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2024-10-25fuse: remove stray debug lineMiklos Szeredi1-1/+0
It wasn't there when the patch was posted for review, but somehow made it into the pull. Link: https://lore.kernel.org/all/20240913104703.1673180-1-mszeredi@redhat.com/ Fixes: efad7153bf93 ("fuse: allow O_PATH fd for FUSE_DEV_IOC_BACKING_OPEN") Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2024-10-16fuse: update inode size after extending passthrough writeAmir Goldstein1-1/+1
yangyun reported that libfuse test test_copy_file_range() copies zero bytes from a newly written file when fuse passthrough is enabled. The reason is that extending passthrough write is not updating the fuse inode size and when vfs_copy_file_range() observes a zero size inode, it returns without calling the filesystem copy_file_range() method. Fix this by adjusting the fuse inode size after an extending passthrough write. This does not provide cache coherency of fuse inode attributes and backing inode attributes, but it should prevent situations where fuse inode size is too small, causing read/copy to be wrongly shortened. Reported-by: yangyun <yangyun50@huawei.com> Closes: https://github.com/libfuse/libfuse/issues/1048 Fixes: 57e1176e6086 ("fuse: implement read/write passthrough") Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2024-10-16fs: pass offset and result to backing_file end_write() callbackAmir Goldstein1-3/+3
This is needed for extending fuse inode size after fuse passthrough write. Suggested-by: Miklos Szeredi <miklos@szeredi.hu> Link: https://lore.kernel.org/linux-fsdevel/CAJfpegs=cvZ_NYy6Q_D42XhYS=Sjj5poM1b5TzXzOVvX=R36aA@mail.gmail.com/ Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2024-09-19fuse: allow O_PATH fd for FUSE_DEV_IOC_BACKING_OPENMiklos Szeredi1-5/+2
Only f_path is used from backing files registered with FUSE_DEV_IOC_BACKING_OPEN, so it makes sense to allow O_PATH descriptors. O_PATH files have an empty f_op, so don't check read_iter/write_iter. Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2024-04-22fuse: verify zero padding in fuse_backing_mapAmir Goldstein1-1/+1
To allow us extending the interface in the future. Fixes: 44350256ab94 ("fuse: implement ioctls to manage backing files") Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2024-03-05fuse: implement passthrough for mmapAmir Goldstein1-0/+16
An mmap request for a file open in passthrough mode, maps the memory directly to the backing file. An mmap of a file in direct io mode, usually uses cached mmap and puts the inode in caching io mode, which denies new passthrough opens of that inode, because caching io mode is conflicting with passthrough io mode. For the same reason, trying to mmap a direct io file, while there is a passthrough file open on the same inode will fail with -ENODEV. An mmap of a file in direct io mode, also needs to wait for parallel dio writes in-progress to complete. If a passthrough file is opened, while an mmap of another direct io file is waiting for parallel dio writes to complete, the wait is aborted and mmap fails with -ENODEV. A FUSE server that uses passthrough and direct io opens on the same inode that may also be mmaped, is advised to provide a backing fd also for the files that are open in direct io mode (i.e. use the flags combination FOPEN_DIRECT_IO | FOPEN_PASSTHROUGH), so that mmap will always use the backing file, even if read/write do not passthrough. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2024-03-05fuse: implement splice read/write passthroughAmir Goldstein1-0/+45
This allows passing fstests generic/249 and generic/591. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2024-03-05fuse: implement read/write passthroughAmir Goldstein1-0/+69
Use the backing file read/write helpers to implement read/write passthrough to a backing file. After read/write, we invalidate a/c/mtime/size attributes. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2024-03-05fuse: implement open in passthrough modeAmir Goldstein1-0/+59
After getting a backing file id with FUSE_DEV_IOC_BACKING_OPEN ioctl, a FUSE server can reply to an OPEN request with flag FOPEN_PASSTHROUGH and the backing file id. The FUSE server should reuse the same backing file id for all the open replies of the same FUSE inode and open will fail (with -EIO) if a the server attempts to open the same inode with conflicting io modes or to setup passthrough to two different backing files for the same FUSE inode. Using the same backing file id for several different inodes is allowed. Opening a new file with FOPEN_DIRECT_IO for an inode that is already open for passthrough is allowed, but only if the FOPEN_PASSTHROUGH flag and correct backing file id are specified as well. The read/write IO of such files will not use passthrough operations to the backing file, but mmap, which does not support direct_io, will use the backing file insead of using the page cache as it always did. Even though all FUSE passthrough files of the same inode use the same backing file as a backing inode reference, each FUSE file opens a unique instance of a backing_file object to store the FUSE path that was used to open the inode and the open flags of the specific open file. The per-file, backing_file object is released along with the FUSE file. The inode associated fuse_backing object is released when the last FUSE passthrough file of that inode is released AND when the backing file id is closed by the server using the FUSE_DEV_IOC_BACKING_CLOSE ioctl. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2024-03-05fuse: implement ioctls to manage backing filesAmir Goldstein1-0/+136
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>
2024-02-23fuse: introduce FUSE_PASSTHROUGH capabilityAmir Goldstein1-0/+30
FUSE_PASSTHROUGH capability to passthrough FUSE operations to backing files will be made available with kernel config CONFIG_FUSE_PASSTHROUGH. When requesting FUSE_PASSTHROUGH, userspace needs to specify the max_stack_depth that is allowed for FUSE on top of backing files. Introduce the flag FOPEN_PASSTHROUGH and backing_id to fuse_open_out argument that can be used when replying to OPEN request, to setup passthrough of io operations on the fuse inode to a backing file. Introduce a refcounted fuse_backing object that will be used to associate an open backing file with a fuse inode. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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