[PATCH 3.12 77/83] rework aio migrate pages to use aio fs

Greg Kroah-Hartman
2013-12-06T22:27:36Z

From: Benjamin LaHaise <bcrl@kvack.org>

commit 71ad7490c1f32bd7829df76360f9fa17829868f3 upstream.

Don't abuse anon_inodes.c to host private files needed by aio;
we can bloody well declare a mini-fs of our own instead of
patching up what anon_inodes can create for us.

Tested-by: Benjamin LaHaise <bcrl@kvack.org>
Acked-by: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/aio.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 57 insertions(+), 6 deletions(-)

--- a/fs/aio.c
+++ b/fs/aio.c
@@ -36,10 +36,10 @@
#include <linux/eventfd.h>
#include <linux/blkdev.h>
#include <linux/compat.h>
-#include <linux/anon_inodes.h>
#include <linux/migrate.h>
#include <linux/ramfs.h>
#include <linux/percpu-refcount.h>
+#include <linux/mount.h>

#include <asm/kmap_types.h>
#include <asm/uaccess.h>
@@ -153,12 +153,67 @@ unsigned long aio_max_nr = 0x10000; /* s
static struct kmem_cache *kiocb_cachep;
static struct kmem_cache *kioctx_cachep;

+static struct vfsmount *aio_mnt;
+
+static const struct file_operations aio_ring_fops;
+static const struct address_space_operations aio_ctx_aops;
+
+static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
+{
+ struct qstr this = QSTR_INIT("[aio]", 5);
+ struct file *file;
+ struct path path;
+ struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
+ if (!inode)
+ return ERR_PTR(-ENOMEM);
+
+ inode->i_mapping->a_ops = &aio_ctx_aops;
+ inode->i_mapping->private_data = ctx;
+ inode->i_size = PAGE_SIZE * nr_pages;
+
+ path.dentry = d_alloc_pseudo(aio_mnt->mnt_sb, &this);
+ if (!path.dentry) {
+ iput(inode);
+ return ERR_PTR(-ENOMEM);
+ }
+ path.mnt = mntget(aio_mnt);
+
+ d_instantiate(path.dentry, inode);
+ file = alloc_file(&path, FMODE_READ | FMODE_WRITE, &aio_ring_fops);
+ if (IS_ERR(file)) {
+ path_put(&path);
+ return file;
+ }
+
+ file->f_flags = O_RDWR;
+ file->private_data = ctx;
+ return file;
+}
+
+static struct dentry *aio_mount(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data)
+{
+ static const struct dentry_operations ops = {
+ .d_dname = simple_dname,
+ };
+ return mount_pseudo(fs_type, "aio:", NULL, &ops, 0xa10a10a1);
+}
+
/* aio_setup
* Creates the slab caches used by the aio routines, panic on
* failure as this is done early during the boot sequence.
*/
static int __init aio_setup(void)
{
+ static struct file_system_type aio_fs = {
+ .name = "aio",
+ .mount = aio_mount,
+ .kill_sb = kill_anon_super,
+ };
+ aio_mnt = kern_mount(&aio_fs);
+ if (IS_ERR(aio_mnt))
+ panic("Failed to create aio fs mount.");
+
kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);

@@ -284,16 +339,12 @@ static int aio_setup_ring(struct kioctx
if (nr_pages < 0)
return -EINVAL;

- file = anon_inode_getfile_private("[aio]", &aio_ring_fops, ctx, O_RDWR);
+ file = aio_private_file(ctx, nr_pages);
if (IS_ERR(file)) {
ctx->aio_ring_file = NULL;
return -EAGAIN;
}

- file->f_inode->i_mapping->a_ops = &aio_ctx_aops;
- file->f_inode->i_mapping->private_data = ctx;
- file->f_inode->i_size = PAGE_SIZE * (loff_t)nr_pages;
-
for (i = 0; i < nr_pages; i++) {
struct page *page;
page = find_or_create_page(file->f_inode->i_mapping,