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 inode *ovl_inode_upper(struct inode *inode)
162 struct dentry *upperdentry = ovl_upperdentry_dereference(OVL_I(inode));
164 return upperdentry ? d_inode(upperdentry) : NULL;
167 struct inode *ovl_inode_lower(struct inode *inode)
169 return OVL_I(inode)->lower;
172 struct inode *ovl_inode_real(struct inode *inode)
174 return ovl_inode_upper(inode) ?: ovl_inode_lower(inode);
178 struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
180 return OVL_I(d_inode(dentry))->cache;
183 void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
185 OVL_I(d_inode(dentry))->cache = cache;
188 bool ovl_dentry_is_opaque(struct dentry *dentry)
190 struct ovl_entry *oe = dentry->d_fsdata;
194 bool ovl_dentry_is_whiteout(struct dentry *dentry)
196 return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
199 void ovl_dentry_set_opaque(struct dentry *dentry)
201 struct ovl_entry *oe = dentry->d_fsdata;
207 * For hard links it's possible for ovl_dentry_upper() to return positive, while
208 * there's no actual upper alias for the inode. Copy up code needs to know
209 * about the existence of the upper alias, so it can't use ovl_dentry_upper().
211 bool ovl_dentry_has_upper_alias(struct dentry *dentry)
213 struct ovl_entry *oe = dentry->d_fsdata;
215 return oe->has_upper;
218 void ovl_dentry_set_upper_alias(struct dentry *dentry)
220 struct ovl_entry *oe = dentry->d_fsdata;
222 oe->has_upper = true;
225 bool ovl_redirect_dir(struct super_block *sb)
227 struct ovl_fs *ofs = sb->s_fs_info;
229 return ofs->config.redirect_dir && !ofs->noxattr;
232 const char *ovl_dentry_get_redirect(struct dentry *dentry)
234 return OVL_I(d_inode(dentry))->redirect;
237 void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect)
239 struct ovl_inode *oi = OVL_I(d_inode(dentry));
242 oi->redirect = redirect;
245 void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
246 struct dentry *lowerdentry)
249 OVL_I(inode)->__upperdentry = upperdentry;
251 OVL_I(inode)->lower = d_inode(lowerdentry);
253 ovl_copyattr(d_inode(upperdentry ?: lowerdentry), inode);
256 void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
258 struct inode *upperinode = d_inode(upperdentry);
260 WARN_ON(OVL_I(inode)->__upperdentry);
263 * Make sure upperdentry is consistent before making it visible
266 OVL_I(inode)->__upperdentry = upperdentry;
267 if (!S_ISDIR(upperinode->i_mode) && inode_unhashed(inode)) {
268 inode->i_private = upperinode;
269 __insert_inode_hash(inode, (unsigned long) upperinode);
273 void ovl_dentry_version_inc(struct dentry *dentry)
275 struct inode *inode = d_inode(dentry);
277 WARN_ON(!inode_is_locked(inode));
278 OVL_I(inode)->version++;
281 u64 ovl_dentry_version_get(struct dentry *dentry)
283 struct inode *inode = d_inode(dentry);
285 WARN_ON(!inode_is_locked(inode));
286 return OVL_I(inode)->version;
289 bool ovl_is_whiteout(struct dentry *dentry)
291 struct inode *inode = dentry->d_inode;
293 return inode && IS_WHITEOUT(inode);
296 struct file *ovl_path_open(struct path *path, int flags)
298 return dentry_open(path, flags | O_NOATIME, current_cred());
301 int ovl_copy_up_start(struct dentry *dentry)
303 struct ovl_inode *oi = OVL_I(d_inode(dentry));
306 err = mutex_lock_interruptible(&oi->lock);
307 if (!err && ovl_dentry_has_upper_alias(dentry)) {
308 err = 1; /* Already copied up */
309 mutex_unlock(&oi->lock);
315 void ovl_copy_up_end(struct dentry *dentry)
317 mutex_unlock(&OVL_I(d_inode(dentry))->lock);
320 bool ovl_check_dir_xattr(struct dentry *dentry, const char *name)
325 if (!d_is_dir(dentry))
328 res = vfs_getxattr(dentry, name, &val, 1);
329 if (res == 1 && val == 'y')
335 int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
336 const char *name, const void *value, size_t size,
340 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
345 err = ovl_do_setxattr(upperdentry, name, value, size, 0);
347 if (err == -EOPNOTSUPP) {
348 pr_warn("overlayfs: cannot set %s xattr on upper\n", name);
356 int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry)
360 if (ovl_test_flag(OVL_IMPURE, d_inode(dentry)))
364 * Do not fail when upper doesn't support xattrs.
365 * Upper inodes won't have origin nor redirect xattr anyway.
367 err = ovl_check_setxattr(dentry, upperdentry, OVL_XATTR_IMPURE,
370 ovl_set_flag(OVL_IMPURE, d_inode(dentry));
375 void ovl_set_flag(unsigned long flag, struct inode *inode)
377 set_bit(flag, &OVL_I(inode)->flags);
380 bool ovl_test_flag(unsigned long flag, struct inode *inode)
382 return test_bit(flag, &OVL_I(inode)->flags);
386 * Caller must hold a reference to inode to prevent it from being freed while
387 * it is marked inuse.
389 bool ovl_inuse_trylock(struct dentry *dentry)
391 struct inode *inode = d_inode(dentry);
394 spin_lock(&inode->i_lock);
395 if (!(inode->i_state & I_OVL_INUSE)) {
396 inode->i_state |= I_OVL_INUSE;
399 spin_unlock(&inode->i_lock);
404 void ovl_inuse_unlock(struct dentry *dentry)
407 struct inode *inode = d_inode(dentry);
409 spin_lock(&inode->i_lock);
410 WARN_ON(!(inode->i_state & I_OVL_INUSE));
411 inode->i_state &= ~I_OVL_INUSE;
412 spin_unlock(&inode->i_lock);
416 /* Called must hold OVL_I(inode)->oi_lock */
417 static void ovl_cleanup_index(struct dentry *dentry)
419 struct inode *dir = ovl_indexdir(dentry->d_sb)->d_inode;
420 struct dentry *lowerdentry = ovl_dentry_lower(dentry);
421 struct dentry *upperdentry = ovl_dentry_upper(dentry);
422 struct dentry *index = NULL;
427 err = ovl_get_index_name(lowerdentry, &name);
431 inode = d_inode(upperdentry);
432 if (inode->i_nlink != 1) {
433 pr_warn_ratelimited("overlayfs: cleanup linked index (%pd2, ino=%lu, nlink=%u)\n",
434 upperdentry, inode->i_ino, inode->i_nlink);
436 * We either have a bug with persistent union nlink or a lower
437 * hardlink was added while overlay is mounted. Adding a lower
438 * hardlink and then unlinking all overlay hardlinks would drop
439 * overlay nlink to zero before all upper inodes are unlinked.
440 * As a safety measure, when that situation is detected, set
441 * the overlay nlink to the index inode nlink minus one for the
442 * index entry itself.
444 set_nlink(d_inode(dentry), inode->i_nlink - 1);
445 ovl_set_nlink_upper(dentry);
449 inode_lock_nested(dir, I_MUTEX_PARENT);
450 /* TODO: whiteout instead of cleanup to block future open by handle */
451 index = lookup_one_len(name.name, ovl_indexdir(dentry->d_sb), name.len);
452 err = PTR_ERR(index);
454 err = ovl_cleanup(dir, index);
464 pr_err("overlayfs: cleanup index of '%pd2' failed (%i)\n", dentry, err);
469 * Operations that change overlay inode and upper inode nlink need to be
470 * synchronized with copy up for persistent nlink accounting.
472 int ovl_nlink_start(struct dentry *dentry, bool *locked)
474 struct ovl_inode *oi = OVL_I(d_inode(dentry));
475 const struct cred *old_cred;
478 if (!d_inode(dentry) || d_is_dir(dentry))
482 * With inodes index is enabled, we store the union overlay nlink
483 * in an xattr on the index inode. When whiting out lower hardlinks
484 * we need to decrement the overlay persistent nlink, but before the
485 * first copy up, we have no upper index inode to store the xattr.
487 * As a workaround, before whiteout/rename over of a lower hardlink,
488 * copy up to create the upper index. Creating the upper index will
489 * initialize the overlay nlink, so it could be dropped if unlink
490 * or rename succeeds.
492 * TODO: implement metadata only index copy up when called with
493 * ovl_copy_up_flags(dentry, O_PATH).
495 if (ovl_indexdir(dentry->d_sb) && !ovl_dentry_has_upper_alias(dentry) &&
496 d_inode(ovl_dentry_lower(dentry))->i_nlink > 1) {
497 err = ovl_copy_up(dentry);
502 err = mutex_lock_interruptible(&oi->lock);
506 if (!ovl_test_flag(OVL_INDEX, d_inode(dentry)))
509 old_cred = ovl_override_creds(dentry->d_sb);
511 * The overlay inode nlink should be incremented/decremented IFF the
512 * upper operation succeeds, along with nlink change of upper inode.
513 * Therefore, before link/unlink/rename, we store the union nlink
514 * value relative to the upper inode nlink in an upper inode xattr.
516 err = ovl_set_nlink_upper(dentry);
517 revert_creds(old_cred);
521 mutex_unlock(&oi->lock);
528 void ovl_nlink_end(struct dentry *dentry, bool locked)
531 if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) &&
532 d_inode(dentry)->i_nlink == 0) {
533 const struct cred *old_cred;
535 old_cred = ovl_override_creds(dentry->d_sb);
536 ovl_cleanup_index(dentry);
537 revert_creds(old_cred);
540 mutex_unlock(&OVL_I(d_inode(dentry))->lock);