From fda0b98ef0a6a2e3fe328b869d53002c8c82001b Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Fri, 9 Feb 2024 17:16:49 +0200 Subject: fuse: implement passthrough for mmap 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 --- fs/fuse/fuse_i.h | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/fuse/fuse_i.h') diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 53ac73739788..7bd3552b1e80 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -1474,5 +1474,6 @@ ssize_t fuse_passthrough_splice_read(struct file *in, loff_t *ppos, ssize_t fuse_passthrough_splice_write(struct pipe_inode_info *pipe, struct file *out, loff_t *ppos, size_t len, unsigned int flags); +ssize_t fuse_passthrough_mmap(struct file *file, struct vm_area_struct *vma); #endif /* _FS_FUSE_I_H */ -- cgit v1.2.3-58-ga151