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overlayfs update for 4.19 

This contains two new features:
 
  1) Stack file operations: this allows removal of several hacks from the
     VFS, proper interaction of read-only open files with copy-up,
     possibility to implement fs modifying ioctls properly, and others.
 
  2) Metadata only copy-up: when file is on lower layer and only metadata is
     modified (except size) then only copy up the metadata and continue to
     use the data from the lower file.
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Merge tag 'ovl-update-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull overlayfs updates from Miklos Szeredi:
 "This contains two new features:

   - Stack file operations: this allows removal of several hacks from
     the VFS, proper interaction of read-only open files with copy-up,
     possibility to implement fs modifying ioctls properly, and others.

   - Metadata only copy-up: when file is on lower layer and only
     metadata is modified (except size) then only copy up the metadata
     and continue to use the data from the lower file"

* tag 'ovl-update-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: (66 commits)
  ovl: Enable metadata only feature
  ovl: Do not do metacopy only for ioctl modifying file attr
  ovl: Do not do metadata only copy-up for truncate operation
  ovl: add helper to force data copy-up
  ovl: Check redirect on index as well
  ovl: Set redirect on upper inode when it is linked
  ovl: Set redirect on metacopy files upon rename
  ovl: Do not set dentry type ORIGIN for broken hardlinks
  ovl: Add an inode flag OVL_CONST_INO
  ovl: Treat metacopy dentries as type OVL_PATH_MERGE
  ovl: Check redirects for metacopy files
  ovl: Move some dir related ovl_lookup_single() code in else block
  ovl: Do not expose metacopy only dentry from d_real()
  ovl: Open file with data except for the case of fsync
  ovl: Add helper ovl_inode_realdata()
  ovl: Store lower data inode in ovl_inode
  ovl: Fix ovl_getattr() to get number of blocks from lower
  ovl: Add helper ovl_dentry_lowerdata() to get lower data dentry
  ovl: Copy up meta inode data from lowest data inode
  ovl: Modify ovl_lookup() and friends to lookup metacopy dentry
  ...
This commit is contained in:
Linus Torvalds 2018-08-21 18:19:09 -07:00
parent c22fc16d17 989974c804
commit d9a185f8b4
33 changed files with 1624 additions and 600 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
Documentation/filesystems/Locking
View File

@ -21,8 +21,7 @@ prototypes:
char *(*d_dname)((struct dentry *dentry, char *buffer, int buflen);
struct vfsmount *(*d_automount)(struct path *path);
int (*d_manage)(const struct path *, bool);
struct dentry *(*d_real)(struct dentry *, const struct inode *,
unsigned int, unsigned int);
struct dentry *(*d_real)(struct dentry *, const struct inode *);
locking rules:
rename_lock ->d_lock may block rcu-walk

81
Documentation/filesystems/overlayfs.txt
View File

@ -10,10 +10,6 @@ union-filesystems). An overlay-filesystem tries to present a
filesystem which is the result over overlaying one filesystem on top
of the other.
The result will inevitably fail to look exactly like a normal
filesystem for various technical reasons. The expectation is that
many use cases will be able to ignore these differences.
Overlay objects
---------------
@ -266,6 +262,30 @@ rightmost one and going left. In the above example lower1 will be the
top, lower2 the middle and lower3 the bottom layer.
Metadata only copy up
--------------------
When metadata only copy up feature is enabled, overlayfs will only copy
up metadata (as opposed to whole file), when a metadata specific operation
like chown/chmod is performed. Full file will be copied up later when
file is opened for WRITE operation.
In other words, this is delayed data copy up operation and data is copied
up when there is a need to actually modify data.
There are multiple ways to enable/disable this feature. A config option
CONFIG_OVERLAY_FS_METACOPY can be set/unset to enable/disable this feature
by default. Or one can enable/disable it at module load time with module
parameter metacopy=on/off. Lastly, there is also a per mount option
metacopy=on/off to enable/disable this feature per mount.
Do not use metacopy=on with untrusted upper/lower directories. Otherwise
it is possible that an attacker can create a handcrafted file with
appropriate REDIRECT and METACOPY xattrs, and gain access to file on lower
pointed by REDIRECT. This should not be possible on local system as setting
"trusted." xattrs will require CAP_SYS_ADMIN. But it should be possible
for untrusted layers like from a pen drive.
Sharing and copying layers
--------------------------
@ -284,7 +304,7 @@ though it will not result in a crash or deadlock.
Mounting an overlay using an upper layer path, where the upper layer path
was previously used by another mounted overlay in combination with a
different lower layer path, is allowed, unless the "inodes index" feature
is enabled.
or "metadata only copy up" feature is enabled.
With the "inodes index" feature, on the first time mount, an NFS file
handle of the lower layer root directory, along with the UUID of the lower
@ -297,6 +317,10 @@ lower root origin, mount will fail with ESTALE. An overlayfs mount with
does not support NFS export, lower filesystem does not have a valid UUID or
if the upper filesystem does not support extended attributes.
For "metadata only copy up" feature there is no verification mechanism at
mount time. So if same upper is mounted with different set of lower, mount
probably will succeed but expect the unexpected later on. So don't do it.
It is quite a common practice to copy overlay layers to a different
directory tree on the same or different underlying filesystem, and even
to a different machine. With the "inodes index" feature, trying to mount
@ -306,27 +330,40 @@ the copied layers will fail the verification of the lower root file handle.
Non-standard behavior
---------------------
The copy_up operation essentially creates a new, identical file and
moves it over to the old name. Any open files referring to this inode
will access the old data.
Overlayfs can now act as a POSIX compliant filesystem with the following
features turned on:
The new file may be on a different filesystem, so both st_dev and st_ino
of the real file may change. The values of st_dev and st_ino returned by
stat(2) on an overlay object are often not the same as the real file
stat(2) values to prevent the values from changing on copy_up.
1) "redirect_dir"
Unless "xino" feature is enabled, when overlay layers are not all on the
same underlying filesystem, the value of st_dev may be different for two
non-directory objects in the same overlay filesystem and the value of
st_ino for directory objects may be non persistent and could change even
while the overlay filesystem is still mounted.
Enabled with the mount option or module option: "redirect_dir=on" or with
the kernel config option CONFIG_OVERLAY_FS_REDIRECT_DIR=y.
Unless "inode index" feature is enabled, if a file with multiple hard
links is copied up, then this will "break" the link. Changes will not be
propagated to other names referring to the same inode.
If this feature is disabled, then rename(2) on a lower or merged directory
will fail with EXDEV ("Invalid cross-device link").
Unless "redirect_dir" feature is enabled, rename(2) on a lower or merged
directory will fail with EXDEV.
2) "inode index"
Enabled with the mount option or module option "index=on" or with the
kernel config option CONFIG_OVERLAY_FS_INDEX=y.
If this feature is disabled and a file with multiple hard links is copied
up, then this will "break" the link. Changes will not be propagated to
other names referring to the same inode.
3) "xino"
Enabled with the mount option "xino=auto" or "xino=on", with the module
option "xino_auto=on" or with the kernel config option
CONFIG_OVERLAY_FS_XINO_AUTO=y. Also implicitly enabled by using the same
underlying filesystem for all layers making up the overlay.
If this feature is disabled or the underlying filesystem doesn't have
enough free bits in the inode number, then overlayfs will not be able to
guarantee that the values of st_ino and st_dev returned by stat(2) and the
value of d_ino returned by readdir(3) will act like on a normal filesystem.
E.g. the value of st_dev may be different for two objects in the same
overlay filesystem and the value of st_ino for directory objects may not be
persistent and could change even while the overlay filesystem is mounted.
Changes to underlying filesystems

16
Documentation/filesystems/vfs.txt
View File

@ -989,8 +989,7 @@ struct dentry_operations {
char *(*d_dname)(struct dentry *, char *, int);
struct vfsmount *(*d_automount)(struct path *);
int (*d_manage)(const struct path *, bool);
struct dentry *(*d_real)(struct dentry *, const struct inode *,
unsigned int, unsigned int);
struct dentry *(*d_real)(struct dentry *, const struct inode *);
};
d_revalidate: called when the VFS needs to revalidate a dentry. This
@ -1124,22 +1123,15 @@ struct dentry_operations {
dentry being transited from.
d_real: overlay/union type filesystems implement this method to return one of
the underlying dentries hidden by the overlay. It is used in three
the underlying dentries hidden by the overlay. It is used in two
different modes:
Called from open it may need to copy-up the file depending on the
supplied open flags. This mode is selected with a non-zero flags
argument. In this mode the d_real method can return an error.
Called from file_dentry() it returns the real dentry matching the inode
argument. The real dentry may be from a lower layer already copied up,
but still referenced from the file. This mode is selected with a
non-NULL inode argument. This will always succeed.
non-NULL inode argument.
With NULL inode and zero flags the topmost real underlying dentry is
returned. This will always succeed.
This method is never called with both non-NULL inode and non-zero flags.
With NULL inode the topmost real underlying dentry is returned.
Each dentry has a pointer to its parent dentry, as well as a hash list
of child dentries. Child dentries are basically like files in a

5
fs/btrfs/ctree.h
View File

@ -3217,8 +3217,9 @@ void btrfs_get_block_group_info(struct list_head *groups_list,
struct btrfs_ioctl_space_info *space);
void btrfs_update_ioctl_balance_args(struct btrfs_fs_info *fs_info,
struct btrfs_ioctl_balance_args *bargs);
ssize_t btrfs_dedupe_file_range(struct file *src_file, u64 loff, u64 olen,
struct file *dst_file, u64 dst_loff);
int btrfs_dedupe_file_range(struct file *src_file, loff_t src_loff,
struct file *dst_file, loff_t dst_loff,
u64 olen);
/* file.c */
int __init btrfs_auto_defrag_init(void);

11
fs/btrfs/ioctl.c
View File

@ -3592,13 +3592,13 @@ out_unlock:
return ret;
}
ssize_t btrfs_dedupe_file_range(struct file *src_file, u64 loff, u64 olen,
struct file *dst_file, u64 dst_loff)
int btrfs_dedupe_file_range(struct file *src_file, loff_t src_loff,
struct file *dst_file, loff_t dst_loff,
u64 olen)
{
struct inode *src = file_inode(src_file);
struct inode *dst = file_inode(dst_file);
u64 bs = BTRFS_I(src)->root->fs_info->sb->s_blocksize;
ssize_t res;
if (WARN_ON_ONCE(bs < PAGE_SIZE)) {
/*
@ -3609,10 +3609,7 @@ ssize_t btrfs_dedupe_file_range(struct file *src_file, u64 loff, u64 olen,
return -EINVAL;
}
res = btrfs_extent_same(src, loff, olen, dst, dst_loff);
if (res)
return res;
return olen;
return btrfs_extent_same(src, src_loff, olen, dst, dst_loff);
}
static int clone_finish_inode_update(struct btrfs_trans_handle *trans,

79
fs/file_table.c
View File

@ -52,7 +52,8 @@ static void file_free_rcu(struct rcu_head *head)
static inline void file_free(struct file *f)
{
security_file_free(f);
percpu_counter_dec(&nr_files);
if (!(f->f_mode & FMODE_NOACCOUNT))
percpu_counter_dec(&nr_files);
call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
}
@ -91,34 +92,11 @@ int proc_nr_files(struct ctl_table *table, int write,
}
#endif
/* Find an unused file structure and return a pointer to it.
* Returns an error pointer if some error happend e.g. we over file
* structures limit, run out of memory or operation is not permitted.
*
* Be very careful using this. You are responsible for
* getting write access to any mount that you might assign
* to this filp, if it is opened for write. If this is not
* done, you will imbalance int the mount's writer count
* and a warning at __fput() time.
*/
struct file *alloc_empty_file(int flags, const struct cred *cred)
static struct file *__alloc_file(int flags, const struct cred *cred)
{
static long old_max;
struct file *f;
int error;
/*
* Privileged users can go above max_files
*/
if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) {
/*
* percpu_counters are inaccurate. Do an expensive check before
* we go and fail.
*/
if (percpu_counter_sum_positive(&nr_files) >= files_stat.max_files)
goto over;
}
f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL);
if (unlikely(!f))
return ERR_PTR(-ENOMEM);
@ -138,7 +116,41 @@ struct file *alloc_empty_file(int flags, const struct cred *cred)
f->f_flags = flags;
f->f_mode = OPEN_FMODE(flags);
/* f->f_version: 0 */
percpu_counter_inc(&nr_files);
return f;
}
/* Find an unused file structure and return a pointer to it.
* Returns an error pointer if some error happend e.g. we over file
* structures limit, run out of memory or operation is not permitted.
*
* Be very careful using this. You are responsible for
* getting write access to any mount that you might assign
* to this filp, if it is opened for write. If this is not
* done, you will imbalance int the mount's writer count
* and a warning at __fput() time.
*/
struct file *alloc_empty_file(int flags, const struct cred *cred)
{
static long old_max;
struct file *f;
/*
* Privileged users can go above max_files
*/
if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) {
/*
* percpu_counters are inaccurate. Do an expensive check before
* we go and fail.
*/
if (percpu_counter_sum_positive(&nr_files) >= files_stat.max_files)
goto over;
}
f = __alloc_file(flags, cred);
if (!IS_ERR(f))
percpu_counter_inc(&nr_files);
return f;
over:
@ -150,6 +162,21 @@ over:
return ERR_PTR(-ENFILE);
}
/*
* Variant of alloc_empty_file() that doesn't check and modify nr_files.
*
* Should not be used unless there's a very good reason to do so.
*/
struct file *alloc_empty_file_noaccount(int flags, const struct cred *cred)
{
struct file *f = __alloc_file(flags, cred);
if (!IS_ERR(f))
f->f_mode |= FMODE_NOACCOUNT;
return f;
}
/**
* alloc_file - allocate and initialize a 'struct file'
*

46
fs/inode.c
View File

@ -1595,50 +1595,17 @@ sector_t bmap(struct inode *inode, sector_t block)
}
EXPORT_SYMBOL(bmap);
/*
* Update times in overlayed inode from underlying real inode
*/
static void update_ovl_inode_times(struct dentry *dentry, struct inode *inode,
bool rcu)
{
struct dentry *upperdentry;
/*
* Nothing to do if in rcu or if non-overlayfs
*/
if (rcu || likely(!(dentry->d_flags & DCACHE_OP_REAL)))
return;
upperdentry = d_real(dentry, NULL, 0, D_REAL_UPPER);
/*
* If file is on lower then we can't update atime, so no worries about
* stale mtime/ctime.
*/
if (upperdentry) {
struct inode *realinode = d_inode(upperdentry);
if ((!timespec64_equal(&inode->i_mtime, &realinode->i_mtime) ||
!timespec64_equal(&inode->i_ctime, &realinode->i_ctime))) {
inode->i_mtime = realinode->i_mtime;
inode->i_ctime = realinode->i_ctime;
}
}
}
/*
* With relative atime, only update atime if the previous atime is
* earlier than either the ctime or mtime or if at least a day has
* passed since the last atime update.
*/
static int relatime_need_update(const struct path *path, struct inode *inode,
struct timespec now, bool rcu)
static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
struct timespec now)
{
if (!(path->mnt->mnt_flags & MNT_RELATIME))
if (!(mnt->mnt_flags & MNT_RELATIME))
return 1;
update_ovl_inode_times(path->dentry, inode, rcu);
/*
* Is mtime younger than atime? If yes, update atime:
*/
@ -1709,8 +1676,7 @@ static int update_time(struct inode *inode, struct timespec64 *time, int flags)
* This function automatically handles read only file systems and media,
* as well as the "noatime" flag and inode specific "noatime" markers.
*/
bool __atime_needs_update(const struct path *path, struct inode *inode,
bool rcu)
bool atime_needs_update(const struct path *path, struct inode *inode)
{
struct vfsmount *mnt = path->mnt;
struct timespec64 now;
@ -1736,7 +1702,7 @@ bool __atime_needs_update(const struct path *path, struct inode *inode,
now = current_time(inode);
if (!relatime_need_update(path, inode, timespec64_to_timespec(now), rcu))
if (!relatime_need_update(mnt, inode, timespec64_to_timespec(now)))
return false;
if (timespec64_equal(&inode->i_atime, &now))
@ -1751,7 +1717,7 @@ void touch_atime(const struct path *path)
struct inode *inode = d_inode(path->dentry);
struct timespec64 now;
if (!__atime_needs_update(path, inode, false))
if (!atime_needs_update(path, inode))
return;
if (!sb_start_write_trylock(inode->i_sb))

11
fs/internal.h
View File

@ -82,10 +82,8 @@ extern void __init mnt_init(void);
extern int __mnt_want_write(struct vfsmount *);
extern int __mnt_want_write_file(struct file *);
extern int mnt_want_write_file_path(struct file *);
extern void __mnt_drop_write(struct vfsmount *);
extern void __mnt_drop_write_file(struct file *);
extern void mnt_drop_write_file_path(struct file *);
/*
* fs_struct.c
@ -96,6 +94,7 @@ extern void chroot_fs_refs(const struct path *, const struct path *);
* file_table.c
*/
extern struct file *alloc_empty_file(int, const struct cred *);
extern struct file *alloc_empty_file_noaccount(int, const struct cred *);
/*
* super.c
@ -136,13 +135,6 @@ extern long prune_icache_sb(struct super_block *sb, struct shrink_control *sc);
extern void inode_add_lru(struct inode *inode);
extern int dentry_needs_remove_privs(struct dentry *dentry);
extern bool __atime_needs_update(const struct path *, struct inode *, bool);
static inline bool atime_needs_update_rcu(const struct path *path,
struct inode *inode)
{
return __atime_needs_update(path, inode, true);
}
/*
* fs-writeback.c
*/
@ -185,7 +177,6 @@ extern const struct dentry_operations ns_dentry_operations;
*/
extern int do_vfs_ioctl(struct file *file, unsigned int fd, unsigned int cmd,
unsigned long arg);
extern long vfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
/*
* iomap support:

1
fs/ioctl.c
View File

@ -49,6 +49,7 @@ long vfs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
out:
return error;
}
EXPORT_SYMBOL(vfs_ioctl);
static int ioctl_fibmap(struct file *filp, int __user *p)
{

20
fs/locks.c
View File

@ -139,11 +139,6 @@
#define IS_OFDLCK(fl) (fl->fl_flags & FL_OFDLCK)
#define IS_REMOTELCK(fl) (fl->fl_pid <= 0)
static inline bool is_remote_lock(struct file *filp)
{
return likely(!(filp->f_path.dentry->d_sb->s_flags & SB_NOREMOTELOCK));
}
static bool lease_breaking(struct file_lock *fl)
{
return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
@ -1651,8 +1646,7 @@ check_conflicting_open(const struct dentry *dentry, const long arg, int flags)
if (flags & FL_LAYOUT)
return 0;
if ((arg == F_RDLCK) &&
(atomic_read(&d_real_inode(dentry)->i_writecount) > 0))
if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
return -EAGAIN;
if ((arg == F_WRLCK) && ((d_count(dentry) > 1) ||
@ -1873,7 +1867,7 @@ EXPORT_SYMBOL(generic_setlease);
int
vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv)
{
if (filp->f_op->setlease && is_remote_lock(filp))
if (filp->f_op->setlease)
return filp->f_op->setlease(filp, arg, lease, priv);
else
return generic_setlease(filp, arg, lease, priv);
@ -2020,7 +2014,7 @@ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
if (error)
goto out_free;
if (f.file->f_op->flock && is_remote_lock(f.file))
if (f.file->f_op->flock)
error = f.file->f_op->flock(f.file,
(can_sleep) ? F_SETLKW : F_SETLK,
lock);
@ -2046,7 +2040,7 @@ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
*/
int vfs_test_lock(struct file *filp, struct file_lock *fl)
{
if (filp->f_op->lock && is_remote_lock(filp))
if (filp->f_op->lock)
return filp->f_op->lock(filp, F_GETLK, fl);
posix_test_lock(filp, fl);
return 0;
@ -2196,7 +2190,7 @@ out:
*/
int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
{
if (filp->f_op->lock && is_remote_lock(filp))
if (filp->f_op->lock)
return filp->f_op->lock(filp, cmd, fl);
else
return posix_lock_file(filp, fl, conf);
@ -2518,7 +2512,7 @@ locks_remove_flock(struct file *filp, struct file_lock_context *flctx)
if (list_empty(&flctx->flc_flock))
return;
if (filp->f_op->flock && is_remote_lock(filp))
if (filp->f_op->flock)
filp->f_op->flock(filp, F_SETLKW, &fl);
else
flock_lock_inode(inode, &fl);
@ -2605,7 +2599,7 @@ EXPORT_SYMBOL(posix_unblock_lock);
*/
int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
{
if (filp->f_op->lock && is_remote_lock(filp))
if (filp->f_op->lock)
return filp->f_op->lock(filp, F_CANCELLK, fl);
return 0;
}

2
fs/namei.c
View File

@ -1015,7 +1015,7 @@ const char *get_link(struct nameidata *nd)
if (!(nd->flags & LOOKUP_RCU)) {
touch_atime(&last->link);
cond_resched();
} else if (atime_needs_update_rcu(&last->link, inode)) {
} else if (atime_needs_update(&last->link, inode)) {
if (unlikely(unlazy_walk(nd)))
return ERR_PTR(-ECHILD);
touch_atime(&last->link);

69
fs/namespace.c
View File

@ -430,75 +430,21 @@ int __mnt_want_write_file(struct file *file)
return mnt_clone_write(file->f_path.mnt);
}
/**
* mnt_want_write_file_path - get write access to a file's mount
* @file: the file who's mount on which to take a write
*
* This is like mnt_want_write, but it takes a file and can
* do some optimisations if the file is open for write already
*
* Called by the vfs for cases when we have an open file at hand, but will do an
* inode operation on it (important distinction for files opened on overlayfs,
* since the file operations will come from the real underlying file, while
* inode operations come from the overlay).
*/
int mnt_want_write_file_path(struct file *file)
{
int ret;
sb_start_write(file->f_path.mnt->mnt_sb);
ret = __mnt_want_write_file(file);
if (ret)
sb_end_write(file->f_path.mnt->mnt_sb);
return ret;
}
static inline int may_write_real(struct file *file)
{
struct dentry *dentry = file->f_path.dentry;
struct dentry *upperdentry;
/* Writable file? */
if (file->f_mode & FMODE_WRITER)
return 0;
/* Not overlayfs? */
if (likely(!(dentry->d_flags & DCACHE_OP_REAL)))
return 0;
/* File refers to upper, writable layer? */
upperdentry = d_real(dentry, NULL, 0, D_REAL_UPPER);
if (upperdentry &&
(file_inode(file) == d_inode(upperdentry) ||
file_inode(file) == d_inode(dentry)))
return 0;
/* Lower layer: can't write to real file, sorry... */
return -EPERM;
}
/**
* mnt_want_write_file - get write access to a file's mount
* @file: the file who's mount on which to take a write
*
* This is like mnt_want_write, but it takes a file and can
* do some optimisations if the file is open for write already
*
* Mostly called by filesystems from their ioctl operation before performing
* modification. On overlayfs this needs to check if the file is on a read-only
* lower layer and deny access in that case.
*/
int mnt_want_write_file(struct file *file)
{
int ret;
ret = may_write_real(file);
if (!ret) {
sb_start_write(file_inode(file)->i_sb);
ret = __mnt_want_write_file(file);
if (ret)
sb_end_write(file_inode(file)->i_sb);
}
sb_start_write(file_inode(file)->i_sb);
ret = __mnt_want_write_file(file);
if (ret)
sb_end_write(file_inode(file)->i_sb);
return ret;
}
EXPORT_SYMBOL_GPL(mnt_want_write_file);
@ -538,14 +484,9 @@ void __mnt_drop_write_file(struct file *file)
__mnt_drop_write(file->f_path.mnt);
}
void mnt_drop_write_file_path(struct file *file)
{
mnt_drop_write(file->f_path.mnt);
}
void mnt_drop_write_file(struct file *file)
{
__mnt_drop_write(file->f_path.mnt);
__mnt_drop_write_file(file);
sb_end_write(file_inode(file)->i_sb);
}
EXPORT_SYMBOL(mnt_drop_write_file);

17
fs/ocfs2/file.c
View File

@ -2537,19 +2537,14 @@ static int ocfs2_file_clone_range(struct file *file_in,
len, false);
}
static ssize_t ocfs2_file_dedupe_range(struct file *src_file,
u64 loff,
u64 len,
struct file *dst_file,
u64 dst_loff)
static int ocfs2_file_dedupe_range(struct file *file_in,
loff_t pos_in,
struct file *file_out,
loff_t pos_out,
u64 len)
{
int error;
error = ocfs2_reflink_remap_range(src_file, loff, dst_file, dst_loff,
return ocfs2_reflink_remap_range(file_in, pos_in, file_out, pos_out,
len, true);
if (error)
return error;
return len;
}
const struct inode_operations ocfs2_file_iops = {

44
fs/open.c
View File

@ -68,7 +68,6 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
long vfs_truncate(const struct path *path, loff_t length)
{
struct inode *inode;
struct dentry *upperdentry;
long error;
inode = path->dentry->d_inode;
@ -91,17 +90,7 @@ long vfs_truncate(const struct path *path, loff_t length)
if (IS_APPEND(inode))
goto mnt_drop_write_and_out;
/*
* If this is an overlayfs then do as if opening the file so we get
* write access on the upper inode, not on the overlay inode. For
* non-overlay filesystems d_real() is an identity function.
*/
upperdentry = d_real(path->dentry, NULL, O_WRONLY, 0);
error = PTR_ERR(upperdentry);
if (IS_ERR(upperdentry))
goto mnt_drop_write_and_out;
error = get_write_access(upperdentry->d_inode);
error = get_write_access(inode);
if (error)
goto mnt_drop_write_and_out;
@ -120,7 +109,7 @@ long vfs_truncate(const struct path *path, loff_t length)
error = do_truncate(path->dentry, length, 0, NULL);
put_write_and_out:
put_write_access(upperdentry->d_inode);
put_write_access(inode);
mnt_drop_write_and_out:
mnt_drop_write(path->mnt);
out:
@ -707,12 +696,12 @@ int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
if (!f.file)
goto out;
error = mnt_want_write_file_path(f.file);
error = mnt_want_write_file(f.file);
if (error)
goto out_fput;
audit_file(f.file);
error = chown_common(&f.file->f_path, user, group);
mnt_drop_write_file_path(f.file);
mnt_drop_write_file(f.file);
out_fput:
fdput(f);
out:
@ -887,13 +876,8 @@ EXPORT_SYMBOL(file_path);
*/
int vfs_open(const struct path *path, struct file *file)
{
struct dentry *dentry = d_real(path->dentry, NULL, file->f_flags, 0);
if (IS_ERR(dentry))
return PTR_ERR(dentry);
file->f_path = *path;
return do_dentry_open(file, d_backing_inode(dentry), NULL);
return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
}
struct file *dentry_open(const struct path *path, int flags,
@ -919,6 +903,24 @@ struct file *dentry_open(const struct path *path, int flags,
}
EXPORT_SYMBOL(dentry_open);
struct file *open_with_fake_path(const struct path *path, int flags,
struct inode *inode, const struct cred *cred)
{
struct file *f = alloc_empty_file_noaccount(flags, cred);
if (!IS_ERR(f)) {
int error;
f->f_path = *path;
error = do_dentry_open(f, inode, NULL);
if (error) {
fput(f);
f = ERR_PTR(error);
}
}
return f;
}
EXPORT_SYMBOL(open_with_fake_path);
static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
{
int lookup_flags = 0;

19
fs/overlayfs/Kconfig
View File

@ -64,6 +64,7 @@ config OVERLAY_FS_NFS_EXPORT
bool "Overlayfs: turn on NFS export feature by default"
depends on OVERLAY_FS
depends on OVERLAY_FS_INDEX
depends on !OVERLAY_FS_METACOPY
help
If this config option is enabled then overlay filesystems will use
the index directory to decode overlay NFS file handles by default.
@ -103,3 +104,21 @@ config OVERLAY_FS_XINO_AUTO
For more information, see Documentation/filesystems/overlayfs.txt
If unsure, say N.
config OVERLAY_FS_METACOPY
bool "Overlayfs: turn on metadata only copy up feature by default"
depends on OVERLAY_FS
select OVERLAY_FS_REDIRECT_DIR
help
If this config option is enabled then overlay filesystems will
copy up only metadata where appropriate and data copy up will
happen when a file is opened for WRITE operation. It is still
possible to turn off this feature globally with the "metacopy=off"
module option or on a filesystem instance basis with the
"metacopy=off" mount option.
Note, that this feature is not backward compatible. That is,
mounting an overlay which has metacopy only inodes on a kernel
that doesn't support this feature will have unexpected results.
If unsure, say N.

4
fs/overlayfs/Makefile
View File

@ -4,5 +4,5 @@
obj-$(CONFIG_OVERLAY_FS) += overlay.o
overlay-objs := super.o namei.o util.o inode.o dir.o readdir.o copy_up.o \
export.o
overlay-objs := super.o namei.o util.o inode.o file.o dir.o readdir.o \
copy_up.o export.o

190
fs/overlayfs/copy_up.c
View File

@ -25,35 +25,20 @@
#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
static bool __read_mostly ovl_check_copy_up;
module_param_named(check_copy_up, ovl_check_copy_up, bool,
S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(ovl_check_copy_up,
"Warn on copy-up when causing process also has a R/O fd open");
static int ovl_check_fd(const void *data, struct file *f, unsigned int fd)
static int ovl_ccup_set(const char *buf, const struct kernel_param *param)
{
const struct dentry *dentry = data;
if (file_inode(f) == d_inode(dentry))
pr_warn_ratelimited("overlayfs: Warning: Copying up %pD, but open R/O on fd %u which will cease to be coherent [pid=%d %s]\n",
f, fd, current->pid, current->comm);
pr_warn("overlayfs: \"check_copy_up\" module option is obsolete\n");
return 0;
}
/*
* Check the fds open by this process and warn if something like the following
* scenario is about to occur:
*
* fd1 = open("foo", O_RDONLY);
* fd2 = open("foo", O_RDWR);
*/
static void ovl_do_check_copy_up(struct dentry *dentry)
static int ovl_ccup_get(char *buf, const struct kernel_param *param)
{
if (ovl_check_copy_up)
iterate_fd(current->files, 0, ovl_check_fd, dentry);
return sprintf(buf, "N\n");
}
module_param_call(check_copy_up, ovl_ccup_set, ovl_ccup_get, NULL, 0644);
MODULE_PARM_DESC(ovl_check_copy_up, "Obsolete; does nothing");
int ovl_copy_xattr(struct dentry *old, struct dentry *new)
{
ssize_t list_size, size, value_size = 0;
@ -195,6 +180,16 @@ out_fput:
return error;
}
static int ovl_set_size(struct dentry *upperdentry, struct kstat *stat)
{
struct iattr attr = {
.ia_valid = ATTR_SIZE,
.ia_size = stat->size,
};
return notify_change(upperdentry, &attr, NULL);
}
static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
{
struct iattr attr = {
@ -403,6 +398,7 @@ struct ovl_copy_up_ctx {
bool tmpfile;
bool origin;
bool indexed;
bool metacopy;
};
static int ovl_link_up(struct ovl_copy_up_ctx *c)
@ -505,28 +501,10 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
{
int err;
if (S_ISREG(c->stat.mode)) {
struct path upperpath;
ovl_path_upper(c->dentry, &upperpath);
BUG_ON(upperpath.dentry != NULL);
upperpath.dentry = temp;
err = ovl_copy_up_data(&c->lowerpath, &upperpath, c->stat.size);
if (err)
return err;
}
err = ovl_copy_xattr(c->lowerpath.dentry, temp);
if (err)
return err;
inode_lock(temp->d_inode);
err = ovl_set_attr(temp, &c->stat);
inode_unlock(temp->d_inode);
if (err)
return err;
/*
* Store identifier of lower inode in upper inode xattr to
* allow lookup of the copy up origin inode.
@ -540,7 +518,34 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
return err;
}
return 0;
if (S_ISREG(c->stat.mode) && !c->metacopy) {
struct path upperpath, datapath;
ovl_path_upper(c->dentry, &upperpath);
BUG_ON(upperpath.dentry != NULL);
upperpath.dentry = temp;
ovl_path_lowerdata(c->dentry, &datapath);
err = ovl_copy_up_data(&datapath, &upperpath, c->stat.size);
if (err)
return err;
}
if (c->metacopy) {
err = ovl_check_setxattr(c->dentry, temp, OVL_XATTR_METACOPY,
NULL, 0, -EOPNOTSUPP);
if (err)
return err;
}
inode_lock(temp->d_inode);
if (c->metacopy)
err = ovl_set_size(temp, &c->stat);
if (!err)
err = ovl_set_attr(temp, &c->stat);
inode_unlock(temp->d_inode);
return err;
}
static int ovl_copy_up_locked(struct ovl_copy_up_ctx *c)
@ -575,6 +580,8 @@ static int ovl_copy_up_locked(struct ovl_copy_up_ctx *c)
if (err)
goto out;
if (!c->metacopy)
ovl_set_upperdata(d_inode(c->dentry));
inode = d_inode(c->dentry);
ovl_inode_update(inode, newdentry);
if (S_ISDIR(inode->i_mode))
@ -677,6 +684,49 @@ out:
return err;
}
static bool ovl_need_meta_copy_up(struct dentry *dentry, umode_t mode,
int flags)
{
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
if (!ofs->config.metacopy)
return false;
if (!S_ISREG(mode))
return false;
if (flags && ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC)))
return false;
return true;
}
/* Copy up data of an inode which was copied up metadata only in the past. */
static int ovl_copy_up_meta_inode_data(struct ovl_copy_up_ctx *c)
{
struct path upperpath, datapath;
int err;
ovl_path_upper(c->dentry, &upperpath);
if (WARN_ON(upperpath.dentry == NULL))
return -EIO;
ovl_path_lowerdata(c->dentry, &datapath);
if (WARN_ON(datapath.dentry == NULL))
return -EIO;
err = ovl_copy_up_data(&datapath, &upperpath, c->stat.size);
if (err)
return err;
err = vfs_removexattr(upperpath.dentry, OVL_XATTR_METACOPY);
if (err)
return err;
ovl_set_upperdata(d_inode(c->dentry));
return err;
}
static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
int flags)
{
@ -698,6 +748,8 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
if (err)
return err;
ctx.metacopy = ovl_need_meta_copy_up(dentry, ctx.stat.mode, flags);
if (parent) {
ovl_path_upper(parent, &parentpath);
ctx.destdir = parentpath.dentry;
@ -719,9 +771,8 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
if (IS_ERR(ctx.link))
return PTR_ERR(ctx.link);
}
ovl_do_check_copy_up(ctx.lowerpath.dentry);
err = ovl_copy_up_start(dentry);
err = ovl_copy_up_start(dentry, flags);
/* err < 0: interrupted, err > 0: raced with another copy-up */
if (unlikely(err)) {
if (err > 0)
@ -731,6 +782,8 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
err = ovl_do_copy_up(&ctx);
if (!err && parent && !ovl_dentry_has_upper_alias(dentry))
err = ovl_link_up(&ctx);
if (!err && ovl_dentry_needs_data_copy_up_locked(dentry, flags))
err = ovl_copy_up_meta_inode_data(&ctx);
ovl_copy_up_end(dentry);
}
do_delayed_call(&done);
@ -756,21 +809,7 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags)
struct dentry *next;
struct dentry *parent = NULL;
/*
* Check if copy-up has happened as well as for upper alias (in
* case of hard links) is there.
*
* Both checks are lockless:
* - false negatives: will recheck under oi->lock
* - false positives:
* + ovl_dentry_upper() uses memory barriers to ensure the
* upper dentry is up-to-date
* + ovl_dentry_has_upper_alias() relies on locking of
* upper parent i_rwsem to prevent reordering copy-up
* with rename.
*/
if (ovl_dentry_upper(dentry) &&
(ovl_dentry_has_upper_alias(dentry) || disconnected))
if (ovl_already_copied_up(dentry, flags))
break;
next = dget(dentry);
@ -795,6 +834,41 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags)
return err;
}
static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)
{
/* Copy up of disconnected dentry does not set upper alias */
if (ovl_already_copied_up(dentry, flags))
return false;
if (special_file(d_inode(dentry)->i_mode))
return false;
if (!ovl_open_flags_need_copy_up(flags))
return false;
return true;
}
int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags)
{
int err = 0;
if (ovl_open_need_copy_up(dentry, file_flags)) {
err = ovl_want_write(dentry);
if (!err) {
err = ovl_copy_up_flags(dentry, file_flags);
ovl_drop_write(dentry);
}
}
return err;
}
int ovl_copy_up_with_data(struct dentry *dentry)
{
return ovl_copy_up_flags(dentry, O_WRONLY);
}
int ovl_copy_up(struct dentry *dentry)
{
return ovl_copy_up_flags(dentry, 0);

105
fs/overlayfs/dir.c
View File

@ -24,6 +24,8 @@ module_param_named(redirect_max, ovl_redirect_max, ushort, 0644);
MODULE_PARM_DESC(ovl_redirect_max,
"Maximum length of absolute redirect xattr value");
static int ovl_set_redirect(struct dentry *dentry, bool samedir);
int ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
{
int err;
@ -242,7 +244,7 @@ static int ovl_instantiate(struct dentry *dentry, struct inode *inode,
.newinode = inode,
};
ovl_dentry_version_inc(dentry->d_parent, false);
ovl_dir_modified(dentry->d_parent, false);
ovl_dentry_set_upper_alias(dentry);
if (!hardlink) {
/*
@ -657,6 +659,12 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
if (err)
goto out_drop_write;
if (ovl_is_metacopy_dentry(old)) {
err = ovl_set_redirect(old, false);
if (err)
goto out_drop_write;
}
err = ovl_nlink_start(old, &locked);
if (err)
goto out_drop_write;
@ -722,7 +730,7 @@ static int ovl_remove_and_whiteout(struct dentry *dentry,
if (err)
goto out_d_drop;
ovl_dentry_version_inc(dentry->d_parent, true);
ovl_dir_modified(dentry->d_parent, true);
out_d_drop:
d_drop(dentry);
out_dput_upper:
@ -767,7 +775,7 @@ static int ovl_remove_upper(struct dentry *dentry, bool is_dir,
err = vfs_rmdir(dir, upper);
else
err = vfs_unlink(dir, upper, NULL);
ovl_dentry_version_inc(dentry->d_parent, ovl_type_origin(dentry));
ovl_dir_modified(dentry->d_parent, ovl_type_origin(dentry));
/*
* Keeping this dentry hashed would mean having to release
@ -797,6 +805,7 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
int err;
bool locked = false;
const struct cred *old_cred;
struct dentry *upperdentry;
bool lower_positive = ovl_lower_positive(dentry);
LIST_HEAD(list);
@ -832,6 +841,17 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
drop_nlink(dentry->d_inode);
}
ovl_nlink_end(dentry, locked);
/*
* Copy ctime
*
* Note: we fail to update ctime if there was no copy-up, only a
* whiteout
*/
upperdentry = ovl_dentry_upper(dentry);
if (upperdentry)
ovl_copyattr(d_inode(upperdentry), d_inode(dentry));
out_drop_write:
ovl_drop_write(dentry);
out:
@ -862,13 +882,13 @@ static bool ovl_can_move(struct dentry *dentry)
!d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry);
}
static char *ovl_get_redirect(struct dentry *dentry, bool samedir)
static char *ovl_get_redirect(struct dentry *dentry, bool abs_redirect)
{
char *buf, *ret;
struct dentry *d, *tmp;
int buflen = ovl_redirect_max + 1;
if (samedir) {
if (!abs_redirect) {
ret = kstrndup(dentry->d_name.name, dentry->d_name.len,
GFP_KERNEL);
goto out;
@ -922,15 +942,43 @@ out:
return ret ? ret : ERR_PTR(-ENOMEM);
}
static bool ovl_need_absolute_redirect(struct dentry *dentry, bool samedir)
{
struct dentry *lowerdentry;
if (!samedir)
return true;
if (d_is_dir(dentry))
return false;
/*
* For non-dir hardlinked files, we need absolute redirects
* in general as two upper hardlinks could be in different
* dirs. We could put a relative redirect now and convert
* it to absolute redirect later. But when nlink > 1 and
* indexing is on, that means relative redirect needs to be
* converted to absolute during copy up of another lower
* hardllink as well.
*
* So without optimizing too much, just check if lower is
* a hard link or not. If lower is hard link, put absolute
* redirect.
*/
lowerdentry = ovl_dentry_lower(dentry);
return (d_inode(lowerdentry)->i_nlink > 1);
}
static int ovl_set_redirect(struct dentry *dentry, bool samedir)
{
int err;
const char *redirect = ovl_dentry_get_redirect(dentry);
bool absolute_redirect = ovl_need_absolute_redirect(dentry, samedir);
if (redirect && (samedir || redirect[0] == '/'))
if (redirect && (!absolute_redirect || redirect[0] == '/'))
return 0;
redirect = ovl_get_redirect(dentry, samedir);
redirect = ovl_get_redirect(dentry, absolute_redirect);
if (IS_ERR(redirect))
return PTR_ERR(redirect);
@ -1106,22 +1154,20 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
goto out_dput;
err = 0;
if (is_dir) {
if (ovl_type_merge_or_lower(old))
err = ovl_set_redirect(old, samedir);
else if (!old_opaque && ovl_type_merge(new->d_parent))
err = ovl_set_opaque_xerr(old, olddentry, -EXDEV);
if (err)
goto out_dput;
}
if (!overwrite && new_is_dir) {
if (ovl_type_merge_or_lower(new))
err = ovl_set_redirect(new, samedir);
else if (!new_opaque && ovl_type_merge(old->d_parent))
err = ovl_set_opaque_xerr(new, newdentry, -EXDEV);
if (err)
goto out_dput;
}
if (ovl_type_merge_or_lower(old))
err = ovl_set_redirect(old, samedir);
else if (is_dir && !old_opaque && ovl_type_merge(new->d_parent))
err = ovl_set_opaque_xerr(old, olddentry, -EXDEV);
if (err)
goto out_dput;
if (!overwrite && ovl_type_merge_or_lower(new))
err = ovl_set_redirect(new, samedir);
else if (!overwrite && new_is_dir && !new_opaque &&
ovl_type_merge(old->d_parent))
err = ovl_set_opaque_xerr(new, newdentry, -EXDEV);
if (err)
goto out_dput;
err = ovl_do_rename(old_upperdir->d_inode, olddentry,
new_upperdir->d_inode, newdentry, flags);
@ -1138,10 +1184,15 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
drop_nlink(d_inode(new));
}
ovl_dentry_version_inc(old->d_parent, ovl_type_origin(old) ||
(!overwrite && ovl_type_origin(new)));
ovl_dentry_version_inc(new->d_parent, ovl_type_origin(old) ||
(d_inode(new) && ovl_type_origin(new)));
ovl_dir_modified(old->d_parent, ovl_type_origin(old) ||
(!overwrite && ovl_type_origin(new)));
ovl_dir_modified(new->d_parent, ovl_type_origin(old) ||
(d_inode(new) && ovl_type_origin(new)));
/* copy ctime: */
ovl_copyattr(d_inode(olddentry), d_inode(old));
if (d_inode(new) && ovl_dentry_upper(new))
ovl_copyattr(d_inode(newdentry), d_inode(new));
out_dput:
dput(newdentry);

3
fs/overlayfs/export.c
View File

@ -317,6 +317,9 @@ static struct dentry *ovl_obtain_alias(struct super_block *sb,
return ERR_CAST(inode);
}
if (upper)
ovl_set_flag(OVL_UPPERDATA, inode);
dentry = d_find_any_alias(inode);
if (!dentry) {
dentry = d_alloc_anon(inode->i_sb);

511
fs/overlayfs/file.c Normal file
View File

@ -0,0 +1,511 @@
/*
* Copyright (C) 2017 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/cred.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/xattr.h>
#include <linux/uio.h>
#include "overlayfs.h"
static char ovl_whatisit(struct inode *inode, struct inode *realinode)
{
if (realinode != ovl_inode_upper(inode))
return 'l';
if (ovl_has_upperdata(inode))
return 'u';
else
return 'm';
}
static struct file *ovl_open_realfile(const struct file *file,
struct inode *realinode)
{
struct inode *inode = file_inode(file);
struct file *realfile;
const struct cred *old_cred;
old_cred = ovl_override_creds(inode->i_sb);
realfile = open_with_fake_path(&file->f_path, file->f_flags | O_NOATIME,
realinode, current_cred());
revert_creds(old_cred);
pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
file, file, ovl_whatisit(inode, realinode), file->f_flags,
realfile, IS_ERR(realfile) ? 0 : realfile->f_flags);
return realfile;
}
#define OVL_SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT)
static int ovl_change_flags(struct file *file, unsigned int flags)
{
struct inode *inode = file_inode(file);
int err;
/* No atime modificaton on underlying */
flags |= O_NOATIME;
/* If some flag changed that cannot be changed then something's amiss */
if (WARN_ON((file->f_flags ^ flags) & ~OVL_SETFL_MASK))
return -EIO;
flags &= OVL_SETFL_MASK;
if (((flags ^ file->f_flags) & O_APPEND) && IS_APPEND(inode))
return -EPERM;
if (flags & O_DIRECT) {
if (!file->f_mapping->a_ops ||
!file->f_mapping->a_ops->direct_IO)
return -EINVAL;
}
if (file->f_op->check_flags) {
err = file->f_op->check_flags(flags);
if (err)
return err;
}
spin_lock(&file->f_lock);
file->f_flags = (file->f_flags & ~OVL_SETFL_MASK) | flags;
spin_unlock(&file->f_lock);
return 0;
}
static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
bool allow_meta)
{
struct inode *inode = file_inode(file);
struct inode *realinode;
real->flags = 0;
real->file = file->private_data;
if (allow_meta)
realinode = ovl_inode_real(inode);
else
realinode = ovl_inode_realdata(inode);
/* Has it been copied up since we'd opened it? */
if (unlikely(file_inode(real->file) != realinode)) {
real->flags = FDPUT_FPUT;
real->file = ovl_open_realfile(file, realinode);
return PTR_ERR_OR_ZERO(real->file);
}
/* Did the flags change since open? */
if (unlikely((file->f_flags ^ real->file->f_flags) & ~O_NOATIME))
return ovl_change_flags(real->file, file->f_flags);
return 0;
}
static int ovl_real_fdget(const struct file *file, struct fd *real)
{
return ovl_real_fdget_meta(file, real, false);
}
static int ovl_open(struct inode *inode, struct file *file)
{
struct dentry *dentry = file_dentry(file);
struct file *realfile;
int err;
err = ovl_open_maybe_copy_up(dentry, file->f_flags);
if (err)
return err;
/* No longer need these flags, so don't pass them on to underlying fs */
file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
realfile = ovl_open_realfile(file, ovl_inode_realdata(inode));
if (IS_ERR(realfile))
return PTR_ERR(realfile);
/* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */
file->f_mapping = realfile->f_mapping;
file->private_data = realfile;
return 0;
}
static int ovl_release(struct inode *inode, struct file *file)
{
fput(file->private_data);
return 0;
}
static loff_t ovl_llseek(struct file *file, loff_t offset, int whence)
{
struct inode *realinode = ovl_inode_real(file_inode(file));
return generic_file_llseek_size(file, offset, whence,
realinode->i_sb->s_maxbytes,
i_size_read(realinode));
}
static void ovl_file_accessed(struct file *file)
{
struct inode *inode, *upperinode;
if (file->f_flags & O_NOATIME)
return;
inode = file_inode(file);
upperinode = ovl_inode_upper(inode);
if (!upperinode)
return;
if ((!timespec64_equal(&inode->i_mtime, &upperinode->i_mtime) ||
!timespec64_equal(&inode->i_ctime, &upperinode->i_ctime))) {
inode->i_mtime = upperinode->i_mtime;
inode->i_ctime = upperinode->i_ctime;
}
touch_atime(&file->f_path);
}
static rwf_t ovl_iocb_to_rwf(struct kiocb *iocb)
{
int ifl = iocb->ki_flags;
rwf_t flags = 0;
if (ifl & IOCB_NOWAIT)
flags |= RWF_NOWAIT;
if (ifl & IOCB_HIPRI)
flags |= RWF_HIPRI;
if (ifl & IOCB_DSYNC)
flags |= RWF_DSYNC;
if (ifl & IOCB_SYNC)
flags |= RWF_SYNC;
return flags;
}
static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{
struct file *file = iocb->ki_filp;
struct fd real;
const struct cred *old_cred;
ssize_t ret;
if (!iov_iter_count(iter))
return 0;
ret = ovl_real_fdget(file, &real);
if (ret)
return ret;
old_cred = ovl_override_creds(file_inode(file)->i_sb);
ret = vfs_iter_read(real.file, iter, &iocb->ki_pos,
ovl_iocb_to_rwf(iocb));
revert_creds(old_cred);
ovl_file_accessed(file);
fdput(real);
return ret;
}
static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
{
struct file *file = iocb->ki_filp;
struct inode *inode = file_inode(file);
struct fd real;
const struct cred *old_cred;
ssize_t ret;
if (!iov_iter_count(iter))
return 0;
inode_lock(inode);
/* Update mode */
ovl_copyattr(ovl_inode_real(inode), inode);
ret = file_remove_privs(file);
if (ret)
goto out_unlock;
ret = ovl_real_fdget(file, &real);
if (ret)
goto out_unlock;
old_cred = ovl_override_creds(file_inode(file)->i_sb);
ret = vfs_iter_write(real.file, iter, &iocb->ki_pos,
ovl_iocb_to_rwf(iocb));
revert_creds(old_cred);
/* Update size */
ovl_copyattr(ovl_inode_real(inode), inode);
fdput(real);
out_unlock:
inode_unlock(inode);
return ret;
}
static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
struct fd real;
const struct cred *old_cred;
int ret;
ret = ovl_real_fdget_meta(file, &real, !datasync);
if (ret)
return ret;
/* Don't sync lower file for fear of receiving EROFS error */
if (file_inode(real.file) == ovl_inode_upper(file_inode(file))) {
old_cred = ovl_override_creds(file_inode(file)->i_sb);
ret = vfs_fsync_range(real.file, start, end, datasync);
revert_creds(old_cred);
}
fdput(real);
return ret;
}
static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
{
struct file *realfile = file->private_data;
const struct cred *old_cred;
int ret;
if (!realfile->f_op->mmap)
return -ENODEV;
if (WARN_ON(file != vma->vm_file))
return -EIO;
vma->vm_file = get_file(realfile);
old_cred = ovl_override_creds(file_inode(file)->i_sb);
ret = call_mmap(vma->vm_file, vma);
revert_creds(old_cred);
if (ret) {
/* Drop reference count from new vm_file value */
fput(realfile);
} else {
/* Drop reference count from previous vm_file value */
fput(file);
}
ovl_file_accessed(file);
return ret;
}
static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
{
struct inode *inode = file_inode(file);
struct fd real;
const struct cred *old_cred;
int ret;
ret = ovl_real_fdget(file, &real);
if (ret)
return ret;
old_cred = ovl_override_creds(file_inode(file)->i_sb);
ret = vfs_fallocate(real.file, mode, offset, len);
revert_creds(old_cred);
/* Update size */
ovl_copyattr(ovl_inode_real(inode), inode);
fdput(real);
return ret;
}
static long ovl_real_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct fd real;
const struct cred *old_cred;
long ret;
ret = ovl_real_fdget(file, &real);
if (ret)
return ret;
old_cred = ovl_override_creds(file_inode(file)->i_sb);
ret = vfs_ioctl(real.file, cmd, arg);
revert_creds(old_cred);
fdput(real);
return ret;
}
static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
long ret;
struct inode *inode = file_inode(file);
switch (cmd) {
case FS_IOC_GETFLAGS:
ret = ovl_real_ioctl(file, cmd, arg);
break;
case FS_IOC_SETFLAGS:
if (!inode_owner_or_capable(inode))
return -EACCES;
ret = mnt_want_write_file(file);
if (ret)
return ret;
ret = ovl_copy_up_with_data(file_dentry(file));
if (!ret) {
ret = ovl_real_ioctl(file, cmd, arg);
inode_lock(inode);
ovl_copyflags(ovl_inode_real(inode), inode);
inode_unlock(inode);
}
mnt_drop_write_file(file);
break;
default:
ret = -ENOTTY;
}
return ret;
}
static long ovl_compat_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
switch (cmd) {
case FS_IOC32_GETFLAGS:
cmd = FS_IOC_GETFLAGS;
break;
case FS_IOC32_SETFLAGS:
cmd = FS_IOC_SETFLAGS;
break;
default:
return -ENOIOCTLCMD;
}
return ovl_ioctl(file, cmd, arg);
}
enum ovl_copyop {
OVL_COPY,
OVL_CLONE,
OVL_DEDUPE,
};
static ssize_t ovl_copyfile(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
u64 len, unsigned int flags, enum ovl_copyop op)
{
struct inode *inode_out = file_inode(file_out);
struct fd real_in, real_out;
const struct cred *old_cred;
ssize_t ret;
ret = ovl_real_fdget(file_out, &real_out);
if (ret)
return ret;
ret = ovl_real_fdget(file_in, &real_in);
if (ret) {
fdput(real_out);
return ret;
}
old_cred = ovl_override_creds(file_inode(file_out)->i_sb);
switch (op) {
case OVL_COPY:
ret = vfs_copy_file_range(real_in.file, pos_in,
real_out.file, pos_out, len, flags);
break;
case OVL_CLONE:
ret = vfs_clone_file_range(real_in.file, pos_in,
real_out.file, pos_out, len);
break;
case OVL_DEDUPE:
ret = vfs_dedupe_file_range_one(real_in.file, pos_in,
real_out.file, pos_out, len);
break;
}
revert_creds(old_cred);
/* Update size */
ovl_copyattr(ovl_inode_real(inode_out), inode_out);
fdput(real_in);
fdput(real_out);
return ret;
}
static ssize_t ovl_copy_file_range(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
size_t len, unsigned int flags)
{
return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, flags,
OVL_COPY);
}
static int ovl_clone_file_range(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out, u64 len)
{
return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, 0,
OVL_CLONE);
}
static int ovl_dedupe_file_range(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out, u64 len)
{
/*
* Don't copy up because of a dedupe request, this wouldn't make sense
* most of the time (data would be duplicated instead of deduplicated).
*/
if (!ovl_inode_upper(file_inode(file_in)) ||
!ovl_inode_upper(file_inode(file_out)))
return -EPERM;
return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, 0,
OVL_DEDUPE);
}
const struct file_operations ovl_file_operations = {
.open = ovl_open,
.release = ovl_release,
.llseek = ovl_llseek,
.read_iter = ovl_read_iter,
.write_iter = ovl_write_iter,
.fsync = ovl_fsync,
.mmap = ovl_mmap,
.fallocate = ovl_fallocate,
.unlocked_ioctl = ovl_ioctl,
.compat_ioctl = ovl_compat_ioctl,
.copy_file_range = ovl_copy_file_range,
.clone_file_range = ovl_clone_file_range,
.dedupe_file_range = ovl_dedupe_file_range,
};

175
fs/overlayfs/inode.c
View File

@ -19,18 +19,10 @@
int ovl_setattr(struct dentry *dentry, struct iattr *attr)
{
int err;
bool full_copy_up = false;
struct dentry *upperdentry;
const struct cred *old_cred;
/*
* Check for permissions before trying to copy-up. This is redundant
* since it will be rechecked later by ->setattr() on upper dentry. But
* without this, copy-up can be triggered by just about anybody.
*
* We don't initialize inode->size, which just means that
* inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not
* check for a swapfile (which this won't be anyway).
*/
err = setattr_prepare(dentry, attr);
if (err)
return err;
@ -39,10 +31,33 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
if (err)
goto out;
err = ovl_copy_up(dentry);
if (attr->ia_valid & ATTR_SIZE) {
struct inode *realinode = d_inode(ovl_dentry_real(dentry));
err = -ETXTBSY;
if (atomic_read(&realinode->i_writecount) < 0)
goto out_drop_write;
/* Truncate should trigger data copy up as well */
full_copy_up = true;
}
if (!full_copy_up)
err = ovl_copy_up(dentry);
else
err = ovl_copy_up_with_data(dentry);
if (!err) {
struct inode *winode = NULL;
upperdentry = ovl_dentry_upper(dentry);
if (attr->ia_valid & ATTR_SIZE) {
winode = d_inode(upperdentry);
err = get_write_access(winode);
if (err)
goto out_drop_write;
}
if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
attr->ia_valid &= ~ATTR_MODE;
@ -53,7 +68,11 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
if (!err)
ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
inode_unlock(upperdentry->d_inode);
if (winode)
put_write_access(winode);
}
out_drop_write:
ovl_drop_write(dentry);
out:
return err;
@ -133,6 +152,9 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
bool samefs = ovl_same_sb(dentry->d_sb);
struct ovl_layer *lower_layer = NULL;
int err;
bool metacopy_blocks = false;
metacopy_blocks = ovl_is_metacopy_dentry(dentry);
type = ovl_path_real(dentry, &realpath);
old_cred = ovl_override_creds(dentry->d_sb);
@ -154,7 +176,8 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
lower_layer = ovl_layer_lower(dentry);
} else if (OVL_TYPE_ORIGIN(type)) {
struct kstat lowerstat;
u32 lowermask = STATX_INO | (!is_dir ? STATX_NLINK : 0);
u32 lowermask = STATX_INO | STATX_BLOCKS |
(!is_dir ? STATX_NLINK : 0);
ovl_path_lower(dentry, &realpath);
err = vfs_getattr(&realpath, &lowerstat,
@ -183,6 +206,35 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
stat->ino = lowerstat.ino;
lower_layer = ovl_layer_lower(dentry);
}
/*
* If we are querying a metacopy dentry and lower
* dentry is data dentry, then use the blocks we
* queried just now. We don't have to do additional
* vfs_getattr(). If lower itself is metacopy, then
* additional vfs_getattr() is unavoidable.
*/
if (metacopy_blocks &&
realpath.dentry == ovl_dentry_lowerdata(dentry)) {
stat->blocks = lowerstat.blocks;
metacopy_blocks = false;
}
}
if (metacopy_blocks) {
/*
* If lower is not same as lowerdata or if there was
* no origin on upper, we can end up here.
*/
struct kstat lowerdatastat;
u32 lowermask = STATX_BLOCKS;
ovl_path_lowerdata(dentry, &realpath);
err = vfs_getattr(&realpath, &lowerdatastat,
lowermask, flags);
if (err)
goto out;
stat->blocks = lowerdatastat.blocks;
}
}
@ -304,6 +356,9 @@ int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
}
revert_creds(old_cred);
/* copy c/mtime */
ovl_copyattr(d_inode(realdentry), inode);
out_drop_write:
ovl_drop_write(dentry);
out:
@ -384,38 +439,6 @@ struct posix_acl *ovl_get_acl(struct inode *inode, int type)
return acl;
}
static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)
{
/* Copy up of disconnected dentry does not set upper alias */
if (ovl_dentry_upper(dentry) &&
(ovl_dentry_has_upper_alias(dentry) ||
(dentry->d_flags & DCACHE_DISCONNECTED)))
return false;
if (special_file(d_inode(dentry)->i_mode))
return false;
if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC))
return false;
return true;
}
int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags)
{
int err = 0;
if (ovl_open_need_copy_up(dentry, file_flags)) {
err = ovl_want_write(dentry);
if (!err) {
err = ovl_copy_up_flags(dentry, file_flags);
ovl_drop_write(dentry);
}
}
return err;
}
int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags)
{
if (flags & S_ATIME) {
@ -433,6 +456,23 @@ int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags)
return 0;
}
static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
u64 start, u64 len)
{
int err;
struct inode *realinode = ovl_inode_real(inode);
const struct cred *old_cred;
if (!realinode->i_op->fiemap)
return -EOPNOTSUPP;
old_cred = ovl_override_creds(inode->i_sb);
err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
revert_creds(old_cred);
return err;
}
static const struct inode_operations ovl_file_inode_operations = {
.setattr = ovl_setattr,
.permission = ovl_permission,
@ -440,6 +480,7 @@ static const struct inode_operations ovl_file_inode_operations = {
.listxattr = ovl_listxattr,
.get_acl = ovl_get_acl,
.update_time = ovl_update_time,
.fiemap = ovl_fiemap,
};
static const struct inode_operations ovl_symlink_inode_operations = {
@ -450,6 +491,15 @@ static const struct inode_operations ovl_symlink_inode_operations = {
.update_time = ovl_update_time,
};
static const struct inode_operations ovl_special_inode_operations = {
.setattr = ovl_setattr,
.permission = ovl_permission,
.getattr = ovl_getattr,
.listxattr = ovl_listxattr,
.get_acl = ovl_get_acl,
.update_time = ovl_update_time,
};
/*
* It is possible to stack overlayfs instance on top of another
* overlayfs instance as lower layer. We need to annonate the
@ -520,6 +570,7 @@ static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev,
switch (mode & S_IFMT) {
case S_IFREG:
inode->i_op = &ovl_file_inode_operations;
inode->i_fop = &ovl_file_operations;
break;
case S_IFDIR:
@ -532,7 +583,7 @@ static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev,
break;
default:
inode->i_op = &ovl_file_inode_operations;
inode->i_op = &ovl_special_inode_operations;
init_special_inode(inode, mode, rdev);
break;
}
@ -769,8 +820,9 @@ struct inode *ovl_get_inode(struct super_block *sb,
bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry,
oip->index);
int fsid = bylower ? oip->lowerpath->layer->fsid : 0;
bool is_dir;
bool is_dir, metacopy = false;
unsigned long ino = 0;
int err = -ENOMEM;
if (!realinode)
realinode = d_inode(lowerdentry);
@ -787,7 +839,7 @@ struct inode *ovl_get_inode(struct super_block *sb,
inode = ovl_iget5(sb, oip->newinode, key);
if (!inode)
goto out_nomem;
goto out_err;
if (!(inode->i_state & I_NEW)) {
/*
* Verify that the underlying files stored in the inode
@ -796,11 +848,12 @@ struct inode *ovl_get_inode(struct super_block *sb,
if (!ovl_verify_inode(inode, lowerdentry, upperdentry,
true)) {
iput(inode);
inode = ERR_PTR(-ESTALE);
goto out;
err = -ESTALE;
goto out_err;
}
dput(upperdentry);
kfree(oip->redirect);
goto out;
}
@ -812,11 +865,13 @@ struct inode *ovl_get_inode(struct super_block *sb,
} else {
/* Lower hardlink that will be broken on copy up */
inode = new_inode(sb);
if (!inode)
goto out_nomem;
if (!inode) {
err = -ENOMEM;
goto out_err;
}
}
ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev, ino, fsid);
ovl_inode_init(inode, upperdentry, lowerdentry);
ovl_inode_init(inode, upperdentry, lowerdentry, oip->lowerdata);
if (upperdentry && ovl_is_impuredir(upperdentry))
ovl_set_flag(OVL_IMPURE, inode);
@ -824,6 +879,20 @@ struct inode *ovl_get_inode(struct super_block *sb,
if (oip->index)
ovl_set_flag(OVL_INDEX, inode);
if (upperdentry) {
err = ovl_check_metacopy_xattr(upperdentry);
if (err < 0)
goto out_err;
metacopy = err;
if (!metacopy)
ovl_set_flag(OVL_UPPERDATA, inode);
}
OVL_I(inode)->redirect = oip->redirect;
if (bylower)
ovl_set_flag(OVL_CONST_INO, inode);
/* Check for non-merge dir that may have whiteouts */
if (is_dir) {
if (((upperdentry && lowerdentry) || oip->numlower > 1) ||
@ -837,7 +906,7 @@ struct inode *ovl_get_inode(struct super_block *sb,
out:
return inode;
out_nomem:
inode = ERR_PTR(-ENOMEM);
out_err:
inode = ERR_PTR(err);
goto out;
}

195
fs/overlayfs/namei.c
View File

@ -24,38 +24,20 @@ struct ovl_lookup_data {
bool stop;
bool last;
char *redirect;
bool metacopy;
};
static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
size_t prelen, const char *post)
{
int res;
char *s, *next, *buf = NULL;
char *buf;
res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, NULL, 0);
if (res < 0) {
if (res == -ENODATA || res == -EOPNOTSUPP)
return 0;
goto fail;
}
buf = kzalloc(prelen + res + strlen(post) + 1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
buf = ovl_get_redirect_xattr(dentry, prelen + strlen(post));
if (IS_ERR_OR_NULL(buf))
return PTR_ERR(buf);
if (res == 0)
goto invalid;
res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, buf, res);
if (res < 0)
goto fail;
if (res == 0)
goto invalid;
if (buf[0] == '/') {
for (s = buf; *s++ == '/'; s = next) {
next = strchrnul(s, '/');
if (s == next)
goto invalid;
}
/*
* One of the ancestor path elements in an absolute path
* lookup in ovl_lookup_layer() could have been opaque and
@ -66,9 +48,7 @@ static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
*/
d->stop = false;
} else {
if (strchr(buf, '/') != NULL)
goto invalid;
res = strlen(buf) + 1;
memmove(buf + prelen, buf, res);
memcpy(buf, d->name.name, prelen);
}
@ -80,16 +60,6 @@ static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
d->name.len = strlen(d->redirect);
return 0;
err_free:
kfree(buf);
return 0;
fail:
pr_warn_ratelimited("overlayfs: failed to get redirect (%i)\n", res);
goto err_free;
invalid:
pr_warn_ratelimited("overlayfs: invalid redirect (%s)\n", buf);
goto err_free;
}
static int ovl_acceptable(void *ctx, struct dentry *dentry)
@ -252,28 +222,39 @@ static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
d->stop = d->opaque = true;
goto put_and_out;
}
if (!d_can_lookup(this)) {
/*
* This dentry should be a regular file if previous layer lookup
* found a metacopy dentry.
*/
if (last_element && d->metacopy && !d_is_reg(this)) {
d->stop = true;
if (d->is_dir)
goto put_and_out;
/*
* NB: handle failure to lookup non-last element when non-dir
* redirects become possible
*/
WARN_ON(!last_element);
goto out;
goto put_and_out;
}
if (last_element)
d->is_dir = true;
if (d->last)
goto out;
if (!d_can_lookup(this)) {
if (d->is_dir || !last_element) {
d->stop = true;
goto put_and_out;
}
err = ovl_check_metacopy_xattr(this);
if (err < 0)
goto out_err;
if (ovl_is_opaquedir(this)) {
d->stop = true;
d->metacopy = err;
d->stop = !d->metacopy;
if (!d->metacopy || d->last)
goto out;
} else {
if (last_element)
d->opaque = true;
goto out;
d->is_dir = true;
if (d->last)
goto out;
if (ovl_is_opaquedir(this)) {
d->stop = true;
if (last_element)
d->opaque = true;
goto out;
}
}
err = ovl_check_redirect(this, d, prelen, post);
if (err)
@ -823,7 +804,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
struct ovl_entry *poe = dentry->d_parent->d_fsdata;
struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata;
struct ovl_path *stack = NULL;
struct ovl_path *stack = NULL, *origin_path = NULL;
struct dentry *upperdir, *upperdentry = NULL;
struct dentry *origin = NULL;
struct dentry *index = NULL;
@ -834,6 +815,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
struct dentry *this;
unsigned int i;
int err;
bool metacopy = false;
struct ovl_lookup_data d = {
.name = dentry->d_name,
.is_dir = false,
@ -841,6 +823,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
.stop = false,
.last = ofs->config.redirect_follow ? false : !poe->numlower,
.redirect = NULL,
.metacopy = false,
};
if (dentry->d_name.len > ofs->namelen)
@ -859,7 +842,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
goto out;
}
if (upperdentry && !d.is_dir) {
BUG_ON(!d.stop || d.redirect);
unsigned int origin_ctr = 0;
/*
* Lookup copy up origin by decoding origin file handle.
* We may get a disconnected dentry, which is fine,
@ -870,9 +854,13 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
* number - it's the same as if we held a reference
* to a dentry in lower layer that was moved under us.
*/
err = ovl_check_origin(ofs, upperdentry, &stack, &ctr);
err = ovl_check_origin(ofs, upperdentry, &origin_path,
&origin_ctr);
if (err)
goto out_put_upper;
if (d.metacopy)
metacopy = true;
}
if (d.redirect) {
@ -913,7 +901,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
* If no origin fh is stored in upper of a merge dir, store fh
* of lower dir and set upper parent "impure".
*/
if (upperdentry && !ctr && !ofs->noxattr) {
if (upperdentry && !ctr && !ofs->noxattr && d.is_dir) {
err = ovl_fix_origin(dentry, this, upperdentry);
if (err) {
dput(this);
@ -925,18 +913,35 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
* When "verify_lower" feature is enabled, do not merge with a
* lower dir that does not match a stored origin xattr. In any
* case, only verified origin is used for index lookup.
*
* For non-dir dentry, if index=on, then ensure origin
* matches the dentry found using path based lookup,
* otherwise error out.
*/
if (upperdentry && !ctr && ovl_verify_lower(dentry->d_sb)) {
if (upperdentry && !ctr &&
((d.is_dir && ovl_verify_lower(dentry->d_sb)) ||
(!d.is_dir && ofs->config.index && origin_path))) {
err = ovl_verify_origin(upperdentry, this, false);
if (err) {
dput(this);
break;
if (d.is_dir)
break;
goto out_put;
}
/* Bless lower dir as verified origin */
origin = this;
}
if (d.metacopy)
metacopy = true;
/*
* Do not store intermediate metacopy dentries in chain,
* except top most lower metacopy dentry
*/
if (d.metacopy && ctr) {
dput(this);
continue;
}
stack[ctr].dentry = this;
stack[ctr].layer = lower.layer;
ctr++;
@ -968,13 +973,48 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
}
}
if (metacopy) {
/*
* Found a metacopy dentry but did not find corresponding
* data dentry
*/
if (d.metacopy) {
err = -EIO;
goto out_put;
}
err = -EPERM;
if (!ofs->config.metacopy) {
pr_warn_ratelimited("overlay: refusing to follow metacopy origin for (%pd2)\n",
dentry);
goto out_put;
}
} else if (!d.is_dir && upperdentry && !ctr && origin_path) {
if (WARN_ON(stack != NULL)) {
err = -EIO;
goto out_put;
}
stack = origin_path;
ctr = 1;
origin_path = NULL;
}
/*
* Lookup index by lower inode and verify it matches upper inode.
* We only trust dir index if we verified that lower dir matches
* origin, otherwise dir index entries may be inconsistent and we
* ignore them. Always lookup index of non-dir and non-upper.
* ignore them.
*
* For non-dir upper metacopy dentry, we already set "origin" if we
* verified that lower matched upper origin. If upper origin was
* not present (because lower layer did not support fh encode/decode),
* or indexing is not enabled, do not set "origin" and skip looking up
* index. This case should be handled in same way as a non-dir upper
* without ORIGIN is handled.
*
* Always lookup index of non-dir non-metacopy and non-upper.
*/
if (ctr && (!upperdentry || !d.is_dir))
if (ctr && (!upperdentry || (!d.is_dir && !metacopy)))
origin = stack[0].dentry;
if (origin && ovl_indexdir(dentry->d_sb) &&
@ -1000,8 +1040,15 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
if (upperdentry)
ovl_dentry_set_upper_alias(dentry);
else if (index)
else if (index) {
upperdentry = dget(index);
upperredirect = ovl_get_redirect_xattr(upperdentry, 0);
if (IS_ERR(upperredirect)) {
err = PTR_ERR(upperredirect);
upperredirect = NULL;
goto out_free_oe;
}
}
if (upperdentry || ctr) {
struct ovl_inode_params oip = {
@ -1009,22 +1056,22 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
.lowerpath = stack,
.index = index,
.numlower = ctr,
.redirect = upperredirect,
.lowerdata = (ctr > 1 && !d.is_dir) ?
stack[ctr - 1].dentry : NULL,
};
inode = ovl_get_inode(dentry->d_sb, &oip);
err = PTR_ERR(inode);
if (IS_ERR(inode))
goto out_free_oe;
/*
* NB: handle redirected hard links when non-dir redirects
* become possible
*/
WARN_ON(OVL_I(inode)->redirect);
OVL_I(inode)->redirect = upperredirect;
}
revert_creds(old_cred);
if (origin_path) {
dput(origin_path->dentry);
kfree(origin_path);
}
dput(index);
kfree(stack);
kfree(d.redirect);
@ -1039,6 +1086,10 @@ out_put:
dput(stack[i].dentry);
kfree(stack);
out_put_upper:
if (origin_path) {
dput(origin_path->dentry);
kfree(origin_path);
}
dput(upperdentry);
kfree(upperredirect);
out:

47
fs/overlayfs/overlayfs.h
View File

@ -9,6 +9,7 @@
#include <linux/kernel.h>
#include <linux/uuid.h>
#include <linux/fs.h>
#include "ovl_entry.h"
enum ovl_path_type {
@ -28,6 +29,7 @@ enum ovl_path_type {
#define OVL_XATTR_IMPURE OVL_XATTR_PREFIX "impure"
#define OVL_XATTR_NLINK OVL_XATTR_PREFIX "nlink"
#define OVL_XATTR_UPPER OVL_XATTR_PREFIX "upper"
#define OVL_XATTR_METACOPY OVL_XATTR_PREFIX "metacopy"
enum ovl_inode_flag {
/* Pure upper dir that may contain non pure upper entries */
@ -35,6 +37,9 @@ enum ovl_inode_flag {
/* Non-merge dir that may contain whiteout entries */
OVL_WHITEOUTS,
OVL_INDEX,
OVL_UPPERDATA,
/* Inode number will remain constant over copy up. */
OVL_CONST_INO,
};
enum ovl_entry_flag {
@ -190,6 +195,14 @@ static inline struct dentry *ovl_do_tmpfile(struct dentry *dentry, umode_t mode)
return ret;
}
static inline bool ovl_open_flags_need_copy_up(int flags)
{
if (!flags)
return false;
return ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC));
}
/* util.c */
int ovl_want_write(struct dentry *dentry);
void ovl_drop_write(struct dentry *dentry);
@ -206,15 +219,19 @@ bool ovl_dentry_weird(struct dentry *dentry);
enum ovl_path_type ovl_path_type(struct dentry *dentry);
void ovl_path_upper(struct dentry *dentry, struct path *path);
void ovl_path_lower(struct dentry *dentry, struct path *path);
void ovl_path_lowerdata(struct dentry *dentry, struct path *path);
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
struct dentry *ovl_dentry_upper(struct dentry *dentry);
struct dentry *ovl_dentry_lower(struct dentry *dentry);
struct dentry *ovl_dentry_lowerdata(struct dentry *dentry);
struct ovl_layer *ovl_layer_lower(struct dentry *dentry);
struct dentry *ovl_dentry_real(struct dentry *dentry);
struct dentry *ovl_i_dentry_upper(struct inode *inode);
struct inode *ovl_inode_upper(struct inode *inode);
struct inode *ovl_inode_lower(struct inode *inode);
struct inode *ovl_inode_lowerdata(struct inode *inode);
struct inode *ovl_inode_real(struct inode *inode);
struct inode *ovl_inode_realdata(struct inode *inode);
struct ovl_dir_cache *ovl_dir_cache(struct inode *inode);
void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache);
void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry);
@ -225,18 +242,23 @@ bool ovl_dentry_is_whiteout(struct dentry *dentry);
void ovl_dentry_set_opaque(struct dentry *dentry);
bool ovl_dentry_has_upper_alias(struct dentry *dentry);
void ovl_dentry_set_upper_alias(struct dentry *dentry);
bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags);
bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags);
bool ovl_has_upperdata(struct inode *inode);
void ovl_set_upperdata(struct inode *inode);
bool ovl_redirect_dir(struct super_block *sb);
const char *ovl_dentry_get_redirect(struct dentry *dentry);
void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect);
void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
struct dentry *lowerdentry);
struct dentry *lowerdentry, struct dentry *lowerdata);
void ovl_inode_update(struct inode *inode, struct dentry *upperdentry);
void ovl_dentry_version_inc(struct dentry *dentry, bool impurity);
void ovl_dir_modified(struct dentry *dentry, bool impurity);
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);
int ovl_copy_up_start(struct dentry *dentry);
int ovl_copy_up_start(struct dentry *dentry, int flags);
void ovl_copy_up_end(struct dentry *dentry);
bool ovl_already_copied_up(struct dentry *dentry, int flags);
bool ovl_check_origin_xattr(struct dentry *dentry);
bool ovl_check_dir_xattr(struct dentry *dentry, const char *name);
int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
@ -252,6 +274,9 @@ bool ovl_need_index(struct dentry *dentry);
int ovl_nlink_start(struct dentry *dentry, bool *locked);
void ovl_nlink_end(struct dentry *dentry, bool locked);
int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir);
int ovl_check_metacopy_xattr(struct dentry *dentry);
bool ovl_is_metacopy_dentry(struct dentry *dentry);
char *ovl_get_redirect_xattr(struct dentry *dentry, int padding);
static inline bool ovl_is_impuredir(struct dentry *dentry)
{
@ -324,7 +349,6 @@ int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
void *value, size_t size);
ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
struct posix_acl *ovl_get_acl(struct inode *inode, int type);
int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags);
int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags);
bool ovl_is_private_xattr(const char *name);
@ -334,6 +358,8 @@ struct ovl_inode_params {
struct ovl_path *lowerpath;
struct dentry *index;
unsigned int numlower;
char *redirect;
struct dentry *lowerdata;
};
struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev);
struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
@ -348,6 +374,14 @@ static inline void ovl_copyattr(struct inode *from, struct inode *to)
to->i_atime = from->i_atime;
to->i_mtime = from->i_mtime;
to->i_ctime = from->i_ctime;
i_size_write(to, i_size_read(from));
}
static inline void ovl_copyflags(struct inode *from, struct inode *to)
{
unsigned int mask = S_SYNC | S_IMMUTABLE | S_APPEND | S_NOATIME;
inode_set_flags(to, from->i_flags & mask, mask);
}
/* dir.c */
@ -368,9 +402,14 @@ struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry,
int ovl_cleanup(struct inode *dir, struct dentry *dentry);
struct dentry *ovl_create_temp(struct dentry *workdir, struct ovl_cattr *attr);
/* file.c */
extern const struct file_operations ovl_file_operations;
/* copy_up.c */
int ovl_copy_up(struct dentry *dentry);
int ovl_copy_up_with_data(struct dentry *dentry);
int ovl_copy_up_flags(struct dentry *dentry, int flags);
int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags);
int ovl_copy_xattr(struct dentry *old, struct dentry *new);
int ovl_set_attr(struct dentry *upper, struct kstat *stat);
struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper);

6
fs/overlayfs/ovl_entry.h
View File

@ -19,6 +19,7 @@ struct ovl_config {
bool index;
bool nfs_export;
int xino;
bool metacopy;
};
struct ovl_sb {
@ -88,7 +89,10 @@ static inline struct ovl_entry *OVL_E(struct dentry *dentry)
}
struct ovl_inode {
struct ovl_dir_cache *cache;
union {
struct ovl_dir_cache *cache; /* directory */
struct inode *lowerdata; /* regular file */
};
const char *redirect;
u64 version;
unsigned long flags;

19
fs/overlayfs/readdir.c
View File

@ -668,6 +668,21 @@ static int ovl_fill_real(struct dir_context *ctx, const char *name,
return orig_ctx->actor(orig_ctx, name, namelen, offset, ino, d_type);
}
static bool ovl_is_impure_dir(struct file *file)
{
struct ovl_dir_file *od = file->private_data;
struct inode *dir = d_inode(file->f_path.dentry);
/*
* Only upper dir can be impure, but if we are in the middle of
* iterating a lower real dir, dir could be copied up and marked
* impure. We only want the impure cache if we started iterating
* a real upper dir to begin with.
*/
return od->is_upper && ovl_test_flag(OVL_IMPURE, dir);
}
static int ovl_iterate_real(struct file *file, struct dir_context *ctx)
{
int err;
@ -696,7 +711,7 @@ static int ovl_iterate_real(struct file *file, struct dir_context *ctx)
rdt.parent_ino = stat.ino;
}
if (ovl_test_flag(OVL_IMPURE, d_inode(dir))) {
if (ovl_is_impure_dir(file)) {
rdt.cache = ovl_cache_get_impure(&file->f_path);
if (IS_ERR(rdt.cache))
return PTR_ERR(rdt.cache);
@ -727,7 +742,7 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
*/
if (ovl_xino_bits(dentry->d_sb) ||
(ovl_same_sb(dentry->d_sb) &&
(ovl_test_flag(OVL_IMPURE, d_inode(dentry)) ||
(ovl_is_impure_dir(file) ||
OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {
return ovl_iterate_real(file, ctx);
}

103
fs/overlayfs/super.c
View File

@ -64,6 +64,11 @@ static void ovl_entry_stack_free(struct ovl_entry *oe)
dput(oe->lowerstack[i].dentry);
}
static bool ovl_metacopy_def = IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY);
module_param_named(metacopy, ovl_metacopy_def, bool, 0644);
MODULE_PARM_DESC(ovl_metacopy_def,
"Default to on or off for the metadata only copy up feature");
static void ovl_dentry_release(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
@ -74,31 +79,14 @@ static void ovl_dentry_release(struct dentry *dentry)
}
}
static int ovl_check_append_only(struct inode *inode, int flag)
{
/*
* This test was moot in vfs may_open() because overlay inode does
* not have the S_APPEND flag, so re-check on real upper inode
*/
if (IS_APPEND(inode)) {
if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
return -EPERM;
if (flag & O_TRUNC)
return -EPERM;
}
return 0;
}
static struct dentry *ovl_d_real(struct dentry *dentry,
const struct inode *inode,
unsigned int open_flags, unsigned int flags)
const struct inode *inode)
{
struct dentry *real;
int err;
if (flags & D_REAL_UPPER)
return ovl_dentry_upper(dentry);
/* It's an overlay file */
if (inode && d_inode(dentry) == inode)
return dentry;
if (!d_is_reg(dentry)) {
if (!inode || inode == d_inode(dentry))
@ -106,28 +94,19 @@ static struct dentry *ovl_d_real(struct dentry *dentry,
goto bug;
}
if (open_flags) {
err = ovl_open_maybe_copy_up(dentry, open_flags);
if (err)
return ERR_PTR(err);
}
real = ovl_dentry_upper(dentry);
if (real && (!inode || inode == d_inode(real))) {
if (!inode) {
err = ovl_check_append_only(d_inode(real), open_flags);
if (err)
return ERR_PTR(err);
}
if (real && (inode == d_inode(real)))
return real;
}
real = ovl_dentry_lower(dentry);
if (real && !inode && ovl_has_upperdata(d_inode(dentry)))
return real;
real = ovl_dentry_lowerdata(dentry);
if (!real)
goto bug;
/* Handle recursion */
real = d_real(real, inode, open_flags, 0);
real = d_real(real, inode);
if (!inode || inode == d_inode(real))
return real;
@ -205,6 +184,7 @@ static struct inode *ovl_alloc_inode(struct super_block *sb)
oi->flags = 0;
oi->__upperdentry = NULL;
oi->lower = NULL;
oi->lowerdata = NULL;
mutex_init(&oi->lock);
return &oi->vfs_inode;
@ -223,8 +203,11 @@ static void ovl_destroy_inode(struct inode *inode)
dput(oi->__upperdentry);
iput(oi->lower);
if (S_ISDIR(inode->i_mode))
ovl_dir_cache_free(inode);
else
iput(oi->lowerdata);
kfree(oi->redirect);
ovl_dir_cache_free(inode);
mutex_destroy(&oi->lock);
call_rcu(&inode->i_rcu, ovl_i_callback);
@ -376,6 +359,9 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
"on" : "off");
if (ofs->config.xino != ovl_xino_def())
seq_printf(m, ",xino=%s", ovl_xino_str[ofs->config.xino]);
if (ofs->config.metacopy != ovl_metacopy_def)
seq_printf(m, ",metacopy=%s",
ofs->config.metacopy ? "on" : "off");
return 0;
}
@ -413,6 +399,8 @@ enum {
OPT_XINO_ON,
OPT_XINO_OFF,
OPT_XINO_AUTO,
OPT_METACOPY_ON,
OPT_METACOPY_OFF,
OPT_ERR,
};
@ -429,6 +417,8 @@ static const match_table_t ovl_tokens = {
{OPT_XINO_ON, "xino=on"},
{OPT_XINO_OFF, "xino=off"},
{OPT_XINO_AUTO, "xino=auto"},
{OPT_METACOPY_ON, "metacopy=on"},
{OPT_METACOPY_OFF, "metacopy=off"},
{OPT_ERR, NULL}
};
@ -481,6 +471,7 @@ static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode)
static int ovl_parse_opt(char *opt, struct ovl_config *config)
{
char *p;
int err;
config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL);
if (!config->redirect_mode)
@ -555,6 +546,14 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
config->xino = OVL_XINO_AUTO;
break;
case OPT_METACOPY_ON:
config->metacopy = true;
break;
case OPT_METACOPY_OFF:
config->metacopy = false;
break;
default:
pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
return -EINVAL;
@ -569,7 +568,20 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
config->workdir = NULL;
}
return ovl_parse_redirect_mode(config, config->redirect_mode);
err = ovl_parse_redirect_mode(config, config->redirect_mode);
if (err)
return err;
/* metacopy feature with upper requires redirect_dir=on */
if (config->upperdir && config->metacopy && !config->redirect_dir) {
pr_warn("overlayfs: metadata only copy up requires \"redirect_dir=on\", falling back to metacopy=off.\n");
config->metacopy = false;
} else if (config->metacopy && !config->redirect_follow) {
pr_warn("overlayfs: metadata only copy up requires \"redirect_dir=follow\" on non-upper mount, falling back to metacopy=off.\n");
config->metacopy = false;
}
return 0;
}
#define OVL_WORKDIR_NAME "work"
@ -1042,7 +1054,8 @@ static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath)
if (err) {
ofs->noxattr = true;
ofs->config.index = false;
pr_warn("overlayfs: upper fs does not support xattr, falling back to index=off.\n");
ofs->config.metacopy = false;
pr_warn("overlayfs: upper fs does not support xattr, falling back to index=off and metacopy=off.\n");
err = 0;
} else {
vfs_removexattr(ofs->workdir, OVL_XATTR_OPAQUE);
@ -1064,7 +1077,6 @@ static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath)
pr_warn("overlayfs: NFS export requires \"index=on\", falling back to nfs_export=off.\n");
ofs->config.nfs_export = false;
}
out:
mnt_drop_write(mnt);
return err;
@ -1375,6 +1387,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
ofs->config.index = ovl_index_def;
ofs->config.nfs_export = ovl_nfs_export_def;
ofs->config.xino = ovl_xino_def();
ofs->config.metacopy = ovl_metacopy_def;
err = ovl_parse_opt((char *) data, &ofs->config);
if (err)
goto out_err;
@ -1445,6 +1458,11 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
}
}
if (ofs->config.metacopy && ofs->config.nfs_export) {
pr_warn("overlayfs: NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n");
ofs->config.nfs_export = false;
}
if (ofs->config.nfs_export)
sb->s_export_op = &ovl_export_operations;
@ -1455,7 +1473,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
sb->s_op = &ovl_super_operations;
sb->s_xattr = ovl_xattr_handlers;
sb->s_fs_info = ofs;
sb->s_flags |= SB_POSIXACL | SB_NOREMOTELOCK;
sb->s_flags |= SB_POSIXACL;
err = -ENOMEM;
root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0));
@ -1474,8 +1492,9 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
/* Root is always merge -> can have whiteouts */
ovl_set_flag(OVL_WHITEOUTS, d_inode(root_dentry));
ovl_dentry_set_flag(OVL_E_CONNECTED, root_dentry);
ovl_set_upperdata(d_inode(root_dentry));
ovl_inode_init(d_inode(root_dentry), upperpath.dentry,
ovl_dentry_lower(root_dentry));
ovl_dentry_lower(root_dentry), NULL);
sb->s_root = root_dentry;

252
fs/overlayfs/util.c
View File

@ -133,8 +133,10 @@ enum ovl_path_type ovl_path_type(struct dentry *dentry)
* Non-dir dentry can hold lower dentry of its copy up origin.
*/
if (oe->numlower) {
type |= __OVL_PATH_ORIGIN;
if (d_is_dir(dentry))
if (ovl_test_flag(OVL_CONST_INO, d_inode(dentry)))
type |= __OVL_PATH_ORIGIN;
if (d_is_dir(dentry) ||
!ovl_has_upperdata(d_inode(dentry)))
type |= __OVL_PATH_MERGE;
}
} else {
@ -164,6 +166,18 @@ void ovl_path_lower(struct dentry *dentry, struct path *path)
}
}
void ovl_path_lowerdata(struct dentry *dentry, struct path *path)
{
struct ovl_entry *oe = dentry->d_fsdata;
if (oe->numlower) {
path->mnt = oe->lowerstack[oe->numlower - 1].layer->mnt;
path->dentry = oe->lowerstack[oe->numlower - 1].dentry;
} else {
*path = (struct path) { };
}
}
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
{
enum ovl_path_type type = ovl_path_type(dentry);
@ -195,6 +209,19 @@ struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
return oe->numlower ? oe->lowerstack[0].layer : NULL;
}
/*
* ovl_dentry_lower() could return either a data dentry or metacopy dentry
* dependig on what is stored in lowerstack[0]. At times we need to find
* lower dentry which has data (and not metacopy dentry). This helper
* returns the lower data dentry.
*/
struct dentry *ovl_dentry_lowerdata(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
return oe->numlower ? oe->lowerstack[oe->numlower - 1].dentry : NULL;
}
struct dentry *ovl_dentry_real(struct dentry *dentry)
{
return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);
@ -222,6 +249,26 @@ struct inode *ovl_inode_real(struct inode *inode)
return ovl_inode_upper(inode) ?: ovl_inode_lower(inode);
}
/* Return inode which contains lower data. Do not return metacopy */
struct inode *ovl_inode_lowerdata(struct inode *inode)
{
if (WARN_ON(!S_ISREG(inode->i_mode)))
return NULL;
return OVL_I(inode)->lowerdata ?: ovl_inode_lower(inode);
}
/* Return real inode which contains data. Does not return metacopy inode */
struct inode *ovl_inode_realdata(struct inode *inode)
{
struct inode *upperinode;
upperinode = ovl_inode_upper(inode);
if (upperinode && ovl_has_upperdata(inode))
return upperinode;
return ovl_inode_lowerdata(inode);
}
struct ovl_dir_cache *ovl_dir_cache(struct inode *inode)
{
@ -279,6 +326,62 @@ void ovl_dentry_set_upper_alias(struct dentry *dentry)
ovl_dentry_set_flag(OVL_E_UPPER_ALIAS, dentry);
}
static bool ovl_should_check_upperdata(struct inode *inode)
{
if (!S_ISREG(inode->i_mode))
return false;
if (!ovl_inode_lower(inode))
return false;
return true;
}
bool ovl_has_upperdata(struct inode *inode)
{
if (!ovl_should_check_upperdata(inode))
return true;
if (!ovl_test_flag(OVL_UPPERDATA, inode))
return false;
/*
* Pairs with smp_wmb() in ovl_set_upperdata(). Main user of
* ovl_has_upperdata() is ovl_copy_up_meta_inode_data(). Make sure
* if setting of OVL_UPPERDATA is visible, then effects of writes
* before that are visible too.
*/
smp_rmb();
return true;
}
void ovl_set_upperdata(struct inode *inode)
{
/*
* Pairs with smp_rmb() in ovl_has_upperdata(). Make sure
* if OVL_UPPERDATA flag is visible, then effects of write operations
* before it are visible as well.
*/
smp_wmb();
ovl_set_flag(OVL_UPPERDATA, inode);
}
/* Caller should hold ovl_inode->lock */
bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags)
{
if (!ovl_open_flags_need_copy_up(flags))
return false;
return !ovl_test_flag(OVL_UPPERDATA, d_inode(dentry));
}
bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags)
{
if (!ovl_open_flags_need_copy_up(flags))
return false;
return !ovl_has_upperdata(d_inode(dentry));
}
bool ovl_redirect_dir(struct super_block *sb)
{
struct ovl_fs *ofs = sb->s_fs_info;
@ -300,7 +403,7 @@ void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect)
}
void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
struct dentry *lowerdentry)
struct dentry *lowerdentry, struct dentry *lowerdata)
{
struct inode *realinode = d_inode(upperdentry ?: lowerdentry);
@ -308,8 +411,11 @@ void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
OVL_I(inode)->__upperdentry = upperdentry;
if (lowerdentry)
OVL_I(inode)->lower = igrab(d_inode(lowerdentry));
if (lowerdata)
OVL_I(inode)->lowerdata = igrab(d_inode(lowerdata));
ovl_copyattr(realinode, inode);
ovl_copyflags(realinode, inode);
if (!inode->i_ino)
inode->i_ino = realinode->i_ino;
}
@ -333,7 +439,7 @@ void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
}
}
void ovl_dentry_version_inc(struct dentry *dentry, bool impurity)
static void ovl_dentry_version_inc(struct dentry *dentry, bool impurity)
{
struct inode *inode = d_inode(dentry);
@ -348,6 +454,14 @@ void ovl_dentry_version_inc(struct dentry *dentry, bool impurity)
OVL_I(inode)->version++;
}
void ovl_dir_modified(struct dentry *dentry, bool impurity)
{
/* Copy mtime/ctime */
ovl_copyattr(d_inode(ovl_dentry_upper(dentry)), d_inode(dentry));
ovl_dentry_version_inc(dentry, impurity);
}
u64 ovl_dentry_version_get(struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
@ -368,13 +482,51 @@ struct file *ovl_path_open(struct path *path, int flags)
return dentry_open(path, flags | O_NOATIME, current_cred());
}
int ovl_copy_up_start(struct dentry *dentry)
/* Caller should hold ovl_inode->lock */
static bool ovl_already_copied_up_locked(struct dentry *dentry, int flags)
{
bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
if (ovl_dentry_upper(dentry) &&
(ovl_dentry_has_upper_alias(dentry) || disconnected) &&
!ovl_dentry_needs_data_copy_up_locked(dentry, flags))
return true;
return false;
}
bool ovl_already_copied_up(struct dentry *dentry, int flags)
{
bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
/*
* Check if copy-up has happened as well as for upper alias (in
* case of hard links) is there.
*
* Both checks are lockless:
* - false negatives: will recheck under oi->lock
* - false positives:
* + ovl_dentry_upper() uses memory barriers to ensure the
* upper dentry is up-to-date
* + ovl_dentry_has_upper_alias() relies on locking of
* upper parent i_rwsem to prevent reordering copy-up
* with rename.
*/
if (ovl_dentry_upper(dentry) &&
(ovl_dentry_has_upper_alias(dentry) || disconnected) &&
!ovl_dentry_needs_data_copy_up(dentry, flags))
return true;
return false;
}
int ovl_copy_up_start(struct dentry *dentry, int flags)
{
struct ovl_inode *oi = OVL_I(d_inode(dentry));
int err;
err = mutex_lock_interruptible(&oi->lock);
if (!err && ovl_dentry_has_upper_alias(dentry)) {
if (!err && ovl_already_copied_up_locked(dentry, flags)) {
err = 1; /* Already copied up */
mutex_unlock(&oi->lock);
}
@ -675,3 +827,91 @@ err:
pr_err("overlayfs: failed to lock workdir+upperdir\n");
return -EIO;
}
/* err < 0, 0 if no metacopy xattr, 1 if metacopy xattr found */
int ovl_check_metacopy_xattr(struct dentry *dentry)
{
int res;
/* Only regular files can have metacopy xattr */
if (!S_ISREG(d_inode(dentry)->i_mode))
return 0;
res = vfs_getxattr(dentry, OVL_XATTR_METACOPY, NULL, 0);
if (res < 0) {
if (res == -ENODATA || res == -EOPNOTSUPP)
return 0;
goto out;
}
return 1;
out:
pr_warn_ratelimited("overlayfs: failed to get metacopy (%i)\n", res);
return res;
}
bool ovl_is_metacopy_dentry(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
if (!d_is_reg(dentry))
return false;
if (ovl_dentry_upper(dentry)) {
if (!ovl_has_upperdata(d_inode(dentry)))
return true;
return false;
}
return (oe->numlower > 1);
}
char *ovl_get_redirect_xattr(struct dentry *dentry, int padding)
{
int res;
char *s, *next, *buf = NULL;
res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, NULL, 0);
if (res < 0) {
if (res == -ENODATA || res == -EOPNOTSUPP)
return NULL;
goto fail;
}
buf = kzalloc(res + padding + 1, GFP_KERNEL);
if (!buf)
return ERR_PTR(-ENOMEM);
if (res == 0)
goto invalid;
res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, buf, res);
if (res < 0)
goto fail;
if (res == 0)
goto invalid;
if (buf[0] == '/') {
for (s = buf; *s++ == '/'; s = next) {
next = strchrnul(s, '/');
if (s == next)
goto invalid;
}
} else {
if (strchr(buf, '/') != NULL)
goto invalid;
}
return buf;
err_free:
kfree(buf);
return ERR_PTR(res);
fail:
pr_warn_ratelimited("overlayfs: failed to get redirect (%i)\n", res);
goto err_free;
invalid:
pr_warn_ratelimited("overlayfs: invalid redirect (%s)\n", buf);
res = -EINVAL;
goto err_free;
}

94
fs/read_write.c
View File

@ -1964,6 +1964,44 @@ out_error:
}
EXPORT_SYMBOL(vfs_dedupe_file_range_compare);
int vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
struct file *dst_file, loff_t dst_pos, u64 len)
{
s64 ret;
ret = mnt_want_write_file(dst_file);
if (ret)
return ret;
ret = clone_verify_area(dst_file, dst_pos, len, true);
if (ret < 0)
goto out_drop_write;
ret = -EINVAL;
if (!(capable(CAP_SYS_ADMIN) || (dst_file->f_mode & FMODE_WRITE)))
goto out_drop_write;
ret = -EXDEV;
if (src_file->f_path.mnt != dst_file->f_path.mnt)
goto out_drop_write;
ret = -EISDIR;
if (S_ISDIR(file_inode(dst_file)->i_mode))
goto out_drop_write;
ret = -EINVAL;
if (!dst_file->f_op->dedupe_file_range)
goto out_drop_write;
ret = dst_file->f_op->dedupe_file_range(src_file, src_pos,
dst_file, dst_pos, len);
out_drop_write:
mnt_drop_write_file(dst_file);
return ret;
}
EXPORT_SYMBOL(vfs_dedupe_file_range_one);
int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
{
struct file_dedupe_range_info *info;
@ -1972,11 +2010,8 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
u64 len;
int i;
int ret;
bool is_admin = capable(CAP_SYS_ADMIN);
u16 count = same->dest_count;
struct file *dst_file;
loff_t dst_off;
ssize_t deduped;
int deduped;
if (!(file->f_mode & FMODE_READ))
return -EINVAL;
@ -2003,6 +2038,9 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
if (off + len > i_size_read(src))
return -EINVAL;
/* Arbitrary 1G limit on a single dedupe request, can be raised. */
len = min_t(u64, len, 1 << 30);
/* pre-format output fields to sane values */
for (i = 0; i < count; i++) {
same->info[i].bytes_deduped = 0ULL;
@ -2010,54 +2048,28 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
}
for (i = 0, info = same->info; i < count; i++, info++) {
struct inode *dst;
struct fd dst_fd = fdget(info->dest_fd);
struct file *dst_file = dst_fd.file;
dst_file = dst_fd.file;
if (!dst_file) {
info->status = -EBADF;
goto next_loop;
}
dst = file_inode(dst_file);
ret = mnt_want_write_file(dst_file);
if (ret) {
info->status = ret;
goto next_fdput;
}
dst_off = info->dest_offset;
ret = clone_verify_area(dst_file, dst_off, len, true);
if (ret < 0) {
info->status = ret;
goto next_file;
}
ret = 0;
if (info->reserved) {
info->status = -EINVAL;
} else if (!(is_admin || (dst_file->f_mode & FMODE_WRITE))) {
info->status = -EINVAL;
} else if (file->f_path.mnt != dst_file->f_path.mnt) {
info->status = -EXDEV;
} else if (S_ISDIR(dst->i_mode)) {
info->status = -EISDIR;
} else if (dst_file->f_op->dedupe_file_range == NULL) {
info->status = -EINVAL;
} else {
deduped = dst_file->f_op->dedupe_file_range(file, off,
len, dst_file,
info->dest_offset);
if (deduped == -EBADE)
info->status = FILE_DEDUPE_RANGE_DIFFERS;
else if (deduped < 0)
info->status = deduped;
else
info->bytes_deduped += deduped;
goto next_fdput;
}
next_file:
mnt_drop_write_file(dst_file);
deduped = vfs_dedupe_file_range_one(file, off, dst_file,
info->dest_offset, len);
if (deduped == -EBADE)
info->status = FILE_DEDUPE_RANGE_DIFFERS;
else if (deduped < 0)
info->status = deduped;
else
info->bytes_deduped = len;
next_fdput:
fdput(dst_fd);
next_loop:

9
fs/xattr.c
View File

@ -23,7 +23,6 @@
#include <linux/posix_acl_xattr.h>
#include <linux/uaccess.h>
#include "internal.h"
static const char *
strcmp_prefix(const char *a, const char *a_prefix)
@ -501,10 +500,10 @@ SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
if (!f.file)
return error;
audit_file(f.file);
error = mnt_want_write_file_path(f.file);
error = mnt_want_write_file(f.file);
if (!error) {
error = setxattr(f.file->f_path.dentry, name, value, size, flags);
mnt_drop_write_file_path(f.file);
mnt_drop_write_file(f.file);
}
fdput(f);
return error;
@ -733,10 +732,10 @@ SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
if (!f.file)
return error;
audit_file(f.file);
error = mnt_want_write_file_path(f.file);
error = mnt_want_write_file(f.file);
if (!error) {
error = removexattr(f.file->f_path.dentry, name);
mnt_drop_write_file_path(f.file);
mnt_drop_write_file(f.file);
}
fdput(f);
return error;

29
fs/xfs/xfs_file.c
View File

@ -931,31 +931,16 @@ xfs_file_clone_range(
len, false);
}
STATIC ssize_t
STATIC int
xfs_file_dedupe_range(
struct file *src_file,
u64 loff,
u64 len,
struct file *dst_file,
u64 dst_loff)
struct file *file_in,
loff_t pos_in,
struct file *file_out,
loff_t pos_out,
u64 len)
{
struct inode *srci = file_inode(src_file);
u64 max_dedupe;
int error;
/*
* Since we have to read all these pages in to compare them, cut
* it off at MAX_RW_COUNT/2 rounded down to the nearest block.
* That means we won't do more than MAX_RW_COUNT IO per request.
*/
max_dedupe = (MAX_RW_COUNT >> 1) & ~(i_blocksize(srci) - 1);
if (len > max_dedupe)
len = max_dedupe;
error = xfs_reflink_remap_range(src_file, loff, dst_file, dst_loff,
return xfs_reflink_remap_range(file_in, pos_in, file_out, pos_out,
len, true);
if (error)
return error;
return len;
}
STATIC int

15
include/linux/dcache.h
View File

@ -145,8 +145,7 @@ struct dentry_operations {
char *(*d_dname)(struct dentry *, char *, int);
struct vfsmount *(*d_automount)(struct path *);
int (*d_manage)(const struct path *, bool);
struct dentry *(*d_real)(struct dentry *, const struct inode *,
unsigned int, unsigned int);
struct dentry *(*d_real)(struct dentry *, const struct inode *);
} ____cacheline_aligned;
/*
@ -561,15 +560,10 @@ static inline struct dentry *d_backing_dentry(struct dentry *upper)
return upper;
}
/* d_real() flags */
#define D_REAL_UPPER 0x2 /* return upper dentry or NULL if non-upper */
/**
* d_real - Return the real dentry
* @dentry: the dentry to query
* @inode: inode to select the dentry from multiple layers (can be NULL)
* @open_flags: open flags to control copy-up behavior
* @flags: flags to control what is returned by this function
*
* If dentry is on a union/overlay, then return the underlying, real dentry.
* Otherwise return the dentry itself.
@ -577,11 +571,10 @@ static inline struct dentry *d_backing_dentry(struct dentry *upper)
* See also: Documentation/filesystems/vfs.txt
*/
static inline struct dentry *d_real(struct dentry *dentry,
const struct inode *inode,
unsigned int open_flags, unsigned int flags)
const struct inode *inode)
{
if (unlikely(dentry->d_flags & DCACHE_OP_REAL))
return dentry->d_op->d_real(dentry, inode, open_flags, flags);
return dentry->d_op->d_real(dentry, inode);
else
return dentry;
}
@ -596,7 +589,7 @@ static inline struct dentry *d_real(struct dentry *dentry,
static inline struct inode *d_real_inode(const struct dentry *dentry)
{
/* This usage of d_real() results in const dentry */
return d_backing_inode(d_real((struct dentry *) dentry, NULL, 0, 0));
return d_backing_inode(d_real((struct dentry *) dentry, NULL));
}
struct name_snapshot {

29
include/linux/fs.h
View File

@ -157,6 +157,9 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
/* File is capable of returning -EAGAIN if I/O will block */
#define FMODE_NOWAIT ((__force fmode_t)0x8000000)
/* File does not contribute to nr_files count */
#define FMODE_NOACCOUNT ((__force fmode_t)0x20000000)
/*
* Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
* that indicates that they should check the contents of the iovec are
@ -1067,17 +1070,7 @@ struct file_lock_context {
extern void send_sigio(struct fown_struct *fown, int fd, int band);
/*
* Return the inode to use for locking
*
* For overlayfs this should be the overlay inode, not the real inode returned
* by file_inode(). For any other fs file_inode(filp) and locks_inode(filp) are
* equal.
*/
static inline struct inode *locks_inode(const struct file *f)
{
return f->f_path.dentry->d_inode;
}
#define locks_inode(f) file_inode(f)
#ifdef CONFIG_FILE_LOCKING
extern int fcntl_getlk(struct file *, unsigned int, struct flock *);
@ -1262,7 +1255,7 @@ static inline struct inode *file_inode(const struct file *f)
static inline struct dentry *file_dentry(const struct file *file)
{
return d_real(file->f_path.dentry, file_inode(file), 0, 0);
return d_real(file->f_path.dentry, file_inode(file));
}
static inline int locks_lock_file_wait(struct file *filp, struct file_lock *fl)
@ -1318,7 +1311,6 @@ extern int send_sigurg(struct fown_struct *fown);
/* These sb flags are internal to the kernel */
#define SB_SUBMOUNT (1<<26)
#define SB_NOREMOTELOCK (1<<27)
#define SB_NOSEC (1<<28)
#define SB_BORN (1<<29)
#define SB_ACTIVE (1<<30)
@ -1647,6 +1639,8 @@ int vfs_mkobj(struct dentry *, umode_t,
int (*f)(struct dentry *, umode_t, void *),
void *);
extern long vfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
/*
* VFS file helper functions.
*/
@ -1765,7 +1759,7 @@ struct file_operations {
loff_t, size_t, unsigned int);
int (*clone_file_range)(struct file *, loff_t, struct file *, loff_t,
u64);
ssize_t (*dedupe_file_range)(struct file *, u64, u64, struct file *,
int (*dedupe_file_range)(struct file *, loff_t, struct file *, loff_t,
u64);
} __randomize_layout;
@ -1838,6 +1832,10 @@ extern int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
loff_t len, bool *is_same);
extern int vfs_dedupe_file_range(struct file *file,
struct file_dedupe_range *same);
extern int vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
struct file *dst_file, loff_t dst_pos,
u64 len);
struct super_operations {
struct inode *(*alloc_inode)(struct super_block *sb);
@ -2096,6 +2094,7 @@ enum file_time_flags {
S_VERSION = 8,
};
extern bool atime_needs_update(const struct path *, struct inode *);
extern void touch_atime(const struct path *);
static inline void file_accessed(struct file *file)
{
@ -2441,6 +2440,8 @@ extern struct file *filp_open(const char *, int, umode_t);
extern struct file *file_open_root(struct dentry *, struct vfsmount *,
const char *, int, umode_t);
extern struct file * dentry_open(const struct path *, int, const struct cred *);
extern struct file * open_with_fake_path(const struct path *, int,
struct inode*, const struct cred *);
static inline struct file *file_clone_open(struct file *file)
{
return dentry_open(&file->f_path, file->f_flags, file->f_cred);

14
include/linux/fsnotify.h
View File

@ -30,11 +30,7 @@ static inline int fsnotify_parent(const struct path *path, struct dentry *dentry
static inline int fsnotify_perm(struct file *file, int mask)
{
const struct path *path = &file->f_path;
/*
* Do not use file_inode() here or anywhere in this file to get the
* inode. That would break *notity on overlayfs.
*/
struct inode *inode = path->dentry->d_inode;
struct inode *inode = file_inode(file);
__u32 fsnotify_mask = 0;
int ret;
@ -178,7 +174,7 @@ static inline void fsnotify_mkdir(struct inode *inode, struct dentry *dentry)
static inline void fsnotify_access(struct file *file)
{
const struct path *path = &file->f_path;
struct inode *inode = path->dentry->d_inode;
struct inode *inode = file_inode(file);
__u32 mask = FS_ACCESS;
if (S_ISDIR(inode->i_mode))
@ -196,7 +192,7 @@ static inline void fsnotify_access(struct file *file)
static inline void fsnotify_modify(struct file *file)
{
const struct path *path = &file->f_path;
struct inode *inode = path->dentry->d_inode;
struct inode *inode = file_inode(file);
__u32 mask = FS_MODIFY;
if (S_ISDIR(inode->i_mode))
@ -214,7 +210,7 @@ static inline void fsnotify_modify(struct file *file)
static inline void fsnotify_open(struct file *file)
{
const struct path *path = &file->f_path;
struct inode *inode = path->dentry->d_inode;
struct inode *inode = file_inode(file);
__u32 mask = FS_OPEN;
if (S_ISDIR(inode->i_mode))
@ -230,7 +226,7 @@ static inline void fsnotify_open(struct file *file)
static inline void fsnotify_close(struct file *file)
{
const struct path *path = &file->f_path;
struct inode *inode = path->dentry->d_inode;
struct inode *inode = file_inode(file);
fmode_t mode = file->f_mode;
__u32 mask = (mode & FMODE_WRITE) ? FS_CLOSE_WRITE : FS_CLOSE_NOWRITE;