diff options
Diffstat (limited to 'include/fuse_common.h')
| -rw-r--r-- | include/fuse_common.h | 39 |
1 files changed, 38 insertions, 1 deletions
diff --git a/include/fuse_common.h b/include/fuse_common.h index a614fb0..ba4b127 100644 --- a/include/fuse_common.h +++ b/include/fuse_common.h @@ -105,6 +105,11 @@ struct fuse_file_info { /** Requested poll events. Available in ->poll. Only set on kernels which support it. If unsupported, this field is set to zero. */ uint32_t poll_events; + + /** Passthrough backing file id. May be filled in by filesystem in + * create and open. It is used to create a passthrough connection + * between FUSE file and backing file. */ + int32_t backing_id; }; @@ -469,6 +474,18 @@ struct fuse_loop_config_v1 { #define FUSE_CAP_DIRECT_IO_ALLOW_MMAP (1 << 28) /** + * Indicates support for passthrough mode access for read/write operations. + * + * If this flag is set in the `capable` field of the `fuse_conn_info` + * structure, then the FUSE kernel module supports redirecting read/write + * operations to the backing file instead of letting them to be handled + * by the FUSE daemon. + * + * This feature is disabled by default. + */ +#define FUSE_CAP_PASSTHROUGH (1 << 29) + +/** * Ioctl flags * * FUSE_IOCTL_COMPAT: 32bit compat ioctl on 64bit machine @@ -598,9 +615,29 @@ struct fuse_conn_info { unsigned time_gran; /** + * When FUSE_CAP_PASSTHROUGH is enabled, this is the maximum allowed + * stacking depth of the backing files. In current kernel, the maximum + * allowed stack depth if FILESYSTEM_MAX_STACK_DEPTH (2), which includes + * the FUSE passthrough layer, so the maximum stacking depth for backing + * files is 1. + * + * The default is FUSE_BACKING_STACKED_UNDER (0), meaning that the + * backing files cannot be on a stacked filesystem, but another stacked + * filesystem can be stacked over this FUSE passthrough filesystem. + * + * Set this to FUSE_BACKING_STACKED_OVER (1) if backing files may be on + * a stacked filesystem, such as overlayfs or another FUSE passthrough. + * In this configuration, another stacked filesystem cannot be stacked + * over this FUSE passthrough filesystem. + */ +#define FUSE_BACKING_STACKED_UNDER (0) +#define FUSE_BACKING_STACKED_OVER (1) + unsigned max_backing_stack_depth; + + /** * For future use. */ - unsigned reserved[22]; + unsigned reserved[21]; }; struct fuse_session; |