[PATCH 12/20] KVM: Remove kvmfs in favor of the anonymous inodes source

Avi Kivity
2007-07-08T11:54:41Z

kvm uses a pseudo filesystem, kvmfs, to generate inodes, a job that the
new anonymous inodes source does much better.

Cc: Davide Libenzi <davidel-AhlLAIvw+VEjIGhXcJzhZg@public.gmane.org>
Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
---
drivers/kvm/kvm_main.c | 143 ++++--------------------------------------------
fs/anon_inodes.c | 1 +
include/linux/magic.h | 1 -
3 files changed, 12 insertions(+), 133 deletions(-)

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 5603000..26ca90f 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -43,6 +43,7 @@
#include <linux/sched.h>
#include <linux/cpumask.h>
#include <linux/smp.h>
+#include <linux/anon_inodes.h>

#include "x86_emulate.h"
#include "segment_descriptor.h"
@@ -81,8 +82,6 @@ static struct kvm_stats_debugfs_item {

static struct dentry *debugfs_dir;

-struct vfsmount *kvmfs_mnt;
-
#define MAX_IO_MSRS 256

#define CR0_RESEVED_BITS 0xffffffff1ffaffc0ULL
@@ -104,55 +103,6 @@ struct segment_descriptor_64 {
static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl,
unsigned long arg);

-static struct inode *kvmfs_inode(struct file_operations *fops)
-{
- int error = -ENOMEM;
- struct inode *inode = new_inode(kvmfs_mnt->mnt_sb);
-
- if (!inode)
- goto eexit_1;
-
- inode->i_fop = fops;
-
- /*
- * Mark the inode dirty from the very beginning,
- * that way it will never be moved to the dirty
- * list because mark_inode_dirty() will think
- * that it already _is_ on the dirty list.
- */
- inode->i_state = I_DIRTY;
- inode->i_mode = S_IRUSR | S_IWUSR;
- inode->i_uid = current->fsuid;
- inode->i_gid = current->fsgid;
- inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
- return inode;
-
-eexit_1:
- return ERR_PTR(error);
-}
-
-static struct file *kvmfs_file(struct inode *inode, void *private_data)
-{
- struct file *file = get_empty_filp();
-
- if (!file)
- return ERR_PTR(-ENFILE);
-
- file->f_path.mnt = mntget(kvmfs_mnt);
- file->f_path.dentry = d_alloc_anon(inode);
- if (!file->f_path.dentry)
- return ERR_PTR(-ENOMEM);
- file->f_mapping = inode->i_mapping;
-
- file->f_pos = 0;
- file->f_flags = O_RDWR;
- file->f_op = inode->i_fop;
- file->f_mode = FMODE_READ | FMODE_WRITE;
- file->f_version = 0;
- file->private_data = private_data;
- return file;
-}
-
unsigned long segment_base(u16 selector)
{
struct descriptor_table gdt;
@@ -2413,34 +2363,12 @@ static int create_vcpu_fd(struct kvm_vcpu *vcpu)
struct inode *inode;
struct file *file;

+ r = anon_inode_getfd(&fd, &inode, &file,
+ "kvm-vcpu", &kvm_vcpu_fops, vcpu);
+ if (r)
+ return r;
atomic_inc(&vcpu->kvm->filp->f_count);
- inode = kvmfs_inode(&kvm_vcpu_fops);
- if (IS_ERR(inode)) {
- r = PTR_ERR(inode);
- goto out1;
- }
-
- file = kvmfs_file(inode, vcpu);
- if (IS_ERR(file)) {
- r = PTR_ERR(file);
- goto out2;
- }
-
- r = get_unused_fd();
- if (r < 0)
- goto out3;
- fd = r;
- fd_install(fd, file);
-
return fd;
-
-out3:
- fput(file);
-out2:
- iput(inode);
-out1:
- fput(vcpu->kvm->filp);
- return r;
}

/*
@@ -2905,41 +2833,18 @@ static int kvm_dev_ioctl_create_vm(void)
struct file *file;
struct kvm *kvm;

- inode = kvmfs_inode(&kvm_vm_fops);
- if (IS_ERR(inode)) {
- r = PTR_ERR(inode);
- goto out1;
- }
-
kvm = kvm_create_vm();
- if (IS_ERR(kvm)) {
- r = PTR_ERR(kvm);
- goto out2;
+ if (IS_ERR(kvm))
+ return PTR_ERR(kvm);
+ r = anon_inode_getfd(&fd, &inode, &file, "kvm-vm", &kvm_vm_fops, kvm);
+ if (r) {
+ kvm_destroy_vm(kvm);
+ return r;
}

- file = kvmfs_file(inode, kvm);
- if (IS_ERR(file)) {
- r = PTR_ERR(file);
- goto out3;
- }
kvm->filp = file;

- r = get_unused_fd();
- if (r < 0)
- goto out4;
- fd = r;
- fd_install(fd, file);
-
return fd;
-
-out4:
- fput(file);
-out3:
- kvm_destroy_vm(kvm);
-out2:
- iput(inode);
-out1:
- return r;
}

static long kvm_dev_ioctl(struct file *filp,
@@ -3211,18 +3116,6 @@ static struct sys_device kvm_sysdev = {

hpa_t bad_page_address;

-static int kvmfs_get_sb(struct file_system_type *fs_type, int flags,
- const char *dev_name, void *data, struct vfsmount *mnt)
-{
- return get_sb_pseudo(fs_type, "kvm:", NULL, KVMFS_SUPER_MAGIC, mnt);
-}
-
-static struct file_system_type kvm_fs_type = {
- .name = "kvmfs",
- .get_sb = kvmfs_get_sb,
- .kill_sb = kill_anon_super,
-};
-
int kvm_init_arch(struct kvm_arch_ops *ops, struct module *module)
{
int r;
@@ -3307,14 +3200,6 @@ static __init int kvm_init(void)
if (r)
goto out4;

- r = register_filesystem(&kvm_fs_type);
- if (r)
- goto out3;
-
- kvmfs_mnt = kern_mount(&kvm_fs_type);
- r = PTR_ERR(kvmfs_mnt);
- if (IS_ERR(kvmfs_mnt))
- goto out2;
kvm_init_debug();

kvm_init_msr_list();
@@ -3331,10 +3216,6 @@ static __init int kvm_init(void)

out:
kvm_exit_debug();
- mntput(kvmfs_mnt);
-out2:
- unregister_filesystem(&kvm_fs_type);
-out3:
kvm_mmu_module_exit();
out4:
return r;
@@ -3344,8 +3225,6 @@ static __exit void kvm_exit(void)
{
kvm_exit_debug();
__free_page(pfn_to_page(bad_page_address >> PAGE_SHIFT));
- mntput(kvmfs_mnt);
- unregister_filesystem(&kvm_fs_type);
kvm_mmu_module_exit();
}

diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index 40fe3a3..edc6748 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -139,6 +139,7 @@ err_put_filp:
put_filp(file);
return error;
}
+EXPORT_SYMBOL_GPL(anon_inode_getfd);

/*
* A single inode exist for all anon_inode files. Contrary to pipes,
diff --git a/include/linux/magic.h b/include/linux/magic.h
index 9d713c0..36cc20d 100644
--- a/include/linux/magic.h
+++ b/include/linux/magic.h
@@ -13,7 +13,6 @@
#define HPFS_SUPER_MAGIC 0xf995e849
#define ISOFS_SUPER_MAGIC 0x9660
#define JFFS2_SUPER_MAGIC 0x72b6
-#define KVMFS_SUPER_MAGIC 0x19700426
#define ANON_INODE_FS_MAGIC 0x09041934

#define MINIX_SUPER_MAGIC 0x137F /* original minix fs */