fuse: allow private mappings of "direct_io" files

Allow MAP_PRIVATE mmaps of "direct_io" files.  This is necessary for
execute support.

MAP_SHARED mappings require some sort of coherency between the
underlying file and the mapping.  With "direct_io" it is difficult to
provide this, so for the moment just disallow shared (read-write and
read-only) mappings altogether.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 78a2c83..2b25133 100644 (file)
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1292,6 +1292,15 @@ static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
        return 0;
 }
 
+static int fuse_direct_mmap(struct file *file, struct vm_area_struct *vma)
+{
+       /* Can't provide the coherency needed for MAP_SHARED */
+       if (vma->vm_flags & VM_MAYSHARE)
+               return -ENODEV;
+
+       return generic_file_mmap(file, vma);
+}
+
 static int convert_fuse_file_lock(const struct fuse_file_lock *ffl,
                                  struct file_lock *fl)
 {
@@ -1926,6 +1935,7 @@ static const struct file_operations fuse_direct_io_file_operations = {
        .llseek         = fuse_file_llseek,
        .read           = fuse_direct_read,
        .write          = fuse_direct_write,
+       .mmap           = fuse_direct_mmap,
        .open           = fuse_open,
        .flush          = fuse_flush,
        .release        = fuse_release,
@@ -1935,7 +1945,7 @@ static const struct file_operations fuse_direct_io_file_operations = {
        .unlocked_ioctl = fuse_file_ioctl,
        .compat_ioctl   = fuse_file_compat_ioctl,
        .poll           = fuse_file_poll,
-       /* no mmap and splice_read */
+       /* no splice_read */
 };
 
 static const struct address_space_operations fuse_file_aops  = {