566 строки
19 KiB
C
566 строки
19 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/* General filesystem caching backing cache interface
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*
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* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* NOTE!!! See:
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*
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* Documentation/filesystems/caching/backend-api.rst
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*
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* for a description of the cache backend interface declared here.
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*/
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#ifndef _LINUX_FSCACHE_CACHE_H
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#define _LINUX_FSCACHE_CACHE_H
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#include <linux/fscache.h>
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#include <linux/sched.h>
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#include <linux/workqueue.h>
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#define NR_MAXCACHES BITS_PER_LONG
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struct fscache_cache;
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struct fscache_cache_ops;
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struct fscache_object;
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struct fscache_operation;
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enum fscache_obj_ref_trace {
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fscache_obj_get_add_to_deps,
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fscache_obj_get_queue,
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fscache_obj_put_alloc_fail,
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fscache_obj_put_attach_fail,
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fscache_obj_put_drop_obj,
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fscache_obj_put_enq_dep,
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fscache_obj_put_queue,
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fscache_obj_put_work,
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fscache_obj_ref__nr_traces
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};
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/*
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* cache tag definition
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*/
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struct fscache_cache_tag {
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struct list_head link;
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struct fscache_cache *cache; /* cache referred to by this tag */
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unsigned long flags;
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#define FSCACHE_TAG_RESERVED 0 /* T if tag is reserved for a cache */
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atomic_t usage;
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char name[]; /* tag name */
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};
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/*
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* cache definition
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*/
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struct fscache_cache {
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const struct fscache_cache_ops *ops;
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struct fscache_cache_tag *tag; /* tag representing this cache */
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struct kobject *kobj; /* system representation of this cache */
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struct list_head link; /* link in list of caches */
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size_t max_index_size; /* maximum size of index data */
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char identifier[36]; /* cache label */
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/* node management */
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struct work_struct op_gc; /* operation garbage collector */
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struct list_head object_list; /* list of data/index objects */
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struct list_head op_gc_list; /* list of ops to be deleted */
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spinlock_t object_list_lock;
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spinlock_t op_gc_list_lock;
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atomic_t object_count; /* no. of live objects in this cache */
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struct fscache_object *fsdef; /* object for the fsdef index */
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unsigned long flags;
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#define FSCACHE_IOERROR 0 /* cache stopped on I/O error */
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#define FSCACHE_CACHE_WITHDRAWN 1 /* cache has been withdrawn */
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};
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extern wait_queue_head_t fscache_cache_cleared_wq;
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/*
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* operation to be applied to a cache object
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* - retrieval initiation operations are done in the context of the process
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* that issued them, and not in an async thread pool
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*/
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typedef void (*fscache_operation_release_t)(struct fscache_operation *op);
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typedef void (*fscache_operation_processor_t)(struct fscache_operation *op);
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typedef void (*fscache_operation_cancel_t)(struct fscache_operation *op);
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enum fscache_operation_state {
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FSCACHE_OP_ST_BLANK, /* Op is not yet submitted */
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FSCACHE_OP_ST_INITIALISED, /* Op is initialised */
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FSCACHE_OP_ST_PENDING, /* Op is blocked from running */
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FSCACHE_OP_ST_IN_PROGRESS, /* Op is in progress */
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FSCACHE_OP_ST_COMPLETE, /* Op is complete */
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FSCACHE_OP_ST_CANCELLED, /* Op has been cancelled */
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FSCACHE_OP_ST_DEAD /* Op is now dead */
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};
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struct fscache_operation {
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struct work_struct work; /* record for async ops */
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struct list_head pend_link; /* link in object->pending_ops */
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struct fscache_object *object; /* object to be operated upon */
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unsigned long flags;
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#define FSCACHE_OP_TYPE 0x000f /* operation type */
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#define FSCACHE_OP_ASYNC 0x0001 /* - async op, processor may sleep for disk */
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#define FSCACHE_OP_MYTHREAD 0x0002 /* - processing is done be issuing thread, not pool */
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#define FSCACHE_OP_WAITING 4 /* cleared when op is woken */
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#define FSCACHE_OP_EXCLUSIVE 5 /* exclusive op, other ops must wait */
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#define FSCACHE_OP_DEC_READ_CNT 6 /* decrement object->n_reads on destruction */
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#define FSCACHE_OP_UNUSE_COOKIE 7 /* call fscache_unuse_cookie() on completion */
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#define FSCACHE_OP_KEEP_FLAGS 0x00f0 /* flags to keep when repurposing an op */
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enum fscache_operation_state state;
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atomic_t usage;
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unsigned debug_id; /* debugging ID */
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/* operation processor callback
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* - can be NULL if FSCACHE_OP_WAITING is going to be used to perform
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* the op in a non-pool thread */
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fscache_operation_processor_t processor;
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/* Operation cancellation cleanup (optional) */
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fscache_operation_cancel_t cancel;
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/* operation releaser */
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fscache_operation_release_t release;
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};
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extern atomic_t fscache_op_debug_id;
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extern void fscache_op_work_func(struct work_struct *work);
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extern void fscache_enqueue_operation(struct fscache_operation *);
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extern void fscache_op_complete(struct fscache_operation *, bool);
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extern void fscache_put_operation(struct fscache_operation *);
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extern void fscache_operation_init(struct fscache_cookie *,
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struct fscache_operation *,
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fscache_operation_processor_t,
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fscache_operation_cancel_t,
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fscache_operation_release_t);
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/*
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* data read operation
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*/
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struct fscache_retrieval {
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struct fscache_operation op;
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struct fscache_cookie *cookie; /* The netfs cookie */
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struct address_space *mapping; /* netfs pages */
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fscache_rw_complete_t end_io_func; /* function to call on I/O completion */
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void *context; /* netfs read context (pinned) */
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struct list_head to_do; /* list of things to be done by the backend */
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atomic_t n_pages; /* number of pages to be retrieved */
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};
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typedef int (*fscache_page_retrieval_func_t)(struct fscache_retrieval *op,
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struct page *page,
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gfp_t gfp);
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typedef int (*fscache_pages_retrieval_func_t)(struct fscache_retrieval *op,
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struct list_head *pages,
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unsigned *nr_pages,
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gfp_t gfp);
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/**
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* fscache_get_retrieval - Get an extra reference on a retrieval operation
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* @op: The retrieval operation to get a reference on
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*
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* Get an extra reference on a retrieval operation.
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*/
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static inline
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struct fscache_retrieval *fscache_get_retrieval(struct fscache_retrieval *op)
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{
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atomic_inc(&op->op.usage);
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return op;
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}
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/**
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* fscache_enqueue_retrieval - Enqueue a retrieval operation for processing
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* @op: The retrieval operation affected
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*
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* Enqueue a retrieval operation for processing by the FS-Cache thread pool.
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*/
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static inline void fscache_enqueue_retrieval(struct fscache_retrieval *op)
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{
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fscache_enqueue_operation(&op->op);
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}
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/**
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* fscache_retrieval_complete - Record (partial) completion of a retrieval
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* @op: The retrieval operation affected
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* @n_pages: The number of pages to account for
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*/
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static inline void fscache_retrieval_complete(struct fscache_retrieval *op,
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int n_pages)
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{
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if (atomic_sub_return_relaxed(n_pages, &op->n_pages) <= 0)
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fscache_op_complete(&op->op, false);
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}
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/**
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* fscache_put_retrieval - Drop a reference to a retrieval operation
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* @op: The retrieval operation affected
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*
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* Drop a reference to a retrieval operation.
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*/
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static inline void fscache_put_retrieval(struct fscache_retrieval *op)
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{
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fscache_put_operation(&op->op);
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}
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/*
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* cached page storage work item
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* - used to do three things:
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* - batch writes to the cache
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* - do cache writes asynchronously
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* - defer writes until cache object lookup completion
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*/
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struct fscache_storage {
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struct fscache_operation op;
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pgoff_t store_limit; /* don't write more than this */
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};
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/*
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* cache operations
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*/
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struct fscache_cache_ops {
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/* name of cache provider */
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const char *name;
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/* allocate an object record for a cookie */
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struct fscache_object *(*alloc_object)(struct fscache_cache *cache,
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struct fscache_cookie *cookie);
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/* look up the object for a cookie
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* - return -ETIMEDOUT to be requeued
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*/
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int (*lookup_object)(struct fscache_object *object);
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/* finished looking up */
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void (*lookup_complete)(struct fscache_object *object);
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/* increment the usage count on this object (may fail if unmounting) */
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struct fscache_object *(*grab_object)(struct fscache_object *object,
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enum fscache_obj_ref_trace why);
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/* pin an object in the cache */
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int (*pin_object)(struct fscache_object *object);
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/* unpin an object in the cache */
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void (*unpin_object)(struct fscache_object *object);
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/* check the consistency between the backing cache and the FS-Cache
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* cookie */
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int (*check_consistency)(struct fscache_operation *op);
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/* store the updated auxiliary data on an object */
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void (*update_object)(struct fscache_object *object);
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/* Invalidate an object */
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void (*invalidate_object)(struct fscache_operation *op);
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/* discard the resources pinned by an object and effect retirement if
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* necessary */
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void (*drop_object)(struct fscache_object *object);
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/* dispose of a reference to an object */
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void (*put_object)(struct fscache_object *object,
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enum fscache_obj_ref_trace why);
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/* sync a cache */
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void (*sync_cache)(struct fscache_cache *cache);
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/* notification that the attributes of a non-index object (such as
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* i_size) have changed */
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int (*attr_changed)(struct fscache_object *object);
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/* reserve space for an object's data and associated metadata */
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int (*reserve_space)(struct fscache_object *object, loff_t i_size);
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/* request a backing block for a page be read or allocated in the
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* cache */
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fscache_page_retrieval_func_t read_or_alloc_page;
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/* request backing blocks for a list of pages be read or allocated in
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* the cache */
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fscache_pages_retrieval_func_t read_or_alloc_pages;
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/* request a backing block for a page be allocated in the cache so that
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* it can be written directly */
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fscache_page_retrieval_func_t allocate_page;
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/* request backing blocks for pages be allocated in the cache so that
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* they can be written directly */
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fscache_pages_retrieval_func_t allocate_pages;
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/* write a page to its backing block in the cache */
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int (*write_page)(struct fscache_storage *op, struct page *page);
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/* detach backing block from a page (optional)
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* - must release the cookie lock before returning
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* - may sleep
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*/
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void (*uncache_page)(struct fscache_object *object,
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struct page *page);
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/* dissociate a cache from all the pages it was backing */
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void (*dissociate_pages)(struct fscache_cache *cache);
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/* Begin a read operation for the netfs lib */
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int (*begin_read_operation)(struct netfs_read_request *rreq,
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struct fscache_retrieval *op);
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};
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extern struct fscache_cookie fscache_fsdef_index;
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/*
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* Event list for fscache_object::{event_mask,events}
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*/
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enum {
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FSCACHE_OBJECT_EV_NEW_CHILD, /* T if object has a new child */
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FSCACHE_OBJECT_EV_PARENT_READY, /* T if object's parent is ready */
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FSCACHE_OBJECT_EV_UPDATE, /* T if object should be updated */
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FSCACHE_OBJECT_EV_INVALIDATE, /* T if cache requested object invalidation */
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FSCACHE_OBJECT_EV_CLEARED, /* T if accessors all gone */
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FSCACHE_OBJECT_EV_ERROR, /* T if fatal error occurred during processing */
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FSCACHE_OBJECT_EV_KILL, /* T if netfs relinquished or cache withdrew object */
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NR_FSCACHE_OBJECT_EVENTS
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};
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#define FSCACHE_OBJECT_EVENTS_MASK ((1UL << NR_FSCACHE_OBJECT_EVENTS) - 1)
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/*
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* States for object state machine.
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*/
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struct fscache_transition {
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unsigned long events;
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const struct fscache_state *transit_to;
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};
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struct fscache_state {
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char name[24];
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char short_name[8];
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const struct fscache_state *(*work)(struct fscache_object *object,
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int event);
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const struct fscache_transition transitions[];
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};
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/*
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* on-disk cache file or index handle
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*/
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struct fscache_object {
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const struct fscache_state *state; /* Object state machine state */
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const struct fscache_transition *oob_table; /* OOB state transition table */
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int debug_id; /* debugging ID */
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int n_children; /* number of child objects */
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int n_ops; /* number of extant ops on object */
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int n_obj_ops; /* number of object ops outstanding on object */
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int n_in_progress; /* number of ops in progress */
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int n_exclusive; /* number of exclusive ops queued or in progress */
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atomic_t n_reads; /* number of read ops in progress */
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spinlock_t lock; /* state and operations lock */
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unsigned long lookup_jif; /* time at which lookup started */
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unsigned long oob_event_mask; /* OOB events this object is interested in */
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unsigned long event_mask; /* events this object is interested in */
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unsigned long events; /* events to be processed by this object
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* (order is important - using fls) */
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unsigned long flags;
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#define FSCACHE_OBJECT_LOCK 0 /* T if object is busy being processed */
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#define FSCACHE_OBJECT_PENDING_WRITE 1 /* T if object has pending write */
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#define FSCACHE_OBJECT_WAITING 2 /* T if object is waiting on its parent */
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#define FSCACHE_OBJECT_IS_LIVE 3 /* T if object is not withdrawn or relinquished */
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#define FSCACHE_OBJECT_IS_LOOKED_UP 4 /* T if object has been looked up */
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#define FSCACHE_OBJECT_IS_AVAILABLE 5 /* T if object has become active */
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#define FSCACHE_OBJECT_RETIRED 6 /* T if object was retired on relinquishment */
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#define FSCACHE_OBJECT_KILLED_BY_CACHE 7 /* T if object was killed by the cache */
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#define FSCACHE_OBJECT_RUN_AFTER_DEAD 8 /* T if object has been dispatched after death */
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struct list_head cache_link; /* link in cache->object_list */
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struct hlist_node cookie_link; /* link in cookie->backing_objects */
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struct fscache_cache *cache; /* cache that supplied this object */
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struct fscache_cookie *cookie; /* netfs's file/index object */
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struct fscache_object *parent; /* parent object */
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struct work_struct work; /* attention scheduling record */
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struct list_head dependents; /* FIFO of dependent objects */
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struct list_head dep_link; /* link in parent's dependents list */
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struct list_head pending_ops; /* unstarted operations on this object */
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pgoff_t store_limit; /* current storage limit */
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loff_t store_limit_l; /* current storage limit */
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};
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extern void fscache_object_init(struct fscache_object *, struct fscache_cookie *,
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struct fscache_cache *);
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extern void fscache_object_destroy(struct fscache_object *);
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extern void fscache_object_lookup_negative(struct fscache_object *object);
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extern void fscache_obtained_object(struct fscache_object *object);
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static inline bool fscache_object_is_live(struct fscache_object *object)
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{
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return test_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags);
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}
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static inline bool fscache_object_is_dying(struct fscache_object *object)
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{
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return !fscache_object_is_live(object);
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}
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static inline bool fscache_object_is_available(struct fscache_object *object)
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{
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return test_bit(FSCACHE_OBJECT_IS_AVAILABLE, &object->flags);
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}
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static inline bool fscache_cache_is_broken(struct fscache_object *object)
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{
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return test_bit(FSCACHE_IOERROR, &object->cache->flags);
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}
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static inline bool fscache_object_is_active(struct fscache_object *object)
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{
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return fscache_object_is_available(object) &&
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fscache_object_is_live(object) &&
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!fscache_cache_is_broken(object);
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}
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/**
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* fscache_object_destroyed - Note destruction of an object in a cache
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* @cache: The cache from which the object came
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*
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* Note the destruction and deallocation of an object record in a cache.
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*/
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static inline void fscache_object_destroyed(struct fscache_cache *cache)
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{
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if (atomic_dec_and_test(&cache->object_count))
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wake_up_all(&fscache_cache_cleared_wq);
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}
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/**
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* fscache_object_lookup_error - Note an object encountered an error
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* @object: The object on which the error was encountered
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*
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* Note that an object encountered a fatal error (usually an I/O error) and
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* that it should be withdrawn as soon as possible.
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*/
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static inline void fscache_object_lookup_error(struct fscache_object *object)
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{
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set_bit(FSCACHE_OBJECT_EV_ERROR, &object->events);
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}
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/**
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* fscache_set_store_limit - Set the maximum size to be stored in an object
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* @object: The object to set the maximum on
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* @i_size: The limit to set in bytes
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*
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* Set the maximum size an object is permitted to reach, implying the highest
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* byte that may be written. Intended to be called by the attr_changed() op.
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*
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* See Documentation/filesystems/caching/backend-api.rst for a complete
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* description.
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*/
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static inline
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void fscache_set_store_limit(struct fscache_object *object, loff_t i_size)
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{
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object->store_limit_l = i_size;
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object->store_limit = i_size >> PAGE_SHIFT;
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if (i_size & ~PAGE_MASK)
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object->store_limit++;
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}
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/**
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* fscache_end_io - End a retrieval operation on a page
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* @op: The FS-Cache operation covering the retrieval
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* @page: The page that was to be fetched
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* @error: The error code (0 if successful)
|
|
*
|
|
* Note the end of an operation to retrieve a page, as covered by a particular
|
|
* operation record.
|
|
*/
|
|
static inline void fscache_end_io(struct fscache_retrieval *op,
|
|
struct page *page, int error)
|
|
{
|
|
op->end_io_func(page, op->context, error);
|
|
}
|
|
|
|
static inline void __fscache_use_cookie(struct fscache_cookie *cookie)
|
|
{
|
|
atomic_inc(&cookie->n_active);
|
|
}
|
|
|
|
/**
|
|
* fscache_use_cookie - Request usage of cookie attached to an object
|
|
* @object: Object description
|
|
*
|
|
* Request usage of the cookie attached to an object. NULL is returned if the
|
|
* relinquishment had reduced the cookie usage count to 0.
|
|
*/
|
|
static inline bool fscache_use_cookie(struct fscache_object *object)
|
|
{
|
|
struct fscache_cookie *cookie = object->cookie;
|
|
return atomic_inc_not_zero(&cookie->n_active) != 0;
|
|
}
|
|
|
|
static inline bool __fscache_unuse_cookie(struct fscache_cookie *cookie)
|
|
{
|
|
return atomic_dec_and_test(&cookie->n_active);
|
|
}
|
|
|
|
static inline void __fscache_wake_unused_cookie(struct fscache_cookie *cookie)
|
|
{
|
|
wake_up_var(&cookie->n_active);
|
|
}
|
|
|
|
/**
|
|
* fscache_unuse_cookie - Cease usage of cookie attached to an object
|
|
* @object: Object description
|
|
*
|
|
* Cease usage of the cookie attached to an object. When the users count
|
|
* reaches zero then the cookie relinquishment will be permitted to proceed.
|
|
*/
|
|
static inline void fscache_unuse_cookie(struct fscache_object *object)
|
|
{
|
|
struct fscache_cookie *cookie = object->cookie;
|
|
if (__fscache_unuse_cookie(cookie))
|
|
__fscache_wake_unused_cookie(cookie);
|
|
}
|
|
|
|
/*
|
|
* out-of-line cache backend functions
|
|
*/
|
|
extern __printf(3, 4)
|
|
void fscache_init_cache(struct fscache_cache *cache,
|
|
const struct fscache_cache_ops *ops,
|
|
const char *idfmt, ...);
|
|
|
|
extern int fscache_add_cache(struct fscache_cache *cache,
|
|
struct fscache_object *fsdef,
|
|
const char *tagname);
|
|
extern void fscache_withdraw_cache(struct fscache_cache *cache);
|
|
|
|
extern void fscache_io_error(struct fscache_cache *cache);
|
|
|
|
extern void fscache_mark_page_cached(struct fscache_retrieval *op,
|
|
struct page *page);
|
|
|
|
extern void fscache_mark_pages_cached(struct fscache_retrieval *op,
|
|
struct pagevec *pagevec);
|
|
|
|
extern bool fscache_object_sleep_till_congested(signed long *timeoutp);
|
|
|
|
extern enum fscache_checkaux fscache_check_aux(struct fscache_object *object,
|
|
const void *data,
|
|
uint16_t datalen,
|
|
loff_t object_size);
|
|
|
|
extern void fscache_object_retrying_stale(struct fscache_object *object);
|
|
|
|
enum fscache_why_object_killed {
|
|
FSCACHE_OBJECT_IS_STALE,
|
|
FSCACHE_OBJECT_NO_SPACE,
|
|
FSCACHE_OBJECT_WAS_RETIRED,
|
|
FSCACHE_OBJECT_WAS_CULLED,
|
|
};
|
|
extern void fscache_object_mark_killed(struct fscache_object *object,
|
|
enum fscache_why_object_killed why);
|
|
|
|
#endif /* _LINUX_FSCACHE_CACHE_H */
|