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 /fs/fuse/inode.c | |
| 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 'fs/fuse/inode.c')
| -rw-r--r-- | fs/fuse/inode.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index c771bd3c1336..0186df5fc9ea 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -930,6 +930,9 @@ void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm, fc->max_pages = FUSE_DEFAULT_MAX_PAGES_PER_REQ; fc->max_pages_limit = FUSE_MAX_MAX_PAGES; + if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH)) + fuse_backing_files_init(fc); + INIT_LIST_HEAD(&fc->mounts); list_add(&fm->fc_entry, &fc->mounts); fm->fc = fc; @@ -953,6 +956,8 @@ void fuse_conn_put(struct fuse_conn *fc) WARN_ON(atomic_read(&bucket->count) != 1); kfree(bucket); } + if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH)) + fuse_backing_files_free(fc); fc->release(fc); } } |