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23 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
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26 * Copyright (c) 2011, 2017, Intel Corporation.
29 * This file is part of Lustre, http://www.lustre.org/
30 * Lustre is a trademark of Sun Microsystems, Inc.
32 #ifndef _LUSTRE_CL_OBJECT_H
33 #define _LUSTRE_CL_OBJECT_H
35 /** \defgroup clio clio
37 * Client objects implement io operations and cache pages.
39 * Examples: lov and osc are implementations of cl interface.
41 * Big Theory Statement.
45 * Client implementation is based on the following data-types:
51 * - cl_lock represents an extent lock on an object.
53 * - cl_io represents high-level i/o activity such as whole read/write
54 * system call, or write-out of pages from under the lock being
55 * canceled. cl_io has sub-ios that can be stopped and resumed
56 * independently, thus achieving high degree of transfer
57 * parallelism. Single cl_io can be advanced forward by
58 * the multiple threads (although in the most usual case of
59 * read/write system call it is associated with the single user
60 * thread, that issued the system call).
64 * - to avoid confusion high-level I/O operation like read or write system
65 * call is referred to as "an io", whereas low-level I/O operation, like
66 * RPC, is referred to as "a transfer"
68 * - "generic code" means generic (not file system specific) code in the
69 * hosting environment. "cl-code" means code (mostly in cl_*.c files) that
70 * is not layer specific.
76 * - cl_object_header::coh_page_guard
79 * See the top comment in cl_object.c for the description of overall locking and
80 * reference-counting design.
82 * See comments below for the description of i/o, page, and dlm-locking
89 * super-class definitions.
91 #include <linux/aio.h>
94 #include <libcfs/libcfs.h>
95 #include <lu_object.h>
96 #include <linux/atomic.h>
97 #include <linux/mutex.h>
98 #include <linux/radix-tree.h>
99 #include <linux/spinlock.h>
100 #include <linux/wait.h>
101 #include <linux/pagevec.h>
102 #include <lustre_dlm.h>
112 struct cl_page_slice;
114 struct cl_lock_slice;
116 struct cl_lock_operations;
117 struct cl_page_operations;
125 * Device in the client stack.
127 * \see vvp_device, lov_device, lovsub_device, osc_device
131 struct lu_device cd_lu_dev;
134 /** \addtogroup cl_object cl_object
137 * "Data attributes" of cl_object. Data attributes can be updated
138 * independently for a sub-object, and top-object's attributes are calculated
139 * from sub-objects' ones.
142 /** Object size, in bytes */
145 * Known minimal size, in bytes.
147 * This is only valid when at least one DLM lock is held.
150 /** Modification time. Measured in seconds since epoch. */
152 /** Access time. Measured in seconds since epoch. */
154 /** Change time. Measured in seconds since epoch. */
157 * Blocks allocated to this cl_object on the server file system.
159 * \todo XXX An interface for block size is needed.
163 * User identifier for quota purposes.
167 * Group identifier for quota purposes.
171 /* nlink of the directory */
174 /* Project identifier for quota purpose. */
179 * Fields in cl_attr that are being set.
194 * Sub-class of lu_object with methods common for objects on the client
197 * cl_object: represents a regular file system object, both a file and a
198 * stripe. cl_object is based on lu_object: it is identified by a fid,
199 * layered, cached, hashed, and lrued. Important distinction with the server
200 * side, where md_object and dt_object are used, is that cl_object "fans out"
201 * at the lov/sns level: depending on the file layout, single file is
202 * represented as a set of "sub-objects" (stripes). At the implementation
203 * level, struct lov_object contains an array of cl_objects. Each sub-object
204 * is a full-fledged cl_object, having its fid, living in the lru and hash
207 * This leads to the next important difference with the server side: on the
208 * client, it's quite usual to have objects with the different sequence of
209 * layers. For example, typical top-object is composed of the following
215 * whereas its sub-objects are composed of
220 * layers. Here "lovsub" is a mostly dummy layer, whose purpose is to keep
221 * track of the object-subobject relationship.
223 * Sub-objects are not cached independently: when top-object is about to
224 * be discarded from the memory, all its sub-objects are torn-down and
227 * \see vvp_object, lov_object, lovsub_object, osc_object
231 struct lu_object co_lu;
232 /** per-object-layer operations */
233 const struct cl_object_operations *co_ops;
234 /** offset of page slice in cl_page buffer */
239 * Description of the client object configuration. This is used for the
240 * creation of a new client object that is identified by a more state than
243 struct cl_object_conf {
245 struct lu_object_conf coc_lu;
248 * Object layout. This is consumed by lov.
250 struct lu_buf coc_layout;
252 * Description of particular stripe location in the
253 * cluster. This is consumed by osc.
255 struct lov_oinfo *coc_oinfo;
258 * VFS inode. This is consumed by vvp.
260 struct inode *coc_inode;
262 * Layout lock handle.
264 struct ldlm_lock *coc_lock;
266 * Operation to handle layout, OBJECT_CONF_XYZ.
272 /** configure layout, set up a new stripe, must be called while
273 * holding layout lock. */
275 /** invalidate the current stripe configuration due to losing
277 OBJECT_CONF_INVALIDATE = 1,
278 /** wait for old layout to go away so that new layout can be
284 CL_LAYOUT_GEN_NONE = (u32)-2, /* layout lock was cancelled */
285 CL_LAYOUT_GEN_EMPTY = (u32)-1, /* for empty layout */
289 /** the buffer to return the layout in lov_mds_md format. */
290 struct lu_buf cl_buf;
291 /** size of layout in lov_mds_md format. */
293 /** size of DoM component if exists or zero otherwise */
294 u64 cl_dom_comp_size;
295 /** Layout generation. */
297 /** whether layout is a composite one */
298 bool cl_is_composite;
299 /** Whether layout is a HSM released one */
304 * Operations implemented for each cl object layer.
306 * \see vvp_ops, lov_ops, lovsub_ops, osc_ops
308 struct cl_object_operations {
310 * Initialize page slice for this layer. Called top-to-bottom through
311 * every object layer when a new cl_page is instantiated. Layer
312 * keeping private per-page data, or requiring its own page operations
313 * vector should allocate these data here, and attach then to the page
314 * by calling cl_page_slice_add(). \a vmpage is locked (in the VM
317 * \retval NULL success.
319 * \retval ERR_PTR(errno) failure code.
321 * \retval valid-pointer pointer to already existing referenced page
322 * to be used instead of newly created.
324 int (*coo_page_init)(const struct lu_env *env, struct cl_object *obj,
325 struct cl_page *page, pgoff_t index);
327 * Initialize lock slice for this layer. Called top-to-bottom through
328 * every object layer when a new cl_lock is instantiated. Layer
329 * keeping private per-lock data, or requiring its own lock operations
330 * vector should allocate these data here, and attach then to the lock
331 * by calling cl_lock_slice_add(). Mandatory.
333 int (*coo_lock_init)(const struct lu_env *env,
334 struct cl_object *obj, struct cl_lock *lock,
335 const struct cl_io *io);
337 * Initialize io state for a given layer.
339 * called top-to-bottom once per io existence to initialize io
340 * state. If layer wants to keep some state for this type of io, it
341 * has to embed struct cl_io_slice in lu_env::le_ses, and register
342 * slice with cl_io_slice_add(). It is guaranteed that all threads
343 * participating in this io share the same session.
345 int (*coo_io_init)(const struct lu_env *env,
346 struct cl_object *obj, struct cl_io *io);
348 * Fill portion of \a attr that this layer controls. This method is
349 * called top-to-bottom through all object layers.
351 * \pre cl_object_header::coh_attr_guard of the top-object is locked.
353 * \return 0: to continue
354 * \return +ve: to stop iterating through layers (but 0 is returned
355 * from enclosing cl_object_attr_get())
356 * \return -ve: to signal error
358 int (*coo_attr_get)(const struct lu_env *env, struct cl_object *obj,
359 struct cl_attr *attr);
363 * \a valid is a bitmask composed from enum #cl_attr_valid, and
364 * indicating what attributes are to be set.
366 * \pre cl_object_header::coh_attr_guard of the top-object is locked.
368 * \return the same convention as for
369 * cl_object_operations::coo_attr_get() is used.
371 int (*coo_attr_update)(const struct lu_env *env, struct cl_object *obj,
372 const struct cl_attr *attr, unsigned valid);
374 * Update object configuration. Called top-to-bottom to modify object
377 * XXX error conditions and handling.
379 int (*coo_conf_set)(const struct lu_env *env, struct cl_object *obj,
380 const struct cl_object_conf *conf);
382 * Glimpse ast. Executed when glimpse ast arrives for a lock on this
383 * object. Layers are supposed to fill parts of \a lvb that will be
384 * shipped to the glimpse originator as a glimpse result.
386 * \see vvp_object_glimpse(), lovsub_object_glimpse(),
387 * \see osc_object_glimpse()
389 int (*coo_glimpse)(const struct lu_env *env,
390 const struct cl_object *obj, struct ost_lvb *lvb);
392 * Object prune method. Called when the layout is going to change on
393 * this object, therefore each layer has to clean up their cache,
394 * mainly pages and locks.
396 int (*coo_prune)(const struct lu_env *env, struct cl_object *obj);
398 * Object getstripe method.
400 int (*coo_getstripe)(const struct lu_env *env, struct cl_object *obj,
401 struct lov_user_md __user *lum, size_t size);
403 * Get FIEMAP mapping from the object.
405 int (*coo_fiemap)(const struct lu_env *env, struct cl_object *obj,
406 struct ll_fiemap_info_key *fmkey,
407 struct fiemap *fiemap, size_t *buflen);
409 * Get layout and generation of the object.
411 int (*coo_layout_get)(const struct lu_env *env, struct cl_object *obj,
412 struct cl_layout *layout);
414 * Get maximum size of the object.
416 loff_t (*coo_maxbytes)(struct cl_object *obj);
418 * Set request attributes.
420 void (*coo_req_attr_set)(const struct lu_env *env,
421 struct cl_object *obj,
422 struct cl_req_attr *attr);
426 * Extended header for client object.
428 struct cl_object_header {
429 /** Standard lu_object_header. cl_object::co_lu::lo_header points
431 struct lu_object_header coh_lu;
434 * Parent object. It is assumed that an object has a well-defined
435 * parent, but not a well-defined child (there may be multiple
436 * sub-objects, for the same top-object). cl_object_header::coh_parent
437 * field allows certain code to be written generically, without
438 * limiting possible cl_object layouts unduly.
440 struct cl_object_header *coh_parent;
442 * Protects consistency between cl_attr of parent object and
443 * attributes of sub-objects, that the former is calculated ("merged")
446 * \todo XXX this can be read/write lock if needed.
448 spinlock_t coh_attr_guard;
450 * Size of cl_page + page slices
452 unsigned short coh_page_bufsize;
454 * Number of objects above this one: 0 for a top-object, 1 for its
457 unsigned char coh_nesting;
461 * Helper macro: iterate over all layers of the object \a obj, assigning every
462 * layer top-to-bottom to \a slice.
464 #define cl_object_for_each(slice, obj) \
465 list_for_each_entry((slice), \
466 &(obj)->co_lu.lo_header->loh_layers,\
470 * Helper macro: iterate over all layers of the object \a obj, assigning every
471 * layer bottom-to-top to \a slice.
473 #define cl_object_for_each_reverse(slice, obj) \
474 list_for_each_entry_reverse((slice), \
475 &(obj)->co_lu.lo_header->loh_layers,\
480 #define CL_PAGE_EOF ((pgoff_t)~0ull)
482 /** \addtogroup cl_page cl_page
486 * Layered client page.
488 * cl_page: represents a portion of a file, cached in the memory. All pages
489 * of the given file are of the same size, and are kept in the radix tree
490 * hanging off the cl_object. cl_page doesn't fan out, but as sub-objects
491 * of the top-level file object are first class cl_objects, they have their
492 * own radix trees of pages and hence page is implemented as a sequence of
493 * struct cl_pages's, linked into double-linked list through
494 * cl_page::cp_parent and cl_page::cp_child pointers, each residing in the
495 * corresponding radix tree at the corresponding logical offset.
497 * cl_page is associated with VM page of the hosting environment (struct
498 * page in Linux kernel, for example), struct page. It is assumed, that this
499 * association is implemented by one of cl_page layers (top layer in the
500 * current design) that
502 * - intercepts per-VM-page call-backs made by the environment (e.g.,
505 * - translates state (page flag bits) and locking between lustre and
508 * The association between cl_page and struct page is immutable and
509 * established when cl_page is created.
511 * cl_page can be "owned" by a particular cl_io (see below), guaranteeing
512 * this io an exclusive access to this page w.r.t. other io attempts and
513 * various events changing page state (such as transfer completion, or
514 * eviction of the page from the memory). Note, that in general cl_io
515 * cannot be identified with a particular thread, and page ownership is not
516 * exactly equal to the current thread holding a lock on the page. Layer
517 * implementing association between cl_page and struct page has to implement
518 * ownership on top of available synchronization mechanisms.
520 * While lustre client maintains the notion of an page ownership by io,
521 * hosting MM/VM usually has its own page concurrency control
522 * mechanisms. For example, in Linux, page access is synchronized by the
523 * per-page PG_locked bit-lock, and generic kernel code (generic_file_*())
524 * takes care to acquire and release such locks as necessary around the
525 * calls to the file system methods (->readpage(), ->prepare_write(),
526 * ->commit_write(), etc.). This leads to the situation when there are two
527 * different ways to own a page in the client:
529 * - client code explicitly and voluntary owns the page (cl_page_own());
531 * - VM locks a page and then calls the client, that has "to assume"
532 * the ownership from the VM (cl_page_assume()).
534 * Dual methods to release ownership are cl_page_disown() and
535 * cl_page_unassume().
537 * cl_page is reference counted (cl_page::cp_ref). When reference counter
538 * drops to 0, the page is returned to the cache, unless it is in
539 * cl_page_state::CPS_FREEING state, in which case it is immediately
542 * The general logic guaranteeing the absence of "existential races" for
543 * pages is the following:
545 * - there are fixed known ways for a thread to obtain a new reference
548 * - by doing a lookup in the cl_object radix tree, protected by the
551 * - by starting from VM-locked struct page and following some
552 * hosting environment method (e.g., following ->private pointer in
553 * the case of Linux kernel), see cl_vmpage_page();
555 * - when the page enters cl_page_state::CPS_FREEING state, all these
556 * ways are severed with the proper synchronization
557 * (cl_page_delete());
559 * - entry into cl_page_state::CPS_FREEING is serialized by the VM page
562 * - no new references to the page in cl_page_state::CPS_FREEING state
563 * are allowed (checked in cl_page_get()).
565 * Together this guarantees that when last reference to a
566 * cl_page_state::CPS_FREEING page is released, it is safe to destroy the
567 * page, as neither references to it can be acquired at that point, nor
570 * cl_page is a state machine. States are enumerated in enum
571 * cl_page_state. Possible state transitions are enumerated in
572 * cl_page_state_set(). State transition process (i.e., actual changing of
573 * cl_page::cp_state field) is protected by the lock on the underlying VM
576 * Linux Kernel implementation.
578 * Binding between cl_page and struct page (which is a typedef for
579 * struct page) is implemented in the vvp layer. cl_page is attached to the
580 * ->private pointer of the struct page, together with the setting of
581 * PG_private bit in page->flags, and acquiring additional reference on the
582 * struct page (much like struct buffer_head, or any similar file system
583 * private data structures).
585 * PG_locked lock is used to implement both ownership and transfer
586 * synchronization, that is, page is VM-locked in CPS_{OWNED,PAGE{IN,OUT}}
587 * states. No additional references are acquired for the duration of the
590 * \warning *THIS IS NOT* the behavior expected by the Linux kernel, where
591 * write-out is "protected" by the special PG_writeback bit.
595 * States of cl_page. cl_page.c assumes particular order here.
597 * The page state machine is rather crude, as it doesn't recognize finer page
598 * states like "dirty" or "up to date". This is because such states are not
599 * always well defined for the whole stack (see, for example, the
600 * implementation of the read-ahead, that hides page up-to-dateness to track
601 * cache hits accurately). Such sub-states are maintained by the layers that
602 * are interested in them.
606 * Page is in the cache, un-owned. Page leaves cached state in the
609 * - [cl_page_state::CPS_OWNED] io comes across the page and
612 * - [cl_page_state::CPS_PAGEOUT] page is dirty, the
613 * req-formation engine decides that it wants to include this page
614 * into an RPC being constructed, and yanks it from the cache;
616 * - [cl_page_state::CPS_FREEING] VM callback is executed to
617 * evict the page form the memory;
619 * \invariant cl_page::cp_owner == NULL && cl_page::cp_req == NULL
623 * Page is exclusively owned by some cl_io. Page may end up in this
624 * state as a result of
626 * - io creating new page and immediately owning it;
628 * - [cl_page_state::CPS_CACHED] io finding existing cached page
631 * - [cl_page_state::CPS_OWNED] io finding existing owned page
632 * and waiting for owner to release the page;
634 * Page leaves owned state in the following cases:
636 * - [cl_page_state::CPS_CACHED] io decides to leave the page in
637 * the cache, doing nothing;
639 * - [cl_page_state::CPS_PAGEIN] io starts read transfer for
642 * - [cl_page_state::CPS_PAGEOUT] io starts immediate write
643 * transfer for this page;
645 * - [cl_page_state::CPS_FREEING] io decides to destroy this
646 * page (e.g., as part of truncate or extent lock cancellation).
648 * \invariant cl_page::cp_owner != NULL && cl_page::cp_req == NULL
652 * Page is being written out, as a part of a transfer. This state is
653 * entered when req-formation logic decided that it wants this page to
654 * be sent through the wire _now_. Specifically, it means that once
655 * this state is achieved, transfer completion handler (with either
656 * success or failure indication) is guaranteed to be executed against
657 * this page independently of any locks and any scheduling decisions
658 * made by the hosting environment (that effectively means that the
659 * page is never put into cl_page_state::CPS_PAGEOUT state "in
660 * advance". This property is mentioned, because it is important when
661 * reasoning about possible dead-locks in the system). The page can
662 * enter this state as a result of
664 * - [cl_page_state::CPS_OWNED] an io requesting an immediate
665 * write-out of this page, or
667 * - [cl_page_state::CPS_CACHED] req-forming engine deciding
668 * that it has enough dirty pages cached to issue a "good"
671 * The page leaves cl_page_state::CPS_PAGEOUT state when the transfer
672 * is completed---it is moved into cl_page_state::CPS_CACHED state.
674 * Underlying VM page is locked for the duration of transfer.
676 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL
680 * Page is being read in, as a part of a transfer. This is quite
681 * similar to the cl_page_state::CPS_PAGEOUT state, except that
682 * read-in is always "immediate"---there is no such thing a sudden
683 * construction of read request from cached, presumably not up to date,
686 * Underlying VM page is locked for the duration of transfer.
688 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL
692 * Page is being destroyed. This state is entered when client decides
693 * that page has to be deleted from its host object, as, e.g., a part
696 * Once this state is reached, there is no way to escape it.
698 * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req == NULL
705 /** Host page, the page is from the host inode which the cl_page
709 /** Transient page, the transient cl_page is used to bind a cl_page
710 * to vmpage which is not belonging to the same object of cl_page.
711 * it is used in DirectIO and lockless IO. */
716 * Fields are protected by the lock on struct page, except for atomics and
719 * \invariant Data type invariants are in cl_page_invariant(). Basically:
720 * cl_page::cp_parent and cl_page::cp_child are a well-formed double-linked
721 * list, consistent with the parent/child pointers in the cl_page::cp_obj and
722 * cl_page::cp_owner (when set).
725 /** Reference counter. */
727 /** An object this page is a part of. Immutable after creation. */
728 struct cl_object *cp_obj;
730 struct page *cp_vmpage;
731 /** Linkage of pages within group. Pages must be owned */
732 struct list_head cp_batch;
733 /** List of slices. Immutable after creation. */
734 struct list_head cp_layers;
736 * Page state. This field is const to avoid accidental update, it is
737 * modified only internally within cl_page.c. Protected by a VM lock.
739 const enum cl_page_state cp_state;
741 * Page type. Only CPT_TRANSIENT is used so far. Immutable after
744 enum cl_page_type cp_type;
747 * Owning IO in cl_page_state::CPS_OWNED state. Sub-page can be owned
748 * by sub-io. Protected by a VM lock.
750 struct cl_io *cp_owner;
751 /** List of references to this page, for debugging. */
752 struct lu_ref cp_reference;
753 /** Link to an object, for debugging. */
754 struct lu_ref_link cp_obj_ref;
755 /** Link to a queue, for debugging. */
756 struct lu_ref_link cp_queue_ref;
757 /** Assigned if doing a sync_io */
758 struct cl_sync_io *cp_sync_io;
762 * Per-layer part of cl_page.
764 * \see vvp_page, lov_page, osc_page
766 struct cl_page_slice {
767 struct cl_page *cpl_page;
770 * Object slice corresponding to this page slice. Immutable after
773 struct cl_object *cpl_obj;
774 const struct cl_page_operations *cpl_ops;
775 /** Linkage into cl_page::cp_layers. Immutable after creation. */
776 struct list_head cpl_linkage;
780 * Lock mode. For the client extent locks.
792 * 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);
874 * Update file attributes when all we have is this page. Used for tiny
875 * writes to update attributes when we don't have a full cl_io.
877 void (*cpo_page_touch)(const struct lu_env *env,
878 const struct cl_page_slice *slice, size_t to);
884 * Called when page is truncated from the object. Optional.
886 * \see cl_page_discard()
887 * \see vvp_page_discard(), osc_page_discard()
889 void (*cpo_discard)(const struct lu_env *env,
890 const struct cl_page_slice *slice,
893 * Called when page is removed from the cache, and is about to being
894 * destroyed. Optional.
896 * \see cl_page_delete()
897 * \see vvp_page_delete(), osc_page_delete()
899 void (*cpo_delete)(const struct lu_env *env,
900 const struct cl_page_slice *slice);
901 /** Destructor. Frees resources and slice itself. */
902 void (*cpo_fini)(const struct lu_env *env,
903 struct cl_page_slice *slice,
904 struct pagevec *pvec);
906 * Optional debugging helper. Prints given page slice.
908 * \see cl_page_print()
910 int (*cpo_print)(const struct lu_env *env,
911 const struct cl_page_slice *slice,
912 void *cookie, lu_printer_t p);
921 * Request type dependent vector of operations.
923 * Transfer operations depend on transfer mode (cl_req_type). To avoid
924 * passing transfer mode to each and every of these methods, and to
925 * avoid branching on request type inside of the methods, separate
926 * methods for cl_req_type:CRT_READ and cl_req_type:CRT_WRITE are
927 * provided. That is, method invocation usually looks like
929 * slice->cp_ops.io[req->crq_type].cpo_method(env, slice, ...);
933 * Called when a page is submitted for a transfer as a part of
936 * \return 0 : page is eligible for submission;
937 * \return -EALREADY : skip this page;
938 * \return -ve : error.
940 * \see cl_page_prep()
942 int (*cpo_prep)(const struct lu_env *env,
943 const struct cl_page_slice *slice,
946 * Completion handler. This is guaranteed to be eventually
947 * fired after cl_page_operations::cpo_prep() or
948 * cl_page_operations::cpo_make_ready() call.
950 * This method can be called in a non-blocking context. It is
951 * guaranteed however, that the page involved and its object
952 * are pinned in memory (and, hence, calling cl_page_put() is
955 * \see cl_page_completion()
957 void (*cpo_completion)(const struct lu_env *env,
958 const struct cl_page_slice *slice,
961 * Called when cached page is about to be added to the
962 * ptlrpc request as a part of req formation.
964 * \return 0 : proceed with this page;
965 * \return -EAGAIN : skip this page;
966 * \return -ve : error.
968 * \see cl_page_make_ready()
970 int (*cpo_make_ready)(const struct lu_env *env,
971 const struct cl_page_slice *slice);
974 * Tell transfer engine that only [to, from] part of a page should be
977 * This is used for immediate transfers.
979 * \todo XXX this is not very good interface. It would be much better
980 * if all transfer parameters were supplied as arguments to
981 * cl_io_operations::cio_submit() call, but it is not clear how to do
982 * this for page queues.
984 * \see cl_page_clip()
986 void (*cpo_clip)(const struct lu_env *env,
987 const struct cl_page_slice *slice,
990 * \pre the page was queued for transferring.
991 * \post page is removed from client's pending list, or -EBUSY
992 * is returned if it has already been in transferring.
994 * This is one of seldom page operation which is:
995 * 0. called from top level;
996 * 1. don't have vmpage locked;
997 * 2. every layer should synchronize execution of its ->cpo_cancel()
998 * with completion handlers. Osc uses client obd lock for this
999 * purpose. Based on there is no vvp_page_cancel and
1000 * lov_page_cancel(), cpo_cancel is defacto protected by client lock.
1002 * \see osc_page_cancel().
1004 int (*cpo_cancel)(const struct lu_env *env,
1005 const struct cl_page_slice *slice);
1007 * Write out a page by kernel. This is only called by ll_writepage
1010 * \see cl_page_flush()
1012 int (*cpo_flush)(const struct lu_env *env,
1013 const struct cl_page_slice *slice,
1019 * Helper macro, dumping detailed information about \a page into a log.
1021 #define CL_PAGE_DEBUG(mask, env, page, format, ...) \
1023 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1024 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1025 cl_page_print(env, &msgdata, lu_cdebug_printer, page); \
1026 CDEBUG(mask, format , ## __VA_ARGS__); \
1031 * Helper macro, dumping shorter information about \a page into a log.
1033 #define CL_PAGE_HEADER(mask, env, page, format, ...) \
1035 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1036 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1037 cl_page_header_print(env, &msgdata, lu_cdebug_printer, page); \
1038 CDEBUG(mask, format , ## __VA_ARGS__); \
1042 static inline struct page *cl_page_vmpage(const struct cl_page *page)
1044 LASSERT(page->cp_vmpage != NULL);
1045 return page->cp_vmpage;
1049 * Check if a cl_page is in use.
1051 * Client cache holds a refcount, this refcount will be dropped when
1052 * the page is taken out of cache, see vvp_page_delete().
1054 static inline bool __page_in_use(const struct cl_page *page, int refc)
1056 return (atomic_read(&page->cp_ref) > refc + 1);
1060 * Caller itself holds a refcount of cl_page.
1062 #define cl_page_in_use(pg) __page_in_use(pg, 1)
1064 * Caller doesn't hold a refcount.
1066 #define cl_page_in_use_noref(pg) __page_in_use(pg, 0)
1070 /** \addtogroup cl_lock cl_lock
1074 * Extent locking on the client.
1078 * The locking model of the new client code is built around
1082 * data-type representing an extent lock on a regular file. cl_lock is a
1083 * layered object (much like cl_object and cl_page), it consists of a header
1084 * (struct cl_lock) and a list of layers (struct cl_lock_slice), linked to
1085 * cl_lock::cll_layers list through cl_lock_slice::cls_linkage.
1087 * Typical cl_lock consists of one layer:
1089 * - lov_lock (lov specific data).
1091 * lov_lock contains an array of sub-locks. Each of these sub-locks is a
1092 * normal cl_lock: it has a header (struct cl_lock) and a list of layers:
1096 * Each sub-lock is associated with a cl_object (representing stripe
1097 * sub-object or the file to which top-level cl_lock is associated to), and is
1098 * linked into that cl_object::coh_locks. In this respect cl_lock is similar to
1099 * cl_object (that at lov layer also fans out into multiple sub-objects), and
1100 * is different from cl_page, that doesn't fan out (there is usually exactly
1101 * one osc_page for every vvp_page). We shall call vvp-lov portion of the lock
1102 * a "top-lock" and its lovsub-osc portion a "sub-lock".
1106 * cl_lock is a cacheless data container for the requirements of locks to
1107 * complete the IO. cl_lock is created before I/O starts and destroyed when the
1110 * cl_lock depends on LDLM lock to fulfill lock semantics. LDLM lock is attached
1111 * to cl_lock at OSC layer. LDLM lock is still cacheable.
1113 * INTERFACE AND USAGE
1115 * Two major methods are supported for cl_lock: clo_enqueue and clo_cancel. A
1116 * cl_lock is enqueued by cl_lock_request(), which will call clo_enqueue()
1117 * methods for each layer to enqueue the lock. At the LOV layer, if a cl_lock
1118 * consists of multiple sub cl_locks, each sub locks will be enqueued
1119 * correspondingly. At OSC layer, the lock enqueue request will tend to reuse
1120 * cached LDLM lock; otherwise a new LDLM lock will have to be requested from
1123 * cl_lock_cancel() must be called to release a cl_lock after use. clo_cancel()
1124 * method will be called for each layer to release the resource held by this
1125 * lock. At OSC layer, the reference count of LDLM lock, which is held at
1126 * clo_enqueue time, is released.
1128 * LDLM lock can only be canceled if there is no cl_lock using it.
1130 * Overall process of the locking during IO operation is as following:
1132 * - once parameters for IO are setup in cl_io, cl_io_operations::cio_lock()
1133 * is called on each layer. Responsibility of this method is to add locks,
1134 * needed by a given layer into cl_io.ci_lockset.
1136 * - once locks for all layers were collected, they are sorted to avoid
1137 * dead-locks (cl_io_locks_sort()), and enqueued.
1139 * - when all locks are acquired, IO is performed;
1141 * - locks are released after IO is complete.
1143 * Striping introduces major additional complexity into locking. The
1144 * fundamental problem is that it is generally unsafe to actively use (hold)
1145 * two locks on the different OST servers at the same time, as this introduces
1146 * inter-server dependency and can lead to cascading evictions.
1148 * Basic solution is to sub-divide large read/write IOs into smaller pieces so
1149 * that no multi-stripe locks are taken (note that this design abandons POSIX
1150 * read/write semantics). Such pieces ideally can be executed concurrently. At
1151 * the same time, certain types of IO cannot be sub-divived, without
1152 * sacrificing correctness. This includes:
1154 * - O_APPEND write, where [0, EOF] lock has to be taken, to guarantee
1157 * - ftruncate(fd, offset), where [offset, EOF] lock has to be taken.
1159 * Also, in the case of read(fd, buf, count) or write(fd, buf, count), where
1160 * buf is a part of memory mapped Lustre file, a lock or locks protecting buf
1161 * has to be held together with the usual lock on [offset, offset + count].
1163 * Interaction with DLM
1165 * In the expected setup, cl_lock is ultimately backed up by a collection of
1166 * DLM locks (struct ldlm_lock). Association between cl_lock and DLM lock is
1167 * implemented in osc layer, that also matches DLM events (ASTs, cancellation,
1168 * etc.) into cl_lock_operation calls. See struct osc_lock for a more detailed
1169 * description of interaction with DLM.
1175 struct cl_lock_descr {
1176 /** Object this lock is granted for. */
1177 struct cl_object *cld_obj;
1178 /** Index of the first page protected by this lock. */
1180 /** Index of the last page (inclusive) protected by this lock. */
1182 /** Group ID, for group lock */
1185 enum cl_lock_mode cld_mode;
1187 * flags to enqueue lock. A combination of bit-flags from
1188 * enum cl_enq_flags.
1190 __u32 cld_enq_flags;
1193 #define DDESCR "%s(%d):[%lu, %lu]:%x"
1194 #define PDESCR(descr) \
1195 cl_lock_mode_name((descr)->cld_mode), (descr)->cld_mode, \
1196 (descr)->cld_start, (descr)->cld_end, (descr)->cld_enq_flags
1198 const char *cl_lock_mode_name(const enum cl_lock_mode mode);
1201 * Layered client lock.
1204 /** List of slices. Immutable after creation. */
1205 struct list_head cll_layers;
1206 /** lock attribute, extent, cl_object, etc. */
1207 struct cl_lock_descr cll_descr;
1211 * Per-layer part of cl_lock
1213 * \see lov_lock, osc_lock
1215 struct cl_lock_slice {
1216 struct cl_lock *cls_lock;
1217 /** Object slice corresponding to this lock slice. Immutable after
1219 struct cl_object *cls_obj;
1220 const struct cl_lock_operations *cls_ops;
1221 /** Linkage into cl_lock::cll_layers. Immutable after creation. */
1222 struct list_head cls_linkage;
1227 * \see lov_lock_ops, osc_lock_ops
1229 struct cl_lock_operations {
1232 * Attempts to enqueue the lock. Called top-to-bottom.
1234 * \retval 0 this layer has enqueued the lock successfully
1235 * \retval >0 this layer has enqueued the lock, but need to wait on
1236 * @anchor for resources
1237 * \retval -ve failure
1239 * \see lov_lock_enqueue(), osc_lock_enqueue()
1241 int (*clo_enqueue)(const struct lu_env *env,
1242 const struct cl_lock_slice *slice,
1243 struct cl_io *io, struct cl_sync_io *anchor);
1245 * Cancel a lock, release its DLM lock ref, while does not cancel the
1248 void (*clo_cancel)(const struct lu_env *env,
1249 const struct cl_lock_slice *slice);
1252 * Destructor. Frees resources and the slice.
1254 * \see lov_lock_fini(), osc_lock_fini()
1256 void (*clo_fini)(const struct lu_env *env, struct cl_lock_slice *slice);
1258 * Optional debugging helper. Prints given lock slice.
1260 int (*clo_print)(const struct lu_env *env,
1261 void *cookie, lu_printer_t p,
1262 const struct cl_lock_slice *slice);
1265 #define CL_LOCK_DEBUG(mask, env, lock, format, ...) \
1267 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1268 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1269 cl_lock_print(env, &msgdata, lu_cdebug_printer, lock); \
1270 CDEBUG(mask, format , ## __VA_ARGS__); \
1274 #define CL_LOCK_ASSERT(expr, env, lock) do { \
1278 CL_LOCK_DEBUG(D_ERROR, env, lock, "failed at %s.\n", #expr); \
1284 /** \addtogroup cl_page_list cl_page_list
1285 * Page list used to perform collective operations on a group of pages.
1287 * Pages are added to the list one by one. cl_page_list acquires a reference
1288 * for every page in it. Page list is used to perform collective operations on
1291 * - submit pages for an immediate transfer,
1293 * - own pages on behalf of certain io (waiting for each page in turn),
1297 * When list is finalized, it releases references on all pages it still has.
1299 * \todo XXX concurrency control.
1303 struct cl_page_list {
1305 struct list_head pl_pages;
1306 struct task_struct *pl_owner;
1310 * A 2-queue of pages. A convenience data-type for common use case, 2-queue
1311 * contains an incoming page list and an outgoing page list.
1314 struct cl_page_list c2_qin;
1315 struct cl_page_list c2_qout;
1318 /** @} cl_page_list */
1320 /** \addtogroup cl_io cl_io
1325 * cl_io represents a high level I/O activity like
1326 * read(2)/write(2)/truncate(2) system call, or cancellation of an extent
1329 * cl_io is a layered object, much like cl_{object,page,lock} but with one
1330 * important distinction. We want to minimize number of calls to the allocator
1331 * in the fast path, e.g., in the case of read(2) when everything is cached:
1332 * client already owns the lock over region being read, and data are cached
1333 * due to read-ahead. To avoid allocation of cl_io layers in such situations,
1334 * per-layer io state is stored in the session, associated with the io, see
1335 * struct {vvp,lov,osc}_io for example. Sessions allocation is amortized
1336 * by using free-lists, see cl_env_get().
1338 * There is a small predefined number of possible io types, enumerated in enum
1341 * cl_io is a state machine, that can be advanced concurrently by the multiple
1342 * threads. It is up to these threads to control the concurrency and,
1343 * specifically, to detect when io is done, and its state can be safely
1346 * For read/write io overall execution plan is as following:
1348 * (0) initialize io state through all layers;
1350 * (1) loop: prepare chunk of work to do
1352 * (2) call all layers to collect locks they need to process current chunk
1354 * (3) sort all locks to avoid dead-locks, and acquire them
1356 * (4) process the chunk: call per-page methods
1357 * cl_io_operations::cio_prepare_write(),
1358 * cl_io_operations::cio_commit_write() for write)
1364 * To implement the "parallel IO mode", lov layer creates sub-io's (lazily to
1365 * address allocation efficiency issues mentioned above), and returns with the
1366 * special error condition from per-page method when current sub-io has to
1367 * block. This causes io loop to be repeated, and lov switches to the next
1368 * sub-io in its cl_io_operations::cio_iter_init() implementation.
1373 /** read system call */
1375 /** write system call */
1377 /** truncate, utime system calls */
1379 /** get data version */
1382 * page fault handling
1386 * fsync system call handling
1387 * To write out a range of file
1391 * glimpse. An io context to acquire glimpse lock.
1395 * Miscellaneous io. This is used for occasional io activity that
1396 * doesn't fit into other types. Currently this is used for:
1398 * - cancellation of an extent lock. This io exists as a context
1399 * to write dirty pages from under the lock being canceled back
1402 * - VM induced page write-out. An io context for writing page out
1403 * for memory cleansing;
1405 * - grouplock. An io context to acquire group lock.
1407 * CIT_MISC io is used simply as a context in which locks and pages
1408 * are manipulated. Such io has no internal "process", that is,
1409 * cl_io_loop() is never called for it.
1414 * To give advice about access of a file
1421 * States of cl_io state machine
1424 /** Not initialized. */
1428 /** IO iteration started. */
1432 /** Actual IO is in progress. */
1434 /** IO for the current iteration finished. */
1436 /** Locks released. */
1438 /** Iteration completed. */
1440 /** cl_io finalized. */
1445 * IO state private for a layer.
1447 * This is usually embedded into layer session data, rather than allocated
1450 * \see vvp_io, lov_io, osc_io
1452 struct cl_io_slice {
1453 struct cl_io *cis_io;
1454 /** corresponding object slice. Immutable after creation. */
1455 struct cl_object *cis_obj;
1456 /** io operations. Immutable after creation. */
1457 const struct cl_io_operations *cis_iop;
1459 * linkage into a list of all slices for a given cl_io, hanging off
1460 * cl_io::ci_layers. Immutable after creation.
1462 struct list_head cis_linkage;
1465 typedef void (*cl_commit_cbt)(const struct lu_env *, struct cl_io *,
1468 struct cl_read_ahead {
1469 /* Maximum page index the readahead window will end.
1470 * This is determined DLM lock coverage, RPC and stripe boundary.
1471 * cra_end is included. */
1473 /* optimal RPC size for this read, by pages */
1474 unsigned long cra_rpc_size;
1475 /* Release callback. If readahead holds resources underneath, this
1476 * function should be called to release it. */
1477 void (*cra_release)(const struct lu_env *env, void *cbdata);
1478 /* Callback data for cra_release routine */
1482 static inline void cl_read_ahead_release(const struct lu_env *env,
1483 struct cl_read_ahead *ra)
1485 if (ra->cra_release != NULL)
1486 ra->cra_release(env, ra->cra_cbdata);
1487 memset(ra, 0, sizeof(*ra));
1492 * Per-layer io operations.
1493 * \see vvp_io_ops, lov_io_ops, lovsub_io_ops, osc_io_ops
1495 struct cl_io_operations {
1497 * Vector of io state transition methods for every io type.
1499 * \see cl_page_operations::io
1503 * Prepare io iteration at a given layer.
1505 * Called top-to-bottom at the beginning of each iteration of
1506 * "io loop" (if it makes sense for this type of io). Here
1507 * layer selects what work it will do during this iteration.
1509 * \see cl_io_operations::cio_iter_fini()
1511 int (*cio_iter_init) (const struct lu_env *env,
1512 const struct cl_io_slice *slice);
1514 * Finalize io iteration.
1516 * Called bottom-to-top at the end of each iteration of "io
1517 * loop". Here layers can decide whether IO has to be
1520 * \see cl_io_operations::cio_iter_init()
1522 void (*cio_iter_fini) (const struct lu_env *env,
1523 const struct cl_io_slice *slice);
1525 * Collect locks for the current iteration of io.
1527 * Called top-to-bottom to collect all locks necessary for
1528 * this iteration. This methods shouldn't actually enqueue
1529 * anything, instead it should post a lock through
1530 * cl_io_lock_add(). Once all locks are collected, they are
1531 * sorted and enqueued in the proper order.
1533 int (*cio_lock) (const struct lu_env *env,
1534 const struct cl_io_slice *slice);
1536 * Finalize unlocking.
1538 * Called bottom-to-top to finish layer specific unlocking
1539 * functionality, after generic code released all locks
1540 * acquired by cl_io_operations::cio_lock().
1542 void (*cio_unlock)(const struct lu_env *env,
1543 const struct cl_io_slice *slice);
1545 * Start io iteration.
1547 * Once all locks are acquired, called top-to-bottom to
1548 * commence actual IO. In the current implementation,
1549 * top-level vvp_io_{read,write}_start() does all the work
1550 * synchronously by calling generic_file_*(), so other layers
1551 * are called when everything is done.
1553 int (*cio_start)(const struct lu_env *env,
1554 const struct cl_io_slice *slice);
1556 * Called top-to-bottom at the end of io loop. Here layer
1557 * might wait for an unfinished asynchronous io.
1559 void (*cio_end) (const struct lu_env *env,
1560 const struct cl_io_slice *slice);
1562 * Called bottom-to-top to notify layers that read/write IO
1563 * iteration finished, with \a nob bytes transferred.
1565 void (*cio_advance)(const struct lu_env *env,
1566 const struct cl_io_slice *slice,
1569 * Called once per io, bottom-to-top to release io resources.
1571 void (*cio_fini) (const struct lu_env *env,
1572 const struct cl_io_slice *slice);
1576 * Submit pages from \a queue->c2_qin for IO, and move
1577 * successfully submitted pages into \a queue->c2_qout. Return
1578 * non-zero if failed to submit even the single page. If
1579 * submission failed after some pages were moved into \a
1580 * queue->c2_qout, completion callback with non-zero ioret is
1583 int (*cio_submit)(const struct lu_env *env,
1584 const struct cl_io_slice *slice,
1585 enum cl_req_type crt,
1586 struct cl_2queue *queue);
1588 * Queue async page for write.
1589 * The difference between cio_submit and cio_queue is that
1590 * cio_submit is for urgent request.
1592 int (*cio_commit_async)(const struct lu_env *env,
1593 const struct cl_io_slice *slice,
1594 struct cl_page_list *queue, int from, int to,
1597 * Decide maximum read ahead extent
1599 * \pre io->ci_type == CIT_READ
1601 int (*cio_read_ahead)(const struct lu_env *env,
1602 const struct cl_io_slice *slice,
1603 pgoff_t start, struct cl_read_ahead *ra);
1605 * Optional debugging helper. Print given io slice.
1607 int (*cio_print)(const struct lu_env *env, void *cookie,
1608 lu_printer_t p, const struct cl_io_slice *slice);
1612 * Flags to lock enqueue procedure.
1617 * instruct server to not block, if conflicting lock is found. Instead
1618 * -EWOULDBLOCK is returned immediately.
1620 CEF_NONBLOCK = 0x00000001,
1622 * Tell lower layers this is a glimpse request, translated to
1623 * LDLM_FL_HAS_INTENT at LDLM layer.
1625 * Also, because glimpse locks never block other locks, we count this
1626 * as automatically compatible with other osc locks.
1627 * (see osc_lock_compatible)
1629 CEF_GLIMPSE = 0x00000002,
1631 * tell the server to instruct (though a flag in the blocking ast) an
1632 * owner of the conflicting lock, that it can drop dirty pages
1633 * protected by this lock, without sending them to the server.
1635 CEF_DISCARD_DATA = 0x00000004,
1637 * tell the sub layers that it must be a `real' lock. This is used for
1638 * mmapped-buffer locks, glimpse locks, manually requested locks
1639 * (LU_LADVISE_LOCKAHEAD) that must never be converted into lockless
1642 * \see vvp_mmap_locks(), cl_glimpse_lock, cl_request_lock().
1644 CEF_MUST = 0x00000008,
1646 * tell the sub layers that never request a `real' lock. This flag is
1647 * not used currently.
1649 * cl_io::ci_lockreq and CEF_{MUST,NEVER} flags specify lockless
1650 * conversion policy: ci_lockreq describes generic information of lock
1651 * requirement for this IO, especially for locks which belong to the
1652 * object doing IO; however, lock itself may have precise requirements
1653 * that are described by the enqueue flags.
1655 CEF_NEVER = 0x00000010,
1657 * tell the dlm layer this is a speculative lock request
1658 * speculative lock requests are locks which are not requested as part
1659 * of an I/O operation. Instead, they are requested because we expect
1660 * to use them in the future. They are requested asynchronously at the
1663 * Currently used for asynchronous glimpse locks and manually requested
1664 * locks (LU_LADVISE_LOCKAHEAD).
1666 CEF_SPECULATIVE = 0x00000020,
1668 * enqueue a lock to test DLM lock existence.
1670 CEF_PEEK = 0x00000040,
1672 * Lock match only. Used by group lock in I/O as group lock
1673 * is known to exist.
1675 CEF_LOCK_MATCH = 0x00000080,
1677 * tell the DLM layer to lock only the requested range
1679 CEF_LOCK_NO_EXPAND = 0x00000100,
1681 * mask of enq_flags.
1683 CEF_MASK = 0x000001ff,
1687 * Link between lock and io. Intermediate structure is needed, because the
1688 * same lock can be part of multiple io's simultaneously.
1690 struct cl_io_lock_link {
1691 /** linkage into one of cl_lockset lists. */
1692 struct list_head cill_linkage;
1693 struct cl_lock cill_lock;
1694 /** optional destructor */
1695 void (*cill_fini)(const struct lu_env *env,
1696 struct cl_io_lock_link *link);
1698 #define cill_descr cill_lock.cll_descr
1701 * Lock-set represents a collection of locks, that io needs at a
1702 * time. Generally speaking, client tries to avoid holding multiple locks when
1705 * - holding extent locks over multiple ost's introduces the danger of
1706 * "cascading timeouts";
1708 * - holding multiple locks over the same ost is still dead-lock prone,
1709 * see comment in osc_lock_enqueue(),
1711 * but there are certain situations where this is unavoidable:
1713 * - O_APPEND writes have to take [0, EOF] lock for correctness;
1715 * - truncate has to take [new-size, EOF] lock for correctness;
1717 * - SNS has to take locks across full stripe for correctness;
1719 * - in the case when user level buffer, supplied to {read,write}(file0),
1720 * is a part of a memory mapped lustre file, client has to take a dlm
1721 * locks on file0, and all files that back up the buffer (or a part of
1722 * the buffer, that is being processed in the current chunk, in any
1723 * case, there are situations where at least 2 locks are necessary).
1725 * In such cases we at least try to take locks in the same consistent
1726 * order. To this end, all locks are first collected, then sorted, and then
1730 /** locks to be acquired. */
1731 struct list_head cls_todo;
1732 /** locks acquired. */
1733 struct list_head cls_done;
1737 * Lock requirements(demand) for IO. It should be cl_io_lock_req,
1738 * but 'req' is always to be thought as 'request' :-)
1740 enum cl_io_lock_dmd {
1741 /** Always lock data (e.g., O_APPEND). */
1743 /** Layers are free to decide between local and global locking. */
1745 /** Never lock: there is no cache (e.g., liblustre). */
1749 enum cl_fsync_mode {
1750 /** start writeback, do not wait for them to finish */
1752 /** start writeback and wait for them to finish */
1754 /** discard all of dirty pages in a specific file range */
1755 CL_FSYNC_DISCARD = 2,
1756 /** start writeback and make sure they have reached storage before
1757 * return. OST_SYNC RPC must be issued and finished */
1761 struct cl_io_rw_common {
1770 * cl_io is shared by all threads participating in this IO (in current
1771 * implementation only one thread advances IO, but parallel IO design and
1772 * concurrent copy_*_user() require multiple threads acting on the same IO. It
1773 * is up to these threads to serialize their activities, including updates to
1774 * mutable cl_io fields.
1777 /** type of this IO. Immutable after creation. */
1778 enum cl_io_type ci_type;
1779 /** current state of cl_io state machine. */
1780 enum cl_io_state ci_state;
1781 /** main object this io is against. Immutable after creation. */
1782 struct cl_object *ci_obj;
1784 * Upper layer io, of which this io is a part of. Immutable after
1787 struct cl_io *ci_parent;
1788 /** List of slices. Immutable after creation. */
1789 struct list_head ci_layers;
1790 /** list of locks (to be) acquired by this io. */
1791 struct cl_lockset ci_lockset;
1792 /** lock requirements, this is just a help info for sublayers. */
1793 enum cl_io_lock_dmd ci_lockreq;
1794 /** layout version when this IO occurs */
1795 __u32 ci_layout_version;
1798 struct cl_io_rw_common rd;
1801 struct cl_io_rw_common wr;
1805 struct cl_io_rw_common ci_rw;
1806 struct cl_setattr_io {
1807 struct ost_lvb sa_attr;
1808 unsigned int sa_attr_flags;
1809 unsigned int sa_avalid; /* ATTR_* */
1810 unsigned int sa_xvalid; /* OP_XVALID */
1811 int sa_stripe_index;
1812 struct ost_layout sa_layout;
1813 const struct lu_fid *sa_parent_fid;
1815 struct cl_data_version_io {
1816 u64 dv_data_version;
1817 u32 dv_layout_version;
1820 struct cl_fault_io {
1821 /** page index within file. */
1823 /** bytes valid byte on a faulted page. */
1825 /** writable page? for nopage() only */
1827 /** page of an executable? */
1829 /** page_mkwrite() */
1831 /** resulting page */
1832 struct cl_page *ft_page;
1834 struct cl_fsync_io {
1837 /** file system level fid */
1838 struct lu_fid *fi_fid;
1839 enum cl_fsync_mode fi_mode;
1840 /* how many pages were written/discarded */
1841 unsigned int fi_nr_written;
1843 struct cl_ladvise_io {
1846 /** file system level fid */
1847 struct lu_fid *li_fid;
1848 enum lu_ladvise_type li_advice;
1852 struct cl_2queue ci_queue;
1855 unsigned int ci_continue:1,
1857 * This io has held grouplock, to inform sublayers that
1858 * don't do lockless i/o.
1862 * The whole IO need to be restarted because layout has been changed
1866 * to not refresh layout - the IO issuer knows that the layout won't
1867 * change(page operations, layout change causes all page to be
1868 * discarded), or it doesn't matter if it changes(sync).
1872 * Need MDS intervention to complete a write.
1873 * Write intent is required for the following cases:
1874 * 1. component being written is not initialized, or
1875 * 2. the mirrored files are NOT in WRITE_PENDING state.
1877 ci_need_write_intent:1,
1879 * Check if layout changed after the IO finishes. Mainly for HSM
1880 * requirement. If IO occurs to openning files, it doesn't need to
1881 * verify layout because HSM won't release openning files.
1882 * Right now, only two opertaions need to verify layout: glimpse
1887 * file is released, restore has to to be triggered by vvp layer
1889 ci_restore_needed:1,
1894 /* Tell sublayers not to expand LDLM locks requested for this IO */
1895 ci_lock_no_expand:1,
1897 * Set if non-delay RPC should be used for this IO.
1899 * If this file has multiple mirrors, and if the OSTs of the current
1900 * mirror is inaccessible, non-delay RPC would error out quickly so
1901 * that the upper layer can try to access the next mirror.
1905 * How many times the read has retried before this one.
1906 * Set by the top level and consumed by the LOV.
1908 unsigned ci_ndelay_tried;
1910 * Designated mirror index for this I/O.
1912 unsigned ci_designated_mirror;
1914 * Number of pages owned by this IO. For invariant checking.
1916 unsigned ci_owned_nr;
1918 * Range of write intent. Valid if ci_need_write_intent is set.
1920 struct lu_extent ci_write_intent;
1926 * Per-transfer attributes.
1928 struct cl_req_attr {
1929 enum cl_req_type cra_type;
1931 struct cl_page *cra_page;
1932 /** Generic attributes for the server consumption. */
1933 struct obdo *cra_oa;
1935 char cra_jobid[LUSTRE_JOBID_SIZE];
1938 enum cache_stats_item {
1939 /** how many cache lookups were performed */
1941 /** how many times cache lookup resulted in a hit */
1943 /** how many entities are in the cache right now */
1945 /** how many entities in the cache are actively used (and cannot be
1946 * evicted) right now */
1948 /** how many entities were created at all */
1953 #define CS_NAMES { "lookup", "hit", "total", "busy", "create" }
1956 * Stats for a generic cache (similar to inode, lu_object, etc. caches).
1958 struct cache_stats {
1959 const char *cs_name;
1960 atomic_t cs_stats[CS_NR];
1963 /** These are not exported so far */
1964 void cache_stats_init (struct cache_stats *cs, const char *name);
1967 * Client-side site. This represents particular client stack. "Global"
1968 * variables should (directly or indirectly) be added here to allow multiple
1969 * clients to co-exist in the single address space.
1972 struct lu_site cs_lu;
1974 * Statistical counters. Atomics do not scale, something better like
1975 * per-cpu counters is needed.
1977 * These are exported as /proc/fs/lustre/llite/.../site
1979 * When interpreting keep in mind that both sub-locks (and sub-pages)
1980 * and top-locks (and top-pages) are accounted here.
1982 struct cache_stats cs_pages;
1983 atomic_t cs_pages_state[CPS_NR];
1986 int cl_site_init(struct cl_site *s, struct cl_device *top);
1987 void cl_site_fini(struct cl_site *s);
1988 void cl_stack_fini(const struct lu_env *env, struct cl_device *cl);
1991 * Output client site statistical counters into a buffer. Suitable for
1992 * ll_rd_*()-style functions.
1994 int cl_site_stats_print(const struct cl_site *site, struct seq_file *m);
1999 * Type conversion and accessory functions.
2003 static inline struct cl_site *lu2cl_site(const struct lu_site *site)
2005 return container_of(site, struct cl_site, cs_lu);
2008 static inline struct cl_device *lu2cl_dev(const struct lu_device *d)
2010 LASSERT(d == NULL || IS_ERR(d) || lu_device_is_cl(d));
2011 return container_of0(d, struct cl_device, cd_lu_dev);
2014 static inline struct lu_device *cl2lu_dev(struct cl_device *d)
2016 return &d->cd_lu_dev;
2019 static inline struct cl_object *lu2cl(const struct lu_object *o)
2021 LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->lo_dev));
2022 return container_of0(o, struct cl_object, co_lu);
2025 static inline const struct cl_object_conf *
2026 lu2cl_conf(const struct lu_object_conf *conf)
2028 return container_of0(conf, struct cl_object_conf, coc_lu);
2031 static inline struct cl_object *cl_object_next(const struct cl_object *obj)
2033 return obj ? lu2cl(lu_object_next(&obj->co_lu)) : NULL;
2036 static inline struct cl_object_header *luh2coh(const struct lu_object_header *h)
2038 return container_of0(h, struct cl_object_header, coh_lu);
2041 static inline struct cl_site *cl_object_site(const struct cl_object *obj)
2043 return lu2cl_site(obj->co_lu.lo_dev->ld_site);
2047 struct cl_object_header *cl_object_header(const struct cl_object *obj)
2049 return luh2coh(obj->co_lu.lo_header);
2052 static inline int cl_device_init(struct cl_device *d, struct lu_device_type *t)
2054 return lu_device_init(&d->cd_lu_dev, t);
2057 static inline void cl_device_fini(struct cl_device *d)
2059 lu_device_fini(&d->cd_lu_dev);
2062 void cl_page_slice_add(struct cl_page *page, struct cl_page_slice *slice,
2063 struct cl_object *obj, pgoff_t index,
2064 const struct cl_page_operations *ops);
2065 void cl_lock_slice_add(struct cl_lock *lock, struct cl_lock_slice *slice,
2066 struct cl_object *obj,
2067 const struct cl_lock_operations *ops);
2068 void cl_io_slice_add(struct cl_io *io, struct cl_io_slice *slice,
2069 struct cl_object *obj, const struct cl_io_operations *ops);
2072 /** \defgroup cl_object cl_object
2074 struct cl_object *cl_object_top (struct cl_object *o);
2075 struct cl_object *cl_object_find(const struct lu_env *env, struct cl_device *cd,
2076 const struct lu_fid *fid,
2077 const struct cl_object_conf *c);
2079 int cl_object_header_init(struct cl_object_header *h);
2080 void cl_object_header_fini(struct cl_object_header *h);
2081 void cl_object_put (const struct lu_env *env, struct cl_object *o);
2082 void cl_object_get (struct cl_object *o);
2083 void cl_object_attr_lock (struct cl_object *o);
2084 void cl_object_attr_unlock(struct cl_object *o);
2085 int cl_object_attr_get(const struct lu_env *env, struct cl_object *obj,
2086 struct cl_attr *attr);
2087 int cl_object_attr_update(const struct lu_env *env, struct cl_object *obj,
2088 const struct cl_attr *attr, unsigned valid);
2089 int cl_object_glimpse (const struct lu_env *env, struct cl_object *obj,
2090 struct ost_lvb *lvb);
2091 int cl_conf_set (const struct lu_env *env, struct cl_object *obj,
2092 const struct cl_object_conf *conf);
2093 int cl_object_prune (const struct lu_env *env, struct cl_object *obj);
2094 void cl_object_kill (const struct lu_env *env, struct cl_object *obj);
2095 int cl_object_getstripe(const struct lu_env *env, struct cl_object *obj,
2096 struct lov_user_md __user *lum, size_t size);
2097 int cl_object_fiemap(const struct lu_env *env, struct cl_object *obj,
2098 struct ll_fiemap_info_key *fmkey, struct fiemap *fiemap,
2100 int cl_object_layout_get(const struct lu_env *env, struct cl_object *obj,
2101 struct cl_layout *cl);
2102 loff_t cl_object_maxbytes(struct cl_object *obj);
2105 * Returns true, iff \a o0 and \a o1 are slices of the same object.
2107 static inline int cl_object_same(struct cl_object *o0, struct cl_object *o1)
2109 return cl_object_header(o0) == cl_object_header(o1);
2112 static inline void cl_object_page_init(struct cl_object *clob, int size)
2114 clob->co_slice_off = cl_object_header(clob)->coh_page_bufsize;
2115 cl_object_header(clob)->coh_page_bufsize += cfs_size_round(size);
2116 WARN_ON(cl_object_header(clob)->coh_page_bufsize > 512);
2119 static inline void *cl_object_page_slice(struct cl_object *clob,
2120 struct cl_page *page)
2122 return (void *)((char *)page + clob->co_slice_off);
2126 * Return refcount of cl_object.
2128 static inline int cl_object_refc(struct cl_object *clob)
2130 struct lu_object_header *header = clob->co_lu.lo_header;
2131 return atomic_read(&header->loh_ref);
2136 /** \defgroup cl_page cl_page
2144 /* callback of cl_page_gang_lookup() */
2146 struct cl_page *cl_page_find (const struct lu_env *env,
2147 struct cl_object *obj,
2148 pgoff_t idx, struct page *vmpage,
2149 enum cl_page_type type);
2150 struct cl_page *cl_page_alloc (const struct lu_env *env,
2151 struct cl_object *o, pgoff_t ind,
2152 struct page *vmpage,
2153 enum cl_page_type type);
2154 void cl_page_get (struct cl_page *page);
2155 void cl_page_put (const struct lu_env *env,
2156 struct cl_page *page);
2157 void cl_pagevec_put (const struct lu_env *env,
2158 struct cl_page *page,
2159 struct pagevec *pvec);
2160 void cl_page_print (const struct lu_env *env, void *cookie,
2161 lu_printer_t printer,
2162 const struct cl_page *pg);
2163 void cl_page_header_print(const struct lu_env *env, void *cookie,
2164 lu_printer_t printer,
2165 const struct cl_page *pg);
2166 struct cl_page *cl_vmpage_page (struct page *vmpage, struct cl_object *obj);
2167 struct cl_page *cl_page_top (struct cl_page *page);
2169 const struct cl_page_slice *cl_page_at(const struct cl_page *page,
2170 const struct lu_device_type *dtype);
2175 * Functions dealing with the ownership of page by io.
2179 int cl_page_own (const struct lu_env *env,
2180 struct cl_io *io, struct cl_page *page);
2181 int cl_page_own_try (const struct lu_env *env,
2182 struct cl_io *io, struct cl_page *page);
2183 void cl_page_assume (const struct lu_env *env,
2184 struct cl_io *io, struct cl_page *page);
2185 void cl_page_unassume (const struct lu_env *env,
2186 struct cl_io *io, struct cl_page *pg);
2187 void cl_page_disown (const struct lu_env *env,
2188 struct cl_io *io, struct cl_page *page);
2189 int cl_page_is_owned (const struct cl_page *pg, const struct cl_io *io);
2196 * Functions dealing with the preparation of a page for a transfer, and
2197 * tracking transfer state.
2200 int cl_page_prep (const struct lu_env *env, struct cl_io *io,
2201 struct cl_page *pg, enum cl_req_type crt);
2202 void cl_page_completion (const struct lu_env *env,
2203 struct cl_page *pg, enum cl_req_type crt, int ioret);
2204 int cl_page_make_ready (const struct lu_env *env, struct cl_page *pg,
2205 enum cl_req_type crt);
2206 int cl_page_cache_add (const struct lu_env *env, struct cl_io *io,
2207 struct cl_page *pg, enum cl_req_type crt);
2208 void cl_page_clip (const struct lu_env *env, struct cl_page *pg,
2210 int cl_page_cancel (const struct lu_env *env, struct cl_page *page);
2211 int cl_page_flush (const struct lu_env *env, struct cl_io *io,
2212 struct cl_page *pg);
2218 * \name helper routines
2219 * Functions to discard, delete and export a cl_page.
2222 void cl_page_discard(const struct lu_env *env, struct cl_io *io,
2223 struct cl_page *pg);
2224 void cl_page_delete(const struct lu_env *env, struct cl_page *pg);
2225 int cl_page_is_vmlocked(const struct lu_env *env,
2226 const struct cl_page *pg);
2227 void cl_page_touch(const struct lu_env *env, const struct cl_page *pg,
2229 void cl_page_export(const struct lu_env *env,
2230 struct cl_page *pg, int uptodate);
2231 loff_t cl_offset(const struct cl_object *obj, pgoff_t idx);
2232 pgoff_t cl_index(const struct cl_object *obj, loff_t offset);
2233 size_t cl_page_size(const struct cl_object *obj);
2235 void cl_lock_print(const struct lu_env *env, void *cookie,
2236 lu_printer_t printer, const struct cl_lock *lock);
2237 void cl_lock_descr_print(const struct lu_env *env, void *cookie,
2238 lu_printer_t printer,
2239 const struct cl_lock_descr *descr);
2243 * Data structure managing a client's cached pages. A count of
2244 * "unstable" pages is maintained, and an LRU of clean pages is
2245 * maintained. "unstable" pages are pages pinned by the ptlrpc
2246 * layer for recovery purposes.
2248 struct cl_client_cache {
2250 * # of client cache refcount
2251 * # of users (OSCs) + 2 (held by llite and lov)
2255 * # of threads are doing shrinking
2257 unsigned int ccc_lru_shrinkers;
2259 * # of LRU entries available
2261 atomic_long_t ccc_lru_left;
2263 * List of entities(OSCs) for this LRU cache
2265 struct list_head ccc_lru;
2267 * Max # of LRU entries
2269 unsigned long ccc_lru_max;
2271 * Lock to protect ccc_lru list
2273 spinlock_t ccc_lru_lock;
2275 * Set if unstable check is enabled
2277 unsigned int ccc_unstable_check:1;
2279 * # of unstable pages for this mount point
2281 atomic_long_t ccc_unstable_nr;
2283 * Waitq for awaiting unstable pages to reach zero.
2284 * Used at umounting time and signaled on BRW commit
2286 wait_queue_head_t ccc_unstable_waitq;
2289 * cl_cache functions
2291 struct cl_client_cache *cl_cache_init(unsigned long lru_page_max);
2292 void cl_cache_incref(struct cl_client_cache *cache);
2293 void cl_cache_decref(struct cl_client_cache *cache);
2297 /** \defgroup cl_lock cl_lock
2299 int cl_lock_request(const struct lu_env *env, struct cl_io *io,
2300 struct cl_lock *lock);
2301 int cl_lock_init(const struct lu_env *env, struct cl_lock *lock,
2302 const struct cl_io *io);
2303 void cl_lock_fini(const struct lu_env *env, struct cl_lock *lock);
2304 const struct cl_lock_slice *cl_lock_at(const struct cl_lock *lock,
2305 const struct lu_device_type *dtype);
2306 void cl_lock_release(const struct lu_env *env, struct cl_lock *lock);
2308 int cl_lock_enqueue(const struct lu_env *env, struct cl_io *io,
2309 struct cl_lock *lock, struct cl_sync_io *anchor);
2310 void cl_lock_cancel(const struct lu_env *env, struct cl_lock *lock);
2314 /** \defgroup cl_io cl_io
2317 int cl_io_init (const struct lu_env *env, struct cl_io *io,
2318 enum cl_io_type iot, struct cl_object *obj);
2319 int cl_io_sub_init (const struct lu_env *env, struct cl_io *io,
2320 enum cl_io_type iot, struct cl_object *obj);
2321 int cl_io_rw_init (const struct lu_env *env, struct cl_io *io,
2322 enum cl_io_type iot, loff_t pos, size_t count);
2323 int cl_io_loop (const struct lu_env *env, struct cl_io *io);
2325 void cl_io_fini (const struct lu_env *env, struct cl_io *io);
2326 int cl_io_iter_init (const struct lu_env *env, struct cl_io *io);
2327 void cl_io_iter_fini (const struct lu_env *env, struct cl_io *io);
2328 int cl_io_lock (const struct lu_env *env, struct cl_io *io);
2329 void cl_io_unlock (const struct lu_env *env, struct cl_io *io);
2330 int cl_io_start (const struct lu_env *env, struct cl_io *io);
2331 void cl_io_end (const struct lu_env *env, struct cl_io *io);
2332 int cl_io_lock_add (const struct lu_env *env, struct cl_io *io,
2333 struct cl_io_lock_link *link);
2334 int cl_io_lock_alloc_add(const struct lu_env *env, struct cl_io *io,
2335 struct cl_lock_descr *descr);
2336 int cl_io_submit_rw (const struct lu_env *env, struct cl_io *io,
2337 enum cl_req_type iot, struct cl_2queue *queue);
2338 int cl_io_submit_sync (const struct lu_env *env, struct cl_io *io,
2339 enum cl_req_type iot, struct cl_2queue *queue,
2341 int cl_io_commit_async (const struct lu_env *env, struct cl_io *io,
2342 struct cl_page_list *queue, int from, int to,
2344 int cl_io_read_ahead (const struct lu_env *env, struct cl_io *io,
2345 pgoff_t start, struct cl_read_ahead *ra);
2346 void cl_io_rw_advance (const struct lu_env *env, struct cl_io *io,
2348 int cl_io_cancel (const struct lu_env *env, struct cl_io *io,
2349 struct cl_page_list *queue);
2352 * True, iff \a io is an O_APPEND write(2).
2354 static inline int cl_io_is_append(const struct cl_io *io)
2356 return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_append;
2359 static inline int cl_io_is_sync_write(const struct cl_io *io)
2361 return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_sync;
2364 static inline int cl_io_is_mkwrite(const struct cl_io *io)
2366 return io->ci_type == CIT_FAULT && io->u.ci_fault.ft_mkwrite;
2370 * True, iff \a io is a truncate(2).
2372 static inline int cl_io_is_trunc(const struct cl_io *io)
2374 return io->ci_type == CIT_SETATTR &&
2375 (io->u.ci_setattr.sa_avalid & ATTR_SIZE);
2378 struct cl_io *cl_io_top(struct cl_io *io);
2380 void cl_io_print(const struct lu_env *env, void *cookie,
2381 lu_printer_t printer, const struct cl_io *io);
2383 #define CL_IO_SLICE_CLEAN(foo_io, base) \
2385 typeof(foo_io) __foo_io = (foo_io); \
2387 memset(&__foo_io->base, 0, \
2388 sizeof(*__foo_io) - offsetof(typeof(*__foo_io), base)); \
2393 /** \defgroup cl_page_list cl_page_list
2397 * Last page in the page list.
2399 static inline struct cl_page *cl_page_list_last(struct cl_page_list *plist)
2401 LASSERT(plist->pl_nr > 0);
2402 return list_entry(plist->pl_pages.prev, struct cl_page, cp_batch);
2405 static inline struct cl_page *cl_page_list_first(struct cl_page_list *plist)
2407 LASSERT(plist->pl_nr > 0);
2408 return list_entry(plist->pl_pages.next, struct cl_page, cp_batch);
2412 * Iterate over pages in a page list.
2414 #define cl_page_list_for_each(page, list) \
2415 list_for_each_entry((page), &(list)->pl_pages, cp_batch)
2418 * Iterate over pages in a page list, taking possible removals into account.
2420 #define cl_page_list_for_each_safe(page, temp, list) \
2421 list_for_each_entry_safe((page), (temp), &(list)->pl_pages, cp_batch)
2423 void cl_page_list_init (struct cl_page_list *plist);
2424 void cl_page_list_add (struct cl_page_list *plist, struct cl_page *page);
2425 void cl_page_list_move (struct cl_page_list *dst, struct cl_page_list *src,
2426 struct cl_page *page);
2427 void cl_page_list_move_head(struct cl_page_list *dst, struct cl_page_list *src,
2428 struct cl_page *page);
2429 void cl_page_list_splice (struct cl_page_list *list,
2430 struct cl_page_list *head);
2431 void cl_page_list_del (const struct lu_env *env,
2432 struct cl_page_list *plist, struct cl_page *page);
2433 void cl_page_list_disown (const struct lu_env *env,
2434 struct cl_io *io, struct cl_page_list *plist);
2435 void cl_page_list_assume (const struct lu_env *env,
2436 struct cl_io *io, struct cl_page_list *plist);
2437 void cl_page_list_discard(const struct lu_env *env,
2438 struct cl_io *io, struct cl_page_list *plist);
2439 void cl_page_list_fini (const struct lu_env *env, struct cl_page_list *plist);
2441 void cl_2queue_init (struct cl_2queue *queue);
2442 void cl_2queue_add (struct cl_2queue *queue, struct cl_page *page);
2443 void cl_2queue_disown (const struct lu_env *env,
2444 struct cl_io *io, struct cl_2queue *queue);
2445 void cl_2queue_assume (const struct lu_env *env,
2446 struct cl_io *io, struct cl_2queue *queue);
2447 void cl_2queue_discard (const struct lu_env *env,
2448 struct cl_io *io, struct cl_2queue *queue);
2449 void cl_2queue_fini (const struct lu_env *env, struct cl_2queue *queue);
2450 void cl_2queue_init_page(struct cl_2queue *queue, struct cl_page *page);
2452 /** @} cl_page_list */
2454 void cl_req_attr_set(const struct lu_env *env, struct cl_object *obj,
2455 struct cl_req_attr *attr);
2457 /** \defgroup cl_sync_io cl_sync_io
2461 * Anchor for synchronous transfer. This is allocated on a stack by thread
2462 * doing synchronous transfer, and a pointer to this structure is set up in
2463 * every page submitted for transfer. Transfer completion routine updates
2464 * anchor and wakes up waiting thread when transfer is complete.
2467 /** number of pages yet to be transferred. */
2468 atomic_t csi_sync_nr;
2471 /** barrier of destroy this structure */
2472 atomic_t csi_barrier;
2473 /** completion to be signaled when transfer is complete. */
2474 wait_queue_head_t csi_waitq;
2475 /** callback to invoke when this IO is finished */
2476 void (*csi_end_io)(const struct lu_env *,
2477 struct cl_sync_io *);
2480 void cl_sync_io_init(struct cl_sync_io *anchor, int nr,
2481 void (*end)(const struct lu_env *, struct cl_sync_io *));
2482 int cl_sync_io_wait(const struct lu_env *env, struct cl_sync_io *anchor,
2484 void cl_sync_io_note(const struct lu_env *env, struct cl_sync_io *anchor,
2486 void cl_sync_io_end(const struct lu_env *env, struct cl_sync_io *anchor);
2488 /** @} cl_sync_io */
2490 /** \defgroup cl_env cl_env
2492 * lu_env handling for a client.
2494 * lu_env is an environment within which lustre code executes. Its major part
2495 * is lu_context---a fast memory allocation mechanism that is used to conserve
2496 * precious kernel stack space. Originally lu_env was designed for a server,
2499 * - there is a (mostly) fixed number of threads, and
2501 * - call chains have no non-lustre portions inserted between lustre code.
2503 * On a client both these assumtpion fails, because every user thread can
2504 * potentially execute lustre code as part of a system call, and lustre calls
2505 * into VFS or MM that call back into lustre.
2507 * To deal with that, cl_env wrapper functions implement the following
2510 * - allocation and destruction of environment is amortized by caching no
2511 * longer used environments instead of destroying them;
2513 * \see lu_env, lu_context, lu_context_key
2516 struct lu_env *cl_env_get(__u16 *refcheck);
2517 struct lu_env *cl_env_alloc(__u16 *refcheck, __u32 tags);
2518 void cl_env_put(struct lu_env *env, __u16 *refcheck);
2519 unsigned cl_env_cache_purge(unsigned nr);
2520 struct lu_env *cl_env_percpu_get(void);
2521 void cl_env_percpu_put(struct lu_env *env);
2528 void cl_attr2lvb(struct ost_lvb *lvb, const struct cl_attr *attr);
2529 void cl_lvb2attr(struct cl_attr *attr, const struct ost_lvb *lvb);
2531 struct cl_device *cl_type_setup(const struct lu_env *env, struct lu_site *site,
2532 struct lu_device_type *ldt,
2533 struct lu_device *next);
2536 int cl_global_init(void);
2537 void cl_global_fini(void);
2539 #endif /* _LINUX_CL_OBJECT_H */