diff options
| author | Amir Goldstein <amir73il@gmail.com> | 2023-09-11 17:09:27 +0300 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2024-03-05 13:40:36 +0100 |
| commit | 44350256ab943d424d70aa60a34f45060b3a36e8 (patch) | |
| tree | 65567a0a2cf44561b25f201f1e81540af1ed69af /include/uapi/linux | |
| parent | 7dc4e97a4f9a55bae6ed6ab3f96c92921259d59f (diff) | |
fuse: implement ioctls to manage backing files
FUSE server calls the FUSE_DEV_IOC_BACKING_OPEN ioctl with a backing file
descriptor. If the call succeeds, a backing file identifier is returned.
A later change will be using this backing file id in a reply to OPEN
request with the flag FOPEN_PASSTHROUGH to setup passthrough of file
operations on the open FUSE file to the backing file.
The FUSE server should call FUSE_DEV_IOC_BACKING_CLOSE ioctl to close the
backing file by its id.
This can be done at any time, but if an open reply with FOPEN_PASSTHROUGH
flag is still in progress, the open may fail if the backing file is
closed before the fuse file was opened.
Setting up backing files requires a server with CAP_SYS_ADMIN privileges.
For the backing file to be successfully setup, the backing file must
implement both read_iter and write_iter file operations.
The limitation on the level of filesystem stacking allowed for the
backing file is enforced before setting up the backing file.
Signed-off-by: Alessio Balsini <balsini@android.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'include/uapi/linux')
| -rw-r--r-- | include/uapi/linux/fuse.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index 7bb6219cfda0..1162a47b6a42 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -1057,9 +1057,18 @@ struct fuse_notify_retrieve_in { uint64_t dummy4; }; +struct fuse_backing_map { + int32_t fd; + uint32_t flags; + uint64_t padding; +}; + /* Device ioctls: */ #define FUSE_DEV_IOC_MAGIC 229 #define FUSE_DEV_IOC_CLONE _IOR(FUSE_DEV_IOC_MAGIC, 0, uint32_t) +#define FUSE_DEV_IOC_BACKING_OPEN _IOW(FUSE_DEV_IOC_MAGIC, 1, \ + struct fuse_backing_map) +#define FUSE_DEV_IOC_BACKING_CLOSE _IOW(FUSE_DEV_IOC_MAGIC, 2, uint32_t) struct fuse_lseek_in { uint64_t fh; |