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14 * in the LICENSE file that accompanied this code).
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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 <libcfs/libcfs_ptask.h>
96 #include <lu_object.h>
97 #include <linux/atomic.h>
98 #include <linux/mutex.h>
99 #include <linux/radix-tree.h>
100 #include <linux/spinlock.h>
101 #include <linux/wait.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;
124 extern struct cfs_ptask_engine *cl_io_engine;
127 * Device in the client stack.
129 * \see vvp_device, lov_device, lovsub_device, osc_device
133 struct lu_device cd_lu_dev;
136 /** \addtogroup cl_object cl_object
139 * "Data attributes" of cl_object. Data attributes can be updated
140 * independently for a sub-object, and top-object's attributes are calculated
141 * from sub-objects' ones.
144 /** Object size, in bytes */
147 * Known minimal size, in bytes.
149 * This is only valid when at least one DLM lock is held.
152 /** Modification time. Measured in seconds since epoch. */
154 /** Access time. Measured in seconds since epoch. */
156 /** Change time. Measured in seconds since epoch. */
159 * Blocks allocated to this cl_object on the server file system.
161 * \todo XXX An interface for block size is needed.
165 * User identifier for quota purposes.
169 * Group identifier for quota purposes.
173 /* nlink of the directory */
176 /* Project identifier for quota purpose. */
181 * Fields in cl_attr that are being set.
196 * Sub-class of lu_object with methods common for objects on the client
199 * cl_object: represents a regular file system object, both a file and a
200 * stripe. cl_object is based on lu_object: it is identified by a fid,
201 * layered, cached, hashed, and lrued. Important distinction with the server
202 * side, where md_object and dt_object are used, is that cl_object "fans out"
203 * at the lov/sns level: depending on the file layout, single file is
204 * represented as a set of "sub-objects" (stripes). At the implementation
205 * level, struct lov_object contains an array of cl_objects. Each sub-object
206 * is a full-fledged cl_object, having its fid, living in the lru and hash
209 * This leads to the next important difference with the server side: on the
210 * client, it's quite usual to have objects with the different sequence of
211 * layers. For example, typical top-object is composed of the following
217 * whereas its sub-objects are composed of
222 * layers. Here "lovsub" is a mostly dummy layer, whose purpose is to keep
223 * track of the object-subobject relationship.
225 * Sub-objects are not cached independently: when top-object is about to
226 * be discarded from the memory, all its sub-objects are torn-down and
229 * \see vvp_object, lov_object, lovsub_object, osc_object
233 struct lu_object co_lu;
234 /** per-object-layer operations */
235 const struct cl_object_operations *co_ops;
236 /** offset of page slice in cl_page buffer */
241 * Description of the client object configuration. This is used for the
242 * creation of a new client object that is identified by a more state than
245 struct cl_object_conf {
247 struct lu_object_conf coc_lu;
250 * Object layout. This is consumed by lov.
252 struct lu_buf coc_layout;
254 * Description of particular stripe location in the
255 * cluster. This is consumed by osc.
257 struct lov_oinfo *coc_oinfo;
260 * VFS inode. This is consumed by vvp.
262 struct inode *coc_inode;
264 * Layout lock handle.
266 struct ldlm_lock *coc_lock;
268 * Operation to handle layout, OBJECT_CONF_XYZ.
274 /** configure layout, set up a new stripe, must be called while
275 * holding layout lock. */
277 /** invalidate the current stripe configuration due to losing
279 OBJECT_CONF_INVALIDATE = 1,
280 /** wait for old layout to go away so that new layout can be
286 CL_LAYOUT_GEN_NONE = (u32)-2, /* layout lock was cancelled */
287 CL_LAYOUT_GEN_EMPTY = (u32)-1, /* for empty layout */
291 /** the buffer to return the layout in lov_mds_md format. */
292 struct lu_buf cl_buf;
293 /** size of layout in lov_mds_md format. */
295 /** size of DoM component if exists or zero otherwise */
296 u64 cl_dom_comp_size;
297 /** Layout generation. */
299 /** whether layout is a composite one */
300 bool cl_is_composite;
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);
905 * Optional debugging helper. Prints given page slice.
907 * \see cl_page_print()
909 int (*cpo_print)(const struct lu_env *env,
910 const struct cl_page_slice *slice,
911 void *cookie, lu_printer_t p);
920 * Request type dependent vector of operations.
922 * Transfer operations depend on transfer mode (cl_req_type). To avoid
923 * passing transfer mode to each and every of these methods, and to
924 * avoid branching on request type inside of the methods, separate
925 * methods for cl_req_type:CRT_READ and cl_req_type:CRT_WRITE are
926 * provided. That is, method invocation usually looks like
928 * slice->cp_ops.io[req->crq_type].cpo_method(env, slice, ...);
932 * Called when a page is submitted for a transfer as a part of
935 * \return 0 : page is eligible for submission;
936 * \return -EALREADY : skip this page;
937 * \return -ve : error.
939 * \see cl_page_prep()
941 int (*cpo_prep)(const struct lu_env *env,
942 const struct cl_page_slice *slice,
945 * Completion handler. This is guaranteed to be eventually
946 * fired after cl_page_operations::cpo_prep() or
947 * cl_page_operations::cpo_make_ready() call.
949 * This method can be called in a non-blocking context. It is
950 * guaranteed however, that the page involved and its object
951 * are pinned in memory (and, hence, calling cl_page_put() is
954 * \see cl_page_completion()
956 void (*cpo_completion)(const struct lu_env *env,
957 const struct cl_page_slice *slice,
960 * Called when cached page is about to be added to the
961 * ptlrpc request as a part of req formation.
963 * \return 0 : proceed with this page;
964 * \return -EAGAIN : skip this page;
965 * \return -ve : error.
967 * \see cl_page_make_ready()
969 int (*cpo_make_ready)(const struct lu_env *env,
970 const struct cl_page_slice *slice);
973 * Tell transfer engine that only [to, from] part of a page should be
976 * This is used for immediate transfers.
978 * \todo XXX this is not very good interface. It would be much better
979 * if all transfer parameters were supplied as arguments to
980 * cl_io_operations::cio_submit() call, but it is not clear how to do
981 * this for page queues.
983 * \see cl_page_clip()
985 void (*cpo_clip)(const struct lu_env *env,
986 const struct cl_page_slice *slice,
989 * \pre the page was queued for transferring.
990 * \post page is removed from client's pending list, or -EBUSY
991 * is returned if it has already been in transferring.
993 * This is one of seldom page operation which is:
994 * 0. called from top level;
995 * 1. don't have vmpage locked;
996 * 2. every layer should synchronize execution of its ->cpo_cancel()
997 * with completion handlers. Osc uses client obd lock for this
998 * purpose. Based on there is no vvp_page_cancel and
999 * lov_page_cancel(), cpo_cancel is defacto protected by client lock.
1001 * \see osc_page_cancel().
1003 int (*cpo_cancel)(const struct lu_env *env,
1004 const struct cl_page_slice *slice);
1006 * Write out a page by kernel. This is only called by ll_writepage
1009 * \see cl_page_flush()
1011 int (*cpo_flush)(const struct lu_env *env,
1012 const struct cl_page_slice *slice,
1018 * Helper macro, dumping detailed information about \a page into a log.
1020 #define CL_PAGE_DEBUG(mask, env, page, format, ...) \
1022 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1023 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1024 cl_page_print(env, &msgdata, lu_cdebug_printer, page); \
1025 CDEBUG(mask, format , ## __VA_ARGS__); \
1030 * Helper macro, dumping shorter information about \a page into a log.
1032 #define CL_PAGE_HEADER(mask, env, page, format, ...) \
1034 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1035 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1036 cl_page_header_print(env, &msgdata, lu_cdebug_printer, page); \
1037 CDEBUG(mask, format , ## __VA_ARGS__); \
1041 static inline struct page *cl_page_vmpage(const struct cl_page *page)
1043 LASSERT(page->cp_vmpage != NULL);
1044 return page->cp_vmpage;
1048 * Check if a cl_page is in use.
1050 * Client cache holds a refcount, this refcount will be dropped when
1051 * the page is taken out of cache, see vvp_page_delete().
1053 static inline bool __page_in_use(const struct cl_page *page, int refc)
1055 return (atomic_read(&page->cp_ref) > refc + 1);
1059 * Caller itself holds a refcount of cl_page.
1061 #define cl_page_in_use(pg) __page_in_use(pg, 1)
1063 * Caller doesn't hold a refcount.
1065 #define cl_page_in_use_noref(pg) __page_in_use(pg, 0)
1069 /** \addtogroup cl_lock cl_lock
1073 * Extent locking on the client.
1077 * The locking model of the new client code is built around
1081 * data-type representing an extent lock on a regular file. cl_lock is a
1082 * layered object (much like cl_object and cl_page), it consists of a header
1083 * (struct cl_lock) and a list of layers (struct cl_lock_slice), linked to
1084 * cl_lock::cll_layers list through cl_lock_slice::cls_linkage.
1086 * Typical cl_lock consists of one layer:
1088 * - lov_lock (lov specific data).
1090 * lov_lock contains an array of sub-locks. Each of these sub-locks is a
1091 * normal cl_lock: it has a header (struct cl_lock) and a list of layers:
1095 * Each sub-lock is associated with a cl_object (representing stripe
1096 * sub-object or the file to which top-level cl_lock is associated to), and is
1097 * linked into that cl_object::coh_locks. In this respect cl_lock is similar to
1098 * cl_object (that at lov layer also fans out into multiple sub-objects), and
1099 * is different from cl_page, that doesn't fan out (there is usually exactly
1100 * one osc_page for every vvp_page). We shall call vvp-lov portion of the lock
1101 * a "top-lock" and its lovsub-osc portion a "sub-lock".
1105 * cl_lock is a cacheless data container for the requirements of locks to
1106 * complete the IO. cl_lock is created before I/O starts and destroyed when the
1109 * cl_lock depends on LDLM lock to fulfill lock semantics. LDLM lock is attached
1110 * to cl_lock at OSC layer. LDLM lock is still cacheable.
1112 * INTERFACE AND USAGE
1114 * Two major methods are supported for cl_lock: clo_enqueue and clo_cancel. A
1115 * cl_lock is enqueued by cl_lock_request(), which will call clo_enqueue()
1116 * methods for each layer to enqueue the lock. At the LOV layer, if a cl_lock
1117 * consists of multiple sub cl_locks, each sub locks will be enqueued
1118 * correspondingly. At OSC layer, the lock enqueue request will tend to reuse
1119 * cached LDLM lock; otherwise a new LDLM lock will have to be requested from
1122 * cl_lock_cancel() must be called to release a cl_lock after use. clo_cancel()
1123 * method will be called for each layer to release the resource held by this
1124 * lock. At OSC layer, the reference count of LDLM lock, which is held at
1125 * clo_enqueue time, is released.
1127 * LDLM lock can only be canceled if there is no cl_lock using it.
1129 * Overall process of the locking during IO operation is as following:
1131 * - once parameters for IO are setup in cl_io, cl_io_operations::cio_lock()
1132 * is called on each layer. Responsibility of this method is to add locks,
1133 * needed by a given layer into cl_io.ci_lockset.
1135 * - once locks for all layers were collected, they are sorted to avoid
1136 * dead-locks (cl_io_locks_sort()), and enqueued.
1138 * - when all locks are acquired, IO is performed;
1140 * - locks are released after IO is complete.
1142 * Striping introduces major additional complexity into locking. The
1143 * fundamental problem is that it is generally unsafe to actively use (hold)
1144 * two locks on the different OST servers at the same time, as this introduces
1145 * inter-server dependency and can lead to cascading evictions.
1147 * Basic solution is to sub-divide large read/write IOs into smaller pieces so
1148 * that no multi-stripe locks are taken (note that this design abandons POSIX
1149 * read/write semantics). Such pieces ideally can be executed concurrently. At
1150 * the same time, certain types of IO cannot be sub-divived, without
1151 * sacrificing correctness. This includes:
1153 * - O_APPEND write, where [0, EOF] lock has to be taken, to guarantee
1156 * - ftruncate(fd, offset), where [offset, EOF] lock has to be taken.
1158 * Also, in the case of read(fd, buf, count) or write(fd, buf, count), where
1159 * buf is a part of memory mapped Lustre file, a lock or locks protecting buf
1160 * has to be held together with the usual lock on [offset, offset + count].
1162 * Interaction with DLM
1164 * In the expected setup, cl_lock is ultimately backed up by a collection of
1165 * DLM locks (struct ldlm_lock). Association between cl_lock and DLM lock is
1166 * implemented in osc layer, that also matches DLM events (ASTs, cancellation,
1167 * etc.) into cl_lock_operation calls. See struct osc_lock for a more detailed
1168 * description of interaction with DLM.
1174 struct cl_lock_descr {
1175 /** Object this lock is granted for. */
1176 struct cl_object *cld_obj;
1177 /** Index of the first page protected by this lock. */
1179 /** Index of the last page (inclusive) protected by this lock. */
1181 /** Group ID, for group lock */
1184 enum cl_lock_mode cld_mode;
1186 * flags to enqueue lock. A combination of bit-flags from
1187 * enum cl_enq_flags.
1189 __u32 cld_enq_flags;
1192 #define DDESCR "%s(%d):[%lu, %lu]:%x"
1193 #define PDESCR(descr) \
1194 cl_lock_mode_name((descr)->cld_mode), (descr)->cld_mode, \
1195 (descr)->cld_start, (descr)->cld_end, (descr)->cld_enq_flags
1197 const char *cl_lock_mode_name(const enum cl_lock_mode mode);
1200 * Layered client lock.
1203 /** List of slices. Immutable after creation. */
1204 struct list_head cll_layers;
1205 /** lock attribute, extent, cl_object, etc. */
1206 struct cl_lock_descr cll_descr;
1210 * Per-layer part of cl_lock
1212 * \see lov_lock, osc_lock
1214 struct cl_lock_slice {
1215 struct cl_lock *cls_lock;
1216 /** Object slice corresponding to this lock slice. Immutable after
1218 struct cl_object *cls_obj;
1219 const struct cl_lock_operations *cls_ops;
1220 /** Linkage into cl_lock::cll_layers. Immutable after creation. */
1221 struct list_head cls_linkage;
1226 * \see lov_lock_ops, osc_lock_ops
1228 struct cl_lock_operations {
1231 * Attempts to enqueue the lock. Called top-to-bottom.
1233 * \retval 0 this layer has enqueued the lock successfully
1234 * \retval >0 this layer has enqueued the lock, but need to wait on
1235 * @anchor for resources
1236 * \retval -ve failure
1238 * \see lov_lock_enqueue(), osc_lock_enqueue()
1240 int (*clo_enqueue)(const struct lu_env *env,
1241 const struct cl_lock_slice *slice,
1242 struct cl_io *io, struct cl_sync_io *anchor);
1244 * Cancel a lock, release its DLM lock ref, while does not cancel the
1247 void (*clo_cancel)(const struct lu_env *env,
1248 const struct cl_lock_slice *slice);
1251 * Destructor. Frees resources and the slice.
1253 * \see lov_lock_fini(), osc_lock_fini()
1255 void (*clo_fini)(const struct lu_env *env, struct cl_lock_slice *slice);
1257 * Optional debugging helper. Prints given lock slice.
1259 int (*clo_print)(const struct lu_env *env,
1260 void *cookie, lu_printer_t p,
1261 const struct cl_lock_slice *slice);
1264 #define CL_LOCK_DEBUG(mask, env, lock, format, ...) \
1266 if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
1267 LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
1268 cl_lock_print(env, &msgdata, lu_cdebug_printer, lock); \
1269 CDEBUG(mask, format , ## __VA_ARGS__); \
1273 #define CL_LOCK_ASSERT(expr, env, lock) do { \
1277 CL_LOCK_DEBUG(D_ERROR, env, lock, "failed at %s.\n", #expr); \
1283 /** \addtogroup cl_page_list cl_page_list
1284 * Page list used to perform collective operations on a group of pages.
1286 * Pages are added to the list one by one. cl_page_list acquires a reference
1287 * for every page in it. Page list is used to perform collective operations on
1290 * - submit pages for an immediate transfer,
1292 * - own pages on behalf of certain io (waiting for each page in turn),
1296 * When list is finalized, it releases references on all pages it still has.
1298 * \todo XXX concurrency control.
1302 struct cl_page_list {
1304 struct list_head pl_pages;
1305 struct task_struct *pl_owner;
1309 * A 2-queue of pages. A convenience data-type for common use case, 2-queue
1310 * contains an incoming page list and an outgoing page list.
1313 struct cl_page_list c2_qin;
1314 struct cl_page_list c2_qout;
1317 /** @} cl_page_list */
1319 /** \addtogroup cl_io cl_io
1324 * cl_io represents a high level I/O activity like
1325 * read(2)/write(2)/truncate(2) system call, or cancellation of an extent
1328 * cl_io is a layered object, much like cl_{object,page,lock} but with one
1329 * important distinction. We want to minimize number of calls to the allocator
1330 * in the fast path, e.g., in the case of read(2) when everything is cached:
1331 * client already owns the lock over region being read, and data are cached
1332 * due to read-ahead. To avoid allocation of cl_io layers in such situations,
1333 * per-layer io state is stored in the session, associated with the io, see
1334 * struct {vvp,lov,osc}_io for example. Sessions allocation is amortized
1335 * by using free-lists, see cl_env_get().
1337 * There is a small predefined number of possible io types, enumerated in enum
1340 * cl_io is a state machine, that can be advanced concurrently by the multiple
1341 * threads. It is up to these threads to control the concurrency and,
1342 * specifically, to detect when io is done, and its state can be safely
1345 * For read/write io overall execution plan is as following:
1347 * (0) initialize io state through all layers;
1349 * (1) loop: prepare chunk of work to do
1351 * (2) call all layers to collect locks they need to process current chunk
1353 * (3) sort all locks to avoid dead-locks, and acquire them
1355 * (4) process the chunk: call per-page methods
1356 * cl_io_operations::cio_prepare_write(),
1357 * cl_io_operations::cio_commit_write() for write)
1363 * To implement the "parallel IO mode", lov layer creates sub-io's (lazily to
1364 * address allocation efficiency issues mentioned above), and returns with the
1365 * special error condition from per-page method when current sub-io has to
1366 * block. This causes io loop to be repeated, and lov switches to the next
1367 * sub-io in its cl_io_operations::cio_iter_init() implementation.
1372 /** read system call */
1374 /** write system call */
1376 /** truncate, utime system calls */
1378 /** get data version */
1381 * page fault handling
1385 * fsync system call handling
1386 * To write out a range of file
1390 * glimpse. An io context to acquire glimpse lock.
1394 * Miscellaneous io. This is used for occasional io activity that
1395 * doesn't fit into other types. Currently this is used for:
1397 * - cancellation of an extent lock. This io exists as a context
1398 * to write dirty pages from under the lock being canceled back
1401 * - VM induced page write-out. An io context for writing page out
1402 * for memory cleansing;
1404 * - grouplock. An io context to acquire group lock.
1406 * CIT_MISC io is used simply as a context in which locks and pages
1407 * are manipulated. Such io has no internal "process", that is,
1408 * cl_io_loop() is never called for it.
1413 * To give advice about access of a file
1420 * States of cl_io state machine
1423 /** Not initialized. */
1427 /** IO iteration started. */
1431 /** Actual IO is in progress. */
1433 /** IO for the current iteration finished. */
1435 /** Locks released. */
1437 /** Iteration completed. */
1439 /** cl_io finalized. */
1444 * IO state private for a layer.
1446 * This is usually embedded into layer session data, rather than allocated
1449 * \see vvp_io, lov_io, osc_io
1451 struct cl_io_slice {
1452 struct cl_io *cis_io;
1453 /** corresponding object slice. Immutable after creation. */
1454 struct cl_object *cis_obj;
1455 /** io operations. Immutable after creation. */
1456 const struct cl_io_operations *cis_iop;
1458 * linkage into a list of all slices for a given cl_io, hanging off
1459 * cl_io::ci_layers. Immutable after creation.
1461 struct list_head cis_linkage;
1464 typedef void (*cl_commit_cbt)(const struct lu_env *, struct cl_io *,
1467 struct cl_read_ahead {
1468 /* Maximum page index the readahead window will end.
1469 * This is determined DLM lock coverage, RPC and stripe boundary.
1470 * cra_end is included. */
1472 /* optimal RPC size for this read, by pages */
1473 unsigned long cra_rpc_size;
1474 /* Release callback. If readahead holds resources underneath, this
1475 * function should be called to release it. */
1476 void (*cra_release)(const struct lu_env *env, void *cbdata);
1477 /* Callback data for cra_release routine */
1481 static inline void cl_read_ahead_release(const struct lu_env *env,
1482 struct cl_read_ahead *ra)
1484 if (ra->cra_release != NULL)
1485 ra->cra_release(env, ra->cra_cbdata);
1486 memset(ra, 0, sizeof(*ra));
1491 * Per-layer io operations.
1492 * \see vvp_io_ops, lov_io_ops, lovsub_io_ops, osc_io_ops
1494 struct cl_io_operations {
1496 * Vector of io state transition methods for every io type.
1498 * \see cl_page_operations::io
1502 * Prepare io iteration at a given layer.
1504 * Called top-to-bottom at the beginning of each iteration of
1505 * "io loop" (if it makes sense for this type of io). Here
1506 * layer selects what work it will do during this iteration.
1508 * \see cl_io_operations::cio_iter_fini()
1510 int (*cio_iter_init) (const struct lu_env *env,
1511 const struct cl_io_slice *slice);
1513 * Finalize io iteration.
1515 * Called bottom-to-top at the end of each iteration of "io
1516 * loop". Here layers can decide whether IO has to be
1519 * \see cl_io_operations::cio_iter_init()
1521 void (*cio_iter_fini) (const struct lu_env *env,
1522 const struct cl_io_slice *slice);
1524 * Collect locks for the current iteration of io.
1526 * Called top-to-bottom to collect all locks necessary for
1527 * this iteration. This methods shouldn't actually enqueue
1528 * anything, instead it should post a lock through
1529 * cl_io_lock_add(). Once all locks are collected, they are
1530 * sorted and enqueued in the proper order.
1532 int (*cio_lock) (const struct lu_env *env,
1533 const struct cl_io_slice *slice);
1535 * Finalize unlocking.
1537 * Called bottom-to-top to finish layer specific unlocking
1538 * functionality, after generic code released all locks
1539 * acquired by cl_io_operations::cio_lock().
1541 void (*cio_unlock)(const struct lu_env *env,
1542 const struct cl_io_slice *slice);
1544 * Start io iteration.
1546 * Once all locks are acquired, called top-to-bottom to
1547 * commence actual IO. In the current implementation,
1548 * top-level vvp_io_{read,write}_start() does all the work
1549 * synchronously by calling generic_file_*(), so other layers
1550 * are called when everything is done.
1552 int (*cio_start)(const struct lu_env *env,
1553 const struct cl_io_slice *slice);
1555 * Called top-to-bottom at the end of io loop. Here layer
1556 * might wait for an unfinished asynchronous io.
1558 void (*cio_end) (const struct lu_env *env,
1559 const struct cl_io_slice *slice);
1561 * Called bottom-to-top to notify layers that read/write IO
1562 * iteration finished, with \a nob bytes transferred.
1564 void (*cio_advance)(const struct lu_env *env,
1565 const struct cl_io_slice *slice,
1568 * Called once per io, bottom-to-top to release io resources.
1570 void (*cio_fini) (const struct lu_env *env,
1571 const struct cl_io_slice *slice);
1575 * Submit pages from \a queue->c2_qin for IO, and move
1576 * successfully submitted pages into \a queue->c2_qout. Return
1577 * non-zero if failed to submit even the single page. If
1578 * submission failed after some pages were moved into \a
1579 * queue->c2_qout, completion callback with non-zero ioret is
1582 int (*cio_submit)(const struct lu_env *env,
1583 const struct cl_io_slice *slice,
1584 enum cl_req_type crt,
1585 struct cl_2queue *queue);
1587 * Queue async page for write.
1588 * The difference between cio_submit and cio_queue is that
1589 * cio_submit is for urgent request.
1591 int (*cio_commit_async)(const struct lu_env *env,
1592 const struct cl_io_slice *slice,
1593 struct cl_page_list *queue, int from, int to,
1596 * Decide maximum read ahead extent
1598 * \pre io->ci_type == CIT_READ
1600 int (*cio_read_ahead)(const struct lu_env *env,
1601 const struct cl_io_slice *slice,
1602 pgoff_t start, struct cl_read_ahead *ra);
1604 * Optional debugging helper. Print given io slice.
1606 int (*cio_print)(const struct lu_env *env, void *cookie,
1607 lu_printer_t p, const struct cl_io_slice *slice);
1611 * Flags to lock enqueue procedure.
1616 * instruct server to not block, if conflicting lock is found. Instead
1617 * -EWOULDBLOCK is returned immediately.
1619 CEF_NONBLOCK = 0x00000001,
1621 * Tell lower layers this is a glimpse request, translated to
1622 * LDLM_FL_HAS_INTENT at LDLM layer.
1624 * Also, because glimpse locks never block other locks, we count this
1625 * as automatically compatible with other osc locks.
1626 * (see osc_lock_compatible)
1628 CEF_GLIMPSE = 0x00000002,
1630 * tell the server to instruct (though a flag in the blocking ast) an
1631 * owner of the conflicting lock, that it can drop dirty pages
1632 * protected by this lock, without sending them to the server.
1634 CEF_DISCARD_DATA = 0x00000004,
1636 * tell the sub layers that it must be a `real' lock. This is used for
1637 * mmapped-buffer locks, glimpse locks, manually requested locks
1638 * (LU_LADVISE_LOCKAHEAD) that must never be converted into lockless
1641 * \see vvp_mmap_locks(), cl_glimpse_lock, cl_request_lock().
1643 CEF_MUST = 0x00000008,
1645 * tell the sub layers that never request a `real' lock. This flag is
1646 * not used currently.
1648 * cl_io::ci_lockreq and CEF_{MUST,NEVER} flags specify lockless
1649 * conversion policy: ci_lockreq describes generic information of lock
1650 * requirement for this IO, especially for locks which belong to the
1651 * object doing IO; however, lock itself may have precise requirements
1652 * that are described by the enqueue flags.
1654 CEF_NEVER = 0x00000010,
1656 * tell the dlm layer this is a speculative lock request
1657 * speculative lock requests are locks which are not requested as part
1658 * of an I/O operation. Instead, they are requested because we expect
1659 * to use them in the future. They are requested asynchronously at the
1662 * Currently used for asynchronous glimpse locks and manually requested
1663 * locks (LU_LADVISE_LOCKAHEAD).
1665 CEF_SPECULATIVE = 0x00000020,
1667 * enqueue a lock to test DLM lock existence.
1669 CEF_PEEK = 0x00000040,
1671 * Lock match only. Used by group lock in I/O as group lock
1672 * is known to exist.
1674 CEF_LOCK_MATCH = 0x00000080,
1676 * tell the DLM layer to lock only the requested range
1678 CEF_LOCK_NO_EXPAND = 0x00000100,
1680 * mask of enq_flags.
1682 CEF_MASK = 0x000001ff,
1686 * Link between lock and io. Intermediate structure is needed, because the
1687 * same lock can be part of multiple io's simultaneously.
1689 struct cl_io_lock_link {
1690 /** linkage into one of cl_lockset lists. */
1691 struct list_head cill_linkage;
1692 struct cl_lock cill_lock;
1693 /** optional destructor */
1694 void (*cill_fini)(const struct lu_env *env,
1695 struct cl_io_lock_link *link);
1697 #define cill_descr cill_lock.cll_descr
1700 * Lock-set represents a collection of locks, that io needs at a
1701 * time. Generally speaking, client tries to avoid holding multiple locks when
1704 * - holding extent locks over multiple ost's introduces the danger of
1705 * "cascading timeouts";
1707 * - holding multiple locks over the same ost is still dead-lock prone,
1708 * see comment in osc_lock_enqueue(),
1710 * but there are certain situations where this is unavoidable:
1712 * - O_APPEND writes have to take [0, EOF] lock for correctness;
1714 * - truncate has to take [new-size, EOF] lock for correctness;
1716 * - SNS has to take locks across full stripe for correctness;
1718 * - in the case when user level buffer, supplied to {read,write}(file0),
1719 * is a part of a memory mapped lustre file, client has to take a dlm
1720 * locks on file0, and all files that back up the buffer (or a part of
1721 * the buffer, that is being processed in the current chunk, in any
1722 * case, there are situations where at least 2 locks are necessary).
1724 * In such cases we at least try to take locks in the same consistent
1725 * order. To this end, all locks are first collected, then sorted, and then
1729 /** locks to be acquired. */
1730 struct list_head cls_todo;
1731 /** locks acquired. */
1732 struct list_head cls_done;
1736 * Lock requirements(demand) for IO. It should be cl_io_lock_req,
1737 * but 'req' is always to be thought as 'request' :-)
1739 enum cl_io_lock_dmd {
1740 /** Always lock data (e.g., O_APPEND). */
1742 /** Layers are free to decide between local and global locking. */
1744 /** Never lock: there is no cache (e.g., liblustre). */
1748 enum cl_fsync_mode {
1749 /** start writeback, do not wait for them to finish */
1751 /** start writeback and wait for them to finish */
1753 /** discard all of dirty pages in a specific file range */
1754 CL_FSYNC_DISCARD = 2,
1755 /** start writeback and make sure they have reached storage before
1756 * return. OST_SYNC RPC must be issued and finished */
1760 struct cl_io_range {
1766 struct cl_io_pt *cip_next;
1767 struct cfs_ptask cip_task;
1768 struct kiocb cip_iocb;
1769 struct iov_iter cip_iter;
1770 struct file *cip_file;
1771 enum cl_io_type cip_iot;
1772 unsigned int cip_need_restart:1;
1781 * cl_io is shared by all threads participating in this IO (in current
1782 * implementation only one thread advances IO, but parallel IO design and
1783 * concurrent copy_*_user() require multiple threads acting on the same IO. It
1784 * is up to these threads to serialize their activities, including updates to
1785 * mutable cl_io fields.
1788 /** type of this IO. Immutable after creation. */
1789 enum cl_io_type ci_type;
1790 /** current state of cl_io state machine. */
1791 enum cl_io_state ci_state;
1792 /** main object this io is against. Immutable after creation. */
1793 struct cl_object *ci_obj;
1795 * Upper layer io, of which this io is a part of. Immutable after
1798 struct cl_io *ci_parent;
1799 /** List of slices. Immutable after creation. */
1800 struct list_head ci_layers;
1801 /** list of locks (to be) acquired by this io. */
1802 struct cl_lockset ci_lockset;
1803 /** lock requirements, this is just a help info for sublayers. */
1804 enum cl_io_lock_dmd ci_lockreq;
1805 /** layout version when this IO occurs */
1806 __u32 ci_layout_version;
1809 struct iov_iter rw_iter;
1810 struct kiocb rw_iocb;
1811 struct cl_io_range rw_range;
1812 struct file *rw_file;
1813 unsigned int rw_nonblock:1,
1816 int (*rw_ptask)(struct cfs_ptask *ptask);
1818 struct cl_setattr_io {
1819 struct ost_lvb sa_attr;
1820 unsigned int sa_attr_flags;
1821 unsigned int sa_valid;
1822 int sa_stripe_index;
1823 struct ost_layout sa_layout;
1824 const struct lu_fid *sa_parent_fid;
1826 struct cl_data_version_io {
1827 u64 dv_data_version;
1828 u32 dv_layout_version;
1831 struct cl_fault_io {
1832 /** page index within file. */
1834 /** bytes valid byte on a faulted page. */
1836 /** writable page? for nopage() only */
1838 /** page of an executable? */
1840 /** page_mkwrite() */
1842 /** resulting page */
1843 struct cl_page *ft_page;
1845 struct cl_fsync_io {
1848 /** file system level fid */
1849 struct lu_fid *fi_fid;
1850 enum cl_fsync_mode fi_mode;
1851 /* how many pages were written/discarded */
1852 unsigned int fi_nr_written;
1854 struct cl_ladvise_io {
1857 /** file system level fid */
1858 struct lu_fid *li_fid;
1859 enum lu_ladvise_type li_advice;
1863 struct cl_2queue ci_queue;
1866 unsigned int ci_continue:1,
1868 * This io has held grouplock, to inform sublayers that
1869 * don't do lockless i/o.
1873 * The whole IO need to be restarted because layout has been changed
1877 * to not refresh layout - the IO issuer knows that the layout won't
1878 * change(page operations, layout change causes all page to be
1879 * discarded), or it doesn't matter if it changes(sync).
1883 * Need MDS intervention to complete a write.
1884 * Write intent is required for the following cases:
1885 * 1. component being written is not initialized, or
1886 * 2. the mirrored files are NOT in WRITE_PENDING state.
1888 ci_need_write_intent:1,
1890 * Check if layout changed after the IO finishes. Mainly for HSM
1891 * requirement. If IO occurs to openning files, it doesn't need to
1892 * verify layout because HSM won't release openning files.
1893 * Right now, only two opertaions need to verify layout: glimpse
1898 * file is released, restore has to to be triggered by vvp layer
1900 ci_restore_needed:1,
1905 /** Set to 1 if parallel execution is allowed for current I/O? */
1907 /* Tell sublayers not to expand LDLM locks requested for this IO */
1908 ci_lock_no_expand:1,
1910 * Set if non-delay RPC should be used for this IO.
1912 * If this file has multiple mirrors, and if the OSTs of the current
1913 * mirror is inaccessible, non-delay RPC would error out quickly so
1914 * that the upper layer can try to access the next mirror.
1918 * How many times the read has retried before this one.
1919 * Set by the top level and consumed by the LOV.
1921 unsigned ci_ndelay_tried;
1923 * Designated mirror index for this I/O.
1925 unsigned ci_designated_mirror;
1927 * Number of pages owned by this IO. For invariant checking.
1929 unsigned ci_owned_nr;
1931 * Range of write intent. Valid if ci_need_write_intent is set.
1933 struct lu_extent ci_write_intent;
1939 * Per-transfer attributes.
1941 struct cl_req_attr {
1942 enum cl_req_type cra_type;
1944 struct cl_page *cra_page;
1945 /** Generic attributes for the server consumption. */
1946 struct obdo *cra_oa;
1948 char cra_jobid[LUSTRE_JOBID_SIZE];
1951 enum cache_stats_item {
1952 /** how many cache lookups were performed */
1954 /** how many times cache lookup resulted in a hit */
1956 /** how many entities are in the cache right now */
1958 /** how many entities in the cache are actively used (and cannot be
1959 * evicted) right now */
1961 /** how many entities were created at all */
1966 #define CS_NAMES { "lookup", "hit", "total", "busy", "create" }
1969 * Stats for a generic cache (similar to inode, lu_object, etc. caches).
1971 struct cache_stats {
1972 const char *cs_name;
1973 atomic_t cs_stats[CS_NR];
1976 /** These are not exported so far */
1977 void cache_stats_init (struct cache_stats *cs, const char *name);
1980 * Client-side site. This represents particular client stack. "Global"
1981 * variables should (directly or indirectly) be added here to allow multiple
1982 * clients to co-exist in the single address space.
1985 struct lu_site cs_lu;
1987 * Statistical counters. Atomics do not scale, something better like
1988 * per-cpu counters is needed.
1990 * These are exported as /proc/fs/lustre/llite/.../site
1992 * When interpreting keep in mind that both sub-locks (and sub-pages)
1993 * and top-locks (and top-pages) are accounted here.
1995 struct cache_stats cs_pages;
1996 atomic_t cs_pages_state[CPS_NR];
1999 int cl_site_init(struct cl_site *s, struct cl_device *top);
2000 void cl_site_fini(struct cl_site *s);
2001 void cl_stack_fini(const struct lu_env *env, struct cl_device *cl);
2004 * Output client site statistical counters into a buffer. Suitable for
2005 * ll_rd_*()-style functions.
2007 int cl_site_stats_print(const struct cl_site *site, struct seq_file *m);
2012 * Type conversion and accessory functions.
2016 static inline struct cl_site *lu2cl_site(const struct lu_site *site)
2018 return container_of(site, struct cl_site, cs_lu);
2021 static inline struct cl_device *lu2cl_dev(const struct lu_device *d)
2023 LASSERT(d == NULL || IS_ERR(d) || lu_device_is_cl(d));
2024 return container_of0(d, struct cl_device, cd_lu_dev);
2027 static inline struct lu_device *cl2lu_dev(struct cl_device *d)
2029 return &d->cd_lu_dev;
2032 static inline struct cl_object *lu2cl(const struct lu_object *o)
2034 LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->lo_dev));
2035 return container_of0(o, struct cl_object, co_lu);
2038 static inline const struct cl_object_conf *
2039 lu2cl_conf(const struct lu_object_conf *conf)
2041 return container_of0(conf, struct cl_object_conf, coc_lu);
2044 static inline struct cl_object *cl_object_next(const struct cl_object *obj)
2046 return obj ? lu2cl(lu_object_next(&obj->co_lu)) : NULL;
2049 static inline struct cl_object_header *luh2coh(const struct lu_object_header *h)
2051 return container_of0(h, struct cl_object_header, coh_lu);
2054 static inline struct cl_site *cl_object_site(const struct cl_object *obj)
2056 return lu2cl_site(obj->co_lu.lo_dev->ld_site);
2060 struct cl_object_header *cl_object_header(const struct cl_object *obj)
2062 return luh2coh(obj->co_lu.lo_header);
2065 static inline int cl_device_init(struct cl_device *d, struct lu_device_type *t)
2067 return lu_device_init(&d->cd_lu_dev, t);
2070 static inline void cl_device_fini(struct cl_device *d)
2072 lu_device_fini(&d->cd_lu_dev);
2075 void cl_page_slice_add(struct cl_page *page, struct cl_page_slice *slice,
2076 struct cl_object *obj, pgoff_t index,
2077 const struct cl_page_operations *ops);
2078 void cl_lock_slice_add(struct cl_lock *lock, struct cl_lock_slice *slice,
2079 struct cl_object *obj,
2080 const struct cl_lock_operations *ops);
2081 void cl_io_slice_add(struct cl_io *io, struct cl_io_slice *slice,
2082 struct cl_object *obj, const struct cl_io_operations *ops);
2085 /** \defgroup cl_object cl_object
2087 struct cl_object *cl_object_top (struct cl_object *o);
2088 struct cl_object *cl_object_find(const struct lu_env *env, struct cl_device *cd,
2089 const struct lu_fid *fid,
2090 const struct cl_object_conf *c);
2092 int cl_object_header_init(struct cl_object_header *h);
2093 void cl_object_header_fini(struct cl_object_header *h);
2094 void cl_object_put (const struct lu_env *env, struct cl_object *o);
2095 void cl_object_get (struct cl_object *o);
2096 void cl_object_attr_lock (struct cl_object *o);
2097 void cl_object_attr_unlock(struct cl_object *o);
2098 int cl_object_attr_get(const struct lu_env *env, struct cl_object *obj,
2099 struct cl_attr *attr);
2100 int cl_object_attr_update(const struct lu_env *env, struct cl_object *obj,
2101 const struct cl_attr *attr, unsigned valid);
2102 int cl_object_glimpse (const struct lu_env *env, struct cl_object *obj,
2103 struct ost_lvb *lvb);
2104 int cl_conf_set (const struct lu_env *env, struct cl_object *obj,
2105 const struct cl_object_conf *conf);
2106 int cl_object_prune (const struct lu_env *env, struct cl_object *obj);
2107 void cl_object_kill (const struct lu_env *env, struct cl_object *obj);
2108 int cl_object_getstripe(const struct lu_env *env, struct cl_object *obj,
2109 struct lov_user_md __user *lum, size_t size);
2110 int cl_object_fiemap(const struct lu_env *env, struct cl_object *obj,
2111 struct ll_fiemap_info_key *fmkey, struct fiemap *fiemap,
2113 int cl_object_layout_get(const struct lu_env *env, struct cl_object *obj,
2114 struct cl_layout *cl);
2115 loff_t cl_object_maxbytes(struct cl_object *obj);
2118 * Returns true, iff \a o0 and \a o1 are slices of the same object.
2120 static inline int cl_object_same(struct cl_object *o0, struct cl_object *o1)
2122 return cl_object_header(o0) == cl_object_header(o1);
2125 static inline void cl_object_page_init(struct cl_object *clob, int size)
2127 clob->co_slice_off = cl_object_header(clob)->coh_page_bufsize;
2128 cl_object_header(clob)->coh_page_bufsize += cfs_size_round(size);
2129 WARN_ON(cl_object_header(clob)->coh_page_bufsize > 512);
2132 static inline void *cl_object_page_slice(struct cl_object *clob,
2133 struct cl_page *page)
2135 return (void *)((char *)page + clob->co_slice_off);
2139 * Return refcount of cl_object.
2141 static inline int cl_object_refc(struct cl_object *clob)
2143 struct lu_object_header *header = clob->co_lu.lo_header;
2144 return atomic_read(&header->loh_ref);
2149 /** \defgroup cl_page cl_page
2157 /* callback of cl_page_gang_lookup() */
2159 struct cl_page *cl_page_find (const struct lu_env *env,
2160 struct cl_object *obj,
2161 pgoff_t idx, struct page *vmpage,
2162 enum cl_page_type type);
2163 struct cl_page *cl_page_alloc (const struct lu_env *env,
2164 struct cl_object *o, pgoff_t ind,
2165 struct page *vmpage,
2166 enum cl_page_type type);
2167 void cl_page_get (struct cl_page *page);
2168 void cl_page_put (const struct lu_env *env,
2169 struct cl_page *page);
2170 void cl_page_print (const struct lu_env *env, void *cookie,
2171 lu_printer_t printer,
2172 const struct cl_page *pg);
2173 void cl_page_header_print(const struct lu_env *env, void *cookie,
2174 lu_printer_t printer,
2175 const struct cl_page *pg);
2176 struct cl_page *cl_vmpage_page (struct page *vmpage, struct cl_object *obj);
2177 struct cl_page *cl_page_top (struct cl_page *page);
2179 const struct cl_page_slice *cl_page_at(const struct cl_page *page,
2180 const struct lu_device_type *dtype);
2185 * Functions dealing with the ownership of page by io.
2189 int cl_page_own (const struct lu_env *env,
2190 struct cl_io *io, struct cl_page *page);
2191 int cl_page_own_try (const struct lu_env *env,
2192 struct cl_io *io, struct cl_page *page);
2193 void cl_page_assume (const struct lu_env *env,
2194 struct cl_io *io, struct cl_page *page);
2195 void cl_page_unassume (const struct lu_env *env,
2196 struct cl_io *io, struct cl_page *pg);
2197 void cl_page_disown (const struct lu_env *env,
2198 struct cl_io *io, struct cl_page *page);
2199 int cl_page_is_owned (const struct cl_page *pg, const struct cl_io *io);
2206 * Functions dealing with the preparation of a page for a transfer, and
2207 * tracking transfer state.
2210 int cl_page_prep (const struct lu_env *env, struct cl_io *io,
2211 struct cl_page *pg, enum cl_req_type crt);
2212 void cl_page_completion (const struct lu_env *env,
2213 struct cl_page *pg, enum cl_req_type crt, int ioret);
2214 int cl_page_make_ready (const struct lu_env *env, struct cl_page *pg,
2215 enum cl_req_type crt);
2216 int cl_page_cache_add (const struct lu_env *env, struct cl_io *io,
2217 struct cl_page *pg, enum cl_req_type crt);
2218 void cl_page_clip (const struct lu_env *env, struct cl_page *pg,
2220 int cl_page_cancel (const struct lu_env *env, struct cl_page *page);
2221 int cl_page_flush (const struct lu_env *env, struct cl_io *io,
2222 struct cl_page *pg);
2228 * \name helper routines
2229 * Functions to discard, delete and export a cl_page.
2232 void cl_page_discard(const struct lu_env *env, struct cl_io *io,
2233 struct cl_page *pg);
2234 void cl_page_delete(const struct lu_env *env, struct cl_page *pg);
2235 int cl_page_is_vmlocked(const struct lu_env *env,
2236 const struct cl_page *pg);
2237 void cl_page_touch(const struct lu_env *env, const struct cl_page *pg,
2239 void cl_page_export(const struct lu_env *env,
2240 struct cl_page *pg, int uptodate);
2241 loff_t cl_offset(const struct cl_object *obj, pgoff_t idx);
2242 pgoff_t cl_index(const struct cl_object *obj, loff_t offset);
2243 size_t cl_page_size(const struct cl_object *obj);
2245 void cl_lock_print(const struct lu_env *env, void *cookie,
2246 lu_printer_t printer, const struct cl_lock *lock);
2247 void cl_lock_descr_print(const struct lu_env *env, void *cookie,
2248 lu_printer_t printer,
2249 const struct cl_lock_descr *descr);
2253 * Data structure managing a client's cached pages. A count of
2254 * "unstable" pages is maintained, and an LRU of clean pages is
2255 * maintained. "unstable" pages are pages pinned by the ptlrpc
2256 * layer for recovery purposes.
2258 struct cl_client_cache {
2260 * # of client cache refcount
2261 * # of users (OSCs) + 2 (held by llite and lov)
2265 * # of threads are doing shrinking
2267 unsigned int ccc_lru_shrinkers;
2269 * # of LRU entries available
2271 atomic_long_t ccc_lru_left;
2273 * List of entities(OSCs) for this LRU cache
2275 struct list_head ccc_lru;
2277 * Max # of LRU entries
2279 unsigned long ccc_lru_max;
2281 * Lock to protect ccc_lru list
2283 spinlock_t ccc_lru_lock;
2285 * Set if unstable check is enabled
2287 unsigned int ccc_unstable_check:1;
2289 * # of unstable pages for this mount point
2291 atomic_long_t ccc_unstable_nr;
2293 * Waitq for awaiting unstable pages to reach zero.
2294 * Used at umounting time and signaled on BRW commit
2296 wait_queue_head_t ccc_unstable_waitq;
2299 * cl_cache functions
2301 struct cl_client_cache *cl_cache_init(unsigned long lru_page_max);
2302 void cl_cache_incref(struct cl_client_cache *cache);
2303 void cl_cache_decref(struct cl_client_cache *cache);
2307 /** \defgroup cl_lock cl_lock
2309 int cl_lock_request(const struct lu_env *env, struct cl_io *io,
2310 struct cl_lock *lock);
2311 int cl_lock_init(const struct lu_env *env, struct cl_lock *lock,
2312 const struct cl_io *io);
2313 void cl_lock_fini(const struct lu_env *env, struct cl_lock *lock);
2314 const struct cl_lock_slice *cl_lock_at(const struct cl_lock *lock,
2315 const struct lu_device_type *dtype);
2316 void cl_lock_release(const struct lu_env *env, struct cl_lock *lock);
2318 int cl_lock_enqueue(const struct lu_env *env, struct cl_io *io,
2319 struct cl_lock *lock, struct cl_sync_io *anchor);
2320 void cl_lock_cancel(const struct lu_env *env, struct cl_lock *lock);
2324 /** \defgroup cl_io cl_io
2327 int cl_io_init (const struct lu_env *env, struct cl_io *io,
2328 enum cl_io_type iot, struct cl_object *obj);
2329 int cl_io_sub_init (const struct lu_env *env, struct cl_io *io,
2330 enum cl_io_type iot, struct cl_object *obj);
2331 int cl_io_rw_init (const struct lu_env *env, struct cl_io *io,
2332 enum cl_io_type iot, loff_t pos, size_t count);
2333 int cl_io_loop (const struct lu_env *env, struct cl_io *io);
2335 void cl_io_fini (const struct lu_env *env, struct cl_io *io);
2336 int cl_io_iter_init (const struct lu_env *env, struct cl_io *io);
2337 void cl_io_iter_fini (const struct lu_env *env, struct cl_io *io);
2338 int cl_io_lock (const struct lu_env *env, struct cl_io *io);
2339 void cl_io_unlock (const struct lu_env *env, struct cl_io *io);
2340 int cl_io_start (const struct lu_env *env, struct cl_io *io);
2341 void cl_io_end (const struct lu_env *env, struct cl_io *io);
2342 int cl_io_lock_add (const struct lu_env *env, struct cl_io *io,
2343 struct cl_io_lock_link *link);
2344 int cl_io_lock_alloc_add(const struct lu_env *env, struct cl_io *io,
2345 struct cl_lock_descr *descr);
2346 int cl_io_submit_rw (const struct lu_env *env, struct cl_io *io,
2347 enum cl_req_type iot, struct cl_2queue *queue);
2348 int cl_io_submit_sync (const struct lu_env *env, struct cl_io *io,
2349 enum cl_req_type iot, struct cl_2queue *queue,
2351 int cl_io_commit_async (const struct lu_env *env, struct cl_io *io,
2352 struct cl_page_list *queue, int from, int to,
2354 int cl_io_read_ahead (const struct lu_env *env, struct cl_io *io,
2355 pgoff_t start, struct cl_read_ahead *ra);
2356 void cl_io_rw_advance (const struct lu_env *env, struct cl_io *io,
2358 int cl_io_cancel (const struct lu_env *env, struct cl_io *io,
2359 struct cl_page_list *queue);
2362 * True, iff \a io is an O_APPEND write(2).
2364 static inline int cl_io_is_append(const struct cl_io *io)
2366 return io->ci_type == CIT_WRITE && io->u.ci_rw.rw_append;
2369 static inline int cl_io_is_sync_write(const struct cl_io *io)
2371 return io->ci_type == CIT_WRITE && io->u.ci_rw.rw_sync;
2374 static inline int cl_io_is_mkwrite(const struct cl_io *io)
2376 return io->ci_type == CIT_FAULT && io->u.ci_fault.ft_mkwrite;
2380 * True, iff \a io is a truncate(2).
2382 static inline int cl_io_is_trunc(const struct cl_io *io)
2384 return io->ci_type == CIT_SETATTR &&
2385 (io->u.ci_setattr.sa_valid & ATTR_SIZE);
2388 struct cl_io *cl_io_top(struct cl_io *io);
2390 void cl_io_print(const struct lu_env *env, void *cookie,
2391 lu_printer_t printer, const struct cl_io *io);
2393 #define CL_IO_SLICE_CLEAN(foo_io, base) \
2395 typeof(foo_io) __foo_io = (foo_io); \
2397 memset(&__foo_io->base, 0, \
2398 sizeof(*__foo_io) - offsetof(typeof(*__foo_io), base)); \
2403 /** \defgroup cl_page_list cl_page_list
2407 * Last page in the page list.
2409 static inline struct cl_page *cl_page_list_last(struct cl_page_list *plist)
2411 LASSERT(plist->pl_nr > 0);
2412 return list_entry(plist->pl_pages.prev, struct cl_page, cp_batch);
2415 static inline struct cl_page *cl_page_list_first(struct cl_page_list *plist)
2417 LASSERT(plist->pl_nr > 0);
2418 return list_entry(plist->pl_pages.next, struct cl_page, cp_batch);
2422 * Iterate over pages in a page list.
2424 #define cl_page_list_for_each(page, list) \
2425 list_for_each_entry((page), &(list)->pl_pages, cp_batch)
2428 * Iterate over pages in a page list, taking possible removals into account.
2430 #define cl_page_list_for_each_safe(page, temp, list) \
2431 list_for_each_entry_safe((page), (temp), &(list)->pl_pages, cp_batch)
2433 void cl_page_list_init (struct cl_page_list *plist);
2434 void cl_page_list_add (struct cl_page_list *plist, struct cl_page *page);
2435 void cl_page_list_move (struct cl_page_list *dst, struct cl_page_list *src,
2436 struct cl_page *page);
2437 void cl_page_list_move_head(struct cl_page_list *dst, struct cl_page_list *src,
2438 struct cl_page *page);
2439 void cl_page_list_splice (struct cl_page_list *list,
2440 struct cl_page_list *head);
2441 void cl_page_list_del (const struct lu_env *env,
2442 struct cl_page_list *plist, struct cl_page *page);
2443 void cl_page_list_disown (const struct lu_env *env,
2444 struct cl_io *io, struct cl_page_list *plist);
2445 void cl_page_list_assume (const struct lu_env *env,
2446 struct cl_io *io, struct cl_page_list *plist);
2447 void cl_page_list_discard(const struct lu_env *env,
2448 struct cl_io *io, struct cl_page_list *plist);
2449 void cl_page_list_fini (const struct lu_env *env, struct cl_page_list *plist);
2451 void cl_2queue_init (struct cl_2queue *queue);
2452 void cl_2queue_add (struct cl_2queue *queue, struct cl_page *page);
2453 void cl_2queue_disown (const struct lu_env *env,
2454 struct cl_io *io, struct cl_2queue *queue);
2455 void cl_2queue_assume (const struct lu_env *env,
2456 struct cl_io *io, struct cl_2queue *queue);
2457 void cl_2queue_discard (const struct lu_env *env,
2458 struct cl_io *io, struct cl_2queue *queue);
2459 void cl_2queue_fini (const struct lu_env *env, struct cl_2queue *queue);
2460 void cl_2queue_init_page(struct cl_2queue *queue, struct cl_page *page);
2462 /** @} cl_page_list */
2464 void cl_req_attr_set(const struct lu_env *env, struct cl_object *obj,
2465 struct cl_req_attr *attr);
2467 /** \defgroup cl_sync_io cl_sync_io
2471 * Anchor for synchronous transfer. This is allocated on a stack by thread
2472 * doing synchronous transfer, and a pointer to this structure is set up in
2473 * every page submitted for transfer. Transfer completion routine updates
2474 * anchor and wakes up waiting thread when transfer is complete.
2477 /** number of pages yet to be transferred. */
2478 atomic_t csi_sync_nr;
2481 /** barrier of destroy this structure */
2482 atomic_t csi_barrier;
2483 /** completion to be signaled when transfer is complete. */
2484 wait_queue_head_t csi_waitq;
2485 /** callback to invoke when this IO is finished */
2486 void (*csi_end_io)(const struct lu_env *,
2487 struct cl_sync_io *);
2490 void cl_sync_io_init(struct cl_sync_io *anchor, int nr,
2491 void (*end)(const struct lu_env *, struct cl_sync_io *));
2492 int cl_sync_io_wait(const struct lu_env *env, struct cl_sync_io *anchor,
2494 void cl_sync_io_note(const struct lu_env *env, struct cl_sync_io *anchor,
2496 void cl_sync_io_end(const struct lu_env *env, struct cl_sync_io *anchor);
2498 /** @} cl_sync_io */
2500 /** \defgroup cl_env cl_env
2502 * lu_env handling for a client.
2504 * lu_env is an environment within which lustre code executes. Its major part
2505 * is lu_context---a fast memory allocation mechanism that is used to conserve
2506 * precious kernel stack space. Originally lu_env was designed for a server,
2509 * - there is a (mostly) fixed number of threads, and
2511 * - call chains have no non-lustre portions inserted between lustre code.
2513 * On a client both these assumtpion fails, because every user thread can
2514 * potentially execute lustre code as part of a system call, and lustre calls
2515 * into VFS or MM that call back into lustre.
2517 * To deal with that, cl_env wrapper functions implement the following
2520 * - allocation and destruction of environment is amortized by caching no
2521 * longer used environments instead of destroying them;
2523 * \see lu_env, lu_context, lu_context_key
2526 struct lu_env *cl_env_get(__u16 *refcheck);
2527 struct lu_env *cl_env_alloc(__u16 *refcheck, __u32 tags);
2528 void cl_env_put(struct lu_env *env, __u16 *refcheck);
2529 unsigned cl_env_cache_purge(unsigned nr);
2530 struct lu_env *cl_env_percpu_get(void);
2531 void cl_env_percpu_put(struct lu_env *env);
2538 void cl_attr2lvb(struct ost_lvb *lvb, const struct cl_attr *attr);
2539 void cl_lvb2attr(struct cl_attr *attr, const struct ost_lvb *lvb);
2541 struct cl_device *cl_type_setup(const struct lu_env *env, struct lu_site *site,
2542 struct lu_device_type *ldt,
2543 struct lu_device *next);
2546 int cl_global_init(void);
2547 void cl_global_fini(void);
2549 #endif /* _LINUX_CL_OBJECT_H */