diff options
| author | Hao Xu <howeyxu@tencent.com> | 2023-08-01 16:06:46 +0800 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2023-08-16 12:39:16 +0200 |
| commit | e78662e818f9478e70912cc2970ca632ec9f3635 (patch) | |
| tree | 314381c812fb07d72c61135a69fe27caf50a191e /fs/fuse/file.c | |
| parent | 80e4f25262f9f1a5f08154fafaa6ac4371043d35 (diff) | |
fuse: add a new fuse init flag to relax restrictions in no cache mode
FOPEN_DIRECT_IO is usually set by fuse daemon to indicate need of strong
coherency, e.g. network filesystems. Thus shared mmap is disabled since it
leverages page cache and may write to it, which may cause inconsistence.
But FOPEN_DIRECT_IO can be used not for coherency but to reduce memory
footprint as well, e.g. reduce guest memory usage with virtiofs.
Therefore, add a new fuse init flag FUSE_DIRECT_IO_RELAX to relax
restrictions in that mode, currently, it allows shared mmap. One thing to
note is to make sure it doesn't break coherency in your use case.
Signed-off-by: Hao Xu <howeyxu@tencent.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/fuse/file.c')
| -rw-r--r-- | fs/fuse/file.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 1aa7dde665aa..e6034ce698e9 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -2451,14 +2451,17 @@ static const struct vm_operations_struct fuse_file_vm_ops = { static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma) { struct fuse_file *ff = file->private_data; + struct fuse_conn *fc = ff->fm->fc; /* DAX mmap is superior to direct_io mmap */ if (FUSE_IS_DAX(file_inode(file))) return fuse_dax_mmap(file, vma); if (ff->open_flags & FOPEN_DIRECT_IO) { - /* Can't provide the coherency needed for MAP_SHARED */ - if (vma->vm_flags & VM_MAYSHARE) + /* Can't provide the coherency needed for MAP_SHARED + * if FUSE_DIRECT_IO_RELAX isn't set. + */ + if ((vma->vm_flags & VM_MAYSHARE) && !fc->direct_io_relax) return -ENODEV; invalidate_inode_pages2(file->f_mapping); |