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mirror_zfs/include/linux/vfs_compat.h
Seth Forshee 3f729907c8 Allow mounting datasets more than once 
Currently mounting an already mounted zfs dataset results in an
error, whereas it is typically allowed with other filesystems.
This causes some bad interactions with mount namespaces. Take
this sequence for example:

- Create a dataset
- Create a snapshot of the dataset
- Create a clone of the snapshot
- Create a new mount namespace
- Rename the original dataset

The rename results in unmounting and remounting the clone in the
original mount namespace, however the remount fails because the
dataset is still mounted in the new mount namespace. (Note that
this means the mount in the new mount namespace is never being
unmounted, so perhaps the unmount/remount of the clone isn't
actually necessary.)

The problem here is a result of the way mounting is implemented
in the kernel module. Since it is not mounting block devices it
uses mount_nodev() instead of the usual mount_bdev(). However,
mount_nodev() is written for filesystems for which each mount is
a new instance (i.e. a new super block), and zfs should be able
to detect when a mount request can be satisfied using an existing
super block.

Change zpl_mount() to call sget() directly with it's own test
callback. Passing the objset_t object as the fs data allows
checking if a superblock already exists for the dataset, and in
that case we just need to return a new reference for the sb's
root dentry.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tom Caputi <tcaputi@datto.com>
Signed-off-by: Alek Pinchuk <apinchuk@datto.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Closes #5796
Closes #7207
2018-05-07 17:19:57 -07:00

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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (C) 2011 Lawrence Livermore National Security, LLC.
* Copyright (C) 2015 Jörg Thalheim.
*/
#ifndef _ZFS_VFS_H
#define _ZFS_VFS_H
#include <sys/taskq.h>
#include <sys/cred.h>
#include <linux/backing-dev.h>
/*
* 2.6.28 API change,
* Added insert_inode_locked() helper function, prior to this most callers
* used insert_inode_hash(). The older method doesn't check for collisions
* in the inode_hashtable but it still acceptible for use.
*/
#ifndef HAVE_INSERT_INODE_LOCKED
static inline int
insert_inode_locked(struct inode *ip)
{
insert_inode_hash(ip);
return (0);
}
#endif /* HAVE_INSERT_INODE_LOCKED */
/*
* 2.6.35 API change,
* Add truncate_setsize() if it is not exported by the Linux kernel.
*
* Truncate the inode and pages associated with the inode. The pages are
* unmapped and removed from cache.
*/
#ifndef HAVE_TRUNCATE_SETSIZE
static inline void
truncate_setsize(struct inode *ip, loff_t new)
{
struct address_space *mapping = ip->i_mapping;
i_size_write(ip, new);
unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
truncate_inode_pages(mapping, new);
unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
}
#endif /* HAVE_TRUNCATE_SETSIZE */
/*
* 2.6.32 - 2.6.33, bdi_setup_and_register() is not available.
* 2.6.34 - 3.19, bdi_setup_and_register() takes 3 arguments.
* 4.0 - 4.11, bdi_setup_and_register() takes 2 arguments.
* 4.12 - x.y, super_setup_bdi_name() new interface.
*/
#if defined(HAVE_SUPER_SETUP_BDI_NAME)
extern atomic_long_t zfs_bdi_seq;
static inline int
zpl_bdi_setup(struct super_block *sb, char *name)
{
return super_setup_bdi_name(sb, "%.28s-%ld", name,
atomic_long_inc_return(&zfs_bdi_seq));
}
static inline void
zpl_bdi_destroy(struct super_block *sb)
{
}
#elif defined(HAVE_2ARGS_BDI_SETUP_AND_REGISTER)
static inline int
zpl_bdi_setup(struct super_block *sb, char *name)
{
struct backing_dev_info *bdi;
int error;
bdi = kmem_zalloc(sizeof (struct backing_dev_info), KM_SLEEP);
error = bdi_setup_and_register(bdi, name);
if (error) {
kmem_free(bdi, sizeof (struct backing_dev_info));
return (error);
}
sb->s_bdi = bdi;
return (0);
}
static inline void
zpl_bdi_destroy(struct super_block *sb)
{
struct backing_dev_info *bdi = sb->s_bdi;
bdi_destroy(bdi);
kmem_free(bdi, sizeof (struct backing_dev_info));
sb->s_bdi = NULL;
}
#elif defined(HAVE_3ARGS_BDI_SETUP_AND_REGISTER)
static inline int
zpl_bdi_setup(struct super_block *sb, char *name)
{
struct backing_dev_info *bdi;
int error;
bdi = kmem_zalloc(sizeof (struct backing_dev_info), KM_SLEEP);
error = bdi_setup_and_register(bdi, name, BDI_CAP_MAP_COPY);
if (error) {
kmem_free(sb->s_bdi, sizeof (struct backing_dev_info));
return (error);
}
sb->s_bdi = bdi;
return (0);
}
static inline void
zpl_bdi_destroy(struct super_block *sb)
{
struct backing_dev_info *bdi = sb->s_bdi;
bdi_destroy(bdi);
kmem_free(bdi, sizeof (struct backing_dev_info));
sb->s_bdi = NULL;
}
#else
extern atomic_long_t zfs_bdi_seq;
static inline int
zpl_bdi_setup(struct super_block *sb, char *name)
{
struct backing_dev_info *bdi;
int error;
bdi = kmem_zalloc(sizeof (struct backing_dev_info), KM_SLEEP);
bdi->name = name;
bdi->capabilities = BDI_CAP_MAP_COPY;
error = bdi_init(bdi);
if (error) {
kmem_free(bdi, sizeof (struct backing_dev_info));
return (error);
}
error = bdi_register(bdi, NULL, "%.28s-%ld", name,
atomic_long_inc_return(&zfs_bdi_seq));
if (error) {
bdi_destroy(bdi);
kmem_free(bdi, sizeof (struct backing_dev_info));
return (error);
}
sb->s_bdi = bdi;
return (0);
}
static inline void
zpl_bdi_destroy(struct super_block *sb)
{
struct backing_dev_info *bdi = sb->s_bdi;
bdi_destroy(bdi);
kmem_free(bdi, sizeof (struct backing_dev_info));
sb->s_bdi = NULL;
}
#endif
/*
* 4.14 adds SB_* flag definitions, define them to MS_* equivalents
* if not set.
*/
#ifndef SB_RDONLY
#define SB_RDONLY MS_RDONLY
#endif
#ifndef SB_SILENT
#define SB_SILENT MS_SILENT
#endif
#ifndef SB_ACTIVE
#define SB_ACTIVE MS_ACTIVE
#endif
#ifndef SB_POSIXACL
#define SB_POSIXACL MS_POSIXACL
#endif
#ifndef SB_MANDLOCK
#define SB_MANDLOCK MS_MANDLOCK
#endif
/*
* 2.6.38 API change,
* LOOKUP_RCU flag introduced to distinguish rcu-walk from ref-walk cases.
*/
#ifndef LOOKUP_RCU
#define LOOKUP_RCU 0x0
#endif /* LOOKUP_RCU */
/*
* 3.2-rc1 API change,
* Add set_nlink() if it is not exported by the Linux kernel.
*
* i_nlink is read-only in Linux 3.2, but it can be set directly in
* earlier kernels.
*/
#ifndef HAVE_SET_NLINK
static inline void
set_nlink(struct inode *inode, unsigned int nlink)
{
inode->i_nlink = nlink;
}
#endif /* HAVE_SET_NLINK */
/*
* 3.3 API change,
* The VFS .create, .mkdir and .mknod callbacks were updated to take a
* umode_t type rather than an int. To cleanly handle both definitions
* the zpl_umode_t type is introduced and set accordingly.
*/
#ifdef HAVE_MKDIR_UMODE_T
typedef umode_t zpl_umode_t;
#else
typedef int zpl_umode_t;
#endif
/*
* 3.5 API change,
* The clear_inode() function replaces end_writeback() and introduces an
* ordering change regarding when the inode_sync_wait() occurs. See the
* configure check in config/kernel-clear-inode.m4 for full details.
*/
#if defined(HAVE_EVICT_INODE) && !defined(HAVE_CLEAR_INODE)
#define clear_inode(ip) end_writeback(ip)
#endif /* HAVE_EVICT_INODE && !HAVE_CLEAR_INODE */
/*
* 3.6 API change,
* The sget() helper function now takes the mount flags as an argument.
*/
#ifdef HAVE_5ARG_SGET
#define zpl_sget(type, cmp, set, fl, mtd) sget(type, cmp, set, fl, mtd)
#else
#define zpl_sget(type, cmp, set, fl, mtd) sget(type, cmp, set, mtd)
#endif /* HAVE_5ARG_SGET */
#if defined(SEEK_HOLE) && defined(SEEK_DATA) && !defined(HAVE_LSEEK_EXECUTE)
static inline loff_t
lseek_execute(
struct file *filp,
struct inode *inode,
loff_t offset,
loff_t maxsize)
{
if (offset < 0 && !(filp->f_mode & FMODE_UNSIGNED_OFFSET))
return (-EINVAL);
if (offset > maxsize)
return (-EINVAL);
if (offset != filp->f_pos) {
spin_lock(&filp->f_lock);
filp->f_pos = offset;
filp->f_version = 0;
spin_unlock(&filp->f_lock);
}
return (offset);
}
#endif /* SEEK_HOLE && SEEK_DATA && !HAVE_LSEEK_EXECUTE */
#if defined(CONFIG_FS_POSIX_ACL)
/*
* These functions safely approximates the behavior of posix_acl_release()
* which cannot be used because it calls the GPL-only symbol kfree_rcu().
* The in-kernel version, which can access the RCU, frees the ACLs after
* the grace period expires. Because we're unsure how long that grace
* period may be this implementation conservatively delays for 60 seconds.
* This is several orders of magnitude larger than expected grace period.
* At 60 seconds the kernel will also begin issuing RCU stall warnings.
*/
#ifdef refcount_t
#undef refcount_t
#endif
#include <linux/posix_acl.h>
#if defined(HAVE_POSIX_ACL_RELEASE) && !defined(HAVE_POSIX_ACL_RELEASE_GPL_ONLY)
#define zpl_posix_acl_release(arg) posix_acl_release(arg)
#else
void zpl_posix_acl_release_impl(struct posix_acl *);
static inline void
zpl_posix_acl_release(struct posix_acl *acl)
{
if ((acl == NULL) || (acl == ACL_NOT_CACHED))
return;
#ifdef HAVE_ACL_REFCOUNT
if (refcount_dec_and_test(&acl->a_refcount))
zpl_posix_acl_release_impl(acl);
#else
if (atomic_dec_and_test(&acl->a_refcount))
zpl_posix_acl_release_impl(acl);
#endif
}
#endif /* HAVE_POSIX_ACL_RELEASE */
#ifdef HAVE_SET_CACHED_ACL_USABLE
#define zpl_set_cached_acl(ip, ty, n) set_cached_acl(ip, ty, n)
#define zpl_forget_cached_acl(ip, ty) forget_cached_acl(ip, ty)
#else
static inline void
zpl_set_cached_acl(struct inode *ip, int type, struct posix_acl *newer)
{
struct posix_acl *older = NULL;
spin_lock(&ip->i_lock);
if ((newer != ACL_NOT_CACHED) && (newer != NULL))
posix_acl_dup(newer);
switch (type) {
case ACL_TYPE_ACCESS:
older = ip->i_acl;
rcu_assign_pointer(ip->i_acl, newer);
break;
case ACL_TYPE_DEFAULT:
older = ip->i_default_acl;
rcu_assign_pointer(ip->i_default_acl, newer);
break;
}
spin_unlock(&ip->i_lock);
zpl_posix_acl_release(older);
}
static inline void
zpl_forget_cached_acl(struct inode *ip, int type)
{
zpl_set_cached_acl(ip, type, (struct posix_acl *)ACL_NOT_CACHED);
}
#endif /* HAVE_SET_CACHED_ACL_USABLE */
#ifndef HAVE___POSIX_ACL_CHMOD
#ifdef HAVE_POSIX_ACL_CHMOD
#define __posix_acl_chmod(acl, gfp, mode) posix_acl_chmod(acl, gfp, mode)
#define __posix_acl_create(acl, gfp, mode) posix_acl_create(acl, gfp, mode)
#else
static inline int
__posix_acl_chmod(struct posix_acl **acl, int flags, umode_t umode)
{
struct posix_acl *oldacl = *acl;
mode_t mode = umode;
int error;
*acl = posix_acl_clone(*acl, flags);
zpl_posix_acl_release(oldacl);
if (!(*acl))
return (-ENOMEM);
error = posix_acl_chmod_masq(*acl, mode);
if (error) {
zpl_posix_acl_release(*acl);
*acl = NULL;
}
return (error);
}
static inline int
__posix_acl_create(struct posix_acl **acl, int flags, umode_t *umodep)
{
struct posix_acl *oldacl = *acl;
mode_t mode = *umodep;
int error;
*acl = posix_acl_clone(*acl, flags);
zpl_posix_acl_release(oldacl);
if (!(*acl))
return (-ENOMEM);
error = posix_acl_create_masq(*acl, &mode);
*umodep = mode;
if (error < 0) {
zpl_posix_acl_release(*acl);
*acl = NULL;
}
return (error);
}
#endif /* HAVE_POSIX_ACL_CHMOD */
#endif /* HAVE___POSIX_ACL_CHMOD */
#ifdef HAVE_POSIX_ACL_EQUIV_MODE_UMODE_T
typedef umode_t zpl_equivmode_t;
#else
typedef mode_t zpl_equivmode_t;
#endif /* HAVE_POSIX_ACL_EQUIV_MODE_UMODE_T */
/*
* 4.8 API change,
* posix_acl_valid() now must be passed a namespace, the namespace from
* from super block associated with the given inode is used for this purpose.
*/
#ifdef HAVE_POSIX_ACL_VALID_WITH_NS
#define zpl_posix_acl_valid(ip, acl) posix_acl_valid(ip->i_sb->s_user_ns, acl)
#else
#define zpl_posix_acl_valid(ip, acl) posix_acl_valid(acl)
#endif
#define refcount_t zfs_refcount_t
#endif /* CONFIG_FS_POSIX_ACL */
/*
* 2.6.38 API change,
* The is_owner_or_cap() function was renamed to inode_owner_or_capable().
*/
#ifdef HAVE_INODE_OWNER_OR_CAPABLE
#define zpl_inode_owner_or_capable(ip) inode_owner_or_capable(ip)
#else
#define zpl_inode_owner_or_capable(ip) is_owner_or_cap(ip)
#endif /* HAVE_INODE_OWNER_OR_CAPABLE */
/*
* 3.19 API change
* struct access f->f_dentry->d_inode was replaced by accessor function
* file_inode(f)
*/
#ifndef HAVE_FILE_INODE
static inline struct inode *file_inode(const struct file *f)
{
return (f->f_dentry->d_inode);
}
#endif /* HAVE_FILE_INODE */
/*
* 4.1 API change
* struct access file->f_path.dentry was replaced by accessor function
* file_dentry(f)
*/
#ifndef HAVE_FILE_DENTRY
static inline struct dentry *file_dentry(const struct file *f)
{
return (f->f_path.dentry);
}
#endif /* HAVE_FILE_DENTRY */
#ifdef HAVE_KUID_HELPERS
static inline uid_t zfs_uid_read_impl(struct inode *ip)
{
#ifdef HAVE_SUPER_USER_NS
return (from_kuid(ip->i_sb->s_user_ns, ip->i_uid));
#else
return (from_kuid(kcred->user_ns, ip->i_uid));
#endif
}
static inline uid_t zfs_uid_read(struct inode *ip)
{
return (zfs_uid_read_impl(ip));
}
static inline gid_t zfs_gid_read_impl(struct inode *ip)
{
#ifdef HAVE_SUPER_USER_NS
return (from_kgid(ip->i_sb->s_user_ns, ip->i_gid));
#else
return (from_kgid(kcred->user_ns, ip->i_gid));
#endif
}
static inline gid_t zfs_gid_read(struct inode *ip)
{
return (zfs_gid_read_impl(ip));
}
static inline void zfs_uid_write(struct inode *ip, uid_t uid)
{
#ifdef HAVE_SUPER_USER_NS
ip->i_uid = make_kuid(ip->i_sb->s_user_ns, uid);
#else
ip->i_uid = make_kuid(kcred->user_ns, uid);
#endif
}
static inline void zfs_gid_write(struct inode *ip, gid_t gid)
{
#ifdef HAVE_SUPER_USER_NS
ip->i_gid = make_kgid(ip->i_sb->s_user_ns, gid);
#else
ip->i_gid = make_kgid(kcred->user_ns, gid);
#endif
}
#else
static inline uid_t zfs_uid_read(struct inode *ip)
{
return (ip->i_uid);
}
static inline gid_t zfs_gid_read(struct inode *ip)
{
return (ip->i_gid);
}
static inline void zfs_uid_write(struct inode *ip, uid_t uid)
{
ip->i_uid = uid;
}
static inline void zfs_gid_write(struct inode *ip, gid_t gid)
{
ip->i_gid = gid;
}
#endif
/*
* 2.6.38 API change
*/
#ifdef HAVE_FOLLOW_DOWN_ONE
#define zpl_follow_down_one(path) follow_down_one(path)
#define zpl_follow_up(path) follow_up(path)
#else
#define zpl_follow_down_one(path) follow_down(path)
#define zpl_follow_up(path) follow_up(path)
#endif
/*
* 4.9 API change
*/
#ifndef HAVE_SETATTR_PREPARE
static inline int
setattr_prepare(struct dentry *dentry, struct iattr *ia)
{
return (inode_change_ok(dentry->d_inode, ia));
}
#endif
/*
* 4.11 API change
* These macros are defined by kernel 4.11. We define them so that the same
* code builds under kernels < 4.11 and >= 4.11. The macros are set to 0 so
* that it will create obvious failures if they are accidentally used when built
* against a kernel >= 4.11.
*/
#ifndef STATX_BASIC_STATS
#define STATX_BASIC_STATS 0
#endif
#ifndef AT_STATX_SYNC_AS_STAT
#define AT_STATX_SYNC_AS_STAT 0
#endif
/*
* 4.11 API change
* 4.11 takes struct path *, < 4.11 takes vfsmount *
*/
#ifdef HAVE_VFSMOUNT_IOPS_GETATTR
#define ZPL_GETATTR_WRAPPER(func) \
static int \
func(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) \
{ \
struct path path = { .mnt = mnt, .dentry = dentry }; \
return func##_impl(&path, stat, STATX_BASIC_STATS, \
AT_STATX_SYNC_AS_STAT); \
}
#elif defined(HAVE_PATH_IOPS_GETATTR)
#define ZPL_GETATTR_WRAPPER(func) \
static int \
func(const struct path *path, struct kstat *stat, u32 request_mask, \
unsigned int query_flags) \
{ \
return (func##_impl(path, stat, request_mask, query_flags)); \
}
#else
#error
#endif
/*
* 4.9 API change
* Preferred interface to get the current FS time.
*/
#if !defined(HAVE_CURRENT_TIME)
static inline struct timespec
current_time(struct inode *ip)
{
return (timespec_trunc(current_kernel_time(), ip->i_sb->s_time_gran));
}
#endif
/*
* 4.16 API change
* Added iversion interface for managing inode version field.
*/
#ifdef HAVE_INODE_SET_IVERSION
#include <linux/iversion.h>
#else
static inline void
inode_set_iversion(struct inode *ip, u64 val)
{
ip->i_version = val;
}
#endif
#endif /* _ZFS_VFS_H */
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