/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*- * vim:expandtab:shiftwidth=8:tabstop=8: * * GPL HEADER START * * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 only, * as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License version 2 for more details (a copy is included * in the LICENSE file that accompanied this code). * * You should have received a copy of the GNU General Public License * version 2 along with this program; If not, see * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * * GPL HEADER END */ /* * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved. * Use is subject to license terms. */ /* * This file is part of Lustre, http://www.lustre.org/ * Lustre is a trademark of Sun Microsystems, Inc. */ #ifndef _LUSTRE_CL_OBJECT_H #define _LUSTRE_CL_OBJECT_H /** \defgroup clio clio * * Client objects implement io operations and cache pages. * * Examples: lov and osc are implementations of cl interface. * * Big Theory Statement. * * Layered objects. * * Client implementation is based on the following data-types: * * - cl_object * * - cl_page * * - cl_lock represents an extent lock on an object. * * - cl_io represents high-level i/o activity such as whole read/write * system call, or write-out of pages from under the lock being * canceled. cl_io has sub-ios that can be stopped and resumed * independently, thus achieving high degree of transfer * parallelism. Single cl_io can be advanced forward by * the multiple threads (although in the most usual case of * read/write system call it is associated with the single user * thread, that issued the system call). * * - cl_req represents a collection of pages for a transfer. cl_req is * constructed by req-forming engine that tries to saturate * transport with large and continuous transfers. * * Terminology * * - to avoid confusion high-level I/O operation like read or write system * call is referred to as "an io", whereas low-level I/O operation, like * RPC, is referred to as "a transfer" * * - "generic code" means generic (not file system specific) code in the * hosting environment. "cl-code" means code (mostly in cl_*.c files) that * is not layer specific. * * Locking. * * - i_mutex * - PG_locked * - cl_object_header::coh_page_guard * - cl_object_header::coh_lock_guard * - lu_site::ls_guard * * See the top comment in cl_object.c for the description of overall locking and * reference-counting design. * * See comments below for the description of i/o, page, and dlm-locking * design. * * @{ */ /* * super-class definitions. */ #include #include #ifdef __KERNEL__ # include # include #endif struct inode; struct cl_device; struct cl_device_operations; struct cl_object; struct cl_object_page_operations; struct cl_object_lock_operations; struct cl_page; struct cl_page_slice; struct cl_lock; struct cl_lock_slice; struct cl_lock_operations; struct cl_page_operations; struct cl_io; struct cl_io_slice; struct cl_req; struct cl_req_slice; /** * Operations for each data device in the client stack. * * \see vvp_cl_ops, lov_cl_ops, lovsub_cl_ops, osc_cl_ops */ struct cl_device_operations { /** * Initialize cl_req. This method is called top-to-bottom on all * devices in the stack to get them a chance to allocate layer-private * data, and to attach them to the cl_req by calling * cl_req_slice_add(). * * \see osc_req_init(), lov_req_init(), lovsub_req_init() * \see ccc_req_init() */ int (*cdo_req_init)(const struct lu_env *env, struct cl_device *dev, struct cl_req *req); }; /** * Device in the client stack. * * \see ccc_device, lov_device, lovsub_device, osc_device */ struct cl_device { /** Super-class. */ struct lu_device cd_lu_dev; /** Per-layer operation vector. */ const struct cl_device_operations *cd_ops; }; /** \addtogroup cl_object cl_object * @{ */ /** * "Data attributes" of cl_object. Data attributes can be updated * independently for a sub-object, and top-object's attributes are calculated * from sub-objects' ones. */ struct cl_attr { /** Object size, in bytes */ loff_t cat_size; /** * Known minimal size, in bytes. * * This is only valid when at least one DLM lock is held. */ loff_t cat_kms; /** Modification time. Measured in seconds since epoch. */ time_t cat_mtime; /** Access time. Measured in seconds since epoch. */ time_t cat_atime; /** Change time. Measured in seconds since epoch. */ time_t cat_ctime; /** * Blocks allocated to this cl_object on the server file system. * * \todo XXX An interface for block size is needed. */ __u64 cat_blocks; /** * User identifier for quota purposes. */ uid_t cat_uid; /** * Group identifier for quota purposes. */ gid_t cat_gid; }; /** * Fields in cl_attr that are being set. */ enum cl_attr_valid { CAT_SIZE = 1 << 0, CAT_KMS = 1 << 1, CAT_MTIME = 1 << 3, CAT_ATIME = 1 << 4, CAT_CTIME = 1 << 5, CAT_BLOCKS = 1 << 6, CAT_UID = 1 << 7, CAT_GID = 1 << 8 }; /** * Sub-class of lu_object with methods common for objects on the client * stacks. * * cl_object: represents a regular file system object, both a file and a * stripe. cl_object is based on lu_object: it is identified by a fid, * layered, cached, hashed, and lrued. Important distinction with the server * side, where md_object and dt_object are used, is that cl_object "fans out" * at the lov/sns level: depending on the file layout, single file is * represented as a set of "sub-objects" (stripes). At the implementation * level, struct lov_object contains an array of cl_objects. Each sub-object * is a full-fledged cl_object, having its fid, living in the lru and hash * table. * * This leads to the next important difference with the server side: on the * client, it's quite usual to have objects with the different sequence of * layers. For example, typical top-object is composed of the following * layers: * * - vvp * - lov * * whereas its sub-objects are composed of * * - lovsub * - osc * * layers. Here "lovsub" is a mostly dummy layer, whose purpose is to keep * track of the object-subobject relationship. * * Sub-objects are not cached independently: when top-object is about to * be discarded from the memory, all its sub-objects are torn-down and * destroyed too. * * \see ccc_object, lov_object, lovsub_object, osc_object */ struct cl_object { /** super class */ struct lu_object co_lu; /** per-object-layer operations */ const struct cl_object_operations *co_ops; }; /** * Description of the client object configuration. This is used for the * creation of a new client object that is identified by a more state than * fid. */ struct cl_object_conf { /** Super-class. */ struct lu_object_conf coc_lu; union { /** * Object layout. This is consumed by lov. */ struct lustre_md *coc_md; /** * Description of particular stripe location in the * cluster. This is consumed by osc. */ struct lov_oinfo *coc_oinfo; } u; /** * VFS inode. This is consumed by vvp. */ struct inode *coc_inode; }; /** * Operations implemented for each cl object layer. * * \see vvp_ops, lov_ops, lovsub_ops, osc_ops */ struct cl_object_operations { /** * Initialize page slice for this layer. Called top-to-bottom through * every object layer when a new cl_page is instantiated. Layer * keeping private per-page data, or requiring its own page operations * vector should allocate these data here, and attach then to the page * by calling cl_page_slice_add(). \a vmpage is locked (in the VM * sense). Optional. * * \retval NULL success. * * \retval ERR_PTR(errno) failure code. * * \retval valid-pointer pointer to already existing referenced page * to be used instead of newly created. */ struct cl_page *(*coo_page_init)(const struct lu_env *env, struct cl_object *obj, struct cl_page *page, cfs_page_t *vmpage); /** * Initialize lock slice for this layer. Called top-to-bottom through * every object layer when a new cl_lock is instantiated. Layer * keeping private per-lock data, or requiring its own lock operations * vector should allocate these data here, and attach then to the lock * by calling cl_lock_slice_add(). Mandatory. */ int (*coo_lock_init)(const struct lu_env *env, struct cl_object *obj, struct cl_lock *lock, const struct cl_io *io); /** * Initialize io state for a given layer. * * called top-to-bottom once per io existence to initialize io * state. If layer wants to keep some state for this type of io, it * has to embed struct cl_io_slice in lu_env::le_ses, and register * slice with cl_io_slice_add(). It is guaranteed that all threads * participating in this io share the same session. */ int (*coo_io_init)(const struct lu_env *env, struct cl_object *obj, struct cl_io *io); /** * Fill portion of \a attr that this layer controls. This method is * called top-to-bottom through all object layers. * * \pre cl_object_header::coh_attr_guard of the top-object is locked. * * \return 0: to continue * \return +ve: to stop iterating through layers (but 0 is returned * from enclosing cl_object_attr_get()) * \return -ve: to signal error */ int (*coo_attr_get)(const struct lu_env *env, struct cl_object *obj, struct cl_attr *attr); /** * Update attributes. * * \a valid is a bitmask composed from enum #cl_attr_valid, and * indicating what attributes are to be set. * * \pre cl_object_header::coh_attr_guard of the top-object is locked. * * \return the same convention as for * cl_object_operations::coo_attr_get() is used. */ int (*coo_attr_set)(const struct lu_env *env, struct cl_object *obj, const struct cl_attr *attr, unsigned valid); /** * Update object configuration. Called top-to-bottom to modify object * configuration. * * XXX error conditions and handling. */ int (*coo_conf_set)(const struct lu_env *env, struct cl_object *obj, const struct cl_object_conf *conf); /** * Glimpse ast. Executed when glimpse ast arrives for a lock on this * object. Layers are supposed to fill parts of \a lvb that will be * shipped to the glimpse originator as a glimpse result. * * \see ccc_object_glimpse(), lovsub_object_glimpse(), * \see osc_object_glimpse() */ int (*coo_glimpse)(const struct lu_env *env, const struct cl_object *obj, struct ost_lvb *lvb); }; /** * Extended header for client object. */ struct cl_object_header { /** Standard lu_object_header. cl_object::co_lu::lo_header points * here. */ struct lu_object_header coh_lu; /** \name locks * \todo XXX move locks below to the separate cache-lines, they are * mostly useless otherwise. */ /** @{ */ /** Lock protecting page tree. */ cfs_spinlock_t coh_page_guard; /** Lock protecting lock list. */ cfs_spinlock_t coh_lock_guard; /** @} locks */ /** Radix tree of cl_page's, cached for this object. */ struct radix_tree_root coh_tree; /** # of pages in radix tree. */ unsigned long coh_pages; /** List of cl_lock's granted for this object. */ cfs_list_t coh_locks; /** * Parent object. It is assumed that an object has a well-defined * parent, but not a well-defined child (there may be multiple * sub-objects, for the same top-object). cl_object_header::coh_parent * field allows certain code to be written generically, without * limiting possible cl_object layouts unduly. */ struct cl_object_header *coh_parent; /** * Protects consistency between cl_attr of parent object and * attributes of sub-objects, that the former is calculated ("merged") * from. * * \todo XXX this can be read/write lock if needed. */ cfs_spinlock_t coh_attr_guard; /** * Number of objects above this one: 0 for a top-object, 1 for its * sub-object, etc. */ unsigned coh_nesting; }; /** * Helper macro: iterate over all layers of the object \a obj, assigning every * layer top-to-bottom to \a slice. */ #define cl_object_for_each(slice, obj) \ cfs_list_for_each_entry((slice), \ &(obj)->co_lu.lo_header->loh_layers, \ co_lu.lo_linkage) /** * Helper macro: iterate over all layers of the object \a obj, assigning every * layer bottom-to-top to \a slice. */ #define cl_object_for_each_reverse(slice, obj) \ cfs_list_for_each_entry_reverse((slice), \ &(obj)->co_lu.lo_header->loh_layers, \ co_lu.lo_linkage) /** @} cl_object */ #ifndef pgoff_t #define pgoff_t unsigned long #endif #define CL_PAGE_EOF ((pgoff_t)~0ull) /** \addtogroup cl_page cl_page * @{ */ /** \struct cl_page * Layered client page. * * cl_page: represents a portion of a file, cached in the memory. All pages * of the given file are of the same size, and are kept in the radix tree * hanging off the cl_object. cl_page doesn't fan out, but as sub-objects * of the top-level file object are first class cl_objects, they have their * own radix trees of pages and hence page is implemented as a sequence of * struct cl_pages's, linked into double-linked list through * cl_page::cp_parent and cl_page::cp_child pointers, each residing in the * corresponding radix tree at the corresponding logical offset. * * cl_page is associated with VM page of the hosting environment (struct * page in Linux kernel, for example), cfs_page_t. It is assumed, that this * association is implemented by one of cl_page layers (top layer in the * current design) that * * - intercepts per-VM-page call-backs made by the environment (e.g., * memory pressure), * * - translates state (page flag bits) and locking between lustre and * environment. * * The association between cl_page and cfs_page_t is immutable and * established when cl_page is created. * * cl_page can be "owned" by a particular cl_io (see below), guaranteeing * this io an exclusive access to this page w.r.t. other io attempts and * various events changing page state (such as transfer completion, or * eviction of the page from the memory). Note, that in general cl_io * cannot be identified with a particular thread, and page ownership is not * exactly equal to the current thread holding a lock on the page. Layer * implementing association between cl_page and cfs_page_t has to implement * ownership on top of available synchronization mechanisms. * * While lustre client maintains the notion of an page ownership by io, * hosting MM/VM usually has its own page concurrency control * mechanisms. For example, in Linux, page access is synchronized by the * per-page PG_locked bit-lock, and generic kernel code (generic_file_*()) * takes care to acquire and release such locks as necessary around the * calls to the file system methods (->readpage(), ->prepare_write(), * ->commit_write(), etc.). This leads to the situation when there are two * different ways to own a page in the client: * * - client code explicitly and voluntary owns the page (cl_page_own()); * * - VM locks a page and then calls the client, that has "to assume" * the ownership from the VM (cl_page_assume()). * * Dual methods to release ownership are cl_page_disown() and * cl_page_unassume(). * * cl_page is reference counted (cl_page::cp_ref). When reference counter * drops to 0, the page is returned to the cache, unless it is in * cl_page_state::CPS_FREEING state, in which case it is immediately * destroyed. * * The general logic guaranteeing the absence of "existential races" for * pages is the following: * * - there are fixed known ways for a thread to obtain a new reference * to a page: * * - by doing a lookup in the cl_object radix tree, protected by the * spin-lock; * * - by starting from VM-locked cfs_page_t and following some * hosting environment method (e.g., following ->private pointer in * the case of Linux kernel), see cl_vmpage_page(); * * - when the page enters cl_page_state::CPS_FREEING state, all these * ways are severed with the proper synchronization * (cl_page_delete()); * * - entry into cl_page_state::CPS_FREEING is serialized by the VM page * lock; * * - no new references to the page in cl_page_state::CPS_FREEING state * are allowed (checked in cl_page_get()). * * Together this guarantees that when last reference to a * cl_page_state::CPS_FREEING page is released, it is safe to destroy the * page, as neither references to it can be acquired at that point, nor * ones exist. * * cl_page is a state machine. States are enumerated in enum * cl_page_state. Possible state transitions are enumerated in * cl_page_state_set(). State transition process (i.e., actual changing of * cl_page::cp_state field) is protected by the lock on the underlying VM * page. * * Linux Kernel implementation. * * Binding between cl_page and cfs_page_t (which is a typedef for * struct page) is implemented in the vvp layer. cl_page is attached to the * ->private pointer of the struct page, together with the setting of * PG_private bit in page->flags, and acquiring additional reference on the * struct page (much like struct buffer_head, or any similar file system * private data structures). * * PG_locked lock is used to implement both ownership and transfer * synchronization, that is, page is VM-locked in CPS_{OWNED,PAGE{IN,OUT}} * states. No additional references are acquired for the duration of the * transfer. * * \warning *THIS IS NOT* the behavior expected by the Linux kernel, where * write-out is "protected" by the special PG_writeback bit. */ /** * States of cl_page. cl_page.c assumes particular order here. * * The page state machine is rather crude, as it doesn't recognize finer page * states like "dirty" or "up to date". This is because such states are not * always well defined for the whole stack (see, for example, the * implementation of the read-ahead, that hides page up-to-dateness to track * cache hits accurately). Such sub-states are maintained by the layers that * are interested in them. */ enum cl_page_state { /** * Page is in the cache, un-owned. Page leaves cached state in the * following cases: * * - [cl_page_state::CPS_OWNED] io comes across the page and * owns it; * * - [cl_page_state::CPS_PAGEOUT] page is dirty, the * req-formation engine decides that it wants to include this page * into an cl_req being constructed, and yanks it from the cache; * * - [cl_page_state::CPS_FREEING] VM callback is executed to * evict the page form the memory; * * \invariant cl_page::cp_owner == NULL && cl_page::cp_req == NULL */ CPS_CACHED, /** * Page is exclusively owned by some cl_io. Page may end up in this * state as a result of * * - io creating new page and immediately owning it; * * - [cl_page_state::CPS_CACHED] io finding existing cached page * and owning it; * * - [cl_page_state::CPS_OWNED] io finding existing owned page * and waiting for owner to release the page; * * Page leaves owned state in the following cases: * * - [cl_page_state::CPS_CACHED] io decides to leave the page in * the cache, doing nothing; * * - [cl_page_state::CPS_PAGEIN] io starts read transfer for * this page; * * - [cl_page_state::CPS_PAGEOUT] io starts immediate write * transfer for this page; * * - [cl_page_state::CPS_FREEING] io decides to destroy this * page (e.g., as part of truncate or extent lock cancellation). * * \invariant cl_page::cp_owner != NULL && cl_page::cp_req == NULL */ CPS_OWNED, /** * Page is being written out, as a part of a transfer. This state is * entered when req-formation logic decided that it wants this page to * be sent through the wire _now_. Specifically, it means that once * this state is achieved, transfer completion handler (with either * success or failure indication) is guaranteed to be executed against * this page independently of any locks and any scheduling decisions * made by the hosting environment (that effectively means that the * page is never put into cl_page_state::CPS_PAGEOUT state "in * advance". This property is mentioned, because it is important when * reasoning about possible dead-locks in the system). The page can * enter this state as a result of * * - [cl_page_state::CPS_OWNED] an io requesting an immediate * write-out of this page, or * * - [cl_page_state::CPS_CACHED] req-forming engine deciding * that it has enough dirty pages cached to issue a "good" * transfer. * * The page leaves cl_page_state::CPS_PAGEOUT state when the transfer * is completed---it is moved into cl_page_state::CPS_CACHED state. * * Underlying VM page is locked for the duration of transfer. * * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL */ CPS_PAGEOUT, /** * Page is being read in, as a part of a transfer. This is quite * similar to the cl_page_state::CPS_PAGEOUT state, except that * read-in is always "immediate"---there is no such thing a sudden * construction of read cl_req from cached, presumably not up to date, * pages. * * Underlying VM page is locked for the duration of transfer. * * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL */ CPS_PAGEIN, /** * Page is being destroyed. This state is entered when client decides * that page has to be deleted from its host object, as, e.g., a part * of truncate. * * Once this state is reached, there is no way to escape it. * * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req == NULL */ CPS_FREEING, CPS_NR }; enum cl_page_type { /** Host page, the page is from the host inode which the cl_page * belongs to. */ CPT_CACHEABLE = 1, /** Transient page, the transient cl_page is used to bind a cl_page * to vmpage which is not belonging to the same object of cl_page. * it is used in DirectIO, lockless IO and liblustre. */ CPT_TRANSIENT, }; /** * Flags maintained for every cl_page. */ enum cl_page_flags { /** * Set when pagein completes. Used for debugging (read completes at * most once for a page). */ CPF_READ_COMPLETED = 1 << 0 }; /** * Fields are protected by the lock on cfs_page_t, except for atomics and * immutables. * * \invariant Data type invariants are in cl_page_invariant(). Basically: * cl_page::cp_parent and cl_page::cp_child are a well-formed double-linked * list, consistent with the parent/child pointers in the cl_page::cp_obj and * cl_page::cp_owner (when set). */ struct cl_page { /** Reference counter. */ cfs_atomic_t cp_ref; /** An object this page is a part of. Immutable after creation. */ struct cl_object *cp_obj; /** Logical page index within the object. Immutable after creation. */ pgoff_t cp_index; /** List of slices. Immutable after creation. */ cfs_list_t cp_layers; /** Parent page, NULL for top-level page. Immutable after creation. */ struct cl_page *cp_parent; /** Lower-layer page. NULL for bottommost page. Immutable after * creation. */ struct cl_page *cp_child; /** * Page state. This field is const to avoid accidental update, it is * modified only internally within cl_page.c. Protected by a VM lock. */ const enum cl_page_state cp_state; /** * Linkage of pages within some group. Protected by * cl_page::cp_mutex. */ cfs_list_t cp_batch; /** Mutex serializing membership of a page in a batch. */ cfs_mutex_t cp_mutex; /** Linkage of pages within cl_req. */ cfs_list_t cp_flight; /** Transfer error. */ int cp_error; /** * Page type. Only CPT_TRANSIENT is used so far. Immutable after * creation. */ enum cl_page_type cp_type; /** * Owning IO in cl_page_state::CPS_OWNED state. Sub-page can be owned * by sub-io. Protected by a VM lock. */ struct cl_io *cp_owner; /** * Debug information, the task is owning the page. */ cfs_task_t *cp_task; /** * Owning IO request in cl_page_state::CPS_PAGEOUT and * cl_page_state::CPS_PAGEIN states. This field is maintained only in * the top-level pages. Protected by a VM lock. */ struct cl_req *cp_req; /** List of references to this page, for debugging. */ struct lu_ref cp_reference; /** Link to an object, for debugging. */ struct lu_ref_link *cp_obj_ref; /** Link to a queue, for debugging. */ struct lu_ref_link *cp_queue_ref; /** Per-page flags from enum cl_page_flags. Protected by a VM lock. */ unsigned cp_flags; /** Assigned if doing a sync_io */ struct cl_sync_io *cp_sync_io; }; /** * Per-layer part of cl_page. * * \see ccc_page, lov_page, osc_page */ struct cl_page_slice { struct cl_page *cpl_page; /** * Object slice corresponding to this page slice. Immutable after * creation. */ struct cl_object *cpl_obj; const struct cl_page_operations *cpl_ops; /** Linkage into cl_page::cp_layers. Immutable after creation. */ cfs_list_t cpl_linkage; }; /** * Lock mode. For the client extent locks. * * \warning: cl_lock_mode_match() assumes particular ordering here. * \ingroup cl_lock */ enum cl_lock_mode { /** * Mode of a lock that protects no data, and exists only as a * placeholder. This is used for `glimpse' requests. A phantom lock * might get promoted to real lock at some point. */ CLM_PHANTOM, CLM_READ, CLM_WRITE, CLM_GROUP }; /** * Requested transfer type. * \ingroup cl_req */ enum cl_req_type { CRT_READ, CRT_WRITE, CRT_NR }; /** * Per-layer page operations. * * Methods taking an \a io argument are for the activity happening in the * context of given \a io. Page is assumed to be owned by that io, except for * the obvious cases (like cl_page_operations::cpo_own()). * * \see vvp_page_ops, lov_page_ops, osc_page_ops */ struct cl_page_operations { /** * cl_page<->cfs_page_t methods. Only one layer in the stack has to * implement these. Current code assumes that this functionality is * provided by the topmost layer, see cl_page_disown0() as an example. */ /** * \return the underlying VM page. Optional. */ cfs_page_t *(*cpo_vmpage)(const struct lu_env *env, const struct cl_page_slice *slice); /** * Called when \a io acquires this page into the exclusive * ownership. When this method returns, it is guaranteed that the is * not owned by other io, and no transfer is going on against * it. Optional. * * \see cl_page_own() * \see vvp_page_own(), lov_page_own() */ int (*cpo_own)(const struct lu_env *env, const struct cl_page_slice *slice, struct cl_io *io, int nonblock); /** Called when ownership it yielded. Optional. * * \see cl_page_disown() * \see vvp_page_disown() */ void (*cpo_disown)(const struct lu_env *env, const struct cl_page_slice *slice, struct cl_io *io); /** * Called for a page that is already "owned" by \a io from VM point of * view. Optional. * * \see cl_page_assume() * \see vvp_page_assume(), lov_page_assume() */ void (*cpo_assume)(const struct lu_env *env, const struct cl_page_slice *slice, struct cl_io *io); /** Dual to cl_page_operations::cpo_assume(). Optional. Called * bottom-to-top when IO releases a page without actually unlocking * it. * * \see cl_page_unassume() * \see vvp_page_unassume() */ void (*cpo_unassume)(const struct lu_env *env, const struct cl_page_slice *slice, struct cl_io *io); /** * Announces whether the page contains valid data or not by \a uptodate. * * \see cl_page_export() * \see vvp_page_export() */ void (*cpo_export)(const struct lu_env *env, const struct cl_page_slice *slice, int uptodate); /** * Unmaps page from the user space (if it is mapped). * * \see cl_page_unmap() * \see vvp_page_unmap() */ int (*cpo_unmap)(const struct lu_env *env, const struct cl_page_slice *slice, struct cl_io *io); /** * Checks whether underlying VM page is locked (in the suitable * sense). Used for assertions. * * \retval -EBUSY: page is protected by a lock of a given mode; * \retval -ENODATA: page is not protected by a lock; * \retval 0: this layer cannot decide. (Should never happen.) */ int (*cpo_is_vmlocked)(const struct lu_env *env, const struct cl_page_slice *slice); /** * Page destruction. */ /** * Called when page is truncated from the object. Optional. * * \see cl_page_discard() * \see vvp_page_discard(), osc_page_discard() */ void (*cpo_discard)(const struct lu_env *env, const struct cl_page_slice *slice, struct cl_io *io); /** * Called when page is removed from the cache, and is about to being * destroyed. Optional. * * \see cl_page_delete() * \see vvp_page_delete(), osc_page_delete() */ void (*cpo_delete)(const struct lu_env *env, const struct cl_page_slice *slice); /** Destructor. Frees resources and slice itself. */ void (*cpo_fini)(const struct lu_env *env, struct cl_page_slice *slice); /** * Checks whether the page is protected by a cl_lock. This is a * per-layer method, because certain layers have ways to check for the * lock much more efficiently than through the generic locks scan, or * implement locking mechanisms separate from cl_lock, e.g., * LL_FILE_GROUP_LOCKED in vvp. If \a pending is true, check for locks * being canceled, or scheduled for cancellation as soon as the last * user goes away, too. * * \retval -EBUSY: page is protected by a lock of a given mode; * \retval -ENODATA: page is not protected by a lock; * \retval 0: this layer cannot decide. * * \see cl_page_is_under_lock() */ int (*cpo_is_under_lock)(const struct lu_env *env, const struct cl_page_slice *slice, struct cl_io *io); /** * Optional debugging helper. Prints given page slice. * * \see cl_page_print() */ int (*cpo_print)(const struct lu_env *env, const struct cl_page_slice *slice, void *cookie, lu_printer_t p); /** * \name transfer * * Transfer methods. See comment on cl_req for a description of * transfer formation and life-cycle. * * @{ */ /** * Request type dependent vector of operations. * * Transfer operations depend on transfer mode (cl_req_type). To avoid * passing transfer mode to each and every of these methods, and to * avoid branching on request type inside of the methods, separate * methods for cl_req_type:CRT_READ and cl_req_type:CRT_WRITE are * provided. That is, method invocation usually looks like * * slice->cp_ops.io[req->crq_type].cpo_method(env, slice, ...); */ struct { /** * Called when a page is submitted for a transfer as a part of * cl_page_list. * * \return 0 : page is eligible for submission; * \return -EALREADY : skip this page; * \return -ve : error. * * \see cl_page_prep() */ int (*cpo_prep)(const struct lu_env *env, const struct cl_page_slice *slice, struct cl_io *io); /** * Completion handler. This is guaranteed to be eventually * fired after cl_page_operations::cpo_prep() or * cl_page_operations::cpo_make_ready() call. * * This method can be called in a non-blocking context. It is * guaranteed however, that the page involved and its object * are pinned in memory (and, hence, calling cl_page_put() is * safe). * * \see cl_page_completion() */ void (*cpo_completion)(const struct lu_env *env, const struct cl_page_slice *slice, int ioret); /** * Called when cached page is about to be added to the * cl_req as a part of req formation. * * \return 0 : proceed with this page; * \return -EAGAIN : skip this page; * \return -ve : error. * * \see cl_page_make_ready() */ int (*cpo_make_ready)(const struct lu_env *env, const struct cl_page_slice *slice); /** * Announce that this page is to be written out * opportunistically, that is, page is dirty, it is not * necessary to start write-out transfer right now, but * eventually page has to be written out. * * Main caller of this is the write path (see * vvp_io_commit_write()), using this method to build a * "transfer cache" from which large transfers are then * constructed by the req-formation engine. * * \todo XXX it would make sense to add page-age tracking * semantics here, and to oblige the req-formation engine to * send the page out not later than it is too old. * * \see cl_page_cache_add() */ int (*cpo_cache_add)(const struct lu_env *env, const struct cl_page_slice *slice, struct cl_io *io); } io[CRT_NR]; /** * Tell transfer engine that only [to, from] part of a page should be * transmitted. * * This is used for immediate transfers. * * \todo XXX this is not very good interface. It would be much better * if all transfer parameters were supplied as arguments to * cl_io_operations::cio_submit() call, but it is not clear how to do * this for page queues. * * \see cl_page_clip() */ void (*cpo_clip)(const struct lu_env *env, const struct cl_page_slice *slice, int from, int to); /** * \pre the page was queued for transferring. * \post page is removed from client's pending list, or -EBUSY * is returned if it has already been in transferring. * * This is one of seldom page operation which is: * 0. called from top level; * 1. don't have vmpage locked; * 2. every layer should synchronize execution of its ->cpo_cancel() * with completion handlers. Osc uses client obd lock for this * purpose. Based on there is no vvp_page_cancel and * lov_page_cancel(), cpo_cancel is defacto protected by client lock. * * \see osc_page_cancel(). */ int (*cpo_cancel)(const struct lu_env *env, const struct cl_page_slice *slice); /** @} transfer */ }; /** * Helper macro, dumping detailed information about \a page into a log. */ #define CL_PAGE_DEBUG(mask, env, page, format, ...) \ do { \ static DECLARE_LU_CDEBUG_PRINT_INFO(__info, mask); \ \ if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \ cl_page_print(env, &__info, lu_cdebug_printer, page); \ CDEBUG(mask, format , ## __VA_ARGS__); \ } \ } while (0) /** * Helper macro, dumping shorter information about \a page into a log. */ #define CL_PAGE_HEADER(mask, env, page, format, ...) \ do { \ static DECLARE_LU_CDEBUG_PRINT_INFO(__info, mask); \ \ if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \ cl_page_header_print(env, &__info, lu_cdebug_printer, page); \ CDEBUG(mask, format , ## __VA_ARGS__); \ } \ } while (0) /** @} cl_page */ /** \addtogroup cl_lock cl_lock * @{ */ /** \struct cl_lock * * Extent locking on the client. * * LAYERING * * The locking model of the new client code is built around * * struct cl_lock * * data-type representing an extent lock on a regular file. cl_lock is a * layered object (much like cl_object and cl_page), it consists of a header * (struct cl_lock) and a list of layers (struct cl_lock_slice), linked to * cl_lock::cll_layers list through cl_lock_slice::cls_linkage. * * All locks for a given object are linked into cl_object_header::coh_locks * list (protected by cl_object_header::coh_lock_guard spin-lock) through * cl_lock::cll_linkage. Currently this list is not sorted in any way. We can * sort it in starting lock offset, or use altogether different data structure * like a tree. * * Typical cl_lock consists of the two layers: * * - vvp_lock (vvp specific data), and * - lov_lock (lov specific data). * * lov_lock contains an array of sub-locks. Each of these sub-locks is a * normal cl_lock: it has a header (struct cl_lock) and a list of layers: * * - lovsub_lock, and * - osc_lock * * Each sub-lock is associated with a cl_object (representing stripe * sub-object or the file to which top-level cl_lock is associated to), and is * linked into that cl_object::coh_locks. In this respect cl_lock is similar to * cl_object (that at lov layer also fans out into multiple sub-objects), and * is different from cl_page, that doesn't fan out (there is usually exactly * one osc_page for every vvp_page). We shall call vvp-lov portion of the lock * a "top-lock" and its lovsub-osc portion a "sub-lock". * * LIFE CYCLE * * cl_lock is reference counted. When reference counter drops to 0, lock is * placed in the cache, except when lock is in CLS_FREEING state. CLS_FREEING * lock is destroyed when last reference is released. Referencing between * top-lock and its sub-locks is described in the lov documentation module. * * STATE MACHINE * * Also, cl_lock is a state machine. This requires some clarification. One of * the goals of client IO re-write was to make IO path non-blocking, or at * least to make it easier to make it non-blocking in the future. Here * `non-blocking' means that when a system call (read, write, truncate) * reaches a situation where it has to wait for a communication with the * server, it should --instead of waiting-- remember its current state and * switch to some other work. E.g,. instead of waiting for a lock enqueue, * client should proceed doing IO on the next stripe, etc. Obviously this is * rather radical redesign, and it is not planned to be fully implemented at * this time, instead we are putting some infrastructure in place, that would * make it easier to do asynchronous non-blocking IO easier in the * future. Specifically, where old locking code goes to sleep (waiting for * enqueue, for example), new code returns cl_lock_transition::CLO_WAIT. When * enqueue reply comes, its completion handler signals that lock state-machine * is ready to transit to the next state. There is some generic code in * cl_lock.c that sleeps, waiting for these signals. As a result, for users of * this cl_lock.c code, it looks like locking is done in normal blocking * fashion, and it the same time it is possible to switch to the non-blocking * locking (simply by returning cl_lock_transition::CLO_WAIT from cl_lock.c * functions). * * For a description of state machine states and transitions see enum * cl_lock_state. * * There are two ways to restrict a set of states which lock might move to: * * - placing a "hold" on a lock guarantees that lock will not be moved * into cl_lock_state::CLS_FREEING state until hold is released. Hold * can be only acquired on a lock that is not in * cl_lock_state::CLS_FREEING. All holds on a lock are counted in * cl_lock::cll_holds. Hold protects lock from cancellation and * destruction. Requests to cancel and destroy a lock on hold will be * recorded, but only honored when last hold on a lock is released; * * - placing a "user" on a lock guarantees that lock will not leave * cl_lock_state::CLS_NEW, cl_lock_state::CLS_QUEUING, * cl_lock_state::CLS_ENQUEUED and cl_lock_state::CLS_HELD set of * states, once it enters this set. That is, if a user is added onto a * lock in a state not from this set, it doesn't immediately enforce * lock to move to this set, but once lock enters this set it will * remain there until all users are removed. Lock users are counted in * cl_lock::cll_users. * * User is used to assure that lock is not canceled or destroyed while * it is being enqueued, or actively used by some IO. * * Currently, a user always comes with a hold (cl_lock_invariant() * checks that a number of holds is not less than a number of users). * * CONCURRENCY * * This is how lock state-machine operates. struct cl_lock contains a mutex * cl_lock::cll_guard that protects struct fields. * * - mutex is taken, and cl_lock::cll_state is examined. * * - for every state there are possible target states where lock can move * into. They are tried in order. Attempts to move into next state are * done by _try() functions in cl_lock.c:cl_{enqueue,unlock,wait}_try(). * * - if the transition can be performed immediately, state is changed, * and mutex is released. * * - if the transition requires blocking, _try() function returns * cl_lock_transition::CLO_WAIT. Caller unlocks mutex and goes to * sleep, waiting for possibility of lock state change. It is woken * up when some event occurs, that makes lock state change possible * (e.g., the reception of the reply from the server), and repeats * the loop. * * Top-lock and sub-lock has separate mutexes and the latter has to be taken * first to avoid dead-lock. * * To see an example of interaction of all these issues, take a look at the * lov_cl.c:lov_lock_enqueue() function. It is called as a part of * cl_enqueue_try(), and tries to advance top-lock to ENQUEUED state, by * advancing state-machines of its sub-locks (lov_lock_enqueue_one()). Note * also, that it uses trylock to grab sub-lock mutex to avoid dead-lock. It * also has to handle CEF_ASYNC enqueue, when sub-locks enqueues have to be * done in parallel, rather than one after another (this is used for glimpse * locks, that cannot dead-lock). * * INTERFACE AND USAGE * * struct cl_lock_operations provide a number of call-backs that are invoked * when events of interest occurs. Layers can intercept and handle glimpse, * blocking, cancel ASTs and a reception of the reply from the server. * * One important difference with the old client locking model is that new * client has a representation for the top-lock, whereas in the old code only * sub-locks existed as real data structures and file-level locks are * represented by "request sets" that are created and destroyed on each and * every lock creation. * * Top-locks are cached, and can be found in the cache by the system calls. It * is possible that top-lock is in cache, but some of its sub-locks were * canceled and destroyed. In that case top-lock has to be enqueued again * before it can be used. * * Overall process of the locking during IO operation is as following: * * - once parameters for IO are setup in cl_io, cl_io_operations::cio_lock() * is called on each layer. Responsibility of this method is to add locks, * needed by a given layer into cl_io.ci_lockset. * * - once locks for all layers were collected, they are sorted to avoid * dead-locks (cl_io_locks_sort()), and enqueued. * * - when all locks are acquired, IO is performed; * * - locks are released into cache. * * Striping introduces major additional complexity into locking. The * fundamental problem is that it is generally unsafe to actively use (hold) * two locks on the different OST servers at the same time, as this introduces * inter-server dependency and can lead to cascading evictions. * * Basic solution is to sub-divide large read/write IOs into smaller pieces so * that no multi-stripe locks are taken (note that this design abandons POSIX * read/write semantics). Such pieces ideally can be executed concurrently. At * the same time, certain types of IO cannot be sub-divived, without * sacrificing correctness. This includes: * * - O_APPEND write, where [0, EOF] lock has to be taken, to guarantee * atomicity; * * - ftruncate(fd, offset), where [offset, EOF] lock has to be taken. * * Also, in the case of read(fd, buf, count) or write(fd, buf, count), where * buf is a part of memory mapped Lustre file, a lock or locks protecting buf * has to be held together with the usual lock on [offset, offset + count]. * * As multi-stripe locks have to be allowed, it makes sense to cache them, so * that, for example, a sequence of O_APPEND writes can proceed quickly * without going down to the individual stripes to do lock matching. On the * other hand, multi-stripe locks shouldn't be used by normal read/write * calls. To achieve this, every layer can implement ->clo_fits_into() method, * that is called by lock matching code (cl_lock_lookup()), and that can be * used to selectively disable matching of certain locks for certain IOs. For * exmaple, lov layer implements lov_lock_fits_into() that allow multi-stripe * locks to be matched only for truncates and O_APPEND writes. * * Interaction with DLM * * In the expected setup, cl_lock is ultimately backed up by a collection of * DLM locks (struct ldlm_lock). Association between cl_lock and DLM lock is * implemented in osc layer, that also matches DLM events (ASTs, cancellation, * etc.) into cl_lock_operation calls. See struct osc_lock for a more detailed * description of interaction with DLM. */ /** * Lock description. */ struct cl_lock_descr { /** Object this lock is granted for. */ struct cl_object *cld_obj; /** Index of the first page protected by this lock. */ pgoff_t cld_start; /** Index of the last page (inclusive) protected by this lock. */ pgoff_t cld_end; /** Group ID, for group lock */ __u64 cld_gid; /** Lock mode. */ enum cl_lock_mode cld_mode; /** * flags to enqueue lock. A combination of bit-flags from * enum cl_enq_flags. */ __u32 cld_enq_flags; }; #define DDESCR "%s(%d):[%lu, %lu]" #define PDESCR(descr) \ cl_lock_mode_name((descr)->cld_mode), (descr)->cld_mode, \ (descr)->cld_start, (descr)->cld_end const char *cl_lock_mode_name(const enum cl_lock_mode mode); /** * Lock state-machine states. * * \htmlonly *
 *
 * Possible state transitions:
 *
 *              +------------------>NEW
 *              |                    |
 *              |                    | cl_enqueue_try()
 *              |                    |
 *              |    cl_unuse_try()  V
 *              |  +--------------QUEUING (*)
 *              |  |                 |
 *              |  |                 | cl_enqueue_try()
 *              |  |                 |
 *              |  | cl_unuse_try()  V
 *    sub-lock  |  +-------------ENQUEUED (*)
 *    canceled  |  |                 |
 *              |  |                 | cl_wait_try()
 *              |  |                 |
 *              |  |                (R)
 *              |  |                 |
 *              |  |                 V
 *              |  |                HELD<---------+
 *              |  |                 |            |
 *              |  |                 |            | cl_use_try()
 *              |  |  cl_unuse_try() |            |
 *              |  |                 |            |
 *              |  |                 V         ---+ 
 *              |  +------------>INTRANSIT (D) <--+
 *              |                    |            |
 *              |     cl_unuse_try() |            | cached lock found
 *              |                    |            | cl_use_try()
 *              |                    |            |
 *              |                    V            |
 *              +------------------CACHED---------+
 *                                   |
 *                                  (C)
 *                                   |
 *                                   V
 *                                FREEING
 *
 * Legend:
 *
 *         In states marked with (*) transition to the same state (i.e., a loop
 *         in the diagram) is possible.
 *
 *         (R) is the point where Receive call-back is invoked: it allows layers
 *         to handle arrival of lock reply.
 *
 *         (C) is the point where Cancellation call-back is invoked.
 *
 *         (D) is the transit state which means the lock is changing.
 *
 *         Transition to FREEING state is possible from any other state in the
 *         diagram in case of unrecoverable error.
 * 
* \endhtmlonly * * These states are for individual cl_lock object. Top-lock and its sub-locks * can be in the different states. Another way to say this is that we have * nested state-machines. * * Separate QUEUING and ENQUEUED states are needed to support non-blocking * operation for locks with multiple sub-locks. Imagine lock on a file F, that * intersects 3 stripes S0, S1, and S2. To enqueue F client has to send * enqueue to S0, wait for its completion, then send enqueue for S1, wait for * its completion and at last enqueue lock for S2, and wait for its * completion. In that case, top-lock is in QUEUING state while S0, S1 are * handled, and is in ENQUEUED state after enqueue to S2 has been sent (note * that in this case, sub-locks move from state to state, and top-lock remains * in the same state). */ enum cl_lock_state { /** * Lock that wasn't yet enqueued */ CLS_NEW, /** * Enqueue is in progress, blocking for some intermediate interaction * with the other side. */ CLS_QUEUING, /** * Lock is fully enqueued, waiting for server to reply when it is * granted. */ CLS_ENQUEUED, /** * Lock granted, actively used by some IO. */ CLS_HELD, /** * This state is used to mark the lock is being used, or unused. * We need this state because the lock may have several sublocks, * so it's impossible to have an atomic way to bring all sublocks * into CLS_HELD state at use case, or all sublocks to CLS_CACHED * at unuse case. * If a thread is referring to a lock, and it sees the lock is in this * state, it must wait for the lock. * See state diagram for details. */ CLS_INTRANSIT, /** * Lock granted, not used. */ CLS_CACHED, /** * Lock is being destroyed. */ CLS_FREEING, CLS_NR }; enum cl_lock_flags { /** * lock has been cancelled. This flag is never cleared once set (by * cl_lock_cancel0()). */ CLF_CANCELLED = 1 << 0, /** cancellation is pending for this lock. */ CLF_CANCELPEND = 1 << 1, /** destruction is pending for this lock. */ CLF_DOOMED = 1 << 2 }; /** * Lock closure. * * Lock closure is a collection of locks (both top-locks and sub-locks) that * might be updated in a result of an operation on a certain lock (which lock * this is a closure of). * * Closures are needed to guarantee dead-lock freedom in the presence of * * - nested state-machines (top-lock state-machine composed of sub-lock * state-machines), and * * - shared sub-locks. * * Specifically, many operations, such as lock enqueue, wait, unlock, * etc. start from a top-lock, and then operate on a sub-locks of this * top-lock, holding a top-lock mutex. When sub-lock state changes as a result * of such operation, this change has to be propagated to all top-locks that * share this sub-lock. Obviously, no natural lock ordering (e.g., * top-to-bottom or bottom-to-top) captures this scenario, so try-locking has * to be used. Lock closure systematizes this try-and-repeat logic. */ struct cl_lock_closure { /** * Lock that is mutexed when closure construction is started. When * closure in is `wait' mode (cl_lock_closure::clc_wait), mutex on * origin is released before waiting. */ struct cl_lock *clc_origin; /** * List of enclosed locks, so far. Locks are linked here through * cl_lock::cll_inclosure. */ cfs_list_t clc_list; /** * True iff closure is in a `wait' mode. This determines what * cl_lock_enclosure() does when a lock L to be added to the closure * is currently mutexed by some other thread. * * If cl_lock_closure::clc_wait is not set, then closure construction * fails with CLO_REPEAT immediately. * * In wait mode, cl_lock_enclosure() waits until next attempt to build * a closure might succeed. To this end it releases an origin mutex * (cl_lock_closure::clc_origin), that has to be the only lock mutex * owned by the current thread, and then waits on L mutex (by grabbing * it and immediately releasing), before returning CLO_REPEAT to the * caller. */ int clc_wait; /** Number of locks in the closure. */ int clc_nr; }; /** * Layered client lock. */ struct cl_lock { /** Reference counter. */ cfs_atomic_t cll_ref; /** List of slices. Immutable after creation. */ cfs_list_t cll_layers; /** * Linkage into cl_lock::cll_descr::cld_obj::coh_locks list. Protected * by cl_lock::cll_descr::cld_obj::coh_lock_guard. */ cfs_list_t cll_linkage; /** * Parameters of this lock. Protected by * cl_lock::cll_descr::cld_obj::coh_lock_guard nested within * cl_lock::cll_guard. Modified only on lock creation and in * cl_lock_modify(). */ struct cl_lock_descr cll_descr; /** Protected by cl_lock::cll_guard. */ enum cl_lock_state cll_state; /** signals state changes. */ cfs_waitq_t cll_wq; /** * Recursive lock, most fields in cl_lock{} are protected by this. * * Locking rules: this mutex is never held across network * communication, except when lock is being canceled. * * Lock ordering: a mutex of a sub-lock is taken first, then a mutex * on a top-lock. Other direction is implemented through a * try-lock-repeat loop. Mutices of unrelated locks can be taken only * by try-locking. * * \see osc_lock_enqueue_wait(), lov_lock_cancel(), lov_sublock_wait(). */ cfs_mutex_t cll_guard; cfs_task_t *cll_guarder; int cll_depth; /** * the owner for INTRANSIT state */ cfs_task_t *cll_intransit_owner; int cll_error; /** * Number of holds on a lock. A hold prevents a lock from being * canceled and destroyed. Protected by cl_lock::cll_guard. * * \see cl_lock_hold(), cl_lock_unhold(), cl_lock_release() */ int cll_holds; /** * Number of lock users. Valid in cl_lock_state::CLS_HELD state * only. Lock user pins lock in CLS_HELD state. Protected by * cl_lock::cll_guard. * * \see cl_wait(), cl_unuse(). */ int cll_users; /** * Flag bit-mask. Values from enum cl_lock_flags. Updates are * protected by cl_lock::cll_guard. */ unsigned long cll_flags; /** * A linkage into a list of locks in a closure. * * \see cl_lock_closure */ cfs_list_t cll_inclosure; /** * Confict lock at queuing time. */ struct cl_lock *cll_conflict; /** * A list of references to this lock, for debugging. */ struct lu_ref cll_reference; /** * A list of holds on this lock, for debugging. */ struct lu_ref cll_holders; /** * A reference for cl_lock::cll_descr::cld_obj. For debugging. */ struct lu_ref_link *cll_obj_ref; #ifdef CONFIG_LOCKDEP /* "dep_map" name is assumed by lockdep.h macros. */ struct lockdep_map dep_map; #endif }; /** * Per-layer part of cl_lock * * \see ccc_lock, lov_lock, lovsub_lock, osc_lock */ struct cl_lock_slice { struct cl_lock *cls_lock; /** Object slice corresponding to this lock slice. Immutable after * creation. */ struct cl_object *cls_obj; const struct cl_lock_operations *cls_ops; /** Linkage into cl_lock::cll_layers. Immutable after creation. */ cfs_list_t cls_linkage; }; /** * Possible (non-error) return values of ->clo_{enqueue,wait,unlock}(). * * NOTE: lov_subresult() depends on ordering here. */ enum cl_lock_transition { /** operation cannot be completed immediately. Wait for state change. */ CLO_WAIT = 1, /** operation had to release lock mutex, restart. */ CLO_REPEAT = 2 }; /** * * \see vvp_lock_ops, lov_lock_ops, lovsub_lock_ops, osc_lock_ops */ struct cl_lock_operations { /** * \name statemachine * * State machine transitions. These 3 methods are called to transfer * lock from one state to another, as described in the commentary * above enum #cl_lock_state. * * \retval 0 this layer has nothing more to do to before * transition to the target state happens; * * \retval CLO_REPEAT method had to release and re-acquire cl_lock * mutex, repeat invocation of transition method * across all layers; * * \retval CLO_WAIT this layer cannot move to the target state * immediately, as it has to wait for certain event * (e.g., the communication with the server). It * is guaranteed, that when the state transfer * becomes possible, cl_lock::cll_wq wait-queue * is signaled. Caller can wait for this event by * calling cl_lock_state_wait(); * * \retval -ve failure, abort state transition, move the lock * into cl_lock_state::CLS_FREEING state, and set * cl_lock::cll_error. * * Once all layers voted to agree to transition (by returning 0), lock * is moved into corresponding target state. All state transition * methods are optional. */ /** @{ */ /** * Attempts to enqueue the lock. Called top-to-bottom. * * \see ccc_lock_enqueue(), lov_lock_enqueue(), lovsub_lock_enqueue(), * \see osc_lock_enqueue() */ int (*clo_enqueue)(const struct lu_env *env, const struct cl_lock_slice *slice, struct cl_io *io, __u32 enqflags); /** * Attempts to wait for enqueue result. Called top-to-bottom. * * \see ccc_lock_wait(), lov_lock_wait(), osc_lock_wait() */ int (*clo_wait)(const struct lu_env *env, const struct cl_lock_slice *slice); /** * Attempts to unlock the lock. Called bottom-to-top. In addition to * usual return values of lock state-machine methods, this can return * -ESTALE to indicate that lock cannot be returned to the cache, and * has to be re-initialized. * unuse is a one-shot operation, so it must NOT return CLO_WAIT. * * \see ccc_lock_unuse(), lov_lock_unuse(), osc_lock_unuse() */ int (*clo_unuse)(const struct lu_env *env, const struct cl_lock_slice *slice); /** * Notifies layer that cached lock is started being used. * * \pre lock->cll_state == CLS_CACHED * * \see lov_lock_use(), osc_lock_use() */ int (*clo_use)(const struct lu_env *env, const struct cl_lock_slice *slice); /** @} statemachine */ /** * A method invoked when lock state is changed (as a result of state * transition). This is used, for example, to track when the state of * a sub-lock changes, to propagate this change to the corresponding * top-lock. Optional * * \see lovsub_lock_state() */ void (*clo_state)(const struct lu_env *env, const struct cl_lock_slice *slice, enum cl_lock_state st); /** * Returns true, iff given lock is suitable for the given io, idea * being, that there are certain "unsafe" locks, e.g., ones acquired * for O_APPEND writes, that we don't want to re-use for a normal * write, to avoid the danger of cascading evictions. Optional. Runs * under cl_object_header::coh_lock_guard. * * XXX this should take more information about lock needed by * io. Probably lock description or something similar. * * \see lov_fits_into() */ int (*clo_fits_into)(const struct lu_env *env, const struct cl_lock_slice *slice, const struct cl_lock_descr *need, const struct cl_io *io); /** * \name ast * Asynchronous System Traps. All of then are optional, all are * executed bottom-to-top. */ /** @{ */ /** * Cancellation callback. Cancel a lock voluntarily, or under * the request of server. */ void (*clo_cancel)(const struct lu_env *env, const struct cl_lock_slice *slice); /** * Lock weighting ast. Executed to estimate how precious this lock * is. The sum of results across all layers is used to determine * whether lock worth keeping in cache given present memory usage. * * \see osc_lock_weigh(), vvp_lock_weigh(), lovsub_lock_weigh(). */ unsigned long (*clo_weigh)(const struct lu_env *env, const struct cl_lock_slice *slice); /** @} ast */ /** * \see lovsub_lock_closure() */ int (*clo_closure)(const struct lu_env *env, const struct cl_lock_slice *slice, struct cl_lock_closure *closure); /** * Executed bottom-to-top when lock description changes (e.g., as a * result of server granting more generous lock than was requested). * * \see lovsub_lock_modify() */ int (*clo_modify)(const struct lu_env *env, const struct cl_lock_slice *slice, const struct cl_lock_descr *updated); /** * Notifies layers (bottom-to-top) that lock is going to be * destroyed. Responsibility of layers is to prevent new references on * this lock from being acquired once this method returns. * * This can be called multiple times due to the races. * * \see cl_lock_delete() * \see osc_lock_delete(), lovsub_lock_delete() */ void (*clo_delete)(const struct lu_env *env, const struct cl_lock_slice *slice); /** * Destructor. Frees resources and the slice. * * \see ccc_lock_fini(), lov_lock_fini(), lovsub_lock_fini(), * \see osc_lock_fini() */ void (*clo_fini)(const struct lu_env *env, struct cl_lock_slice *slice); /** * Optional debugging helper. Prints given lock slice. */ int (*clo_print)(const struct lu_env *env, void *cookie, lu_printer_t p, const struct cl_lock_slice *slice); }; #define CL_LOCK_DEBUG(mask, env, lock, format, ...) \ do { \ static DECLARE_LU_CDEBUG_PRINT_INFO(__info, mask); \ \ if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \ cl_lock_print(env, &__info, lu_cdebug_printer, lock); \ CDEBUG(mask, format , ## __VA_ARGS__); \ } \ } while (0) /** @} cl_lock */ /** \addtogroup cl_page_list cl_page_list * Page list used to perform collective operations on a group of pages. * * Pages are added to the list one by one. cl_page_list acquires a reference * for every page in it. Page list is used to perform collective operations on * pages: * * - submit pages for an immediate transfer, * * - own pages on behalf of certain io (waiting for each page in turn), * * - discard pages. * * When list is finalized, it releases references on all pages it still has. * * \todo XXX concurrency control. * * @{ */ struct cl_page_list { unsigned pl_nr; cfs_list_t pl_pages; cfs_task_t *pl_owner; }; /** * A 2-queue of pages. A convenience data-type for common use case, 2-queue * contains an incoming page list and an outgoing page list. */ struct cl_2queue { struct cl_page_list c2_qin; struct cl_page_list c2_qout; }; /** @} cl_page_list */ /** \addtogroup cl_io cl_io * @{ */ /** \struct cl_io * I/O * * cl_io represents a high level I/O activity like * read(2)/write(2)/truncate(2) system call, or cancellation of an extent * lock. * * cl_io is a layered object, much like cl_{object,page,lock} but with one * important distinction. We want to minimize number of calls to the allocator * in the fast path, e.g., in the case of read(2) when everything is cached: * client already owns the lock over region being read, and data are cached * due to read-ahead. To avoid allocation of cl_io layers in such situations, * per-layer io state is stored in the session, associated with the io, see * struct {vvp,lov,osc}_io for example. Sessions allocation is amortized * by using free-lists, see cl_env_get(). * * There is a small predefined number of possible io types, enumerated in enum * cl_io_type. * * cl_io is a state machine, that can be advanced concurrently by the multiple * threads. It is up to these threads to control the concurrency and, * specifically, to detect when io is done, and its state can be safely * released. * * For read/write io overall execution plan is as following: * * (0) initialize io state through all layers; * * (1) loop: prepare chunk of work to do * * (2) call all layers to collect locks they need to process current chunk * * (3) sort all locks to avoid dead-locks, and acquire them * * (4) process the chunk: call per-page methods * (cl_io_operations::cio_read_page() for read, * cl_io_operations::cio_prepare_write(), * cl_io_operations::cio_commit_write() for write) * * (5) release locks * * (6) repeat loop. * * To implement the "parallel IO mode", lov layer creates sub-io's (lazily to * address allocation efficiency issues mentioned above), and returns with the * special error condition from per-page method when current sub-io has to * block. This causes io loop to be repeated, and lov switches to the next * sub-io in its cl_io_operations::cio_iter_init() implementation. */ /** IO types */ enum cl_io_type { /** read system call */ CIT_READ, /** write system call */ CIT_WRITE, /** truncate, utime system calls */ CIT_SETATTR, /** * page fault handling */ CIT_FAULT, /** * Miscellaneous io. This is used for occasional io activity that * doesn't fit into other types. Currently this is used for: * * - cancellation of an extent lock. This io exists as a context * to write dirty pages from under the lock being canceled back * to the server; * * - VM induced page write-out. An io context for writing page out * for memory cleansing; * * - glimpse. An io context to acquire glimpse lock. * * - grouplock. An io context to acquire group lock. * * CIT_MISC io is used simply as a context in which locks and pages * are manipulated. Such io has no internal "process", that is, * cl_io_loop() is never called for it. */ CIT_MISC, CIT_OP_NR }; /** * States of cl_io state machine */ enum cl_io_state { /** Not initialized. */ CIS_ZERO, /** Initialized. */ CIS_INIT, /** IO iteration started. */ CIS_IT_STARTED, /** Locks taken. */ CIS_LOCKED, /** Actual IO is in progress. */ CIS_IO_GOING, /** IO for the current iteration finished. */ CIS_IO_FINISHED, /** Locks released. */ CIS_UNLOCKED, /** Iteration completed. */ CIS_IT_ENDED, /** cl_io finalized. */ CIS_FINI }; enum cl_req_priority { CRP_NORMAL, CRP_CANCEL }; /** * IO state private for a layer. * * This is usually embedded into layer session data, rather than allocated * dynamically. * * \see vvp_io, lov_io, osc_io, ccc_io */ struct cl_io_slice { struct cl_io *cis_io; /** corresponding object slice. Immutable after creation. */ struct cl_object *cis_obj; /** io operations. Immutable after creation. */ const struct cl_io_operations *cis_iop; /** * linkage into a list of all slices for a given cl_io, hanging off * cl_io::ci_layers. Immutable after creation. */ cfs_list_t cis_linkage; }; /** * Per-layer io operations. * \see vvp_io_ops, lov_io_ops, lovsub_io_ops, osc_io_ops */ struct cl_io_operations { /** * Vector of io state transition methods for every io type. * * \see cl_page_operations::io */ struct { /** * Prepare io iteration at a given layer. * * Called top-to-bottom at the beginning of each iteration of * "io loop" (if it makes sense for this type of io). Here * layer selects what work it will do during this iteration. * * \see cl_io_operations::cio_iter_fini() */ int (*cio_iter_init) (const struct lu_env *env, const struct cl_io_slice *slice); /** * Finalize io iteration. * * Called bottom-to-top at the end of each iteration of "io * loop". Here layers can decide whether IO has to be * continued. * * \see cl_io_operations::cio_iter_init() */ void (*cio_iter_fini) (const struct lu_env *env, const struct cl_io_slice *slice); /** * Collect locks for the current iteration of io. * * Called top-to-bottom to collect all locks necessary for * this iteration. This methods shouldn't actually enqueue * anything, instead it should post a lock through * cl_io_lock_add(). Once all locks are collected, they are * sorted and enqueued in the proper order. */ int (*cio_lock) (const struct lu_env *env, const struct cl_io_slice *slice); /** * Finalize unlocking. * * Called bottom-to-top to finish layer specific unlocking * functionality, after generic code released all locks * acquired by cl_io_operations::cio_lock(). */ void (*cio_unlock)(const struct lu_env *env, const struct cl_io_slice *slice); /** * Start io iteration. * * Once all locks are acquired, called top-to-bottom to * commence actual IO. In the current implementation, * top-level vvp_io_{read,write}_start() does all the work * synchronously by calling generic_file_*(), so other layers * are called when everything is done. */ int (*cio_start)(const struct lu_env *env, const struct cl_io_slice *slice); /** * Called top-to-bottom at the end of io loop. Here layer * might wait for an unfinished asynchronous io. */ void (*cio_end) (const struct lu_env *env, const struct cl_io_slice *slice); /** * Called bottom-to-top to notify layers that read/write IO * iteration finished, with \a nob bytes transferred. */ void (*cio_advance)(const struct lu_env *env, const struct cl_io_slice *slice, size_t nob); /** * Called once per io, bottom-to-top to release io resources. */ void (*cio_fini) (const struct lu_env *env, const struct cl_io_slice *slice); } op[CIT_OP_NR]; struct { /** * Submit pages from \a queue->c2_qin for IO, and move * successfully submitted pages into \a queue->c2_qout. Return * non-zero if failed to submit even the single page. If * submission failed after some pages were moved into \a * queue->c2_qout, completion callback with non-zero ioret is * executed on them. */ int (*cio_submit)(const struct lu_env *env, const struct cl_io_slice *slice, enum cl_req_type crt, struct cl_2queue *queue, enum cl_req_priority priority); } req_op[CRT_NR]; /** * Read missing page. * * Called by a top-level cl_io_operations::op[CIT_READ]::cio_start() * method, when it hits not-up-to-date page in the range. Optional. * * \pre io->ci_type == CIT_READ */ int (*cio_read_page)(const struct lu_env *env, const struct cl_io_slice *slice, const struct cl_page_slice *page); /** * Prepare write of a \a page. Called bottom-to-top by a top-level * cl_io_operations::op[CIT_WRITE]::cio_start() to prepare page for * get data from user-level buffer. * * \pre io->ci_type == CIT_WRITE * * \see vvp_io_prepare_write(), lov_io_prepare_write(), * osc_io_prepare_write(). */ int (*cio_prepare_write)(const struct lu_env *env, const struct cl_io_slice *slice, const struct cl_page_slice *page, unsigned from, unsigned to); /** * * \pre io->ci_type == CIT_WRITE * * \see vvp_io_commit_write(), lov_io_commit_write(), * osc_io_commit_write(). */ int (*cio_commit_write)(const struct lu_env *env, const struct cl_io_slice *slice, const struct cl_page_slice *page, unsigned from, unsigned to); /** * Optional debugging helper. Print given io slice. */ int (*cio_print)(const struct lu_env *env, void *cookie, lu_printer_t p, const struct cl_io_slice *slice); }; /** * Flags to lock enqueue procedure. * \ingroup cl_lock */ enum cl_enq_flags { /** * instruct server to not block, if conflicting lock is found. Instead * -EWOULDBLOCK is returned immediately. */ CEF_NONBLOCK = 0x00000001, /** * take lock asynchronously (out of order), as it cannot * deadlock. This is for LDLM_FL_HAS_INTENT locks used for glimpsing. */ CEF_ASYNC = 0x00000002, /** * tell the server to instruct (though a flag in the blocking ast) an * owner of the conflicting lock, that it can drop dirty pages * protected by this lock, without sending them to the server. */ CEF_DISCARD_DATA = 0x00000004, /** * tell the sub layers that it must be a `real' lock. This is used for * mmapped-buffer locks and glimpse locks that must be never converted * into lockless mode. * * \see vvp_mmap_locks(), cl_glimpse_lock(). */ CEF_MUST = 0x00000008, /** * tell the sub layers that never request a `real' lock. This flag is * not used currently. * * cl_io::ci_lockreq and CEF_{MUST,NEVER} flags specify lockless * conversion policy: ci_lockreq describes generic information of lock * requirement for this IO, especially for locks which belong to the * object doing IO; however, lock itself may have precise requirements * that are described by the enqueue flags. */ CEF_NEVER = 0x00000010, /** * mask of enq_flags. */ CEF_MASK = 0x0000001f }; /** * Link between lock and io. Intermediate structure is needed, because the * same lock can be part of multiple io's simultaneously. */ struct cl_io_lock_link { /** linkage into one of cl_lockset lists. */ cfs_list_t cill_linkage; struct cl_lock_descr cill_descr; struct cl_lock *cill_lock; /** optional destructor */ void (*cill_fini)(const struct lu_env *env, struct cl_io_lock_link *link); }; /** * Lock-set represents a collection of locks, that io needs at a * time. Generally speaking, client tries to avoid holding multiple locks when * possible, because * * - holding extent locks over multiple ost's introduces the danger of * "cascading timeouts"; * * - holding multiple locks over the same ost is still dead-lock prone, * see comment in osc_lock_enqueue(), * * but there are certain situations where this is unavoidable: * * - O_APPEND writes have to take [0, EOF] lock for correctness; * * - truncate has to take [new-size, EOF] lock for correctness; * * - SNS has to take locks across full stripe for correctness; * * - in the case when user level buffer, supplied to {read,write}(file0), * is a part of a memory mapped lustre file, client has to take a dlm * locks on file0, and all files that back up the buffer (or a part of * the buffer, that is being processed in the current chunk, in any * case, there are situations where at least 2 locks are necessary). * * In such cases we at least try to take locks in the same consistent * order. To this end, all locks are first collected, then sorted, and then * enqueued. */ struct cl_lockset { /** locks to be acquired. */ cfs_list_t cls_todo; /** locks currently being processed. */ cfs_list_t cls_curr; /** locks acquired. */ cfs_list_t cls_done; }; /** * Lock requirements(demand) for IO. It should be cl_io_lock_req, * but 'req' is always to be thought as 'request' :-) */ enum cl_io_lock_dmd { /** Always lock data (e.g., O_APPEND). */ CILR_MANDATORY = 0, /** Layers are free to decide between local and global locking. */ CILR_MAYBE, /** Never lock: there is no cache (e.g., liblustre). */ CILR_NEVER }; struct cl_io_rw_common { loff_t crw_pos; size_t crw_count; int crw_nonblock; }; /** * State for io. * * cl_io is shared by all threads participating in this IO (in current * implementation only one thread advances IO, but parallel IO design and * concurrent copy_*_user() require multiple threads acting on the same IO. It * is up to these threads to serialize their activities, including updates to * mutable cl_io fields. */ struct cl_io { /** type of this IO. Immutable after creation. */ enum cl_io_type ci_type; /** current state of cl_io state machine. */ enum cl_io_state ci_state; /** main object this io is against. Immutable after creation. */ struct cl_object *ci_obj; /** * Upper layer io, of which this io is a part of. Immutable after * creation. */ struct cl_io *ci_parent; /** List of slices. Immutable after creation. */ cfs_list_t ci_layers; /** list of locks (to be) acquired by this io. */ struct cl_lockset ci_lockset; /** lock requirements, this is just a help info for sublayers. */ enum cl_io_lock_dmd ci_lockreq; /** * This io has held grouplock, to inform sublayers that * don't do lockless i/o. */ int ci_no_srvlock; union { struct cl_rd_io { struct cl_io_rw_common rd; } ci_rd; struct cl_wr_io { struct cl_io_rw_common wr; int wr_append; } ci_wr; struct cl_io_rw_common ci_rw; struct cl_setattr_io { struct ost_lvb sa_attr; unsigned int sa_valid; struct obd_capa *sa_capa; } ci_setattr; struct cl_fault_io { /** page index within file. */ pgoff_t ft_index; /** bytes valid byte on a faulted page. */ int ft_nob; /** writable page? */ int ft_writable; /** page of an executable? */ int ft_executable; /** resulting page */ struct cl_page *ft_page; } ci_fault; } u; struct cl_2queue ci_queue; size_t ci_nob; int ci_result; int ci_continue; /** * Number of pages owned by this IO. For invariant checking. */ unsigned ci_owned_nr; }; /** @} cl_io */ /** \addtogroup cl_req cl_req * @{ */ /** \struct cl_req * Transfer. * * There are two possible modes of transfer initiation on the client: * * - immediate transfer: this is started when a high level io wants a page * or a collection of pages to be transferred right away. Examples: * read-ahead, synchronous read in the case of non-page aligned write, * page write-out as a part of extent lock cancellation, page write-out * as a part of memory cleansing. Immediate transfer can be both * cl_req_type::CRT_READ and cl_req_type::CRT_WRITE; * * - opportunistic transfer (cl_req_type::CRT_WRITE only), that happens * when io wants to transfer a page to the server some time later, when * it can be done efficiently. Example: pages dirtied by the write(2) * path. * * In any case, transfer takes place in the form of a cl_req, which is a * representation for a network RPC. * * Pages queued for an opportunistic transfer are cached until it is decided * that efficient RPC can be composed of them. This decision is made by "a * req-formation engine", currently implemented as a part of osc * layer. Req-formation depends on many factors: the size of the resulting * RPC, whether or not multi-object RPCs are supported by the server, * max-rpc-in-flight limitations, size of the dirty cache, etc. * * For the immediate transfer io submits a cl_page_list, that req-formation * engine slices into cl_req's, possibly adding cached pages to some of * the resulting req's. * * Whenever a page from cl_page_list is added to a newly constructed req, its * cl_page_operations::cpo_prep() layer methods are called. At that moment, * page state is atomically changed from cl_page_state::CPS_OWNED to * cl_page_state::CPS_PAGEOUT or cl_page_state::CPS_PAGEIN, cl_page::cp_owner * is zeroed, and cl_page::cp_req is set to the * req. cl_page_operations::cpo_prep() method at the particular layer might * return -EALREADY to indicate that it does not need to submit this page * at all. This is possible, for example, if page, submitted for read, * became up-to-date in the meantime; and for write, the page don't have * dirty bit marked. \see cl_io_submit_rw() * * Whenever a cached page is added to a newly constructed req, its * cl_page_operations::cpo_make_ready() layer methods are called. At that * moment, page state is atomically changed from cl_page_state::CPS_CACHED to * cl_page_state::CPS_PAGEOUT, and cl_page::cp_req is set to * req. cl_page_operations::cpo_make_ready() method at the particular layer * might return -EAGAIN to indicate that this page is not eligible for the * transfer right now. * * FUTURE * * Plan is to divide transfers into "priority bands" (indicated when * submitting cl_page_list, and queuing a page for the opportunistic transfer) * and allow glueing of cached pages to immediate transfers only within single * band. This would make high priority transfers (like lock cancellation or * memory pressure induced write-out) really high priority. * */ /** * Per-transfer attributes. */ struct cl_req_attr { /** Generic attributes for the server consumption. */ struct obdo *cra_oa; /** Capability. */ struct obd_capa *cra_capa; }; /** * Transfer request operations definable at every layer. * * Concurrency: transfer formation engine synchronizes calls to all transfer * methods. */ struct cl_req_operations { /** * Invoked top-to-bottom by cl_req_prep() when transfer formation is * complete (all pages are added). * * \see osc_req_prep() */ int (*cro_prep)(const struct lu_env *env, const struct cl_req_slice *slice); /** * Called top-to-bottom to fill in \a oa fields. This is called twice * with different flags, see bug 10150 and osc_build_req(). * * \param obj an object from cl_req which attributes are to be set in * \a oa. * * \param oa struct obdo where attributes are placed * * \param flags \a oa fields to be filled. */ void (*cro_attr_set)(const struct lu_env *env, const struct cl_req_slice *slice, const struct cl_object *obj, struct cl_req_attr *attr, obd_valid flags); /** * Called top-to-bottom from cl_req_completion() to notify layers that * transfer completed. Has to free all state allocated by * cl_device_operations::cdo_req_init(). */ void (*cro_completion)(const struct lu_env *env, const struct cl_req_slice *slice, int ioret); }; /** * A per-object state that (potentially multi-object) transfer request keeps. */ struct cl_req_obj { /** object itself */ struct cl_object *ro_obj; /** reference to cl_req_obj::ro_obj. For debugging. */ struct lu_ref_link *ro_obj_ref; /* something else? Number of pages for a given object? */ }; /** * Transfer request. * * Transfer requests are not reference counted, because IO sub-system owns * them exclusively and knows when to free them. * * Life cycle. * * cl_req is created by cl_req_alloc() that calls * cl_device_operations::cdo_req_init() device methods to allocate per-req * state in every layer. * * Then pages are added (cl_req_page_add()), req keeps track of all objects it * contains pages for. * * Once all pages were collected, cl_page_operations::cpo_prep() method is * called top-to-bottom. At that point layers can modify req, let it pass, or * deny it completely. This is to support things like SNS that have transfer * ordering requirements invisible to the individual req-formation engine. * * On transfer completion (or transfer timeout, or failure to initiate the * transfer of an allocated req), cl_req_operations::cro_completion() method * is called, after execution of cl_page_operations::cpo_completion() of all * req's pages. */ struct cl_req { enum cl_req_type crq_type; /** A list of pages being transfered */ cfs_list_t crq_pages; /** Number of pages in cl_req::crq_pages */ unsigned crq_nrpages; /** An array of objects which pages are in ->crq_pages */ struct cl_req_obj *crq_o; /** Number of elements in cl_req::crq_objs[] */ unsigned crq_nrobjs; cfs_list_t crq_layers; }; /** * Per-layer state for request. */ struct cl_req_slice { struct cl_req *crs_req; struct cl_device *crs_dev; cfs_list_t crs_linkage; const struct cl_req_operations *crs_ops; }; /* @} cl_req */ /** * Stats for a generic cache (similar to inode, lu_object, etc. caches). */ struct cache_stats { const char *cs_name; /** how many entities were created at all */ cfs_atomic_t cs_created; /** how many cache lookups were performed */ cfs_atomic_t cs_lookup; /** how many times cache lookup resulted in a hit */ cfs_atomic_t cs_hit; /** how many entities are in the cache right now */ cfs_atomic_t cs_total; /** how many entities in the cache are actively used (and cannot be * evicted) right now */ cfs_atomic_t cs_busy; }; /** These are not exported so far */ void cache_stats_init (struct cache_stats *cs, const char *name); int cache_stats_print(const struct cache_stats *cs, char *page, int count, int header); /** * Client-side site. This represents particular client stack. "Global" * variables should (directly or indirectly) be added here to allow multiple * clients to co-exist in the single address space. */ struct cl_site { struct lu_site cs_lu; /** * Statistical counters. Atomics do not scale, something better like * per-cpu counters is needed. * * These are exported as /proc/fs/lustre/llite/.../site * * When interpreting keep in mind that both sub-locks (and sub-pages) * and top-locks (and top-pages) are accounted here. */ struct cache_stats cs_pages; struct cache_stats cs_locks; cfs_atomic_t cs_pages_state[CPS_NR]; cfs_atomic_t cs_locks_state[CLS_NR]; }; int cl_site_init (struct cl_site *s, struct cl_device *top); void cl_site_fini (struct cl_site *s); void cl_stack_fini(const struct lu_env *env, struct cl_device *cl); /** * Output client site statistical counters into a buffer. Suitable for * ll_rd_*()-style functions. */ int cl_site_stats_print(const struct cl_site *s, char *page, int count); /** * \name helpers * * Type conversion and accessory functions. */ /** @{ */ static inline struct cl_site *lu2cl_site(const struct lu_site *site) { return container_of(site, struct cl_site, cs_lu); } static inline int lu_device_is_cl(const struct lu_device *d) { return d->ld_type->ldt_tags & LU_DEVICE_CL; } static inline struct cl_device *lu2cl_dev(const struct lu_device *d) { LASSERT(d == NULL || IS_ERR(d) || lu_device_is_cl(d)); return container_of0(d, struct cl_device, cd_lu_dev); } static inline struct lu_device *cl2lu_dev(struct cl_device *d) { return &d->cd_lu_dev; } static inline struct cl_object *lu2cl(const struct lu_object *o) { LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->lo_dev)); return container_of0(o, struct cl_object, co_lu); } static inline const struct cl_object_conf * lu2cl_conf(const struct lu_object_conf *conf) { return container_of0(conf, struct cl_object_conf, coc_lu); } static inline struct cl_object *cl_object_next(const struct cl_object *obj) { return obj ? lu2cl(lu_object_next(&obj->co_lu)) : NULL; } static inline struct cl_device *cl_object_device(const struct cl_object *o) { LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->co_lu.lo_dev)); return container_of0(o->co_lu.lo_dev, struct cl_device, cd_lu_dev); } static inline struct cl_object_header *luh2coh(const struct lu_object_header *h) { return container_of0(h, struct cl_object_header, coh_lu); } static inline struct cl_site *cl_object_site(const struct cl_object *obj) { return lu2cl_site(obj->co_lu.lo_dev->ld_site); } static inline struct cl_object_header *cl_object_header(const struct cl_object *obj) { return luh2coh(obj->co_lu.lo_header); } static inline int cl_device_init(struct cl_device *d, struct lu_device_type *t) { return lu_device_init(&d->cd_lu_dev, t); } static inline void cl_device_fini(struct cl_device *d) { lu_device_fini(&d->cd_lu_dev); } void cl_page_slice_add(struct cl_page *page, struct cl_page_slice *slice, struct cl_object *obj, const struct cl_page_operations *ops); void cl_lock_slice_add(struct cl_lock *lock, struct cl_lock_slice *slice, struct cl_object *obj, const struct cl_lock_operations *ops); void cl_io_slice_add(struct cl_io *io, struct cl_io_slice *slice, struct cl_object *obj, const struct cl_io_operations *ops); void cl_req_slice_add(struct cl_req *req, struct cl_req_slice *slice, struct cl_device *dev, const struct cl_req_operations *ops); /** @} helpers */ /** \defgroup cl_object cl_object * @{ */ struct cl_object *cl_object_top (struct cl_object *o); struct cl_object *cl_object_find(const struct lu_env *env, struct cl_device *cd, const struct lu_fid *fid, const struct cl_object_conf *c); int cl_object_header_init(struct cl_object_header *h); void cl_object_header_fini(struct cl_object_header *h); void cl_object_put (const struct lu_env *env, struct cl_object *o); void cl_object_get (struct cl_object *o); void cl_object_attr_lock (struct cl_object *o); void cl_object_attr_unlock(struct cl_object *o); int cl_object_attr_get (const struct lu_env *env, struct cl_object *obj, struct cl_attr *attr); int cl_object_attr_set (const struct lu_env *env, struct cl_object *obj, const struct cl_attr *attr, unsigned valid); int cl_object_glimpse (const struct lu_env *env, struct cl_object *obj, struct ost_lvb *lvb); int cl_conf_set (const struct lu_env *env, struct cl_object *obj, const struct cl_object_conf *conf); void cl_object_prune (const struct lu_env *env, struct cl_object *obj); void cl_object_kill (const struct lu_env *env, struct cl_object *obj); int cl_object_has_locks (struct cl_object *obj); /** * Returns true, iff \a o0 and \a o1 are slices of the same object. */ static inline int cl_object_same(struct cl_object *o0, struct cl_object *o1) { return cl_object_header(o0) == cl_object_header(o1); } /** @} cl_object */ /** \defgroup cl_page cl_page * @{ */ struct cl_page *cl_page_lookup(struct cl_object_header *hdr, pgoff_t index); void cl_page_gang_lookup(const struct lu_env *env, struct cl_object *obj, struct cl_io *io, pgoff_t start, pgoff_t end, struct cl_page_list *plist, int nonblock, int *resched); struct cl_page *cl_page_find (const struct lu_env *env, struct cl_object *obj, pgoff_t idx, struct page *vmpage, enum cl_page_type type); struct cl_page *cl_page_find_sub (const struct lu_env *env, struct cl_object *obj, pgoff_t idx, struct page *vmpage, struct cl_page *parent); void cl_page_get (struct cl_page *page); void cl_page_put (const struct lu_env *env, struct cl_page *page); void cl_page_print (const struct lu_env *env, void *cookie, lu_printer_t printer, const struct cl_page *pg); void cl_page_header_print(const struct lu_env *env, void *cookie, lu_printer_t printer, const struct cl_page *pg); cfs_page_t *cl_page_vmpage (const struct lu_env *env, struct cl_page *page); struct cl_page *cl_vmpage_page (cfs_page_t *vmpage, struct cl_object *obj); struct cl_page *cl_page_top (struct cl_page *page); const struct cl_page_slice *cl_page_at(const struct cl_page *page, const struct lu_device_type *dtype); /** * \name ownership * * Functions dealing with the ownership of page by io. */ /** @{ */ int cl_page_own (const struct lu_env *env, struct cl_io *io, struct cl_page *page); int cl_page_own_try (const struct lu_env *env, struct cl_io *io, struct cl_page *page); void cl_page_assume (const struct lu_env *env, struct cl_io *io, struct cl_page *page); void cl_page_unassume (const struct lu_env *env, struct cl_io *io, struct cl_page *pg); void cl_page_disown (const struct lu_env *env, struct cl_io *io, struct cl_page *page); int cl_page_is_owned (const struct cl_page *pg, const struct cl_io *io); /** @} ownership */ /** * \name transfer * * Functions dealing with the preparation of a page for a transfer, and * tracking transfer state. */ /** @{ */ int cl_page_prep (const struct lu_env *env, struct cl_io *io, struct cl_page *pg, enum cl_req_type crt); void cl_page_completion (const struct lu_env *env, struct cl_page *pg, enum cl_req_type crt, int ioret); int cl_page_make_ready (const struct lu_env *env, struct cl_page *pg, enum cl_req_type crt); int cl_page_cache_add (const struct lu_env *env, struct cl_io *io, struct cl_page *pg, enum cl_req_type crt); void cl_page_clip (const struct lu_env *env, struct cl_page *pg, int from, int to); int cl_page_cancel (const struct lu_env *env, struct cl_page *page); /** @} transfer */ /** * \name helper routines * Functions to discard, delete and export a cl_page. */ /** @{ */ void cl_page_discard (const struct lu_env *env, struct cl_io *io, struct cl_page *pg); void cl_page_delete (const struct lu_env *env, struct cl_page *pg); int cl_page_unmap (const struct lu_env *env, struct cl_io *io, struct cl_page *pg); int cl_page_is_vmlocked (const struct lu_env *env, const struct cl_page *pg); void cl_page_export (const struct lu_env *env, struct cl_page *pg, int uptodate); int cl_page_is_under_lock(const struct lu_env *env, struct cl_io *io, struct cl_page *page); loff_t cl_offset (const struct cl_object *obj, pgoff_t idx); pgoff_t cl_index (const struct cl_object *obj, loff_t offset); int cl_page_size (const struct cl_object *obj); int cl_pages_prune (const struct lu_env *env, struct cl_object *obj); void cl_lock_print (const struct lu_env *env, void *cookie, lu_printer_t printer, const struct cl_lock *lock); void cl_lock_descr_print(const struct lu_env *env, void *cookie, lu_printer_t printer, const struct cl_lock_descr *descr); /* @} helper */ /** @} cl_page */ /** \defgroup cl_lock cl_lock * @{ */ struct cl_lock *cl_lock_hold(const struct lu_env *env, const struct cl_io *io, const struct cl_lock_descr *need, const char *scope, const void *source); struct cl_lock *cl_lock_peek(const struct lu_env *env, const struct cl_io *io, const struct cl_lock_descr *need, const char *scope, const void *source); struct cl_lock *cl_lock_request(const struct lu_env *env, struct cl_io *io, const struct cl_lock_descr *need, const char *scope, const void *source); struct cl_lock *cl_lock_at_page(const struct lu_env *env, struct cl_object *obj, struct cl_page *page, struct cl_lock *except, int pending, int canceld); const struct cl_lock_slice *cl_lock_at(const struct cl_lock *lock, const struct lu_device_type *dtype); void cl_lock_get (struct cl_lock *lock); void cl_lock_get_trust (struct cl_lock *lock); void cl_lock_put (const struct lu_env *env, struct cl_lock *lock); void cl_lock_hold_add (const struct lu_env *env, struct cl_lock *lock, const char *scope, const void *source); void cl_lock_unhold (const struct lu_env *env, struct cl_lock *lock, const char *scope, const void *source); void cl_lock_release (const struct lu_env *env, struct cl_lock *lock, const char *scope, const void *source); void cl_lock_user_add (const struct lu_env *env, struct cl_lock *lock); int cl_lock_user_del (const struct lu_env *env, struct cl_lock *lock); enum cl_lock_state cl_lock_intransit(const struct lu_env *env, struct cl_lock *lock); void cl_lock_extransit(const struct lu_env *env, struct cl_lock *lock, enum cl_lock_state state); int cl_lock_is_intransit(struct cl_lock *lock); int cl_lock_enqueue_wait(const struct lu_env *env, struct cl_lock *lock, int keep_mutex); /** \name statemachine statemachine * Interface to lock state machine consists of 3 parts: * * - "try" functions that attempt to effect a state transition. If state * transition is not possible right now (e.g., if it has to wait for some * asynchronous event to occur), these functions return * cl_lock_transition::CLO_WAIT. * * - "non-try" functions that implement synchronous blocking interface on * top of non-blocking "try" functions. These functions repeatedly call * corresponding "try" versions, and if state transition is not possible * immediately, wait for lock state change. * * - methods from cl_lock_operations, called by "try" functions. Lock can * be advanced to the target state only when all layers voted that they * are ready for this transition. "Try" functions call methods under lock * mutex. If a layer had to release a mutex, it re-acquires it and returns * cl_lock_transition::CLO_REPEAT, causing "try" function to call all * layers again. * * TRY NON-TRY METHOD FINAL STATE * * cl_enqueue_try() cl_enqueue() cl_lock_operations::clo_enqueue() CLS_ENQUEUED * * cl_wait_try() cl_wait() cl_lock_operations::clo_wait() CLS_HELD * * cl_unuse_try() cl_unuse() cl_lock_operations::clo_unuse() CLS_CACHED * * cl_use_try() NONE cl_lock_operations::clo_use() CLS_HELD * * @{ */ int cl_enqueue (const struct lu_env *env, struct cl_lock *lock, struct cl_io *io, __u32 flags); int cl_wait (const struct lu_env *env, struct cl_lock *lock); void cl_unuse (const struct lu_env *env, struct cl_lock *lock); int cl_enqueue_try(const struct lu_env *env, struct cl_lock *lock, struct cl_io *io, __u32 flags); int cl_unuse_try (const struct lu_env *env, struct cl_lock *lock); int cl_wait_try (const struct lu_env *env, struct cl_lock *lock); int cl_use_try (const struct lu_env *env, struct cl_lock *lock, int atomic); /** @} statemachine */ void cl_lock_signal (const struct lu_env *env, struct cl_lock *lock); int cl_lock_state_wait (const struct lu_env *env, struct cl_lock *lock); void cl_lock_state_set (const struct lu_env *env, struct cl_lock *lock, enum cl_lock_state state); int cl_queue_match (const cfs_list_t *queue, const struct cl_lock_descr *need); void cl_lock_mutex_get (const struct lu_env *env, struct cl_lock *lock); int cl_lock_mutex_try (const struct lu_env *env, struct cl_lock *lock); void cl_lock_mutex_put (const struct lu_env *env, struct cl_lock *lock); int cl_lock_is_mutexed (struct cl_lock *lock); int cl_lock_nr_mutexed (const struct lu_env *env); int cl_lock_page_out (const struct lu_env *env, struct cl_lock *lock, int discard); int cl_lock_ext_match (const struct cl_lock_descr *has, const struct cl_lock_descr *need); int cl_lock_descr_match(const struct cl_lock_descr *has, const struct cl_lock_descr *need); int cl_lock_mode_match (enum cl_lock_mode has, enum cl_lock_mode need); int cl_lock_modify (const struct lu_env *env, struct cl_lock *lock, const struct cl_lock_descr *desc); void cl_lock_closure_init (const struct lu_env *env, struct cl_lock_closure *closure, struct cl_lock *origin, int wait); void cl_lock_closure_fini (struct cl_lock_closure *closure); int cl_lock_closure_build(const struct lu_env *env, struct cl_lock *lock, struct cl_lock_closure *closure); void cl_lock_disclosure (const struct lu_env *env, struct cl_lock_closure *closure); int cl_lock_enclosure (const struct lu_env *env, struct cl_lock *lock, struct cl_lock_closure *closure); void cl_lock_cancel(const struct lu_env *env, struct cl_lock *lock); void cl_lock_delete(const struct lu_env *env, struct cl_lock *lock); void cl_lock_error (const struct lu_env *env, struct cl_lock *lock, int error); void cl_locks_prune(const struct lu_env *env, struct cl_object *obj, int wait); unsigned long cl_lock_weigh(const struct lu_env *env, struct cl_lock *lock); /** @} cl_lock */ /** \defgroup cl_io cl_io * @{ */ int cl_io_init (const struct lu_env *env, struct cl_io *io, enum cl_io_type iot, struct cl_object *obj); int cl_io_sub_init (const struct lu_env *env, struct cl_io *io, enum cl_io_type iot, struct cl_object *obj); int cl_io_rw_init (const struct lu_env *env, struct cl_io *io, enum cl_io_type iot, loff_t pos, size_t count); int cl_io_loop (const struct lu_env *env, struct cl_io *io); void cl_io_fini (const struct lu_env *env, struct cl_io *io); int cl_io_iter_init (const struct lu_env *env, struct cl_io *io); void cl_io_iter_fini (const struct lu_env *env, struct cl_io *io); int cl_io_lock (const struct lu_env *env, struct cl_io *io); void cl_io_unlock (const struct lu_env *env, struct cl_io *io); int cl_io_start (const struct lu_env *env, struct cl_io *io); void cl_io_end (const struct lu_env *env, struct cl_io *io); int cl_io_lock_add (const struct lu_env *env, struct cl_io *io, struct cl_io_lock_link *link); int cl_io_lock_alloc_add(const struct lu_env *env, struct cl_io *io, struct cl_lock_descr *descr); int cl_io_read_page (const struct lu_env *env, struct cl_io *io, struct cl_page *page); int cl_io_prepare_write(const struct lu_env *env, struct cl_io *io, struct cl_page *page, unsigned from, unsigned to); int cl_io_commit_write (const struct lu_env *env, struct cl_io *io, struct cl_page *page, unsigned from, unsigned to); int cl_io_submit_rw (const struct lu_env *env, struct cl_io *io, enum cl_req_type iot, struct cl_2queue *queue, enum cl_req_priority priority); int cl_io_submit_sync (const struct lu_env *env, struct cl_io *io, enum cl_req_type iot, struct cl_2queue *queue, enum cl_req_priority priority, long timeout); void cl_io_rw_advance (const struct lu_env *env, struct cl_io *io, size_t nob); int cl_io_cancel (const struct lu_env *env, struct cl_io *io, struct cl_page_list *queue); int cl_io_is_going (const struct lu_env *env); /** * True, iff \a io is an O_APPEND write(2). */ static inline int cl_io_is_append(const struct cl_io *io) { return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_append; } /** * True, iff \a io is a truncate(2). */ static inline int cl_io_is_trunc(const struct cl_io *io) { return io->ci_type == CIT_SETATTR && (io->u.ci_setattr.sa_valid & ATTR_SIZE); } struct cl_io *cl_io_top(struct cl_io *io); void cl_io_print(const struct lu_env *env, void *cookie, lu_printer_t printer, const struct cl_io *io); #define CL_IO_SLICE_CLEAN(foo_io, base) \ do { \ typeof(foo_io) __foo_io = (foo_io); \ \ CLASSERT(offsetof(typeof(*__foo_io), base) == 0); \ memset(&__foo_io->base + 1, 0, \ (sizeof *__foo_io) - sizeof __foo_io->base); \ } while (0) /** @} cl_io */ /** \defgroup cl_page_list cl_page_list * @{ */ /** * Iterate over pages in a page list. */ #define cl_page_list_for_each(page, list) \ cfs_list_for_each_entry((page), &(list)->pl_pages, cp_batch) /** * Iterate over pages in a page list, taking possible removals into account. */ #define cl_page_list_for_each_safe(page, temp, list) \ cfs_list_for_each_entry_safe((page), (temp), &(list)->pl_pages, cp_batch) void cl_page_list_init (struct cl_page_list *plist); void cl_page_list_add (struct cl_page_list *plist, struct cl_page *page); void cl_page_list_move (struct cl_page_list *dst, struct cl_page_list *src, struct cl_page *page); void cl_page_list_splice (struct cl_page_list *list, struct cl_page_list *head); void cl_page_list_del (const struct lu_env *env, struct cl_page_list *plist, struct cl_page *page); void cl_page_list_disown (const struct lu_env *env, struct cl_io *io, struct cl_page_list *plist); int cl_page_list_own (const struct lu_env *env, struct cl_io *io, struct cl_page_list *plist); void cl_page_list_assume (const struct lu_env *env, struct cl_io *io, struct cl_page_list *plist); void cl_page_list_discard(const struct lu_env *env, struct cl_io *io, struct cl_page_list *plist); int cl_page_list_unmap (const struct lu_env *env, struct cl_io *io, struct cl_page_list *plist); void cl_page_list_fini (const struct lu_env *env, struct cl_page_list *plist); void cl_2queue_init (struct cl_2queue *queue); void cl_2queue_add (struct cl_2queue *queue, struct cl_page *page); void cl_2queue_disown (const struct lu_env *env, struct cl_io *io, struct cl_2queue *queue); void cl_2queue_assume (const struct lu_env *env, struct cl_io *io, struct cl_2queue *queue); void cl_2queue_discard (const struct lu_env *env, struct cl_io *io, struct cl_2queue *queue); void cl_2queue_fini (const struct lu_env *env, struct cl_2queue *queue); void cl_2queue_init_page(struct cl_2queue *queue, struct cl_page *page); /** @} cl_page_list */ /** \defgroup cl_req cl_req * @{ */ struct cl_req *cl_req_alloc(const struct lu_env *env, struct cl_page *page, enum cl_req_type crt, int nr_objects); void cl_req_page_add (const struct lu_env *env, struct cl_req *req, struct cl_page *page); void cl_req_page_done (const struct lu_env *env, struct cl_page *page); int cl_req_prep (const struct lu_env *env, struct cl_req *req); void cl_req_attr_set (const struct lu_env *env, struct cl_req *req, struct cl_req_attr *attr, obd_valid flags); void cl_req_completion(const struct lu_env *env, struct cl_req *req, int ioret); /** \defgroup cl_sync_io cl_sync_io * @{ */ /** * Anchor for synchronous transfer. This is allocated on a stack by thread * doing synchronous transfer, and a pointer to this structure is set up in * every page submitted for transfer. Transfer completion routine updates * anchor and wakes up waiting thread when transfer is complete. */ struct cl_sync_io { /** number of pages yet to be transferred. */ cfs_atomic_t csi_sync_nr; /** completion to be signaled when transfer is complete. */ cfs_waitq_t csi_waitq; /** error code. */ int csi_sync_rc; }; void cl_sync_io_init(struct cl_sync_io *anchor, int nrpages); int cl_sync_io_wait(const struct lu_env *env, struct cl_io *io, struct cl_page_list *queue, struct cl_sync_io *anchor, long timeout); void cl_sync_io_note(struct cl_sync_io *anchor, int ioret); /** @} cl_sync_io */ /** @} cl_req */ /** \defgroup cl_env cl_env * * lu_env handling for a client. * * lu_env is an environment within which lustre code executes. Its major part * is lu_context---a fast memory allocation mechanism that is used to conserve * precious kernel stack space. Originally lu_env was designed for a server, * where * * - there is a (mostly) fixed number of threads, and * * - call chains have no non-lustre portions inserted between lustre code. * * On a client both these assumtpion fails, because every user thread can * potentially execute lustre code as part of a system call, and lustre calls * into VFS or MM that call back into lustre. * * To deal with that, cl_env wrapper functions implement the following * optimizations: * * - allocation and destruction of environment is amortized by caching no * longer used environments instead of destroying them; * * - there is a notion of "current" environment, attached to the kernel * data structure representing current thread Top-level lustre code * allocates an environment and makes it current, then calls into * non-lustre code, that in turn calls lustre back. Low-level lustre * code thus called can fetch environment created by the top-level code * and reuse it, avoiding additional environment allocation. * Right now, three interfaces can attach the cl_env to running thread: * - cl_env_get * - cl_env_implant * - cl_env_reexit(cl_env_reenter had to be called priorly) * * \see lu_env, lu_context, lu_context_key * @{ */ struct cl_env_nest { int cen_refcheck; void *cen_cookie; }; struct lu_env *cl_env_peek (int *refcheck); struct lu_env *cl_env_get (int *refcheck); struct lu_env *cl_env_alloc (int *refcheck, __u32 tags); struct lu_env *cl_env_nested_get (struct cl_env_nest *nest); void cl_env_put (struct lu_env *env, int *refcheck); void cl_env_nested_put (struct cl_env_nest *nest, struct lu_env *env); void *cl_env_reenter (void); void cl_env_reexit (void *cookie); void cl_env_implant (struct lu_env *env, int *refcheck); void cl_env_unplant (struct lu_env *env, int *refcheck); unsigned cl_env_cache_purge(unsigned nr); /** @} cl_env */ /* * Misc */ void cl_attr2lvb(struct ost_lvb *lvb, const struct cl_attr *attr); void cl_lvb2attr(struct cl_attr *attr, const struct ost_lvb *lvb); struct cl_device *cl_type_setup(const struct lu_env *env, struct lu_site *site, struct lu_device_type *ldt, struct lu_device *next); /** @} clio */ #endif /* _LINUX_CL_OBJECT_H */