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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>
103 # include <linux/mutex.h>
104 # include <linux/radix-tree.h>
110 struct cl_device_operations;
113 struct cl_object_page_operations;
114 struct cl_object_lock_operations;
117 struct cl_page_slice;
119 struct cl_lock_slice;
121 struct cl_lock_operations;
122 struct cl_page_operations;
131 * Operations for each data device in the client stack.
133 * \see vvp_cl_ops, lov_cl_ops, lovsub_cl_ops, osc_cl_ops
135 struct cl_device_operations {
137 * Initialize cl_req. This method is called top-to-bottom on all
138 * devices in the stack to get them a chance to allocate layer-private
139 * data, and to attach them to the cl_req by calling
140 * cl_req_slice_add().
142 * \see osc_req_init(), lov_req_init(), lovsub_req_init()
143 * \see ccc_req_init()
145 int (*cdo_req_init)(const struct lu_env *env, struct cl_device *dev,
150 * Device in the client stack.
152 * \see ccc_device, lov_device, lovsub_device, osc_device
156 struct lu_device cd_lu_dev;
157 /** Per-layer operation vector. */
158 const struct cl_device_operations *cd_ops;
161 /** \addtogroup cl_object cl_object
164 * "Data attributes" of cl_object. Data attributes can be updated
165 * independently for a sub-object, and top-object's attributes are calculated
166 * from sub-objects' ones.
169 /** Object size, in bytes */
172 * Known minimal size, in bytes.
174 * This is only valid when at least one DLM lock is held.
177 /** Modification time. Measured in seconds since epoch. */
179 /** Access time. Measured in seconds since epoch. */
181 /** Change time. Measured in seconds since epoch. */
184 * Blocks allocated to this cl_object on the server file system.
186 * \todo XXX An interface for block size is needed.
190 * User identifier for quota purposes.
194 * Group identifier for quota purposes.
200 * Fields in cl_attr that are being set.
214 * Sub-class of lu_object with methods common for objects on the client
217 * cl_object: represents a regular file system object, both a file and a
218 * stripe. cl_object is based on lu_object: it is identified by a fid,
219 * layered, cached, hashed, and lrued. Important distinction with the server
220 * side, where md_object and dt_object are used, is that cl_object "fans out"
221 * at the lov/sns level: depending on the file layout, single file is
222 * represented as a set of "sub-objects" (stripes). At the implementation
223 * level, struct lov_object contains an array of cl_objects. Each sub-object
224 * is a full-fledged cl_object, having its fid, living in the lru and hash
227 * This leads to the next important difference with the server side: on the
228 * client, it's quite usual to have objects with the different sequence of
229 * layers. For example, typical top-object is composed of the following
235 * whereas its sub-objects are composed of
240 * layers. Here "lovsub" is a mostly dummy layer, whose purpose is to keep
241 * track of the object-subobject relationship.
243 * Sub-objects are not cached independently: when top-object is about to
244 * be discarded from the memory, all its sub-objects are torn-down and
247 * \see ccc_object, lov_object, lovsub_object, osc_object
251 struct lu_object co_lu;
252 /** per-object-layer operations */
253 const struct cl_object_operations *co_ops;
257 * Description of the client object configuration. This is used for the
258 * creation of a new client object that is identified by a more state than
261 struct cl_object_conf {
263 struct lu_object_conf coc_lu;
266 * Object layout. This is consumed by lov.
268 struct lustre_md *coc_md;
270 * Description of particular stripe location in the
271 * cluster. This is consumed by osc.
273 struct lov_oinfo *coc_oinfo;
276 * VFS inode. This is consumed by vvp.
278 struct inode *coc_inode;
282 * Operations implemented for each cl object layer.
284 * \see vvp_ops, lov_ops, lovsub_ops, osc_ops
286 struct cl_object_operations {
288 * Initialize page slice for this layer. Called top-to-bottom through
289 * every object layer when a new cl_page is instantiated. Layer
290 * keeping private per-page data, or requiring its own page operations
291 * vector should allocate these data here, and attach then to the page
292 * by calling cl_page_slice_add(). \a vmpage is locked (in the VM
295 * \retval NULL success.
297 * \retval ERR_PTR(errno) failure code.
299 * \retval valid-pointer pointer to already existing referenced page
300 * to be used instead of newly created.
302 struct cl_page *(*coo_page_init)(const struct lu_env *env,
303 struct cl_object *obj,
304 struct cl_page *page,
307 * Initialize lock slice for this layer. Called top-to-bottom through
308 * every object layer when a new cl_lock is instantiated. Layer
309 * keeping private per-lock data, or requiring its own lock operations
310 * vector should allocate these data here, and attach then to the lock
311 * by calling cl_lock_slice_add(). Mandatory.
313 int (*coo_lock_init)(const struct lu_env *env,
314 struct cl_object *obj, struct cl_lock *lock,
315 const struct cl_io *io);
317 * Initialize io state for a given layer.
319 * called top-to-bottom once per io existence to initialize io
320 * state. If layer wants to keep some state for this type of io, it
321 * has to embed struct cl_io_slice in lu_env::le_ses, and register
322 * slice with cl_io_slice_add(). It is guaranteed that all threads
323 * participating in this io share the same session.
325 int (*coo_io_init)(const struct lu_env *env,
326 struct cl_object *obj, struct cl_io *io);
328 * Fill portion of \a attr that this layer controls. This method is
329 * called top-to-bottom through all object layers.
331 * \pre cl_object_header::coh_attr_guard of the top-object is locked.
333 * \return 0: to continue
334 * \return +ve: to stop iterating through layers (but 0 is returned
335 * from enclosing cl_object_attr_get())
336 * \return -ve: to signal error
338 int (*coo_attr_get)(const struct lu_env *env, struct cl_object *obj,
339 struct cl_attr *attr);
343 * \a valid is a bitmask composed from enum #cl_attr_valid, and
344 * indicating what attributes are to be set.
346 * \pre cl_object_header::coh_attr_guard of the top-object is locked.
348 * \return the same convention as for
349 * cl_object_operations::coo_attr_get() is used.
351 int (*coo_attr_set)(const struct lu_env *env, struct cl_object *obj,
352 const struct cl_attr *attr, unsigned valid);
354 * Update object configuration. Called top-to-bottom to modify object
357 * XXX error conditions and handling.
359 int (*coo_conf_set)(const struct lu_env *env, struct cl_object *obj,
360 const struct cl_object_conf *conf);
362 * Glimpse ast. Executed when glimpse ast arrives for a lock on this
363 * object. Layers are supposed to fill parts of \a lvb that will be
364 * shipped to the glimpse originator as a glimpse result.
366 * \see ccc_object_glimpse(), lovsub_object_glimpse(),
367 * \see osc_object_glimpse()
369 int (*coo_glimpse)(const struct lu_env *env,
370 const struct cl_object *obj, struct ost_lvb *lvb);
374 * Extended header for client object.
376 struct cl_object_header {
377 /** Standard lu_object_header. cl_object::co_lu::lo_header points
379 struct lu_object_header coh_lu;
381 * \todo XXX move locks below to the separate cache-lines, they are
382 * mostly useless otherwise.
385 /** Lock protecting page tree. */
386 spinlock_t coh_page_guard;
387 /** Lock protecting lock list. */
388 spinlock_t coh_lock_guard;
390 /** Radix tree of cl_page's, cached for this object. */
391 struct radix_tree_root coh_tree;
392 /** # of pages in radix tree. */
393 unsigned long coh_pages;
394 /** List of cl_lock's granted for this object. */
395 struct list_head coh_locks;
398 * Parent object. It is assumed that an object has a well-defined
399 * parent, but not a well-defined child (there may be multiple
400 * sub-objects, for the same top-object). cl_object_header::coh_parent
401 * field allows certain code to be written generically, without
402 * limiting possible cl_object layouts unduly.
404 struct cl_object_header *coh_parent;
406 * Protects consistency between cl_attr of parent object and
407 * attributes of sub-objects, that the former is calculated ("merged")
410 * \todo XXX this can be read/write lock if needed.
412 spinlock_t coh_attr_guard;
414 * Number of objects above this one: 0 for a top-object, 1 for its
417 unsigned coh_nesting;
421 * Helper macro: iterate over all layers of the object \a obj, assigning every
422 * layer top-to-bottom to \a slice.
424 #define cl_object_for_each(slice, obj) \
425 list_for_each_entry((slice), \
426 &(obj)->co_lu.lo_header->loh_layers, \
429 * Helper macro: iterate over all layers of the object \a obj, assigning every
430 * layer bottom-to-top to \a slice.
432 #define cl_object_for_each_reverse(slice, obj) \
433 list_for_each_entry_reverse((slice), \
434 &(obj)->co_lu.lo_header->loh_layers, \
439 #define pgoff_t unsigned long
442 #define CL_PAGE_EOF ((pgoff_t)~0ull)
444 /** \addtogroup cl_page cl_page
448 * Layered client page.
450 * cl_page: represents a portion of a file, cached in the memory. All pages
451 * of the given file are of the same size, and are kept in the radix tree
452 * hanging off the cl_object. cl_page doesn't fan out, but as sub-objects
453 * of the top-level file object are first class cl_objects, they have their
454 * own radix trees of pages and hence page is implemented as a sequence of
455 * struct cl_pages's, linked into double-linked list through
456 * cl_page::cp_parent and cl_page::cp_child pointers, each residing in the
457 * corresponding radix tree at the corresponding logical offset.
459 * cl_page is associated with VM page of the hosting environment (struct
460 * page in Linux kernel, for example), cfs_page_t. It is assumed, that this
461 * association is implemented by one of cl_page layers (top layer in the
462 * current design) that
464 * - intercepts per-VM-page call-backs made by the environment (e.g.,
467 * - translates state (page flag bits) and locking between lustre and
470 * The association between cl_page and cfs_page_t is immutable and
471 * established when cl_page is created.
473 * cl_page can be "owned" by a particular cl_io (see below), guaranteeing
474 * this io an exclusive access to this page w.r.t. other io attempts and
475 * various events changing page state (such as transfer completion, or
476 * eviction of the page from the memory). Note, that in general cl_io
477 * cannot be identified with a particular thread, and page ownership is not
478 * exactly equal to the current thread holding a lock on the page. Layer
479 * implementing association between cl_page and cfs_page_t has to implement
480 * ownership on top of available synchronization mechanisms.
482 * While lustre client maintains the notion of an page ownership by io,
483 * hosting MM/VM usually has its own page concurrency control
484 * mechanisms. For example, in Linux, page access is synchronized by the
485 * per-page PG_locked bit-lock, and generic kernel code (generic_file_*())
486 * takes care to acquire and release such locks as necessary around the
487 * calls to the file system methods (->readpage(), ->prepare_write(),
488 * ->commit_write(), etc.). This leads to the situation when there are two
489 * different ways to own a page in the client:
491 * - client code explicitly and voluntary owns the page (cl_page_own());
493 * - VM locks a page and then calls the client, that has "to assume"
494 * the ownership from the VM (cl_page_assume()).
496 * Dual methods to release ownership are cl_page_disown() and
497 * cl_page_unassume().
499 * cl_page is reference counted (cl_page::cp_ref). When reference counter
500 * drops to 0, the page is returned to the cache, unless it is in
501 * cl_page_state::CPS_FREEING state, in which case it is immediately
504 * The general logic guaranteeing the absence of "existential races" for
505 * pages is the following:
507 * - there are fixed known ways for a thread to obtain a new reference
510 * - by doing a lookup in the cl_object radix tree, protected by the
513 * - by starting from VM-locked cfs_page_t and following some
514 * hosting environment method (e.g., following ->private pointer in
515 * the case of Linux kernel), see cl_vmpage_page();
517 * - when the page enters cl_page_state::CPS_FREEING state, all these
518 * ways are severed with the proper synchronization
519 * (cl_page_delete());
521 * - entry into cl_page_state::CPS_FREEING is serialized by the VM page
524 * - no new references to the page in cl_page_state::CPS_FREEING state
525 * are allowed (checked in cl_page_get()).
527 * Together this guarantees that when last reference to a
528 * cl_page_state::CPS_FREEING page is released, it is safe to destroy the
529 * page, as neither references to it can be acquired at that point, nor
532 * cl_page is a state machine. States are enumerated in enum
533 * cl_page_state. Possible state transitions are enumerated in
534 * cl_page_state_set(). State transition process (i.e., actual changing of
535 * cl_page::cp_state field) is protected by the lock on the underlying VM
538 * Linux Kernel implementation.
540 * Binding between cl_page and cfs_page_t (which is a typedef for
541 * struct page) is implemented in the vvp layer. cl_page is attached to the
542 * ->private pointer of the struct page, together with the setting of
543 * PG_private bit in page->flags, and acquiring additional reference on the
544 * struct page (much like struct buffer_head, or any similar file system
545 * private data structures).
547 * PG_locked lock is used to implement both ownership and transfer
548 * synchronization, that is, page is VM-locked in CPS_{OWNED,PAGE{IN,OUT}}
549 * states. No additional references are acquired for the duration of the
552 * \warning *THIS IS NOT* the behavior expected by the Linux kernel, where
553 * write-out is "protected" by the special PG_writeback bit.
557 * States of cl_page. cl_page.c assumes particular order here.
559 * The page state machine is rather crude, as it doesn't recognize finer page
560 * states like "dirty" or "up to date". This is because such states are not
561 * always well defined for the whole stack (see, for example, the
562 * implementation of the read-ahead, that hides page up-to-dateness to track
563 * cache hits accurately). Such sub-states are maintained by the layers that
564 * are interested in them.
568 * Page is in the cache, un-owned. Page leaves cached state in the
571 * - [cl_page_state::CPS_OWNED] io comes across the page and
574 * - [cl_page_state::CPS_PAGEOUT] page is dirty, the
575 * req-formation engine decides that it wants to include this page
576 * into an cl_req being constructed, and yanks it from the cache;
578 * - [cl_page_state::CPS_FREEING] VM callback is executed to
579 * evict the page form the memory;
581 * \invariant cl_page::cp_owner == NULL && cl_page::cp_req == NULL
585 * Page is exclusively owned by some cl_io. Page may end up in this
586 * state as a result of
588 * - io creating new page and immediately owning it;
590 * - [cl_page_state::CPS_CACHED] io finding existing cached page
593 * - [cl_page_state::CPS_OWNED] io finding existing owned page
594 * and waiting for owner to release the page;
596 * Page leaves owned state in the following cases:
598 * - [cl_page_state::CPS_CACHED] io decides to leave the page in
599 * the cache, doing nothing;
601 * - [cl_page_state::CPS_PAGEIN] io starts read transfer for
604 * - [cl_page_state::CPS_PAGEOUT] io starts immediate write
605 * transfer for this page;
607 * - [cl_page_state::CPS_FREEING] io decides to destroy this
608 * page (e.g., as part of truncate or extent lock cancellation).
610 * \invariant cl_page::cp_owner != NULL && cl_page::cp_req == NULL
614 * Page is being written out, as a part of a transfer. This state is
615 * entered when req-formation logic decided that it wants this page to
616 * be sent through the wire _now_. Specifically, it means that once
617 * this state is achieved, transfer completion handler (with either
618 * success or failure indication) is guaranteed to be executed against
619 * this page independently of any locks and any scheduling decisions
620 * made by the hosting environment (that effectively means that the
621 * page is never put into cl_page_state::CPS_PAGEOUT state "in
622 * advance". This property is mentioned, because it is important when
623 * reasoning about possible dead-locks in the system). The page can
624 * enter this state as a result of
626 * - [cl_page_state::CPS_OWNED] an io requesting an immediate
627 * write-out of this page, or
629 * - [cl_page_state::CPS_CACHED] req-forming engine deciding
630 * that it has enough dirty pages cached to issue a "good"
633 * The page leaves cl_page_state::CPS_PAGEOUT state when the transfer
634 * is completed---it is moved into cl_page_state::CPS_CACHED state.
636 * Underlying VM page is locked for the duration of transfer.
638 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL
642 * Page is being read in, as a part of a transfer. This is quite
643 * similar to the cl_page_state::CPS_PAGEOUT state, except that
644 * read-in is always "immediate"---there is no such thing a sudden
645 * construction of read cl_req from cached, presumably not up to date,
648 * Underlying VM page is locked for the duration of transfer.
650 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL
654 * Page is being destroyed. This state is entered when client decides
655 * that page has to be deleted from its host object, as, e.g., a part
658 * Once this state is reached, there is no way to escape it.
660 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req == NULL
667 /** Host page, the page is from the host inode which the cl_page
671 /** Transient page, the transient cl_page is used to bind a cl_page
672 * to vmpage which is not belonging to the same object of cl_page.
673 * it is used in DirectIO, lockless IO and liblustre. */
678 * Flags maintained for every cl_page.
682 * Set when pagein completes. Used for debugging (read completes at
683 * most once for a page).
685 CPF_READ_COMPLETED = 1 << 0
689 * Fields are protected by the lock on cfs_page_t, except for atomics and
692 * \invariant Data type invariants are in cl_page_invariant(). Basically:
693 * cl_page::cp_parent and cl_page::cp_child are a well-formed double-linked
694 * list, consistent with the parent/child pointers in the cl_page::cp_obj and
695 * cl_page::cp_owner (when set).
698 /** Reference counter. */
700 /** An object this page is a part of. Immutable after creation. */
701 struct cl_object *cp_obj;
702 /** Logical page index within the object. Immutable after creation. */
704 /** List of slices. Immutable after creation. */
705 struct list_head cp_layers;
706 /** Parent page, NULL for top-level page. Immutable after creation. */
707 struct cl_page *cp_parent;
708 /** Lower-layer page. NULL for bottommost page. Immutable after
710 struct cl_page *cp_child;
712 * Page state. This field is const to avoid accidental update, it is
713 * modified only internally within cl_page.c. Protected by a VM lock.
715 const enum cl_page_state cp_state;
717 * Linkage of pages within some group. Protected by
718 * cl_page::cp_mutex. */
719 struct list_head cp_batch;
720 /** Mutex serializing membership of a page in a batch. */
721 struct mutex cp_mutex;
722 /** Linkage of pages within cl_req. */
723 struct list_head cp_flight;
724 /** Transfer error. */
728 * Page type. Only CPT_TRANSIENT is used so far. Immutable after
731 enum cl_page_type cp_type;
734 * Owning IO in cl_page_state::CPS_OWNED state. Sub-page can be owned
735 * by sub-io. Protected by a VM lock.
737 struct cl_io *cp_owner;
739 * Debug information, the task is owning the page.
743 * Owning IO request in cl_page_state::CPS_PAGEOUT and
744 * cl_page_state::CPS_PAGEIN states. This field is maintained only in
745 * the top-level pages. Protected by a VM lock.
747 struct cl_req *cp_req;
748 /** List of references to this page, for debugging. */
749 struct lu_ref cp_reference;
750 /** Link to an object, for debugging. */
751 struct lu_ref_link *cp_obj_ref;
752 /** Link to a queue, for debugging. */
753 struct lu_ref_link *cp_queue_ref;
754 /** Per-page flags from enum cl_page_flags. Protected by a VM lock. */
756 /** Assigned if doing a sync_io */
757 struct cl_sync_io *cp_sync_io;
761 * Per-layer part of cl_page.
763 * \see ccc_page, lov_page, osc_page
765 struct cl_page_slice {
766 struct cl_page *cpl_page;
768 * Object slice corresponding to this page slice. Immutable after
771 struct cl_object *cpl_obj;
772 const struct cl_page_operations *cpl_ops;
773 /** Linkage into cl_page::cp_layers. Immutable after creation. */
774 struct list_head cpl_linkage;
778 * Lock mode. For the client extent locks.
780 * \warning: cl_lock_mode_match() assumes particular ordering here.
785 * Mode of a lock that protects no data, and exists only as a
786 * placeholder. This is used for `glimpse' requests. A phantom lock
787 * might get promoted to real lock at some point.
796 * Requested transfer type.
806 * Per-layer page operations.
808 * Methods taking an \a io argument are for the activity happening in the
809 * context of given \a io. Page is assumed to be owned by that io, except for
810 * the obvious cases (like cl_page_operations::cpo_own()).
812 * \see vvp_page_ops, lov_page_ops, osc_page_ops
814 struct cl_page_operations {
816 * cl_page<->cfs_page_t methods. Only one layer in the stack has to
817 * implement these. Current code assumes that this functionality is
818 * provided by the topmost layer, see cl_page_disown0() as an example.
822 * \return the underlying VM page. Optional.
824 cfs_page_t *(*cpo_vmpage)(const struct lu_env *env,
825 const struct cl_page_slice *slice);
827 * Called when \a io acquires this page into the exclusive
828 * ownership. When this method returns, it is guaranteed that the is
829 * not owned by other io, and no transfer is going on against
833 * \see vvp_page_own(), lov_page_own()
835 void (*cpo_own)(const struct lu_env *env,
836 const struct cl_page_slice *slice, struct cl_io *io);
837 /** Called when ownership it yielded. Optional.
839 * \see cl_page_disown()
840 * \see vvp_page_disown()
842 void (*cpo_disown)(const struct lu_env *env,
843 const struct cl_page_slice *slice, struct cl_io *io);
845 * Called for a page that is already "owned" by \a io from VM point of
848 * \see cl_page_assume()
849 * \see vvp_page_assume(), lov_page_assume()
851 void (*cpo_assume)(const struct lu_env *env,
852 const struct cl_page_slice *slice, struct cl_io *io);
853 /** Dual to cl_page_operations::cpo_assume(). Optional. Called
854 * bottom-to-top when IO releases a page without actually unlocking
857 * \see cl_page_unassume()
858 * \see vvp_page_unassume()
860 void (*cpo_unassume)(const struct lu_env *env,
861 const struct cl_page_slice *slice,
864 * Announces whether the page contains valid data or not by @uptodate.
866 * \see cl_page_export()
867 * \see vvp_page_export()
869 void (*cpo_export)(const struct lu_env *env,
870 const struct cl_page_slice *slice, int uptodate);
872 * Unmaps page from the user space (if it is mapped).
874 * \see cl_page_unmap()
875 * \see vvp_page_unmap()
877 int (*cpo_unmap)(const struct lu_env *env,
878 const struct cl_page_slice *slice, struct cl_io *io);
880 * Checks whether underlying VM page is locked (in the suitable
881 * sense). Used for assertions.
883 * \retval -EBUSY: page is protected by a lock of a given mode;
884 * \retval -ENODATA: page is not protected by a lock;
885 * \retval 0: this layer cannot decide. (Should never happen.)
887 int (*cpo_is_vmlocked)(const struct lu_env *env,
888 const struct cl_page_slice *slice);
894 * Called when page is truncated from the object. Optional.
896 * \see cl_page_discard()
897 * \see vvp_page_discard(), osc_page_discard()
899 void (*cpo_discard)(const struct lu_env *env,
900 const struct cl_page_slice *slice,
903 * Called when page is removed from the cache, and is about to being
904 * destroyed. Optional.
906 * \see cl_page_delete()
907 * \see vvp_page_delete(), osc_page_delete()
909 void (*cpo_delete)(const struct lu_env *env,
910 const struct cl_page_slice *slice);
911 /** Destructor. Frees resources and slice itself. */
912 void (*cpo_fini)(const struct lu_env *env,
913 struct cl_page_slice *slice);
916 * Checks whether the page is protected by a cl_lock. This is a
917 * per-layer method, because certain layers have ways to check for the
918 * lock much more efficiently than through the generic locks scan, or
919 * implement locking mechanisms separate from cl_lock, e.g.,
920 * LL_FILE_GROUP_LOCKED in vvp. If \a pending is true, check for locks
921 * being canceled, or scheduled for cancellation as soon as the last
922 * user goes away, too.
924 * \retval -EBUSY: page is protected by a lock of a given mode;
925 * \retval -ENODATA: page is not protected by a lock;
926 * \retval 0: this layer cannot decide.
928 * \see cl_page_is_under_lock()
930 int (*cpo_is_under_lock)(const struct lu_env *env,
931 const struct cl_page_slice *slice,
935 * Optional debugging helper. Prints given page slice.
937 * \see cl_page_print()
939 int (*cpo_print)(const struct lu_env *env,
940 const struct cl_page_slice *slice,
941 void *cookie, lu_printer_t p);
945 * Transfer methods. See comment on cl_req for a description of
946 * transfer formation and life-cycle.
951 * Request type dependent vector of operations.
953 * Transfer operations depend on transfer mode (cl_req_type). To avoid
954 * passing transfer mode to each and every of these methods, and to
955 * avoid branching on request type inside of the methods, separate
956 * methods for cl_req_type:CRT_READ and cl_req_type:CRT_WRITE are
957 * provided. That is, method invocation usually looks like
959 * slice->cp_ops.io[req->crq_type].cpo_method(env, slice, ...);
963 * Called when a page is submitted for a transfer as a part of
966 * \return 0 : page is eligible for submission;
967 * \return -EALREADY : skip this page;
968 * \return -ve : error.
970 * \see cl_page_prep()
972 int (*cpo_prep)(const struct lu_env *env,
973 const struct cl_page_slice *slice,
976 * Completion handler. This is guaranteed to be eventually
977 * fired after cl_page_operations::cpo_prep() or
978 * cl_page_operations::cpo_make_ready() call.
980 * This method can be called in a non-blocking context. It is
981 * guaranteed however, that the page involved and its object
982 * are pinned in memory (and, hence, calling cl_page_put() is
985 * \see cl_page_completion()
987 void (*cpo_completion)(const struct lu_env *env,
988 const struct cl_page_slice *slice,
991 * Called when cached page is about to be added to the
992 * cl_req as a part of req formation.
994 * \return 0 : proceed with this page;
995 * \return -EAGAIN : skip this page;
996 * \return -ve : error.
998 * \see cl_page_make_ready()
1000 int (*cpo_make_ready)(const struct lu_env *env,
1001 const struct cl_page_slice *slice);
1003 * Announce that this page is to be written out
1004 * opportunistically, that is, page is dirty, it is not
1005 * necessary to start write-out transfer right now, but
1006 * eventually page has to be written out.
1008 * Main caller of this is the write path (see
1009 * vvp_io_commit_write()), using this method to build a
1010 * "transfer cache" from which large transfers are then
1011 * constructed by the req-formation engine.
1013 * \todo XXX it would make sense to add page-age tracking
1014 * semantics here, and to oblige the req-formation engine to
1015 * send the page out not later than it is too old.
1017 * \see cl_page_cache_add()
1019 int (*cpo_cache_add)(const struct lu_env *env,
1020 const struct cl_page_slice *slice,
1024 * Tell transfer engine that only [to, from] part of a page should be
1027 * This is used for immediate transfers.
1029 * \todo XXX this is not very good interface. It would be much better
1030 * if all transfer parameters were supplied as arguments to
1031 * cl_io_operations::cio_submit() call, but it is not clear how to do
1032 * this for page queues.
1034 * \see cl_page_clip()
1036 void (*cpo_clip)(const struct lu_env *env,
1037 const struct cl_page_slice *slice,
1040 * \pre the page was queued for transferring.
1041 * \post page is removed from client's pending list, or -EBUSY
1042 * is returned if it has already been in transferring.
1044 * This is one of seldom page operation which is:
1045 * 0. called from top level;
1046 * 1. don't have vmpage locked;
1047 * 2. every layer should synchronize execution of its ->cpo_cancel()
1048 * with completion handlers. Osc uses client obd lock for this
1049 * purpose. Based on there is no vvp_page_cancel and
1050 * lov_page_cancel(), cpo_cancel is defacto protected by client lock.
1052 * \see osc_page_cancel().
1054 int (*cpo_cancel)(const struct lu_env *env,
1055 const struct cl_page_slice *slice);
1060 * Helper macro, dumping detailed information about \a page into a log.
1062 #define CL_PAGE_DEBUG(mask, env, page, format, ...) \
1064 static DECLARE_LU_CDEBUG_PRINT_INFO(__info, mask); \
1066 if (cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1067 cl_page_print(env, &__info, lu_cdebug_printer, page); \
1068 CDEBUG(mask, format , ## __VA_ARGS__); \
1073 * Helper macro, dumping shorter information about \a page into a log.
1075 #define CL_PAGE_HEADER(mask, env, page, format, ...) \
1077 static DECLARE_LU_CDEBUG_PRINT_INFO(__info, mask); \
1079 if (cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1080 cl_page_header_print(env, &__info, lu_cdebug_printer, page); \
1081 CDEBUG(mask, format , ## __VA_ARGS__); \
1087 /** \addtogroup cl_lock cl_lock
1091 * Extent locking on the client.
1095 * The locking model of the new client code is built around
1099 * data-type representing an extent lock on a regular file. cl_lock is a
1100 * layered object (much like cl_object and cl_page), it consists of a header
1101 * (struct cl_lock) and a list of layers (struct cl_lock_slice), linked to
1102 * cl_lock::cll_layers list through cl_lock_slice::cls_linkage.
1104 * All locks for a given object are linked into cl_object_header::coh_locks
1105 * list (protected by cl_object_header::coh_lock_guard spin-lock) through
1106 * cl_lock::cll_linkage. Currently this list is not sorted in any way. We can
1107 * sort it in starting lock offset, or use altogether different data structure
1110 * Typical cl_lock consists of the two layers:
1112 * - vvp_lock (vvp specific data), and
1113 * - lov_lock (lov specific data).
1115 * lov_lock contains an array of sub-locks. Each of these sub-locks is a
1116 * normal cl_lock: it has a header (struct cl_lock) and a list of layers:
1118 * - lovsub_lock, and
1121 * Each sub-lock is associated with a cl_object (representing stripe
1122 * sub-object or the file to which top-level cl_lock is associated to), and is
1123 * linked into that cl_object::coh_locks. In this respect cl_lock is similar to
1124 * cl_object (that at lov layer also fans out into multiple sub-objects), and
1125 * is different from cl_page, that doesn't fan out (there is usually exactly
1126 * one osc_page for every vvp_page). We shall call vvp-lov portion of the lock
1127 * a "top-lock" and its lovsub-osc portion a "sub-lock".
1131 * cl_lock is reference counted. When reference counter drops to 0, lock is
1132 * placed in the cache, except when lock is in CLS_FREEING state. CLS_FREEING
1133 * lock is destroyed when last reference is released. Referencing between
1134 * top-lock and its sub-locks is described in the lov documentation module.
1138 * Also, cl_lock is a state machine. This requires some clarification. One of
1139 * the goals of client IO re-write was to make IO path non-blocking, or at
1140 * least to make it easier to make it non-blocking in the future. Here
1141 * `non-blocking' means that when a system call (read, write, truncate)
1142 * reaches a situation where it has to wait for a communication with the
1143 * server, it should --instead of waiting-- remember its current state and
1144 * switch to some other work. E.g,. instead of waiting for a lock enqueue,
1145 * client should proceed doing IO on the next stripe, etc. Obviously this is
1146 * rather radical redesign, and it is not planned to be fully implemented at
1147 * this time, instead we are putting some infrastructure in place, that would
1148 * make it easier to do asynchronous non-blocking IO easier in the
1149 * future. Specifically, where old locking code goes to sleep (waiting for
1150 * enqueue, for example), new code returns cl_lock_transition::CLO_WAIT. When
1151 * enqueue reply comes, its completion handler signals that lock state-machine
1152 * is ready to transit to the next state. There is some generic code in
1153 * cl_lock.c that sleeps, waiting for these signals. As a result, for users of
1154 * this cl_lock.c code, it looks like locking is done in normal blocking
1155 * fashion, and it the same time it is possible to switch to the non-blocking
1156 * locking (simply by returning cl_lock_transition::CLO_WAIT from cl_lock.c
1159 * For a description of state machine states and transitions see enum
1162 * There are two ways to restrict a set of states which lock might move to:
1164 * - placing a "hold" on a lock guarantees that lock will not be moved
1165 * into cl_lock_state::CLS_FREEING state until hold is released. Hold
1166 * can be only acquired on a lock that is not in
1167 * cl_lock_state::CLS_FREEING. All holds on a lock are counted in
1168 * cl_lock::cll_holds. Hold protects lock from cancellation and
1169 * destruction. Requests to cancel and destroy a lock on hold will be
1170 * recorded, but only honored when last hold on a lock is released;
1172 * - placing a "user" on a lock guarantees that lock will not leave
1173 * cl_lock_state::CLS_NEW, cl_lock_state::CLS_QUEUING,
1174 * cl_lock_state::CLS_ENQUEUED and cl_lock_state::CLS_HELD set of
1175 * states, once it enters this set. That is, if a user is added onto a
1176 * lock in a state not from this set, it doesn't immediately enforce
1177 * lock to move to this set, but once lock enters this set it will
1178 * remain there until all users are removed. Lock users are counted in
1179 * cl_lock::cll_users.
1181 * User is used to assure that lock is not canceled or destroyed while
1182 * it is being enqueued, or actively used by some IO.
1184 * Currently, a user always comes with a hold (cl_lock_invariant()
1185 * checks that a number of holds is not less than a number of users).
1189 * This is how lock state-machine operates. struct cl_lock contains a mutex
1190 * cl_lock::cll_guard that protects struct fields.
1192 * - mutex is taken, and cl_lock::cll_state is examined.
1194 * - for every state there are possible target states where lock can move
1195 * into. They are tried in order. Attempts to move into next state are
1196 * done by _try() functions in cl_lock.c:cl_{enqueue,unlock,wait}_try().
1198 * - if the transition can be performed immediately, state is changed,
1199 * and mutex is released.
1201 * - if the transition requires blocking, _try() function returns
1202 * cl_lock_transition::CLO_WAIT. Caller unlocks mutex and goes to
1203 * sleep, waiting for possibility of lock state change. It is woken
1204 * up when some event occurs, that makes lock state change possible
1205 * (e.g., the reception of the reply from the server), and repeats
1208 * Top-lock and sub-lock has separate mutexes and the latter has to be taken
1209 * first to avoid dead-lock.
1211 * To see an example of interaction of all these issues, take a look at the
1212 * lov_cl.c:lov_lock_enqueue() function. It is called as a part of
1213 * cl_enqueue_try(), and tries to advance top-lock to ENQUEUED state, by
1214 * advancing state-machines of its sub-locks (lov_lock_enqueue_one()). Note
1215 * also, that it uses trylock to grab sub-lock mutex to avoid dead-lock. It
1216 * also has to handle CEF_ASYNC enqueue, when sub-locks enqueues have to be
1217 * done in parallel, rather than one after another (this is used for glimpse
1218 * locks, that cannot dead-lock).
1220 * INTERFACE AND USAGE
1222 * struct cl_lock_operations provide a number of call-backs that are invoked
1223 * when events of interest occurs. Layers can intercept and handle glimpse,
1224 * blocking, cancel ASTs and a reception of the reply from the server.
1226 * One important difference with the old client locking model is that new
1227 * client has a representation for the top-lock, whereas in the old code only
1228 * sub-locks existed as real data structures and file-level locks are
1229 * represented by "request sets" that are created and destroyed on each and
1230 * every lock creation.
1232 * Top-locks are cached, and can be found in the cache by the system calls. It
1233 * is possible that top-lock is in cache, but some of its sub-locks were
1234 * canceled and destroyed. In that case top-lock has to be enqueued again
1235 * before it can be used.
1237 * Overall process of the locking during IO operation is as following:
1239 * - once parameters for IO are setup in cl_io, cl_io_operations::cio_lock()
1240 * is called on each layer. Responsibility of this method is to add locks,
1241 * needed by a given layer into cl_io.ci_lockset.
1243 * - once locks for all layers were collected, they are sorted to avoid
1244 * dead-locks (cl_io_locks_sort()), and enqueued.
1246 * - when all locks are acquired, IO is performed;
1248 * - locks are released into cache.
1250 * Striping introduces major additional complexity into locking. The
1251 * fundamental problem is that it is generally unsafe to actively use (hold)
1252 * two locks on the different OST servers at the same time, as this introduces
1253 * inter-server dependency and can lead to cascading evictions.
1255 * Basic solution is to sub-divide large read/write IOs into smaller pieces so
1256 * that no multi-stripe locks are taken (note that this design abandons POSIX
1257 * read/write semantics). Such pieces ideally can be executed concurrently. At
1258 * the same time, certain types of IO cannot be sub-divived, without
1259 * sacrificing correctness. This includes:
1261 * - O_APPEND write, where [0, EOF] lock has to be taken, to guarantee
1264 * - ftruncate(fd, offset), where [offset, EOF] lock has to be taken.
1266 * Also, in the case of read(fd, buf, count) or write(fd, buf, count), where
1267 * buf is a part of memory mapped Lustre file, a lock or locks protecting buf
1268 * has to be held together with the usual lock on [offset, offset + count].
1270 * As multi-stripe locks have to be allowed, it makes sense to cache them, so
1271 * that, for example, a sequence of O_APPEND writes can proceed quickly
1272 * without going down to the individual stripes to do lock matching. On the
1273 * other hand, multi-stripe locks shouldn't be used by normal read/write
1274 * calls. To achieve this, every layer can implement ->clo_fits_into() method,
1275 * that is called by lock matching code (cl_lock_lookup()), and that can be
1276 * used to selectively disable matching of certain locks for certain IOs. For
1277 * exmaple, lov layer implements lov_lock_fits_into() that allow multi-stripe
1278 * locks to be matched only for truncates and O_APPEND writes.
1280 * Interaction with DLM
1282 * In the expected setup, cl_lock is ultimately backed up by a collection of
1283 * DLM locks (struct ldlm_lock). Association between cl_lock and DLM lock is
1284 * implemented in osc layer, that also matches DLM events (ASTs, cancellation,
1285 * etc.) into cl_lock_operation calls. See struct osc_lock for a more detailed
1286 * description of interaction with DLM.
1292 struct cl_lock_descr {
1293 /** Object this lock is granted for. */
1294 struct cl_object *cld_obj;
1295 /** Index of the first page protected by this lock. */
1297 /** Index of the last page (inclusive) protected by this lock. */
1299 /** Group ID, for group lock */
1302 enum cl_lock_mode cld_mode;
1305 #define DDESCR "%s(%d):[%lu, %lu]"
1306 #define PDESCR(descr) \
1307 cl_lock_mode_name((descr)->cld_mode), (descr)->cld_mode, \
1308 (descr)->cld_start, (descr)->cld_end
1310 const char *cl_lock_mode_name(const enum cl_lock_mode mode);
1313 * Lock state-machine states.
1318 * Possible state transitions:
1320 * +------------------>NEW
1322 * | | cl_enqueue_try()
1324 * | cl_unuse_try() V
1325 * | +--------------QUEUING (*)
1327 * | | | cl_enqueue_try()
1329 * | | cl_unuse_try() V
1330 * sub-lock | +-------------ENQUEUED (*)
1332 * | | | cl_wait_try()
1337 * | | HELD<---------+
1340 * | | cl_unuse_try() | |
1343 * | +------------>UNLOCKING (*) | lock found
1345 * | cl_unuse_try() | |
1347 * | | | cl_use_try()
1349 * +------------------CACHED---------+
1358 * In states marked with (*) transition to the same state (i.e., a loop
1359 * in the diagram) is possible.
1361 * (R) is the point where Receive call-back is invoked: it allows layers
1362 * to handle arrival of lock reply.
1364 * (C) is the point where Cancellation call-back is invoked.
1366 * Transition to FREEING state is possible from any other state in the
1367 * diagram in case of unrecoverable error.
1371 * These states are for individual cl_lock object. Top-lock and its sub-locks
1372 * can be in the different states. Another way to say this is that we have
1373 * nested state-machines.
1375 * Separate QUEUING and ENQUEUED states are needed to support non-blocking
1376 * operation for locks with multiple sub-locks. Imagine lock on a file F, that
1377 * intersects 3 stripes S0, S1, and S2. To enqueue F client has to send
1378 * enqueue to S0, wait for its completion, then send enqueue for S1, wait for
1379 * its completion and at last enqueue lock for S2, and wait for its
1380 * completion. In that case, top-lock is in QUEUING state while S0, S1 are
1381 * handled, and is in ENQUEUED state after enqueue to S2 has been sent (note
1382 * that in this case, sub-locks move from state to state, and top-lock remains
1383 * in the same state).
1385 * Separate UNLOCKING state is needed to maintain an invariant that in HELD
1386 * state lock is immediately ready for use.
1388 enum cl_lock_state {
1390 * Lock that wasn't yet enqueued
1394 * Enqueue is in progress, blocking for some intermediate interaction
1395 * with the other side.
1399 * Lock is fully enqueued, waiting for server to reply when it is
1404 * Lock granted, actively used by some IO.
1408 * Lock is in the transition from CLS_HELD to CLS_CACHED. Lock is in
1409 * this state only while cl_unuse() is executing against it.
1413 * Lock granted, not used.
1417 * Lock is being destroyed.
1423 enum cl_lock_flags {
1425 * lock has been cancelled. This flag is never cleared once set (by
1426 * cl_lock_cancel0()).
1428 CLF_CANCELLED = 1 << 0,
1429 /** cancellation is pending for this lock. */
1430 CLF_CANCELPEND = 1 << 1,
1431 /** destruction is pending for this lock. */
1432 CLF_DOOMED = 1 << 2,
1433 /** State update is pending. */
1440 * Lock closure is a collection of locks (both top-locks and sub-locks) that
1441 * might be updated in a result of an operation on a certain lock (which lock
1442 * this is a closure of).
1444 * Closures are needed to guarantee dead-lock freedom in the presence of
1446 * - nested state-machines (top-lock state-machine composed of sub-lock
1447 * state-machines), and
1449 * - shared sub-locks.
1451 * Specifically, many operations, such as lock enqueue, wait, unlock,
1452 * etc. start from a top-lock, and then operate on a sub-locks of this
1453 * top-lock, holding a top-lock mutex. When sub-lock state changes as a result
1454 * of such operation, this change has to be propagated to all top-locks that
1455 * share this sub-lock. Obviously, no natural lock ordering (e.g.,
1456 * top-to-bottom or bottom-to-top) captures this scenario, so try-locking has
1457 * to be used. Lock closure systematizes this try-and-repeat logic.
1459 struct cl_lock_closure {
1461 * Lock that is mutexed when closure construction is started. When
1462 * closure in is `wait' mode (cl_lock_closure::clc_wait), mutex on
1463 * origin is released before waiting.
1465 struct cl_lock *clc_origin;
1467 * List of enclosed locks, so far. Locks are linked here through
1468 * cl_lock::cll_inclosure.
1470 struct list_head clc_list;
1472 * True iff closure is in a `wait' mode. This determines what
1473 * cl_lock_enclosure() does when a lock L to be added to the closure
1474 * is currently mutexed by some other thread.
1476 * If cl_lock_closure::clc_wait is not set, then closure construction
1477 * fails with CLO_REPEAT immediately.
1479 * In wait mode, cl_lock_enclosure() waits until next attempt to build
1480 * a closure might succeed. To this end it releases an origin mutex
1481 * (cl_lock_closure::clc_origin), that has to be the only lock mutex
1482 * owned by the current thread, and then waits on L mutex (by grabbing
1483 * it and immediately releasing), before returning CLO_REPEAT to the
1487 /** Number of locks in the closure. */
1492 * Layered client lock.
1495 /** Reference counter. */
1497 /** List of slices. Immutable after creation. */
1498 struct list_head cll_layers;
1500 * Linkage into cl_lock::cll_descr::cld_obj::coh_locks list. Protected
1501 * by cl_lock::cll_descr::cld_obj::coh_lock_guard.
1503 struct list_head cll_linkage;
1505 * Parameters of this lock. Protected by
1506 * cl_lock::cll_descr::cld_obj::coh_lock_guard nested within
1507 * cl_lock::cll_guard. Modified only on lock creation and in
1510 struct cl_lock_descr cll_descr;
1511 /** Protected by cl_lock::cll_guard. */
1512 enum cl_lock_state cll_state;
1513 /** signals state changes. */
1516 * Recursive lock, most fields in cl_lock{} are protected by this.
1518 * Locking rules: this mutex is never held across network
1519 * communication, except when lock is being canceled.
1521 * Lock ordering: a mutex of a sub-lock is taken first, then a mutex
1522 * on a top-lock. Other direction is implemented through a
1523 * try-lock-repeat loop. Mutices of unrelated locks can be taken only
1526 * \see osc_lock_enqueue_wait(), lov_lock_cancel(), lov_sublock_wait().
1528 struct mutex cll_guard;
1529 cfs_task_t *cll_guarder;
1534 * Number of holds on a lock. A hold prevents a lock from being
1535 * canceled and destroyed. Protected by cl_lock::cll_guard.
1537 * \see cl_lock_hold(), cl_lock_unhold(), cl_lock_release()
1541 * Number of lock users. Valid in cl_lock_state::CLS_HELD state
1542 * only. Lock user pins lock in CLS_HELD state. Protected by
1543 * cl_lock::cll_guard.
1545 * \see cl_wait(), cl_unuse().
1549 * Flag bit-mask. Values from enum cl_lock_flags. Updates are
1550 * protected by cl_lock::cll_guard.
1552 unsigned long cll_flags;
1554 * A linkage into a list of locks in a closure.
1556 * \see cl_lock_closure
1558 struct list_head cll_inclosure;
1560 * A list of references to this lock, for debugging.
1562 struct lu_ref cll_reference;
1564 * A list of holds on this lock, for debugging.
1566 struct lu_ref cll_holders;
1568 * A reference for cl_lock::cll_descr::cld_obj. For debugging.
1570 struct lu_ref_link *cll_obj_ref;
1571 #ifdef CONFIG_LOCKDEP
1572 /* "dep_map" name is assumed by lockdep.h macros. */
1573 struct lockdep_map dep_map;
1578 * Per-layer part of cl_lock
1580 * \see ccc_lock, lov_lock, lovsub_lock, osc_lock
1582 struct cl_lock_slice {
1583 struct cl_lock *cls_lock;
1584 /** Object slice corresponding to this lock slice. Immutable after
1586 struct cl_object *cls_obj;
1587 const struct cl_lock_operations *cls_ops;
1588 /** Linkage into cl_lock::cll_layers. Immutable after creation. */
1589 struct list_head cls_linkage;
1593 * Possible (non-error) return values of ->clo_{enqueue,wait,unlock}().
1595 * NOTE: lov_subresult() depends on ordering here.
1597 enum cl_lock_transition {
1598 /** operation cannot be completed immediately. Wait for state change. */
1600 /** operation had to release lock mutex, restart. */
1606 * \see vvp_lock_ops, lov_lock_ops, lovsub_lock_ops, osc_lock_ops
1608 struct cl_lock_operations {
1610 * \name statemachine
1612 * State machine transitions. These 3 methods are called to transfer
1613 * lock from one state to another, as described in the commentary
1614 * above enum #cl_lock_state.
1616 * \retval 0 this layer has nothing more to do to before
1617 * transition to the target state happens;
1619 * \retval CLO_REPEAT method had to release and re-acquire cl_lock
1620 * mutex, repeat invocation of transition method
1621 * across all layers;
1623 * \retval CLO_WAIT this layer cannot move to the target state
1624 * immediately, as it has to wait for certain event
1625 * (e.g., the communication with the server). It
1626 * is guaranteed, that when the state transfer
1627 * becomes possible, cl_lock::cll_wq wait-queue
1628 * is signaled. Caller can wait for this event by
1629 * calling cl_lock_state_wait();
1631 * \retval -ve failure, abort state transition, move the lock
1632 * into cl_lock_state::CLS_FREEING state, and set
1633 * cl_lock::cll_error.
1635 * Once all layers voted to agree to transition (by returning 0), lock
1636 * is moved into corresponding target state. All state transition
1637 * methods are optional.
1641 * Attempts to enqueue the lock. Called top-to-bottom.
1643 * \see ccc_lock_enqueue(), lov_lock_enqueue(), lovsub_lock_enqueue(),
1644 * \see osc_lock_enqueue()
1646 int (*clo_enqueue)(const struct lu_env *env,
1647 const struct cl_lock_slice *slice,
1648 struct cl_io *io, __u32 enqflags);
1650 * Attempts to wait for enqueue result. Called top-to-bottom.
1652 * \see ccc_lock_wait(), lov_lock_wait(), osc_lock_wait()
1654 int (*clo_wait)(const struct lu_env *env,
1655 const struct cl_lock_slice *slice);
1657 * Attempts to unlock the lock. Called bottom-to-top. In addition to
1658 * usual return values of lock state-machine methods, this can return
1659 * -ESTALE to indicate that lock cannot be returned to the cache, and
1660 * has to be re-initialized.
1662 * \see ccc_lock_unlock(), lov_lock_unlock(), osc_lock_unlock()
1664 int (*clo_unuse)(const struct lu_env *env,
1665 const struct cl_lock_slice *slice);
1667 * Notifies layer that cached lock is started being used.
1669 * \pre lock->cll_state == CLS_CACHED
1671 * \see lov_lock_use(), osc_lock_use()
1673 int (*clo_use)(const struct lu_env *env,
1674 const struct cl_lock_slice *slice);
1675 /** @} statemachine */
1677 * A method invoked when lock state is changed (as a result of state
1678 * transition). This is used, for example, to track when the state of
1679 * a sub-lock changes, to propagate this change to the corresponding
1680 * top-lock. Optional
1682 * \see lovsub_lock_state()
1684 void (*clo_state)(const struct lu_env *env,
1685 const struct cl_lock_slice *slice,
1686 enum cl_lock_state st);
1688 * Returns true, iff given lock is suitable for the given io, idea
1689 * being, that there are certain "unsafe" locks, e.g., ones acquired
1690 * for O_APPEND writes, that we don't want to re-use for a normal
1691 * write, to avoid the danger of cascading evictions. Optional. Runs
1692 * under cl_object_header::coh_lock_guard.
1694 * XXX this should take more information about lock needed by
1695 * io. Probably lock description or something similar.
1697 * \see lov_fits_into()
1699 int (*clo_fits_into)(const struct lu_env *env,
1700 const struct cl_lock_slice *slice,
1701 const struct cl_lock_descr *need,
1702 const struct cl_io *io);
1705 * Asynchronous System Traps. All of then are optional, all are
1706 * executed bottom-to-top.
1711 * Cancellation callback. Cancel a lock voluntarily, or under
1712 * the request of server.
1714 void (*clo_cancel)(const struct lu_env *env,
1715 const struct cl_lock_slice *slice);
1717 * Lock weighting ast. Executed to estimate how precious this lock
1718 * is. The sum of results across all layers is used to determine
1719 * whether lock worth keeping in cache given present memory usage.
1721 * \see osc_lock_weigh(), vvp_lock_weigh(), lovsub_lock_weigh().
1723 unsigned long (*clo_weigh)(const struct lu_env *env,
1724 const struct cl_lock_slice *slice);
1728 * \see lovsub_lock_closure()
1730 int (*clo_closure)(const struct lu_env *env,
1731 const struct cl_lock_slice *slice,
1732 struct cl_lock_closure *closure);
1734 * Executed top-to-bottom when lock description changes (e.g., as a
1735 * result of server granting more generous lock than was requested).
1737 * \see lovsub_lock_modify()
1739 int (*clo_modify)(const struct lu_env *env,
1740 const struct cl_lock_slice *slice,
1741 const struct cl_lock_descr *updated);
1743 * Notifies layers (bottom-to-top) that lock is going to be
1744 * destroyed. Responsibility of layers is to prevent new references on
1745 * this lock from being acquired once this method returns.
1747 * This can be called multiple times due to the races.
1749 * \see cl_lock_delete()
1750 * \see osc_lock_delete(), lovsub_lock_delete()
1752 void (*clo_delete)(const struct lu_env *env,
1753 const struct cl_lock_slice *slice);
1755 * Destructor. Frees resources and the slice.
1757 * \see ccc_lock_fini(), lov_lock_fini(), lovsub_lock_fini(),
1758 * \see osc_lock_fini()
1760 void (*clo_fini)(const struct lu_env *env, struct cl_lock_slice *slice);
1762 * Optional debugging helper. Prints given lock slice.
1764 int (*clo_print)(const struct lu_env *env,
1765 void *cookie, lu_printer_t p,
1766 const struct cl_lock_slice *slice);
1769 #define CL_LOCK_DEBUG(mask, env, lock, format, ...) \
1771 static DECLARE_LU_CDEBUG_PRINT_INFO(__info, mask); \
1773 if (cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1774 cl_lock_print(env, &__info, lu_cdebug_printer, lock); \
1775 CDEBUG(mask, format , ## __VA_ARGS__); \
1781 /** \addtogroup cl_page_list cl_page_list
1782 * Page list used to perform collective operations on a group of pages.
1784 * Pages are added to the list one by one. cl_page_list acquires a reference
1785 * for every page in it. Page list is used to perform collective operations on
1788 * - submit pages for an immediate transfer,
1790 * - own pages on behalf of certain io (waiting for each page in turn),
1794 * When list is finalized, it releases references on all pages it still has.
1796 * \todo XXX concurrency control.
1800 struct cl_page_list {
1802 struct list_head pl_pages;
1803 cfs_task_t *pl_owner;
1806 /** \addtogroup cl_page_list cl_page_list
1807 * A 2-queue of pages. A convenience data-type for common use case, 2-queue
1808 * contains an incoming page list and an outgoing page list.
1811 struct cl_page_list c2_qin;
1812 struct cl_page_list c2_qout;
1815 /** @} cl_page_list */
1817 /** \addtogroup cl_io cl_io
1822 * cl_io represents a high level I/O activity like
1823 * read(2)/write(2)/truncate(2) system call, or cancellation of an extent
1826 * cl_io is a layered object, much like cl_{object,page,lock} but with one
1827 * important distinction. We want to minimize number of calls to the allocator
1828 * in the fast path, e.g., in the case of read(2) when everything is cached:
1829 * client already owns the lock over region being read, and data are cached
1830 * due to read-ahead. To avoid allocation of cl_io layers in such situations,
1831 * per-layer io state is stored in the session, associated with the io, see
1832 * struct {vvp,lov,osc}_io for example. Sessions allocation is amortized
1833 * by using free-lists, see cl_env_get().
1835 * There is a small predefined number of possible io types, enumerated in enum
1838 * cl_io is a state machine, that can be advanced concurrently by the multiple
1839 * threads. It is up to these threads to control the concurrency and,
1840 * specifically, to detect when io is done, and its state can be safely
1843 * For read/write io overall execution plan is as following:
1845 * (0) initialize io state through all layers;
1847 * (1) loop: prepare chunk of work to do
1849 * (2) call all layers to collect locks they need to process current chunk
1851 * (3) sort all locks to avoid dead-locks, and acquire them
1853 * (4) process the chunk: call per-page methods
1854 * (cl_io_operations::cio_read_page() for read,
1855 * cl_io_operations::cio_prepare_write(),
1856 * cl_io_operations::cio_commit_write() for write)
1862 * To implement the "parallel IO mode", lov layer creates sub-io's (lazily to
1863 * address allocation efficiency issues mentioned above), and returns with the
1864 * special error condition from per-page method when current sub-io has to
1865 * block. This causes io loop to be repeated, and lov switches to the next
1866 * sub-io in its cl_io_operations::cio_iter_init() implementation.
1871 /** read system call */
1873 /** write system call */
1875 /** truncate system call */
1878 * page fault handling
1882 * Miscellaneous io. This is used for occasional io activity that
1883 * doesn't fit into other types. Currently this is used for:
1885 * - cancellation of an extent lock. This io exists as a context
1886 * to write dirty pages from under the lock being canceled back
1889 * - VM induced page write-out. An io context for writing page out
1890 * for memory cleansing;
1892 * - glimpse. An io context to acquire glimpse lock.
1894 * - grouplock. An io context to acquire group lock.
1896 * CIT_MISC io is used simply as a context in which locks and pages
1897 * are manipulated. Such io has no internal "process", that is,
1898 * cl_io_loop() is never called for it.
1905 * States of cl_io state machine
1908 /** Not initialized. */
1912 /** IO iteration started. */
1916 /** Actual IO is in progress. */
1918 /** IO for the current iteration finished. */
1920 /** Locks released. */
1922 /** Iteration completed. */
1924 /** cl_io finalized. */
1928 enum cl_req_priority {
1934 * IO state private for a layer.
1936 * This is usually embedded into layer session data, rather than allocated
1939 * \see vvp_io, lov_io, osc_io, ccc_io
1941 struct cl_io_slice {
1942 struct cl_io *cis_io;
1943 /** corresponding object slice. Immutable after creation. */
1944 struct cl_object *cis_obj;
1945 /** io operations. Immutable after creation. */
1946 const struct cl_io_operations *cis_iop;
1948 * linkage into a list of all slices for a given cl_io, hanging off
1949 * cl_io::ci_layers. Immutable after creation.
1951 struct list_head cis_linkage;
1956 * Per-layer io operations.
1957 * \see vvp_io_ops, lov_io_ops, lovsub_io_ops, osc_io_ops
1959 struct cl_io_operations {
1961 * Vector of io state transition methods for every io type.
1963 * \see cl_page_operations::io
1967 * Prepare io iteration at a given layer.
1969 * Called top-to-bottom at the beginning of each iteration of
1970 * "io loop" (if it makes sense for this type of io). Here
1971 * layer selects what work it will do during this iteration.
1973 * \see cl_io_operations::cio_iter_fini()
1975 int (*cio_iter_init) (const struct lu_env *env,
1976 const struct cl_io_slice *slice);
1978 * Finalize io iteration.
1980 * Called bottom-to-top at the end of each iteration of "io
1981 * loop". Here layers can decide whether IO has to be
1984 * \see cl_io_operations::cio_iter_init()
1986 void (*cio_iter_fini) (const struct lu_env *env,
1987 const struct cl_io_slice *slice);
1989 * Collect locks for the current iteration of io.
1991 * Called top-to-bottom to collect all locks necessary for
1992 * this iteration. This methods shouldn't actually enqueue
1993 * anything, instead it should post a lock through
1994 * cl_io_lock_add(). Once all locks are collected, they are
1995 * sorted and enqueued in the proper order.
1997 int (*cio_lock) (const struct lu_env *env,
1998 const struct cl_io_slice *slice);
2000 * Finalize unlocking.
2002 * Called bottom-to-top to finish layer specific unlocking
2003 * functionality, after generic code released all locks
2004 * acquired by cl_io_operations::cio_lock().
2006 void (*cio_unlock)(const struct lu_env *env,
2007 const struct cl_io_slice *slice);
2009 * Start io iteration.
2011 * Once all locks are acquired, called top-to-bottom to
2012 * commence actual IO. In the current implementation,
2013 * top-level vvp_io_{read,write}_start() does all the work
2014 * synchronously by calling generic_file_*(), so other layers
2015 * are called when everything is done.
2017 int (*cio_start)(const struct lu_env *env,
2018 const struct cl_io_slice *slice);
2020 * Called top-to-bottom at the end of io loop. Here layer
2021 * might wait for an unfinished asynchronous io.
2023 void (*cio_end) (const struct lu_env *env,
2024 const struct cl_io_slice *slice);
2026 * Called bottom-to-top to notify layers that read/write IO
2027 * iteration finished, with \a nob bytes transferred.
2029 void (*cio_advance)(const struct lu_env *env,
2030 const struct cl_io_slice *slice,
2033 * Called once per io, bottom-to-top to release io resources.
2035 void (*cio_fini) (const struct lu_env *env,
2036 const struct cl_io_slice *slice);
2040 * Submit pages from \a queue->c2_qin for IO, and move
2041 * successfully submitted pages into \a queue->c2_qout. Return
2042 * non-zero if failed to submit even the single page. If
2043 * submission failed after some pages were moved into \a
2044 * queue->c2_qout, completion callback with non-zero ioret is
2047 int (*cio_submit)(const struct lu_env *env,
2048 const struct cl_io_slice *slice,
2049 enum cl_req_type crt,
2050 struct cl_2queue *queue,
2051 enum cl_req_priority priority);
2054 * Read missing page.
2056 * Called by a top-level cl_io_operations::op[CIT_READ]::cio_start()
2057 * method, when it hits not-up-to-date page in the range. Optional.
2059 * \pre io->ci_type == CIT_READ
2061 int (*cio_read_page)(const struct lu_env *env,
2062 const struct cl_io_slice *slice,
2063 const struct cl_page_slice *page);
2065 * Prepare write of a \a page. Called bottom-to-top by a top-level
2066 * cl_io_operations::op[CIT_WRITE]::cio_start() to prepare page for
2067 * get data from user-level buffer.
2069 * \pre io->ci_type == CIT_WRITE
2071 * \see vvp_io_prepare_write(), lov_io_prepare_write(),
2072 * osc_io_prepare_write().
2074 int (*cio_prepare_write)(const struct lu_env *env,
2075 const struct cl_io_slice *slice,
2076 const struct cl_page_slice *page,
2077 unsigned from, unsigned to);
2080 * \pre io->ci_type == CIT_WRITE
2082 * \see vvp_io_commit_write(), lov_io_commit_write(),
2083 * osc_io_commit_write().
2085 int (*cio_commit_write)(const struct lu_env *env,
2086 const struct cl_io_slice *slice,
2087 const struct cl_page_slice *page,
2088 unsigned from, unsigned to);
2090 * Optional debugging helper. Print given io slice.
2092 int (*cio_print)(const struct lu_env *env, void *cookie,
2093 lu_printer_t p, const struct cl_io_slice *slice);
2097 * Flags to lock enqueue procedure.
2102 * instruct server to not block, if conflicting lock is found. Instead
2103 * -EWOULDBLOCK is returned immediately.
2105 CEF_NONBLOCK = 0x00000001,
2107 * take lock asynchronously (out of order), as it cannot
2108 * deadlock. This is for LDLM_FL_HAS_INTENT locks used for glimpsing.
2110 CEF_ASYNC = 0x00000002,
2112 * tell the server to instruct (though a flag in the blocking ast) an
2113 * owner of the conflicting lock, that it can drop dirty pages
2114 * protected by this lock, without sending them to the server.
2116 CEF_DISCARD_DATA = 0x00000004,
2118 * tell the sub layers that it must be a `real' lock. This is used for
2119 * mmapped-buffer locks and glimpse locks that must be never converted
2120 * into lockless mode.
2122 * \see vvp_mmap_locks(), cl_glimpse_lock().
2124 CEF_MUST = 0x00000008,
2126 * tell the sub layers that never request a `real' lock. This flag is
2127 * not used currently.
2129 * cl_io::ci_lockreq and CEF_{MUST,NEVER} flags specify lockless
2130 * conversion policy: ci_lockreq describes generic information of lock
2131 * requirement for this IO, especially for locks which belong to the
2132 * object doing IO; however, lock itself may have precise requirements
2133 * that are described by the enqueue flags.
2135 CEF_NEVER = 0x00000010,
2137 * mask of enq_flags.
2139 CEF_MASK = 0x0000001f
2143 * Link between lock and io. Intermediate structure is needed, because the
2144 * same lock can be part of multiple io's simultaneously.
2146 struct cl_io_lock_link {
2147 /** linkage into one of cl_lockset lists. */
2148 struct list_head cill_linkage;
2149 struct cl_lock_descr cill_descr;
2150 struct cl_lock *cill_lock;
2152 * flags to enqueue lock for this IO. A combination of bit-flags from
2153 * enum cl_enq_flags.
2155 __u32 cill_enq_flags;
2156 /** optional destructor */
2157 void (*cill_fini)(const struct lu_env *env,
2158 struct cl_io_lock_link *link);
2162 * Lock-set represents a collection of locks, that io needs at a
2163 * time. Generally speaking, client tries to avoid holding multiple locks when
2166 * - holding extent locks over multiple ost's introduces the danger of
2167 * "cascading timeouts";
2169 * - holding multiple locks over the same ost is still dead-lock prone,
2170 * see comment in osc_lock_enqueue(),
2172 * but there are certain situations where this is unavoidable:
2174 * - O_APPEND writes have to take [0, EOF] lock for correctness;
2176 * - truncate has to take [new-size, EOF] lock for correctness;
2178 * - SNS has to take locks across full stripe for correctness;
2180 * - in the case when user level buffer, supplied to {read,write}(file0),
2181 * is a part of a memory mapped lustre file, client has to take a dlm
2182 * locks on file0, and all files that back up the buffer (or a part of
2183 * the buffer, that is being processed in the current chunk, in any
2184 * case, there are situations where at least 2 locks are necessary).
2186 * In such cases we at least try to take locks in the same consistent
2187 * order. To this end, all locks are first collected, then sorted, and then
2191 /** locks to be acquired. */
2192 struct list_head cls_todo;
2193 /** locks currently being processed. */
2194 struct list_head cls_curr;
2195 /** locks acquired. */
2196 struct list_head cls_done;
2200 * Lock requirements(demand) for IO. It should be cl_io_lock_req,
2201 * but 'req' is always to be thought as 'request' :-)
2203 enum cl_io_lock_dmd {
2204 /** Always lock data (e.g., O_APPEND). */
2206 /** Layers are free to decide between local and global locking. */
2208 /** Never lock: there is no cache (e.g., liblustre). */
2212 struct cl_io_rw_common {
2221 * cl_io is shared by all threads participating in this IO (in current
2222 * implementation only one thread advances IO, but parallel IO design and
2223 * concurrent copy_*_user() require multiple threads acting on the same IO. It
2224 * is up to these threads to serialize their activities, including updates to
2225 * mutable cl_io fields.
2228 /** type of this IO. Immutable after creation. */
2229 enum cl_io_type ci_type;
2230 /** current state of cl_io state machine. */
2231 enum cl_io_state ci_state;
2232 /** main object this io is against. Immutable after creation. */
2233 struct cl_object *ci_obj;
2235 * Upper layer io, of which this io is a part of. Immutable after
2238 struct cl_io *ci_parent;
2239 /** List of slices. Immutable after creation. */
2240 struct list_head ci_layers;
2241 /** list of locks (to be) acquired by this io. */
2242 struct cl_lockset ci_lockset;
2243 /** lock requirements, this is just a help info for sublayers. */
2244 enum cl_io_lock_dmd ci_lockreq;
2246 * This io has held grouplock, to inform sublayers that
2247 * don't do lockless i/o.
2252 struct cl_io_rw_common rd;
2256 struct cl_io_rw_common wr;
2259 struct cl_io_rw_common ci_rw;
2260 struct cl_truncate_io {
2261 /** new size to which file is truncated */
2263 struct obd_capa *tr_capa;
2265 struct cl_fault_io {
2266 /** page index within file. */
2268 /** bytes valid byte on a faulted page. */
2270 /** writable page? */
2272 /** page of an executable? */
2274 /** resulting page */
2275 struct cl_page *ft_page;
2278 struct cl_2queue ci_queue;
2283 * Number of pages owned by this IO. For invariant checking.
2285 unsigned ci_owned_nr;
2290 /** \addtogroup cl_req cl_req
2295 * There are two possible modes of transfer initiation on the client:
2297 * - immediate transfer: this is started when a high level io wants a page
2298 * or a collection of pages to be transferred right away. Examples:
2299 * read-ahead, synchronous read in the case of non-page aligned write,
2300 * page write-out as a part of extent lock cancellation, page write-out
2301 * as a part of memory cleansing. Immediate transfer can be both
2302 * cl_req_type::CRT_READ and cl_req_type::CRT_WRITE;
2304 * - opportunistic transfer (cl_req_type::CRT_WRITE only), that happens
2305 * when io wants to transfer a page to the server some time later, when
2306 * it can be done efficiently. Example: pages dirtied by the write(2)
2309 * In any case, transfer takes place in the form of a cl_req, which is a
2310 * representation for a network RPC.
2312 * Pages queued for an opportunistic transfer are cached until it is decided
2313 * that efficient RPC can be composed of them. This decision is made by "a
2314 * req-formation engine", currently implemented as a part of osc
2315 * layer. Req-formation depends on many factors: the size of the resulting
2316 * RPC, whether or not multi-object RPCs are supported by the server,
2317 * max-rpc-in-flight limitations, size of the dirty cache, etc.
2319 * For the immediate transfer io submits a cl_page_list, that req-formation
2320 * engine slices into cl_req's, possibly adding cached pages to some of
2321 * the resulting req's.
2323 * Whenever a page from cl_page_list is added to a newly constructed req, its
2324 * cl_page_operations::cpo_prep() layer methods are called. At that moment,
2325 * page state is atomically changed from cl_page_state::CPS_OWNED to
2326 * cl_page_state::CPS_PAGEOUT or cl_page_state::CPS_PAGEIN, cl_page::cp_owner
2327 * is zeroed, and cl_page::cp_req is set to the
2328 * req. cl_page_operations::cpo_prep() method at the particular layer might
2329 * return -EALREADY to indicate that it does not need to submit this page
2330 * at all. This is possible, for example, if page, submitted for read,
2331 * became up-to-date in the meantime; and for write, the page don't have
2332 * dirty bit marked. \see cl_io_submit_rw()
2334 * Whenever a cached page is added to a newly constructed req, its
2335 * cl_page_operations::cpo_make_ready() layer methods are called. At that
2336 * moment, page state is atomically changed from cl_page_state::CPS_CACHED to
2337 * cl_page_state::CPS_PAGEOUT, and cl_page::cp_req is set to
2338 * req. cl_page_operations::cpo_make_ready() method at the particular layer
2339 * might return -EAGAIN to indicate that this page is not eligible for the
2340 * transfer right now.
2344 * Plan is to divide transfers into "priority bands" (indicated when
2345 * submitting cl_page_list, and queuing a page for the opportunistic transfer)
2346 * and allow glueing of cached pages to immediate transfers only within single
2347 * band. This would make high priority transfers (like lock cancellation or
2348 * memory pressure induced write-out) really high priority.
2353 * Per-transfer attributes.
2355 struct cl_req_attr {
2356 /** Generic attributes for the server consumption. */
2357 struct obdo *cra_oa;
2359 struct obd_capa *cra_capa;
2363 * Transfer request operations definable at every layer.
2365 * Concurrency: transfer formation engine synchronizes calls to all transfer
2368 struct cl_req_operations {
2370 * Invoked top-to-bottom by cl_req_prep() when transfer formation is
2371 * complete (all pages are added).
2373 * \see osc_req_prep()
2375 int (*cro_prep)(const struct lu_env *env,
2376 const struct cl_req_slice *slice);
2378 * Called top-to-bottom to fill in \a oa fields. This is called twice
2379 * with different flags, see bug 10150 and osc_build_req().
2381 * \param obj an object from cl_req which attributes are to be set in
2384 * \param oa struct obdo where attributes are placed
2386 * \param flags \a oa fields to be filled.
2388 void (*cro_attr_set)(const struct lu_env *env,
2389 const struct cl_req_slice *slice,
2390 const struct cl_object *obj,
2391 struct cl_req_attr *attr, obd_valid flags);
2393 * Called top-to-bottom from cl_req_completion() to notify layers that
2394 * transfer completed. Has to free all state allocated by
2395 * cl_device_operations::cdo_req_init().
2397 void (*cro_completion)(const struct lu_env *env,
2398 const struct cl_req_slice *slice, int ioret);
2402 * A per-object state that (potentially multi-object) transfer request keeps.
2405 /** object itself */
2406 struct cl_object *ro_obj;
2407 /** reference to cl_req_obj::ro_obj. For debugging. */
2408 struct lu_ref_link *ro_obj_ref;
2409 /* something else? Number of pages for a given object? */
2415 * Transfer requests are not reference counted, because IO sub-system owns
2416 * them exclusively and knows when to free them.
2420 * cl_req is created by cl_req_alloc() that calls
2421 * cl_device_operations::cdo_req_init() device methods to allocate per-req
2422 * state in every layer.
2424 * Then pages are added (cl_req_page_add()), req keeps track of all objects it
2425 * contains pages for.
2427 * Once all pages were collected, cl_page_operations::cpo_prep() method is
2428 * called top-to-bottom. At that point layers can modify req, let it pass, or
2429 * deny it completely. This is to support things like SNS that have transfer
2430 * ordering requirements invisible to the individual req-formation engine.
2432 * On transfer completion (or transfer timeout, or failure to initiate the
2433 * transfer of an allocated req), cl_req_operations::cro_completion() method
2434 * is called, after execution of cl_page_operations::cpo_completion() of all
2438 enum cl_req_type crq_type;
2439 /** A list of pages being transfered */
2440 struct list_head crq_pages;
2441 /** Number of pages in cl_req::crq_pages */
2442 unsigned crq_nrpages;
2443 /** An array of objects which pages are in ->crq_pages */
2444 struct cl_req_obj *crq_o;
2445 /** Number of elements in cl_req::crq_objs[] */
2446 unsigned crq_nrobjs;
2447 struct list_head crq_layers;
2451 * Per-layer state for request.
2453 struct cl_req_slice {
2454 struct cl_req *crs_req;
2455 struct cl_device *crs_dev;
2456 struct list_head crs_linkage;
2457 const struct cl_req_operations *crs_ops;
2463 * Stats for a generic cache (similar to inode, lu_object, etc. caches).
2465 struct cache_stats {
2466 const char *cs_name;
2467 /** how many entities were created at all */
2468 atomic_t cs_created;
2469 /** how many cache lookups were performed */
2471 /** how many times cache lookup resulted in a hit */
2473 /** how many entities are in the cache right now */
2475 /** how many entities in the cache are actively used (and cannot be
2476 * evicted) right now */
2480 /** These are not exported so far */
2481 void cache_stats_init (struct cache_stats *cs, const char *name);
2482 int cache_stats_print(const struct cache_stats *cs,
2483 char *page, int count, int header);
2486 * Client-side site. This represents particular client stack. "Global"
2487 * variables should (directly or indirectly) be added here to allow multiple
2488 * clients to co-exist in the single address space.
2491 struct lu_site cs_lu;
2493 * Statistical counters. Atomics do not scale, something better like
2494 * per-cpu counters is needed.
2496 * These are exported as /proc/fs/lustre/llite/.../site
2498 * When interpreting keep in mind that both sub-locks (and sub-pages)
2499 * and top-locks (and top-pages) are accounted here.
2501 struct cache_stats cs_pages;
2502 struct cache_stats cs_locks;
2503 atomic_t cs_pages_state[CPS_NR];
2504 atomic_t cs_locks_state[CLS_NR];
2507 int cl_site_init (struct cl_site *s, struct cl_device *top);
2508 void cl_site_fini (struct cl_site *s);
2509 void cl_stack_fini(const struct lu_env *env, struct cl_device *cl);
2512 * Output client site statistical counters into a buffer. Suitable for
2513 * ll_rd_*()-style functions.
2515 int cl_site_stats_print(const struct cl_site *s, char *page, int count);
2520 * Type conversion and accessory functions.
2524 static inline struct cl_site *lu2cl_site(const struct lu_site *site)
2526 return container_of(site, struct cl_site, cs_lu);
2529 static inline int lu_device_is_cl(const struct lu_device *d)
2531 return d->ld_type->ldt_tags & LU_DEVICE_CL;
2534 static inline struct cl_device *lu2cl_dev(const struct lu_device *d)
2536 LASSERT(d == NULL || IS_ERR(d) || lu_device_is_cl(d));
2537 return container_of0(d, struct cl_device, cd_lu_dev);
2540 static inline struct lu_device *cl2lu_dev(struct cl_device *d)
2542 return &d->cd_lu_dev;
2545 static inline struct cl_object *lu2cl(const struct lu_object *o)
2547 LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->lo_dev));
2548 return container_of0(o, struct cl_object, co_lu);
2551 static inline const struct cl_object_conf *
2552 lu2cl_conf(const struct lu_object_conf *conf)
2554 return container_of0(conf, struct cl_object_conf, coc_lu);
2557 static inline struct cl_object *cl_object_next(const struct cl_object *obj)
2559 return obj ? lu2cl(lu_object_next(&obj->co_lu)) : NULL;
2562 static inline struct cl_device *cl_object_device(const struct cl_object *o)
2564 LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->co_lu.lo_dev));
2565 return container_of0(o->co_lu.lo_dev, struct cl_device, cd_lu_dev);
2568 static inline struct cl_object_header *luh2coh(const struct lu_object_header *h)
2570 return container_of0(h, struct cl_object_header, coh_lu);
2573 static inline struct cl_site *cl_object_site(const struct cl_object *obj)
2575 return lu2cl_site(obj->co_lu.lo_dev->ld_site);
2579 struct cl_object_header *cl_object_header(const struct cl_object *obj)
2581 return luh2coh(obj->co_lu.lo_header);
2584 static inline int cl_device_init(struct cl_device *d, struct lu_device_type *t)
2586 return lu_device_init(&d->cd_lu_dev, t);
2589 static inline void cl_device_fini(struct cl_device *d)
2591 lu_device_fini(&d->cd_lu_dev);
2594 void cl_page_slice_add(struct cl_page *page, struct cl_page_slice *slice,
2595 struct cl_object *obj,
2596 const struct cl_page_operations *ops);
2597 void cl_lock_slice_add(struct cl_lock *lock, struct cl_lock_slice *slice,
2598 struct cl_object *obj,
2599 const struct cl_lock_operations *ops);
2600 void cl_io_slice_add(struct cl_io *io, struct cl_io_slice *slice,
2601 struct cl_object *obj, const struct cl_io_operations *ops);
2602 void cl_req_slice_add(struct cl_req *req, struct cl_req_slice *slice,
2603 struct cl_device *dev,
2604 const struct cl_req_operations *ops);
2607 /** \defgroup cl_object cl_object
2609 struct cl_object *cl_object_top (struct cl_object *o);
2610 struct cl_object *cl_object_find(const struct lu_env *env, struct cl_device *cd,
2611 const struct lu_fid *fid,
2612 const struct cl_object_conf *c);
2614 int cl_object_header_init(struct cl_object_header *h);
2615 void cl_object_header_fini(struct cl_object_header *h);
2616 void cl_object_put (const struct lu_env *env, struct cl_object *o);
2617 void cl_object_get (struct cl_object *o);
2618 void cl_object_attr_lock (struct cl_object *o);
2619 void cl_object_attr_unlock(struct cl_object *o);
2620 int cl_object_attr_get (const struct lu_env *env, struct cl_object *obj,
2621 struct cl_attr *attr);
2622 int cl_object_attr_set (const struct lu_env *env, struct cl_object *obj,
2623 const struct cl_attr *attr, unsigned valid);
2624 int cl_object_glimpse (const struct lu_env *env, struct cl_object *obj,
2625 struct ost_lvb *lvb);
2626 int cl_conf_set (const struct lu_env *env, struct cl_object *obj,
2627 const struct cl_object_conf *conf);
2628 void cl_object_prune (const struct lu_env *env, struct cl_object *obj);
2629 void cl_object_kill (const struct lu_env *env, struct cl_object *obj);
2632 * Returns true, iff \a o0 and \a o1 are slices of the same object.
2634 static inline int cl_object_same(struct cl_object *o0, struct cl_object *o1)
2636 return cl_object_header(o0) == cl_object_header(o1);
2641 /** \defgroup cl_page cl_page
2643 struct cl_page *cl_page_lookup(struct cl_object_header *hdr,
2645 void cl_page_gang_lookup(const struct lu_env *env,
2646 struct cl_object *obj,
2648 pgoff_t start, pgoff_t end,
2649 struct cl_page_list *plist);
2650 struct cl_page *cl_page_find (const struct lu_env *env,
2651 struct cl_object *obj,
2652 pgoff_t idx, struct page *vmpage,
2653 enum cl_page_type type);
2654 void cl_page_get (struct cl_page *page);
2655 void cl_page_put (const struct lu_env *env,
2656 struct cl_page *page);
2657 void cl_page_print (const struct lu_env *env, void *cookie,
2658 lu_printer_t printer,
2659 const struct cl_page *pg);
2660 void cl_page_header_print(const struct lu_env *env, void *cookie,
2661 lu_printer_t printer,
2662 const struct cl_page *pg);
2663 cfs_page_t *cl_page_vmpage (const struct lu_env *env,
2664 struct cl_page *page);
2665 struct cl_page *cl_vmpage_page (cfs_page_t *vmpage, struct cl_object *obj);
2666 struct cl_page *cl_page_top (struct cl_page *page);
2667 int cl_is_page (const void *addr);
2669 const struct cl_page_slice *cl_page_at(const struct cl_page *page,
2670 const struct lu_device_type *dtype);
2675 * Functions dealing with the ownership of page by io.
2679 int cl_page_own (const struct lu_env *env,
2680 struct cl_io *io, struct cl_page *page);
2681 void cl_page_assume (const struct lu_env *env,
2682 struct cl_io *io, struct cl_page *page);
2683 void cl_page_unassume (const struct lu_env *env,
2684 struct cl_io *io, struct cl_page *pg);
2685 void cl_page_disown (const struct lu_env *env,
2686 struct cl_io *io, struct cl_page *page);
2687 int cl_page_is_owned (const struct cl_page *pg, const struct cl_io *io);
2694 * Functions dealing with the preparation of a page for a transfer, and
2695 * tracking transfer state.
2698 int cl_page_prep (const struct lu_env *env, struct cl_io *io,
2699 struct cl_page *pg, enum cl_req_type crt);
2700 void cl_page_completion (const struct lu_env *env,
2701 struct cl_page *pg, enum cl_req_type crt, int ioret);
2702 int cl_page_make_ready (const struct lu_env *env, struct cl_page *pg,
2703 enum cl_req_type crt);
2704 int cl_page_cache_add (const struct lu_env *env, struct cl_io *io,
2705 struct cl_page *pg, enum cl_req_type crt);
2706 void cl_page_clip (const struct lu_env *env, struct cl_page *pg,
2708 int cl_page_cancel (const struct lu_env *env, struct cl_page *page);
2714 * \name helper routines
2715 * Functions to discard, delete and export a cl_page.
2718 void cl_page_discard (const struct lu_env *env, struct cl_io *io,
2719 struct cl_page *pg);
2720 void cl_page_delete (const struct lu_env *env, struct cl_page *pg);
2721 int cl_page_unmap (const struct lu_env *env, struct cl_io *io,
2722 struct cl_page *pg);
2723 int cl_page_is_vmlocked (const struct lu_env *env,
2724 const struct cl_page *pg);
2725 void cl_page_export (const struct lu_env *env,
2726 struct cl_page *pg, int uptodate);
2727 int cl_page_is_under_lock(const struct lu_env *env, struct cl_io *io,
2728 struct cl_page *page);
2729 loff_t cl_offset (const struct cl_object *obj, pgoff_t idx);
2730 pgoff_t cl_index (const struct cl_object *obj, loff_t offset);
2731 int cl_page_size (const struct cl_object *obj);
2732 int cl_pages_prune (const struct lu_env *env, struct cl_object *obj);
2734 void cl_lock_print (const struct lu_env *env, void *cookie,
2735 lu_printer_t printer, const struct cl_lock *lock);
2736 void cl_lock_descr_print(const struct lu_env *env, void *cookie,
2737 lu_printer_t printer,
2738 const struct cl_lock_descr *descr);
2743 /** \defgroup cl_lock cl_lock
2746 struct cl_lock *cl_lock_hold(const struct lu_env *env, const struct cl_io *io,
2747 const struct cl_lock_descr *need,
2748 const char *scope, const void *source);
2749 struct cl_lock *cl_lock_peek(const struct lu_env *env, const struct cl_io *io,
2750 const struct cl_lock_descr *need,
2751 const char *scope, const void *source);
2752 struct cl_lock *cl_lock_request(const struct lu_env *env, struct cl_io *io,
2753 const struct cl_lock_descr *need,
2755 const char *scope, const void *source);
2756 struct cl_lock *cl_lock_at_page(const struct lu_env *env, struct cl_object *obj,
2757 struct cl_page *page, struct cl_lock *except,
2758 int pending, int canceld);
2760 const struct cl_lock_slice *cl_lock_at(const struct cl_lock *lock,
2761 const struct lu_device_type *dtype);
2763 void cl_lock_get (struct cl_lock *lock);
2764 void cl_lock_get_trust (struct cl_lock *lock);
2765 void cl_lock_put (const struct lu_env *env, struct cl_lock *lock);
2766 void cl_lock_hold_add (const struct lu_env *env, struct cl_lock *lock,
2767 const char *scope, const void *source);
2768 void cl_lock_unhold (const struct lu_env *env, struct cl_lock *lock,
2769 const char *scope, const void *source);
2770 void cl_lock_release (const struct lu_env *env, struct cl_lock *lock,
2771 const char *scope, const void *source);
2772 void cl_lock_user_add (const struct lu_env *env, struct cl_lock *lock);
2773 int cl_lock_user_del (const struct lu_env *env, struct cl_lock *lock);
2774 int cl_lock_compatible(const struct cl_lock *lock1,
2775 const struct cl_lock *lock2);
2777 /** \name statemachine statemachine
2778 * Interface to lock state machine consists of 3 parts:
2780 * - "try" functions that attempt to effect a state transition. If state
2781 * transition is not possible right now (e.g., if it has to wait for some
2782 * asynchronous event to occur), these functions return
2783 * cl_lock_transition::CLO_WAIT.
2785 * - "non-try" functions that implement synchronous blocking interface on
2786 * top of non-blocking "try" functions. These functions repeatedly call
2787 * corresponding "try" versions, and if state transition is not possible
2788 * immediately, wait for lock state change.
2790 * - methods from cl_lock_operations, called by "try" functions. Lock can
2791 * be advanced to the target state only when all layers voted that they
2792 * are ready for this transition. "Try" functions call methods under lock
2793 * mutex. If a layer had to release a mutex, it re-acquires it and returns
2794 * cl_lock_transition::CLO_REPEAT, causing "try" function to call all
2797 * TRY NON-TRY METHOD FINAL STATE
2799 * cl_enqueue_try() cl_enqueue() cl_lock_operations::clo_enqueue() CLS_ENQUEUED
2801 * cl_wait_try() cl_wait() cl_lock_operations::clo_wait() CLS_HELD
2803 * cl_unuse_try() cl_unuse() cl_lock_operations::clo_unuse() CLS_CACHED
2805 * cl_use_try() NONE cl_lock_operations::clo_use() CLS_HELD
2809 int cl_enqueue (const struct lu_env *env, struct cl_lock *lock,
2810 struct cl_io *io, __u32 flags);
2811 int cl_wait (const struct lu_env *env, struct cl_lock *lock);
2812 void cl_unuse (const struct lu_env *env, struct cl_lock *lock);
2813 int cl_enqueue_try(const struct lu_env *env, struct cl_lock *lock,
2814 struct cl_io *io, __u32 flags);
2815 int cl_unuse_try (const struct lu_env *env, struct cl_lock *lock);
2816 int cl_wait_try (const struct lu_env *env, struct cl_lock *lock);
2817 int cl_use_try (const struct lu_env *env, struct cl_lock *lock);
2818 /** @} statemachine */
2820 void cl_lock_signal (const struct lu_env *env, struct cl_lock *lock);
2821 int cl_lock_state_wait (const struct lu_env *env, struct cl_lock *lock);
2822 void cl_lock_state_set (const struct lu_env *env, struct cl_lock *lock,
2823 enum cl_lock_state state);
2824 int cl_queue_match (const struct list_head *queue,
2825 const struct cl_lock_descr *need);
2827 void cl_lock_mutex_get (const struct lu_env *env, struct cl_lock *lock);
2828 int cl_lock_mutex_try (const struct lu_env *env, struct cl_lock *lock);
2829 void cl_lock_mutex_put (const struct lu_env *env, struct cl_lock *lock);
2830 int cl_lock_is_mutexed (struct cl_lock *lock);
2831 int cl_lock_nr_mutexed (const struct lu_env *env);
2832 int cl_lock_page_out (const struct lu_env *env, struct cl_lock *lock,
2834 int cl_lock_ext_match (const struct cl_lock_descr *has,
2835 const struct cl_lock_descr *need);
2836 int cl_lock_descr_match(const struct cl_lock_descr *has,
2837 const struct cl_lock_descr *need);
2838 int cl_lock_mode_match (enum cl_lock_mode has, enum cl_lock_mode need);
2839 int cl_lock_modify (const struct lu_env *env, struct cl_lock *lock,
2840 const struct cl_lock_descr *desc);
2842 void cl_lock_closure_init (const struct lu_env *env,
2843 struct cl_lock_closure *closure,
2844 struct cl_lock *origin, int wait);
2845 void cl_lock_closure_fini (struct cl_lock_closure *closure);
2846 int cl_lock_closure_build(const struct lu_env *env, struct cl_lock *lock,
2847 struct cl_lock_closure *closure);
2848 void cl_lock_disclosure (const struct lu_env *env,
2849 struct cl_lock_closure *closure);
2850 int cl_lock_enclosure (const struct lu_env *env, struct cl_lock *lock,
2851 struct cl_lock_closure *closure);
2853 void cl_lock_cancel(const struct lu_env *env, struct cl_lock *lock);
2854 void cl_lock_delete(const struct lu_env *env, struct cl_lock *lock);
2855 void cl_lock_error (const struct lu_env *env, struct cl_lock *lock, int error);
2856 void cl_locks_prune(const struct lu_env *env, struct cl_object *obj, int wait);
2857 int cl_is_lock (const void *addr);
2859 unsigned long cl_lock_weigh(const struct lu_env *env, struct cl_lock *lock);
2863 /** \defgroup cl_io cl_io
2866 int cl_io_init (const struct lu_env *env, struct cl_io *io,
2867 enum cl_io_type iot, struct cl_object *obj);
2868 int cl_io_sub_init (const struct lu_env *env, struct cl_io *io,
2869 enum cl_io_type iot, struct cl_object *obj);
2870 int cl_io_rw_init (const struct lu_env *env, struct cl_io *io,
2871 enum cl_io_type iot, loff_t pos, size_t count);
2872 int cl_io_loop (const struct lu_env *env, struct cl_io *io);
2874 void cl_io_fini (const struct lu_env *env, struct cl_io *io);
2875 int cl_io_iter_init (const struct lu_env *env, struct cl_io *io);
2876 void cl_io_iter_fini (const struct lu_env *env, struct cl_io *io);
2877 int cl_io_lock (const struct lu_env *env, struct cl_io *io);
2878 void cl_io_unlock (const struct lu_env *env, struct cl_io *io);
2879 int cl_io_start (const struct lu_env *env, struct cl_io *io);
2880 void cl_io_end (const struct lu_env *env, struct cl_io *io);
2881 int cl_io_lock_add (const struct lu_env *env, struct cl_io *io,
2882 struct cl_io_lock_link *link);
2883 int cl_io_lock_alloc_add(const struct lu_env *env, struct cl_io *io,
2884 struct cl_lock_descr *descr, int enqflags);
2885 int cl_io_read_page (const struct lu_env *env, struct cl_io *io,
2886 struct cl_page *page);
2887 int cl_io_prepare_write(const struct lu_env *env, struct cl_io *io,
2888 struct cl_page *page, unsigned from, unsigned to);
2889 int cl_io_commit_write (const struct lu_env *env, struct cl_io *io,
2890 struct cl_page *page, unsigned from, unsigned to);
2891 int cl_io_submit_rw (const struct lu_env *env, struct cl_io *io,
2892 enum cl_req_type iot, struct cl_2queue *queue,
2893 enum cl_req_priority priority);
2894 int cl_io_submit_sync (const struct lu_env *env, struct cl_io *io,
2895 enum cl_req_type iot, struct cl_2queue *queue,
2896 enum cl_req_priority priority, long timeout);
2897 void cl_io_rw_advance (const struct lu_env *env, struct cl_io *io,
2899 int cl_io_cancel (const struct lu_env *env, struct cl_io *io,
2900 struct cl_page_list *queue);
2901 int cl_io_is_going (const struct lu_env *env);
2904 * True, iff \a io is an O_APPEND write(2).
2906 static inline int cl_io_is_append(const struct cl_io *io)
2908 return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_append;
2911 int cl_io_is_sendfile(const struct cl_io *io);
2913 struct cl_io *cl_io_top(struct cl_io *io);
2915 void cl_io_print(const struct lu_env *env, void *cookie,
2916 lu_printer_t printer, const struct cl_io *io);
2918 #define CL_IO_SLICE_CLEAN(foo_io, base) \
2920 typeof(foo_io) __foo_io = (foo_io); \
2922 CLASSERT(offsetof(typeof(*__foo_io), base) == 0); \
2923 memset(&__foo_io->base + 1, 0, \
2924 (sizeof *__foo_io) - sizeof __foo_io->base); \
2929 /** \defgroup cl_page_list cl_page_list
2933 * Iterate over pages in a page list.
2935 #define cl_page_list_for_each(page, list) \
2936 list_for_each_entry((page), &(list)->pl_pages, cp_batch)
2939 * Iterate over pages in a page list, taking possible removals into account.
2941 #define cl_page_list_for_each_safe(page, temp, list) \
2942 list_for_each_entry_safe((page), (temp), &(list)->pl_pages, cp_batch)
2944 void cl_page_list_init (struct cl_page_list *plist);
2945 void cl_page_list_add (struct cl_page_list *plist, struct cl_page *page);
2946 void cl_page_list_move (struct cl_page_list *dst, struct cl_page_list *src,
2947 struct cl_page *page);
2948 void cl_page_list_splice (struct cl_page_list *list,
2949 struct cl_page_list *head);
2950 void cl_page_list_del (const struct lu_env *env,
2951 struct cl_page_list *plist, struct cl_page *page);
2952 void cl_page_list_disown (const struct lu_env *env,
2953 struct cl_io *io, struct cl_page_list *plist);
2954 int cl_page_list_own (const struct lu_env *env,
2955 struct cl_io *io, struct cl_page_list *plist);
2956 void cl_page_list_assume (const struct lu_env *env,
2957 struct cl_io *io, struct cl_page_list *plist);
2958 void cl_page_list_discard(const struct lu_env *env,
2959 struct cl_io *io, struct cl_page_list *plist);
2960 int cl_page_list_unmap (const struct lu_env *env,
2961 struct cl_io *io, struct cl_page_list *plist);
2962 void cl_page_list_fini (const struct lu_env *env, struct cl_page_list *plist);
2964 void cl_2queue_init (struct cl_2queue *queue);
2965 void cl_2queue_add (struct cl_2queue *queue, struct cl_page *page);
2966 void cl_2queue_disown (const struct lu_env *env,
2967 struct cl_io *io, struct cl_2queue *queue);
2968 void cl_2queue_assume (const struct lu_env *env,
2969 struct cl_io *io, struct cl_2queue *queue);
2970 void cl_2queue_discard (const struct lu_env *env,
2971 struct cl_io *io, struct cl_2queue *queue);
2972 void cl_2queue_fini (const struct lu_env *env, struct cl_2queue *queue);
2973 void cl_2queue_init_page(struct cl_2queue *queue, struct cl_page *page);
2975 /** @} cl_page_list */
2977 /** \defgroup cl_req cl_req
2979 struct cl_req *cl_req_alloc(const struct lu_env *env, struct cl_page *page,
2980 enum cl_req_type crt, int nr_objects);
2982 void cl_req_page_add (const struct lu_env *env, struct cl_req *req,
2983 struct cl_page *page);
2984 void cl_req_page_done (const struct lu_env *env, struct cl_page *page);
2985 int cl_req_prep (const struct lu_env *env, struct cl_req *req);
2986 void cl_req_attr_set (const struct lu_env *env, struct cl_req *req,
2987 struct cl_req_attr *attr, obd_valid flags);
2988 void cl_req_completion(const struct lu_env *env, struct cl_req *req, int ioret);
2990 /** \defgroup cl_sync_io cl_sync_io
2994 * Anchor for synchronous transfer. This is allocated on a stack by thread
2995 * doing synchronous transfer, and a pointer to this structure is set up in
2996 * every page submitted for transfer. Transfer completion routine updates
2997 * anchor and wakes up waiting thread when transfer is complete.
3000 /** number of pages yet to be transferred. */
3001 atomic_t csi_sync_nr;
3002 /** completion to be signaled when transfer is complete. */
3003 cfs_waitq_t csi_waitq;
3008 void cl_sync_io_init(struct cl_sync_io *anchor, int nrpages);
3009 int cl_sync_io_wait(const struct lu_env *env, struct cl_io *io,
3010 struct cl_page_list *queue, struct cl_sync_io *anchor,
3012 void cl_sync_io_note(struct cl_sync_io *anchor, int ioret);
3014 /** @} cl_sync_io */
3018 /** \defgroup cl_env cl_env
3020 * lu_env handling for a client.
3022 * lu_env is an environment within which lustre code executes. Its major part
3023 * is lu_context---a fast memory allocation mechanism that is used to conserve
3024 * precious kernel stack space. Originally lu_env was designed for a server,
3027 * - there is a (mostly) fixed number of threads, and
3029 * - call chains have no non-lustre portions inserted between lustre code.
3031 * On a client both these assumtpion fails, because every user thread can
3032 * potentially execute lustre code as part of a system call, and lustre calls
3033 * into VFS or MM that call back into lustre.
3035 * To deal with that, cl_env wrapper functions implement the following
3038 * - allocation and destruction of environment is amortized by caching no
3039 * longer used environments instead of destroying them;
3041 * - there is a notion of "current" environment, attached to the kernel
3042 * data structure representing current thread (current->journal_info in
3043 * Linux kernel). Top-level lustre code allocates an environment and makes
3044 * it current, then calls into non-lustre code, that in turn calls lustre
3045 * back. Low-level lustre code thus called can fetch environment created
3046 * by the top-level code and reuse it, avoiding additional environment
3049 * \see lu_env, lu_context, lu_context_key
3052 struct cl_env_nest {
3057 struct lu_env *cl_env_peek (int *refcheck);
3058 struct lu_env *cl_env_get (int *refcheck);
3059 struct lu_env *cl_env_alloc (int *refcheck, __u32 tags);
3060 struct lu_env *cl_env_nested_get (struct cl_env_nest *nest);
3061 void cl_env_put (struct lu_env *env, int *refcheck);
3062 void cl_env_nested_put (struct cl_env_nest *nest, struct lu_env *env);
3063 void *cl_env_reenter (void);
3064 void cl_env_reexit (void *cookie);
3065 void cl_env_implant (struct lu_env *env, int *refcheck);
3066 void cl_env_unplant (struct lu_env *env, int *refcheck);
3067 unsigned cl_env_cache_purge(unsigned nr);
3074 void cl_attr2lvb(struct ost_lvb *lvb, const struct cl_attr *attr);
3075 void cl_lvb2attr(struct cl_attr *attr, const struct ost_lvb *lvb);
3077 struct cl_device *cl_type_setup(const struct lu_env *env, struct lu_site *site,
3078 struct lu_device_type *ldt,
3079 struct lu_device *next);
3082 #endif /* _LINUX_CL_OBJECT_H */