Implement .demand_read() callback for cachefiels backend.
.demand_read() callback is responsible for notifying user daemon the
pending request to process, and will get blocked until user daemon has
prepared data and filled the hole.
Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
---
fs/cachefiles/internal.h | 12 +++++++++
fs/cachefiles/io.c | 56 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 68 insertions(+)
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index af8ac8107f77..eeb6ad7dcd49 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -61,6 +61,18 @@ struct cachefiles_object {
#define CACHEFILES_OBJECT_USING_TMPFILE 0 /* Have an unlinked tmpfile */
};
+struct cachefiles_req_in {
+ uint64_t id;
+ uint64_t off;
+ uint64_t len;
+ char path[NAME_MAX];
+};
+
+struct cachefiles_req {
+ struct completion done;
+ struct cachefiles_req_in req_in;
+};
+
/*
* Cache files cache definition
*/
diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
index 60b1eac2ce78..376603e5ed99 100644
--- a/fs/cachefiles/io.c
+++ b/fs/cachefiles/io.c
@@ -539,12 +539,68 @@ static void cachefiles_end_operation(struct netfs_cache_resources *cres)
fscache_end_cookie_access(fscache_cres_cookie(cres), fscache_access_io_end);
}
+static struct cachefiles_req *cachefiles_alloc_req(struct cachefiles_object *object,
+ loff_t start_pos,
+ size_t len)
+{
+ struct cachefiles_req *req;
+ struct cachefiles_req_in *req_in;
+
+ req = kzalloc(sizeof(*req), GFP_KERNEL);
+ if (!req)
+ return NULL;
+
+ req_in = &req->req_in;
+
+ req_in->off = start_pos;
+ req_in->len = len;
+ strncpy(req_in->path, object->d_name, sizeof(req_in->path));
+
+ init_completion(&req->done);
+
+ return req;
+}
+
+int cachefiles_demand_read(struct netfs_cache_resources *cres,
+ loff_t start_pos, size_t len)
+{
+ struct cachefiles_object *object;
+ struct cachefiles_cache *cache;
+ struct cachefiles_req *req;
+ int ret;
+
+ object = cachefiles_cres_object(cres);
+ cache = object->volume->cache;
+
+ req = cachefiles_alloc_req(object, start_pos, len);
+ if (!req)
+ return -ENOMEM;
+
+ spin_lock(&cache->reqs_lock);
+ ret = idr_alloc(&cache->reqs, req, 0, 0, GFP_KERNEL);
+ if (ret >= 0)
+ req->req_in.id = ret;
+ spin_unlock(&cache->reqs_lock);
+ if (ret < 0) {
+ kfree(req);
+ return -ENOMEM;
+ }
+
+ wake_up_all(&cache->daemon_pollwq);
+
+ wait_for_completion(&req->done);
+ kfree(req);
+
+ return 0;
+}
+
static const struct netfs_cache_ops cachefiles_netfs_cache_ops = {
.end_operation = cachefiles_end_operation,
.read = cachefiles_read,
.write = cachefiles_write,
.prepare_read = cachefiles_prepare_read,
.prepare_write = cachefiles_prepare_write,
+ .demand_read = cachefiles_demand_read,
};
/*
--
2.27.0
--
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