diff options
| -rw-r--r-- | jni/FuseDaemon.cpp | 27 |
1 files changed, 25 insertions, 2 deletions
diff --git a/jni/FuseDaemon.cpp b/jni/FuseDaemon.cpp index fb0468c5b..a89819e52 100644 --- a/jni/FuseDaemon.cpp +++ b/jni/FuseDaemon.cpp @@ -713,6 +713,28 @@ namespace fuse { * */ +bool IsUpstreamPassthroughSupported() { + // Upstream passthrough requires some modifications to work. If those are present, + // /sys/fs/fuse/fuse_passthrough will read 'supported\n' + // - see fs/fuse/inode.c in the kernel source + + string contents; + const char* filename = "/sys/fs/fuse/features/fuse_passthrough"; + if (!android::base::ReadFileToString(filename, &contents)) { + LOG(INFO) << "fuse-passthrough is disabled because " << filename << " cannot be read"; + return false; + } + + if (contents == "supported\n") { + LOG(INFO) << "fuse-passthrough is enabled because " << filename << " reads 'supported'"; + return true; + } else { + LOG(INFO) << "fuse-passthrough is disabled because " << filename + << " does not read 'supported'"; + return false; + } +} + static void pf_init(void* userdata, struct fuse_conn_info* conn) { struct fuse* fuse = reinterpret_cast<struct fuse*>(userdata); @@ -752,7 +774,8 @@ static void pf_init(void* userdata, struct fuse_conn_info* conn) { // b. Files requiring redaction are still faster than no-passthrough devices that use // direct_io disable_splice_write = true; - } else if (conn->capable & FUSE_CAP_PASSTHROUGH_UPSTREAM) { + } else if ((conn->capable & FUSE_CAP_PASSTHROUGH_UPSTREAM) && + IsUpstreamPassthroughSupported()) { mask |= FUSE_CAP_PASSTHROUGH_UPSTREAM; disable_splice_write = true; fuse->upstream_passthrough = true; @@ -1451,7 +1474,7 @@ static handle* create_handle_for_node(struct fuse* fuse, const string& path, int } if (fuse->passthrough && allow_passthrough) { - *keep_cache = transforms_complete && !fuse->upstream_passthrough; + *keep_cache = transforms_complete; // We only enabled passthrough iff these 2 conditions hold // 1. Redaction is not needed // 2. Node transforms are completed, e.g transcoding. |