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linux-stable/drivers/block/nbd.c
David Howells aa563d7bca iov_iter: Separate type from direction and use accessor functions 
In the iov_iter struct, separate the iterator type from the iterator
direction and use accessor functions to access them in most places.

Convert a bunch of places to use switch-statements to access them rather
then chains of bitwise-AND statements.  This makes it easier to add further
iterator types.  Also, this can be more efficient as to implement a switch
of small contiguous integers, the compiler can use ~50% fewer compare
instructions than it has to use bitwise-and instructions.

Further, cease passing the iterator type into the iterator setup function.
The iterator function can set that itself.  Only the direction is required.

Signed-off-by: David Howells <dhowells@redhat.com>
2018-10-24 00:41:07 +01:00

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/*
* Network block device - make block devices work over TCP
*
* Note that you can not swap over this thing, yet. Seems to work but
* deadlocks sometimes - you can not swap over TCP in general.
*
* Copyright 1997-2000, 2008 Pavel Machek <pavel@ucw.cz>
* Parts copyright 2001 Steven Whitehouse <steve@chygwyn.com>
*
* This file is released under GPLv2 or later.
*
* (part of code stolen from loop.c)
*/
#include <linux/major.h>
#include <linux/blkdev.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/fs.h>
#include <linux/bio.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/ioctl.h>
#include <linux/mutex.h>
#include <linux/compiler.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <linux/net.h>
#include <linux/kthread.h>
#include <linux/types.h>
#include <linux/debugfs.h>
#include <linux/blk-mq.h>
#include <linux/uaccess.h>
#include <asm/types.h>
#include <linux/nbd.h>
#include <linux/nbd-netlink.h>
#include <net/genetlink.h>
static DEFINE_IDR(nbd_index_idr);
static DEFINE_MUTEX(nbd_index_mutex);
static int nbd_total_devices = 0;
struct nbd_sock {
struct socket *sock;
struct mutex tx_lock;
struct request *pending;
int sent;
bool dead;
int fallback_index;
int cookie;
};
struct recv_thread_args {
struct work_struct work;
struct nbd_device *nbd;
int index;
};
struct link_dead_args {
struct work_struct work;
int index;
};
#define NBD_TIMEDOUT 0
#define NBD_DISCONNECT_REQUESTED 1
#define NBD_DISCONNECTED 2
#define NBD_HAS_PID_FILE 3
#define NBD_HAS_CONFIG_REF 4
#define NBD_BOUND 5
#define NBD_DESTROY_ON_DISCONNECT 6
#define NBD_DISCONNECT_ON_CLOSE 7
struct nbd_config {
u32 flags;
unsigned long runtime_flags;
u64 dead_conn_timeout;
struct nbd_sock **socks;
int num_connections;
atomic_t live_connections;
wait_queue_head_t conn_wait;
atomic_t recv_threads;
wait_queue_head_t recv_wq;
loff_t blksize;
loff_t bytesize;
#if IS_ENABLED(CONFIG_DEBUG_FS)
struct dentry *dbg_dir;
#endif
};
struct nbd_device {
struct blk_mq_tag_set tag_set;
int index;
refcount_t config_refs;
refcount_t refs;
struct nbd_config *config;
struct mutex config_lock;
struct gendisk *disk;
struct list_head list;
struct task_struct *task_recv;
struct task_struct *task_setup;
};
#define NBD_CMD_REQUEUED 1
struct nbd_cmd {
struct nbd_device *nbd;
struct mutex lock;
int index;
int cookie;
blk_status_t status;
unsigned long flags;
u32 cmd_cookie;
};
#if IS_ENABLED(CONFIG_DEBUG_FS)
static struct dentry *nbd_dbg_dir;
#endif
#define nbd_name(nbd) ((nbd)->disk->disk_name)
#define NBD_MAGIC 0x68797548
static unsigned int nbds_max = 16;
static int max_part = 16;
static struct workqueue_struct *recv_workqueue;
static int part_shift;
static int nbd_dev_dbg_init(struct nbd_device *nbd);
static void nbd_dev_dbg_close(struct nbd_device *nbd);
static void nbd_config_put(struct nbd_device *nbd);
static void nbd_connect_reply(struct genl_info *info, int index);
static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info);
static void nbd_dead_link_work(struct work_struct *work);
static void nbd_disconnect_and_put(struct nbd_device *nbd);
static inline struct device *nbd_to_dev(struct nbd_device *nbd)
{
return disk_to_dev(nbd->disk);
}
static void nbd_requeue_cmd(struct nbd_cmd *cmd)
{
struct request *req = blk_mq_rq_from_pdu(cmd);
if (!test_and_set_bit(NBD_CMD_REQUEUED, &cmd->flags))
blk_mq_requeue_request(req, true);
}
#define NBD_COOKIE_BITS 32
static u64 nbd_cmd_handle(struct nbd_cmd *cmd)
{
struct request *req = blk_mq_rq_from_pdu(cmd);
u32 tag = blk_mq_unique_tag(req);
u64 cookie = cmd->cmd_cookie;
return (cookie << NBD_COOKIE_BITS) | tag;
}
static u32 nbd_handle_to_tag(u64 handle)
{
return (u32)handle;
}
static u32 nbd_handle_to_cookie(u64 handle)
{
return (u32)(handle >> NBD_COOKIE_BITS);
}
static const char *nbdcmd_to_ascii(int cmd)
{
switch (cmd) {
case NBD_CMD_READ: return "read";
case NBD_CMD_WRITE: return "write";
case NBD_CMD_DISC: return "disconnect";
case NBD_CMD_FLUSH: return "flush";
case NBD_CMD_TRIM: return "trim/discard";
}
return "invalid";
}
static ssize_t pid_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
struct nbd_device *nbd = (struct nbd_device *)disk->private_data;
return sprintf(buf, "%d\n", task_pid_nr(nbd->task_recv));
}
static const struct device_attribute pid_attr = {
.attr = { .name = "pid", .mode = 0444},
.show = pid_show,
};
static void nbd_dev_remove(struct nbd_device *nbd)
{
struct gendisk *disk = nbd->disk;
struct request_queue *q;
if (disk) {
q = disk->queue;
del_gendisk(disk);
blk_cleanup_queue(q);
blk_mq_free_tag_set(&nbd->tag_set);
disk->private_data = NULL;
put_disk(disk);
}
kfree(nbd);
}
static void nbd_put(struct nbd_device *nbd)
{
if (refcount_dec_and_mutex_lock(&nbd->refs,
&nbd_index_mutex)) {
idr_remove(&nbd_index_idr, nbd->index);
mutex_unlock(&nbd_index_mutex);
nbd_dev_remove(nbd);
}
}
static int nbd_disconnected(struct nbd_config *config)
{
return test_bit(NBD_DISCONNECTED, &config->runtime_flags) ||
test_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags);
}
static void nbd_mark_nsock_dead(struct nbd_device *nbd, struct nbd_sock *nsock,
int notify)
{
if (!nsock->dead && notify && !nbd_disconnected(nbd->config)) {
struct link_dead_args *args;
args = kmalloc(sizeof(struct link_dead_args), GFP_NOIO);
if (args) {
INIT_WORK(&args->work, nbd_dead_link_work);
args->index = nbd->index;
queue_work(system_wq, &args->work);
}
}
if (!nsock->dead) {
kernel_sock_shutdown(nsock->sock, SHUT_RDWR);
if (atomic_dec_return(&nbd->config->live_connections) == 0) {
if (test_and_clear_bit(NBD_DISCONNECT_REQUESTED,
&nbd->config->runtime_flags)) {
set_bit(NBD_DISCONNECTED,
&nbd->config->runtime_flags);
dev_info(nbd_to_dev(nbd),
"Disconnected due to user request.\n");
}
}
}
nsock->dead = true;
nsock->pending = NULL;
nsock->sent = 0;
}
static void nbd_size_clear(struct nbd_device *nbd)
{
if (nbd->config->bytesize) {
set_capacity(nbd->disk, 0);
kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
}
}
static void nbd_size_update(struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
struct block_device *bdev = bdget_disk(nbd->disk, 0);
if (config->flags & NBD_FLAG_SEND_TRIM) {
nbd->disk->queue->limits.discard_granularity = config->blksize;
nbd->disk->queue->limits.discard_alignment = config->blksize;
blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
}
blk_queue_logical_block_size(nbd->disk->queue, config->blksize);
blk_queue_physical_block_size(nbd->disk->queue, config->blksize);
set_capacity(nbd->disk, config->bytesize >> 9);
if (bdev) {
if (bdev->bd_disk)
bd_set_size(bdev, config->bytesize);
else
bdev->bd_invalidated = 1;
bdput(bdev);
}
kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
}
static void nbd_size_set(struct nbd_device *nbd, loff_t blocksize,
loff_t nr_blocks)
{
struct nbd_config *config = nbd->config;
config->blksize = blocksize;
config->bytesize = blocksize * nr_blocks;
if (nbd->task_recv != NULL)
nbd_size_update(nbd);
}
static void nbd_complete_rq(struct request *req)
{
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
dev_dbg(nbd_to_dev(cmd->nbd), "request %p: %s\n", req,
cmd->status ? "failed" : "done");
blk_mq_end_request(req, cmd->status);
}
/*
* Forcibly shutdown the socket causing all listeners to error
*/
static void sock_shutdown(struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
int i;
if (config->num_connections == 0)
return;
if (test_and_set_bit(NBD_DISCONNECTED, &config->runtime_flags))
return;
for (i = 0; i < config->num_connections; i++) {
struct nbd_sock *nsock = config->socks[i];
mutex_lock(&nsock->tx_lock);
nbd_mark_nsock_dead(nbd, nsock, 0);
mutex_unlock(&nsock->tx_lock);
}
dev_warn(disk_to_dev(nbd->disk), "shutting down sockets\n");
}
static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
bool reserved)
{
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
struct nbd_device *nbd = cmd->nbd;
struct nbd_config *config;
if (!refcount_inc_not_zero(&nbd->config_refs)) {
cmd->status = BLK_STS_TIMEOUT;
goto done;
}
config = nbd->config;
if (!mutex_trylock(&cmd->lock))
return BLK_EH_RESET_TIMER;
if (config->num_connections > 1) {
dev_err_ratelimited(nbd_to_dev(nbd),
"Connection timed out, retrying (%d/%d alive)\n",
atomic_read(&config->live_connections),
config->num_connections);
/*
* Hooray we have more connections, requeue this IO, the submit
* path will put it on a real connection.
*/
if (config->socks && config->num_connections > 1) {
if (cmd->index < config->num_connections) {
struct nbd_sock *nsock =
config->socks[cmd->index];
mutex_lock(&nsock->tx_lock);
/* We can have multiple outstanding requests, so
* we don't want to mark the nsock dead if we've
* already reconnected with a new socket, so
* only mark it dead if its the same socket we
* were sent out on.
*/
if (cmd->cookie == nsock->cookie)
nbd_mark_nsock_dead(nbd, nsock, 1);
mutex_unlock(&nsock->tx_lock);
}
mutex_unlock(&cmd->lock);
nbd_requeue_cmd(cmd);
nbd_config_put(nbd);
return BLK_EH_DONE;
}
} else {
dev_err_ratelimited(nbd_to_dev(nbd),
"Connection timed out\n");
}
set_bit(NBD_TIMEDOUT, &config->runtime_flags);
cmd->status = BLK_STS_IOERR;
mutex_unlock(&cmd->lock);
sock_shutdown(nbd);
nbd_config_put(nbd);
done:
blk_mq_complete_request(req);
return BLK_EH_DONE;
}
/*
* Send or receive packet.
*/
static int sock_xmit(struct nbd_device *nbd, int index, int send,
struct iov_iter *iter, int msg_flags, int *sent)
{
struct nbd_config *config = nbd->config;
struct socket *sock = config->socks[index]->sock;
int result;
struct msghdr msg;
unsigned int noreclaim_flag;
if (unlikely(!sock)) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Attempted %s on closed socket in sock_xmit\n",
(send ? "send" : "recv"));
return -EINVAL;
}
msg.msg_iter = *iter;
noreclaim_flag = memalloc_noreclaim_save();
do {
sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = msg_flags | MSG_NOSIGNAL;
if (send)
result = sock_sendmsg(sock, &msg);
else
result = sock_recvmsg(sock, &msg, msg.msg_flags);
if (result <= 0) {
if (result == 0)
result = -EPIPE; /* short read */
break;
}
if (sent)
*sent += result;
} while (msg_data_left(&msg));
memalloc_noreclaim_restore(noreclaim_flag);
return result;
}
/*
* Different settings for sk->sk_sndtimeo can result in different return values
* if there is a signal pending when we enter sendmsg, because reasons?
*/
static inline int was_interrupted(int result)
{
return result == -ERESTARTSYS || result == -EINTR;
}
/* always call with the tx_lock held */
static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
{
struct request *req = blk_mq_rq_from_pdu(cmd);
struct nbd_config *config = nbd->config;
struct nbd_sock *nsock = config->socks[index];
int result;
struct nbd_request request = {.magic = htonl(NBD_REQUEST_MAGIC)};
struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
struct iov_iter from;
unsigned long size = blk_rq_bytes(req);
struct bio *bio;
u64 handle;
u32 type;
u32 nbd_cmd_flags = 0;
int sent = nsock->sent, skip = 0;
iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
switch (req_op(req)) {
case REQ_OP_DISCARD:
type = NBD_CMD_TRIM;
break;
case REQ_OP_FLUSH:
type = NBD_CMD_FLUSH;
break;
case REQ_OP_WRITE:
type = NBD_CMD_WRITE;
break;
case REQ_OP_READ:
type = NBD_CMD_READ;
break;
default:
return -EIO;
}
if (rq_data_dir(req) == WRITE &&
(config->flags & NBD_FLAG_READ_ONLY)) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Write on read-only\n");
return -EIO;
}
if (req->cmd_flags & REQ_FUA)
nbd_cmd_flags |= NBD_CMD_FLAG_FUA;
/* We did a partial send previously, and we at least sent the whole
* request struct, so just go and send the rest of the pages in the
* request.
*/
if (sent) {
if (sent >= sizeof(request)) {
skip = sent - sizeof(request);
goto send_pages;
}
iov_iter_advance(&from, sent);
} else {
cmd->cmd_cookie++;
}
cmd->index = index;
cmd->cookie = nsock->cookie;
request.type = htonl(type | nbd_cmd_flags);
if (type != NBD_CMD_FLUSH) {
request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
request.len = htonl(size);
}
handle = nbd_cmd_handle(cmd);
memcpy(request.handle, &handle, sizeof(handle));
dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
req, nbdcmd_to_ascii(type),
(unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
result = sock_xmit(nbd, index, 1, &from,
(type == NBD_CMD_WRITE) ? MSG_MORE : 0, &sent);
if (result <= 0) {
if (was_interrupted(result)) {
/* If we havne't sent anything we can just return BUSY,
* however if we have sent something we need to make
* sure we only allow this req to be sent until we are
* completely done.
*/
if (sent) {
nsock->pending = req;
nsock->sent = sent;
}
set_bit(NBD_CMD_REQUEUED, &cmd->flags);
return BLK_STS_RESOURCE;
}
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Send control failed (result %d)\n", result);
return -EAGAIN;
}
send_pages:
if (type != NBD_CMD_WRITE)
goto out;
bio = req->bio;
while (bio) {
struct bio *next = bio->bi_next;
struct bvec_iter iter;
struct bio_vec bvec;
bio_for_each_segment(bvec, bio, iter) {
bool is_last = !next && bio_iter_last(bvec, iter);
int flags = is_last ? 0 : MSG_MORE;
dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n",
req, bvec.bv_len);
iov_iter_bvec(&from, WRITE, &bvec, 1, bvec.bv_len);
if (skip) {
if (skip >= iov_iter_count(&from)) {
skip -= iov_iter_count(&from);
continue;
}
iov_iter_advance(&from, skip);
skip = 0;
}
result = sock_xmit(nbd, index, 1, &from, flags, &sent);
if (result <= 0) {
if (was_interrupted(result)) {
/* We've already sent the header, we
* have no choice but to set pending and
* return BUSY.
*/
nsock->pending = req;
nsock->sent = sent;
set_bit(NBD_CMD_REQUEUED, &cmd->flags);
return BLK_STS_RESOURCE;
}
dev_err(disk_to_dev(nbd->disk),
"Send data failed (result %d)\n",
result);
return -EAGAIN;
}
/*
* The completion might already have come in,
* so break for the last one instead of letting
* the iterator do it. This prevents use-after-free
* of the bio.
*/
if (is_last)
break;
}
bio = next;
}
out:
nsock->pending = NULL;
nsock->sent = 0;
return 0;
}
/* NULL returned = something went wrong, inform userspace */
static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
{
struct nbd_config *config = nbd->config;
int result;
struct nbd_reply reply;
struct nbd_cmd *cmd;
struct request *req = NULL;
u64 handle;
u16 hwq;
u32 tag;
struct kvec iov = {.iov_base = &reply, .iov_len = sizeof(reply)};
struct iov_iter to;
int ret = 0;
reply.magic = 0;
iov_iter_kvec(&to, READ, &iov, 1, sizeof(reply));
result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
if (result <= 0) {
if (!nbd_disconnected(config))
dev_err(disk_to_dev(nbd->disk),
"Receive control failed (result %d)\n", result);
return ERR_PTR(result);
}
if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
(unsigned long)ntohl(reply.magic));
return ERR_PTR(-EPROTO);
}
memcpy(&handle, reply.handle, sizeof(handle));
tag = nbd_handle_to_tag(handle);
hwq = blk_mq_unique_tag_to_hwq(tag);
if (hwq < nbd->tag_set.nr_hw_queues)
req = blk_mq_tag_to_rq(nbd->tag_set.tags[hwq],
blk_mq_unique_tag_to_tag(tag));
if (!req || !blk_mq_request_started(req)) {
dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%d) %p\n",
tag, req);
return ERR_PTR(-ENOENT);
}
cmd = blk_mq_rq_to_pdu(req);
mutex_lock(&cmd->lock);
if (cmd->cmd_cookie != nbd_handle_to_cookie(handle)) {
dev_err(disk_to_dev(nbd->disk), "Double reply on req %p, cmd_cookie %u, handle cookie %u\n",
req, cmd->cmd_cookie, nbd_handle_to_cookie(handle));
ret = -ENOENT;
goto out;
}
if (test_bit(NBD_CMD_REQUEUED, &cmd->flags)) {
dev_err(disk_to_dev(nbd->disk), "Raced with timeout on req %p\n",
req);
ret = -ENOENT;
goto out;
}
if (ntohl(reply.error)) {
dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
ntohl(reply.error));
cmd->status = BLK_STS_IOERR;
goto out;
}
dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", req);
if (rq_data_dir(req) != WRITE) {
struct req_iterator iter;
struct bio_vec bvec;
rq_for_each_segment(bvec, req, iter) {
iov_iter_bvec(&to, READ, &bvec, 1, bvec.bv_len);
result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
if (result <= 0) {
dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
result);
/*
* If we've disconnected or we only have 1
* connection then we need to make sure we
* complete this request, otherwise error out
* and let the timeout stuff handle resubmitting
* this request onto another connection.
*/
if (nbd_disconnected(config) ||
config->num_connections <= 1) {
cmd->status = BLK_STS_IOERR;
goto out;
}
ret = -EIO;
goto out;
}
dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n",
req, bvec.bv_len);
}
}
out:
mutex_unlock(&cmd->lock);
return ret ? ERR_PTR(ret) : cmd;
}
static void recv_work(struct work_struct *work)
{
struct recv_thread_args *args = container_of(work,
struct recv_thread_args,
work);
struct nbd_device *nbd = args->nbd;
struct nbd_config *config = nbd->config;
struct nbd_cmd *cmd;
while (1) {
cmd = nbd_read_stat(nbd, args->index);
if (IS_ERR(cmd)) {
struct nbd_sock *nsock = config->socks[args->index];
mutex_lock(&nsock->tx_lock);
nbd_mark_nsock_dead(nbd, nsock, 1);
mutex_unlock(&nsock->tx_lock);
break;
}
blk_mq_complete_request(blk_mq_rq_from_pdu(cmd));
}
atomic_dec(&config->recv_threads);
wake_up(&config->recv_wq);
nbd_config_put(nbd);
kfree(args);
}
static void nbd_clear_req(struct request *req, void *data, bool reserved)
{
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
cmd->status = BLK_STS_IOERR;
blk_mq_complete_request(req);
}
static void nbd_clear_que(struct nbd_device *nbd)
{
blk_mq_quiesce_queue(nbd->disk->queue);
blk_mq_tagset_busy_iter(&nbd->tag_set, nbd_clear_req, NULL);
blk_mq_unquiesce_queue(nbd->disk->queue);
dev_dbg(disk_to_dev(nbd->disk), "queue cleared\n");
}
static int find_fallback(struct nbd_device *nbd, int index)
{
struct nbd_config *config = nbd->config;
int new_index = -1;
struct nbd_sock *nsock = config->socks[index];
int fallback = nsock->fallback_index;
if (test_bit(NBD_DISCONNECTED, &config->runtime_flags))
return new_index;
if (config->num_connections <= 1) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Attempted send on invalid socket\n");
return new_index;
}
if (fallback >= 0 && fallback < config->num_connections &&
!config->socks[fallback]->dead)
return fallback;
if (nsock->fallback_index < 0 ||
nsock->fallback_index >= config->num_connections ||
config->socks[nsock->fallback_index]->dead) {
int i;
for (i = 0; i < config->num_connections; i++) {
if (i == index)
continue;
if (!config->socks[i]->dead) {
new_index = i;
break;
}
}
nsock->fallback_index = new_index;
if (new_index < 0) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Dead connection, failed to find a fallback\n");
return new_index;
}
}
new_index = nsock->fallback_index;
return new_index;
}
static int wait_for_reconnect(struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
if (!config->dead_conn_timeout)
return 0;
if (test_bit(NBD_DISCONNECTED, &config->runtime_flags))
return 0;
return wait_event_timeout(config->conn_wait,
atomic_read(&config->live_connections) > 0,
config->dead_conn_timeout) > 0;
}
static int nbd_handle_cmd(struct nbd_cmd *cmd, int index)
{
struct request *req = blk_mq_rq_from_pdu(cmd);
struct nbd_device *nbd = cmd->nbd;
struct nbd_config *config;
struct nbd_sock *nsock;
int ret;
if (!refcount_inc_not_zero(&nbd->config_refs)) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Socks array is empty\n");
blk_mq_start_request(req);
return -EINVAL;
}
config = nbd->config;
if (index >= config->num_connections) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Attempted send on invalid socket\n");
nbd_config_put(nbd);
blk_mq_start_request(req);
return -EINVAL;
}
cmd->status = BLK_STS_OK;
again:
nsock = config->socks[index];
mutex_lock(&nsock->tx_lock);
if (nsock->dead) {
int old_index = index;
index = find_fallback(nbd, index);
mutex_unlock(&nsock->tx_lock);
if (index < 0) {
if (wait_for_reconnect(nbd)) {
index = old_index;
goto again;
}
/* All the sockets should already be down at this point,
* we just want to make sure that DISCONNECTED is set so
* any requests that come in that were queue'ed waiting
* for the reconnect timer don't trigger the timer again
* and instead just error out.
*/
sock_shutdown(nbd);
nbd_config_put(nbd);
blk_mq_start_request(req);
return -EIO;
}
goto again;
}
/* Handle the case that we have a pending request that was partially
* transmitted that _has_ to be serviced first. We need to call requeue
* here so that it gets put _after_ the request that is already on the
* dispatch list.
*/
blk_mq_start_request(req);
if (unlikely(nsock->pending && nsock->pending != req)) {
nbd_requeue_cmd(cmd);
ret = 0;
goto out;
}
/*
* Some failures are related to the link going down, so anything that
* returns EAGAIN can be retried on a different socket.
*/
ret = nbd_send_cmd(nbd, cmd, index);
if (ret == -EAGAIN) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Request send failed, requeueing\n");
nbd_mark_nsock_dead(nbd, nsock, 1);
nbd_requeue_cmd(cmd);
ret = 0;
}
out:
mutex_unlock(&nsock->tx_lock);
nbd_config_put(nbd);
return ret;
}
static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *bd)
{
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
int ret;
/*
* Since we look at the bio's to send the request over the network we
* need to make sure the completion work doesn't mark this request done
* before we are done doing our send. This keeps us from dereferencing
* freed data if we have particularly fast completions (ie we get the
* completion before we exit sock_xmit on the last bvec) or in the case
* that the server is misbehaving (or there was an error) before we're
* done sending everything over the wire.
*/
mutex_lock(&cmd->lock);
clear_bit(NBD_CMD_REQUEUED, &cmd->flags);
/* We can be called directly from the user space process, which means we
* could possibly have signals pending so our sendmsg will fail. In
* this case we need to return that we are busy, otherwise error out as
* appropriate.
*/
ret = nbd_handle_cmd(cmd, hctx->queue_num);
if (ret < 0)
ret = BLK_STS_IOERR;
else if (!ret)
ret = BLK_STS_OK;
mutex_unlock(&cmd->lock);
return ret;
}
static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
bool netlink)
{
struct nbd_config *config = nbd->config;
struct socket *sock;
struct nbd_sock **socks;
struct nbd_sock *nsock;
int err;
sock = sockfd_lookup(arg, &err);
if (!sock)
return err;
if (!netlink && !nbd->task_setup &&
!test_bit(NBD_BOUND, &config->runtime_flags))
nbd->task_setup = current;
if (!netlink &&
(nbd->task_setup != current ||
test_bit(NBD_BOUND, &config->runtime_flags))) {
dev_err(disk_to_dev(nbd->disk),
"Device being setup by another task");
sockfd_put(sock);
return -EBUSY;
}
socks = krealloc(config->socks, (config->num_connections + 1) *
sizeof(struct nbd_sock *), GFP_KERNEL);
if (!socks) {
sockfd_put(sock);
return -ENOMEM;
}
nsock = kzalloc(sizeof(struct nbd_sock), GFP_KERNEL);
if (!nsock) {
sockfd_put(sock);
return -ENOMEM;
}
config->socks = socks;
nsock->fallback_index = -1;
nsock->dead = false;
mutex_init(&nsock->tx_lock);
nsock->sock = sock;
nsock->pending = NULL;
nsock->sent = 0;
nsock->cookie = 0;
socks[config->num_connections++] = nsock;
atomic_inc(&config->live_connections);
return 0;
}
static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
{
struct nbd_config *config = nbd->config;
struct socket *sock, *old;
struct recv_thread_args *args;
int i;
int err;
sock = sockfd_lookup(arg, &err);
if (!sock)
return err;
args = kzalloc(sizeof(*args), GFP_KERNEL);
if (!args) {
sockfd_put(sock);
return -ENOMEM;
}
for (i = 0; i < config->num_connections; i++) {
struct nbd_sock *nsock = config->socks[i];
if (!nsock->dead)
continue;
mutex_lock(&nsock->tx_lock);
if (!nsock->dead) {
mutex_unlock(&nsock->tx_lock);
continue;
}
sk_set_memalloc(sock->sk);
if (nbd->tag_set.timeout)
sock->sk->sk_sndtimeo = nbd->tag_set.timeout;
atomic_inc(&config->recv_threads);
refcount_inc(&nbd->config_refs);
old = nsock->sock;
nsock->fallback_index = -1;
nsock->sock = sock;
nsock->dead = false;
INIT_WORK(&args->work, recv_work);
args->index = i;
args->nbd = nbd;
nsock->cookie++;
mutex_unlock(&nsock->tx_lock);
sockfd_put(old);
clear_bit(NBD_DISCONNECTED, &config->runtime_flags);
/* We take the tx_mutex in an error path in the recv_work, so we
* need to queue_work outside of the tx_mutex.
*/
queue_work(recv_workqueue, &args->work);
atomic_inc(&config->live_connections);
wake_up(&config->conn_wait);
return 0;
}
sockfd_put(sock);
kfree(args);
return -ENOSPC;
}
static void nbd_bdev_reset(struct block_device *bdev)
{
if (bdev->bd_openers > 1)
return;
bd_set_size(bdev, 0);
}
static void nbd_parse_flags(struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
if (config->flags & NBD_FLAG_READ_ONLY)
set_disk_ro(nbd->disk, true);
else
set_disk_ro(nbd->disk, false);
if (config->flags & NBD_FLAG_SEND_TRIM)
blk_queue_flag_set(QUEUE_FLAG_DISCARD, nbd->disk->queue);
if (config->flags & NBD_FLAG_SEND_FLUSH) {
if (config->flags & NBD_FLAG_SEND_FUA)
blk_queue_write_cache(nbd->disk->queue, true, true);
else
blk_queue_write_cache(nbd->disk->queue, true, false);
}
else
blk_queue_write_cache(nbd->disk->queue, false, false);
}
static void send_disconnects(struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
struct nbd_request request = {
.magic = htonl(NBD_REQUEST_MAGIC),
.type = htonl(NBD_CMD_DISC),
};
struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
struct iov_iter from;
int i, ret;
for (i = 0; i < config->num_connections; i++) {
struct nbd_sock *nsock = config->socks[i];
iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
mutex_lock(&nsock->tx_lock);
ret = sock_xmit(nbd, i, 1, &from, 0, NULL);
if (ret <= 0)
dev_err(disk_to_dev(nbd->disk),
"Send disconnect failed %d\n", ret);
mutex_unlock(&nsock->tx_lock);
}
}
static int nbd_disconnect(struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
set_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags);
send_disconnects(nbd);
return 0;
}
static void nbd_clear_sock(struct nbd_device *nbd)
{
sock_shutdown(nbd);
nbd_clear_que(nbd);
nbd->task_setup = NULL;
}
static void nbd_config_put(struct nbd_device *nbd)
{
if (refcount_dec_and_mutex_lock(&nbd->config_refs,
&nbd->config_lock)) {
struct nbd_config *config = nbd->config;
nbd_dev_dbg_close(nbd);
nbd_size_clear(nbd);
if (test_and_clear_bit(NBD_HAS_PID_FILE,
&config->runtime_flags))
device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
nbd->task_recv = NULL;
nbd_clear_sock(nbd);
if (config->num_connections) {
int i;
for (i = 0; i < config->num_connections; i++) {
sockfd_put(config->socks[i]->sock);
kfree(config->socks[i]);
}
kfree(config->socks);
}
kfree(nbd->config);
nbd->config = NULL;
nbd->tag_set.timeout = 0;
nbd->disk->queue->limits.discard_granularity = 0;
nbd->disk->queue->limits.discard_alignment = 0;
blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
blk_queue_flag_clear(QUEUE_FLAG_DISCARD, nbd->disk->queue);
mutex_unlock(&nbd->config_lock);
nbd_put(nbd);
module_put(THIS_MODULE);
}
}
static int nbd_start_device(struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
int num_connections = config->num_connections;
int error = 0, i;
if (nbd->task_recv)
return -EBUSY;
if (!config->socks)
return -EINVAL;
if (num_connections > 1 &&
!(config->flags & NBD_FLAG_CAN_MULTI_CONN)) {
dev_err(disk_to_dev(nbd->disk), "server does not support multiple connections per device.\n");
return -EINVAL;
}
blk_mq_update_nr_hw_queues(&nbd->tag_set, config->num_connections);
nbd->task_recv = current;
nbd_parse_flags(nbd);
error = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
if (error) {
dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
return error;
}
set_bit(NBD_HAS_PID_FILE, &config->runtime_flags);
nbd_dev_dbg_init(nbd);
for (i = 0; i < num_connections; i++) {
struct recv_thread_args *args;
args = kzalloc(sizeof(*args), GFP_KERNEL);
if (!args) {
sock_shutdown(nbd);
return -ENOMEM;
}
sk_set_memalloc(config->socks[i]->sock->sk);
if (nbd->tag_set.timeout)
config->socks[i]->sock->sk->sk_sndtimeo =
nbd->tag_set.timeout;
atomic_inc(&config->recv_threads);
refcount_inc(&nbd->config_refs);
INIT_WORK(&args->work, recv_work);
args->nbd = nbd;
args->index = i;
queue_work(recv_workqueue, &args->work);
}
nbd_size_update(nbd);
return error;
}
static int nbd_start_device_ioctl(struct nbd_device *nbd, struct block_device *bdev)
{
struct nbd_config *config = nbd->config;
int ret;
ret = nbd_start_device(nbd);
if (ret)
return ret;
if (max_part)
bdev->bd_invalidated = 1;
mutex_unlock(&nbd->config_lock);
ret = wait_event_interruptible(config->recv_wq,
atomic_read(&config->recv_threads) == 0);
if (ret)
sock_shutdown(nbd);
mutex_lock(&nbd->config_lock);
nbd_bdev_reset(bdev);
/* user requested, ignore socket errors */
if (test_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags))
ret = 0;
if (test_bit(NBD_TIMEDOUT, &config->runtime_flags))
ret = -ETIMEDOUT;
return ret;
}
static void nbd_clear_sock_ioctl(struct nbd_device *nbd,
struct block_device *bdev)
{
sock_shutdown(nbd);
kill_bdev(bdev);
nbd_bdev_reset(bdev);
if (test_and_clear_bit(NBD_HAS_CONFIG_REF,
&nbd->config->runtime_flags))
nbd_config_put(nbd);
}
/* Must be called with config_lock held */
static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
unsigned int cmd, unsigned long arg)
{
struct nbd_config *config = nbd->config;
switch (cmd) {
case NBD_DISCONNECT:
return nbd_disconnect(nbd);
case NBD_CLEAR_SOCK:
nbd_clear_sock_ioctl(nbd, bdev);
return 0;
case NBD_SET_SOCK:
return nbd_add_socket(nbd, arg, false);
case NBD_SET_BLKSIZE:
if (!arg || !is_power_of_2(arg) || arg < 512 ||
arg > PAGE_SIZE)
return -EINVAL;
nbd_size_set(nbd, arg,
div_s64(config->bytesize, arg));
return 0;
case NBD_SET_SIZE:
nbd_size_set(nbd, config->blksize,
div_s64(arg, config->blksize));
return 0;
case NBD_SET_SIZE_BLOCKS:
nbd_size_set(nbd, config->blksize, arg);
return 0;
case NBD_SET_TIMEOUT:
if (arg) {
nbd->tag_set.timeout = arg * HZ;
blk_queue_rq_timeout(nbd->disk->queue, arg * HZ);
}
return 0;
case NBD_SET_FLAGS:
config->flags = arg;
return 0;
case NBD_DO_IT:
return nbd_start_device_ioctl(nbd, bdev);
case NBD_CLEAR_QUE:
/*
* This is for compatibility only. The queue is always cleared
* by NBD_DO_IT or NBD_CLEAR_SOCK.
*/
return 0;
case NBD_PRINT_DEBUG:
/*
* For compatibility only, we no longer keep a list of
* outstanding requests.
*/
return 0;
}
return -ENOTTY;
}
static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
unsigned int cmd, unsigned long arg)
{
struct nbd_device *nbd = bdev->bd_disk->private_data;
struct nbd_config *config = nbd->config;
int error = -EINVAL;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
/* The block layer will pass back some non-nbd ioctls in case we have
* special handling for them, but we don't so just return an error.
*/
if (_IOC_TYPE(cmd) != 0xab)
return -EINVAL;
mutex_lock(&nbd->config_lock);
/* Don't allow ioctl operations on a nbd device that was created with
* netlink, unless it's DISCONNECT or CLEAR_SOCK, which are fine.
*/
if (!test_bit(NBD_BOUND, &config->runtime_flags) ||
(cmd == NBD_DISCONNECT || cmd == NBD_CLEAR_SOCK))
error = __nbd_ioctl(bdev, nbd, cmd, arg);
else
dev_err(nbd_to_dev(nbd), "Cannot use ioctl interface on a netlink controlled device.\n");
mutex_unlock(&nbd->config_lock);
return error;
}
static struct nbd_config *nbd_alloc_config(void)
{
struct nbd_config *config;
config = kzalloc(sizeof(struct nbd_config), GFP_NOFS);
if (!config)
return NULL;
atomic_set(&config->recv_threads, 0);
init_waitqueue_head(&config->recv_wq);
init_waitqueue_head(&config->conn_wait);
config->blksize = 1024;
atomic_set(&config->live_connections, 0);
try_module_get(THIS_MODULE);
return config;
}
static int nbd_open(struct block_device *bdev, fmode_t mode)
{
struct nbd_device *nbd;
int ret = 0;
mutex_lock(&nbd_index_mutex);
nbd = bdev->bd_disk->private_data;
if (!nbd) {
ret = -ENXIO;
goto out;
}
if (!refcount_inc_not_zero(&nbd->refs)) {
ret = -ENXIO;
goto out;
}
if (!refcount_inc_not_zero(&nbd->config_refs)) {
struct nbd_config *config;
mutex_lock(&nbd->config_lock);
if (refcount_inc_not_zero(&nbd->config_refs)) {
mutex_unlock(&nbd->config_lock);
goto out;
}
config = nbd->config = nbd_alloc_config();
if (!config) {
ret = -ENOMEM;
mutex_unlock(&nbd->config_lock);
goto out;
}
refcount_set(&nbd->config_refs, 1);
refcount_inc(&nbd->refs);
mutex_unlock(&nbd->config_lock);
bdev->bd_invalidated = 1;
} else if (nbd_disconnected(nbd->config)) {
bdev->bd_invalidated = 1;
}
out:
mutex_unlock(&nbd_index_mutex);
return ret;
}
static void nbd_release(struct gendisk *disk, fmode_t mode)
{
struct nbd_device *nbd = disk->private_data;
struct block_device *bdev = bdget_disk(disk, 0);
if (test_bit(NBD_DISCONNECT_ON_CLOSE, &nbd->config->runtime_flags) &&
bdev->bd_openers == 0)
nbd_disconnect_and_put(nbd);
nbd_config_put(nbd);
nbd_put(nbd);
}
static const struct block_device_operations nbd_fops =
{
.owner = THIS_MODULE,
.open = nbd_open,
.release = nbd_release,
.ioctl = nbd_ioctl,
.compat_ioctl = nbd_ioctl,
};
#if IS_ENABLED(CONFIG_DEBUG_FS)
static int nbd_dbg_tasks_show(struct seq_file *s, void *unused)
{
struct nbd_device *nbd = s->private;
if (nbd->task_recv)
seq_printf(s, "recv: %d\n", task_pid_nr(nbd->task_recv));
return 0;
}
static int nbd_dbg_tasks_open(struct inode *inode, struct file *file)
{
return single_open(file, nbd_dbg_tasks_show, inode->i_private);
}
static const struct file_operations nbd_dbg_tasks_ops = {
.open = nbd_dbg_tasks_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int nbd_dbg_flags_show(struct seq_file *s, void *unused)
{
struct nbd_device *nbd = s->private;
u32 flags = nbd->config->flags;
seq_printf(s, "Hex: 0x%08x\n\n", flags);
seq_puts(s, "Known flags:\n");
if (flags & NBD_FLAG_HAS_FLAGS)
seq_puts(s, "NBD_FLAG_HAS_FLAGS\n");
if (flags & NBD_FLAG_READ_ONLY)
seq_puts(s, "NBD_FLAG_READ_ONLY\n");
if (flags & NBD_FLAG_SEND_FLUSH)
seq_puts(s, "NBD_FLAG_SEND_FLUSH\n");
if (flags & NBD_FLAG_SEND_FUA)
seq_puts(s, "NBD_FLAG_SEND_FUA\n");
if (flags & NBD_FLAG_SEND_TRIM)
seq_puts(s, "NBD_FLAG_SEND_TRIM\n");
return 0;
}
static int nbd_dbg_flags_open(struct inode *inode, struct file *file)
{
return single_open(file, nbd_dbg_flags_show, inode->i_private);
}
static const struct file_operations nbd_dbg_flags_ops = {
.open = nbd_dbg_flags_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int nbd_dev_dbg_init(struct nbd_device *nbd)
{
struct dentry *dir;
struct nbd_config *config = nbd->config;
if (!nbd_dbg_dir)
return -EIO;
dir = debugfs_create_dir(nbd_name(nbd), nbd_dbg_dir);
if (!dir) {
dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for '%s'\n",
nbd_name(nbd));
return -EIO;
}
config->dbg_dir = dir;
debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_ops);
debugfs_create_u64("size_bytes", 0444, dir, &config->bytesize);
debugfs_create_u32("timeout", 0444, dir, &nbd->tag_set.timeout);
debugfs_create_u64("blocksize", 0444, dir, &config->blksize);
debugfs_create_file("flags", 0444, dir, nbd, &nbd_dbg_flags_ops);
return 0;
}
static void nbd_dev_dbg_close(struct nbd_device *nbd)
{
debugfs_remove_recursive(nbd->config->dbg_dir);
}
static int nbd_dbg_init(void)
{
struct dentry *dbg_dir;
dbg_dir = debugfs_create_dir("nbd", NULL);
if (!dbg_dir)
return -EIO;
nbd_dbg_dir = dbg_dir;
return 0;
}
static void nbd_dbg_close(void)
{
debugfs_remove_recursive(nbd_dbg_dir);
}
#else /* IS_ENABLED(CONFIG_DEBUG_FS) */
static int nbd_dev_dbg_init(struct nbd_device *nbd)
{
return 0;
}
static void nbd_dev_dbg_close(struct nbd_device *nbd)
{
}
static int nbd_dbg_init(void)
{
return 0;
}
static void nbd_dbg_close(void)
{
}
#endif
static int nbd_init_request(struct blk_mq_tag_set *set, struct request *rq,
unsigned int hctx_idx, unsigned int numa_node)
{
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq);
cmd->nbd = set->driver_data;
cmd->flags = 0;
mutex_init(&cmd->lock);
return 0;
}
static const struct blk_mq_ops nbd_mq_ops = {
.queue_rq = nbd_queue_rq,
.complete = nbd_complete_rq,
.init_request = nbd_init_request,
.timeout = nbd_xmit_timeout,
};
static int nbd_dev_add(int index)
{
struct nbd_device *nbd;
struct gendisk *disk;
struct request_queue *q;
int err = -ENOMEM;
nbd = kzalloc(sizeof(struct nbd_device), GFP_KERNEL);
if (!nbd)
goto out;
disk = alloc_disk(1 << part_shift);
if (!disk)
goto out_free_nbd;
if (index >= 0) {
err = idr_alloc(&nbd_index_idr, nbd, index, index + 1,
GFP_KERNEL);
if (err == -ENOSPC)
err = -EEXIST;
} else {
err = idr_alloc(&nbd_index_idr, nbd, 0, 0, GFP_KERNEL);
if (err >= 0)
index = err;
}
if (err < 0)
goto out_free_disk;
nbd->index = index;
nbd->disk = disk;
nbd->tag_set.ops = &nbd_mq_ops;
nbd->tag_set.nr_hw_queues = 1;
nbd->tag_set.queue_depth = 128;
nbd->tag_set.numa_node = NUMA_NO_NODE;
nbd->tag_set.cmd_size = sizeof(struct nbd_cmd);
nbd->tag_set.flags = BLK_MQ_F_SHOULD_MERGE |
BLK_MQ_F_SG_MERGE | BLK_MQ_F_BLOCKING;
nbd->tag_set.driver_data = nbd;
err = blk_mq_alloc_tag_set(&nbd->tag_set);
if (err)
goto out_free_idr;
q = blk_mq_init_queue(&nbd->tag_set);
if (IS_ERR(q)) {
err = PTR_ERR(q);
goto out_free_tags;
}
disk->queue = q;
/*
* Tell the block layer that we are not a rotational device
*/
blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, disk->queue);
disk->queue->limits.discard_granularity = 0;
disk->queue->limits.discard_alignment = 0;
blk_queue_max_discard_sectors(disk->queue, 0);
blk_queue_max_segment_size(disk->queue, UINT_MAX);
blk_queue_max_segments(disk->queue, USHRT_MAX);
blk_queue_max_hw_sectors(disk->queue, 65536);
disk->queue->limits.max_sectors = 256;
mutex_init(&nbd->config_lock);
refcount_set(&nbd->config_refs, 0);
refcount_set(&nbd->refs, 1);
INIT_LIST_HEAD(&nbd->list);
disk->major = NBD_MAJOR;
disk->first_minor = index << part_shift;
disk->fops = &nbd_fops;
disk->private_data = nbd;
sprintf(disk->disk_name, "nbd%d", index);
add_disk(disk);
nbd_total_devices++;
return index;
out_free_tags:
blk_mq_free_tag_set(&nbd->tag_set);
out_free_idr:
idr_remove(&nbd_index_idr, index);
out_free_disk:
put_disk(disk);
out_free_nbd:
kfree(nbd);
out:
return err;
}
static int find_free_cb(int id, void *ptr, void *data)
{
struct nbd_device *nbd = ptr;
struct nbd_device **found = data;
if (!refcount_read(&nbd->config_refs)) {
*found = nbd;
return 1;
}
return 0;
}
/* Netlink interface. */
static const struct nla_policy nbd_attr_policy[NBD_ATTR_MAX + 1] = {
[NBD_ATTR_INDEX] = { .type = NLA_U32 },
[NBD_ATTR_SIZE_BYTES] = { .type = NLA_U64 },
[NBD_ATTR_BLOCK_SIZE_BYTES] = { .type = NLA_U64 },
[NBD_ATTR_TIMEOUT] = { .type = NLA_U64 },
[NBD_ATTR_SERVER_FLAGS] = { .type = NLA_U64 },
[NBD_ATTR_CLIENT_FLAGS] = { .type = NLA_U64 },
[NBD_ATTR_SOCKETS] = { .type = NLA_NESTED},
[NBD_ATTR_DEAD_CONN_TIMEOUT] = { .type = NLA_U64 },
[NBD_ATTR_DEVICE_LIST] = { .type = NLA_NESTED},
};
static const struct nla_policy nbd_sock_policy[NBD_SOCK_MAX + 1] = {
[NBD_SOCK_FD] = { .type = NLA_U32 },
};
/* We don't use this right now since we don't parse the incoming list, but we
* still want it here so userspace knows what to expect.
*/
static const struct nla_policy __attribute__((unused))
nbd_device_policy[NBD_DEVICE_ATTR_MAX + 1] = {
[NBD_DEVICE_INDEX] = { .type = NLA_U32 },
[NBD_DEVICE_CONNECTED] = { .type = NLA_U8 },
};
static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
{
struct nbd_device *nbd = NULL;
struct nbd_config *config;
int index = -1;
int ret;
bool put_dev = false;
if (!netlink_capable(skb, CAP_SYS_ADMIN))
return -EPERM;
if (info->attrs[NBD_ATTR_INDEX])
index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
if (!info->attrs[NBD_ATTR_SOCKETS]) {
printk(KERN_ERR "nbd: must specify at least one socket\n");
return -EINVAL;
}
if (!info->attrs[NBD_ATTR_SIZE_BYTES]) {
printk(KERN_ERR "nbd: must specify a size in bytes for the device\n");
return -EINVAL;
}
again:
mutex_lock(&nbd_index_mutex);
if (index == -1) {
ret = idr_for_each(&nbd_index_idr, &find_free_cb, &nbd);
if (ret == 0) {
int new_index;
new_index = nbd_dev_add(-1);
if (new_index < 0) {
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: failed to add new device\n");
return new_index;
}
nbd = idr_find(&nbd_index_idr, new_index);
}
} else {
nbd = idr_find(&nbd_index_idr, index);
if (!nbd) {
ret = nbd_dev_add(index);
if (ret < 0) {
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: failed to add new device\n");
return ret;
}
nbd = idr_find(&nbd_index_idr, index);
}
}
if (!nbd) {
printk(KERN_ERR "nbd: couldn't find device at index %d\n",
index);
mutex_unlock(&nbd_index_mutex);
return -EINVAL;
}
if (!refcount_inc_not_zero(&nbd->refs)) {
mutex_unlock(&nbd_index_mutex);
if (index == -1)
goto again;
printk(KERN_ERR "nbd: device at index %d is going down\n",
index);
return -EINVAL;
}
mutex_unlock(&nbd_index_mutex);
mutex_lock(&nbd->config_lock);
if (refcount_read(&nbd->config_refs)) {
mutex_unlock(&nbd->config_lock);
nbd_put(nbd);
if (index == -1)
goto again;
printk(KERN_ERR "nbd: nbd%d already in use\n", index);
return -EBUSY;
}
if (WARN_ON(nbd->config)) {
mutex_unlock(&nbd->config_lock);
nbd_put(nbd);
return -EINVAL;
}
config = nbd->config = nbd_alloc_config();
if (!nbd->config) {
mutex_unlock(&nbd->config_lock);
nbd_put(nbd);
printk(KERN_ERR "nbd: couldn't allocate config\n");
return -ENOMEM;
}
refcount_set(&nbd->config_refs, 1);
set_bit(NBD_BOUND, &config->runtime_flags);
if (info->attrs[NBD_ATTR_SIZE_BYTES]) {
u64 bytes = nla_get_u64(info->attrs[NBD_ATTR_SIZE_BYTES]);
nbd_size_set(nbd, config->blksize,
div64_u64(bytes, config->blksize));
}
if (info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]) {
u64 bsize =
nla_get_u64(info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]);
nbd_size_set(nbd, bsize, div64_u64(config->bytesize, bsize));
}
if (info->attrs[NBD_ATTR_TIMEOUT]) {
u64 timeout = nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]);
nbd->tag_set.timeout = timeout * HZ;
blk_queue_rq_timeout(nbd->disk->queue, timeout * HZ);
}
if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
config->dead_conn_timeout =
nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
config->dead_conn_timeout *= HZ;
}
if (info->attrs[NBD_ATTR_SERVER_FLAGS])
config->flags =
nla_get_u64(info->attrs[NBD_ATTR_SERVER_FLAGS]);
if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);
if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
set_bit(NBD_DESTROY_ON_DISCONNECT,
&config->runtime_flags);
put_dev = true;
}
if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
set_bit(NBD_DISCONNECT_ON_CLOSE,
&config->runtime_flags);
}
}
if (info->attrs[NBD_ATTR_SOCKETS]) {
struct nlattr *attr;
int rem, fd;
nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
rem) {
struct nlattr *socks[NBD_SOCK_MAX+1];
if (nla_type(attr) != NBD_SOCK_ITEM) {
printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
ret = -EINVAL;
goto out;
}
ret = nla_parse_nested(socks, NBD_SOCK_MAX, attr,
nbd_sock_policy, info->extack);
if (ret != 0) {
printk(KERN_ERR "nbd: error processing sock list\n");
ret = -EINVAL;
goto out;
}
if (!socks[NBD_SOCK_FD])
continue;
fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
ret = nbd_add_socket(nbd, fd, true);
if (ret)
goto out;
}
}
ret = nbd_start_device(nbd);
out:
mutex_unlock(&nbd->config_lock);
if (!ret) {
set_bit(NBD_HAS_CONFIG_REF, &config->runtime_flags);
refcount_inc(&nbd->config_refs);
nbd_connect_reply(info, nbd->index);
}
nbd_config_put(nbd);
if (put_dev)
nbd_put(nbd);
return ret;
}
static void nbd_disconnect_and_put(struct nbd_device *nbd)
{
mutex_lock(&nbd->config_lock);
nbd_disconnect(nbd);
nbd_clear_sock(nbd);
mutex_unlock(&nbd->config_lock);
if (test_and_clear_bit(NBD_HAS_CONFIG_REF,
&nbd->config->runtime_flags))
nbd_config_put(nbd);
}
static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
{
struct nbd_device *nbd;
int index;
if (!netlink_capable(skb, CAP_SYS_ADMIN))
return -EPERM;
if (!info->attrs[NBD_ATTR_INDEX]) {
printk(KERN_ERR "nbd: must specify an index to disconnect\n");
return -EINVAL;
}
index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
mutex_lock(&nbd_index_mutex);
nbd = idr_find(&nbd_index_idr, index);
if (!nbd) {
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: couldn't find device at index %d\n",
index);
return -EINVAL;
}
if (!refcount_inc_not_zero(&nbd->refs)) {
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: device at index %d is going down\n",
index);
return -EINVAL;
}
mutex_unlock(&nbd_index_mutex);
if (!refcount_inc_not_zero(&nbd->config_refs)) {
nbd_put(nbd);
return 0;
}
nbd_disconnect_and_put(nbd);
nbd_config_put(nbd);
nbd_put(nbd);
return 0;
}
static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
{
struct nbd_device *nbd = NULL;
struct nbd_config *config;
int index;
int ret = 0;
bool put_dev = false;
if (!netlink_capable(skb, CAP_SYS_ADMIN))
return -EPERM;
if (!info->attrs[NBD_ATTR_INDEX]) {
printk(KERN_ERR "nbd: must specify a device to reconfigure\n");
return -EINVAL;
}
index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
mutex_lock(&nbd_index_mutex);
nbd = idr_find(&nbd_index_idr, index);
if (!nbd) {
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: couldn't find a device at index %d\n",
index);
return -EINVAL;
}
if (!refcount_inc_not_zero(&nbd->refs)) {
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: device at index %d is going down\n",
index);
return -EINVAL;
}
mutex_unlock(&nbd_index_mutex);
if (!refcount_inc_not_zero(&nbd->config_refs)) {
dev_err(nbd_to_dev(nbd),
"not configured, cannot reconfigure\n");
nbd_put(nbd);
return -EINVAL;
}
mutex_lock(&nbd->config_lock);
config = nbd->config;
if (!test_bit(NBD_BOUND, &config->runtime_flags) ||
!nbd->task_recv) {
dev_err(nbd_to_dev(nbd),
"not configured, cannot reconfigure\n");
ret = -EINVAL;
goto out;
}
if (info->attrs[NBD_ATTR_TIMEOUT]) {
u64 timeout = nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]);
nbd->tag_set.timeout = timeout * HZ;
blk_queue_rq_timeout(nbd->disk->queue, timeout * HZ);
}
if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
config->dead_conn_timeout =
nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
config->dead_conn_timeout *= HZ;
}
if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);
if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
if (!test_and_set_bit(NBD_DESTROY_ON_DISCONNECT,
&config->runtime_flags))
put_dev = true;
} else {
if (test_and_clear_bit(NBD_DESTROY_ON_DISCONNECT,
&config->runtime_flags))
refcount_inc(&nbd->refs);
}
if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
set_bit(NBD_DISCONNECT_ON_CLOSE,
&config->runtime_flags);
} else {
clear_bit(NBD_DISCONNECT_ON_CLOSE,
&config->runtime_flags);
}
}
if (info->attrs[NBD_ATTR_SOCKETS]) {
struct nlattr *attr;
int rem, fd;
nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
rem) {
struct nlattr *socks[NBD_SOCK_MAX+1];
if (nla_type(attr) != NBD_SOCK_ITEM) {
printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
ret = -EINVAL;
goto out;
}
ret = nla_parse_nested(socks, NBD_SOCK_MAX, attr,
nbd_sock_policy, info->extack);
if (ret != 0) {
printk(KERN_ERR "nbd: error processing sock list\n");
ret = -EINVAL;
goto out;
}
if (!socks[NBD_SOCK_FD])
continue;
fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
ret = nbd_reconnect_socket(nbd, fd);
if (ret) {
if (ret == -ENOSPC)
ret = 0;
goto out;
}
dev_info(nbd_to_dev(nbd), "reconnected socket\n");
}
}
out:
mutex_unlock(&nbd->config_lock);
nbd_config_put(nbd);
nbd_put(nbd);
if (put_dev)
nbd_put(nbd);
return ret;
}
static const struct genl_ops nbd_connect_genl_ops[] = {
{
.cmd = NBD_CMD_CONNECT,
.policy = nbd_attr_policy,
.doit = nbd_genl_connect,
},
{
.cmd = NBD_CMD_DISCONNECT,
.policy = nbd_attr_policy,
.doit = nbd_genl_disconnect,
},
{
.cmd = NBD_CMD_RECONFIGURE,
.policy = nbd_attr_policy,
.doit = nbd_genl_reconfigure,
},
{
.cmd = NBD_CMD_STATUS,
.policy = nbd_attr_policy,
.doit = nbd_genl_status,
},
};
static const struct genl_multicast_group nbd_mcast_grps[] = {
{ .name = NBD_GENL_MCAST_GROUP_NAME, },
};
static struct genl_family nbd_genl_family __ro_after_init = {
.hdrsize = 0,
.name = NBD_GENL_FAMILY_NAME,
.version = NBD_GENL_VERSION,
.module = THIS_MODULE,
.ops = nbd_connect_genl_ops,
.n_ops = ARRAY_SIZE(nbd_connect_genl_ops),
.maxattr = NBD_ATTR_MAX,
.mcgrps = nbd_mcast_grps,
.n_mcgrps = ARRAY_SIZE(nbd_mcast_grps),
};
static int populate_nbd_status(struct nbd_device *nbd, struct sk_buff *reply)
{
struct nlattr *dev_opt;
u8 connected = 0;
int ret;
/* This is a little racey, but for status it's ok. The
* reason we don't take a ref here is because we can't
* take a ref in the index == -1 case as we would need
* to put under the nbd_index_mutex, which could
* deadlock if we are configured to remove ourselves
* once we're disconnected.
*/
if (refcount_read(&nbd->config_refs))
connected = 1;
dev_opt = nla_nest_start(reply, NBD_DEVICE_ITEM);
if (!dev_opt)
return -EMSGSIZE;
ret = nla_put_u32(reply, NBD_DEVICE_INDEX, nbd->index);
if (ret)
return -EMSGSIZE;
ret = nla_put_u8(reply, NBD_DEVICE_CONNECTED,
connected);
if (ret)
return -EMSGSIZE;
nla_nest_end(reply, dev_opt);
return 0;
}
static int status_cb(int id, void *ptr, void *data)
{
struct nbd_device *nbd = ptr;
return populate_nbd_status(nbd, (struct sk_buff *)data);
}
static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info)
{
struct nlattr *dev_list;
struct sk_buff *reply;
void *reply_head;
size_t msg_size;
int index = -1;
int ret = -ENOMEM;
if (info->attrs[NBD_ATTR_INDEX])
index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
mutex_lock(&nbd_index_mutex);
msg_size = nla_total_size(nla_attr_size(sizeof(u32)) +
nla_attr_size(sizeof(u8)));
msg_size *= (index == -1) ? nbd_total_devices : 1;
reply = genlmsg_new(msg_size, GFP_KERNEL);
if (!reply)
goto out;
reply_head = genlmsg_put_reply(reply, info, &nbd_genl_family, 0,
NBD_CMD_STATUS);
if (!reply_head) {
nlmsg_free(reply);
goto out;
}
dev_list = nla_nest_start(reply, NBD_ATTR_DEVICE_LIST);
if (index == -1) {
ret = idr_for_each(&nbd_index_idr, &status_cb, reply);
if (ret) {
nlmsg_free(reply);
goto out;
}
} else {
struct nbd_device *nbd;
nbd = idr_find(&nbd_index_idr, index);
if (nbd) {
ret = populate_nbd_status(nbd, reply);
if (ret) {
nlmsg_free(reply);
goto out;
}
}
}
nla_nest_end(reply, dev_list);
genlmsg_end(reply, reply_head);
genlmsg_reply(reply, info);
ret = 0;
out:
mutex_unlock(&nbd_index_mutex);
return ret;
}
static void nbd_connect_reply(struct genl_info *info, int index)
{
struct sk_buff *skb;
void *msg_head;
int ret;
skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
if (!skb)
return;
msg_head = genlmsg_put_reply(skb, info, &nbd_genl_family, 0,
NBD_CMD_CONNECT);
if (!msg_head) {
nlmsg_free(skb);
return;
}
ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
if (ret) {
nlmsg_free(skb);
return;
}
genlmsg_end(skb, msg_head);
genlmsg_reply(skb, info);
}
static void nbd_mcast_index(int index)
{
struct sk_buff *skb;
void *msg_head;
int ret;
skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
if (!skb)
return;
msg_head = genlmsg_put(skb, 0, 0, &nbd_genl_family, 0,
NBD_CMD_LINK_DEAD);
if (!msg_head) {
nlmsg_free(skb);
return;
}
ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
if (ret) {
nlmsg_free(skb);
return;
}
genlmsg_end(skb, msg_head);
genlmsg_multicast(&nbd_genl_family, skb, 0, 0, GFP_KERNEL);
}
static void nbd_dead_link_work(struct work_struct *work)
{
struct link_dead_args *args = container_of(work, struct link_dead_args,
work);
nbd_mcast_index(args->index);
kfree(args);
}
static int __init nbd_init(void)
{
int i;
BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
if (max_part < 0) {
printk(KERN_ERR "nbd: max_part must be >= 0\n");
return -EINVAL;
}
part_shift = 0;
if (max_part > 0) {
part_shift = fls(max_part);
/*
* Adjust max_part according to part_shift as it is exported
* to user space so that user can know the max number of
* partition kernel should be able to manage.
*
* Note that -1 is required because partition 0 is reserved
* for the whole disk.
*/
max_part = (1UL << part_shift) - 1;
}
if ((1UL << part_shift) > DISK_MAX_PARTS)
return -EINVAL;
if (nbds_max > 1UL << (MINORBITS - part_shift))
return -EINVAL;
recv_workqueue = alloc_workqueue("knbd-recv",
WQ_MEM_RECLAIM | WQ_HIGHPRI |
WQ_UNBOUND, 0);
if (!recv_workqueue)
return -ENOMEM;
if (register_blkdev(NBD_MAJOR, "nbd")) {
destroy_workqueue(recv_workqueue);
return -EIO;
}
if (genl_register_family(&nbd_genl_family)) {
unregister_blkdev(NBD_MAJOR, "nbd");
destroy_workqueue(recv_workqueue);
return -EINVAL;
}
nbd_dbg_init();
mutex_lock(&nbd_index_mutex);
for (i = 0; i < nbds_max; i++)
nbd_dev_add(i);
mutex_unlock(&nbd_index_mutex);
return 0;
}
static int nbd_exit_cb(int id, void *ptr, void *data)
{
struct list_head *list = (struct list_head *)data;
struct nbd_device *nbd = ptr;
list_add_tail(&nbd->list, list);
return 0;
}
static void __exit nbd_cleanup(void)
{
struct nbd_device *nbd;
LIST_HEAD(del_list);
nbd_dbg_close();
mutex_lock(&nbd_index_mutex);
idr_for_each(&nbd_index_idr, &nbd_exit_cb, &del_list);
mutex_unlock(&nbd_index_mutex);
while (!list_empty(&del_list)) {
nbd = list_first_entry(&del_list, struct nbd_device, list);
list_del_init(&nbd->list);
if (refcount_read(&nbd->refs) != 1)
printk(KERN_ERR "nbd: possibly leaking a device\n");
nbd_put(nbd);
}
idr_destroy(&nbd_index_idr);
genl_unregister_family(&nbd_genl_family);
destroy_workqueue(recv_workqueue);
unregister_blkdev(NBD_MAJOR, "nbd");
}
module_init(nbd_init);
module_exit(nbd_cleanup);
MODULE_DESCRIPTION("Network Block Device");
MODULE_LICENSE("GPL");
module_param(nbds_max, int, 0444);
MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
module_param(max_part, int, 0444);
MODULE_PARM_DESC(max_part, "number of partitions per device (default: 16)");
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