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 <[email protected]>
Reviewed-by: Tejun Heo <[email protected]>
Acked-by: Brian Norris <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This commit is contained in:
Christoph Hellwig 2015-01-14 10:42:32 +01:00 • committed by Jens Axboe
commit b4caecd480
32 changed files with 169 additions and 346 deletions

View file

@ -165,15 +165,6 @@ static struct vfsmount *aio_mnt;
static const struct file_operations aio_ring_fops;
static const struct address_space_operations aio_ctx_aops;
/* Backing dev info for aio fs.
* -no dirty page accounting or writeback happens
*/
static struct backing_dev_info aio_fs_backing_dev_info = {
.name = "aiofs",
.state = 0,
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_MAP_COPY,
};
static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
{
struct qstr this = QSTR_INIT("[aio]", 5);
@ -185,7 +176,7 @@ static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
inode->i_mapping->a_ops = &aio_ctx_aops;
inode->i_mapping->private_data = ctx;
inode->i_mapping->backing_dev_info = &aio_fs_backing_dev_info;
inode->i_mapping->backing_dev_info = &noop_backing_dev_info;
inode->i_size = PAGE_SIZE * nr_pages;
path.dentry = d_alloc_pseudo(aio_mnt->mnt_sb, &this);
@ -230,9 +221,6 @@ static int __init aio_setup(void)
if (IS_ERR(aio_mnt))
panic("Failed to create aio fs mount.");
if (bdi_init(&aio_fs_backing_dev_info))
panic("Failed to init aio fs backing dev info.");
kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);