kernel/linux.git/fs/fuse/passthrough.c, branch v6.18.22

fuse: move the backing file idr and code into a new source file

2025-09-25T14:06:02+00:00

iomap support for fuse is also going to want the ability to attach backing files to a fuse filesystem. Move the fuse_backing code into a separate file so that both can use it. Signed-off-by: Darrick J. Wong Reviewed-by: Amir Goldstein Signed-off-by: Miklos Szeredi

fuse: remove unused 'inode' parameter in fuse_passthrough_open

2025-08-27T12:29:44+00:00

The 'inode' parameter in fuse_passthrough_open() is never referenced in the function implementation. Signed-off-by: Chunsheng Luo Reviewed-by: Joanne Koong Signed-off-by: Miklos Szeredi

fuse: do not allow mapping a non-regular backing file

2025-08-26T10:43:31+00:00

We do not support passthrough operations other than read/write on regular file, so allowing non-regular backing files makes no sense. Fixes: efad7153bf93 ("fuse: allow O_PATH fd for FUSE_DEV_IOC_BACKING_OPEN") Cc: stable@vger.kernel.org Signed-off-by: Amir Goldstein Reviewed-by: Bernd Schubert Signed-off-by: Miklos Szeredi

backing-file: clean up the API

2024-11-11T09:45:03+00:00

- Pass iocb to ctx->end_write() instead of file + pos - Get rid of ctx->user_file, which is redundant most of the time - Instead pass iocb to backing_file_splice_read and backing_file_splice_write Signed-off-by: Miklos Szeredi Signed-off-by: Amir Goldstein

fuse: remove stray debug line

2024-10-25T15:05:49+00:00

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

fuse: update inode size after extending passthrough write

2024-10-16T11:18:21+00:00

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 Closes: https://github.com/libfuse/libfuse/issues/1048 Fixes: 57e1176e6086 ("fuse: implement read/write passthrough") Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

fs: pass offset and result to backing_file end_write() callback

2024-10-16T11:17:45+00:00

This is needed for extending fuse inode size after fuse passthrough write. Suggested-by: Miklos Szeredi Link: https://lore.kernel.org/linux-fsdevel/CAJfpegs=cvZ_NYy6Q_D42XhYS=Sjj5poM1b5TzXzOVvX=R36aA@mail.gmail.com/ Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

fuse: allow O_PATH fd for FUSE_DEV_IOC_BACKING_OPEN

2024-09-19T07:37:13+00:00

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 Signed-off-by: Miklos Szeredi

fuse: verify zero padding in fuse_backing_map

2024-04-22T15:13:43+00:00

To allow us extending the interface in the future. Fixes: 44350256ab94 ("fuse: implement ioctls to manage backing files") Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

fuse: implement passthrough for mmap

2024-03-05T12:40:42+00:00

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 Signed-off-by: Miklos Szeredi