@@ -47,6 +47,7 @@ static int cachefiles_daemon_bind(struct cachefiles_cache *, char *);
static void cachefiles_daemon_unbind(struct cachefiles_cache *);
#ifdef CONFIG_CACHEFILES_ONDEMAND
static int cachefiles_ondemand_cinit(struct cachefiles_cache *, char *);
+static int cachefiles_ondemand_cread(struct cachefiles_cache *, char *);
#endif
static unsigned long cachefiles_open;
@@ -82,6 +83,7 @@ static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
{ "tag", cachefiles_daemon_tag },
#ifdef CONFIG_CACHEFILES_ONDEMAND
{ "cinit", cachefiles_ondemand_cinit },
+ { "cread", cachefiles_ondemand_cread },
#endif
{ "", NULL }
};
@@ -264,6 +266,36 @@ static int cachefiles_ondemand_cinit(struct cachefiles_cache *cache, char *args)
return ret;
}
+/*
+ * Read request completion
+ * - command: "cread <id>"
+ */
+static int cachefiles_ondemand_cread(struct cachefiles_cache *cache, char *args)
+{
+ struct cachefiles_req *req;
+ unsigned long id;
+ int ret;
+
+ if (!test_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags))
+ return -EOPNOTSUPP;
+
+ if (!*args) {
+ pr_err("Empty id specified\n");
+ return -EINVAL;
+ }
+
+ ret = kstrtoul(args, 0, &id);
+ if (ret)
+ return ret;
+
+ req = xa_erase(&cache->reqs, id);
+ if (!req)
+ return -EINVAL;
+
+ complete(&req->done);
+ return 0;
+}
+
static int cachefiles_ondemand_get_fd(struct cachefiles_req *req)
{
struct cachefiles_object *object;
@@ -471,6 +503,28 @@ static int init_close_req(struct cachefiles_req *req, void *private)
return 0;
}
+struct cachefiles_read_ctx {
+ loff_t off;
+ size_t len;
+};
+
+static int 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 fd = object->fd;
+
+ /* Stop enqueuig request when daemon closes anon_fd prematurely. */
+ if (WARN_ON_ONCE(fd == -1))
+ return -EIO;
+
+ load->off = read_ctx->off;
+ load->len = read_ctx->len;
+ load->fd = fd;
+ return 0;
+}
+
int cachefiles_ondemand_init_object(struct cachefiles_object *object)
{
struct fscache_cookie *cookie = object->cookie;
@@ -504,6 +558,17 @@ void cachefiles_ondemand_cleanup_object(struct cachefiles_object *object)
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),
+ init_read_req, &read_ctx);
+}
+
#else
static inline void cachefiles_ondemand_open(struct cachefiles_cache *cache) {}
static inline void cachefiles_ondemand_release(struct cachefiles_cache *cache) {}
@@ -168,6 +168,8 @@ extern const struct file_operations cachefiles_daemon_fops;
#ifdef CONFIG_CACHEFILES_ONDEMAND
extern int cachefiles_ondemand_init_object(struct cachefiles_object *object);
extern void cachefiles_ondemand_cleanup_object(struct cachefiles_object *object);
+extern int cachefiles_ondemand_read(struct cachefiles_object *object,
+ loff_t pos, size_t len);
#else
static inline
@@ -178,6 +180,13 @@ int cachefiles_ondemand_init_object(struct cachefiles_object *object)
static inline
void cachefiles_ondemand_cleanup_object(struct cachefiles_object *object) {}
+
+static inline
+int cachefiles_ondemand_read(struct cachefiles_object *object,
+ loff_t pos, size_t len)
+{
+ return -EOPNOTSUPP;
+}
#endif
/*
@@ -95,6 +95,7 @@ static int cachefiles_read(struct netfs_cache_resources *cres,
file, file_inode(file)->i_ino, start_pos, len,
i_size_read(file_inode(file)));
+retry:
/* If the caller asked us to seek for data before doing the read, then
* we should do that now. If we find a gap, we fill it with zeros.
*/
@@ -119,6 +120,16 @@ static int cachefiles_read(struct netfs_cache_resources *cres,
if (read_hole == NETFS_READ_HOLE_FAIL)
goto presubmission_error;
+ if (read_hole == NETFS_READ_HOLE_ONDEMAND) {
+ if (!cachefiles_ondemand_read(object, off, len)) {
+ /* fail the read if no progress achieved */
+ read_hole = NETFS_READ_HOLE_FAIL;
+ goto retry;
+ }
+
+ goto presubmission_error;
+ }
+
iov_iter_zero(len, iter);
skipped = len;
ret = 0;
@@ -203,6 +203,7 @@ enum netfs_read_from_hole {
NETFS_READ_HOLE_IGNORE,
NETFS_READ_HOLE_CLEAR,
NETFS_READ_HOLE_FAIL,
+ NETFS_READ_HOLE_ONDEMAND,
};
/*
@@ -9,6 +9,7 @@
enum cachefiles_opcode {
CACHEFILES_OP_OPEN,
CACHEFILES_OP_CLOSE,
+ CACHEFILES_OP_READ,
};
/*
@@ -41,4 +42,10 @@ struct cachefiles_close {
__u32 fd;
};
+struct cachefiles_read {
+ __u64 off;
+ __u64 len;
+ __u32 fd;
+};
+
#endif
Implement the data plane of on-demand read mode. A new NETFS_READ_HOLE_ONDEMAND flag is introduced to indicate that on-demand read should be done when a cache miss encountered. In this case, the read routine will send a READ request to user daemon, along with the anonymous fd and the file range that shall be read. Now user daemon is responsible for fetching data in the given file range, and then writing the fetched data into cache file with the given anonymous fd. After sending the READ request, the read routine will hang there, until the READ request is handled by user daemon. Then it will retry to read from the same file range. If a cache miss is encountered again on the same file range, the read routine will fail then. Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com> --- fs/cachefiles/daemon.c | 65 +++++++++++++++++++++++++++++++++ fs/cachefiles/internal.h | 9 +++++ fs/cachefiles/io.c | 11 ++++++ include/linux/netfs.h | 1 + include/uapi/linux/cachefiles.h | 7 ++++ 5 files changed, 93 insertions(+)