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mnt: Add filesystem private data to mount points

Browse source 
This starts to add private data associated directly
to mount points. The intent is to give filesystems
a sense of where they have come from, as a means of
letting a filesystem take different actions based on
this information.

Change-Id: Ie769d7b3bb2f5972afe05c1bf16cf88c91647ab2
Signed-off-by: Daniel Rosenberg <drosen@google.com>
This commit is contained in:
Daniel Rosenberg 2016-10-26 15:29:51 -07:00 committed by Artem Borisov
parent 313cdb2651
commit ccbd24c7a0
5 changed files with 43 additions and 1 deletions
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25
fs/namespace.c
View file

@ -482,6 +482,7 @@ int sb_prepare_remount_readonly(struct super_block *sb)
static void free_vfsmnt(struct mount *mnt)
{
kfree(mnt->mnt.data);
kfree(mnt->mnt_devname);
mnt_free_id(mnt);
#ifdef CONFIG_SMP
@ -698,11 +699,21 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void
if (!mnt)
return ERR_PTR(-ENOMEM);
mnt->mnt.data = NULL;
if (type->alloc_mnt_data) {
mnt->mnt.data = type->alloc_mnt_data();
if (!mnt->mnt.data) {
mnt_free_id(mnt);
free_vfsmnt(mnt);
return ERR_PTR(-ENOMEM);
}
}
if (flags & MS_KERNMOUNT)
mnt->mnt.mnt_flags = MNT_INTERNAL;
root = mount_fs(type, flags, name, data);
if (IS_ERR(root)) {
kfree(mnt->mnt.data);
free_vfsmnt(mnt);
return ERR_CAST(root);
}
@ -729,6 +740,13 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
if (!mnt)
return ERR_PTR(-ENOMEM);
if (sb->s_op->clone_mnt_data) {
mnt->mnt.data = sb->s_op->clone_mnt_data(old->mnt.data);
if (!mnt->mnt.data) {
goto out_free;
}
}
if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE))
mnt->mnt_group_id = 0; /* not a peer of original */
else
@ -775,6 +793,7 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
return mnt;
out_free:
kfree(mnt->mnt.data);
free_vfsmnt(mnt);
return ERR_PTR(err);
}
@ -1710,8 +1729,12 @@ static int do_remount(struct path *path, int flags, int mnt_flags,
down_write(&sb->s_umount);
if (flags & MS_BIND)
err = change_mount_flags(path->mnt, flags);
else
else {
err = do_remount_sb(sb, flags, data, 0);
br_write_lock(&vfsmount_lock);
propagate_remount(mnt);
br_write_unlock(&vfsmount_lock);
}
if (!err) {
br_write_lock(&vfsmount_lock);
mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK;

14
fs/pnode.c
View file

@ -354,3 +354,17 @@ int propagate_umount(struct list_head *list)
__propagate_umount(mnt);
return 0;
}
int propagate_remount(struct mount *mnt) {
struct mount *m;
struct super_block *sb = mnt->mnt.mnt_sb;
int ret = 0;
if (sb->s_op->copy_mnt_data) {
for (m = first_slave(mnt); m->mnt_slave.next != &mnt->mnt_slave_list; m = next_slave(m)) {
sb->s_op->copy_mnt_data(m->mnt.data, mnt->mnt.data);
}
}
return ret;
}

1
fs/pnode.h
View file

@ -35,6 +35,7 @@ int propagate_mnt(struct mount *, struct dentry *, struct mount *,
struct list_head *);
int propagate_umount(struct list_head *);
int propagate_mount_busy(struct mount *, int);
int propagate_remount(struct mount *);
void mnt_release_group_id(struct mount *);
int get_dominating_id(struct mount *mnt, const struct path *root);
unsigned int mnt_get_count(struct mount *mnt);

3
include/linux/fs.h
View file

@ -1731,6 +1731,8 @@ struct super_operations {
int (*unfreeze_fs) (struct super_block *);
int (*statfs) (struct dentry *, struct kstatfs *);
int (*remount_fs) (struct super_block *, int *, char *);
void *(*clone_mnt_data) (void *);
void (*copy_mnt_data) (void *, void *);
void (*umount_begin) (struct super_block *);
int (*show_options)(struct seq_file *, struct dentry *);
@ -1886,6 +1888,7 @@ struct file_system_type {
#define FS_RENAME_DOES_D_MOVE 32768 /* FS will handle d_move() during rename() internally. */
struct dentry *(*mount) (struct file_system_type *, int,
const char *, void *);
void *(*alloc_mnt_data) (void);
void (*kill_sb) (struct super_block *);
struct module *owner;
struct file_system_type * next;

1
include/linux/mount.h
View file

@ -53,6 +53,7 @@ struct vfsmount {
struct dentry *mnt_root; /* root of the mounted tree */
struct super_block *mnt_sb; /* pointer to superblock */
int mnt_flags;
void *data;
};
struct file; /* forward dec */