linux/fs/cachefiles/ondemand.c
Jeffle Xu 1519670e4f cachefiles: add tracepoints for on-demand read mode
Add tracepoints for on-demand read mode. Currently following tracepoints
are added:

	OPEN request / COPEN reply
	CLOSE request
	READ request / CREAD reply
	write through anonymous fd
	release of anonymous fd

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Acked-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20220425122143.56815-8-jefflexu@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2022-05-18 00:11:18 +08:00

504 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
#include <linux/fdtable.h>
#include <linux/anon_inodes.h>
#include <linux/uio.h>
#include "internal.h"
static int cachefiles_ondemand_fd_release(struct inode *inode,
struct file *file)
{
struct cachefiles_object *object = file->private_data;
struct cachefiles_cache *cache = object->volume->cache;
int object_id = object->ondemand_id;
struct cachefiles_req *req;
XA_STATE(xas, &cache->reqs, 0);
xa_lock(&cache->reqs);
object->ondemand_id = CACHEFILES_ONDEMAND_ID_CLOSED;
/*
* Flush all pending READ requests since their completion depends on
* anon_fd.
*/
xas_for_each(&xas, req, ULONG_MAX) {
if (req->msg.opcode == CACHEFILES_OP_READ) {
req->error = -EIO;
complete(&req->done);
xas_store(&xas, NULL);
}
}
xa_unlock(&cache->reqs);
xa_erase(&cache->ondemand_ids, object_id);
trace_cachefiles_ondemand_fd_release(object, object_id);
cachefiles_put_object(object, cachefiles_obj_put_ondemand_fd);
cachefiles_put_unbind_pincount(cache);
return 0;
}
static ssize_t cachefiles_ondemand_fd_write_iter(struct kiocb *kiocb,
struct iov_iter *iter)
{
struct cachefiles_object *object = kiocb->ki_filp->private_data;
struct cachefiles_cache *cache = object->volume->cache;
struct file *file = object->file;
size_t len = iter->count;
loff_t pos = kiocb->ki_pos;
const struct cred *saved_cred;
int ret;
if (!file)
return -ENOBUFS;
cachefiles_begin_secure(cache, &saved_cred);
ret = __cachefiles_prepare_write(object, file, &pos, &len, true);
cachefiles_end_secure(cache, saved_cred);
if (ret < 0)
return ret;
trace_cachefiles_ondemand_fd_write(object, file_inode(file), pos, len);
ret = __cachefiles_write(object, file, pos, iter, NULL, NULL);
if (!ret)
ret = len;
return ret;
}
static loff_t cachefiles_ondemand_fd_llseek(struct file *filp, loff_t pos,
int whence)
{
struct cachefiles_object *object = filp->private_data;
struct file *file = object->file;
if (!file)
return -ENOBUFS;
return vfs_llseek(file, pos, whence);
}
static long cachefiles_ondemand_fd_ioctl(struct file *filp, unsigned int ioctl,
unsigned long arg)
{
struct cachefiles_object *object = filp->private_data;
struct cachefiles_cache *cache = object->volume->cache;
struct cachefiles_req *req;
unsigned long id;
if (ioctl != CACHEFILES_IOC_READ_COMPLETE)
return -EINVAL;
if (!test_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags))
return -EOPNOTSUPP;
id = arg;
req = xa_erase(&cache->reqs, id);
if (!req)
return -EINVAL;
trace_cachefiles_ondemand_cread(object, id);
complete(&req->done);
return 0;
}
static const struct file_operations cachefiles_ondemand_fd_fops = {
.owner = THIS_MODULE,
.release = cachefiles_ondemand_fd_release,
.write_iter = cachefiles_ondemand_fd_write_iter,
.llseek = cachefiles_ondemand_fd_llseek,
.unlocked_ioctl = cachefiles_ondemand_fd_ioctl,
};
/*
* OPEN request Completion (copen)
* - command: "copen <id>,<cache_size>"
* <cache_size> indicates the object size if >=0, error code if negative
*/
int cachefiles_ondemand_copen(struct cachefiles_cache *cache, char *args)
{
struct cachefiles_req *req;
struct fscache_cookie *cookie;
char *pid, *psize;
unsigned long id;
long size;
int ret;
if (!test_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags))
return -EOPNOTSUPP;
if (!*args) {
pr_err("Empty id specified\n");
return -EINVAL;
}
pid = args;
psize = strchr(args, ',');
if (!psize) {
pr_err("Cache size is not specified\n");
return -EINVAL;
}
*psize = 0;
psize++;
ret = kstrtoul(pid, 0, &id);
if (ret)
return ret;
req = xa_erase(&cache->reqs, id);
if (!req)
return -EINVAL;
/* fail OPEN request if copen format is invalid */
ret = kstrtol(psize, 0, &size);
if (ret) {
req->error = ret;
goto out;
}
/* fail OPEN request if daemon reports an error */
if (size < 0) {
if (!IS_ERR_VALUE(size))
size = -EINVAL;
req->error = size;
goto out;
}
cookie = req->object->cookie;
cookie->object_size = size;
if (size)
clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);
else
set_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);
trace_cachefiles_ondemand_copen(req->object, id, size);
out:
complete(&req->done);
return ret;
}
static int cachefiles_ondemand_get_fd(struct cachefiles_req *req)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
struct cachefiles_open *load;
struct file *file;
u32 object_id;
int ret, fd;
object = cachefiles_grab_object(req->object,
cachefiles_obj_get_ondemand_fd);
cache = object->volume->cache;
ret = xa_alloc_cyclic(&cache->ondemand_ids, &object_id, NULL,
XA_LIMIT(1, INT_MAX),
&cache->ondemand_id_next, GFP_KERNEL);
if (ret < 0)
goto err;
fd = get_unused_fd_flags(O_WRONLY);
if (fd < 0) {
ret = fd;
goto err_free_id;
}
file = anon_inode_getfile("[cachefiles]", &cachefiles_ondemand_fd_fops,
object, O_WRONLY);
if (IS_ERR(file)) {
ret = PTR_ERR(file);
goto err_put_fd;
}
file->f_mode |= FMODE_PWRITE | FMODE_LSEEK;
fd_install(fd, file);
load = (void *)req->msg.data;
load->fd = fd;
req->msg.object_id = object_id;
object->ondemand_id = object_id;
cachefiles_get_unbind_pincount(cache);
trace_cachefiles_ondemand_open(object, &req->msg, load);
return 0;
err_put_fd:
put_unused_fd(fd);
err_free_id:
xa_erase(&cache->ondemand_ids, object_id);
err:
cachefiles_put_object(object, cachefiles_obj_put_ondemand_fd);
return ret;
}
ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache,
char __user *_buffer, size_t buflen)
{
struct cachefiles_req *req;
struct cachefiles_msg *msg;
unsigned long id = 0;
size_t n;
int ret = 0;
XA_STATE(xas, &cache->reqs, 0);
/*
* Search for a request that has not ever been processed, to prevent
* requests from being processed repeatedly.
*/
xa_lock(&cache->reqs);
req = xas_find_marked(&xas, UINT_MAX, CACHEFILES_REQ_NEW);
if (!req) {
xa_unlock(&cache->reqs);
return 0;
}
msg = &req->msg;
n = msg->len;
if (n > buflen) {
xa_unlock(&cache->reqs);
return -EMSGSIZE;
}
xas_clear_mark(&xas, CACHEFILES_REQ_NEW);
xa_unlock(&cache->reqs);
id = xas.xa_index;
msg->msg_id = id;
if (msg->opcode == CACHEFILES_OP_OPEN) {
ret = cachefiles_ondemand_get_fd(req);
if (ret)
goto error;
}
if (copy_to_user(_buffer, msg, n) != 0) {
ret = -EFAULT;
goto err_put_fd;
}
/* CLOSE request has no reply */
if (msg->opcode == CACHEFILES_OP_CLOSE) {
xa_erase(&cache->reqs, id);
complete(&req->done);
}
return n;
err_put_fd:
if (msg->opcode == CACHEFILES_OP_OPEN)
close_fd(((struct cachefiles_open *)msg->data)->fd);
error:
xa_erase(&cache->reqs, id);
req->error = ret;
complete(&req->done);
return ret;
}
typedef int (*init_req_fn)(struct cachefiles_req *req, void *private);
static int cachefiles_ondemand_send_req(struct cachefiles_object *object,
enum cachefiles_opcode opcode,
size_t data_len,
init_req_fn init_req,
void *private)
{
struct cachefiles_cache *cache = object->volume->cache;
struct cachefiles_req *req;
XA_STATE(xas, &cache->reqs, 0);
int ret;
if (!test_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags))
return 0;
if (test_bit(CACHEFILES_DEAD, &cache->flags))
return -EIO;
req = kzalloc(sizeof(*req) + data_len, GFP_KERNEL);
if (!req)
return -ENOMEM;
req->object = object;
init_completion(&req->done);
req->msg.opcode = opcode;
req->msg.len = sizeof(struct cachefiles_msg) + data_len;
ret = init_req(req, private);
if (ret)
goto out;
do {
/*
* Stop enqueuing the request when daemon is dying. The
* following two operations need to be atomic as a whole.
* 1) check cache state, and
* 2) enqueue request if cache is alive.
* Otherwise the request may be enqueued after xarray has been
* flushed, leaving the orphan request never being completed.
*
* CPU 1 CPU 2
* ===== =====
* test CACHEFILES_DEAD bit
* set CACHEFILES_DEAD bit
* flush requests in the xarray
* enqueue the request
*/
xas_lock(&xas);
if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
xas_unlock(&xas);
ret = -EIO;
goto out;
}
/* coupled with the barrier in cachefiles_flush_reqs() */
smp_mb();
if (opcode != CACHEFILES_OP_OPEN && object->ondemand_id <= 0) {
WARN_ON_ONCE(object->ondemand_id == 0);
xas_unlock(&xas);
ret = -EIO;
goto out;
}
xas.xa_index = 0;
xas_find_marked(&xas, UINT_MAX, XA_FREE_MARK);
if (xas.xa_node == XAS_RESTART)
xas_set_err(&xas, -EBUSY);
xas_store(&xas, req);
xas_clear_mark(&xas, XA_FREE_MARK);
xas_set_mark(&xas, CACHEFILES_REQ_NEW);
xas_unlock(&xas);
} while (xas_nomem(&xas, GFP_KERNEL));
ret = xas_error(&xas);
if (ret)
goto out;
wake_up_all(&cache->daemon_pollwq);
wait_for_completion(&req->done);
ret = req->error;
out:
kfree(req);
return ret;
}
static int cachefiles_ondemand_init_open_req(struct cachefiles_req *req,
void *private)
{
struct cachefiles_object *object = req->object;
struct fscache_cookie *cookie = object->cookie;
struct fscache_volume *volume = object->volume->vcookie;
struct cachefiles_open *load = (void *)req->msg.data;
size_t volume_key_size, cookie_key_size;
void *volume_key, *cookie_key;
/*
* Volume key is a NUL-terminated string. key[0] stores strlen() of the
* string, followed by the content of the string (excluding '\0').
*/
volume_key_size = volume->key[0] + 1;
volume_key = volume->key + 1;
/* Cookie key is binary data, which is netfs specific. */
cookie_key_size = cookie->key_len;
cookie_key = fscache_get_key(cookie);
if (!(object->cookie->advice & FSCACHE_ADV_WANT_CACHE_SIZE)) {
pr_err("WANT_CACHE_SIZE is needed for on-demand mode\n");
return -EINVAL;
}
load->volume_key_size = volume_key_size;
load->cookie_key_size = cookie_key_size;
memcpy(load->data, volume_key, volume_key_size);
memcpy(load->data + volume_key_size, cookie_key, cookie_key_size);
return 0;
}
static int cachefiles_ondemand_init_close_req(struct cachefiles_req *req,
void *private)
{
struct cachefiles_object *object = req->object;
int object_id = object->ondemand_id;
/*
* It's possible that object id is still 0 if the cookie looking up
* phase failed before OPEN request has ever been sent. Also avoid
* sending CLOSE request for CACHEFILES_ONDEMAND_ID_CLOSED, which means
* anon_fd has already been closed.
*/
if (object_id <= 0)
return -ENOENT;
req->msg.object_id = object_id;
trace_cachefiles_ondemand_close(object, &req->msg);
return 0;
}
struct cachefiles_read_ctx {
loff_t off;
size_t len;
};
static int cachefiles_ondemand_init_read_req(struct cachefiles_req *req,
void *private)
{
struct cachefiles_object *object = req->object;
struct cachefiles_read *load = (void *)req->msg.data;
struct cachefiles_read_ctx *read_ctx = private;
int object_id = object->ondemand_id;
/* Stop enqueuing requests when daemon has closed anon_fd. */
if (object_id <= 0) {
WARN_ON_ONCE(object_id == 0);
pr_info_once("READ: anonymous fd closed prematurely.\n");
return -EIO;
}
req->msg.object_id = object_id;
load->off = read_ctx->off;
load->len = read_ctx->len;
trace_cachefiles_ondemand_read(object, &req->msg, load);
return 0;
}
int cachefiles_ondemand_init_object(struct cachefiles_object *object)
{
struct fscache_cookie *cookie = object->cookie;
struct fscache_volume *volume = object->volume->vcookie;
size_t volume_key_size, cookie_key_size, data_len;
/*
* CacheFiles will firstly check the cache file under the root cache
* directory. If the coherency check failed, it will fallback to
* creating a new tmpfile as the cache file. Reuse the previously
* allocated object ID if any.
*/
if (object->ondemand_id > 0)
return 0;
volume_key_size = volume->key[0] + 1;
cookie_key_size = cookie->key_len;
data_len = sizeof(struct cachefiles_open) +
volume_key_size + cookie_key_size;
return cachefiles_ondemand_send_req(object, CACHEFILES_OP_OPEN,
data_len, cachefiles_ondemand_init_open_req, NULL);
}
void cachefiles_ondemand_clean_object(struct cachefiles_object *object)
{
cachefiles_ondemand_send_req(object, CACHEFILES_OP_CLOSE, 0,
cachefiles_ondemand_init_close_req, NULL);
}
int cachefiles_ondemand_read(struct cachefiles_object *object,
loff_t pos, size_t len)
{
struct cachefiles_read_ctx read_ctx = {pos, len};
return cachefiles_ondemand_send_req(object, CACHEFILES_OP_READ,
sizeof(struct cachefiles_read),
cachefiles_ondemand_init_read_req, &read_ctx);
}