fs: introduce f_op->mmap_capabilities for nommu mmap support
Since "BDI: Provide backing device capability information [try #3]" the
backing_dev_info structure also provides flags for the kind of mmap
operation available in a nommu environment, which is entirely unrelated
to it's original purpose.
Introduce a new nommu-only file operation to provide this information to
the nommu mmap code instead. Splitting this from the backing_dev_info
structure allows to remove lots of backing_dev_info instance that aren't
otherwise needed, and entirely gets rid of the concept of providing a
backing_dev_info for a character device. It also removes the need for
the mtd_inodefs filesystem.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Acked-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
index d365b1c..ad4d712 100644
--- a/fs/ramfs/inode.c
+++ b/fs/ramfs/inode.c
@@ -50,14 +50,6 @@
.set_page_dirty = __set_page_dirty_no_writeback,
};
-static struct backing_dev_info ramfs_backing_dev_info = {
- .name = "ramfs",
- .ra_pages = 0, /* No readahead */
- .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK |
- BDI_CAP_MAP_DIRECT | BDI_CAP_MAP_COPY |
- BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP,
-};
-
struct inode *ramfs_get_inode(struct super_block *sb,
const struct inode *dir, umode_t mode, dev_t dev)
{
@@ -67,7 +59,7 @@
inode->i_ino = get_next_ino();
inode_init_owner(inode, dir, mode);
inode->i_mapping->a_ops = &ramfs_aops;
- inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info;
+ inode->i_mapping->backing_dev_info = &noop_backing_dev_info;
mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
mapping_set_unevictable(inode->i_mapping);
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
@@ -267,19 +259,9 @@
int __init init_ramfs_fs(void)
{
static unsigned long once;
- int err;
if (test_and_set_bit(0, &once))
return 0;
-
- err = bdi_init(&ramfs_backing_dev_info);
- if (err)
- return err;
-
- err = register_filesystem(&ramfs_fs_type);
- if (err)
- bdi_destroy(&ramfs_backing_dev_info);
-
- return err;
+ return register_filesystem(&ramfs_fs_type);
}
fs_initcall(init_ramfs_fs);