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/*
* 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.
*
* Copyright (c) 2011, 2012, Intel Corporation.
*/
/*
* 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 "lu_object.h"
#include "linux/lustre_compat25.h"
#include <linux/mutex.h>
#include <linux/radix-tree.h>
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;
/** offset of page slice in cl_page buffer */
int co_slice_off;
};
/**
* 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;
/**
* Layout lock handle.
*/
struct ldlm_lock *coc_lock;
/**
* Operation to handle layout, OBJECT_CONF_XYZ.
*/
int coc_opc;
};
enum {
/** configure layout, set up a new stripe, must be called while
* holding layout lock. */
OBJECT_CONF_SET = 0,
/** invalidate the current stripe configuration due to losing
* layout lock. */
OBJECT_CONF_INVALIDATE = 1,
/** wait for old layout to go away so that new layout can be
* set up. */
OBJECT_CONF_WAIT = 2
};
/**
* 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.
*/
int (*coo_page_init)(const struct lu_env *env, struct cl_object *obj,
struct cl_page *page, struct page *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. */
spinlock_t coh_page_guard;
/** Lock protecting lock list. */
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. */
struct list_head 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.
*/
spinlock_t coh_attr_guard;
/**
* Size of cl_page + page slices
*/
unsigned short coh_page_bufsize;
/**
* Number of objects above this one: 0 for a top-object, 1 for its
* sub-object, etc.
*/
unsigned char 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) \
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) \
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), struct page. 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 struct page 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 struct page 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 struct page 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 struct page (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 struct page, 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. */
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. */
struct list_head 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 group. Protected by cl_page::cp_mutex. */
struct list_head cp_batch;
/** Mutex serializing membership of a page in a batch. */
struct mutex cp_mutex;
/** Linkage of pages within cl_req. */
struct list_head 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.
*/
struct task_struct *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. */
struct list_head 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<->struct page 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.
*/
struct page *(*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);
/**
* Write out a page by kernel. This is only called by ll_writepage
* right now.
*
* \see cl_page_flush()
*/
int (*cpo_flush)(const struct lu_env *env,
const struct cl_page_slice *slice,
struct cl_io *io);
/** @} transfer */
};
/**
* Helper macro, dumping detailed information about \a page into a log.
*/
#define CL_PAGE_DEBUG(mask, env, page, format, ...) \
do { \
LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
\
if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
cl_page_print(env, &msgdata, 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 { \
LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
\
if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
cl_page_header_print(env, &msgdata, lu_cdebug_printer, page); \
CDEBUG(mask, format , ## __VA_ARGS__); \
} \
} while (0)
static inline int __page_in_use(const struct cl_page *page, int refc)
{
if (page->cp_type == CPT_CACHEABLE)
++refc;
LASSERT(atomic_read(&page->cp_ref) > 0);
return (atomic_read(&page->cp_ref) > refc);
}
#define cl_page_in_use(pg) __page_in_use(pg, 1)
#define cl_page_in_use_noref(pg) __page_in_use(pg, 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
* example, 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
* <pre>
*
* 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.
* </pre>
* \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,
/** from enqueue RPC reply upcall. */
CLF_FROM_UPCALL= 1 << 3,
};
/**
* 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.
*/
struct list_head 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. */
atomic_t cll_ref;
/** List of slices. Immutable after creation. */
struct list_head cll_layers;
/**
* Linkage into cl_lock::cll_descr::cld_obj::coh_locks list. Protected
* by cl_lock::cll_descr::cld_obj::coh_lock_guard.
*/
struct list_head 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. */
wait_queue_head_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().
*/
struct mutex cll_guard;
struct task_struct *cll_guarder;
int cll_depth;
/**
* the owner for INTRANSIT state
*/
struct task_struct *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
*/
struct list_head 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. */
struct list_head 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,
/** lower layer re-enqueued. */
CLO_REENQUEUED = 3,
};
/**
*
* \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 { \
LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
\
if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
cl_lock_print(env, &msgdata, lu_cdebug_printer, lock); \
CDEBUG(mask, format , ## __VA_ARGS__); \
} \
} while (0)
#define CL_LOCK_ASSERT(expr, env, lock) do { \
if (likely(expr)) \
break; \
\
CL_LOCK_DEBUG(D_ERROR, env, lock, "failed at %s.\n", #expr); \
LBUG(); \
} 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;
struct list_head pl_pages;
struct task_struct *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,
/**
* fsync system call handling
* To write out a range of file
*/
CIT_FSYNC,
/**
* 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
};
/**
* 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.
*/
struct list_head 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);
} 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,
/**
* for async glimpse lock.
*/
CEF_AGL = 0x00000020,
/**
* mask of enq_flags.
*/
CEF_MASK = 0x0000003f,
};
/**
* 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. */
struct list_head 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. */
struct list_head cls_todo;
/** locks currently being processed. */
struct list_head cls_curr;
/** locks acquired. */
struct list_head 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
};
enum cl_fsync_mode {
/** start writeback, do not wait for them to finish */
CL_FSYNC_NONE = 0,
/** start writeback and wait for them to finish */
CL_FSYNC_LOCAL = 1,
/** discard all of dirty pages in a specific file range */
CL_FSYNC_DISCARD = 2,
/** start writeback and make sure they have reached storage before
* return. OST_SYNC RPC must be issued and finished */
CL_FSYNC_ALL = 3
};
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. */
struct list_head 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;
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;
int wr_sync;
} 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? for nopage() only */
int ft_writable;
/** page of an executable? */
int ft_executable;
/** page_mkwrite() */
int ft_mkwrite;
/** resulting page */
struct cl_page *ft_page;
} ci_fault;
struct cl_fsync_io {
loff_t fi_start;
loff_t fi_end;
struct obd_capa *fi_capa;
/** file system level fid */
struct lu_fid *fi_fid;
enum cl_fsync_mode fi_mode;
/* how many pages were written/discarded */
unsigned int fi_nr_written;
} ci_fsync;
} u;
struct cl_2queue ci_queue;
size_t ci_nob;
int ci_result;
unsigned int ci_continue:1,
/**
* This io has held grouplock, to inform sublayers that
* don't do lockless i/o.
*/
ci_no_srvlock:1,
/**
* The whole IO need to be restarted because layout has been changed
*/
ci_need_restart:1,
/**
* to not refresh layout - the IO issuer knows that the layout won't
* change(page operations, layout change causes all page to be
* discarded), or it doesn't matter if it changes(sync).
*/
ci_ignore_layout:1,
/**
* Check if layout changed after the IO finishes. Mainly for HSM
* requirement. If IO occurs to openning files, it doesn't need to
* verify layout because HSM won't release openning files.
* Right now, only two operations need to verify layout: glimpse
* and setattr.
*/
ci_verify_layout:1,
/**
* file is released, restore has to to be triggered by vvp layer
*/
ci_restore_needed:1,
/**
* O_NOATIME
*/
ci_noatime:1;
/**
* 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;
/** Jobid */
char cra_jobid[JOBSTATS_JOBID_SIZE];
};
/**
* 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, u64 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 transferred */
struct list_head 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;
struct list_head crq_layers;
};
/**
* Per-layer state for request.
*/
struct cl_req_slice {
struct cl_req *crs_req;
struct cl_device *crs_dev;
struct list_head crs_linkage;
const struct cl_req_operations *crs_ops;
};
/* @} cl_req */
enum cache_stats_item {
/** how many cache lookups were performed */
CS_lookup = 0,
/** how many times cache lookup resulted in a hit */
CS_hit,
/** how many entities are in the cache right now */
CS_total,
/** how many entities in the cache are actively used (and cannot be
* evicted) right now */
CS_busy,
/** how many entities were created at all */
CS_create,
CS_NR
};
#define CS_NAMES { "lookup", "hit", "total", "busy", "create" }
/**
* Stats for a generic cache (similar to inode, lu_object, etc. caches).
*/
struct cache_stats {
const char *cs_name;
atomic_t cs_stats[CS_NR];
};
/** These are not exported so far */
void cache_stats_init (struct cache_stats *cs, const char *name);
/**
* 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;
atomic_t cs_pages_state[CPS_NR];
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 *site, struct seq_file *m);
/**
* \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);
}
static inline void cl_object_page_init(struct cl_object *clob, int size)
{
clob->co_slice_off = cl_object_header(clob)->coh_page_bufsize;
cl_object_header(clob)->coh_page_bufsize += ALIGN(size, 8);
}
static inline void *cl_object_page_slice(struct cl_object *clob,
struct cl_page *page)
{
return (void *)((char *)page + clob->co_slice_off);
}
/** @} cl_object */
/** \defgroup cl_page cl_page
* @{ */
enum {
CLP_GANG_OKAY = 0,
CLP_GANG_RESCHED,
CLP_GANG_AGAIN,
CLP_GANG_ABORT
};
/* callback of cl_page_gang_lookup() */
typedef int (*cl_page_gang_cb_t) (const struct lu_env *, struct cl_io *,
struct cl_page *, void *);
int cl_page_gang_lookup (const struct lu_env *env,
struct cl_object *obj,
struct cl_io *io,
pgoff_t start, pgoff_t end,
cl_page_gang_cb_t cb, void *cbdata);
struct cl_page *cl_page_lookup (struct cl_object_header *hdr,
pgoff_t index);
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);
struct page *cl_page_vmpage (const struct lu_env *env,
struct cl_page *page);
struct cl_page *cl_vmpage_page (struct page *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);
int cl_page_flush (const struct lu_env *env, struct cl_io *io,
struct cl_page *pg);
/** @} 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_pgoff(const struct lu_env *env,
struct cl_object *obj, pgoff_t index,
struct cl_lock *except, int pending,
int canceld);
static inline 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)
{
LASSERT(cl_object_header(obj) == cl_object_header(page->cp_obj));
return cl_lock_at_pgoff(env, obj, page->cp_index, except,
pending, 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_hold_release(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);
void 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 struct list_head *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_discard_pages(const struct lu_env *env, struct cl_lock *lock);
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);
int cl_io_submit_sync (const struct lu_env *env, struct cl_io *io,
enum cl_req_type iot, struct cl_2queue *queue,
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;
}
static inline int cl_io_is_sync_write(const struct cl_io *io)
{
return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_sync;
}
static inline int cl_io_is_mkwrite(const struct cl_io *io)
{
return io->ci_type == CIT_FAULT && io->u.ci_fault.ft_mkwrite;
}
/**
* 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
* @{ */
/**
* Last page in the page list.
*/
static inline struct cl_page *cl_page_list_last(struct cl_page_list *plist)
{
LASSERT(plist->pl_nr > 0);
return list_entry(plist->pl_pages.prev, struct cl_page, cp_batch);
}
/**
* Iterate over pages in a page list.
*/
#define cl_page_list_for_each(page, list) \
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) \
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, u64 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. */
atomic_t csi_sync_nr;
/** error code. */
int csi_sync_rc;
/** barrier of destroy this structure */
atomic_t csi_barrier;
/** completion to be signaled when transfer is complete. */
wait_queue_head_t csi_waitq;
};
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 assumption 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);
/** @} 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 */
int cl_global_init(void);
void cl_global_fini(void);
#endif /* _LINUX_CL_OBJECT_H */