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-rw-r--r--fs/cachefiles/ondemand.c514
1 files changed, 514 insertions, 0 deletions
diff --git a/fs/cachefiles/ondemand.c b/fs/cachefiles/ondemand.c
new file mode 100644
index 000000000..0254ed39f
--- /dev/null
+++ b/fs/cachefiles/ondemand.c
@@ -0,0 +1,514 @@
+// 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.object_id == object_id &&
+ 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)) {
+ req->error = -EINVAL;
+ ret = -EINVAL;
+ } else {
+ req->error = size;
+ ret = 0;
+ }
+ 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, cache->req_id_next);
+
+ /*
+ * Cyclically search for a request that has not ever been processed,
+ * to prevent requests from being processed repeatedly, and make
+ * request distribution fair.
+ */
+ xa_lock(&cache->reqs);
+ req = xas_find_marked(&xas, UINT_MAX, CACHEFILES_REQ_NEW);
+ if (!req && cache->req_id_next > 0) {
+ xas_set(&xas, 0);
+ req = xas_find_marked(&xas, cache->req_id_next - 1, 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);
+ cache->req_id_next = xas.xa_index + 1;
+ 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);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-01 02:51:30 +0000