIN] io starts read transfer for
627 * - [cl_page_state::CPS_PAGEOUT] io starts immediate write
628 * transfer for this page;
630 * - [cl_page_state::CPS_FREEING] io decides to destroy this
631 * page (e.g., as part of truncate or extent lock cancellation).
633 * \invariant cl_page::cp_owner != NULL && cl_page::cp_req == NULL
637 * Page is being written out, as a part of a transfer. This state is
638 * entered when req-formation logic decided that it wants this page to
639 * be sent through the wire _now_. Specifically, it means that once
640 * this state is achieved, transfer completion handler (with either
641 * success or failure indication) is guaranteed to be executed against
642 * this page independently of any locks and any scheduling decisions
643 * made by the hosting environment (that effectively means that the
644 * page is never put into cl_page_state::CPS_PAGEOUT state "in
645 * advance". This property is mentioned, because it is important when
646 * reasoning about possible dead-locks in the system). The page can
647 * enter this state as a result of
649 * - [cl_page_state::CPS_OWNED] an io requesting an immediate
650 * write-out of this page, or
652 * - [cl_page_state::CPS_CACHED] req-forming engine deciding
653 * that it has enough dirty pages cached to issue a "good"
656 * The page leaves cl_page_state::CPS_PAGEOUT state when the transfer
657 * is completed---it is moved into cl_page_state::CPS_CACHED state.
659 * Underlying VM page is locked for the duration of transfer.
661 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL
665 * Page is being read in, as a part of a transfer. This is quite
666 * similar to the cl_page_state::CPS_PAGEOUT state, except that
667 * read-in is always "immediate"---there is no such thing a sudden
668 * construction of read cl_req from cached, presumably not up to date,
671 * Underlying VM page is locked for the duration of transfer.
673 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL
677 * Page is being destroyed. This state is entered when client decides
678 * that page has to be deleted from its host object, as, e.g., a part
681 * Once this state is reached, there is no way to escape it.
683 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req == NULL
690 /** Host page, the page is from the host inode which the cl_page
694 /** Transient page, the transient cl_page is used to bind a cl_page
695 * to vmpage which is not belonging to the same object of cl_page.
696 * it is used in DirectIO, lockless IO and liblustre. */
701 * Flags maintained for every cl_page.
705 * Set when pagein completes. Used for debugging (read completes at
706 * most once for a page).
708 CPF_READ_COMPLETED = 1 << 0
712 * Fields are protected by the lock on struct page, except for atomics and
715 * \invariant Data type invariants are in cl_page_invariant(). Basically:
716 * cl_page::cp_parent and cl_page::cp_child are a well-formed double-linked
717 * list, consistent with the parent/child pointers in the cl_page::cp_obj and
718 * cl_page::cp_owner (when set).
721 /** Reference counter. */
723 /** An object this page is a part of. Immutable after creation. */
724 struct cl_object *cp_obj;
725 /** Logical page index within the object. Immutable after creation. */
727 /** List of slices. Immutable after creation. */
728 cfs_list_t cp_layers;
729 /** Parent page, NULL for top-level page. Immutable after creation. */
730 struct cl_page *cp_parent;
731 /** Lower-layer page. NULL for bottommost page. Immutable after
733 struct cl_page *cp_child;
735 * Page state. This field is const to avoid accidental update, it is
736 * modified only internally within cl_page.c. Protected by a VM lock.
738 const enum cl_page_state cp_state;
739 /** Linkage of pages within group. Protected by cl_page::cp_mutex. */
741 /** Mutex serializing membership of a page in a batch. */
742 struct mutex cp_mutex;
743 /** Linkage of pages within cl_req. */
744 cfs_list_t cp_flight;
745 /** Transfer error. */
749 * Page type. Only CPT_TRANSIENT is used so far. Immutable after
752 enum cl_page_type cp_type;
755 * Owning IO in cl_page_state::CPS_OWNED state. Sub-page can be owned
756 * by sub-io. Protected by a VM lock.
758 struct cl_io *cp_owner;
760 * Debug information, the task is owning the page.
762 struct task_struct *cp_task;
764 * Owning IO request in cl_page_state::CPS_PAGEOUT and
765 * cl_page_state::CPS_PAGEIN states. This field is maintained only in
766 * the top-level pages. Protected by a VM lock.
768 struct cl_req *cp_req;
769 /** List of references to this page, for debugging. */
770 struct lu_ref cp_reference;
771 /** Link to an object, for debugging. */
772 struct lu_ref_link cp_obj_ref;
773 /** Link to a queue, for debugging. */
774 struct lu_ref_link cp_queue_ref;
775 /** Per-page flags from enum cl_page_flags. Protected by a VM lock. */
777 /** Assigned if doing a sync_io */
778 struct cl_sync_io *cp_sync_io;
782 * Per-layer part of cl_page.
784 * \see ccc_page, lov_page, osc_page
786 struct cl_page_slice {
787 struct cl_page *cpl_page;
789 * Object slice corresponding to this page slice. Immutable after
792 struct cl_object *cpl_obj;
793 const struct cl_page_operations *cpl_ops;
794 /** Linkage into cl_page::cp_layers. Immutable after creation. */
795 cfs_list_t cpl_linkage;
799 * Lock mode. For the client extent locks.
801 * \warning: cl_lock_mode_match() assumes particular ordering here.
806 * Mode of a lock that protects no data, and exists only as a
807 * placeholder. This is used for `glimpse' requests. A phantom lock
808 * might get promoted to real lock at some point.
817 * Requested transfer type.
827 * Per-layer page operations.
829 * Methods taking an \a io argument are for the activity happening in the
830 * context of given \a io. Page is assumed to be owned by that io, except for
831 * the obvious cases (like cl_page_operations::cpo_own()).
833 * \see vvp_page_ops, lov_page_ops, osc_page_ops
835 struct cl_page_operations {
837 * cl_page<->struct page methods. Only one layer in the stack has to
838 * implement these. Current code assumes that this functionality is
839 * provided by the topmost layer, see cl_page_disown0() as an example.
843 * \return the underlying VM page. Optional.
845 struct page *(*cpo_vmpage)(const struct lu_env *env,
846 const struct cl_page_slice *slice);
848 * Called when \a io acquires this page into the exclusive
849 * ownership. When this method returns, it is guaranteed that the is
850 * not owned by other io, and no transfer is going on against
854 * \see vvp_page_own(), lov_page_own()
856 int (*cpo_own)(const struct lu_env *env,
857 const struct cl_page_slice *slice,
858 struct cl_io *io, int nonblock);
859 /** Called when ownership it yielded. Optional.
861 * \see cl_page_disown()
862 * \see vvp_page_disown()
864 void (*cpo_disown)(const struct lu_env *env,
865 const struct cl_page_slice *slice, struct cl_io *io);
867 * Called for a page that is already "owned" by \a io from VM point of
870 * \see cl_page_assume()
871 * \see vvp_page_assume(), lov_page_assume()
873 void (*cpo_assume)(const struct lu_env *env,
874 const struct cl_page_slice *slice, struct cl_io *io);
875 /** Dual to cl_page_operations::cpo_assume(). Optional. Called
876 * bottom-to-top when IO releases a page without actually unlocking
879 * \see cl_page_unassume()
880 * \see vvp_page_unassume()
882 void (*cpo_unassume)(const struct lu_env *env,
883 const struct cl_page_slice *slice,
886 * Announces whether the page contains valid data or not by \a uptodate.
888 * \see cl_page_export()
889 * \see vvp_page_export()
891 void (*cpo_export)(const struct lu_env *env,
892 const struct cl_page_slice *slice, int uptodate);
894 * Checks whether underlying VM page is locked (in the suitable
895 * sense). Used for assertions.
897 * \retval -EBUSY: page is protected by a lock of a given mode;
898 * \retval -ENODATA: page is not protected by a lock;
899 * \retval 0: this layer cannot decide. (Should never happen.)
901 int (*cpo_is_vmlocked)(const struct lu_env *env,
902 const struct cl_page_slice *slice);
908 * Called when page is truncated from the object. Optional.
910 * \see cl_page_discard()
911 * \see vvp_page_discard(), osc_page_discard()
913 void (*cpo_discard)(const struct lu_env *env,
914 const struct cl_page_slice *slice,
917 * Called when page is removed from the cache, and is about to being
918 * destroyed. Optional.
920 * \see cl_page_delete()
921 * \see vvp_page_delete(), osc_page_delete()
923 void (*cpo_delete)(const struct lu_env *env,
924 const struct cl_page_slice *slice);
925 /** Destructor. Frees resources and slice itself. */
926 void (*cpo_fini)(const struct lu_env *env,
927 struct cl_page_slice *slice);
930 * Checks whether the page is protected by a cl_lock. This is a
931 * per-layer method, because certain layers have ways to check for the
932 * lock much more efficiently than through the generic locks scan, or
933 * implement locking mechanisms separate from cl_lock, e.g.,
934 * LL_FILE_GROUP_LOCKED in vvp. If \a pending is true, check for locks
935 * being canceled, or scheduled for cancellation as soon as the last
936 * user goes away, too.
938 * \retval -EBUSY: page is protected by a lock of a given mode;
939 * \retval -ENODATA: page is not protected by a lock;
940 * \retval 0: this layer cannot decide.
942 * \see cl_page_is_under_lock()
944 int (*cpo_is_under_lock)(const struct lu_env *env,
945 const struct cl_page_slice *slice,
949 * Optional debugging helper. Prints given page slice.
951 * \see cl_page_print()
953 int (*cpo_print)(const struct lu_env *env,
954 const struct cl_page_slice *slice,
955 void *cookie, lu_printer_t p);
959 * Transfer methods. See comment on cl_req for a description of
960 * transfer formation and life-cycle.
965 * Request type dependent vector of operations.
967 * Transfer operations depend on transfer mode (cl_req_type). To avoid
968 * passing transfer mode to each and every of these methods, and to
969 * avoid branching on request type inside of the methods, separate
970 * methods for cl_req_type:CRT_READ and cl_req_type:CRT_WRITE are
971 * provided. That is, method invocation usually looks like
973 * slice->cp_ops.io[req->crq_type].cpo_method(env, slice, ...);
977 * Called when a page is submitted for a transfer as a part of
980 * \return 0 : page is eligible for submission;
981 * \return -EALREADY : skip this page;
982 * \return -ve : error.
984 * \see cl_page_prep()
986 int (*cpo_prep)(const struct lu_env *env,
987 const struct cl_page_slice *slice,
990 * Completion handler. This is guaranteed to be eventually
991 * fired after cl_page_operations::cpo_prep() or
992 * cl_page_operations::cpo_make_ready() call.
994 * This method can be called in a non-blocking context. It is
995 * guaranteed however, that the page involved and its object
996 * are pinned in memory (and, hence, calling cl_page_put() is
999 * \see cl_page_completion()
1001 void (*cpo_completion)(const struct lu_env *env,
1002 const struct cl_page_slice *slice,
1005 * Called when cached page is about to be added to the
1006 * cl_req as a part of req formation.
1008 * \return 0 : proceed with this page;
1009 * \return -EAGAIN : skip this page;
1010 * \return -ve : error.
1012 * \see cl_page_make_ready()
1014 int (*cpo_make_ready)(const struct lu_env *env,
1015 const struct cl_page_slice *slice);
1018 * Tell transfer engine that only [to, from] part of a page should be
1021 * This is used for immediate transfers.
1023 * \todo XXX this is not very good interface. It would be much better
1024 * if all transfer parameters were supplied as arguments to
1025 * cl_io_operations::cio_submit() call, but it is not clear how to do
1026 * this for page queues.
1028 * \see cl_page_clip()
1030 void (*cpo_clip)(const struct lu_env *env,
1031 const struct cl_page_slice *slice,
1034 * \pre the page was queued for transferring.
1035 * \post page is removed from client's pending list, or -EBUSY
1036 * is returned if it has already been in transferring.
1038 * This is one of seldom page operation which is:
1039 * 0. called from top level;
1040 * 1. don't have vmpage locked;
1041 * 2. every layer should synchronize execution of its ->cpo_cancel()
1042 * with completion handlers. Osc uses client obd lock for this
1043 * purpose. Based on there is no vvp_page_cancel and
1044 * lov_page_cancel(), cpo_cancel is defacto protected by client lock.
1046 * \see osc_page_cancel().
1048 int (*cpo_cancel)(const struct lu_env *env,
1049 const struct cl_page_slice *slice);
1051 * Write out a page by kernel. This is only called by ll_writepage
1054 * \see cl_page_flush()
1056 int (*cpo_flush)(const struct lu_env *env,
1057 const struct cl_page_slice *slice,
1063 * Helper macro, dumping detailed information about \a page into a log.
1065 #define CL_PAGE_DEBUG(mask, env, page, format, ...) \
1067 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1068 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1069 cl_page_print(env, &msgdata, lu_cdebug_printer, page); \
1070 CDEBUG(mask, format , ## __VA_ARGS__); \
1075 * Helper macro, dumping shorter information about \a page into a log.
1077 #define CL_PAGE_HEADER(mask, env, page, format, ...) \
1079 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1080 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1081 cl_page_header_print(env, &msgdata, lu_cdebug_printer, page); \
1082 CDEBUG(mask, format , ## __VA_ARGS__); \
1086 static inline int __page_in_use(const struct cl_page *page, int refc)
1088 if (page->cp_type == CPT_CACHEABLE)
1090 LASSERT(cfs_atomic_read(&page->cp_ref) > 0);
1091 return (cfs_atomic_read(&page->cp_ref) > refc);
1093 #define cl_page_in_use(pg) __page_in_use(pg, 1)
1094 #define cl_page_in_use_noref(pg) __page_in_use(pg, 0)
1098 /** \addtogroup cl_lock cl_lock
1102 * Extent locking on the client.
1106 * The locking model of the new client code is built around
1110 * data-type representing an extent lock on a regular file. cl_lock is a
1111 * layered object (much like cl_object and cl_page), it consists of a header
1112 * (struct cl_lock) and a list of layers (struct cl_lock_slice), linked to
1113 * cl_lock::cll_layers list through cl_lock_slice::cls_linkage.
1115 * All locks for a given object are linked into cl_object_header::coh_locks
1116 * list (protected by cl_object_header::coh_lock_guard spin-lock) through
1117 * cl_lock::cll_linkage. Currently this list is not sorted in any way. We can
1118 * sort it in starting lock offset, or use altogether different data structure
1121 * Typical cl_lock consists of the two layers:
1123 * - vvp_lock (vvp specific data), and
1124 * - lov_lock (lov specific data).
1126 * lov_lock contains an array of sub-locks. Each of these sub-locks is a
1127 * normal cl_lock: it has a header (struct cl_lock) and a list of layers:
1129 * - lovsub_lock, and
1132 * Each sub-lock is associated with a cl_object (representing stripe
1133 * sub-object or the file to which top-level cl_lock is associated to), and is
1134 * linked into that cl_object::coh_locks. In this respect cl_lock is similar to
1135 * cl_object (that at lov layer also fans out into multiple sub-objects), and
1136 * is different from cl_page, that doesn't fan out (there is usually exactly
1137 * one osc_page for every vvp_page). We shall call vvp-lov portion of the lock
1138 * a "top-lock" and its lovsub-osc portion a "sub-lock".
1142 * cl_lock is reference counted. When reference counter drops to 0, lock is
1143 * placed in the cache, except when lock is in CLS_FREEING state. CLS_FREEING
1144 * lock is destroyed when last reference is released. Referencing between
1145 * top-lock and its sub-locks is described in the lov documentation module.
1149 * Also, cl_lock is a state machine. This requires some clarification. One of
1150 * the goals of client IO re-write was to make IO path non-blocking, or at
1151 * least to make it easier to make it non-blocking in the future. Here
1152 * `non-blocking' means that when a system call (read, write, truncate)
1153 * reaches a situation where it has to wait for a communication with the
1154 * server, it should --instead of waiting-- remember its current state and
1155 * switch to some other work. E.g,. instead of waiting for a lock enqueue,
1156 * client should proceed doing IO on the next stripe, etc. Obviously this is
1157 * rather radical redesign, and it is not planned to be fully implemented at
1158 * this time, instead we are putting some infrastructure in place, that would
1159 * make it easier to do asynchronous non-blocking IO easier in the
1160 * future. Specifically, where old locking code goes to sleep (waiting for
1161 * enqueue, for example), new code returns cl_lock_transition::CLO_WAIT. When
1162 * enqueue reply comes, its completion handler signals that lock state-machine
1163 * is ready to transit to the next state. There is some generic code in
1164 * cl_lock.c that sleeps, waiting for these signals. As a result, for users of
1165 * this cl_lock.c code, it looks like locking is done in normal blocking
1166 * fashion, and it the same time it is possible to switch to the non-blocking
1167 * locking (simply by returning cl_lock_transition::CLO_WAIT from cl_lock.c
1170 * For a description of state machine states and transitions see enum
1173 * There are two ways to restrict a set of states which lock might move to:
1175 * - placing a "hold" on a lock guarantees that lock will not be moved
1176 * into cl_lock_state::CLS_FREEING state until hold is released. Hold
1177 * can be only acquired on a lock that is not in
1178 * cl_lock_state::CLS_FREEING. All holds on a lock are counted in
1179 * cl_lock::cll_holds. Hold protects lock from cancellation and
1180 * destruction. Requests to cancel and destroy a lock on hold will be
1181 * recorded, but only honored when last hold on a lock is released;
1183 * - placing a "user" on a lock guarantees that lock will not leave
1184 * cl_lock_state::CLS_NEW, cl_lock_state::CLS_QUEUING,
1185 * cl_lock_state::CLS_ENQUEUED and cl_lock_state::CLS_HELD set of
1186 * states, once it enters this set. That is, if a user is added onto a
1187 * lock in a state not from this set, it doesn't immediately enforce
1188 * lock to move to this set, but once lock enters this set it will
1189 * remain there until all users are removed. Lock users are counted in
1190 * cl_lock::cll_users.
1192 * User is used to assure that lock is not canceled or destroyed while
1193 * it is being enqueued, or actively used by some IO.
1195 * Currently, a user always comes with a hold (cl_lock_invariant()
1196 * checks that a number of holds is not less than a number of users).
1200 * This is how lock state-machine operates. struct cl_lock contains a mutex
1201 * cl_lock::cll_guard that protects struct fields.
1203 * - mutex is taken, and cl_lock::cll_state is examined.
1205 * - for every state there are possible target states where lock can move
1206 * into. They are tried in order. Attempts to move into next state are
1207 * done by _try() functions in cl_lock.c:cl_{enqueue,unlock,wait}_try().
1209 * - if the transition can be performed immediately, state is changed,
1210 * and mutex is released.
1212 * - if the transition requires blocking, _try() function returns
1213 * cl_lock_transition::CLO_WAIT. Caller unlocks mutex and goes to
1214 * sleep, waiting for possibility of lock state change. It is woken
1215 * up when some event occurs, that makes lock state change possible
1216 * (e.g., the reception of the reply from the server), and repeats
1219 * Top-lock and sub-lock has separate mutexes and the latter has to be taken
1220 * first to avoid dead-lock.
1222 * To see an example of interaction of all these issues, take a look at the
1223 * lov_cl.c:lov_lock_enqueue() function. It is called as a part of
1224 * cl_enqueue_try(), and tries to advance top-lock to ENQUEUED state, by
1225 * advancing state-machines of its sub-locks (lov_lock_enqueue_one()). Note
1226 * also, that it uses trylock to grab sub-lock mutex to avoid dead-lock. It
1227 * also has to handle CEF_ASYNC enqueue, when sub-locks enqueues have to be
1228 * done in parallel, rather than one after another (this is used for glimpse
1229 * locks, that cannot dead-lock).
1231 * INTERFACE AND USAGE
1233 * struct cl_lock_operations provide a number of call-backs that are invoked
1234 * when events of interest occurs. Layers can intercept and handle glimpse,
1235 * blocking, cancel ASTs and a reception of the reply from the server.
1237 * One important difference with the old client locking model is that new
1238 * client has a representation for the top-lock, whereas in the old code only
1239 * sub-locks existed as real data structures and file-level locks are
1240 * represented by "request sets" that are created and destroyed on each and
1241 * every lock creation.
1243 * Top-locks are cached, and can be found in the cache by the system calls. It
1244 * is possible that top-lock is in cache, but some of its sub-locks were
1245 * canceled and destroyed. In that case top-lock has to be enqueued again
1246 * before it can be used.
1248 * Overall process of the locking during IO operation is as following:
1250 * - once parameters for IO are setup in cl_io, cl_io_operations::cio_lock()
1251 * is called on each layer. Responsibility of this method is to add locks,
1252 * needed by a given layer into cl_io.ci_lockset.
1254 * - once locks for all layers were collected, they are sorted to avoid
1255 * dead-locks (cl_io_locks_sort()), and enqueued.
1257 * - when all locks are acquired, IO is performed;
1259 * - locks are released into cache.
1261 * Striping introduces major additional complexity into locking. The
1262 * fundamental problem is that it is generally unsafe to actively use (hold)
1263 * two locks on the different OST servers at the same time, as this introduces
1264 * inter-server dependency and can lead to cascading evictions.
1266 * Basic solution is to sub-divide large read/write IOs into smaller pieces so
1267 * that no multi-stripe locks are taken (note that this design abandons POSIX
1268 * read/write semantics). Such pieces ideally can be executed concurrently. At
1269 * the same time, certain types of IO cannot be sub-divived, without
1270 * sacrificing correctness. This includes:
1272 * - O_APPEND write, where [0, EOF] lock has to be taken, to guarantee
1275 * - ftruncate(fd, offset), where [offset, EOF] lock has to be taken.
1277 * Also, in the case of read(fd, buf, count) or write(fd, buf, count), where
1278 * buf is a part of memory mapped Lustre file, a lock or locks protecting buf
1279 * has to be held together with the usual lock on [offset, offset + count].
1281 * As multi-stripe locks have to be allowed, it makes sense to cache them, so
1282 * that, for example, a sequence of O_APPEND writes can proceed quickly
1283 * without going down to the individual stripes to do lock matching. On the
1284 * other hand, multi-stripe locks shouldn't be used by normal read/write
1285 * calls. To achieve this, every layer can implement ->clo_fits_into() method,
1286 * that is called by lock matching code (cl_lock_lookup()), and that can be
1287 * used to selectively disable matching of certain locks for certain IOs. For
1288 * exmaple, lov layer implements lov_lock_fits_into() that allow multi-stripe
1289 * locks to be matched only for truncates and O_APPEND writes.
1291 * Interaction with DLM
1293 * In the expected setup, cl_lock is ultimately backed up by a collection of
1294 * DLM locks (struct ldlm_lock). Association between cl_lock and DLM lock is
1295 * implemented in osc layer, that also matches DLM events (ASTs, cancellation,
1296 * etc.) into cl_lock_operation calls. See struct osc_lock for a more detailed
1297 * description of interaction with DLM.
1303 struct cl_lock_descr {
1304 /** Object this lock is granted for. */
1305 struct cl_object *cld_obj;
1306 /** Index of the first page protected by this lock. */
1308 /** Index of the last page (inclusive) protected by this lock. */
1310 /** Group ID, for group lock */
1313 enum cl_lock_mode cld_mode;
1315 * flags to enqueue lock. A combination of bit-flags from
1316 * enum cl_enq_flags.
1318 __u32 cld_enq_flags;
1321 #define DDESCR "%s(%d):[%lu, %lu]"
1322 #define PDESCR(descr) \
1323 cl_lock_mode_name((descr)->cld_mode), (descr)->cld_mode, \
1324 (descr)->cld_start, (descr)->cld_end
1326 const char *cl_lock_mode_name(const enum cl_lock_mode mode);
1329 * Lock state-machine states.
1334 * Possible state transitions:
1336 * +------------------>NEW
1338 * | | cl_enqueue_try()
1340 * | cl_unuse_try() V
1341 * | +--------------QUEUING (*)
1343 * | | | cl_enqueue_try()
1345 * | | cl_unuse_try() V
1346 * sub-lock | +-------------ENQUEUED (*)
1348 * | | | cl_wait_try()
1353 * | | HELD<---------+
1355 * | | | | cl_use_try()
1356 * | | cl_unuse_try() | |
1359 * | +------------>INTRANSIT (D) <--+
1361 * | cl_unuse_try() | | cached lock found
1362 * | | | cl_use_try()
1365 * +------------------CACHED---------+
1374 * In states marked with (*) transition to the same state (i.e., a loop
1375 * in the diagram) is possible.
1377 * (R) is the point where Receive call-back is invoked: it allows layers
1378 * to handle arrival of lock reply.
1380 * (C) is the point where Cancellation call-back is invoked.
1382 * (D) is the transit state which means the lock is changing.
1384 * Transition to FREEING state is possible from any other state in the
1385 * diagram in case of unrecoverable error.
1389 * These states are for individual cl_lock object. Top-lock and its sub-locks
1390 * can be in the different states. Another way to say this is that we have
1391 * nested state-machines.
1393 * Separate QUEUING and ENQUEUED states are needed to support non-blocking
1394 * operation for locks with multiple sub-locks. Imagine lock on a file F, that
1395 * intersects 3 stripes S0, S1, and S2. To enqueue F client has to send
1396 * enqueue to S0, wait for its completion, then send enqueue for S1, wait for
1397 * its completion and at last enqueue lock for S2, and wait for its
1398 * completion. In that case, top-lock is in QUEUING state while S0, S1 are
1399 * handled, and is in ENQUEUED state after enqueue to S2 has been sent (note
1400 * that in this case, sub-locks move from state to state, and top-lock remains
1401 * in the same state).
1403 enum cl_lock_state {
1405 * Lock that wasn't yet enqueued
1409 * Enqueue is in progress, blocking for some intermediate interaction
1410 * with the other side.
1414 * Lock is fully enqueued, waiting for server to reply when it is
1419 * Lock granted, actively used by some IO.
1423 * This state is used to mark the lock is being used, or unused.
1424 * We need this state because the lock may have several sublocks,
1425 * so it's impossible to have an atomic way to bring all sublocks
1426 * into CLS_HELD state at use case, or all sublocks to CLS_CACHED
1428 * If a thread is referring to a lock, and it sees the lock is in this
1429 * state, it must wait for the lock.
1430 * See state diagram for details.
1434 * Lock granted, not used.
1438 * Lock is being destroyed.
1444 enum cl_lock_flags {
1446 * lock has been cancelled. This flag is never cleared once set (by
1447 * cl_lock_cancel0()).
1449 CLF_CANCELLED = 1 << 0,
1450 /** cancellation is pending for this lock. */
1451 CLF_CANCELPEND = 1 << 1,
1452 /** destruction is pending for this lock. */
1453 CLF_DOOMED = 1 << 2,
1454 /** from enqueue RPC reply upcall. */
1455 CLF_FROM_UPCALL= 1 << 3,
1461 * Lock closure is a collection of locks (both top-locks and sub-locks) that
1462 * might be updated in a result of an operation on a certain lock (which lock
1463 * this is a closure of).
1465 * Closures are needed to guarantee dead-lock freedom in the presence of
1467 * - nested state-machines (top-lock state-machine composed of sub-lock
1468 * state-machines), and
1470 * - shared sub-locks.
1472 * Specifically, many operations, such as lock enqueue, wait, unlock,
1473 * etc. start from a top-lock, and then operate on a sub-locks of this
1474 * top-lock, holding a top-lock mutex. When sub-lock state changes as a result
1475 * of such operation, this change has to be propagated to all top-locks that
1476 * share this sub-lock. Obviously, no natural lock ordering (e.g.,
1477 * top-to-bottom or bottom-to-top) captures this scenario, so try-locking has
1478 * to be used. Lock closure systematizes this try-and-repeat logic.
1480 struct cl_lock_closure {
1482 * Lock that is mutexed when closure construction is started. When
1483 * closure in is `wait' mode (cl_lock_closure::clc_wait), mutex on
1484 * origin is released before waiting.
1486 struct cl_lock *clc_origin;
1488 * List of enclosed locks, so far. Locks are linked here through
1489 * cl_lock::cll_inclosure.
1491 cfs_list_t clc_list;
1493 * True iff closure is in a `wait' mode. This determines what
1494 * cl_lock_enclosure() does when a lock L to be added to the closure
1495 * is currently mutexed by some other thread.
1497 * If cl_lock_closure::clc_wait is not set, then closure construction
1498 * fails with CLO_REPEAT immediately.
1500 * In wait mode, cl_lock_enclosure() waits until next attempt to build
1501 * a closure might succeed. To this end it releases an origin mutex
1502 * (cl_lock_closure::clc_origin), that has to be the only lock mutex
1503 * owned by the current thread, and then waits on L mutex (by grabbing
1504 * it and immediately releasing), before returning CLO_REPEAT to the
1508 /** Number of locks in the closure. */
1513 * Layered client lock.
1516 /** Reference counter. */
1517 cfs_atomic_t cll_ref;
1518 /** List of slices. Immutable after creation. */
1519 cfs_list_t cll_layers;
1521 * Linkage into cl_lock::cll_descr::cld_obj::coh_locks list. Protected
1522 * by cl_lock::cll_descr::cld_obj::coh_lock_guard.
1524 cfs_list_t cll_linkage;
1526 * Parameters of this lock. Protected by
1527 * cl_lock::cll_descr::cld_obj::coh_lock_guard nested within
1528 * cl_lock::cll_guard. Modified only on lock creation and in
1531 struct cl_lock_descr cll_descr;
1532 /** Protected by cl_lock::cll_guard. */
1533 enum cl_lock_state cll_state;
1534 /** signals state changes. */
1535 wait_queue_head_t cll_wq;
1537 * Recursive lock, most fields in cl_lock{} are protected by this.
1539 * Locking rules: this mutex is never held across network
1540 * communication, except when lock is being canceled.
1542 * Lock ordering: a mutex of a sub-lock is taken first, then a mutex
1543 * on a top-lock. Other direction is implemented through a
1544 * try-lock-repeat loop. Mutices of unrelated locks can be taken only
1547 * \see osc_lock_enqueue_wait(), lov_lock_cancel(), lov_sublock_wait().
1549 struct mutex cll_guard;
1550 struct task_struct *cll_guarder;
1554 * the owner for INTRANSIT state
1556 struct task_struct *cll_intransit_owner;
1559 * Number of holds on a lock. A hold prevents a lock from being
1560 * canceled and destroyed. Protected by cl_lock::cll_guard.
1562 * \see cl_lock_hold(), cl_lock_unhold(), cl_lock_release()
1566 * Number of lock users. Valid in cl_lock_state::CLS_HELD state
1567 * only. Lock user pins lock in CLS_HELD state. Protected by
1568 * cl_lock::cll_guard.
1570 * \see cl_wait(), cl_unuse().
1574 * Flag bit-mask. Values from enum cl_lock_flags. Updates are
1575 * protected by cl_lock::cll_guard.
1577 unsigned long cll_flags;
1579 * A linkage into a list of locks in a closure.
1581 * \see cl_lock_closure
1583 cfs_list_t cll_inclosure;
1585 * Confict lock at queuing time.
1587 struct cl_lock *cll_conflict;
1589 * A list of references to this lock, for debugging.
1591 struct lu_ref cll_reference;
1593 * A list of holds on this lock, for debugging.
1595 struct lu_ref cll_holders;
1597 * A reference for cl_lock::cll_descr::cld_obj. For debugging.
1599 struct lu_ref_link cll_obj_ref;
1600 #ifdef CONFIG_LOCKDEP
1601 /* "dep_map" name is assumed by lockdep.h macros. */
1602 struct lockdep_map dep_map;
1607 * Per-layer part of cl_lock
1609 * \see ccc_lock, lov_lock, lovsub_lock, osc_lock
1611 struct cl_lock_slice {
1612 struct cl_lock *cls_lock;
1613 /** Object slice corresponding to this lock slice. Immutable after
1615 struct cl_object *cls_obj;
1616 const struct cl_lock_operations *cls_ops;
1617 /** Linkage into cl_lock::cll_layers. Immutable after creation. */
1618 cfs_list_t cls_linkage;
1622 * Possible (non-error) return values of ->clo_{enqueue,wait,unlock}().
1624 * NOTE: lov_subresult() depends on ordering here.
1626 enum cl_lock_transition {
1627 /** operation cannot be completed immediately. Wait for state change. */
1629 /** operation had to release lock mutex, restart. */
1631 /** lower layer re-enqueued. */
1637 * \see vvp_lock_ops, lov_lock_ops, lovsub_lock_ops, osc_lock_ops
1639 struct cl_lock_operations {
1641 * \name statemachine
1643 * State machine transitions. These 3 methods are called to transfer
1644 * lock from one state to another, as described in the commentary
1645 * above enum #cl_lock_state.
1647 * \retval 0 this layer has nothing more to do to before
1648 * transition to the target state happens;
1650 * \retval CLO_REPEAT method had to release and re-acquire cl_lock
1651 * mutex, repeat invocation of transition method
1652 * across all layers;
1654 * \retval CLO_WAIT this layer cannot move to the target state
1655 * immediately, as it has to wait for certain event
1656 * (e.g., the communication with the server). It
1657 * is guaranteed, that when the state transfer
1658 * becomes possible, cl_lock::cll_wq wait-queue
1659 * is signaled. Caller can wait for this event by
1660 * calling cl_lock_state_wait();
1662 * \retval -ve failure, abort state transition, move the lock
1663 * into cl_lock_state::CLS_FREEING state, and set
1664 * cl_lock::cll_error.
1666 * Once all layers voted to agree to transition (by returning 0), lock
1667 * is moved into corresponding target state. All state transition
1668 * methods are optional.
1672 * Attempts to enqueue the lock. Called top-to-bottom.
1674 * \see ccc_lock_enqueue(), lov_lock_enqueue(), lovsub_lock_enqueue(),
1675 * \see osc_lock_enqueue()
1677 int (*clo_enqueue)(const struct lu_env *env,
1678 const struct cl_lock_slice *slice,
1679 struct cl_io *io, __u32 enqflags);
1681 * Attempts to wait for enqueue result. Called top-to-bottom.
1683 * \see ccc_lock_wait(), lov_lock_wait(), osc_lock_wait()
1685 int (*clo_wait)(const struct lu_env *env,
1686 const struct cl_lock_slice *slice);
1688 * Attempts to unlock the lock. Called bottom-to-top. In addition to
1689 * usual return values of lock state-machine methods, this can return
1690 * -ESTALE to indicate that lock cannot be returned to the cache, and
1691 * has to be re-initialized.
1692 * unuse is a one-shot operation, so it must NOT return CLO_WAIT.
1694 * \see ccc_lock_unuse(), lov_lock_unuse(), osc_lock_unuse()
1696 int (*clo_unuse)(const struct lu_env *env,
1697 const struct cl_lock_slice *slice);
1699 * Notifies layer that cached lock is started being used.
1701 * \pre lock->cll_state == CLS_CACHED
1703 * \see lov_lock_use(), osc_lock_use()
1705 int (*clo_use)(const struct lu_env *env,
1706 const struct cl_lock_slice *slice);
1707 /** @} statemachine */
1709 * A method invoked when lock state is changed (as a result of state
1710 * transition). This is used, for example, to track when the state of
1711 * a sub-lock changes, to propagate this change to the corresponding
1712 * top-lock. Optional
1714 * \see lovsub_lock_state()
1716 void (*clo_state)(const struct lu_env *env,
1717 const struct cl_lock_slice *slice,
1718 enum cl_lock_state st);
1720 * Returns true, iff given lock is suitable for the given io, idea
1721 * being, that there are certain "unsafe" locks, e.g., ones acquired
1722 * for O_APPEND writes, that we don't want to re-use for a normal
1723 * write, to avoid the danger of cascading evictions. Optional. Runs
1724 * under cl_object_header::coh_lock_guard.
1726 * XXX this should take more information about lock needed by
1727 * io. Probably lock description or something similar.
1729 * \see lov_fits_into()
1731 int (*clo_fits_into)(const struct lu_env *env,
1732 const struct cl_lock_slice *slice,
1733 const struct cl_lock_descr *need,
1734 const struct cl_io *io);
1737 * Asynchronous System Traps. All of then are optional, all are
1738 * executed bottom-to-top.
1743 * Cancellation callback. Cancel a lock voluntarily, or under
1744 * the request of server.
1746 void (*clo_cancel)(const struct lu_env *env,
1747 const struct cl_lock_slice *slice);
1749 * Lock weighting ast. Executed to estimate how precious this lock
1750 * is. The sum of results across all layers is used to determine
1751 * whether lock worth keeping in cache given present memory usage.
1753 * \see osc_lock_weigh(), vvp_lock_weigh(), lovsub_lock_weigh().
1755 unsigned long (*clo_weigh)(const struct lu_env *env,
1756 const struct cl_lock_slice *slice);
1760 * \see lovsub_lock_closure()
1762 int (*clo_closure)(const struct lu_env *env,
1763 const struct cl_lock_slice *slice,
1764 struct cl_lock_closure *closure);
1766 * Executed bottom-to-top when lock description changes (e.g., as a
1767 * result of server granting more generous lock than was requested).
1769 * \see lovsub_lock_modify()
1771 int (*clo_modify)(const struct lu_env *env,
1772 const struct cl_lock_slice *slice,
1773 const struct cl_lock_descr *updated);
1775 * Notifies layers (bottom-to-top) that lock is going to be
1776 * destroyed. Responsibility of layers is to prevent new references on
1777 * this lock from being acquired once this method returns.
1779 * This can be called multiple times due to the races.
1781 * \see cl_lock_delete()
1782 * \see osc_lock_delete(), lovsub_lock_delete()
1784 void (*clo_delete)(const struct lu_env *env,
1785 const struct cl_lock_slice *slice);
1787 * Destructor. Frees resources and the slice.
1789 * \see ccc_lock_fini(), lov_lock_fini(), lovsub_lock_fini(),
1790 * \see osc_lock_fini()
1792 void (*clo_fini)(const struct lu_env *env, struct cl_lock_slice *slice);
1794 * Optional debugging helper. Prints given lock slice.
1796 int (*clo_print)(const struct lu_env *env,
1797 void *cookie, lu_printer_t p,
1798 const struct cl_lock_slice *slice);
1801 #define CL_LOCK_DEBUG(mask, env, lock, format, ...) \
1803 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1804 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1805 cl_lock_print(env, &msgdata, lu_cdebug_printer, lock); \
1806 CDEBUG(mask, format , ## __VA_ARGS__); \
1810 #define CL_LOCK_ASSERT(expr, env, lock) do { \
1814 CL_LOCK_DEBUG(D_ERROR, env, lock, "failed at %s.\n", #expr); \
1820 /** \addtogroup cl_page_list cl_page_list
1821 * Page list used to perform collective operations on a group of pages.
1823 * Pages are added to the list one by one. cl_page_list acquires a reference
1824 * for every page in it. Page list is used to perform collective operations on
1827 * - submit pages for an immediate transfer,
1829 * - own pages on behalf of certain io (waiting for each page in turn),
1833 * When list is finalized, it releases references on all pages it still has.
1835 * \todo XXX concurrency control.
1839 struct cl_page_list {
1841 cfs_list_t pl_pages;
1842 struct task_struct *pl_owner;
1846 * A 2-queue of pages. A convenience data-type for common use case, 2-queue
1847 * contains an incoming page list and an outgoing page list.
1850 struct cl_page_list c2_qin;
1851 struct cl_page_list c2_qout;
1854 /** @} cl_page_list */
1856 /** \addtogroup cl_io cl_io
1861 * cl_io represents a high level I/O activity like
1862 * read(2)/write(2)/truncate(2) system call, or cancellation of an extent
1865 * cl_io is a layered object, much like cl_{object,page,lock} but with one
1866 * important distinction. We want to minimize number of calls to the allocator
1867 * in the fast path, e.g., in the case of read(2) when everything is cached:
1868 * client already owns the lock over region being read, and data are cached
1869 * due to read-ahead. To avoid allocation of cl_io layers in such situations,
1870 * per-layer io state is stored in the session, associated with the io, see
1871 * struct {vvp,lov,osc}_io for example. Sessions allocation is amortized
1872 * by using free-lists, see cl_env_get().
1874 * There is a small predefined number of possible io types, enumerated in enum
1877 * cl_io is a state machine, that can be advanced concurrently by the multiple
1878 * threads. It is up to these threads to control the concurrency and,
1879 * specifically, to detect when io is done, and its state can be safely
1882 * For read/write io overall execution plan is as following:
1884 * (0) initialize io state through all layers;
1886 * (1) loop: prepare chunk of work to do
1888 * (2) call all layers to collect locks they need to process current chunk
1890 * (3) sort all locks to avoid dead-locks, and acquire them
1892 * (4) process the chunk: call per-page methods
1893 * (cl_io_operations::cio_read_page() for read,
1894 * cl_io_operations::cio_prepare_write(),
1895 * cl_io_operations::cio_commit_write() for write)
1901 * To implement the "parallel IO mode", lov layer creates sub-io's (lazily to
1902 * address allocation efficiency issues mentioned above), and returns with the
1903 * special error condition from per-page method when current sub-io has to
1904 * block. This causes io loop to be repeated, and lov switches to the next
1905 * sub-io in its cl_io_operations::cio_iter_init() implementation.
1910 /** read system call */
1912 /** write system call */
1914 /** truncate, utime system calls */
1917 * page fault handling
1921 * fsync system call handling
1922 * To write out a range of file
1926 * Miscellaneous io. This is used for occasional io activity that
1927 * doesn't fit into other types. Currently this is used for:
1929 * - cancellation of an extent lock. This io exists as a context
1930 * to write dirty pages from under the lock being canceled back
1933 * - VM induced page write-out. An io context for writing page out
1934 * for memory cleansing;
1936 * - glimpse. An io context to acquire glimpse lock.
1938 * - grouplock. An io context to acquire group lock.
1940 * CIT_MISC io is used simply as a context in which locks and pages
1941 * are manipulated. Such io has no internal "process", that is,
1942 * cl_io_loop() is never called for it.
1949 * States of cl_io state machine
1952 /** Not initialized. */
1956 /** IO iteration started. */
1960 /** Actual IO is in progress. */
1962 /** IO for the current iteration finished. */
1964 /** Locks released. */
1966 /** Iteration completed. */
1968 /** cl_io finalized. */
1973 * IO state private for a layer.
1975 * This is usually embedded into layer session data, rather than allocated
1978 * \see vvp_io, lov_io, osc_io, ccc_io
1980 struct cl_io_slice {
1981 struct cl_io *cis_io;
1982 /** corresponding object slice. Immutable after creation. */
1983 struct cl_object *cis_obj;
1984 /** io operations. Immutable after creation. */
1985 const struct cl_io_operations *cis_iop;
1987 * linkage into a list of all slices for a given cl_io, hanging off
1988 * cl_io::ci_layers. Immutable after creation.
1990 cfs_list_t cis_linkage;
1993 typedef void (*cl_commit_cbt)(const struct lu_env *, struct cl_io *,
1997 * Per-layer io operations.
1998 * \see vvp_io_ops, lov_io_ops, lovsub_io_ops, osc_io_ops
2000 struct cl_io_operations {
2002 * Vector of io state transition methods for every io type.
2004 * \see cl_page_operations::io
2008 * Prepare io iteration at a given layer.
2010 * Called top-to-bottom at the beginning of each iteration of
2011 * "io loop" (if it makes sense for this type of io). Here
2012 * layer selects what work it will do during this iteration.
2014 * \see cl_io_operations::cio_iter_fini()
2016 int (*cio_iter_init) (const struct lu_env *env,
2017 const struct cl_io_slice *slice);
2019 * Finalize io iteration.
2021 * Called bottom-to-top at the end of each iteration of "io
2022 * loop". Here layers can decide whether IO has to be
2025 * \see cl_io_operations::cio_iter_init()
2027 void (*cio_iter_fini) (const struct lu_env *env,
2028 const struct cl_io_slice *slice);
2030 * Collect locks for the current iteration of io.
2032 * Called top-to-bottom to collect all locks necessary for
2033 * this iteration. This methods shouldn't actually enqueue
2034 * anything, instead it should post a lock through
2035 * cl_io_lock_add(). Once all locks are collected, they are
2036 * sorted and enqueued in the proper order.
2038 int (*cio_lock) (const struct lu_env *env,
2039 const struct cl_io_slice *slice);
2041 * Finalize unlocking.
2043 * Called bottom-to-top to finish layer specific unlocking
2044 * functionality, after generic code released all locks
2045 * acquired by cl_io_operations::cio_lock().
2047 void (*cio_unlock)(const struct lu_env *env,
2048 const struct cl_io_slice *slice);
2050 * Start io iteration.
2052 * Once all locks are acquired, called top-to-bottom to
2053 * commence actual IO. In the current implementation,
2054 * top-level vvp_io_{read,write}_start() does all the work
2055 * synchronously by calling generic_file_*(), so other layers
2056 * are called when everything is done.
2058 int (*cio_start)(const struct lu_env *env,
2059 const struct cl_io_slice *slice);
2061 * Called top-to-bottom at the end of io loop. Here layer
2062 * might wait for an unfinished asynchronous io.
2064 void (*cio_end) (const struct lu_env *env,
2065 const struct cl_io_slice *slice);
2067 * Called bottom-to-top to notify layers that read/write IO
2068 * iteration finished, with \a nob bytes transferred.
2070 void (*cio_advance)(const struct lu_env *env,
2071 const struct cl_io_slice *slice,
2074 * Called once per io, bottom-to-top to release io resources.
2076 void (*cio_fini) (const struct lu_env *env,
2077 const struct cl_io_slice *slice);
2081 * Submit pages from \a queue->c2_qin for IO, and move
2082 * successfully submitted pages into \a queue->c2_qout. Return
2083 * non-zero if failed to submit even the single page. If
2084 * submission failed after some pages were moved into \a
2085 * queue->c2_qout, completion callback with non-zero ioret is
2088 int (*cio_submit)(const struct lu_env *env,
2089 const struct cl_io_slice *slice,
2090 enum cl_req_type crt,
2091 struct cl_2queue *queue);
2093 * Queue async page for write.
2094 * The difference between cio_submit and cio_queue is that
2095 * cio_submit is for urgent request.
2097 int (*cio_commit_async)(const struct lu_env *env,
2098 const struct cl_io_slice *slice,
2099 struct cl_page_list *queue, int from, int to,
2102 * Read missing page.
2104 * Called by a top-level cl_io_operations::op[CIT_READ]::cio_start()
2105 * method, when it hits not-up-to-date page in the range. Optional.
2107 * \pre io->ci_type == CIT_READ
2109 int (*cio_read_page)(const struct lu_env *env,
2110 const struct cl_io_slice *slice,
2111 const struct cl_page_slice *page);
2113 * Optional debugging helper. Print given io slice.
2115 int (*cio_print)(const struct lu_env *env, void *cookie,
2116 lu_printer_t p, const struct cl_io_slice *slice);
2120 * Flags to lock enqueue procedure.
2125 * instruct server to not block, if conflicting lock is found. Instead
2126 * -EWOULDBLOCK is returned immediately.
2128 CEF_NONBLOCK = 0x00000001,
2130 * take lock asynchronously (out of order), as it cannot
2131 * deadlock. This is for LDLM_FL_HAS_INTENT locks used for glimpsing.
2133 CEF_ASYNC = 0x00000002,
2135 * tell the server to instruct (though a flag in the blocking ast) an
2136 * owner of the conflicting lock, that it can drop dirty pages
2137 * protected by this lock, without sending them to the server.
2139 CEF_DISCARD_DATA = 0x00000004,
2141 * tell the sub layers that it must be a `real' lock. This is used for
2142 * mmapped-buffer locks and glimpse locks that must be never converted
2143 * into lockless mode.
2145 * \see vvp_mmap_locks(), cl_glimpse_lock().
2147 CEF_MUST = 0x00000008,
2149 * tell the sub layers that never request a `real' lock. This flag is
2150 * not used currently.
2152 * cl_io::ci_lockreq and CEF_{MUST,NEVER} flags specify lockless
2153 * conversion policy: ci_lockreq describes generic information of lock
2154 * requirement for this IO, especially for locks which belong to the
2155 * object doing IO; however, lock itself may have precise requirements
2156 * that are described by the enqueue flags.
2158 CEF_NEVER = 0x00000010,
2160 * for async glimpse lock.
2162 CEF_AGL = 0x00000020,
2164 * mask of enq_flags.
2166 CEF_MASK = 0x0000003f,
2170 * Link between lock and io. Intermediate structure is needed, because the
2171 * same lock can be part of multiple io's simultaneously.
2173 struct cl_io_lock_link {
2174 /** linkage into one of cl_lockset lists. */
2175 cfs_list_t cill_linkage;
2176 struct cl_lock_descr cill_descr;
2177 struct cl_lock *cill_lock;
2178 /** optional destructor */
2179 void (*cill_fini)(const struct lu_env *env,
2180 struct cl_io_lock_link *link);
2184 * Lock-set represents a collection of locks, that io needs at a
2185 * time. Generally speaking, client tries to avoid holding multiple locks when
2188 * - holding extent locks over multiple ost's introduces the danger of
2189 * "cascading timeouts";
2191 * - holding multiple locks over the same ost is still dead-lock prone,
2192 * see comment in osc_lock_enqueue(),
2194 * but there are certain situations where this is unavoidable:
2196 * - O_APPEND writes have to take [0, EOF] lock for correctness;
2198 * - truncate has to take [new-size, EOF] lock for correctness;
2200 * - SNS has to take locks across full stripe for correctness;
2202 * - in the case when user level buffer, supplied to {read,write}(file0),
2203 * is a part of a memory mapped lustre file, client has to take a dlm
2204 * locks on file0, and all files that back up the buffer (or a part of
2205 * the buffer, that is being processed in the current chunk, in any
2206 * case, there are situations where at least 2 locks are necessary).
2208 * In such cases we at least try to take locks in the same consistent
2209 * order. To this end, all locks are first collected, then sorted, and then
2213 /** locks to be acquired. */
2214 cfs_list_t cls_todo;
2215 /** locks currently being processed. */
2216 cfs_list_t cls_curr;
2217 /** locks acquired. */
2218 cfs_list_t cls_done;
2222 * Lock requirements(demand) for IO. It should be cl_io_lock_req,
2223 * but 'req' is always to be thought as 'request' :-)
2225 enum cl_io_lock_dmd {
2226 /** Always lock data (e.g., O_APPEND). */
2228 /** Layers are free to decide between local and global locking. */
2230 /** Never lock: there is no cache (e.g., liblustre). */
2234 enum cl_fsync_mode {
2235 /** start writeback, do not wait for them to finish */
2237 /** start writeback and wait for them to finish */
2239 /** discard all of dirty pages in a specific file range */
2240 CL_FSYNC_DISCARD = 2,
2241 /** start writeback and make sure they have reached storage before
2242 * return. OST_SYNC RPC must be issued and finished */
2246 struct cl_io_rw_common {
2256 * cl_io is shared by all threads participating in this IO (in current
2257 * implementation only one thread advances IO, but parallel IO design and
2258 * concurrent copy_*_user() require multiple threads acting on the same IO. It
2259 * is up to these threads to serialize their activities, including updates to
2260 * mutable cl_io fields.
2263 /** type of this IO. Immutable after creation. */
2264 enum cl_io_type ci_type;
2265 /** current state of cl_io state machine. */
2266 enum cl_io_state ci_state;
2267 /** main object this io is against. Immutable after creation. */
2268 struct cl_object *ci_obj;
2270 * Upper layer io, of which this io is a part of. Immutable after
2273 struct cl_io *ci_parent;
2274 /** List of slices. Immutable after creation. */
2275 cfs_list_t ci_layers;
2276 /** list of locks (to be) acquired by this io. */
2277 struct cl_lockset ci_lockset;
2278 /** lock requirements, this is just a help info for sublayers. */
2279 enum cl_io_lock_dmd ci_lockreq;
2282 struct cl_io_rw_common rd;
2285 struct cl_io_rw_common wr;
2289 struct cl_io_rw_common ci_rw;
2290 struct cl_setattr_io {
2291 struct ost_lvb sa_attr;
2292 unsigned int sa_valid;
2293 struct obd_capa *sa_capa;
2295 struct cl_fault_io {
2296 /** page index within file. */
2298 /** bytes valid byte on a faulted page. */
2300 /** writable page? for nopage() only */
2302 /** page of an executable? */
2304 /** page_mkwrite() */
2306 /** resulting page */
2307 struct cl_page *ft_page;
2309 struct cl_fsync_io {
2312 struct obd_capa *fi_capa;
2313 /** file system level fid */
2314 struct lu_fid *fi_fid;
2315 enum cl_fsync_mode fi_mode;
2316 /* how many pages were written/discarded */
2317 unsigned int fi_nr_written;
2320 struct cl_2queue ci_queue;
2323 unsigned int ci_continue:1,
2325 * This io has held grouplock, to inform sublayers that
2326 * don't do lockless i/o.
2330 * The whole IO need to be restarted because layout has been changed
2334 * to not refresh layout - the IO issuer knows that the layout won't
2335 * change(page operations, layout change causes all page to be
2336 * discarded), or it doesn't matter if it changes(sync).
2340 * Check if layout changed after the IO finishes. Mainly for HSM
2341 * requirement. If IO occurs to openning files, it doesn't need to
2342 * verify layout because HSM won't release openning files.
2343 * Right now, only two opertaions need to verify layout: glimpse
2348 * file is released, restore has to to be triggered by vvp layer
2350 ci_restore_needed:1,
2356 * Number of pages owned by this IO. For invariant checking.
2358 unsigned ci_owned_nr;
2363 /** \addtogroup cl_req cl_req
2368 * There are two possible modes of transfer initiation on the client:
2370 * - immediate transfer: this is started when a high level io wants a page
2371 * or a collection of pages to be transferred right away. Examples:
2372 * read-ahead, synchronous read in the case of non-page aligned write,
2373 * page write-out as a part of extent lock cancellation, page write-out
2374 * as a part of memory cleansing. Immediate transfer can be both
2375 * cl_req_type::CRT_READ and cl_req_type::CRT_WRITE;
2377 * - opportunistic transfer (cl_req_type::CRT_WRITE only), that happens
2378 * when io wants to transfer a page to the server some time later, when
2379 * it can be done efficiently. Example: pages dirtied by the write(2)
2382 * In any case, transfer takes place in the form of a cl_req, which is a
2383 * representation for a network RPC.
2385 * Pages queued for an opportunistic transfer are cached until it is decided
2386 * that efficient RPC can be composed of them. This decision is made by "a
2387 * req-formation engine", currently implemented as a part of osc
2388 * layer. Req-formation depends on many factors: the size of the resulting
2389 * RPC, whether or not multi-object RPCs are supported by the server,
2390 * max-rpc-in-flight limitations, size of the dirty cache, etc.
2392 * For the immediate transfer io submits a cl_page_list, that req-formation
2393 * engine slices into cl_req's, possibly adding cached pages to some of
2394 * the resulting req's.
2396 * Whenever a page from cl_page_list is added to a newly constructed req, its
2397 * cl_page_operations::cpo_prep() layer methods are called. At that moment,
2398 * page state is atomically changed from cl_page_state::CPS_OWNED to
2399 * cl_page_state::CPS_PAGEOUT or cl_page_state::CPS_PAGEIN, cl_page::cp_owner
2400 * is zeroed, and cl_page::cp_req is set to the
2401 * req. cl_page_operations::cpo_prep() method at the particular layer might
2402 * return -EALREADY to indicate that it does not need to submit this page
2403 * at all. This is possible, for example, if page, submitted for read,
2404 * became up-to-date in the meantime; and for write, the page don't have
2405 * dirty bit marked. \see cl_io_submit_rw()
2407 * Whenever a cached page is added to a newly constructed req, its
2408 * cl_page_operations::cpo_make_ready() layer methods are called. At that
2409 * moment, page state is atomically changed from cl_page_state::CPS_CACHED to
2410 * cl_page_state::CPS_PAGEOUT, and cl_page::cp_req is set to
2411 * req. cl_page_operations::cpo_make_ready() method at the particular layer
2412 * might return -EAGAIN to indicate that this page is not eligible for the
2413 * transfer right now.
2417 * Plan is to divide transfers into "priority bands" (indicated when
2418 * submitting cl_page_list, and queuing a page for the opportunistic transfer)
2419 * and allow glueing of cached pages to immediate transfers only within single
2420 * band. This would make high priority transfers (like lock cancellation or
2421 * memory pressure induced write-out) really high priority.
2426 * Per-transfer attributes.
2428 struct cl_req_attr {
2429 /** Generic attributes for the server consumption. */
2430 struct obdo *cra_oa;
2432 struct obd_capa *cra_capa;
2434 char cra_jobid[JOBSTATS_JOBID_SIZE];
2438 * Transfer request operations definable at every layer.
2440 * Concurrency: transfer formation engine synchronizes calls to all transfer
2443 struct cl_req_operations {
2445 * Invoked top-to-bottom by cl_req_prep() when transfer formation is
2446 * complete (all pages are added).
2448 * \see osc_req_prep()
2450 int (*cro_prep)(const struct lu_env *env,
2451 const struct cl_req_slice *slice);
2453 * Called top-to-bottom to fill in \a oa fields. This is called twice
2454 * with different flags, see bug 10150 and osc_build_req().
2456 * \param obj an object from cl_req which attributes are to be set in
2459 * \param oa struct obdo where attributes are placed
2461 * \param flags \a oa fields to be filled.
2463 void (*cro_attr_set)(const struct lu_env *env,
2464 const struct cl_req_slice *slice,
2465 const struct cl_object *obj,
2466 struct cl_req_attr *attr, obd_valid flags);
2468 * Called top-to-bottom from cl_req_completion() to notify layers that
2469 * transfer completed. Has to free all state allocated by
2470 * cl_device_operations::cdo_req_init().
2472 void (*cro_completion)(const struct lu_env *env,
2473 const struct cl_req_slice *slice, int ioret);
2477 * A per-object state that (potentially multi-object) transfer request keeps.
2480 /** object itself */
2481 struct cl_object *ro_obj;
2482 /** reference to cl_req_obj::ro_obj. For debugging. */
2483 struct lu_ref_link ro_obj_ref;
2484 /* something else? Number of pages for a given object? */
2490 * Transfer requests are not reference counted, because IO sub-system owns
2491 * them exclusively and knows when to free them.
2495 * cl_req is created by cl_req_alloc() that calls
2496 * cl_device_operations::cdo_req_init() device methods to allocate per-req
2497 * state in every layer.
2499 * Then pages are added (cl_req_page_add()), req keeps track of all objects it
2500 * contains pages for.
2502 * Once all pages were collected, cl_page_operations::cpo_prep() method is
2503 * called top-to-bottom. At that point layers can modify req, let it pass, or
2504 * deny it completely. This is to support things like SNS that have transfer
2505 * ordering requirements invisible to the individual req-formation engine.
2507 * On transfer completion (or transfer timeout, or failure to initiate the
2508 * transfer of an allocated req), cl_req_operations::cro_completion() method
2509 * is called, after execution of cl_page_operations::cpo_completion() of all
2513 enum cl_req_type crq_type;
2514 /** A list of pages being transfered */
2515 cfs_list_t crq_pages;
2516 /** Number of pages in cl_req::crq_pages */
2517 unsigned crq_nrpages;
2518 /** An array of objects which pages are in ->crq_pages */
2519 struct cl_req_obj *crq_o;
2520 /** Number of elements in cl_req::crq_objs[] */
2521 unsigned crq_nrobjs;
2522 cfs_list_t crq_layers;
2526 * Per-layer state for request.
2528 struct cl_req_slice {
2529 struct cl_req *crs_req;
2530 struct cl_device *crs_dev;
2531 cfs_list_t crs_linkage;
2532 const struct cl_req_operations *crs_ops;
2537 enum cache_stats_item {
2538 /** how many cache lookups were performed */
2540 /** how many times cache lookup resulted in a hit */
2542 /** how many entities are in the cache right now */
2544 /** how many entities in the cache are actively used (and cannot be
2545 * evicted) right now */
2547 /** how many entities were created at all */
2552 #define CS_NAMES { "lookup", "hit", "total", "busy", "create" }
2555 * Stats for a generic cache (similar to inode, lu_object, etc. caches).
2557 struct cache_stats {
2558 const char *cs_name;
2559 cfs_atomic_t cs_stats[CS_NR];
2562 /** These are not exported so far */
2563 void cache_stats_init (struct cache_stats *cs, const char *name);
2564 int cache_stats_print(const struct cache_stats *cs,
2565 char *page, int count, int header);
2568 * Client-side site. This represents particular client stack. "Global"
2569 * variables should (directly or indirectly) be added here to allow multiple
2570 * clients to co-exist in the single address space.
2573 struct lu_site cs_lu;
2575 * Statistical counters. Atomics do not scale, something better like
2576 * per-cpu counters is needed.
2578 * These are exported as /proc/fs/lustre/llite/.../site
2580 * When interpreting keep in mind that both sub-locks (and sub-pages)
2581 * and top-locks (and top-pages) are accounted here.
2583 struct cache_stats cs_pages;
2584 struct cache_stats cs_locks;
2585 cfs_atomic_t cs_pages_state[CPS_NR];
2586 cfs_atomic_t cs_locks_state[CLS_NR];
2589 int cl_site_init (struct cl_site *s, struct cl_device *top);
2590 void cl_site_fini (struct cl_site *s);
2591 void cl_stack_fini(const struct lu_env *env, struct cl_device *cl);
2594 * Output client site statistical counters into a buffer. Suitable for
2595 * ll_rd_*()-style functions.
2597 int cl_site_stats_print(const struct cl_site *s, char *page, int count);
2602 * Type conversion and accessory functions.
2606 static inline struct cl_site *lu2cl_site(const struct lu_site *site)
2608 return container_of(site, struct cl_site, cs_lu);
2611 static inline int lu_device_is_cl(const struct lu_device *d)
2613 return d->ld_type->ldt_tags & LU_DEVICE_CL;
2616 static inline struct cl_device *lu2cl_dev(const struct lu_device *d)
2618 LASSERT(d == NULL || IS_ERR(d) || lu_device_is_cl(d));
2619 return container_of0(d, struct cl_device, cd_lu_dev);
2622 static inline struct lu_device *cl2lu_dev(struct cl_device *d)
2624 return &d->cd_lu_dev;
2627 static inline struct cl_object *lu2cl(const struct lu_object *o)
2629 LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->lo_dev));
2630 return container_of0(o, struct cl_object, co_lu);
2633 static inline const struct cl_object_conf *
2634 lu2cl_conf(const struct lu_object_conf *conf)
2636 return container_of0(conf, struct cl_object_conf, coc_lu);
2639 static inline struct cl_object *cl_object_next(const struct cl_object *obj)
2641 return obj ? lu2cl(lu_object_next(&obj->co_lu)) : NULL;
2644 static inline struct cl_device *cl_object_device(const struct cl_object *o)
2646 LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->co_lu.lo_dev));
2647 return container_of0(o->co_lu.lo_dev, struct cl_device, cd_lu_dev);
2650 static inline struct cl_object_header *luh2coh(const struct lu_object_header *h)
2652 return container_of0(h, struct cl_object_header, coh_lu);
2655 static inline struct cl_site *cl_object_site(const struct cl_object *obj)
2657 return lu2cl_site(obj->co_lu.lo_dev->ld_site);
2661 struct cl_object_header *cl_object_header(const struct cl_object *obj)
2663 return luh2coh(obj->co_lu.lo_header);
2666 static inline int cl_device_init(struct cl_device *d, struct lu_device_type *t)
2668 return lu_device_init(&d->cd_lu_dev, t);
2671 static inline void cl_device_fini(struct cl_device *d)
2673 lu_device_fini(&d->cd_lu_dev);
2676 void cl_page_slice_add(struct cl_page *page, struct cl_page_slice *slice,
2677 struct cl_object *obj,
2678 const struct cl_page_operations *ops);
2679 void cl_lock_slice_add(struct cl_lock *lock, struct cl_lock_slice *slice,
2680 struct cl_object *obj,
2681 const struct cl_lock_operations *ops);
2682 void cl_io_slice_add(struct cl_io *io, struct cl_io_slice *slice,
2683 struct cl_object *obj, const struct cl_io_operations *ops);
2684 void cl_req_slice_add(struct cl_req *req, struct cl_req_slice *slice,
2685 struct cl_device *dev,
2686 const struct cl_req_operations *ops);
2689 /** \defgroup cl_object cl_object
2691 struct cl_object *cl_object_top (struct cl_object *o);
2692 struct cl_object *cl_object_find(const struct lu_env *env, struct cl_device *cd,
2693 const struct lu_fid *fid,
2694 const struct cl_object_conf *c);
2696 int cl_object_header_init(struct cl_object_header *h);
2697 void cl_object_header_fini(struct cl_object_header *h);
2698 void cl_object_put (const struct lu_env *env, struct cl_object *o);
2699 void cl_object_get (struct cl_object *o);
2700 void cl_object_attr_lock (struct cl_object *o);
2701 void cl_object_attr_unlock(struct cl_object *o);
2702 int cl_object_attr_get (const struct lu_env *env, struct cl_object *obj,
2703 struct cl_attr *attr);
2704 int cl_object_attr_set (const struct lu_env *env, struct cl_object *obj,
2705 const struct cl_attr *attr, unsigned valid);
2706 int cl_object_glimpse (const struct lu_env *env, struct cl_object *obj,
2707 struct ost_lvb *lvb);
2708 int cl_conf_set (const struct lu_env *env, struct cl_object *obj,
2709 const struct cl_object_conf *conf);
2710 void cl_object_prune (const struct lu_env *env, struct cl_object *obj);
2711 void cl_object_kill (const struct lu_env *env, struct cl_object *obj);
2712 int cl_object_has_locks (struct cl_object *obj);
2715 * Returns true, iff \a o0 and \a o1 are slices of the same object.
2717 static inline int cl_object_same(struct cl_object *o0, struct cl_object *o1)
2719 return cl_object_header(o0) == cl_object_header(o1);
2722 static inline void cl_object_page_init(struct cl_object *clob, int size)
2724 clob->co_slice_off = cl_object_header(clob)->coh_page_bufsize;
2725 cl_object_header(clob)->coh_page_bufsize += ALIGN(size, 8);
2728 static inline void *cl_object_page_slice(struct cl_object *clob,
2729 struct cl_page *page)
2731 return (void *)((char *)page + clob->co_slice_off);
2735 * Return refcount of cl_object.
2737 static inline int cl_object_refc(struct cl_object *clob)
2739 struct lu_object_header *header = clob->co_lu.lo_header;
2740 return cfs_atomic_read(&header->loh_ref);
2745 /** \defgroup cl_page cl_page
2753 /* callback of cl_page_gang_lookup() */
2755 struct cl_page *cl_page_find (const struct lu_env *env,
2756 struct cl_object *obj,
2757 pgoff_t idx, struct page *vmpage,
2758 enum cl_page_type type);
2759 struct cl_page *cl_page_alloc (const struct lu_env *env,
2760 struct cl_object *o, pgoff_t ind,
2761 struct page *vmpage,
2762 enum cl_page_type type);
2763 void cl_page_get (struct cl_page *page);
2764 void cl_page_put (const struct lu_env *env,
2765 struct cl_page *page);
2766 void cl_page_print (const struct lu_env *env, void *cookie,
2767 lu_printer_t printer,
2768 const struct cl_page *pg);
2769 void cl_page_header_print(const struct lu_env *env, void *cookie,
2770 lu_printer_t printer,
2771 const struct cl_page *pg);
2772 struct page *cl_page_vmpage (const struct lu_env *env,
2773 struct cl_page *page);
2774 struct cl_page *cl_vmpage_page (struct page *vmpage, struct cl_object *obj);
2775 struct cl_page *cl_page_top (struct cl_page *page);
2777 const struct cl_page_slice *cl_page_at(const struct cl_page *page,
2778 const struct lu_device_type *dtype);
2783 * Functions dealing with the ownership of page by io.
2787 int cl_page_own (const struct lu_env *env,
2788 struct cl_io *io, struct cl_page *page);
2789 int cl_page_own_try (const struct lu_env *env,
2790 struct cl_io *io, struct cl_page *page);
2791 void cl_page_assume (const struct lu_env *env,
2792 struct cl_io *io, struct cl_page *page);
2793 void cl_page_unassume (const struct lu_env *env,
2794 struct cl_io *io, struct cl_page *pg);
2795 void cl_page_disown (const struct lu_env *env,
2796 struct cl_io *io, struct cl_page *page);
2797 int cl_page_is_owned (const struct cl_page *pg, const struct cl_io *io);
2804 * Functions dealing with the preparation of a page for a transfer, and
2805 * tracking transfer state.
2808 int cl_page_prep (const struct lu_env *env, struct cl_io *io,
2809 struct cl_page *pg, enum cl_req_type crt);
2810 void cl_page_completion (const struct lu_env *env,
2811 struct cl_page *pg, enum cl_req_type crt, int ioret);
2812 int cl_page_make_ready (const struct lu_env *env, struct cl_page *pg,
2813 enum cl_req_type crt);
2814 int cl_page_cache_add (const struct lu_env *env, struct cl_io *io,
2815 struct cl_page *pg, enum cl_req_type crt);
2816 void cl_page_clip (const struct lu_env *env, struct cl_page *pg,
2818 int cl_page_cancel (const struct lu_env *env, struct cl_page *page);
2819 int cl_page_flush (const struct lu_env *env, struct cl_io *io,
2820 struct cl_page *pg);
2826 * \name helper routines
2827 * Functions to discard, delete and export a cl_page.
2830 void cl_page_discard (const struct lu_env *env, struct cl_io *io,
2831 struct cl_page *pg);
2832 void cl_page_delete (const struct lu_env *env, struct cl_page *pg);
2833 int cl_page_is_vmlocked (const struct lu_env *env,
2834 const struct cl_page *pg);
2835 void cl_page_export (const struct lu_env *env,
2836 struct cl_page *pg, int uptodate);
2837 int cl_page_is_under_lock(const struct lu_env *env, struct cl_io *io,
2838 struct cl_page *page);
2839 loff_t cl_offset (const struct cl_object *obj, pgoff_t idx);
2840 pgoff_t cl_index (const struct cl_object *obj, loff_t offset);
2841 int cl_page_size (const struct cl_object *obj);
2842 int cl_pages_prune (const struct lu_env *env, struct cl_object *obj);
2844 void cl_lock_print (const struct lu_env *env, void *cookie,
2845 lu_printer_t printer, const struct cl_lock *lock);
2846 void cl_lock_descr_print(const struct lu_env *env, void *cookie,
2847 lu_printer_t printer,
2848 const struct cl_lock_descr *descr);
2853 /** \defgroup cl_lock cl_lock
2856 struct cl_lock *cl_lock_hold(const struct lu_env *env, const struct cl_io *io,
2857 const struct cl_lock_descr *need,
2858 const char *scope, const void *source);
2859 struct cl_lock *cl_lock_peek(const struct lu_env *env, const struct cl_io *io,
2860 const struct cl_lock_descr *need,
2861 const char *scope, const void *source);
2862 struct cl_lock *cl_lock_request(const struct lu_env *env, struct cl_io *io,
2863 const struct cl_lock_descr *need,
2864 const char *scope, const void *source);
2865 struct cl_lock *cl_lock_at_pgoff(const struct lu_env *env,
2866 struct cl_object *obj, pgoff_t index,
2867 struct cl_lock *except, int pending,
2869 static inline struct cl_lock *cl_lock_at_page(const struct lu_env *env,
2870 struct cl_object *obj,
2871 struct cl_page *page,
2872 struct cl_lock *except,
2873 int pending, int canceld)
2875 LASSERT(cl_object_header(obj) == cl_object_header(page->cp_obj));
2876 return cl_lock_at_pgoff(env, obj, page->cp_index, except,
2880 const struct cl_lock_slice *cl_lock_at(const struct cl_lock *lock,
2881 const struct lu_device_type *dtype);
2883 void cl_lock_get (struct cl_lock *lock);
2884 void cl_lock_get_trust (struct cl_lock *lock);
2885 void cl_lock_put (const struct lu_env *env, struct cl_lock *lock);
2886 void cl_lock_hold_add (const struct lu_env *env, struct cl_lock *lock,
2887 const char *scope, const void *source);
2888 void cl_lock_hold_release(const struct lu_env *env, struct cl_lock *lock,
2889 const char *scope, const void *source);
2890 void cl_lock_unhold (const struct lu_env *env, struct cl_lock *lock,
2891 const char *scope, const void *source);
2892 void cl_lock_release (const struct lu_env *env, struct cl_lock *lock,
2893 const char *scope, const void *source);
2894 void cl_lock_user_add (const struct lu_env *env, struct cl_lock *lock);
2895 void cl_lock_user_del (const struct lu_env *env, struct cl_lock *lock);
2897 enum cl_lock_state cl_lock_intransit(const struct lu_env *env,
2898 struct cl_lock *lock);
2899 void cl_lock_extransit(const struct lu_env *env, struct cl_lock *lock,
2900 enum cl_lock_state state);
2901 int cl_lock_is_intransit(struct cl_lock *lock);
2903 int cl_lock_enqueue_wait(const struct lu_env *env, struct cl_lock *lock,
2906 /** \name statemachine statemachine
2907 * Interface to lock state machine consists of 3 parts:
2909 * - "try" functions that attempt to effect a state transition. If state
2910 * transition is not possible right now (e.g., if it has to wait for some
2911 * asynchronous event to occur), these functions return
2912 * cl_lock_transition::CLO_WAIT.
2914 * - "non-try" functions that implement synchronous blocking interface on
2915 * top of non-blocking "try" functions. These functions repeatedly call
2916 * corresponding "try" versions, and if state transition is not possible
2917 * immediately, wait for lock state change.
2919 * - methods from cl_lock_operations, called by "try" functions. Lock can
2920 * be advanced to the target state only when all layers voted that they
2921 * are ready for this transition. "Try" functions call methods under lock
2922 * mutex. If a layer had to release a mutex, it re-acquires it and returns
2923 * cl_lock_transition::CLO_REPEAT, causing "try" function to call all
2926 * TRY NON-TRY METHOD FINAL STATE
2928 * cl_enqueue_try() cl_enqueue() cl_lock_operations::clo_enqueue() CLS_ENQUEUED
2930 * cl_wait_try() cl_wait() cl_lock_operations::clo_wait() CLS_HELD
2932 * cl_unuse_try() cl_unuse() cl_lock_operations::clo_unuse() CLS_CACHED
2934 * cl_use_try() NONE cl_lock_operations::clo_use() CLS_HELD
2938 int cl_enqueue (const struct lu_env *env, struct cl_lock *lock,
2939 struct cl_io *io, __u32 flags);
2940 int cl_wait (const struct lu_env *env, struct cl_lock *lock);
2941 void cl_unuse (const struct lu_env *env, struct cl_lock *lock);
2942 int cl_enqueue_try(const struct lu_env *env, struct cl_lock *lock,
2943 struct cl_io *io, __u32 flags);
2944 int cl_unuse_try (const struct lu_env *env, struct cl_lock *lock);
2945 int cl_wait_try (const struct lu_env *env, struct cl_lock *lock);
2946 int cl_use_try (const struct lu_env *env, struct cl_lock *lock, int atomic);
2948 /** @} statemachine */
2950 void cl_lock_signal (const struct lu_env *env, struct cl_lock *lock);
2951 int cl_lock_state_wait (const struct lu_env *env, struct cl_lock *lock);
2952 void cl_lock_state_set (const struct lu_env *env, struct cl_lock *lock,
2953 enum cl_lock_state state);
2954 int cl_queue_match (const cfs_list_t *queue,
2955 const struct cl_lock_descr *need);
2957 void cl_lock_mutex_get (const struct lu_env *env, struct cl_lock *lock);
2958 int cl_lock_mutex_try (const struct lu_env *env, struct cl_lock *lock);
2959 void cl_lock_mutex_put (const struct lu_env *env, struct cl_lock *lock);
2960 int cl_lock_is_mutexed (struct cl_lock *lock);
2961 int cl_lock_nr_mutexed (const struct lu_env *env);
2962 int cl_lock_discard_pages(const struct lu_env *env, struct cl_lock *lock);
2963 int cl_lock_ext_match (const struct cl_lock_descr *has,
2964 const struct cl_lock_descr *need);
2965 int cl_lock_descr_match(const struct cl_lock_descr *has,
2966 const struct cl_lock_descr *need);
2967 int cl_lock_mode_match (enum cl_lock_mode has, enum cl_lock_mode need);
2968 int cl_lock_modify (const struct lu_env *env, struct cl_lock *lock,
2969 const struct cl_lock_descr *desc);
2971 void cl_lock_closure_init (const struct lu_env *env,
2972 struct cl_lock_closure *closure,
2973 struct cl_lock *origin, int wait);
2974 void cl_lock_closure_fini (struct cl_lock_closure *closure);
2975 int cl_lock_closure_build(const struct lu_env *env, struct cl_lock *lock,
2976 struct cl_lock_closure *closure);
2977 void cl_lock_disclosure (const struct lu_env *env,
2978 struct cl_lock_closure *closure);
2979 int cl_lock_enclosure (const struct lu_env *env, struct cl_lock *lock,
2980 struct cl_lock_closure *closure);
2982 void cl_lock_cancel(const struct lu_env *env, struct cl_lock *lock);
2983 void cl_lock_delete(const struct lu_env *env, struct cl_lock *lock);
2984 void cl_lock_error (const struct lu_env *env, struct cl_lock *lock, int error);
2985 void cl_locks_prune(const struct lu_env *env, struct cl_object *obj, int wait);
2987 unsigned long cl_lock_weigh(const struct lu_env *env, struct cl_lock *lock);
2991 /** \defgroup cl_io cl_io
2994 int cl_io_init (const struct lu_env *env, struct cl_io *io,
2995 enum cl_io_type iot, struct cl_object *obj);
2996 int cl_io_sub_init (const struct lu_env *env, struct cl_io *io,
2997 enum cl_io_type iot, struct cl_object *obj);
2998 int cl_io_rw_init (const struct lu_env *env, struct cl_io *io,
2999 enum cl_io_type iot, loff_t pos, size_t count);
3000 int cl_io_loop (const struct lu_env *env, struct cl_io *io);
3002 void cl_io_fini (const struct lu_env *env, struct cl_io *io);
3003 int cl_io_iter_init (const struct lu_env *env, struct cl_io *io);
3004 void cl_io_iter_fini (const struct lu_env *env, struct cl_io *io);
3005 int cl_io_lock (const struct lu_env *env, struct cl_io *io);
3006 void cl_io_unlock (const struct lu_env *env, struct cl_io *io);
3007 int cl_io_start (const struct lu_env *env, struct cl_io *io);
3008 void cl_io_end (const struct lu_env *env, struct cl_io *io);
3009 int cl_io_lock_add (const struct lu_env *env, struct cl_io *io,
3010 struct cl_io_lock_link *link);
3011 int cl_io_lock_alloc_add(const struct lu_env *env, struct cl_io *io,
3012 struct cl_lock_descr *descr);
3013 int cl_io_read_page (const struct lu_env *env, struct cl_io *io,
3014 struct cl_page *page);
3015 int cl_io_submit_rw (const struct lu_env *env, struct cl_io *io,
3016 enum cl_req_type iot, struct cl_2queue *queue);
3017 int cl_io_submit_sync (const struct lu_env *env, struct cl_io *io,
3018 enum cl_req_type iot, struct cl_2queue *queue,
3020 int cl_io_commit_async (const struct lu_env *env, struct cl_io *io,
3021 struct cl_page_list *queue, int from, int to,
3023 void cl_io_rw_advance (const struct lu_env *env, struct cl_io *io,
3025 int cl_io_cancel (const struct lu_env *env, struct cl_io *io,
3026 struct cl_page_list *queue);
3027 int cl_io_is_going (const struct lu_env *env);
3030 * True, iff \a io is an O_APPEND write(2).
3032 static inline int cl_io_is_append(const struct cl_io *io)
3034 return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_append;
3037 static inline int cl_io_is_sync_write(const struct cl_io *io)
3039 return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_sync;
3042 static inline int cl_io_is_mkwrite(const struct cl_io *io)
3044 return io->ci_type == CIT_FAULT && io->u.ci_fault.ft_mkwrite;
3048 * True, iff \a io is a truncate(2).
3050 static inline int cl_io_is_trunc(const struct cl_io *io)
3052 return io->ci_type == CIT_SETATTR &&
3053 (io->u.ci_setattr.sa_valid & ATTR_SIZE);
3056 struct cl_io *cl_io_top(struct cl_io *io);
3058 void cl_io_print(const struct lu_env *env, void *cookie,
3059 lu_printer_t printer, const struct cl_io *io);
3061 #define CL_IO_SLICE_CLEAN(foo_io, base) \
3063 typeof(foo_io) __foo_io = (foo_io); \
3065 CLASSERT(offsetof(typeof(*__foo_io), base) == 0); \
3066 memset(&__foo_io->base + 1, 0, \
3067 (sizeof *__foo_io) - sizeof __foo_io->base); \
3072 /** \defgroup cl_page_list cl_page_list
3076 * Last page in the page list.
3078 static inline struct cl_page *cl_page_list_last(struct cl_page_list *plist)
3080 LASSERT(plist->pl_nr > 0);
3081 return cfs_list_entry(plist->pl_pages.prev, struct cl_page, cp_batch);
3084 static inline struct cl_page *cl_page_list_first(struct cl_page_list *plist)
3086 LASSERT(plist->pl_nr > 0);
3087 return cfs_list_entry(plist->pl_pages.next, struct cl_page, cp_batch);
3091 * Iterate over pages in a page list.
3093 #define cl_page_list_for_each(page, list) \
3094 cfs_list_for_each_entry((page), &(list)->pl_pages, cp_batch)
3097 * Iterate over pages in a page list, taking possible removals into account.
3099 #define cl_page_list_for_each_safe(page, temp, list) \
3100 cfs_list_for_each_entry_safe((page), (temp), &(list)->pl_pages, cp_batch)
3102 void cl_page_list_init (struct cl_page_list *plist);
3103 void cl_page_list_add (struct cl_page_list *plist, struct cl_page *page);
3104 void cl_page_list_move (struct cl_page_list *dst, struct cl_page_list *src,
3105 struct cl_page *page);
3106 void cl_page_list_move_head(struct cl_page_list *dst, struct cl_page_list *src,
3107 struct cl_page *page);
3108 void cl_page_list_splice (struct cl_page_list *list,
3109 struct cl_page_list *head);
3110 void cl_page_list_del (const struct lu_env *env,
3111 struct cl_page_list *plist, struct cl_page *page);
3112 void cl_page_list_disown (const struct lu_env *env,
3113 struct cl_io *io, struct cl_page_list *plist);
3114 int cl_page_list_own (const struct lu_env *env,
3115 struct cl_io *io, struct cl_page_list *plist);
3116 void cl_page_list_assume (const struct lu_env *env,
3117 struct cl_io *io, struct cl_page_list *plist);
3118 void cl_page_list_discard(const struct lu_env *env,
3119 struct cl_io *io, struct cl_page_list *plist);
3120 void cl_page_list_fini (const struct lu_env *env, struct cl_page_list *plist);
3122 void cl_2queue_init (struct cl_2queue *queue);
3123 void cl_2queue_add (struct cl_2queue *queue, struct cl_page *page);
3124 void cl_2queue_disown (const struct lu_env *env,
3125 struct cl_io *io, struct cl_2queue *queue);
3126 void cl_2queue_assume (const struct lu_env *env,
3127 struct cl_io *io, struct cl_2queue *queue);
3128 void cl_2queue_discard (const struct lu_env *env,
3129 struct cl_io *io, struct cl_2queue *queue);
3130 void cl_2queue_fini (const struct lu_env *env, struct cl_2queue *queue);
3131 void cl_2queue_init_page(struct cl_2queue *queue, struct cl_page *page);
3133 /** @} cl_page_list */
3135 /** \defgroup cl_req cl_req
3137 struct cl_req *cl_req_alloc(const struct lu_env *env, struct cl_page *page,
3138 enum cl_req_type crt, int nr_objects);
3140 void cl_req_page_add (const struct lu_env *env, struct cl_req *req,
3141 struct cl_page *page);
3142 void cl_req_page_done (const struct lu_env *env, struct cl_page *page);
3143 int cl_req_prep (const struct lu_env *env, struct cl_req *req);
3144 void cl_req_attr_set (const struct lu_env *env, struct cl_req *req,
3145 struct cl_req_attr *attr, obd_valid flags);
3146 void cl_req_completion(const struct lu_env *env, struct cl_req *req, int ioret);
3148 /** \defgroup cl_sync_io cl_sync_io
3152 * Anchor for synchronous transfer. This is allocated on a stack by thread
3153 * doing synchronous transfer, and a pointer to this structure is set up in
3154 * every page submitted for transfer. Transfer completion routine updates
3155 * anchor and wakes up waiting thread when transfer is complete.
3158 /** number of pages yet to be transferred. */
3159 cfs_atomic_t csi_sync_nr;
3162 /** barrier of destroy this structure */
3163 cfs_atomic_t csi_barrier;
3164 /** completion to be signaled when transfer is complete. */
3165 wait_queue_head_t csi_waitq;
3168 void cl_sync_io_init(struct cl_sync_io *anchor, int nrpages);
3169 int cl_sync_io_wait(const struct lu_env *env, struct cl_io *io,
3170 struct cl_page_list *queue, struct cl_sync_io *anchor,
3172 void cl_sync_io_note(struct cl_sync_io *anchor, int ioret);
3174 /** @} cl_sync_io */
3178 /** \defgroup cl_env cl_env
3180 * lu_env handling for a client.
3182 * lu_env is an environment within which lustre code executes. Its major part
3183 * is lu_context---a fast memory allocation mechanism that is used to conserve
3184 * precious kernel stack space. Originally lu_env was designed for a server,
3187 * - there is a (mostly) fixed number of threads, and
3189 * - call chains have no non-lustre portions inserted between lustre code.
3191 * On a client both these assumtpion fails, because every user thread can
3192 * potentially execute lustre code as part of a system call, and lustre calls
3193 * into VFS or MM that call back into lustre.
3195 * To deal with that, cl_env wrapper functions implement the following
3198 * - allocation and destruction of environment is amortized by caching no
3199 * longer used environments instead of destroying them;
3201 * - there is a notion of "current" environment, attached to the kernel
3202 * data structure representing current thread Top-level lustre code
3203 * allocates an environment and makes it current, then calls into
3204 * non-lustre code, that in turn calls lustre back. Low-level lustre
3205 * code thus called can fetch environment created by the top-level code
3206 * and reuse it, avoiding additional environment allocation.
3207 * Right now, three interfaces can attach the cl_env to running thread:
3210 * - cl_env_reexit(cl_env_reenter had to be called priorly)
3212 * \see lu_env, lu_context, lu_context_key
3215 struct cl_env_nest {
3220 struct lu_env *cl_env_peek (int *refcheck);
3221 struct lu_env *cl_env_get (int *refcheck);
3222 struct lu_env *cl_env_alloc (int *refcheck, __u32 tags);
3223 struct lu_env *cl_env_nested_get (struct cl_env_nest *nest);
3224 void cl_env_put (struct lu_env *env, int *refcheck);
3225 void cl_env_nested_put (struct cl_env_nest *nest, struct lu_env *env);
3226 void *cl_env_reenter (void);
3227 void cl_env_reexit (void *cookie);
3228 void cl_env_implant (struct lu_env *env, int *refcheck);
3229 void cl_env_unplant (struct lu_env *env, int *refcheck);
3230 unsigned cl_env_cache_purge(unsigned nr);
3231 struct lu_env *cl_env_percpu_get (void);
3232 void cl_env_percpu_put (struct lu_env *env);
3239 void cl_attr2lvb(struct ost_lvb *lvb, const struct cl_attr *attr);
3240 void cl_lvb2attr(struct cl_attr *attr, const struct ost_lvb *lvb);
3242 struct cl_device *cl_type_setup(const struct lu_env *env, struct lu_site *site,
3243 struct lu_device_type *ldt,
3244 struct lu_device *next);
3247 int cl_global_init(void);
3248 void cl_global_fini(void);
3250 #endif /* _LINUX_CL_OBJECT_H */