// SPDX-License-Identifier: GPL-2.0-only /* drbd.c This file is part of DRBD by Philipp Reisner and Lars Ellenberg. Copyright (C) 2001-2008, LINBIT Information Technologies GmbH. Copyright (C) 1999-2008, Philipp Reisner <[email protected]>. Copyright (C) 2002-2008, Lars Ellenberg <[email protected]>. Thanks to Carter Burden, Bart Grantham and Gennadiy Nerubayev from Logicworks, Inc. for making SDP replication support possible. */ #define pr_fmt(fmt) … #include <linux/module.h> #include <linux/jiffies.h> #include <linux/drbd.h> #include <linux/uaccess.h> #include <asm/types.h> #include <net/sock.h> #include <linux/ctype.h> #include <linux/mutex.h> #include <linux/fs.h> #include <linux/file.h> #include <linux/proc_fs.h> #include <linux/init.h> #include <linux/mm.h> #include <linux/memcontrol.h> #include <linux/mm_inline.h> #include <linux/slab.h> #include <linux/random.h> #include <linux/reboot.h> #include <linux/notifier.h> #include <linux/kthread.h> #include <linux/workqueue.h> #include <linux/unistd.h> #include <linux/vmalloc.h> #include <linux/sched/signal.h> #include <linux/drbd_limits.h> #include "drbd_int.h" #include "drbd_protocol.h" #include "drbd_req.h" /* only for _req_mod in tl_release and tl_clear */ #include "drbd_vli.h" #include "drbd_debugfs.h" static DEFINE_MUTEX(drbd_main_mutex); static int drbd_open(struct gendisk *disk, blk_mode_t mode); static void drbd_release(struct gendisk *gd); static void md_sync_timer_fn(struct timer_list *t); static int w_bitmap_io(struct drbd_work *w, int unused); MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …; MODULE_VERSION(…); MODULE_LICENSE(…) …; MODULE_PARM_DESC(…) …; MODULE_ALIAS_BLOCKDEV_MAJOR(…); #include <linux/moduleparam.h> /* thanks to these macros, if compiled into the kernel (not-module), * these become boot parameters (e.g., drbd.minor_count) */ #ifdef CONFIG_DRBD_FAULT_INJECTION int drbd_enable_faults; int drbd_fault_rate; static int drbd_fault_count; static int drbd_fault_devs; /* bitmap of enabled faults */ module_param_named(enable_faults, drbd_enable_faults, int, 0664); /* fault rate % value - applies to all enabled faults */ module_param_named(fault_rate, drbd_fault_rate, int, 0664); /* count of faults inserted */ module_param_named(fault_count, drbd_fault_count, int, 0664); /* bitmap of devices to insert faults on */ module_param_named(fault_devs, drbd_fault_devs, int, 0644); #endif /* module parameters we can keep static */ static bool drbd_allow_oos; /* allow_open_on_secondary */ static bool drbd_disable_sendpage; MODULE_PARM_DESC(…) …; module_param_named(allow_oos, drbd_allow_oos, bool, 0); module_param_named(disable_sendpage, drbd_disable_sendpage, bool, 0644); /* module parameters we share */ int drbd_proc_details; /* Detail level in proc drbd*/ module_param_named(proc_details, drbd_proc_details, int, 0644); /* module parameters shared with defaults */ unsigned int drbd_minor_count = …; /* Module parameter for setting the user mode helper program * to run. Default is /sbin/drbdadm */ char drbd_usermode_helper[80] = …; module_param_named(minor_count, drbd_minor_count, uint, 0444); module_param_string(…); /* in 2.6.x, our device mapping and config info contains our virtual gendisks * as member "struct gendisk *vdisk;" */ struct idr drbd_devices; struct list_head drbd_resources; struct mutex resources_mutex; struct kmem_cache *drbd_request_cache; struct kmem_cache *drbd_ee_cache; /* peer requests */ struct kmem_cache *drbd_bm_ext_cache; /* bitmap extents */ struct kmem_cache *drbd_al_ext_cache; /* activity log extents */ mempool_t drbd_request_mempool; mempool_t drbd_ee_mempool; mempool_t drbd_md_io_page_pool; struct bio_set drbd_md_io_bio_set; struct bio_set drbd_io_bio_set; /* I do not use a standard mempool, because: 1) I want to hand out the pre-allocated objects first. 2) I want to be able to interrupt sleeping allocation with a signal. Note: This is a single linked list, the next pointer is the private member of struct page. */ struct page *drbd_pp_pool; DEFINE_SPINLOCK(…); int drbd_pp_vacant; wait_queue_head_t drbd_pp_wait; DEFINE_RATELIMIT_STATE(…); static const struct block_device_operations drbd_ops = …; #ifdef __CHECKER__ /* When checking with sparse, and this is an inline function, sparse will give tons of false positives. When this is a real functions sparse works. */ int _get_ldev_if_state(struct drbd_device *device, enum drbd_disk_state mins) { int io_allowed; atomic_inc(&device->local_cnt); io_allowed = (device->state.disk >= mins); if (!io_allowed) { if (atomic_dec_and_test(&device->local_cnt)) wake_up(&device->misc_wait); } return io_allowed; } #endif /** * tl_release() - mark as BARRIER_ACKED all requests in the corresponding transfer log epoch * @connection: DRBD connection. * @barrier_nr: Expected identifier of the DRBD write barrier packet. * @set_size: Expected number of requests before that barrier. * * In case the passed barrier_nr or set_size does not match the oldest * epoch of not yet barrier-acked requests, this function will cause a * termination of the connection. */ void tl_release(struct drbd_connection *connection, unsigned int barrier_nr, unsigned int set_size) { … } /** * _tl_restart() - Walks the transfer log, and applies an action to all requests * @connection: DRBD connection to operate on. * @what: The action/event to perform with all request objects * * @what might be one of CONNECTION_LOST_WHILE_PENDING, RESEND, FAIL_FROZEN_DISK_IO, * RESTART_FROZEN_DISK_IO. */ /* must hold resource->req_lock */ void _tl_restart(struct drbd_connection *connection, enum drbd_req_event what) { … } void tl_restart(struct drbd_connection *connection, enum drbd_req_event what) { … } /** * tl_clear() - Clears all requests and &struct drbd_tl_epoch objects out of the TL * @connection: DRBD connection. * * This is called after the connection to the peer was lost. The storage covered * by the requests on the transfer gets marked as our of sync. Called from the * receiver thread and the worker thread. */ void tl_clear(struct drbd_connection *connection) { … } /** * tl_abort_disk_io() - Abort disk I/O for all requests for a certain device in the TL * @device: DRBD device. */ void tl_abort_disk_io(struct drbd_device *device) { … } static int drbd_thread_setup(void *arg) { … } static void drbd_thread_init(struct drbd_resource *resource, struct drbd_thread *thi, int (*func) (struct drbd_thread *), const char *name) { … } int drbd_thread_start(struct drbd_thread *thi) { … } void _drbd_thread_stop(struct drbd_thread *thi, int restart, int wait) { … } #ifdef CONFIG_SMP /* * drbd_calc_cpu_mask() - Generate CPU masks, spread over all CPUs * * Forces all threads of a resource onto the same CPU. This is beneficial for * DRBD's performance. May be overwritten by user's configuration. */ static void drbd_calc_cpu_mask(cpumask_var_t *cpu_mask) { … } /** * drbd_thread_current_set_cpu() - modifies the cpu mask of the _current_ thread * @thi: drbd_thread object * * call in the "main loop" of _all_ threads, no need for any mutex, current won't die * prematurely. */ void drbd_thread_current_set_cpu(struct drbd_thread *thi) { … } #else #define drbd_calc_cpu_mask … #endif /* * drbd_header_size - size of a packet header * * The header size is a multiple of 8, so any payload following the header is * word aligned on 64-bit architectures. (The bitmap send and receive code * relies on this.) */ unsigned int drbd_header_size(struct drbd_connection *connection) { … } static unsigned int prepare_header80(struct p_header80 *h, enum drbd_packet cmd, int size) { … } static unsigned int prepare_header95(struct p_header95 *h, enum drbd_packet cmd, int size) { … } static unsigned int prepare_header100(struct p_header100 *h, enum drbd_packet cmd, int size, int vnr) { … } static unsigned int prepare_header(struct drbd_connection *connection, int vnr, void *buffer, enum drbd_packet cmd, int size) { … } static void *__conn_prepare_command(struct drbd_connection *connection, struct drbd_socket *sock) { … } void *conn_prepare_command(struct drbd_connection *connection, struct drbd_socket *sock) { … } void *drbd_prepare_command(struct drbd_peer_device *peer_device, struct drbd_socket *sock) { … } static int __send_command(struct drbd_connection *connection, int vnr, struct drbd_socket *sock, enum drbd_packet cmd, unsigned int header_size, void *data, unsigned int size) { … } static int __conn_send_command(struct drbd_connection *connection, struct drbd_socket *sock, enum drbd_packet cmd, unsigned int header_size, void *data, unsigned int size) { … } int conn_send_command(struct drbd_connection *connection, struct drbd_socket *sock, enum drbd_packet cmd, unsigned int header_size, void *data, unsigned int size) { … } int drbd_send_command(struct drbd_peer_device *peer_device, struct drbd_socket *sock, enum drbd_packet cmd, unsigned int header_size, void *data, unsigned int size) { … } int drbd_send_ping(struct drbd_connection *connection) { … } int drbd_send_ping_ack(struct drbd_connection *connection) { … } int drbd_send_sync_param(struct drbd_peer_device *peer_device) { … } int __drbd_send_protocol(struct drbd_connection *connection, enum drbd_packet cmd) { … } int drbd_send_protocol(struct drbd_connection *connection) { … } static int _drbd_send_uuids(struct drbd_peer_device *peer_device, u64 uuid_flags) { … } int drbd_send_uuids(struct drbd_peer_device *peer_device) { … } int drbd_send_uuids_skip_initial_sync(struct drbd_peer_device *peer_device) { … } void drbd_print_uuids(struct drbd_device *device, const char *text) { … } void drbd_gen_and_send_sync_uuid(struct drbd_peer_device *peer_device) { … } int drbd_send_sizes(struct drbd_peer_device *peer_device, int trigger_reply, enum dds_flags flags) { … } /** * drbd_send_current_state() - Sends the drbd state to the peer * @peer_device: DRBD peer device. */ int drbd_send_current_state(struct drbd_peer_device *peer_device) { … } /** * drbd_send_state() - After a state change, sends the new state to the peer * @peer_device: DRBD peer device. * @state: the state to send, not necessarily the current state. * * Each state change queues an "after_state_ch" work, which will eventually * send the resulting new state to the peer. If more state changes happen * between queuing and processing of the after_state_ch work, we still * want to send each intermediary state in the order it occurred. */ int drbd_send_state(struct drbd_peer_device *peer_device, union drbd_state state) { … } int drbd_send_state_req(struct drbd_peer_device *peer_device, union drbd_state mask, union drbd_state val) { … } int conn_send_state_req(struct drbd_connection *connection, union drbd_state mask, union drbd_state val) { … } void drbd_send_sr_reply(struct drbd_peer_device *peer_device, enum drbd_state_rv retcode) { … } void conn_send_sr_reply(struct drbd_connection *connection, enum drbd_state_rv retcode) { … } static void dcbp_set_code(struct p_compressed_bm *p, enum drbd_bitmap_code code) { … } static void dcbp_set_start(struct p_compressed_bm *p, int set) { … } static void dcbp_set_pad_bits(struct p_compressed_bm *p, int n) { … } static int fill_bitmap_rle_bits(struct drbd_device *device, struct p_compressed_bm *p, unsigned int size, struct bm_xfer_ctx *c) { … } /* * send_bitmap_rle_or_plain * * Return 0 when done, 1 when another iteration is needed, and a negative error * code upon failure. */ static int send_bitmap_rle_or_plain(struct drbd_peer_device *peer_device, struct bm_xfer_ctx *c) { … } /* See the comment at receive_bitmap() */ static int _drbd_send_bitmap(struct drbd_device *device, struct drbd_peer_device *peer_device) { … } int drbd_send_bitmap(struct drbd_device *device, struct drbd_peer_device *peer_device) { … } void drbd_send_b_ack(struct drbd_connection *connection, u32 barrier_nr, u32 set_size) { … } /** * _drbd_send_ack() - Sends an ack packet * @peer_device: DRBD peer device. * @cmd: Packet command code. * @sector: sector, needs to be in big endian byte order * @blksize: size in byte, needs to be in big endian byte order * @block_id: Id, big endian byte order */ static int _drbd_send_ack(struct drbd_peer_device *peer_device, enum drbd_packet cmd, u64 sector, u32 blksize, u64 block_id) { … } /* dp->sector and dp->block_id already/still in network byte order, * data_size is payload size according to dp->head, * and may need to be corrected for digest size. */ void drbd_send_ack_dp(struct drbd_peer_device *peer_device, enum drbd_packet cmd, struct p_data *dp, int data_size) { … } void drbd_send_ack_rp(struct drbd_peer_device *peer_device, enum drbd_packet cmd, struct p_block_req *rp) { … } /** * drbd_send_ack() - Sends an ack packet * @peer_device: DRBD peer device * @cmd: packet command code * @peer_req: peer request */ int drbd_send_ack(struct drbd_peer_device *peer_device, enum drbd_packet cmd, struct drbd_peer_request *peer_req) { … } /* This function misuses the block_id field to signal if the blocks * are is sync or not. */ int drbd_send_ack_ex(struct drbd_peer_device *peer_device, enum drbd_packet cmd, sector_t sector, int blksize, u64 block_id) { … } int drbd_send_rs_deallocated(struct drbd_peer_device *peer_device, struct drbd_peer_request *peer_req) { … } int drbd_send_drequest(struct drbd_peer_device *peer_device, int cmd, sector_t sector, int size, u64 block_id) { … } int drbd_send_drequest_csum(struct drbd_peer_device *peer_device, sector_t sector, int size, void *digest, int digest_size, enum drbd_packet cmd) { … } int drbd_send_ov_request(struct drbd_peer_device *peer_device, sector_t sector, int size) { … } /* called on sndtimeo * returns false if we should retry, * true if we think connection is dead */ static int we_should_drop_the_connection(struct drbd_connection *connection, struct socket *sock) { … } static void drbd_update_congested(struct drbd_connection *connection) { … } /* The idea of sendpage seems to be to put some kind of reference * to the page into the skb, and to hand it over to the NIC. In * this process get_page() gets called. * * As soon as the page was really sent over the network put_page() * gets called by some part of the network layer. [ NIC driver? ] * * [ get_page() / put_page() increment/decrement the count. If count * reaches 0 the page will be freed. ] * * This works nicely with pages from FSs. * But this means that in protocol A we might signal IO completion too early! * * In order not to corrupt data during a resync we must make sure * that we do not reuse our own buffer pages (EEs) to early, therefore * we have the net_ee list. * * XFS seems to have problems, still, it submits pages with page_count == 0! * As a workaround, we disable sendpage on pages * with page_count == 0 or PageSlab. */ static int _drbd_no_send_page(struct drbd_peer_device *peer_device, struct page *page, int offset, size_t size, unsigned msg_flags) { … } static int _drbd_send_page(struct drbd_peer_device *peer_device, struct page *page, int offset, size_t size, unsigned msg_flags) { … } static int _drbd_send_bio(struct drbd_peer_device *peer_device, struct bio *bio) { … } static int _drbd_send_zc_bio(struct drbd_peer_device *peer_device, struct bio *bio) { … } static int _drbd_send_zc_ee(struct drbd_peer_device *peer_device, struct drbd_peer_request *peer_req) { … } static u32 bio_flags_to_wire(struct drbd_connection *connection, struct bio *bio) { … } /* Used to send write or TRIM aka REQ_OP_DISCARD requests * R_PRIMARY -> Peer (P_DATA, P_TRIM) */ int drbd_send_dblock(struct drbd_peer_device *peer_device, struct drbd_request *req) { … } /* answer packet, used to send data back for read requests: * Peer -> (diskless) R_PRIMARY (P_DATA_REPLY) * C_SYNC_SOURCE -> C_SYNC_TARGET (P_RS_DATA_REPLY) */ int drbd_send_block(struct drbd_peer_device *peer_device, enum drbd_packet cmd, struct drbd_peer_request *peer_req) { … } int drbd_send_out_of_sync(struct drbd_peer_device *peer_device, struct drbd_request *req) { … } /* drbd_send distinguishes two cases: Packets sent via the data socket "sock" and packets sent via the meta data socket "msock" sock msock -----------------+-------------------------+------------------------------ timeout conf.timeout / 2 conf.timeout / 2 timeout action send a ping via msock Abort communication and close all sockets */ /* * you must have down()ed the appropriate [m]sock_mutex elsewhere! */ int drbd_send(struct drbd_connection *connection, struct socket *sock, void *buf, size_t size, unsigned msg_flags) { … } /* * drbd_send_all - Send an entire buffer * * Returns 0 upon success and a negative error value otherwise. */ int drbd_send_all(struct drbd_connection *connection, struct socket *sock, void *buffer, size_t size, unsigned msg_flags) { … } static int drbd_open(struct gendisk *disk, blk_mode_t mode) { … } static void drbd_release(struct gendisk *gd) { … } /* need to hold resource->req_lock */ void drbd_queue_unplug(struct drbd_device *device) { … } static void drbd_set_defaults(struct drbd_device *device) { … } void drbd_init_set_defaults(struct drbd_device *device) { … } void drbd_set_my_capacity(struct drbd_device *device, sector_t size) { … } void drbd_device_cleanup(struct drbd_device *device) { … } static void drbd_destroy_mempools(void) { … } static int drbd_create_mempools(void) { … } static void drbd_release_all_peer_reqs(struct drbd_device *device) { … } /* caution. no locking. */ void drbd_destroy_device(struct kref *kref) { … } /* One global retry thread, if we need to push back some bio and have it * reinserted through our make request function. */ static struct retry_worker { … } retry; static void do_retry(struct work_struct *ws) { … } /* called via drbd_req_put_completion_ref(), * holds resource->req_lock */ void drbd_restart_request(struct drbd_request *req) { … } void drbd_destroy_resource(struct kref *kref) { … } void drbd_free_resource(struct drbd_resource *resource) { … } static void drbd_cleanup(void) { … } static void drbd_init_workqueue(struct drbd_work_queue* wq) { … } struct completion_work { … }; static int w_complete(struct drbd_work *w, int cancel) { … } void drbd_flush_workqueue(struct drbd_work_queue *work_queue) { … } struct drbd_resource *drbd_find_resource(const char *name) { … } struct drbd_connection *conn_get_by_addrs(void *my_addr, int my_addr_len, void *peer_addr, int peer_addr_len) { … } static int drbd_alloc_socket(struct drbd_socket *socket) { … } static void drbd_free_socket(struct drbd_socket *socket) { … } void conn_free_crypto(struct drbd_connection *connection) { … } int set_resource_options(struct drbd_resource *resource, struct res_opts *res_opts) { … } struct drbd_resource *drbd_create_resource(const char *name) { … } /* caller must be under adm_mutex */ struct drbd_connection *conn_create(const char *name, struct res_opts *res_opts) { … } void drbd_destroy_connection(struct kref *kref) { … } static int init_submitter(struct drbd_device *device) { … } enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsigned int minor) { … } void drbd_delete_device(struct drbd_device *device) { … } static int __init drbd_init(void) { … } static void drbd_free_one_sock(struct drbd_socket *ds) { … } void drbd_free_sock(struct drbd_connection *connection) { … } /* meta data management */ void conn_md_sync(struct drbd_connection *connection) { … } /* aligned 4kByte */ struct meta_data_on_disk { … } __packed; void drbd_md_write(struct drbd_device *device, void *b) { … } /** * drbd_md_sync() - Writes the meta data super block if the MD_DIRTY flag bit is set * @device: DRBD device. */ void drbd_md_sync(struct drbd_device *device) { … } static int check_activity_log_stripe_size(struct drbd_device *device, struct meta_data_on_disk *on_disk, struct drbd_md *in_core) { … } static int check_offsets_and_sizes(struct drbd_device *device, struct drbd_backing_dev *bdev) { … } /** * drbd_md_read() - Reads in the meta data super block * @device: DRBD device. * @bdev: Device from which the meta data should be read in. * * Return NO_ERROR on success, and an enum drbd_ret_code in case * something goes wrong. * * Called exactly once during drbd_adm_attach(), while still being D_DISKLESS, * even before @bdev is assigned to @device->ldev. */ int drbd_md_read(struct drbd_device *device, struct drbd_backing_dev *bdev) { … } /** * drbd_md_mark_dirty() - Mark meta data super block as dirty * @device: DRBD device. * * Call this function if you change anything that should be written to * the meta-data super block. This function sets MD_DIRTY, and starts a * timer that ensures that within five seconds you have to call drbd_md_sync(). */ void drbd_md_mark_dirty(struct drbd_device *device) { … } void drbd_uuid_move_history(struct drbd_device *device) __must_hold(local) { … } void __drbd_uuid_set(struct drbd_device *device, int idx, u64 val) __must_hold(local) { … } void _drbd_uuid_set(struct drbd_device *device, int idx, u64 val) __must_hold(local) { … } void drbd_uuid_set(struct drbd_device *device, int idx, u64 val) __must_hold(local) { … } /** * drbd_uuid_new_current() - Creates a new current UUID * @device: DRBD device. * * Creates a new current UUID, and rotates the old current UUID into * the bitmap slot. Causes an incremental resync upon next connect. */ void drbd_uuid_new_current(struct drbd_device *device) __must_hold(local) { … } void drbd_uuid_set_bm(struct drbd_device *device, u64 val) __must_hold(local) { … } /** * drbd_bmio_set_n_write() - io_fn for drbd_queue_bitmap_io() or drbd_bitmap_io() * @device: DRBD device. * @peer_device: Peer DRBD device. * * Sets all bits in the bitmap and writes the whole bitmap to stable storage. */ int drbd_bmio_set_n_write(struct drbd_device *device, struct drbd_peer_device *peer_device) __must_hold(local) { … } /** * drbd_bmio_clear_n_write() - io_fn for drbd_queue_bitmap_io() or drbd_bitmap_io() * @device: DRBD device. * @peer_device: Peer DRBD device. * * Clears all bits in the bitmap and writes the whole bitmap to stable storage. */ int drbd_bmio_clear_n_write(struct drbd_device *device, struct drbd_peer_device *peer_device) __must_hold(local) { … } static int w_bitmap_io(struct drbd_work *w, int unused) { … } /** * drbd_queue_bitmap_io() - Queues an IO operation on the whole bitmap * @device: DRBD device. * @io_fn: IO callback to be called when bitmap IO is possible * @done: callback to be called after the bitmap IO was performed * @why: Descriptive text of the reason for doing the IO * @flags: Bitmap flags * @peer_device: Peer DRBD device. * * While IO on the bitmap happens we freeze application IO thus we ensure * that drbd_set_out_of_sync() can not be called. This function MAY ONLY be * called from worker context. It MUST NOT be used while a previous such * work is still pending! * * Its worker function encloses the call of io_fn() by get_ldev() and * put_ldev(). */ void drbd_queue_bitmap_io(struct drbd_device *device, int (*io_fn)(struct drbd_device *, struct drbd_peer_device *), void (*done)(struct drbd_device *, int), char *why, enum bm_flag flags, struct drbd_peer_device *peer_device) { … } /** * drbd_bitmap_io() - Does an IO operation on the whole bitmap * @device: DRBD device. * @io_fn: IO callback to be called when bitmap IO is possible * @why: Descriptive text of the reason for doing the IO * @flags: Bitmap flags * @peer_device: Peer DRBD device. * * freezes application IO while that the actual IO operations runs. This * functions MAY NOT be called from worker context. */ int drbd_bitmap_io(struct drbd_device *device, int (*io_fn)(struct drbd_device *, struct drbd_peer_device *), char *why, enum bm_flag flags, struct drbd_peer_device *peer_device) { … } void drbd_md_set_flag(struct drbd_device *device, int flag) __must_hold(local) { … } void drbd_md_clear_flag(struct drbd_device *device, int flag) __must_hold(local) { … } int drbd_md_test_flag(struct drbd_backing_dev *bdev, int flag) { … } static void md_sync_timer_fn(struct timer_list *t) { … } const char *cmdname(enum drbd_packet cmd) { … } /** * drbd_wait_misc - wait for a request to make progress * @device: device associated with the request * @i: the struct drbd_interval embedded in struct drbd_request or * struct drbd_peer_request */ int drbd_wait_misc(struct drbd_device *device, struct drbd_interval *i) { … } void lock_all_resources(void) { … } void unlock_all_resources(void) { … } #ifdef CONFIG_DRBD_FAULT_INJECTION /* Fault insertion support including random number generator shamelessly * stolen from kernel/rcutorture.c */ struct fault_random_state { … }; #define FAULT_RANDOM_MULT … #define FAULT_RANDOM_ADD … #define FAULT_RANDOM_REFRESH … /* * Crude but fast random-number generator. Uses a linear congruential * generator, with occasional help from get_random_bytes(). */ static unsigned long _drbd_fault_random(struct fault_random_state *rsp) { … } static char * _drbd_fault_str(unsigned int type) { … } unsigned int _drbd_insert_fault(struct drbd_device *device, unsigned int type) { … } #endif module_init(…) … module_exit(…) EXPORT_SYMBOL(…); EXPORT_SYMBOL(…); EXPORT_SYMBOL(…); EXPORT_SYMBOL(…);
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