2 * Copyright (C) 2011 Novell Inc.
3 * Copyright (C) 2016 Red Hat, Inc.
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 as published by
7 * the Free Software Foundation.
11 #include <linux/mount.h>
12 #include <linux/slab.h>
13 #include <linux/cred.h>
14 #include <linux/xattr.h>
15 #include <linux/exportfs.h>
16 #include <linux/uuid.h>
17 #include <linux/namei.h>
18 #include <linux/ratelimit.h>
19 #include "overlayfs.h"
20 #include "ovl_entry.h"
22 int ovl_want_write(struct dentry
*dentry
)
24 struct ovl_fs
*ofs
= dentry
->d_sb
->s_fs_info
;
25 return mnt_want_write(ofs
->upper_mnt
);
28 void ovl_drop_write(struct dentry
*dentry
)
30 struct ovl_fs
*ofs
= dentry
->d_sb
->s_fs_info
;
31 mnt_drop_write(ofs
->upper_mnt
);
34 struct dentry
*ovl_workdir(struct dentry
*dentry
)
36 struct ovl_fs
*ofs
= dentry
->d_sb
->s_fs_info
;
40 const struct cred
*ovl_override_creds(struct super_block
*sb
)
42 struct ovl_fs
*ofs
= sb
->s_fs_info
;
44 return override_creds(ofs
->creator_cred
);
47 struct super_block
*ovl_same_sb(struct super_block
*sb
)
49 struct ovl_fs
*ofs
= sb
->s_fs_info
;
54 bool ovl_can_decode_fh(struct super_block
*sb
)
56 return (sb
->s_export_op
&& sb
->s_export_op
->fh_to_dentry
&&
57 !uuid_is_null(&sb
->s_uuid
));
60 struct dentry
*ovl_indexdir(struct super_block
*sb
)
62 struct ovl_fs
*ofs
= sb
->s_fs_info
;
67 struct ovl_entry
*ovl_alloc_entry(unsigned int numlower
)
69 size_t size
= offsetof(struct ovl_entry
, lowerstack
[numlower
]);
70 struct ovl_entry
*oe
= kzalloc(size
, GFP_KERNEL
);
73 oe
->numlower
= numlower
;
78 bool ovl_dentry_remote(struct dentry
*dentry
)
80 return dentry
->d_flags
&
81 (DCACHE_OP_REVALIDATE
| DCACHE_OP_WEAK_REVALIDATE
|
85 bool ovl_dentry_weird(struct dentry
*dentry
)
87 return dentry
->d_flags
& (DCACHE_NEED_AUTOMOUNT
|
88 DCACHE_MANAGE_TRANSIT
|
93 enum ovl_path_type
ovl_path_type(struct dentry
*dentry
)
95 struct ovl_entry
*oe
= dentry
->d_fsdata
;
96 enum ovl_path_type type
= 0;
98 if (ovl_dentry_upper(dentry
)) {
99 type
= __OVL_PATH_UPPER
;
102 * Non-dir dentry can hold lower dentry of its copy up origin.
105 type
|= __OVL_PATH_ORIGIN
;
106 if (d_is_dir(dentry
))
107 type
|= __OVL_PATH_MERGE
;
110 if (oe
->numlower
> 1)
111 type
|= __OVL_PATH_MERGE
;
116 void ovl_path_upper(struct dentry
*dentry
, struct path
*path
)
118 struct ovl_fs
*ofs
= dentry
->d_sb
->s_fs_info
;
120 path
->mnt
= ofs
->upper_mnt
;
121 path
->dentry
= ovl_dentry_upper(dentry
);
124 void ovl_path_lower(struct dentry
*dentry
, struct path
*path
)
126 struct ovl_entry
*oe
= dentry
->d_fsdata
;
128 *path
= oe
->numlower
? oe
->lowerstack
[0] : (struct path
) { };
131 enum ovl_path_type
ovl_path_real(struct dentry
*dentry
, struct path
*path
)
133 enum ovl_path_type type
= ovl_path_type(dentry
);
135 if (!OVL_TYPE_UPPER(type
))
136 ovl_path_lower(dentry
, path
);
138 ovl_path_upper(dentry
, path
);
143 struct dentry
*ovl_dentry_upper(struct dentry
*dentry
)
145 return ovl_upperdentry_dereference(OVL_I(d_inode(dentry
)));
148 struct dentry
*ovl_dentry_lower(struct dentry
*dentry
)
150 struct ovl_entry
*oe
= dentry
->d_fsdata
;
152 return oe
->numlower
? oe
->lowerstack
[0].dentry
: NULL
;
155 struct dentry
*ovl_dentry_real(struct dentry
*dentry
)
157 return ovl_dentry_upper(dentry
) ?: ovl_dentry_lower(dentry
);
160 struct dentry
*ovl_i_dentry_upper(struct inode
*inode
)
162 return ovl_upperdentry_dereference(OVL_I(inode
));
165 struct inode
*ovl_inode_upper(struct inode
*inode
)
167 struct dentry
*upperdentry
= ovl_i_dentry_upper(inode
);
169 return upperdentry
? d_inode(upperdentry
) : NULL
;
172 struct inode
*ovl_inode_lower(struct inode
*inode
)
174 return OVL_I(inode
)->lower
;
177 struct inode
*ovl_inode_real(struct inode
*inode
)
179 return ovl_inode_upper(inode
) ?: ovl_inode_lower(inode
);
183 struct ovl_dir_cache
*ovl_dir_cache(struct inode
*inode
)
185 return OVL_I(inode
)->cache
;
188 void ovl_set_dir_cache(struct inode
*inode
, struct ovl_dir_cache
*cache
)
190 OVL_I(inode
)->cache
= cache
;
193 bool ovl_dentry_is_opaque(struct dentry
*dentry
)
195 struct ovl_entry
*oe
= dentry
->d_fsdata
;
199 bool ovl_dentry_is_whiteout(struct dentry
*dentry
)
201 return !dentry
->d_inode
&& ovl_dentry_is_opaque(dentry
);
204 void ovl_dentry_set_opaque(struct dentry
*dentry
)
206 struct ovl_entry
*oe
= dentry
->d_fsdata
;
212 * For hard links it's possible for ovl_dentry_upper() to return positive, while
213 * there's no actual upper alias for the inode. Copy up code needs to know
214 * about the existence of the upper alias, so it can't use ovl_dentry_upper().
216 bool ovl_dentry_has_upper_alias(struct dentry
*dentry
)
218 struct ovl_entry
*oe
= dentry
->d_fsdata
;
220 return oe
->has_upper
;
223 void ovl_dentry_set_upper_alias(struct dentry
*dentry
)
225 struct ovl_entry
*oe
= dentry
->d_fsdata
;
227 oe
->has_upper
= true;
230 bool ovl_redirect_dir(struct super_block
*sb
)
232 struct ovl_fs
*ofs
= sb
->s_fs_info
;
234 return ofs
->config
.redirect_dir
&& !ofs
->noxattr
;
237 const char *ovl_dentry_get_redirect(struct dentry
*dentry
)
239 return OVL_I(d_inode(dentry
))->redirect
;
242 void ovl_dentry_set_redirect(struct dentry
*dentry
, const char *redirect
)
244 struct ovl_inode
*oi
= OVL_I(d_inode(dentry
));
247 oi
->redirect
= redirect
;
250 void ovl_inode_init(struct inode
*inode
, struct dentry
*upperdentry
,
251 struct dentry
*lowerdentry
)
254 OVL_I(inode
)->__upperdentry
= upperdentry
;
256 OVL_I(inode
)->lower
= d_inode(lowerdentry
);
258 ovl_copyattr(d_inode(upperdentry
?: lowerdentry
), inode
);
261 void ovl_inode_update(struct inode
*inode
, struct dentry
*upperdentry
)
263 struct inode
*upperinode
= d_inode(upperdentry
);
265 WARN_ON(OVL_I(inode
)->__upperdentry
);
268 * Make sure upperdentry is consistent before making it visible
271 OVL_I(inode
)->__upperdentry
= upperdentry
;
272 if (!S_ISDIR(upperinode
->i_mode
) && inode_unhashed(inode
)) {
273 inode
->i_private
= upperinode
;
274 __insert_inode_hash(inode
, (unsigned long) upperinode
);
278 void ovl_dentry_version_inc(struct dentry
*dentry
, bool impurity
)
280 struct inode
*inode
= d_inode(dentry
);
282 WARN_ON(!inode_is_locked(inode
));
284 * Version is used by readdir code to keep cache consistent. For merge
285 * dirs all changes need to be noted. For non-merge dirs, cache only
286 * contains impure (ones which have been copied up and have origins)
287 * entries, so only need to note changes to impure entries.
289 if (OVL_TYPE_MERGE(ovl_path_type(dentry
)) || impurity
)
290 OVL_I(inode
)->version
++;
293 u64
ovl_dentry_version_get(struct dentry
*dentry
)
295 struct inode
*inode
= d_inode(dentry
);
297 WARN_ON(!inode_is_locked(inode
));
298 return OVL_I(inode
)->version
;
301 bool ovl_is_whiteout(struct dentry
*dentry
)
303 struct inode
*inode
= dentry
->d_inode
;
305 return inode
&& IS_WHITEOUT(inode
);
308 struct file
*ovl_path_open(struct path
*path
, int flags
)
310 return dentry_open(path
, flags
| O_NOATIME
, current_cred());
313 int ovl_copy_up_start(struct dentry
*dentry
)
315 struct ovl_inode
*oi
= OVL_I(d_inode(dentry
));
318 err
= mutex_lock_interruptible(&oi
->lock
);
319 if (!err
&& ovl_dentry_has_upper_alias(dentry
)) {
320 err
= 1; /* Already copied up */
321 mutex_unlock(&oi
->lock
);
327 void ovl_copy_up_end(struct dentry
*dentry
)
329 mutex_unlock(&OVL_I(d_inode(dentry
))->lock
);
332 bool ovl_check_dir_xattr(struct dentry
*dentry
, const char *name
)
337 if (!d_is_dir(dentry
))
340 res
= vfs_getxattr(dentry
, name
, &val
, 1);
341 if (res
== 1 && val
== 'y')
347 int ovl_check_setxattr(struct dentry
*dentry
, struct dentry
*upperdentry
,
348 const char *name
, const void *value
, size_t size
,
352 struct ovl_fs
*ofs
= dentry
->d_sb
->s_fs_info
;
357 err
= ovl_do_setxattr(upperdentry
, name
, value
, size
, 0);
359 if (err
== -EOPNOTSUPP
) {
360 pr_warn("overlayfs: cannot set %s xattr on upper\n", name
);
368 int ovl_set_impure(struct dentry
*dentry
, struct dentry
*upperdentry
)
372 if (ovl_test_flag(OVL_IMPURE
, d_inode(dentry
)))
376 * Do not fail when upper doesn't support xattrs.
377 * Upper inodes won't have origin nor redirect xattr anyway.
379 err
= ovl_check_setxattr(dentry
, upperdentry
, OVL_XATTR_IMPURE
,
382 ovl_set_flag(OVL_IMPURE
, d_inode(dentry
));
387 void ovl_set_flag(unsigned long flag
, struct inode
*inode
)
389 set_bit(flag
, &OVL_I(inode
)->flags
);
392 void ovl_clear_flag(unsigned long flag
, struct inode
*inode
)
394 clear_bit(flag
, &OVL_I(inode
)->flags
);
397 bool ovl_test_flag(unsigned long flag
, struct inode
*inode
)
399 return test_bit(flag
, &OVL_I(inode
)->flags
);
403 * Caller must hold a reference to inode to prevent it from being freed while
404 * it is marked inuse.
406 bool ovl_inuse_trylock(struct dentry
*dentry
)
408 struct inode
*inode
= d_inode(dentry
);
411 spin_lock(&inode
->i_lock
);
412 if (!(inode
->i_state
& I_OVL_INUSE
)) {
413 inode
->i_state
|= I_OVL_INUSE
;
416 spin_unlock(&inode
->i_lock
);
421 void ovl_inuse_unlock(struct dentry
*dentry
)
424 struct inode
*inode
= d_inode(dentry
);
426 spin_lock(&inode
->i_lock
);
427 WARN_ON(!(inode
->i_state
& I_OVL_INUSE
));
428 inode
->i_state
&= ~I_OVL_INUSE
;
429 spin_unlock(&inode
->i_lock
);
433 /* Called must hold OVL_I(inode)->oi_lock */
434 static void ovl_cleanup_index(struct dentry
*dentry
)
436 struct inode
*dir
= ovl_indexdir(dentry
->d_sb
)->d_inode
;
437 struct dentry
*lowerdentry
= ovl_dentry_lower(dentry
);
438 struct dentry
*upperdentry
= ovl_dentry_upper(dentry
);
439 struct dentry
*index
= NULL
;
444 err
= ovl_get_index_name(lowerdentry
, &name
);
448 inode
= d_inode(upperdentry
);
449 if (inode
->i_nlink
!= 1) {
450 pr_warn_ratelimited("overlayfs: cleanup linked index (%pd2, ino=%lu, nlink=%u)\n",
451 upperdentry
, inode
->i_ino
, inode
->i_nlink
);
453 * We either have a bug with persistent union nlink or a lower
454 * hardlink was added while overlay is mounted. Adding a lower
455 * hardlink and then unlinking all overlay hardlinks would drop
456 * overlay nlink to zero before all upper inodes are unlinked.
457 * As a safety measure, when that situation is detected, set
458 * the overlay nlink to the index inode nlink minus one for the
459 * index entry itself.
461 set_nlink(d_inode(dentry
), inode
->i_nlink
- 1);
462 ovl_set_nlink_upper(dentry
);
466 inode_lock_nested(dir
, I_MUTEX_PARENT
);
467 /* TODO: whiteout instead of cleanup to block future open by handle */
468 index
= lookup_one_len(name
.name
, ovl_indexdir(dentry
->d_sb
), name
.len
);
469 err
= PTR_ERR(index
);
471 err
= ovl_cleanup(dir
, index
);
481 pr_err("overlayfs: cleanup index of '%pd2' failed (%i)\n", dentry
, err
);
486 * Operations that change overlay inode and upper inode nlink need to be
487 * synchronized with copy up for persistent nlink accounting.
489 int ovl_nlink_start(struct dentry
*dentry
, bool *locked
)
491 struct ovl_inode
*oi
= OVL_I(d_inode(dentry
));
492 const struct cred
*old_cred
;
495 if (!d_inode(dentry
) || d_is_dir(dentry
))
499 * With inodes index is enabled, we store the union overlay nlink
500 * in an xattr on the index inode. When whiting out lower hardlinks
501 * we need to decrement the overlay persistent nlink, but before the
502 * first copy up, we have no upper index inode to store the xattr.
504 * As a workaround, before whiteout/rename over of a lower hardlink,
505 * copy up to create the upper index. Creating the upper index will
506 * initialize the overlay nlink, so it could be dropped if unlink
507 * or rename succeeds.
509 * TODO: implement metadata only index copy up when called with
510 * ovl_copy_up_flags(dentry, O_PATH).
512 if (ovl_indexdir(dentry
->d_sb
) && !ovl_dentry_has_upper_alias(dentry
) &&
513 d_inode(ovl_dentry_lower(dentry
))->i_nlink
> 1) {
514 err
= ovl_copy_up(dentry
);
519 err
= mutex_lock_interruptible(&oi
->lock
);
523 if (!ovl_test_flag(OVL_INDEX
, d_inode(dentry
)))
526 old_cred
= ovl_override_creds(dentry
->d_sb
);
528 * The overlay inode nlink should be incremented/decremented IFF the
529 * upper operation succeeds, along with nlink change of upper inode.
530 * Therefore, before link/unlink/rename, we store the union nlink
531 * value relative to the upper inode nlink in an upper inode xattr.
533 err
= ovl_set_nlink_upper(dentry
);
534 revert_creds(old_cred
);
538 mutex_unlock(&oi
->lock
);
545 void ovl_nlink_end(struct dentry
*dentry
, bool locked
)
548 if (ovl_test_flag(OVL_INDEX
, d_inode(dentry
)) &&
549 d_inode(dentry
)->i_nlink
== 0) {
550 const struct cred
*old_cred
;
552 old_cred
= ovl_override_creds(dentry
->d_sb
);
553 ovl_cleanup_index(dentry
);
554 revert_creds(old_cred
);
557 mutex_unlock(&OVL_I(d_inode(dentry
))->lock
);