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Commit bbb1e54d authored by Miklos Szeredi's avatar Miklos Szeredi
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ovl: split super.c 

fs/overlayfs/super.c is the biggest of the overlayfs source files and it
contains various utility functions as well as the rather complicated lookup
code.  Split these parts out to separate files.

Before:

 1446 fs/overlayfs/super.c

After:

  919 fs/overlayfs/super.c
  267 fs/overlayfs/namei.c
  235 fs/overlayfs/util.c
   51 fs/overlayfs/ovl_entry.h
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 2b8c30e9
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Showing with 572 additions and 546 deletions
fs/overlayfs/Makefile
View file @ bbb1e54d
...@@ -4,4 +4,4 @@ ...@@ -4,4 +4,4 @@
obj-$(CONFIG_OVERLAY_FS) += overlay.o obj-$(CONFIG_OVERLAY_FS) += overlay.o
overlay-objs := super.o inode.o dir.o readdir.o copy_up.o overlay-objs := super.o namei.o util.o inode.o dir.o readdir.o copy_up.o
fs/overlayfs/namei.c 0 → 100644
View file @ bbb1e54d
/*
* Copyright (C) 2011 Novell Inc.
* Copyright (C) 2016 Red Hat, Inc.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*/
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/xattr.h>
#include "overlayfs.h"
#include "ovl_entry.h"
static struct dentry *ovl_lookup_real(struct dentry *dir,
const struct qstr *name)
{
struct dentry *dentry;
dentry = lookup_one_len_unlocked(name->name, dir, name->len);
if (IS_ERR(dentry)) {
if (PTR_ERR(dentry) == -ENOENT)
dentry = NULL;
} else if (!dentry->d_inode) {
dput(dentry);
dentry = NULL;
} else if (ovl_dentry_weird(dentry)) {
dput(dentry);
/* Don't support traversing automounts and other weirdness */
dentry = ERR_PTR(-EREMOTE);
}
return dentry;
}
static bool ovl_is_opaquedir(struct dentry *dentry)
{
int res;
char val;
if (!d_is_dir(dentry))
return false;
res = vfs_getxattr(dentry, OVL_XATTR_OPAQUE, &val, 1);
if (res == 1 && val == 'y')
return true;
return false;
}
/*
* Returns next layer in stack starting from top.
* Returns -1 if this is the last layer.
*/
int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
{
struct ovl_entry *oe = dentry->d_fsdata;
BUG_ON(idx < 0);
if (idx == 0) {
ovl_path_upper(dentry, path);
if (path->dentry)
return oe->numlower ? 1 : -1;
idx++;
}
BUG_ON(idx > oe->numlower);
*path = oe->lowerstack[idx - 1];
return (idx < oe->numlower) ? idx + 1 : -1;
}
struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
struct ovl_entry *oe;
const struct cred *old_cred;
struct ovl_entry *poe = dentry->d_parent->d_fsdata;
struct path *stack = NULL;
struct dentry *upperdir, *upperdentry = NULL;
unsigned int ctr = 0;
struct inode *inode = NULL;
bool upperopaque = false;
bool stop = false;
bool isdir = false;
struct dentry *this;
unsigned int i;
int err;
old_cred = ovl_override_creds(dentry->d_sb);
upperdir = ovl_upperdentry_dereference(poe);
if (upperdir) {
this = ovl_lookup_real(upperdir, &dentry->d_name);
err = PTR_ERR(this);
if (IS_ERR(this))
goto out;
if (this) {
if (unlikely(ovl_dentry_remote(this))) {
dput(this);
err = -EREMOTE;
goto out;
}
if (ovl_is_whiteout(this)) {
dput(this);
this = NULL;
stop = upperopaque = true;
} else if (!d_is_dir(this)) {
stop = true;
} else {
isdir = true;
if (poe->numlower && ovl_is_opaquedir(this))
stop = upperopaque = true;
}
}
upperdentry = this;
}
if (!stop && poe->numlower) {
err = -ENOMEM;
stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL);
if (!stack)
goto out_put_upper;
}
for (i = 0; !stop && i < poe->numlower; i++) {
struct path lowerpath = poe->lowerstack[i];
this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name);
err = PTR_ERR(this);
if (IS_ERR(this)) {
/*
* If it's positive, then treat ENAMETOOLONG as ENOENT.
*/
if (err == -ENAMETOOLONG && (upperdentry || ctr))
continue;
goto out_put;
}
if (!this)
continue;
if (ovl_is_whiteout(this)) {
dput(this);
break;
}
/*
* If this is a non-directory then stop here.
*/
if (!d_is_dir(this)) {
if (isdir) {
dput(this);
break;
}
stop = true;
} else {
/*
* Only makes sense to check opaque dir if this is not
* the lowermost layer.
*/
if (i < poe->numlower - 1 && ovl_is_opaquedir(this))
stop = true;
}
stack[ctr].dentry = this;
stack[ctr].mnt = lowerpath.mnt;
ctr++;
}
oe = ovl_alloc_entry(ctr);
err = -ENOMEM;
if (!oe)
goto out_put;
if (upperdentry || ctr) {
struct dentry *realdentry;
struct inode *realinode;
realdentry = upperdentry ? upperdentry : stack[0].dentry;
realinode = d_inode(realdentry);
err = -ENOMEM;
if (upperdentry && !d_is_dir(upperdentry)) {
inode = ovl_get_inode(dentry->d_sb, realinode);
} else {
inode = ovl_new_inode(dentry->d_sb, realinode->i_mode,
realinode->i_rdev);
if (inode)
ovl_inode_init(inode, realinode, !!upperdentry);
}
if (!inode)
goto out_free_oe;
ovl_copyattr(realdentry->d_inode, inode);
}
revert_creds(old_cred);
oe->opaque = upperopaque;
oe->__upperdentry = upperdentry;
memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
kfree(stack);
dentry->d_fsdata = oe;
d_add(dentry, inode);
return NULL;
out_free_oe:
kfree(oe);
out_put:
for (i = 0; i < ctr; i++)
dput(stack[i].dentry);
kfree(stack);
out_put_upper:
dput(upperdentry);
out:
revert_creds(old_cred);
return ERR_PTR(err);
}
bool ovl_lower_positive(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
struct ovl_entry *poe = dentry->d_parent->d_fsdata;
const struct qstr *name = &dentry->d_name;
unsigned int i;
bool positive = false;
bool done = false;
/*
* If dentry is negative, then lower is positive iff this is a
* whiteout.
*/
if (!dentry->d_inode)
return oe->opaque;
/* Negative upper -> positive lower */
if (!oe->__upperdentry)
return true;
/* Positive upper -> have to look up lower to see whether it exists */
for (i = 0; !done && !positive && i < poe->numlower; i++) {
struct dentry *this;
struct dentry *lowerdir = poe->lowerstack[i].dentry;
this = lookup_one_len_unlocked(name->name, lowerdir,
name->len);
if (IS_ERR(this)) {
switch (PTR_ERR(this)) {
case -ENOENT:
case -ENAMETOOLONG:
break;
default:
/*
* Assume something is there, we just couldn't
* access it.
*/
positive = true;
break;
}
} else {
if (this->d_inode) {
positive = !ovl_is_whiteout(this);
done = true;
}
dput(this);
}
}
return positive;
}
fs/overlayfs/overlayfs.h
View file @ bbb1e54d
...@@ -9,8 +9,6 @@ ...@@ -9,8 +9,6 @@
#include <linux/kernel.h> #include <linux/kernel.h>
struct ovl_entry;
enum ovl_path_type { enum ovl_path_type {
__OVL_PATH_UPPER = (1 << 0), __OVL_PATH_UPPER = (1 << 0),
__OVL_PATH_MERGE = (1 << 1), __OVL_PATH_MERGE = (1 << 1),
...@@ -138,37 +136,39 @@ static inline struct inode *ovl_inode_real(struct inode *inode, bool *is_upper) ...@@ -138,37 +136,39 @@ static inline struct inode *ovl_inode_real(struct inode *inode, bool *is_upper)
return (struct inode *) (x & ~OVL_ISUPPER_MASK); return (struct inode *) (x & ~OVL_ISUPPER_MASK);
} }
/* util.c */
int ovl_want_write(struct dentry *dentry);
void ovl_drop_write(struct dentry *dentry);
struct dentry *ovl_workdir(struct dentry *dentry);
const struct cred *ovl_override_creds(struct super_block *sb);
struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
bool ovl_dentry_remote(struct dentry *dentry);
bool ovl_dentry_weird(struct dentry *dentry);
enum ovl_path_type ovl_path_type(struct dentry *dentry); enum ovl_path_type ovl_path_type(struct dentry *dentry);
u64 ovl_dentry_version_get(struct dentry *dentry);
void ovl_dentry_version_inc(struct dentry *dentry);
void ovl_path_upper(struct dentry *dentry, struct path *path); void ovl_path_upper(struct dentry *dentry, struct path *path);
void ovl_path_lower(struct dentry *dentry, struct path *path); void ovl_path_lower(struct dentry *dentry, struct path *path);
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path); enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
struct dentry *ovl_dentry_upper(struct dentry *dentry); struct dentry *ovl_dentry_upper(struct dentry *dentry);
struct dentry *ovl_dentry_lower(struct dentry *dentry); struct dentry *ovl_dentry_lower(struct dentry *dentry);
struct dentry *ovl_dentry_real(struct dentry *dentry); struct dentry *ovl_dentry_real(struct dentry *dentry);
struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode,
bool is_upper);
struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry); struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry);
void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache); void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache);
struct dentry *ovl_workdir(struct dentry *dentry);
int ovl_want_write(struct dentry *dentry);
void ovl_drop_write(struct dentry *dentry);
bool ovl_dentry_is_opaque(struct dentry *dentry); bool ovl_dentry_is_opaque(struct dentry *dentry);
bool ovl_lower_positive(struct dentry *dentry);
bool ovl_dentry_is_whiteout(struct dentry *dentry); bool ovl_dentry_is_whiteout(struct dentry *dentry);
void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque); void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque);
bool ovl_is_whiteout(struct dentry *dentry);
const struct cred *ovl_override_creds(struct super_block *sb);
void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry); void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry);
void ovl_inode_init(struct inode *inode, struct inode *realinode,
bool is_upper);
void ovl_inode_update(struct inode *inode, struct inode *upperinode); void ovl_inode_update(struct inode *inode, struct inode *upperinode);
struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, void ovl_dentry_version_inc(struct dentry *dentry);
unsigned int flags); u64 ovl_dentry_version_get(struct dentry *dentry);
bool ovl_is_whiteout(struct dentry *dentry);
struct file *ovl_path_open(struct path *path, int flags); struct file *ovl_path_open(struct path *path, int flags);
struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry, /* namei.c */
struct kstat *stat, const char *link); int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags);
bool ovl_lower_positive(struct dentry *dentry);
/* readdir.c */ /* readdir.c */
extern const struct file_operations ovl_dir_operations; extern const struct file_operations ovl_dir_operations;
......
fs/overlayfs/ovl_entry.h 0 → 100644
View file @ bbb1e54d
/*
*
* Copyright (C) 2011 Novell Inc.
* Copyright (C) 2016 Red Hat, Inc.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*/
struct ovl_config {
char *lowerdir;
char *upperdir;
char *workdir;
bool default_permissions;
};
/* private information held for overlayfs's superblock */
struct ovl_fs {
struct vfsmount *upper_mnt;
unsigned numlower;
struct vfsmount **lower_mnt;
struct dentry *workdir;
long lower_namelen;
/* pathnames of lower and upper dirs, for show_options */
struct ovl_config config;
/* creds of process who forced instantiation of super block */
const struct cred *creator_cred;
};
/* private information held for every overlayfs dentry */
struct ovl_entry {
struct dentry *__upperdentry;
struct ovl_dir_cache *cache;
union {
struct {
u64 version;
bool opaque;
};
struct rcu_head rcu;
};
unsigned numlower;
struct path lowerstack[];
};
struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
static inline struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
{
return lockless_dereference(oe->__upperdentry);
}
fs/overlayfs/super.c
View file @ bbb1e54d
...@@ -9,283 +9,25 @@ ...@@ -9,283 +9,25 @@
#include <linux/fs.h> #include <linux/fs.h>
#include <linux/namei.h> #include <linux/namei.h>
#include <linux/pagemap.h>
#include <linux/xattr.h> #include <linux/xattr.h>
#include <linux/security.h>
#include <linux/mount.h> #include <linux/mount.h>
#include <linux/slab.h>
#include <linux/parser.h> #include <linux/parser.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/sched.h>
#include <linux/statfs.h> #include <linux/statfs.h>
#include <linux/seq_file.h> #include <linux/seq_file.h>
#include <linux/posix_acl_xattr.h> #include <linux/posix_acl_xattr.h>
#include "overlayfs.h" #include "overlayfs.h"
#include "ovl_entry.h"
MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
MODULE_DESCRIPTION("Overlay filesystem"); MODULE_DESCRIPTION("Overlay filesystem");
MODULE_LICENSE("GPL"); MODULE_LICENSE("GPL");
struct ovl_config {
char *lowerdir;
char *upperdir;
char *workdir;
bool default_permissions;
};
/* private information held for overlayfs's superblock */
struct ovl_fs {
struct vfsmount *upper_mnt;
unsigned numlower;
struct vfsmount **lower_mnt;
struct dentry *workdir;
long lower_namelen;
/* pathnames of lower and upper dirs, for show_options */
struct ovl_config config;
/* creds of process who forced instantiation of super block */
const struct cred *creator_cred;
};
struct ovl_dir_cache; struct ovl_dir_cache;
/* private information held for every overlayfs dentry */
struct ovl_entry {
struct dentry *__upperdentry;
struct ovl_dir_cache *cache;
union {
struct {
u64 version;
bool opaque;
};
struct rcu_head rcu;
};
unsigned numlower;
struct path lowerstack[];
};
#define OVL_MAX_STACK 500 #define OVL_MAX_STACK 500
static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe)
{
return oe->numlower ? oe->lowerstack[0].dentry : NULL;
}
enum ovl_path_type ovl_path_type(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
enum ovl_path_type type = 0;
if (oe->__upperdentry) {
type = __OVL_PATH_UPPER;
/*
* Non-dir dentry can hold lower dentry from previous
* location.
*/
if (oe->numlower && d_is_dir(dentry))
type |= __OVL_PATH_MERGE;
} else {
if (oe->numlower > 1)
type |= __OVL_PATH_MERGE;
}
return type;
}
static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
{
return lockless_dereference(oe->__upperdentry);
}
void ovl_path_upper(struct dentry *dentry, struct path *path)
{
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
struct ovl_entry *oe = dentry->d_fsdata;
path->mnt = ofs->upper_mnt;
path->dentry = ovl_upperdentry_dereference(oe);
}
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
{
enum ovl_path_type type = ovl_path_type(dentry);
if (!OVL_TYPE_UPPER(type))
ovl_path_lower(dentry, path);
else
ovl_path_upper(dentry, path);
return type;
}
struct dentry *ovl_dentry_upper(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
return ovl_upperdentry_dereference(oe);
}
struct dentry *ovl_dentry_lower(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
return __ovl_dentry_lower(oe);
}
struct dentry *ovl_dentry_real(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
struct dentry *realdentry;
realdentry = ovl_upperdentry_dereference(oe);
if (!realdentry)
realdentry = __ovl_dentry_lower(oe);
return realdentry;
}
static void ovl_inode_init(struct inode *inode, struct inode *realinode,
bool is_upper)
{
WRITE_ONCE(inode->i_private, (unsigned long) realinode |
(is_upper ? OVL_ISUPPER_MASK : 0));
}
struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode,
bool is_upper)
{
if (is_upper) {
struct ovl_fs *ofs = inode->i_sb->s_fs_info;
return ofs->upper_mnt;
} else {
return oe->numlower ? oe->lowerstack[0].mnt : NULL;
}
}
struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
return oe->cache;
}
void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
{
struct ovl_entry *oe = dentry->d_fsdata;
oe->cache = cache;
}
void ovl_path_lower(struct dentry *dentry, struct path *path)
{
struct ovl_entry *oe = dentry->d_fsdata;
*path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL };
}
int ovl_want_write(struct dentry *dentry)
{
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
return mnt_want_write(ofs->upper_mnt);
}
void ovl_drop_write(struct dentry *dentry)
{
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
mnt_drop_write(ofs->upper_mnt);
}
struct dentry *ovl_workdir(struct dentry *dentry)
{
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
return ofs->workdir;
}
bool ovl_dentry_is_opaque(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
return oe->opaque;
}
bool ovl_dentry_is_whiteout(struct dentry *dentry)
{
return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
}
void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque)
{
struct ovl_entry *oe = dentry->d_fsdata;
oe->opaque = opaque;
}
void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
WARN_ON(!inode_is_locked(upperdentry->d_parent->d_inode));
WARN_ON(oe->__upperdentry);
/*
* Make sure upperdentry is consistent before making it visible to
* ovl_upperdentry_dereference().
*/
smp_wmb();
oe->__upperdentry = upperdentry;
}
void ovl_inode_update(struct inode *inode, struct inode *upperinode)
{
WARN_ON(!upperinode);
WARN_ON(!inode_unhashed(inode));
WRITE_ONCE(inode->i_private,
(unsigned long) upperinode | OVL_ISUPPER_MASK);
if (!S_ISDIR(upperinode->i_mode))
__insert_inode_hash(inode, (unsigned long) upperinode);
}
void ovl_dentry_version_inc(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
WARN_ON(!inode_is_locked(dentry->d_inode));
oe->version++;
}
u64 ovl_dentry_version_get(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
WARN_ON(!inode_is_locked(dentry->d_inode));
return oe->version;
}
bool ovl_is_whiteout(struct dentry *dentry)
{
struct inode *inode = dentry->d_inode;
return inode && IS_WHITEOUT(inode);
}
const struct cred *ovl_override_creds(struct super_block *sb)
{
struct ovl_fs *ofs = sb->s_fs_info;
return override_creds(ofs->creator_cred);
}
static bool ovl_is_opaquedir(struct dentry *dentry)
{
int res;
char val;
if (!d_is_dir(dentry))
return false;
res = vfs_getxattr(dentry, OVL_XATTR_OPAQUE, &val, 1);
if (res == 1 && val == 'y')
return true;
return false;
}
static void ovl_dentry_release(struct dentry *dentry) static void ovl_dentry_release(struct dentry *dentry)
{ {
...@@ -395,275 +137,6 @@ static const struct dentry_operations ovl_reval_dentry_operations = { ...@@ -395,275 +137,6 @@ static const struct dentry_operations ovl_reval_dentry_operations = {
.d_weak_revalidate = ovl_dentry_weak_revalidate, .d_weak_revalidate = ovl_dentry_weak_revalidate,
}; };
static struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
{
size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
if (oe)
oe->numlower = numlower;
return oe;
}
static bool ovl_dentry_remote(struct dentry *dentry)
{
return dentry->d_flags &
(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE |
DCACHE_OP_REAL);
}
static bool ovl_dentry_weird(struct dentry *dentry)
{
return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
DCACHE_MANAGE_TRANSIT |
DCACHE_OP_HASH |
DCACHE_OP_COMPARE);
}
static inline struct dentry *ovl_lookup_real(struct dentry *dir,
const struct qstr *name)
{
struct dentry *dentry;
dentry = lookup_one_len_unlocked(name->name, dir, name->len);
if (IS_ERR(dentry)) {
if (PTR_ERR(dentry) == -ENOENT)
dentry = NULL;
} else if (!dentry->d_inode) {
dput(dentry);
dentry = NULL;
} else if (ovl_dentry_weird(dentry)) {
dput(dentry);
/* Don't support traversing automounts and other weirdness */
dentry = ERR_PTR(-EREMOTE);
}
return dentry;
}
/*
* Returns next layer in stack starting from top.
* Returns -1 if this is the last layer.
*/
int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
{
struct ovl_entry *oe = dentry->d_fsdata;
BUG_ON(idx < 0);
if (idx == 0) {
ovl_path_upper(dentry, path);
if (path->dentry)
return oe->numlower ? 1 : -1;
idx++;
}
BUG_ON(idx > oe->numlower);
*path = oe->lowerstack[idx - 1];
return (idx < oe->numlower) ? idx + 1 : -1;
}
struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
struct ovl_entry *oe;
const struct cred *old_cred;
struct ovl_entry *poe = dentry->d_parent->d_fsdata;
struct path *stack = NULL;
struct dentry *upperdir, *upperdentry = NULL;
unsigned int ctr = 0;
struct inode *inode = NULL;
bool upperopaque = false;
bool stop = false;
bool isdir = false;
struct dentry *this;
unsigned int i;
int err;
old_cred = ovl_override_creds(dentry->d_sb);
upperdir = ovl_upperdentry_dereference(poe);
if (upperdir) {
this = ovl_lookup_real(upperdir, &dentry->d_name);
err = PTR_ERR(this);
if (IS_ERR(this))
goto out;
if (this) {
if (unlikely(ovl_dentry_remote(this))) {
dput(this);
err = -EREMOTE;
goto out;
}
if (ovl_is_whiteout(this)) {
dput(this);
this = NULL;
stop = upperopaque = true;
} else if (!d_is_dir(this)) {
stop = true;
} else {
isdir = true;
if (poe->numlower && ovl_is_opaquedir(this))
stop = upperopaque = true;
}
}
upperdentry = this;
}
if (!stop && poe->numlower) {
err = -ENOMEM;
stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL);
if (!stack)
goto out_put_upper;
}
for (i = 0; !stop && i < poe->numlower; i++) {
struct path lowerpath = poe->lowerstack[i];
this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name);
err = PTR_ERR(this);
if (IS_ERR(this)) {
/*
* If it's positive, then treat ENAMETOOLONG as ENOENT.
*/
if (err == -ENAMETOOLONG && (upperdentry || ctr))
continue;
goto out_put;
}
if (!this)
continue;
if (ovl_is_whiteout(this)) {
dput(this);
break;
}
/*
* If this is a non-directory then stop here.
*/
if (!d_is_dir(this)) {
if (isdir) {
dput(this);
break;
}
stop = true;
} else {
/*
* Only makes sense to check opaque dir if this is not
* the lowermost layer.
*/
if (i < poe->numlower - 1 && ovl_is_opaquedir(this))
stop = true;
}
stack[ctr].dentry = this;
stack[ctr].mnt = lowerpath.mnt;
ctr++;
}
oe = ovl_alloc_entry(ctr);
err = -ENOMEM;
if (!oe)
goto out_put;
if (upperdentry || ctr) {
struct dentry *realdentry;
struct inode *realinode;
realdentry = upperdentry ? upperdentry : stack[0].dentry;
realinode = d_inode(realdentry);
err = -ENOMEM;
if (upperdentry && !d_is_dir(upperdentry)) {
inode = ovl_get_inode(dentry->d_sb, realinode);
} else {
inode = ovl_new_inode(dentry->d_sb, realinode->i_mode,
realinode->i_rdev);
if (inode)
ovl_inode_init(inode, realinode, !!upperdentry);
}
if (!inode)
goto out_free_oe;
ovl_copyattr(realdentry->d_inode, inode);
}
revert_creds(old_cred);
oe->opaque = upperopaque;
oe->__upperdentry = upperdentry;
memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
kfree(stack);
dentry->d_fsdata = oe;
d_add(dentry, inode);
return NULL;
out_free_oe:
kfree(oe);
out_put:
for (i = 0; i < ctr; i++)
dput(stack[i].dentry);
kfree(stack);
out_put_upper:
dput(upperdentry);
out:
revert_creds(old_cred);
return ERR_PTR(err);
}
bool ovl_lower_positive(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
struct ovl_entry *poe = dentry->d_parent->d_fsdata;
const struct qstr *name = &dentry->d_name;
unsigned int i;
bool positive = false;
bool done = false;
/*
* If dentry is negative, then lower is positive iff this is a
* whiteout.
*/
if (!dentry->d_inode)
return oe->opaque;
/* Negative upper -> positive lower */
if (!oe->__upperdentry)
return true;
/* Positive upper -> have to look up lower to see whether it exists */
for (i = 0; !done && !positive && i < poe->numlower; i++) {
struct dentry *this;
struct dentry *lowerdir = poe->lowerstack[i].dentry;
this = lookup_one_len_unlocked(name->name, lowerdir,
name->len);
if (IS_ERR(this)) {
switch (PTR_ERR(this)) {
case -ENOENT:
case -ENAMETOOLONG:
break;
default:
/*
* Assume something is there, we just couldn't
* access it.
*/
positive = true;
break;
}
} else {
if (this->d_inode) {
positive = !ovl_is_whiteout(this);
done = true;
}
dput(this);
}
}
return positive;
}
struct file *ovl_path_open(struct path *path, int flags)
{
return dentry_open(path, flags | O_NOATIME, current_cred());
}
static void ovl_put_super(struct super_block *sb) static void ovl_put_super(struct super_block *sb)
{ {
struct ovl_fs *ufs = sb->s_fs_info; struct ovl_fs *ufs = sb->s_fs_info;
......
fs/overlayfs/util.c 0 → 100644
View file @ bbb1e54d
/*
* Copyright (C) 2011 Novell Inc.
* Copyright (C) 2016 Red Hat, Inc.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*/
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/slab.h>
#include <linux/xattr.h>
#include "overlayfs.h"
#include "ovl_entry.h"
int ovl_want_write(struct dentry *dentry)
{
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
return mnt_want_write(ofs->upper_mnt);
}
void ovl_drop_write(struct dentry *dentry)
{
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
mnt_drop_write(ofs->upper_mnt);
}
struct dentry *ovl_workdir(struct dentry *dentry)
{
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
return ofs->workdir;
}
const struct cred *ovl_override_creds(struct super_block *sb)
{
struct ovl_fs *ofs = sb->s_fs_info;
return override_creds(ofs->creator_cred);
}
struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
{
size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
if (oe)
oe->numlower = numlower;
return oe;
}
bool ovl_dentry_remote(struct dentry *dentry)
{
return dentry->d_flags &
(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE |
DCACHE_OP_REAL);
}
bool ovl_dentry_weird(struct dentry *dentry)
{
return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
DCACHE_MANAGE_TRANSIT |
DCACHE_OP_HASH |
DCACHE_OP_COMPARE);
}
enum ovl_path_type ovl_path_type(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
enum ovl_path_type type = 0;
if (oe->__upperdentry) {
type = __OVL_PATH_UPPER;
/*
* Non-dir dentry can hold lower dentry from previous
* location.
*/
if (oe->numlower && d_is_dir(dentry))
type |= __OVL_PATH_MERGE;
} else {
if (oe->numlower > 1)
type |= __OVL_PATH_MERGE;
}
return type;
}
void ovl_path_upper(struct dentry *dentry, struct path *path)
{
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
struct ovl_entry *oe = dentry->d_fsdata;
path->mnt = ofs->upper_mnt;
path->dentry = ovl_upperdentry_dereference(oe);
}
void ovl_path_lower(struct dentry *dentry, struct path *path)
{
struct ovl_entry *oe = dentry->d_fsdata;
*path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL };
}
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
{
enum ovl_path_type type = ovl_path_type(dentry);
if (!OVL_TYPE_UPPER(type))
ovl_path_lower(dentry, path);
else
ovl_path_upper(dentry, path);
return type;
}
struct dentry *ovl_dentry_upper(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
return ovl_upperdentry_dereference(oe);
}
static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe)
{
return oe->numlower ? oe->lowerstack[0].dentry : NULL;
}
struct dentry *ovl_dentry_lower(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
return __ovl_dentry_lower(oe);
}
struct dentry *ovl_dentry_real(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
struct dentry *realdentry;
realdentry = ovl_upperdentry_dereference(oe);
if (!realdentry)
realdentry = __ovl_dentry_lower(oe);
return realdentry;
}
struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
return oe->cache;
}
void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
{
struct ovl_entry *oe = dentry->d_fsdata;
oe->cache = cache;
}
bool ovl_dentry_is_opaque(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
return oe->opaque;
}
bool ovl_dentry_is_whiteout(struct dentry *dentry)
{
return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
}
void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque)
{
struct ovl_entry *oe = dentry->d_fsdata;
oe->opaque = opaque;
}
void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
WARN_ON(!inode_is_locked(upperdentry->d_parent->d_inode));
WARN_ON(oe->__upperdentry);
/*
* Make sure upperdentry is consistent before making it visible to
* ovl_upperdentry_dereference().
*/
smp_wmb();
oe->__upperdentry = upperdentry;
}
void ovl_inode_init(struct inode *inode, struct inode *realinode, bool is_upper)
{
WRITE_ONCE(inode->i_private, (unsigned long) realinode |
(is_upper ? OVL_ISUPPER_MASK : 0));
}
void ovl_inode_update(struct inode *inode, struct inode *upperinode)
{
WARN_ON(!upperinode);
WARN_ON(!inode_unhashed(inode));
WRITE_ONCE(inode->i_private,
(unsigned long) upperinode | OVL_ISUPPER_MASK);
if (!S_ISDIR(upperinode->i_mode))
__insert_inode_hash(inode, (unsigned long) upperinode);
}
void ovl_dentry_version_inc(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
WARN_ON(!inode_is_locked(dentry->d_inode));
oe->version++;
}
u64 ovl_dentry_version_get(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
WARN_ON(!inode_is_locked(dentry->d_inode));
return oe->version;
}
bool ovl_is_whiteout(struct dentry *dentry)
{
struct inode *inode = dentry->d_inode;
return inode && IS_WHITEOUT(inode);
}
struct file *ovl_path_open(struct path *path, int flags)
{
return dentry_open(path, flags | O_NOATIME, current_cred());
}
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