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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
87 * See the top comment in cl_object.c for the description of overall locking and
88 * reference-counting design.
90 * See comments below for the description of i/o, page, and dlm-locking
97 * super-class definitions.
99 #include <libcfs/libcfs.h>
100 #include <lu_object.h>
101 #include <linux/atomic.h>
102 #include <linux/mutex.h>
103 #include <linux/radix-tree.h>
104 #include <linux/spinlock.h>
105 #include <linux/wait.h>
106 #include <lustre_dlm.h>
111 struct cl_device_operations;
114 struct cl_object_page_operations;
115 struct cl_object_lock_operations;
118 struct cl_page_slice;
120 struct cl_lock_slice;
122 struct cl_lock_operations;
123 struct cl_page_operations;
132 * Operations for each data device in the client stack.
134 * \see vvp_cl_ops, lov_cl_ops, lovsub_cl_ops, osc_cl_ops
136 struct cl_device_operations {
138 * Initialize cl_req. This method is called top-to-bottom on all
139 * devices in the stack to get them a chance to allocate layer-private
140 * data, and to attach them to the cl_req by calling
141 * cl_req_slice_add().
143 * \see osc_req_init(), lov_req_init(), lovsub_req_init()
144 * \see vvp_req_init()
146 int (*cdo_req_init)(const struct lu_env *env, struct cl_device *dev,
151 * Device in the client stack.
153 * \see vvp_device, lov_device, lovsub_device, osc_device
157 struct lu_device cd_lu_dev;
158 /** Per-layer operation vector. */
159 const struct cl_device_operations *cd_ops;
162 /** \addtogroup cl_object cl_object
165 * "Data attributes" of cl_object. Data attributes can be updated
166 * independently for a sub-object, and top-object's attributes are calculated
167 * from sub-objects' ones.
170 /** Object size, in bytes */
173 * Known minimal size, in bytes.
175 * This is only valid when at least one DLM lock is held.
178 /** Modification time. Measured in seconds since epoch. */
180 /** Access time. Measured in seconds since epoch. */
182 /** Change time. Measured in seconds since epoch. */
185 * Blocks allocated to this cl_object on the server file system.
187 * \todo XXX An interface for block size is needed.
191 * User identifier for quota purposes.
195 * Group identifier for quota purposes.
199 /* nlink of the directory */
204 * Fields in cl_attr that are being set.
218 * Sub-class of lu_object with methods common for objects on the client
221 * cl_object: represents a regular file system object, both a file and a
222 * stripe. cl_object is based on lu_object: it is identified by a fid,
223 * layered, cached, hashed, and lrued. Important distinction with the server
224 * side, where md_object and dt_object are used, is that cl_object "fans out"
225 * at the lov/sns level: depending on the file layout, single file is
226 * represented as a set of "sub-objects" (stripes). At the implementation
227 * level, struct lov_object contains an array of cl_objects. Each sub-object
228 * is a full-fledged cl_object, having its fid, living in the lru and hash
231 * This leads to the next important difference with the server side: on the
232 * client, it's quite usual to have objects with the different sequence of
233 * layers. For example, typical top-object is composed of the following
239 * whereas its sub-objects are composed of
244 * layers. Here "lovsub" is a mostly dummy layer, whose purpose is to keep
245 * track of the object-subobject relationship.
247 * Sub-objects are not cached independently: when top-object is about to
248 * be discarded from the memory, all its sub-objects are torn-down and
251 * \see vvp_object, lov_object, lovsub_object, osc_object
255 struct lu_object co_lu;
256 /** per-object-layer operations */
257 const struct cl_object_operations *co_ops;
258 /** offset of page slice in cl_page buffer */
263 * Description of the client object configuration. This is used for the
264 * creation of a new client object that is identified by a more state than
267 struct cl_object_conf {
269 struct lu_object_conf coc_lu;
272 * Object layout. This is consumed by lov.
274 struct lustre_md *coc_md;
276 * Description of particular stripe location in the
277 * cluster. This is consumed by osc.
279 struct lov_oinfo *coc_oinfo;
282 * VFS inode. This is consumed by vvp.
284 struct inode *coc_inode;
286 * Layout lock handle.
288 struct ldlm_lock *coc_lock;
290 * Operation to handle layout, OBJECT_CONF_XYZ.
296 /** configure layout, set up a new stripe, must be called while
297 * holding layout lock. */
299 /** invalidate the current stripe configuration due to losing
301 OBJECT_CONF_INVALIDATE = 1,
302 /** wait for old layout to go away so that new layout can be
308 * Operations implemented for each cl object layer.
310 * \see vvp_ops, lov_ops, lovsub_ops, osc_ops
312 struct cl_object_operations {
314 * Initialize page slice for this layer. Called top-to-bottom through
315 * every object layer when a new cl_page is instantiated. Layer
316 * keeping private per-page data, or requiring its own page operations
317 * vector should allocate these data here, and attach then to the page
318 * by calling cl_page_slice_add(). \a vmpage is locked (in the VM
321 * \retval NULL success.
323 * \retval ERR_PTR(errno) failure code.
325 * \retval valid-pointer pointer to already existing referenced page
326 * to be used instead of newly created.
328 int (*coo_page_init)(const struct lu_env *env, struct cl_object *obj,
329 struct cl_page *page, pgoff_t index);
331 * Initialize lock slice for this layer. Called top-to-bottom through
332 * every object layer when a new cl_lock is instantiated. Layer
333 * keeping private per-lock data, or requiring its own lock operations
334 * vector should allocate these data here, and attach then to the lock
335 * by calling cl_lock_slice_add(). Mandatory.
337 int (*coo_lock_init)(const struct lu_env *env,
338 struct cl_object *obj, struct cl_lock *lock,
339 const struct cl_io *io);
341 * Initialize io state for a given layer.
343 * called top-to-bottom once per io existence to initialize io
344 * state. If layer wants to keep some state for this type of io, it
345 * has to embed struct cl_io_slice in lu_env::le_ses, and register
346 * slice with cl_io_slice_add(). It is guaranteed that all threads
347 * participating in this io share the same session.
349 int (*coo_io_init)(const struct lu_env *env,
350 struct cl_object *obj, struct cl_io *io);
352 * Fill portion of \a attr that this layer controls. This method is
353 * called top-to-bottom through all object layers.
355 * \pre cl_object_header::coh_attr_guard of the top-object is locked.
357 * \return 0: to continue
358 * \return +ve: to stop iterating through layers (but 0 is returned
359 * from enclosing cl_object_attr_get())
360 * \return -ve: to signal error
362 int (*coo_attr_get)(const struct lu_env *env, struct cl_object *obj,
363 struct cl_attr *attr);
367 * \a valid is a bitmask composed from enum #cl_attr_valid, and
368 * indicating what attributes are to be set.
370 * \pre cl_object_header::coh_attr_guard of the top-object is locked.
372 * \return the same convention as for
373 * cl_object_operations::coo_attr_get() is used.
375 int (*coo_attr_update)(const struct lu_env *env, struct cl_object *obj,
376 const struct cl_attr *attr, unsigned valid);
378 * Update object configuration. Called top-to-bottom to modify object
381 * XXX error conditions and handling.
383 int (*coo_conf_set)(const struct lu_env *env, struct cl_object *obj,
384 const struct cl_object_conf *conf);
386 * Glimpse ast. Executed when glimpse ast arrives for a lock on this
387 * object. Layers are supposed to fill parts of \a lvb that will be
388 * shipped to the glimpse originator as a glimpse result.
390 * \see vvp_object_glimpse(), lovsub_object_glimpse(),
391 * \see osc_object_glimpse()
393 int (*coo_glimpse)(const struct lu_env *env,
394 const struct cl_object *obj, struct ost_lvb *lvb);
396 * Object prune method. Called when the layout is going to change on
397 * this object, therefore each layer has to clean up their cache,
398 * mainly pages and locks.
400 int (*coo_prune)(const struct lu_env *env, struct cl_object *obj);
402 * Object getstripe method.
404 int (*coo_getstripe)(const struct lu_env *env, struct cl_object *obj,
405 struct lov_user_md __user *lum);
407 * Find whether there is any callback data (ldlm lock) attached upon
410 int (*coo_find_cbdata)(const struct lu_env *env, struct cl_object *obj,
411 ldlm_iterator_t iter, void *data);
415 * Extended header for client object.
417 struct cl_object_header {
418 /** Standard lu_object_header. cl_object::co_lu::lo_header points
420 struct lu_object_header coh_lu;
423 * Parent object. It is assumed that an object has a well-defined
424 * parent, but not a well-defined child (there may be multiple
425 * sub-objects, for the same top-object). cl_object_header::coh_parent
426 * field allows certain code to be written generically, without
427 * limiting possible cl_object layouts unduly.
429 struct cl_object_header *coh_parent;
431 * Protects consistency between cl_attr of parent object and
432 * attributes of sub-objects, that the former is calculated ("merged")
435 * \todo XXX this can be read/write lock if needed.
437 spinlock_t coh_attr_guard;
439 * Size of cl_page + page slices
441 unsigned short coh_page_bufsize;
443 * Number of objects above this one: 0 for a top-object, 1 for its
446 unsigned char coh_nesting;
450 * Helper macro: iterate over all layers of the object \a obj, assigning every
451 * layer top-to-bottom to \a slice.
453 #define cl_object_for_each(slice, obj) \
454 list_for_each_entry((slice), \
455 &(obj)->co_lu.lo_header->loh_layers,\
459 * Helper macro: iterate over all layers of the object \a obj, assigning every
460 * layer bottom-to-top to \a slice.
462 #define cl_object_for_each_reverse(slice, obj) \
463 list_for_each_entry_reverse((slice), \
464 &(obj)->co_lu.lo_header->loh_layers,\
469 #define CL_PAGE_EOF ((pgoff_t)~0ull)
471 /** \addtogroup cl_page cl_page
475 * Layered client page.
477 * cl_page: represents a portion of a file, cached in the memory. All pages
478 * of the given file are of the same size, and are kept in the radix tree
479 * hanging off the cl_object. cl_page doesn't fan out, but as sub-objects
480 * of the top-level file object are first class cl_objects, they have their
481 * own radix trees of pages and hence page is implemented as a sequence of
482 * struct cl_pages's, linked into double-linked list through
483 * cl_page::cp_parent and cl_page::cp_child pointers, each residing in the
484 * corresponding radix tree at the corresponding logical offset.
486 * cl_page is associated with VM page of the hosting environment (struct
487 * page in Linux kernel, for example), struct page. It is assumed, that this
488 * association is implemented by one of cl_page layers (top layer in the
489 * current design) that
491 * - intercepts per-VM-page call-backs made by the environment (e.g.,
494 * - translates state (page flag bits) and locking between lustre and
497 * The association between cl_page and struct page is immutable and
498 * established when cl_page is created.
500 * cl_page can be "owned" by a particular cl_io (see below), guaranteeing
501 * this io an exclusive access to this page w.r.t. other io attempts and
502 * various events changing page state (such as transfer completion, or
503 * eviction of the page from the memory). Note, that in general cl_io
504 * cannot be identified with a particular thread, and page ownership is not
505 * exactly equal to the current thread holding a lock on the page. Layer
506 * implementing association between cl_page and struct page has to implement
507 * ownership on top of available synchronization mechanisms.
509 * While lustre client maintains the notion of an page ownership by io,
510 * hosting MM/VM usually has its own page concurrency control
511 * mechanisms. For example, in Linux, page access is synchronized by the
512 * per-page PG_locked bit-lock, and generic kernel code (generic_file_*())
513 * takes care to acquire and release such locks as necessary around the
514 * calls to the file system methods (->readpage(), ->prepare_write(),
515 * ->commit_write(), etc.). This leads to the situation when there are two
516 * different ways to own a page in the client:
518 * - client code explicitly and voluntary owns the page (cl_page_own());
520 * - VM locks a page and then calls the client, that has "to assume"
521 * the ownership from the VM (cl_page_assume()).
523 * Dual methods to release ownership are cl_page_disown() and
524 * cl_page_unassume().
526 * cl_page is reference counted (cl_page::cp_ref). When reference counter
527 * drops to 0, the page is returned to the cache, unless it is in
528 * cl_page_state::CPS_FREEING state, in which case it is immediately
531 * The general logic guaranteeing the absence of "existential races" for
532 * pages is the following:
534 * - there are fixed known ways for a thread to obtain a new reference
537 * - by doing a lookup in the cl_object radix tree, protected by the
540 * - by starting from VM-locked struct page and following some
541 * hosting environment method (e.g., following ->private pointer in
542 * the case of Linux kernel), see cl_vmpage_page();
544 * - when the page enters cl_page_state::CPS_FREEING state, all these
545 * ways are severed with the proper synchronization
546 * (cl_page_delete());
548 * - entry into cl_page_state::CPS_FREEING is serialized by the VM page
551 * - no new references to the page in cl_page_state::CPS_FREEING state
552 * are allowed (checked in cl_page_get()).
554 * Together this guarantees that when last reference to a
555 * cl_page_state::CPS_FREEING page is released, it is safe to destroy the
556 * page, as neither references to it can be acquired at that point, nor
559 * cl_page is a state machine. States are enumerated in enum
560 * cl_page_state. Possible state transitions are enumerated in
561 * cl_page_state_set(). State transition process (i.e., actual changing of
562 * cl_page::cp_state field) is protected by the lock on the underlying VM
565 * Linux Kernel implementation.
567 * Binding between cl_page and struct page (which is a typedef for
568 * struct page) is implemented in the vvp layer. cl_page is attached to the
569 * ->private pointer of the struct page, together with the setting of
570 * PG_private bit in page->flags, and acquiring additional reference on the
571 * struct page (much like struct buffer_head, or any similar file system
572 * private data structures).
574 * PG_locked lock is used to implement both ownership and transfer
575 * synchronization, that is, page is VM-locked in CPS_{OWNED,PAGE{IN,OUT}}
576 * states. No additional references are acquired for the duration of the
579 * \warning *THIS IS NOT* the behavior expected by the Linux kernel, where
580 * write-out is "protected" by the special PG_writeback bit.
584 * States of cl_page. cl_page.c assumes particular order here.
586 * The page state machine is rather crude, as it doesn't recognize finer page
587 * states like "dirty" or "up to date". This is because such states are not
588 * always well defined for the whole stack (see, for example, the
589 * implementation of the read-ahead, that hides page up-to-dateness to track
590 * cache hits accurately). Such sub-states are maintained by the layers that
591 * are interested in them.
595 * Page is in the cache, un-owned. Page leaves cached state in the
598 * - [cl_page_state::CPS_OWNED] io comes across the page and
601 * - [cl_page_state::CPS_PAGEOUT] page is dirty, the
602 * req-formation engine decides that it wants to include this page
603 * into an cl_req being constructed, and yanks it from the cache;
605 * - [cl_page_state::CPS_FREEING] VM callback is executed to
606 * evict the page form the memory;
608 * \invariant cl_page::cp_owner == NULL && cl_page::cp_req == NULL
612 * Page is exclusively owned by some cl_io. Page may end up in this
613 * state as a result of
615 * - io creating new page and immediately owning it;
617 * - [cl_page_state::CPS_CACHED] io finding existing cached page
620 * - [cl_page_state::CPS_OWNED] io finding existing owned page
621 * and waiting for owner to release the page;
623 * Page leaves owned state in the following cases:
625 * - [cl_page_state::CPS_CACHED] io decides to leave the page in
626 * the cache, doing nothing;
628 * - [cl_page_state::CPS_PAGEIN] io starts read transfer for
631 * - [cl_page_state::CPS_PAGEOUT] io starts immediate write
632 * transfer for this page;
634 * - [cl_page_state::CPS_FREEING] io decides to destroy this
635 * page (e.g., as part of truncate or extent lock cancellation).
637 * \invariant cl_page::cp_owner != NULL && cl_page::cp_req == NULL
641 * Page is being written out, as a part of a transfer. This state is
642 * entered when req-formation logic decided that it wants this page to
643 * be sent through the wire _now_. Specifically, it means that once
644 * this state is achieved, transfer completion handler (with either
645 * success or failure indication) is guaranteed to be executed against
646 * this page independently of any locks and any scheduling decisions
647 * made by the hosting environment (that effectively means that the
648 * page is never put into cl_page_state::CPS_PAGEOUT state "in
649 * advance". This property is mentioned, because it is important when
650 * reasoning about possible dead-locks in the system). The page can
651 * enter this state as a result of
653 * - [cl_page_state::CPS_OWNED] an io requesting an immediate
654 * write-out of this page, or
656 * - [cl_page_state::CPS_CACHED] req-forming engine deciding
657 * that it has enough dirty pages cached to issue a "good"
660 * The page leaves cl_page_state::CPS_PAGEOUT state when the transfer
661 * is completed---it is moved into cl_page_state::CPS_CACHED state.
663 * Underlying VM page is locked for the duration of transfer.
665 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL
669 * Page is being read in, as a part of a transfer. This is quite
670 * similar to the cl_page_state::CPS_PAGEOUT state, except that
671 * read-in is always "immediate"---there is no such thing a sudden
672 * construction of read cl_req from cached, presumably not up to date,
675 * Underlying VM page is locked for the duration of transfer.
677 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL
681 * Page is being destroyed. This state is entered when client decides
682 * that page has to be deleted from its host object, as, e.g., a part
685 * Once this state is reached, there is no way to escape it.
687 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req == NULL
694 /** Host page, the page is from the host inode which the cl_page
698 /** Transient page, the transient cl_page is used to bind a cl_page
699 * to vmpage which is not belonging to the same object of cl_page.
700 * it is used in DirectIO, lockless IO and liblustre. */
705 * Fields are protected by the lock on struct page, except for atomics and
708 * \invariant Data type invariants are in cl_page_invariant(). Basically:
709 * cl_page::cp_parent and cl_page::cp_child are a well-formed double-linked
710 * list, consistent with the parent/child pointers in the cl_page::cp_obj and
711 * cl_page::cp_owner (when set).
714 /** Reference counter. */
716 /** Transfer error. */
718 /** An object this page is a part of. Immutable after creation. */
719 struct cl_object *cp_obj;
721 struct page *cp_vmpage;
722 /** Linkage of pages within group. Pages must be owned */
723 struct list_head cp_batch;
724 /** List of slices. Immutable after creation. */
725 struct list_head cp_layers;
726 /** Linkage of pages within cl_req. */
727 struct list_head cp_flight;
729 * Page state. This field is const to avoid accidental update, it is
730 * modified only internally within cl_page.c. Protected by a VM lock.
732 const enum cl_page_state cp_state;
734 * Page type. Only CPT_TRANSIENT is used so far. Immutable after
737 enum cl_page_type cp_type;
740 * Owning IO in cl_page_state::CPS_OWNED state. Sub-page can be owned
741 * by sub-io. Protected by a VM lock.
743 struct cl_io *cp_owner;
745 * Owning IO request in cl_page_state::CPS_PAGEOUT and
746 * cl_page_state::CPS_PAGEIN states. This field is maintained only in
747 * the top-level pages. Protected by a VM lock.
749 struct cl_req *cp_req;
750 /** List of references to this page, for debugging. */
751 struct lu_ref cp_reference;
752 /** Link to an object, for debugging. */
753 struct lu_ref_link cp_obj_ref;
754 /** Link to a queue, for debugging. */
755 struct lu_ref_link cp_queue_ref;
756 /** Assigned if doing a sync_io */
757 struct cl_sync_io *cp_sync_io;
761 * Per-layer part of cl_page.
763 * \see vvp_page, lov_page, osc_page
765 struct cl_page_slice {
766 struct cl_page *cpl_page;
769 * Object slice corresponding to this page slice. Immutable after
772 struct cl_object *cpl_obj;
773 const struct cl_page_operations *cpl_ops;
774 /** Linkage into cl_page::cp_layers. Immutable after creation. */
775 struct list_head cpl_linkage;
779 * Lock mode. For the client extent locks.
791 * Requested transfer type.
801 * Per-layer page operations.
803 * Methods taking an \a io argument are for the activity happening in the
804 * context of given \a io. Page is assumed to be owned by that io, except for
805 * the obvious cases (like cl_page_operations::cpo_own()).
807 * \see vvp_page_ops, lov_page_ops, osc_page_ops
809 struct cl_page_operations {
811 * cl_page<->struct page methods. Only one layer in the stack has to
812 * implement these. Current code assumes that this functionality is
813 * provided by the topmost layer, see cl_page_disown0() as an example.
817 * Called when \a io acquires this page into the exclusive
818 * ownership. When this method returns, it is guaranteed that the is
819 * not owned by other io, and no transfer is going on against
823 * \see vvp_page_own(), lov_page_own()
825 int (*cpo_own)(const struct lu_env *env,
826 const struct cl_page_slice *slice,
827 struct cl_io *io, int nonblock);
828 /** Called when ownership it yielded. Optional.
830 * \see cl_page_disown()
831 * \see vvp_page_disown()
833 void (*cpo_disown)(const struct lu_env *env,
834 const struct cl_page_slice *slice, struct cl_io *io);
836 * Called for a page that is already "owned" by \a io from VM point of
839 * \see cl_page_assume()
840 * \see vvp_page_assume(), lov_page_assume()
842 void (*cpo_assume)(const struct lu_env *env,
843 const struct cl_page_slice *slice, struct cl_io *io);
844 /** Dual to cl_page_operations::cpo_assume(). Optional. Called
845 * bottom-to-top when IO releases a page without actually unlocking
848 * \see cl_page_unassume()
849 * \see vvp_page_unassume()
851 void (*cpo_unassume)(const struct lu_env *env,
852 const struct cl_page_slice *slice,
855 * Announces whether the page contains valid data or not by \a uptodate.
857 * \see cl_page_export()
858 * \see vvp_page_export()
860 void (*cpo_export)(const struct lu_env *env,
861 const struct cl_page_slice *slice, int uptodate);
863 * Checks whether underlying VM page is locked (in the suitable
864 * sense). Used for assertions.
866 * \retval -EBUSY: page is protected by a lock of a given mode;
867 * \retval -ENODATA: page is not protected by a lock;
868 * \retval 0: this layer cannot decide. (Should never happen.)
870 int (*cpo_is_vmlocked)(const struct lu_env *env,
871 const struct cl_page_slice *slice);
877 * Called when page is truncated from the object. Optional.
879 * \see cl_page_discard()
880 * \see vvp_page_discard(), osc_page_discard()
882 void (*cpo_discard)(const struct lu_env *env,
883 const struct cl_page_slice *slice,
886 * Called when page is removed from the cache, and is about to being
887 * destroyed. Optional.
889 * \see cl_page_delete()
890 * \see vvp_page_delete(), osc_page_delete()
892 void (*cpo_delete)(const struct lu_env *env,
893 const struct cl_page_slice *slice);
894 /** Destructor. Frees resources and slice itself. */
895 void (*cpo_fini)(const struct lu_env *env,
896 struct cl_page_slice *slice);
899 * Checks whether the page is protected by a cl_lock. This is a
900 * per-layer method, because certain layers have ways to check for the
901 * lock much more efficiently than through the generic locks scan, or
902 * implement locking mechanisms separate from cl_lock, e.g.,
903 * LL_FILE_GROUP_LOCKED in vvp. If \a pending is true, check for locks
904 * being canceled, or scheduled for cancellation as soon as the last
905 * user goes away, too.
907 * \retval -EBUSY: page is protected by a lock of a given mode;
908 * \retval -ENODATA: page is not protected by a lock;
909 * \retval 0: this layer cannot decide.
911 * \see cl_page_is_under_lock()
913 int (*cpo_is_under_lock)(const struct lu_env *env,
914 const struct cl_page_slice *slice,
915 struct cl_io *io, pgoff_t *max);
918 * Optional debugging helper. Prints given page slice.
920 * \see cl_page_print()
922 int (*cpo_print)(const struct lu_env *env,
923 const struct cl_page_slice *slice,
924 void *cookie, lu_printer_t p);
928 * Transfer methods. See comment on cl_req for a description of
929 * transfer formation and life-cycle.
934 * Request type dependent vector of operations.
936 * Transfer operations depend on transfer mode (cl_req_type). To avoid
937 * passing transfer mode to each and every of these methods, and to
938 * avoid branching on request type inside of the methods, separate
939 * methods for cl_req_type:CRT_READ and cl_req_type:CRT_WRITE are
940 * provided. That is, method invocation usually looks like
942 * slice->cp_ops.io[req->crq_type].cpo_method(env, slice, ...);
946 * Called when a page is submitted for a transfer as a part of
949 * \return 0 : page is eligible for submission;
950 * \return -EALREADY : skip this page;
951 * \return -ve : error.
953 * \see cl_page_prep()
955 int (*cpo_prep)(const struct lu_env *env,
956 const struct cl_page_slice *slice,
959 * Completion handler. This is guaranteed to be eventually
960 * fired after cl_page_operations::cpo_prep() or
961 * cl_page_operations::cpo_make_ready() call.
963 * This method can be called in a non-blocking context. It is
964 * guaranteed however, that the page involved and its object
965 * are pinned in memory (and, hence, calling cl_page_put() is
968 * \see cl_page_completion()
970 void (*cpo_completion)(const struct lu_env *env,
971 const struct cl_page_slice *slice,
974 * Called when cached page is about to be added to the
975 * cl_req as a part of req formation.
977 * \return 0 : proceed with this page;
978 * \return -EAGAIN : skip this page;
979 * \return -ve : error.
981 * \see cl_page_make_ready()
983 int (*cpo_make_ready)(const struct lu_env *env,
984 const struct cl_page_slice *slice);
987 * Tell transfer engine that only [to, from] part of a page should be
990 * This is used for immediate transfers.
992 * \todo XXX this is not very good interface. It would be much better
993 * if all transfer parameters were supplied as arguments to
994 * cl_io_operations::cio_submit() call, but it is not clear how to do
995 * this for page queues.
997 * \see cl_page_clip()
999 void (*cpo_clip)(const struct lu_env *env,
1000 const struct cl_page_slice *slice,
1003 * \pre the page was queued for transferring.
1004 * \post page is removed from client's pending list, or -EBUSY
1005 * is returned if it has already been in transferring.
1007 * This is one of seldom page operation which is:
1008 * 0. called from top level;
1009 * 1. don't have vmpage locked;
1010 * 2. every layer should synchronize execution of its ->cpo_cancel()
1011 * with completion handlers. Osc uses client obd lock for this
1012 * purpose. Based on there is no vvp_page_cancel and
1013 * lov_page_cancel(), cpo_cancel is defacto protected by client lock.
1015 * \see osc_page_cancel().
1017 int (*cpo_cancel)(const struct lu_env *env,
1018 const struct cl_page_slice *slice);
1020 * Write out a page by kernel. This is only called by ll_writepage
1023 * \see cl_page_flush()
1025 int (*cpo_flush)(const struct lu_env *env,
1026 const struct cl_page_slice *slice,
1032 * Helper macro, dumping detailed information about \a page into a log.
1034 #define CL_PAGE_DEBUG(mask, env, page, format, ...) \
1036 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1037 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1038 cl_page_print(env, &msgdata, lu_cdebug_printer, page); \
1039 CDEBUG(mask, format , ## __VA_ARGS__); \
1044 * Helper macro, dumping shorter information about \a page into a log.
1046 #define CL_PAGE_HEADER(mask, env, page, format, ...) \
1048 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1049 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1050 cl_page_header_print(env, &msgdata, lu_cdebug_printer, page); \
1051 CDEBUG(mask, format , ## __VA_ARGS__); \
1055 static inline struct page *cl_page_vmpage(const struct cl_page *page)
1057 LASSERT(page->cp_vmpage != NULL);
1058 return page->cp_vmpage;
1062 * Check if a cl_page is in use.
1064 * Client cache holds a refcount, this refcount will be dropped when
1065 * the page is taken out of cache, see vvp_page_delete().
1067 static inline bool __page_in_use(const struct cl_page *page, int refc)
1069 return (atomic_read(&page->cp_ref) > refc + 1);
1073 * Caller itself holds a refcount of cl_page.
1075 #define cl_page_in_use(pg) __page_in_use(pg, 1)
1077 * Caller doesn't hold a refcount.
1079 #define cl_page_in_use_noref(pg) __page_in_use(pg, 0)
1083 /** \addtogroup cl_lock cl_lock
1087 * Extent locking on the client.
1091 * The locking model of the new client code is built around
1095 * data-type representing an extent lock on a regular file. cl_lock is a
1096 * layered object (much like cl_object and cl_page), it consists of a header
1097 * (struct cl_lock) and a list of layers (struct cl_lock_slice), linked to
1098 * cl_lock::cll_layers list through cl_lock_slice::cls_linkage.
1100 * Typical cl_lock consists of the two layers:
1102 * - vvp_lock (vvp specific data), and
1103 * - lov_lock (lov specific data).
1105 * lov_lock contains an array of sub-locks. Each of these sub-locks is a
1106 * normal cl_lock: it has a header (struct cl_lock) and a list of layers:
1108 * - lovsub_lock, and
1111 * Each sub-lock is associated with a cl_object (representing stripe
1112 * sub-object or the file to which top-level cl_lock is associated to), and is
1113 * linked into that cl_object::coh_locks. In this respect cl_lock is similar to
1114 * cl_object (that at lov layer also fans out into multiple sub-objects), and
1115 * is different from cl_page, that doesn't fan out (there is usually exactly
1116 * one osc_page for every vvp_page). We shall call vvp-lov portion of the lock
1117 * a "top-lock" and its lovsub-osc portion a "sub-lock".
1121 * cl_lock is a cacheless data container for the requirements of locks to
1122 * complete the IO. cl_lock is created before I/O starts and destroyed when the
1125 * cl_lock depends on LDLM lock to fulfill lock semantics. LDLM lock is attached
1126 * to cl_lock at OSC layer. LDLM lock is still cacheable.
1128 * INTERFACE AND USAGE
1130 * Two major methods are supported for cl_lock: clo_enqueue and clo_cancel. A
1131 * cl_lock is enqueued by cl_lock_request(), which will call clo_enqueue()
1132 * methods for each layer to enqueue the lock. At the LOV layer, if a cl_lock
1133 * consists of multiple sub cl_locks, each sub locks will be enqueued
1134 * correspondingly. At OSC layer, the lock enqueue request will tend to reuse
1135 * cached LDLM lock; otherwise a new LDLM lock will have to be requested from
1138 * cl_lock_cancel() must be called to release a cl_lock after use. clo_cancel()
1139 * method will be called for each layer to release the resource held by this
1140 * lock. At OSC layer, the reference count of LDLM lock, which is held at
1141 * clo_enqueue time, is released.
1143 * LDLM lock can only be canceled if there is no cl_lock using it.
1145 * Overall process of the locking during IO operation is as following:
1147 * - once parameters for IO are setup in cl_io, cl_io_operations::cio_lock()
1148 * is called on each layer. Responsibility of this method is to add locks,
1149 * needed by a given layer into cl_io.ci_lockset.
1151 * - once locks for all layers were collected, they are sorted to avoid
1152 * dead-locks (cl_io_locks_sort()), and enqueued.
1154 * - when all locks are acquired, IO is performed;
1156 * - locks are released after IO is complete.
1158 * Striping introduces major additional complexity into locking. The
1159 * fundamental problem is that it is generally unsafe to actively use (hold)
1160 * two locks on the different OST servers at the same time, as this introduces
1161 * inter-server dependency and can lead to cascading evictions.
1163 * Basic solution is to sub-divide large read/write IOs into smaller pieces so
1164 * that no multi-stripe locks are taken (note that this design abandons POSIX
1165 * read/write semantics). Such pieces ideally can be executed concurrently. At
1166 * the same time, certain types of IO cannot be sub-divived, without
1167 * sacrificing correctness. This includes:
1169 * - O_APPEND write, where [0, EOF] lock has to be taken, to guarantee
1172 * - ftruncate(fd, offset), where [offset, EOF] lock has to be taken.
1174 * Also, in the case of read(fd, buf, count) or write(fd, buf, count), where
1175 * buf is a part of memory mapped Lustre file, a lock or locks protecting buf
1176 * has to be held together with the usual lock on [offset, offset + count].
1178 * Interaction with DLM
1180 * In the expected setup, cl_lock is ultimately backed up by a collection of
1181 * DLM locks (struct ldlm_lock). Association between cl_lock and DLM lock is
1182 * implemented in osc layer, that also matches DLM events (ASTs, cancellation,
1183 * etc.) into cl_lock_operation calls. See struct osc_lock for a more detailed
1184 * description of interaction with DLM.
1190 struct cl_lock_descr {
1191 /** Object this lock is granted for. */
1192 struct cl_object *cld_obj;
1193 /** Index of the first page protected by this lock. */
1195 /** Index of the last page (inclusive) protected by this lock. */
1197 /** Group ID, for group lock */
1200 enum cl_lock_mode cld_mode;
1202 * flags to enqueue lock. A combination of bit-flags from
1203 * enum cl_enq_flags.
1205 __u32 cld_enq_flags;
1208 #define DDESCR "%s(%d):[%lu, %lu]:%x"
1209 #define PDESCR(descr) \
1210 cl_lock_mode_name((descr)->cld_mode), (descr)->cld_mode, \
1211 (descr)->cld_start, (descr)->cld_end, (descr)->cld_enq_flags
1213 const char *cl_lock_mode_name(const enum cl_lock_mode mode);
1216 * Layered client lock.
1219 /** List of slices. Immutable after creation. */
1220 struct list_head cll_layers;
1221 /** lock attribute, extent, cl_object, etc. */
1222 struct cl_lock_descr cll_descr;
1226 * Per-layer part of cl_lock
1228 * \see vvp_lock, lov_lock, lovsub_lock, osc_lock
1230 struct cl_lock_slice {
1231 struct cl_lock *cls_lock;
1232 /** Object slice corresponding to this lock slice. Immutable after
1234 struct cl_object *cls_obj;
1235 const struct cl_lock_operations *cls_ops;
1236 /** Linkage into cl_lock::cll_layers. Immutable after creation. */
1237 struct list_head cls_linkage;
1242 * \see vvp_lock_ops, lov_lock_ops, lovsub_lock_ops, osc_lock_ops
1244 struct cl_lock_operations {
1247 * Attempts to enqueue the lock. Called top-to-bottom.
1249 * \retval 0 this layer has enqueued the lock successfully
1250 * \retval >0 this layer has enqueued the lock, but need to wait on
1251 * @anchor for resources
1252 * \retval -ve failure
1254 * \see vvp_lock_enqueue(), lov_lock_enqueue(), lovsub_lock_enqueue(),
1255 * \see osc_lock_enqueue()
1257 int (*clo_enqueue)(const struct lu_env *env,
1258 const struct cl_lock_slice *slice,
1259 struct cl_io *io, struct cl_sync_io *anchor);
1261 * Cancel a lock, release its DLM lock ref, while does not cancel the
1264 void (*clo_cancel)(const struct lu_env *env,
1265 const struct cl_lock_slice *slice);
1268 * Destructor. Frees resources and the slice.
1270 * \see vvp_lock_fini(), lov_lock_fini(), lovsub_lock_fini(),
1271 * \see osc_lock_fini()
1273 void (*clo_fini)(const struct lu_env *env, struct cl_lock_slice *slice);
1275 * Optional debugging helper. Prints given lock slice.
1277 int (*clo_print)(const struct lu_env *env,
1278 void *cookie, lu_printer_t p,
1279 const struct cl_lock_slice *slice);
1282 #define CL_LOCK_DEBUG(mask, env, lock, format, ...) \
1284 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1285 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1286 cl_lock_print(env, &msgdata, lu_cdebug_printer, lock); \
1287 CDEBUG(mask, format , ## __VA_ARGS__); \
1291 #define CL_LOCK_ASSERT(expr, env, lock) do { \
1295 CL_LOCK_DEBUG(D_ERROR, env, lock, "failed at %s.\n", #expr); \
1301 /** \addtogroup cl_page_list cl_page_list
1302 * Page list used to perform collective operations on a group of pages.
1304 * Pages are added to the list one by one. cl_page_list acquires a reference
1305 * for every page in it. Page list is used to perform collective operations on
1308 * - submit pages for an immediate transfer,
1310 * - own pages on behalf of certain io (waiting for each page in turn),
1314 * When list is finalized, it releases references on all pages it still has.
1316 * \todo XXX concurrency control.
1320 struct cl_page_list {
1322 struct list_head pl_pages;
1323 struct task_struct *pl_owner;
1327 * A 2-queue of pages. A convenience data-type for common use case, 2-queue
1328 * contains an incoming page list and an outgoing page list.
1331 struct cl_page_list c2_qin;
1332 struct cl_page_list c2_qout;
1335 /** @} cl_page_list */
1337 /** \addtogroup cl_io cl_io
1342 * cl_io represents a high level I/O activity like
1343 * read(2)/write(2)/truncate(2) system call, or cancellation of an extent
1346 * cl_io is a layered object, much like cl_{object,page,lock} but with one
1347 * important distinction. We want to minimize number of calls to the allocator
1348 * in the fast path, e.g., in the case of read(2) when everything is cached:
1349 * client already owns the lock over region being read, and data are cached
1350 * due to read-ahead. To avoid allocation of cl_io layers in such situations,
1351 * per-layer io state is stored in the session, associated with the io, see
1352 * struct {vvp,lov,osc}_io for example. Sessions allocation is amortized
1353 * by using free-lists, see cl_env_get().
1355 * There is a small predefined number of possible io types, enumerated in enum
1358 * cl_io is a state machine, that can be advanced concurrently by the multiple
1359 * threads. It is up to these threads to control the concurrency and,
1360 * specifically, to detect when io is done, and its state can be safely
1363 * For read/write io overall execution plan is as following:
1365 * (0) initialize io state through all layers;
1367 * (1) loop: prepare chunk of work to do
1369 * (2) call all layers to collect locks they need to process current chunk
1371 * (3) sort all locks to avoid dead-locks, and acquire them
1373 * (4) process the chunk: call per-page methods
1374 * (cl_io_operations::cio_read_page() for read,
1375 * cl_io_operations::cio_prepare_write(),
1376 * cl_io_operations::cio_commit_write() for write)
1382 * To implement the "parallel IO mode", lov layer creates sub-io's (lazily to
1383 * address allocation efficiency issues mentioned above), and returns with the
1384 * special error condition from per-page method when current sub-io has to
1385 * block. This causes io loop to be repeated, and lov switches to the next
1386 * sub-io in its cl_io_operations::cio_iter_init() implementation.
1391 /** read system call */
1393 /** write system call */
1395 /** truncate, utime system calls */
1398 * page fault handling
1402 * fsync system call handling
1403 * To write out a range of file
1407 * Miscellaneous io. This is used for occasional io activity that
1408 * doesn't fit into other types. Currently this is used for:
1410 * - cancellation of an extent lock. This io exists as a context
1411 * to write dirty pages from under the lock being canceled back
1414 * - VM induced page write-out. An io context for writing page out
1415 * for memory cleansing;
1417 * - glimpse. An io context to acquire glimpse lock.
1419 * - grouplock. An io context to acquire group lock.
1421 * CIT_MISC io is used simply as a context in which locks and pages
1422 * are manipulated. Such io has no internal "process", that is,
1423 * cl_io_loop() is never called for it.
1430 * States of cl_io state machine
1433 /** Not initialized. */
1437 /** IO iteration started. */
1441 /** Actual IO is in progress. */
1443 /** IO for the current iteration finished. */
1445 /** Locks released. */
1447 /** Iteration completed. */
1449 /** cl_io finalized. */
1454 * IO state private for a layer.
1456 * This is usually embedded into layer session data, rather than allocated
1459 * \see vvp_io, lov_io, osc_io
1461 struct cl_io_slice {
1462 struct cl_io *cis_io;
1463 /** corresponding object slice. Immutable after creation. */
1464 struct cl_object *cis_obj;
1465 /** io operations. Immutable after creation. */
1466 const struct cl_io_operations *cis_iop;
1468 * linkage into a list of all slices for a given cl_io, hanging off
1469 * cl_io::ci_layers. Immutable after creation.
1471 struct list_head cis_linkage;
1474 typedef void (*cl_commit_cbt)(const struct lu_env *, struct cl_io *,
1478 * Per-layer io operations.
1479 * \see vvp_io_ops, lov_io_ops, lovsub_io_ops, osc_io_ops
1481 struct cl_io_operations {
1483 * Vector of io state transition methods for every io type.
1485 * \see cl_page_operations::io
1489 * Prepare io iteration at a given layer.
1491 * Called top-to-bottom at the beginning of each iteration of
1492 * "io loop" (if it makes sense for this type of io). Here
1493 * layer selects what work it will do during this iteration.
1495 * \see cl_io_operations::cio_iter_fini()
1497 int (*cio_iter_init) (const struct lu_env *env,
1498 const struct cl_io_slice *slice);
1500 * Finalize io iteration.
1502 * Called bottom-to-top at the end of each iteration of "io
1503 * loop". Here layers can decide whether IO has to be
1506 * \see cl_io_operations::cio_iter_init()
1508 void (*cio_iter_fini) (const struct lu_env *env,
1509 const struct cl_io_slice *slice);
1511 * Collect locks for the current iteration of io.
1513 * Called top-to-bottom to collect all locks necessary for
1514 * this iteration. This methods shouldn't actually enqueue
1515 * anything, instead it should post a lock through
1516 * cl_io_lock_add(). Once all locks are collected, they are
1517 * sorted and enqueued in the proper order.
1519 int (*cio_lock) (const struct lu_env *env,
1520 const struct cl_io_slice *slice);
1522 * Finalize unlocking.
1524 * Called bottom-to-top to finish layer specific unlocking
1525 * functionality, after generic code released all locks
1526 * acquired by cl_io_operations::cio_lock().
1528 void (*cio_unlock)(const struct lu_env *env,
1529 const struct cl_io_slice *slice);
1531 * Start io iteration.
1533 * Once all locks are acquired, called top-to-bottom to
1534 * commence actual IO. In the current implementation,
1535 * top-level vvp_io_{read,write}_start() does all the work
1536 * synchronously by calling generic_file_*(), so other layers
1537 * are called when everything is done.
1539 int (*cio_start)(const struct lu_env *env,
1540 const struct cl_io_slice *slice);
1542 * Called top-to-bottom at the end of io loop. Here layer
1543 * might wait for an unfinished asynchronous io.
1545 void (*cio_end) (const struct lu_env *env,
1546 const struct cl_io_slice *slice);
1548 * Called bottom-to-top to notify layers that read/write IO
1549 * iteration finished, with \a nob bytes transferred.
1551 void (*cio_advance)(const struct lu_env *env,
1552 const struct cl_io_slice *slice,
1555 * Called once per io, bottom-to-top to release io resources.
1557 void (*cio_fini) (const struct lu_env *env,
1558 const struct cl_io_slice *slice);
1562 * Submit pages from \a queue->c2_qin for IO, and move
1563 * successfully submitted pages into \a queue->c2_qout. Return
1564 * non-zero if failed to submit even the single page. If
1565 * submission failed after some pages were moved into \a
1566 * queue->c2_qout, completion callback with non-zero ioret is
1569 int (*cio_submit)(const struct lu_env *env,
1570 const struct cl_io_slice *slice,
1571 enum cl_req_type crt,
1572 struct cl_2queue *queue);
1574 * Queue async page for write.
1575 * The difference between cio_submit and cio_queue is that
1576 * cio_submit is for urgent request.
1578 int (*cio_commit_async)(const struct lu_env *env,
1579 const struct cl_io_slice *slice,
1580 struct cl_page_list *queue, int from, int to,
1583 * Read missing page.
1585 * Called by a top-level cl_io_operations::op[CIT_READ]::cio_start()
1586 * method, when it hits not-up-to-date page in the range. Optional.
1588 * \pre io->ci_type == CIT_READ
1590 int (*cio_read_page)(const struct lu_env *env,
1591 const struct cl_io_slice *slice,
1592 const struct cl_page_slice *page);
1594 * Optional debugging helper. Print given io slice.
1596 int (*cio_print)(const struct lu_env *env, void *cookie,
1597 lu_printer_t p, const struct cl_io_slice *slice);
1601 * Flags to lock enqueue procedure.
1606 * instruct server to not block, if conflicting lock is found. Instead
1607 * -EWOULDBLOCK is returned immediately.
1609 CEF_NONBLOCK = 0x00000001,
1611 * take lock asynchronously (out of order), as it cannot
1612 * deadlock. This is for LDLM_FL_HAS_INTENT locks used for glimpsing.
1614 CEF_ASYNC = 0x00000002,
1616 * tell the server to instruct (though a flag in the blocking ast) an
1617 * owner of the conflicting lock, that it can drop dirty pages
1618 * protected by this lock, without sending them to the server.
1620 CEF_DISCARD_DATA = 0x00000004,
1622 * tell the sub layers that it must be a `real' lock. This is used for
1623 * mmapped-buffer locks and glimpse locks that must be never converted
1624 * into lockless mode.
1626 * \see vvp_mmap_locks(), cl_glimpse_lock().
1628 CEF_MUST = 0x00000008,
1630 * tell the sub layers that never request a `real' lock. This flag is
1631 * not used currently.
1633 * cl_io::ci_lockreq and CEF_{MUST,NEVER} flags specify lockless
1634 * conversion policy: ci_lockreq describes generic information of lock
1635 * requirement for this IO, especially for locks which belong to the
1636 * object doing IO; however, lock itself may have precise requirements
1637 * that are described by the enqueue flags.
1639 CEF_NEVER = 0x00000010,
1641 * for async glimpse lock.
1643 CEF_AGL = 0x00000020,
1645 * enqueue a lock to test DLM lock existence.
1647 CEF_PEEK = 0x00000040,
1649 * mask of enq_flags.
1651 CEF_MASK = 0x0000007f,
1655 * Link between lock and io. Intermediate structure is needed, because the
1656 * same lock can be part of multiple io's simultaneously.
1658 struct cl_io_lock_link {
1659 /** linkage into one of cl_lockset lists. */
1660 struct list_head cill_linkage;
1661 struct cl_lock cill_lock;
1662 /** optional destructor */
1663 void (*cill_fini)(const struct lu_env *env,
1664 struct cl_io_lock_link *link);
1666 #define cill_descr cill_lock.cll_descr
1669 * Lock-set represents a collection of locks, that io needs at a
1670 * time. Generally speaking, client tries to avoid holding multiple locks when
1673 * - holding extent locks over multiple ost's introduces the danger of
1674 * "cascading timeouts";
1676 * - holding multiple locks over the same ost is still dead-lock prone,
1677 * see comment in osc_lock_enqueue(),
1679 * but there are certain situations where this is unavoidable:
1681 * - O_APPEND writes have to take [0, EOF] lock for correctness;
1683 * - truncate has to take [new-size, EOF] lock for correctness;
1685 * - SNS has to take locks across full stripe for correctness;
1687 * - in the case when user level buffer, supplied to {read,write}(file0),
1688 * is a part of a memory mapped lustre file, client has to take a dlm
1689 * locks on file0, and all files that back up the buffer (or a part of
1690 * the buffer, that is being processed in the current chunk, in any
1691 * case, there are situations where at least 2 locks are necessary).
1693 * In such cases we at least try to take locks in the same consistent
1694 * order. To this end, all locks are first collected, then sorted, and then
1698 /** locks to be acquired. */
1699 struct list_head cls_todo;
1700 /** locks acquired. */
1701 struct list_head cls_done;
1705 * Lock requirements(demand) for IO. It should be cl_io_lock_req,
1706 * but 'req' is always to be thought as 'request' :-)
1708 enum cl_io_lock_dmd {
1709 /** Always lock data (e.g., O_APPEND). */
1711 /** Layers are free to decide between local and global locking. */
1713 /** Never lock: there is no cache (e.g., liblustre). */
1717 enum cl_fsync_mode {
1718 /** start writeback, do not wait for them to finish */
1720 /** start writeback and wait for them to finish */
1722 /** discard all of dirty pages in a specific file range */
1723 CL_FSYNC_DISCARD = 2,
1724 /** start writeback and make sure they have reached storage before
1725 * return. OST_SYNC RPC must be issued and finished */
1729 struct cl_io_rw_common {
1739 * cl_io is shared by all threads participating in this IO (in current
1740 * implementation only one thread advances IO, but parallel IO design and
1741 * concurrent copy_*_user() require multiple threads acting on the same IO. It
1742 * is up to these threads to serialize their activities, including updates to
1743 * mutable cl_io fields.
1746 /** type of this IO. Immutable after creation. */
1747 enum cl_io_type ci_type;
1748 /** current state of cl_io state machine. */
1749 enum cl_io_state ci_state;
1750 /** main object this io is against. Immutable after creation. */
1751 struct cl_object *ci_obj;
1753 * Upper layer io, of which this io is a part of. Immutable after
1756 struct cl_io *ci_parent;
1757 /** List of slices. Immutable after creation. */
1758 struct list_head ci_layers;
1759 /** list of locks (to be) acquired by this io. */
1760 struct cl_lockset ci_lockset;
1761 /** lock requirements, this is just a help info for sublayers. */
1762 enum cl_io_lock_dmd ci_lockreq;
1765 struct cl_io_rw_common rd;
1768 struct cl_io_rw_common wr;
1772 struct cl_io_rw_common ci_rw;
1773 struct cl_setattr_io {
1774 struct ost_lvb sa_attr;
1775 unsigned int sa_valid;
1776 int sa_stripe_index;
1777 struct lu_fid *sa_parent_fid;
1778 struct obd_capa *sa_capa;
1780 struct cl_fault_io {
1781 /** page index within file. */
1783 /** bytes valid byte on a faulted page. */
1785 /** writable page? for nopage() only */
1787 /** page of an executable? */
1789 /** page_mkwrite() */
1791 /** resulting page */
1792 struct cl_page *ft_page;
1794 struct cl_fsync_io {
1797 struct obd_capa *fi_capa;
1798 /** file system level fid */
1799 struct lu_fid *fi_fid;
1800 enum cl_fsync_mode fi_mode;
1801 /* how many pages were written/discarded */
1802 unsigned int fi_nr_written;
1805 struct cl_2queue ci_queue;
1808 unsigned int ci_continue:1,
1810 * This io has held grouplock, to inform sublayers that
1811 * don't do lockless i/o.
1815 * The whole IO need to be restarted because layout has been changed
1819 * to not refresh layout - the IO issuer knows that the layout won't
1820 * change(page operations, layout change causes all page to be
1821 * discarded), or it doesn't matter if it changes(sync).
1825 * Check if layout changed after the IO finishes. Mainly for HSM
1826 * requirement. If IO occurs to openning files, it doesn't need to
1827 * verify layout because HSM won't release openning files.
1828 * Right now, only two opertaions need to verify layout: glimpse
1833 * file is released, restore has to to be triggered by vvp layer
1835 ci_restore_needed:1,
1841 * Number of pages owned by this IO. For invariant checking.
1843 unsigned ci_owned_nr;
1848 /** \addtogroup cl_req cl_req
1853 * There are two possible modes of transfer initiation on the client:
1855 * - immediate transfer: this is started when a high level io wants a page
1856 * or a collection of pages to be transferred right away. Examples:
1857 * read-ahead, synchronous read in the case of non-page aligned write,
1858 * page write-out as a part of extent lock cancellation, page write-out
1859 * as a part of memory cleansing. Immediate transfer can be both
1860 * cl_req_type::CRT_READ and cl_req_type::CRT_WRITE;
1862 * - opportunistic transfer (cl_req_type::CRT_WRITE only), that happens
1863 * when io wants to transfer a page to the server some time later, when
1864 * it can be done efficiently. Example: pages dirtied by the write(2)
1867 * In any case, transfer takes place in the form of a cl_req, which is a
1868 * representation for a network RPC.
1870 * Pages queued for an opportunistic transfer are cached until it is decided
1871 * that efficient RPC can be composed of them. This decision is made by "a
1872 * req-formation engine", currently implemented as a part of osc
1873 * layer. Req-formation depends on many factors: the size of the resulting
1874 * RPC, whether or not multi-object RPCs are supported by the server,
1875 * max-rpc-in-flight limitations, size of the dirty cache, etc.
1877 * For the immediate transfer io submits a cl_page_list, that req-formation
1878 * engine slices into cl_req's, possibly adding cached pages to some of
1879 * the resulting req's.
1881 * Whenever a page from cl_page_list is added to a newly constructed req, its
1882 * cl_page_operations::cpo_prep() layer methods are called. At that moment,
1883 * page state is atomically changed from cl_page_state::CPS_OWNED to
1884 * cl_page_state::CPS_PAGEOUT or cl_page_state::CPS_PAGEIN, cl_page::cp_owner
1885 * is zeroed, and cl_page::cp_req is set to the
1886 * req. cl_page_operations::cpo_prep() method at the particular layer might
1887 * return -EALREADY to indicate that it does not need to submit this page
1888 * at all. This is possible, for example, if page, submitted for read,
1889 * became up-to-date in the meantime; and for write, the page don't have
1890 * dirty bit marked. \see cl_io_submit_rw()
1892 * Whenever a cached page is added to a newly constructed req, its
1893 * cl_page_operations::cpo_make_ready() layer methods are called. At that
1894 * moment, page state is atomically changed from cl_page_state::CPS_CACHED to
1895 * cl_page_state::CPS_PAGEOUT, and cl_page::cp_req is set to
1896 * req. cl_page_operations::cpo_make_ready() method at the particular layer
1897 * might return -EAGAIN to indicate that this page is not eligible for the
1898 * transfer right now.
1902 * Plan is to divide transfers into "priority bands" (indicated when
1903 * submitting cl_page_list, and queuing a page for the opportunistic transfer)
1904 * and allow glueing of cached pages to immediate transfers only within single
1905 * band. This would make high priority transfers (like lock cancellation or
1906 * memory pressure induced write-out) really high priority.
1911 * Per-transfer attributes.
1913 struct cl_req_attr {
1914 /** Generic attributes for the server consumption. */
1915 struct obdo *cra_oa;
1917 struct obd_capa *cra_capa;
1919 char cra_jobid[LUSTRE_JOBID_SIZE];
1923 * Transfer request operations definable at every layer.
1925 * Concurrency: transfer formation engine synchronizes calls to all transfer
1928 struct cl_req_operations {
1930 * Invoked top-to-bottom by cl_req_prep() when transfer formation is
1931 * complete (all pages are added).
1933 * \see osc_req_prep()
1935 int (*cro_prep)(const struct lu_env *env,
1936 const struct cl_req_slice *slice);
1938 * Called top-to-bottom to fill in \a oa fields. This is called twice
1939 * with different flags, see bug 10150 and osc_build_req().
1941 * \param obj an object from cl_req which attributes are to be set in
1944 * \param oa struct obdo where attributes are placed
1946 * \param flags \a oa fields to be filled.
1948 void (*cro_attr_set)(const struct lu_env *env,
1949 const struct cl_req_slice *slice,
1950 const struct cl_object *obj,
1951 struct cl_req_attr *attr, u64 flags);
1953 * Called top-to-bottom from cl_req_completion() to notify layers that
1954 * transfer completed. Has to free all state allocated by
1955 * cl_device_operations::cdo_req_init().
1957 void (*cro_completion)(const struct lu_env *env,
1958 const struct cl_req_slice *slice, int ioret);
1962 * A per-object state that (potentially multi-object) transfer request keeps.
1965 /** object itself */
1966 struct cl_object *ro_obj;
1967 /** reference to cl_req_obj::ro_obj. For debugging. */
1968 struct lu_ref_link ro_obj_ref;
1969 /* something else? Number of pages for a given object? */
1975 * Transfer requests are not reference counted, because IO sub-system owns
1976 * them exclusively and knows when to free them.
1980 * cl_req is created by cl_req_alloc() that calls
1981 * cl_device_operations::cdo_req_init() device methods to allocate per-req
1982 * state in every layer.
1984 * Then pages are added (cl_req_page_add()), req keeps track of all objects it
1985 * contains pages for.
1987 * Once all pages were collected, cl_page_operations::cpo_prep() method is
1988 * called top-to-bottom. At that point layers can modify req, let it pass, or
1989 * deny it completely. This is to support things like SNS that have transfer
1990 * ordering requirements invisible to the individual req-formation engine.
1992 * On transfer completion (or transfer timeout, or failure to initiate the
1993 * transfer of an allocated req), cl_req_operations::cro_completion() method
1994 * is called, after execution of cl_page_operations::cpo_completion() of all
1998 enum cl_req_type crq_type;
1999 /** A list of pages being transfered */
2000 struct list_head crq_pages;
2001 /** Number of pages in cl_req::crq_pages */
2002 unsigned crq_nrpages;
2003 /** An array of objects which pages are in ->crq_pages */
2004 struct cl_req_obj *crq_o;
2005 /** Number of elements in cl_req::crq_objs[] */
2006 unsigned crq_nrobjs;
2007 struct list_head crq_layers;
2011 * Per-layer state for request.
2013 struct cl_req_slice {
2014 struct cl_req *crs_req;
2015 struct cl_device *crs_dev;
2016 struct list_head crs_linkage;
2017 const struct cl_req_operations *crs_ops;
2022 enum cache_stats_item {
2023 /** how many cache lookups were performed */
2025 /** how many times cache lookup resulted in a hit */
2027 /** how many entities are in the cache right now */
2029 /** how many entities in the cache are actively used (and cannot be
2030 * evicted) right now */
2032 /** how many entities were created at all */
2037 #define CS_NAMES { "lookup", "hit", "total", "busy", "create" }
2040 * Stats for a generic cache (similar to inode, lu_object, etc. caches).
2042 struct cache_stats {
2043 const char *cs_name;
2044 atomic_t cs_stats[CS_NR];
2047 /** These are not exported so far */
2048 void cache_stats_init (struct cache_stats *cs, const char *name);
2051 * Client-side site. This represents particular client stack. "Global"
2052 * variables should (directly or indirectly) be added here to allow multiple
2053 * clients to co-exist in the single address space.
2056 struct lu_site cs_lu;
2058 * Statistical counters. Atomics do not scale, something better like
2059 * per-cpu counters is needed.
2061 * These are exported as /proc/fs/lustre/llite/.../site
2063 * When interpreting keep in mind that both sub-locks (and sub-pages)
2064 * and top-locks (and top-pages) are accounted here.
2066 struct cache_stats cs_pages;
2067 atomic_t cs_pages_state[CPS_NR];
2070 int cl_site_init(struct cl_site *s, struct cl_device *top);
2071 void cl_site_fini(struct cl_site *s);
2072 void cl_stack_fini(const struct lu_env *env, struct cl_device *cl);
2075 * Output client site statistical counters into a buffer. Suitable for
2076 * ll_rd_*()-style functions.
2078 int cl_site_stats_print(const struct cl_site *site, struct seq_file *m);
2083 * Type conversion and accessory functions.
2087 static inline struct cl_site *lu2cl_site(const struct lu_site *site)
2089 return container_of(site, struct cl_site, cs_lu);
2092 static inline int lu_device_is_cl(const struct lu_device *d)
2094 return d->ld_type->ldt_tags & LU_DEVICE_CL;
2097 static inline struct cl_device *lu2cl_dev(const struct lu_device *d)
2099 LASSERT(d == NULL || IS_ERR(d) || lu_device_is_cl(d));
2100 return container_of0(d, struct cl_device, cd_lu_dev);
2103 static inline struct lu_device *cl2lu_dev(struct cl_device *d)
2105 return &d->cd_lu_dev;
2108 static inline struct cl_object *lu2cl(const struct lu_object *o)
2110 LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->lo_dev));
2111 return container_of0(o, struct cl_object, co_lu);
2114 static inline const struct cl_object_conf *
2115 lu2cl_conf(const struct lu_object_conf *conf)
2117 return container_of0(conf, struct cl_object_conf, coc_lu);
2120 static inline struct cl_object *cl_object_next(const struct cl_object *obj)
2122 return obj ? lu2cl(lu_object_next(&obj->co_lu)) : NULL;
2125 static inline struct cl_object_header *luh2coh(const struct lu_object_header *h)
2127 return container_of0(h, struct cl_object_header, coh_lu);
2130 static inline struct cl_site *cl_object_site(const struct cl_object *obj)
2132 return lu2cl_site(obj->co_lu.lo_dev->ld_site);
2136 struct cl_object_header *cl_object_header(const struct cl_object *obj)
2138 return luh2coh(obj->co_lu.lo_header);
2141 static inline int cl_device_init(struct cl_device *d, struct lu_device_type *t)
2143 return lu_device_init(&d->cd_lu_dev, t);
2146 static inline void cl_device_fini(struct cl_device *d)
2148 lu_device_fini(&d->cd_lu_dev);
2151 void cl_page_slice_add(struct cl_page *page, struct cl_page_slice *slice,
2152 struct cl_object *obj, pgoff_t index,
2153 const struct cl_page_operations *ops);
2154 void cl_lock_slice_add(struct cl_lock *lock, struct cl_lock_slice *slice,
2155 struct cl_object *obj,
2156 const struct cl_lock_operations *ops);
2157 void cl_io_slice_add(struct cl_io *io, struct cl_io_slice *slice,
2158 struct cl_object *obj, const struct cl_io_operations *ops);
2159 void cl_req_slice_add(struct cl_req *req, struct cl_req_slice *slice,
2160 struct cl_device *dev,
2161 const struct cl_req_operations *ops);
2164 /** \defgroup cl_object cl_object
2166 struct cl_object *cl_object_top (struct cl_object *o);
2167 struct cl_object *cl_object_find(const struct lu_env *env, struct cl_device *cd,
2168 const struct lu_fid *fid,
2169 const struct cl_object_conf *c);
2171 int cl_object_header_init(struct cl_object_header *h);
2172 void cl_object_header_fini(struct cl_object_header *h);
2173 void cl_object_put (const struct lu_env *env, struct cl_object *o);
2174 void cl_object_get (struct cl_object *o);
2175 void cl_object_attr_lock (struct cl_object *o);
2176 void cl_object_attr_unlock(struct cl_object *o);
2177 int cl_object_attr_get (const struct lu_env *env, struct cl_object *obj,
2178 struct cl_attr *attr);
2179 int cl_object_attr_update(const struct lu_env *env, struct cl_object *obj,
2180 const struct cl_attr *attr, unsigned valid);
2181 int cl_object_glimpse (const struct lu_env *env, struct cl_object *obj,
2182 struct ost_lvb *lvb);
2183 int cl_conf_set (const struct lu_env *env, struct cl_object *obj,
2184 const struct cl_object_conf *conf);
2185 int cl_object_prune (const struct lu_env *env, struct cl_object *obj);
2186 void cl_object_kill (const struct lu_env *env, struct cl_object *obj);
2187 int cl_object_getstripe(const struct lu_env *env, struct cl_object *obj,
2188 struct lov_user_md __user *lum);
2189 int cl_object_find_cbdata(const struct lu_env *env, struct cl_object *obj,
2190 ldlm_iterator_t iter, void *data);
2193 * Returns true, iff \a o0 and \a o1 are slices of the same object.
2195 static inline int cl_object_same(struct cl_object *o0, struct cl_object *o1)
2197 return cl_object_header(o0) == cl_object_header(o1);
2200 static inline void cl_object_page_init(struct cl_object *clob, int size)
2202 clob->co_slice_off = cl_object_header(clob)->coh_page_bufsize;
2203 cl_object_header(clob)->coh_page_bufsize += cfs_size_round(size);
2204 WARN_ON(cl_object_header(clob)->coh_page_bufsize > 512);
2207 static inline void *cl_object_page_slice(struct cl_object *clob,
2208 struct cl_page *page)
2210 return (void *)((char *)page + clob->co_slice_off);
2214 * Return refcount of cl_object.
2216 static inline int cl_object_refc(struct cl_object *clob)
2218 struct lu_object_header *header = clob->co_lu.lo_header;
2219 return atomic_read(&header->loh_ref);
2224 /** \defgroup cl_page cl_page
2232 /* callback of cl_page_gang_lookup() */
2234 struct cl_page *cl_page_find (const struct lu_env *env,
2235 struct cl_object *obj,
2236 pgoff_t idx, struct page *vmpage,
2237 enum cl_page_type type);
2238 struct cl_page *cl_page_alloc (const struct lu_env *env,
2239 struct cl_object *o, pgoff_t ind,
2240 struct page *vmpage,
2241 enum cl_page_type type);
2242 void cl_page_get (struct cl_page *page);
2243 void cl_page_put (const struct lu_env *env,
2244 struct cl_page *page);
2245 void cl_page_print (const struct lu_env *env, void *cookie,
2246 lu_printer_t printer,
2247 const struct cl_page *pg);
2248 void cl_page_header_print(const struct lu_env *env, void *cookie,
2249 lu_printer_t printer,
2250 const struct cl_page *pg);
2251 struct cl_page *cl_vmpage_page (struct page *vmpage, struct cl_object *obj);
2252 struct cl_page *cl_page_top (struct cl_page *page);
2254 const struct cl_page_slice *cl_page_at(const struct cl_page *page,
2255 const struct lu_device_type *dtype);
2260 * Functions dealing with the ownership of page by io.
2264 int cl_page_own (const struct lu_env *env,
2265 struct cl_io *io, struct cl_page *page);
2266 int cl_page_own_try (const struct lu_env *env,
2267 struct cl_io *io, struct cl_page *page);
2268 void cl_page_assume (const struct lu_env *env,
2269 struct cl_io *io, struct cl_page *page);
2270 void cl_page_unassume (const struct lu_env *env,
2271 struct cl_io *io, struct cl_page *pg);
2272 void cl_page_disown (const struct lu_env *env,
2273 struct cl_io *io, struct cl_page *page);
2274 int cl_page_is_owned (const struct cl_page *pg, const struct cl_io *io);
2281 * Functions dealing with the preparation of a page for a transfer, and
2282 * tracking transfer state.
2285 int cl_page_prep (const struct lu_env *env, struct cl_io *io,
2286 struct cl_page *pg, enum cl_req_type crt);
2287 void cl_page_completion (const struct lu_env *env,
2288 struct cl_page *pg, enum cl_req_type crt, int ioret);
2289 int cl_page_make_ready (const struct lu_env *env, struct cl_page *pg,
2290 enum cl_req_type crt);
2291 int cl_page_cache_add (const struct lu_env *env, struct cl_io *io,
2292 struct cl_page *pg, enum cl_req_type crt);
2293 void cl_page_clip (const struct lu_env *env, struct cl_page *pg,
2295 int cl_page_cancel (const struct lu_env *env, struct cl_page *page);
2296 int cl_page_flush (const struct lu_env *env, struct cl_io *io,
2297 struct cl_page *pg);
2303 * \name helper routines
2304 * Functions to discard, delete and export a cl_page.
2307 void cl_page_discard(const struct lu_env *env, struct cl_io *io,
2308 struct cl_page *pg);
2309 void cl_page_delete(const struct lu_env *env, struct cl_page *pg);
2310 int cl_page_is_vmlocked(const struct lu_env *env,
2311 const struct cl_page *pg);
2312 void cl_page_export(const struct lu_env *env,
2313 struct cl_page *pg, int uptodate);
2314 int cl_page_is_under_lock(const struct lu_env *env, struct cl_io *io,
2315 struct cl_page *page, pgoff_t *max_index);
2316 loff_t cl_offset(const struct cl_object *obj, pgoff_t idx);
2317 pgoff_t cl_index(const struct cl_object *obj, loff_t offset);
2318 size_t cl_page_size(const struct cl_object *obj);
2320 void cl_lock_print(const struct lu_env *env, void *cookie,
2321 lu_printer_t printer, const struct cl_lock *lock);
2322 void cl_lock_descr_print(const struct lu_env *env, void *cookie,
2323 lu_printer_t printer,
2324 const struct cl_lock_descr *descr);
2328 * Data structure managing a client's cached pages. A count of
2329 * "unstable" pages is maintained, and an LRU of clean pages is
2330 * maintained. "unstable" pages are pages pinned by the ptlrpc
2331 * layer for recovery purposes.
2333 struct cl_client_cache {
2339 * # of threads are doing shrinking
2341 unsigned int ccc_lru_shrinkers;
2343 * # of LRU entries available
2345 atomic_long_t ccc_lru_left;
2347 * List of entities(OSCs) for this LRU cache
2349 struct list_head ccc_lru;
2351 * Max # of LRU entries
2353 unsigned long ccc_lru_max;
2355 * Lock to protect ccc_lru list
2357 spinlock_t ccc_lru_lock;
2359 * Set if unstable check is enabled
2361 unsigned int ccc_unstable_check:1;
2363 * # of unstable pages for this mount point
2365 atomic_long_t ccc_unstable_nr;
2367 * Waitq for awaiting unstable pages to reach zero.
2368 * Used at umounting time and signaled on BRW commit
2370 wait_queue_head_t ccc_unstable_waitq;
2375 /** \defgroup cl_lock cl_lock
2377 int cl_lock_request(const struct lu_env *env, struct cl_io *io,
2378 struct cl_lock *lock);
2379 int cl_lock_init(const struct lu_env *env, struct cl_lock *lock,
2380 const struct cl_io *io);
2381 void cl_lock_fini(const struct lu_env *env, struct cl_lock *lock);
2382 const struct cl_lock_slice *cl_lock_at(const struct cl_lock *lock,
2383 const struct lu_device_type *dtype);
2384 void cl_lock_release(const struct lu_env *env, struct cl_lock *lock);
2386 int cl_lock_enqueue(const struct lu_env *env, struct cl_io *io,
2387 struct cl_lock *lock, struct cl_sync_io *anchor);
2388 void cl_lock_cancel(const struct lu_env *env, struct cl_lock *lock);
2392 /** \defgroup cl_io cl_io
2395 int cl_io_init (const struct lu_env *env, struct cl_io *io,
2396 enum cl_io_type iot, struct cl_object *obj);
2397 int cl_io_sub_init (const struct lu_env *env, struct cl_io *io,
2398 enum cl_io_type iot, struct cl_object *obj);
2399 int cl_io_rw_init (const struct lu_env *env, struct cl_io *io,
2400 enum cl_io_type iot, loff_t pos, size_t count);
2401 int cl_io_loop (const struct lu_env *env, struct cl_io *io);
2403 void cl_io_fini (const struct lu_env *env, struct cl_io *io);
2404 int cl_io_iter_init (const struct lu_env *env, struct cl_io *io);
2405 void cl_io_iter_fini (const struct lu_env *env, struct cl_io *io);
2406 int cl_io_lock (const struct lu_env *env, struct cl_io *io);
2407 void cl_io_unlock (const struct lu_env *env, struct cl_io *io);
2408 int cl_io_start (const struct lu_env *env, struct cl_io *io);
2409 void cl_io_end (const struct lu_env *env, struct cl_io *io);
2410 int cl_io_lock_add (const struct lu_env *env, struct cl_io *io,
2411 struct cl_io_lock_link *link);
2412 int cl_io_lock_alloc_add(const struct lu_env *env, struct cl_io *io,
2413 struct cl_lock_descr *descr);
2414 int cl_io_read_page (const struct lu_env *env, struct cl_io *io,
2415 struct cl_page *page);
2416 int cl_io_submit_rw (const struct lu_env *env, struct cl_io *io,
2417 enum cl_req_type iot, struct cl_2queue *queue);
2418 int cl_io_submit_sync (const struct lu_env *env, struct cl_io *io,
2419 enum cl_req_type iot, struct cl_2queue *queue,
2421 int cl_io_commit_async (const struct lu_env *env, struct cl_io *io,
2422 struct cl_page_list *queue, int from, int to,
2424 void cl_io_rw_advance (const struct lu_env *env, struct cl_io *io,
2426 int cl_io_cancel (const struct lu_env *env, struct cl_io *io,
2427 struct cl_page_list *queue);
2428 int cl_io_is_going (const struct lu_env *env);
2431 * True, iff \a io is an O_APPEND write(2).
2433 static inline int cl_io_is_append(const struct cl_io *io)
2435 return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_append;
2438 static inline int cl_io_is_sync_write(const struct cl_io *io)
2440 return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_sync;
2443 static inline int cl_io_is_mkwrite(const struct cl_io *io)
2445 return io->ci_type == CIT_FAULT && io->u.ci_fault.ft_mkwrite;
2449 * True, iff \a io is a truncate(2).
2451 static inline int cl_io_is_trunc(const struct cl_io *io)
2453 return io->ci_type == CIT_SETATTR &&
2454 (io->u.ci_setattr.sa_valid & ATTR_SIZE);
2457 struct cl_io *cl_io_top(struct cl_io *io);
2459 void cl_io_print(const struct lu_env *env, void *cookie,
2460 lu_printer_t printer, const struct cl_io *io);
2462 #define CL_IO_SLICE_CLEAN(foo_io, base) \
2464 typeof(foo_io) __foo_io = (foo_io); \
2466 CLASSERT(offsetof(typeof(*__foo_io), base) == 0); \
2467 memset(&__foo_io->base + 1, 0, \
2468 (sizeof *__foo_io) - sizeof __foo_io->base); \
2473 /** \defgroup cl_page_list cl_page_list
2477 * Last page in the page list.
2479 static inline struct cl_page *cl_page_list_last(struct cl_page_list *plist)
2481 LASSERT(plist->pl_nr > 0);
2482 return list_entry(plist->pl_pages.prev, struct cl_page, cp_batch);
2485 static inline struct cl_page *cl_page_list_first(struct cl_page_list *plist)
2487 LASSERT(plist->pl_nr > 0);
2488 return list_entry(plist->pl_pages.next, struct cl_page, cp_batch);
2492 * Iterate over pages in a page list.
2494 #define cl_page_list_for_each(page, list) \
2495 list_for_each_entry((page), &(list)->pl_pages, cp_batch)
2498 * Iterate over pages in a page list, taking possible removals into account.
2500 #define cl_page_list_for_each_safe(page, temp, list) \
2501 list_for_each_entry_safe((page), (temp), &(list)->pl_pages, cp_batch)
2503 void cl_page_list_init (struct cl_page_list *plist);
2504 void cl_page_list_add (struct cl_page_list *plist, struct cl_page *page);
2505 void cl_page_list_move (struct cl_page_list *dst, struct cl_page_list *src,
2506 struct cl_page *page);
2507 void cl_page_list_move_head(struct cl_page_list *dst, struct cl_page_list *src,
2508 struct cl_page *page);
2509 void cl_page_list_splice (struct cl_page_list *list,
2510 struct cl_page_list *head);
2511 void cl_page_list_del (const struct lu_env *env,
2512 struct cl_page_list *plist, struct cl_page *page);
2513 void cl_page_list_disown (const struct lu_env *env,
2514 struct cl_io *io, struct cl_page_list *plist);
2515 int cl_page_list_own (const struct lu_env *env,
2516 struct cl_io *io, struct cl_page_list *plist);
2517 void cl_page_list_assume (const struct lu_env *env,
2518 struct cl_io *io, struct cl_page_list *plist);
2519 void cl_page_list_discard(const struct lu_env *env,
2520 struct cl_io *io, struct cl_page_list *plist);
2521 void cl_page_list_fini (const struct lu_env *env, struct cl_page_list *plist);
2523 void cl_2queue_init (struct cl_2queue *queue);
2524 void cl_2queue_add (struct cl_2queue *queue, struct cl_page *page);
2525 void cl_2queue_disown (const struct lu_env *env,
2526 struct cl_io *io, struct cl_2queue *queue);
2527 void cl_2queue_assume (const struct lu_env *env,
2528 struct cl_io *io, struct cl_2queue *queue);
2529 void cl_2queue_discard (const struct lu_env *env,
2530 struct cl_io *io, struct cl_2queue *queue);
2531 void cl_2queue_fini (const struct lu_env *env, struct cl_2queue *queue);
2532 void cl_2queue_init_page(struct cl_2queue *queue, struct cl_page *page);
2534 /** @} cl_page_list */
2536 /** \defgroup cl_req cl_req
2538 struct cl_req *cl_req_alloc(const struct lu_env *env, struct cl_page *page,
2539 enum cl_req_type crt, int nr_objects);
2541 void cl_req_page_add (const struct lu_env *env, struct cl_req *req,
2542 struct cl_page *page);
2543 void cl_req_page_done (const struct lu_env *env, struct cl_page *page);
2544 int cl_req_prep (const struct lu_env *env, struct cl_req *req);
2545 void cl_req_attr_set(const struct lu_env *env, struct cl_req *req,
2546 struct cl_req_attr *attr, u64 flags);
2547 void cl_req_completion(const struct lu_env *env, struct cl_req *req, int ioret);
2549 /** \defgroup cl_sync_io cl_sync_io
2553 * Anchor for synchronous transfer. This is allocated on a stack by thread
2554 * doing synchronous transfer, and a pointer to this structure is set up in
2555 * every page submitted for transfer. Transfer completion routine updates
2556 * anchor and wakes up waiting thread when transfer is complete.
2559 /** number of pages yet to be transferred. */
2560 atomic_t csi_sync_nr;
2563 /** barrier of destroy this structure */
2564 atomic_t csi_barrier;
2565 /** completion to be signaled when transfer is complete. */
2566 wait_queue_head_t csi_waitq;
2567 /** callback to invoke when this IO is finished */
2568 void (*csi_end_io)(const struct lu_env *,
2569 struct cl_sync_io *);
2572 void cl_sync_io_init(struct cl_sync_io *anchor, int nr,
2573 void (*end)(const struct lu_env *, struct cl_sync_io *));
2574 int cl_sync_io_wait(const struct lu_env *env, struct cl_sync_io *anchor,
2576 void cl_sync_io_note(const struct lu_env *env, struct cl_sync_io *anchor,
2578 void cl_sync_io_end(const struct lu_env *env, struct cl_sync_io *anchor);
2580 /** @} cl_sync_io */
2584 /** \defgroup cl_env cl_env
2586 * lu_env handling for a client.
2588 * lu_env is an environment within which lustre code executes. Its major part
2589 * is lu_context---a fast memory allocation mechanism that is used to conserve
2590 * precious kernel stack space. Originally lu_env was designed for a server,
2593 * - there is a (mostly) fixed number of threads, and
2595 * - call chains have no non-lustre portions inserted between lustre code.
2597 * On a client both these assumtpion fails, because every user thread can
2598 * potentially execute lustre code as part of a system call, and lustre calls
2599 * into VFS or MM that call back into lustre.
2601 * To deal with that, cl_env wrapper functions implement the following
2604 * - allocation and destruction of environment is amortized by caching no
2605 * longer used environments instead of destroying them;
2607 * - there is a notion of "current" environment, attached to the kernel
2608 * data structure representing current thread Top-level lustre code
2609 * allocates an environment and makes it current, then calls into
2610 * non-lustre code, that in turn calls lustre back. Low-level lustre
2611 * code thus called can fetch environment created by the top-level code
2612 * and reuse it, avoiding additional environment allocation.
2613 * Right now, three interfaces can attach the cl_env to running thread:
2616 * - cl_env_reexit(cl_env_reenter had to be called priorly)
2618 * \see lu_env, lu_context, lu_context_key
2621 struct cl_env_nest {
2626 struct lu_env *cl_env_peek (int *refcheck);
2627 struct lu_env *cl_env_get (int *refcheck);
2628 struct lu_env *cl_env_alloc (int *refcheck, __u32 tags);
2629 struct lu_env *cl_env_nested_get (struct cl_env_nest *nest);
2630 void cl_env_put (struct lu_env *env, int *refcheck);
2631 void cl_env_nested_put (struct cl_env_nest *nest, struct lu_env *env);
2632 void *cl_env_reenter (void);
2633 void cl_env_reexit (void *cookie);
2634 void cl_env_implant (struct lu_env *env, int *refcheck);
2635 void cl_env_unplant (struct lu_env *env, int *refcheck);
2636 unsigned cl_env_cache_purge(unsigned nr);
2637 struct lu_env *cl_env_percpu_get (void);
2638 void cl_env_percpu_put (struct lu_env *env);
2645 void cl_attr2lvb(struct ost_lvb *lvb, const struct cl_attr *attr);
2646 void cl_lvb2attr(struct cl_attr *attr, const struct ost_lvb *lvb);
2648 struct cl_device *cl_type_setup(const struct lu_env *env, struct lu_site *site,
2649 struct lu_device_type *ldt,
2650 struct lu_device *next);
2653 int cl_global_init(void);
2654 void cl_global_fini(void);
2656 #endif /* _LINUX_CL_OBJECT_H */