1 // SPDX-License-Identifier: GPL-2.0-only
4 * Library for filesystems writers.
7 #include <linux/blkdev.h>
8 #include <linux/export.h>
9 #include <linux/pagemap.h>
10 #include <linux/slab.h>
11 #include <linux/cred.h>
12 #include <linux/mount.h>
13 #include <linux/vfs.h>
14 #include <linux/quotaops.h>
15 #include <linux/mutex.h>
16 #include <linux/namei.h>
17 #include <linux/exportfs.h>
18 #include <linux/iversion.h>
19 #include <linux/writeback.h>
20 #include <linux/buffer_head.h> /* sync_mapping_buffers */
21 #include <linux/fs_context.h>
22 #include <linux/pseudo_fs.h>
23 #include <linux/fsnotify.h>
24 #include <linux/unicode.h>
25 #include <linux/fscrypt.h>
27 #include <linux/uaccess.h>
31 int simple_getattr(struct mnt_idmap *idmap, const struct path *path,
32 struct kstat *stat, u32 request_mask,
33 unsigned int query_flags)
35 struct inode *inode = d_inode(path->dentry);
36 generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
37 stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
40 EXPORT_SYMBOL(simple_getattr);
42 int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
44 u64 id = huge_encode_dev(dentry->d_sb->s_dev);
46 buf->f_fsid = u64_to_fsid(id);
47 buf->f_type = dentry->d_sb->s_magic;
48 buf->f_bsize = PAGE_SIZE;
49 buf->f_namelen = NAME_MAX;
52 EXPORT_SYMBOL(simple_statfs);
55 * Retaining negative dentries for an in-memory filesystem just wastes
56 * memory and lookup time: arrange for them to be deleted immediately.
58 int always_delete_dentry(const struct dentry *dentry)
62 EXPORT_SYMBOL(always_delete_dentry);
64 const struct dentry_operations simple_dentry_operations = {
65 .d_delete = always_delete_dentry,
67 EXPORT_SYMBOL(simple_dentry_operations);
70 * Lookup the data. This is trivial - if the dentry didn't already
71 * exist, we know it is negative. Set d_op to delete negative dentries.
73 struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
75 if (dentry->d_name.len > NAME_MAX)
76 return ERR_PTR(-ENAMETOOLONG);
77 if (!dentry->d_sb->s_d_op)
78 d_set_d_op(dentry, &simple_dentry_operations);
82 EXPORT_SYMBOL(simple_lookup);
84 int dcache_dir_open(struct inode *inode, struct file *file)
86 file->private_data = d_alloc_cursor(file->f_path.dentry);
88 return file->private_data ? 0 : -ENOMEM;
90 EXPORT_SYMBOL(dcache_dir_open);
92 int dcache_dir_close(struct inode *inode, struct file *file)
94 dput(file->private_data);
97 EXPORT_SYMBOL(dcache_dir_close);
99 /* parent is locked at least shared */
101 * Returns an element of siblings' list.
102 * We are looking for <count>th positive after <p>; if
103 * found, dentry is grabbed and returned to caller.
104 * If no such element exists, NULL is returned.
106 static struct dentry *scan_positives(struct dentry *cursor,
111 struct dentry *dentry = cursor->d_parent, *found = NULL;
113 spin_lock(&dentry->d_lock);
114 while ((p = p->next) != &dentry->d_subdirs) {
115 struct dentry *d = list_entry(p, struct dentry, d_child);
116 // we must at least skip cursors, to avoid livelocks
117 if (d->d_flags & DCACHE_DENTRY_CURSOR)
119 if (simple_positive(d) && !--count) {
120 spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
121 if (simple_positive(d))
122 found = dget_dlock(d);
123 spin_unlock(&d->d_lock);
128 if (need_resched()) {
129 list_move(&cursor->d_child, p);
130 p = &cursor->d_child;
131 spin_unlock(&dentry->d_lock);
133 spin_lock(&dentry->d_lock);
136 spin_unlock(&dentry->d_lock);
141 loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
143 struct dentry *dentry = file->f_path.dentry;
146 offset += file->f_pos;
155 if (offset != file->f_pos) {
156 struct dentry *cursor = file->private_data;
157 struct dentry *to = NULL;
159 inode_lock_shared(dentry->d_inode);
162 to = scan_positives(cursor, &dentry->d_subdirs,
164 spin_lock(&dentry->d_lock);
166 list_move(&cursor->d_child, &to->d_child);
168 list_del_init(&cursor->d_child);
169 spin_unlock(&dentry->d_lock);
172 file->f_pos = offset;
174 inode_unlock_shared(dentry->d_inode);
178 EXPORT_SYMBOL(dcache_dir_lseek);
181 * Directory is locked and all positive dentries in it are safe, since
182 * for ramfs-type trees they can't go away without unlink() or rmdir(),
183 * both impossible due to the lock on directory.
186 int dcache_readdir(struct file *file, struct dir_context *ctx)
188 struct dentry *dentry = file->f_path.dentry;
189 struct dentry *cursor = file->private_data;
190 struct list_head *anchor = &dentry->d_subdirs;
191 struct dentry *next = NULL;
194 if (!dir_emit_dots(file, ctx))
199 else if (!list_empty(&cursor->d_child))
200 p = &cursor->d_child;
204 while ((next = scan_positives(cursor, p, 1, next)) != NULL) {
205 if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
206 d_inode(next)->i_ino,
207 fs_umode_to_dtype(d_inode(next)->i_mode)))
212 spin_lock(&dentry->d_lock);
214 list_move_tail(&cursor->d_child, &next->d_child);
216 list_del_init(&cursor->d_child);
217 spin_unlock(&dentry->d_lock);
222 EXPORT_SYMBOL(dcache_readdir);
224 ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
228 EXPORT_SYMBOL(generic_read_dir);
230 const struct file_operations simple_dir_operations = {
231 .open = dcache_dir_open,
232 .release = dcache_dir_close,
233 .llseek = dcache_dir_lseek,
234 .read = generic_read_dir,
235 .iterate_shared = dcache_readdir,
238 EXPORT_SYMBOL(simple_dir_operations);
240 const struct inode_operations simple_dir_inode_operations = {
241 .lookup = simple_lookup,
243 EXPORT_SYMBOL(simple_dir_inode_operations);
245 static void offset_set(struct dentry *dentry, u32 offset)
247 dentry->d_fsdata = (void *)((uintptr_t)(offset));
250 static u32 dentry2offset(struct dentry *dentry)
252 return (u32)((uintptr_t)(dentry->d_fsdata));
255 static struct lock_class_key simple_offset_xa_lock;
258 * simple_offset_init - initialize an offset_ctx
259 * @octx: directory offset map to be initialized
262 void simple_offset_init(struct offset_ctx *octx)
264 xa_init_flags(&octx->xa, XA_FLAGS_ALLOC1);
265 lockdep_set_class(&octx->xa.xa_lock, &simple_offset_xa_lock);
267 /* 0 is '.', 1 is '..', so always start with offset 2 */
268 octx->next_offset = 2;
272 * simple_offset_add - Add an entry to a directory's offset map
273 * @octx: directory offset ctx to be updated
274 * @dentry: new dentry being added
276 * Returns zero on success. @so_ctx and the dentry offset are updated.
277 * Otherwise, a negative errno value is returned.
279 int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry)
281 static const struct xa_limit limit = XA_LIMIT(2, U32_MAX);
285 if (dentry2offset(dentry) != 0)
288 ret = xa_alloc_cyclic(&octx->xa, &offset, dentry, limit,
289 &octx->next_offset, GFP_KERNEL);
293 offset_set(dentry, offset);
298 * simple_offset_remove - Remove an entry to a directory's offset map
299 * @octx: directory offset ctx to be updated
300 * @dentry: dentry being removed
303 void simple_offset_remove(struct offset_ctx *octx, struct dentry *dentry)
307 offset = dentry2offset(dentry);
311 xa_erase(&octx->xa, offset);
312 offset_set(dentry, 0);
316 * simple_offset_rename_exchange - exchange rename with directory offsets
317 * @old_dir: parent of dentry being moved
318 * @old_dentry: dentry being moved
319 * @new_dir: destination parent
320 * @new_dentry: destination dentry
322 * Returns zero on success. Otherwise a negative errno is returned and the
323 * rename is rolled back.
325 int simple_offset_rename_exchange(struct inode *old_dir,
326 struct dentry *old_dentry,
327 struct inode *new_dir,
328 struct dentry *new_dentry)
330 struct offset_ctx *old_ctx = old_dir->i_op->get_offset_ctx(old_dir);
331 struct offset_ctx *new_ctx = new_dir->i_op->get_offset_ctx(new_dir);
332 u32 old_index = dentry2offset(old_dentry);
333 u32 new_index = dentry2offset(new_dentry);
336 simple_offset_remove(old_ctx, old_dentry);
337 simple_offset_remove(new_ctx, new_dentry);
339 ret = simple_offset_add(new_ctx, old_dentry);
343 ret = simple_offset_add(old_ctx, new_dentry);
345 simple_offset_remove(new_ctx, old_dentry);
349 ret = simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry);
351 simple_offset_remove(new_ctx, old_dentry);
352 simple_offset_remove(old_ctx, new_dentry);
358 offset_set(old_dentry, old_index);
359 xa_store(&old_ctx->xa, old_index, old_dentry, GFP_KERNEL);
360 offset_set(new_dentry, new_index);
361 xa_store(&new_ctx->xa, new_index, new_dentry, GFP_KERNEL);
366 * simple_offset_destroy - Release offset map
367 * @octx: directory offset ctx that is about to be destroyed
369 * During fs teardown (eg. umount), a directory's offset map might still
370 * contain entries. xa_destroy() cleans out anything that remains.
372 void simple_offset_destroy(struct offset_ctx *octx)
374 xa_destroy(&octx->xa);
378 * offset_dir_llseek - Advance the read position of a directory descriptor
379 * @file: an open directory whose position is to be updated
380 * @offset: a byte offset
381 * @whence: enumerator describing the starting position for this update
383 * SEEK_END, SEEK_DATA, and SEEK_HOLE are not supported for directories.
385 * Returns the updated read position if successful; otherwise a
386 * negative errno is returned and the read position remains unchanged.
388 static loff_t offset_dir_llseek(struct file *file, loff_t offset, int whence)
392 offset += file->f_pos;
402 /* In this case, ->private_data is protected by f_pos_lock */
403 file->private_data = NULL;
404 return vfs_setpos(file, offset, U32_MAX);
407 static struct dentry *offset_find_next(struct xa_state *xas)
409 struct dentry *child, *found = NULL;
412 child = xas_next_entry(xas, U32_MAX);
415 spin_lock(&child->d_lock);
416 if (simple_positive(child))
417 found = dget_dlock(child);
418 spin_unlock(&child->d_lock);
424 static bool offset_dir_emit(struct dir_context *ctx, struct dentry *dentry)
426 u32 offset = dentry2offset(dentry);
427 struct inode *inode = d_inode(dentry);
429 return ctx->actor(ctx, dentry->d_name.name, dentry->d_name.len, offset,
430 inode->i_ino, fs_umode_to_dtype(inode->i_mode));
433 static void *offset_iterate_dir(struct inode *inode, struct dir_context *ctx)
435 struct offset_ctx *so_ctx = inode->i_op->get_offset_ctx(inode);
436 XA_STATE(xas, &so_ctx->xa, ctx->pos);
437 struct dentry *dentry;
440 dentry = offset_find_next(&xas);
442 return ERR_PTR(-ENOENT);
444 if (!offset_dir_emit(ctx, dentry)) {
450 ctx->pos = xas.xa_index + 1;
456 * offset_readdir - Emit entries starting at offset @ctx->pos
457 * @file: an open directory to iterate over
458 * @ctx: directory iteration context
460 * Caller must hold @file's i_rwsem to prevent insertion or removal of
461 * entries during this call.
463 * On entry, @ctx->pos contains an offset that represents the first entry
464 * to be read from the directory.
466 * The operation continues until there are no more entries to read, or
467 * until the ctx->actor indicates there is no more space in the caller's
470 * On return, @ctx->pos contains an offset that will read the next entry
471 * in this directory when offset_readdir() is called again with @ctx.
476 static int offset_readdir(struct file *file, struct dir_context *ctx)
478 struct dentry *dir = file->f_path.dentry;
480 lockdep_assert_held(&d_inode(dir)->i_rwsem);
482 if (!dir_emit_dots(file, ctx))
485 /* In this case, ->private_data is protected by f_pos_lock */
487 file->private_data = NULL;
488 else if (file->private_data == ERR_PTR(-ENOENT))
490 file->private_data = offset_iterate_dir(d_inode(dir), ctx);
494 const struct file_operations simple_offset_dir_operations = {
495 .llseek = offset_dir_llseek,
496 .iterate_shared = offset_readdir,
497 .read = generic_read_dir,
501 static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev)
503 struct dentry *child = NULL;
504 struct list_head *p = prev ? &prev->d_child : &parent->d_subdirs;
506 spin_lock(&parent->d_lock);
507 while ((p = p->next) != &parent->d_subdirs) {
508 struct dentry *d = container_of(p, struct dentry, d_child);
509 if (simple_positive(d)) {
510 spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
511 if (simple_positive(d))
512 child = dget_dlock(d);
513 spin_unlock(&d->d_lock);
518 spin_unlock(&parent->d_lock);
523 void simple_recursive_removal(struct dentry *dentry,
524 void (*callback)(struct dentry *))
526 struct dentry *this = dget(dentry);
528 struct dentry *victim = NULL, *child;
529 struct inode *inode = this->d_inode;
533 inode->i_flags |= S_DEAD;
534 while ((child = find_next_child(this, victim)) == NULL) {
536 // update metadata while it's still locked
537 inode_set_ctime_current(inode);
541 this = this->d_parent;
542 inode = this->d_inode;
544 if (simple_positive(victim)) {
545 d_invalidate(victim); // avoid lost mounts
546 if (d_is_dir(victim))
547 fsnotify_rmdir(inode, victim);
549 fsnotify_unlink(inode, victim);
552 dput(victim); // unpin it
554 if (victim == dentry) {
555 inode_set_mtime_to_ts(inode,
556 inode_set_ctime_current(inode));
557 if (d_is_dir(dentry))
568 EXPORT_SYMBOL(simple_recursive_removal);
570 static const struct super_operations simple_super_operations = {
571 .statfs = simple_statfs,
574 static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc)
576 struct pseudo_fs_context *ctx = fc->fs_private;
579 s->s_maxbytes = MAX_LFS_FILESIZE;
580 s->s_blocksize = PAGE_SIZE;
581 s->s_blocksize_bits = PAGE_SHIFT;
582 s->s_magic = ctx->magic;
583 s->s_op = ctx->ops ?: &simple_super_operations;
584 s->s_xattr = ctx->xattr;
591 * since this is the first inode, make it number 1. New inodes created
592 * after this must take care not to collide with it (by passing
593 * max_reserved of 1 to iunique).
596 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
597 simple_inode_init_ts(root);
598 s->s_root = d_make_root(root);
601 s->s_d_op = ctx->dops;
605 static int pseudo_fs_get_tree(struct fs_context *fc)
607 return get_tree_nodev(fc, pseudo_fs_fill_super);
610 static void pseudo_fs_free(struct fs_context *fc)
612 kfree(fc->fs_private);
615 static const struct fs_context_operations pseudo_fs_context_ops = {
616 .free = pseudo_fs_free,
617 .get_tree = pseudo_fs_get_tree,
621 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
622 * will never be mountable)
624 struct pseudo_fs_context *init_pseudo(struct fs_context *fc,
627 struct pseudo_fs_context *ctx;
629 ctx = kzalloc(sizeof(struct pseudo_fs_context), GFP_KERNEL);
632 fc->fs_private = ctx;
633 fc->ops = &pseudo_fs_context_ops;
634 fc->sb_flags |= SB_NOUSER;
639 EXPORT_SYMBOL(init_pseudo);
641 int simple_open(struct inode *inode, struct file *file)
643 if (inode->i_private)
644 file->private_data = inode->i_private;
647 EXPORT_SYMBOL(simple_open);
649 int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
651 struct inode *inode = d_inode(old_dentry);
653 inode_set_mtime_to_ts(dir,
654 inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
658 d_instantiate(dentry, inode);
661 EXPORT_SYMBOL(simple_link);
663 int simple_empty(struct dentry *dentry)
665 struct dentry *child;
668 spin_lock(&dentry->d_lock);
669 list_for_each_entry(child, &dentry->d_subdirs, d_child) {
670 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
671 if (simple_positive(child)) {
672 spin_unlock(&child->d_lock);
675 spin_unlock(&child->d_lock);
679 spin_unlock(&dentry->d_lock);
682 EXPORT_SYMBOL(simple_empty);
684 int simple_unlink(struct inode *dir, struct dentry *dentry)
686 struct inode *inode = d_inode(dentry);
688 inode_set_mtime_to_ts(dir,
689 inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
694 EXPORT_SYMBOL(simple_unlink);
696 int simple_rmdir(struct inode *dir, struct dentry *dentry)
698 if (!simple_empty(dentry))
701 drop_nlink(d_inode(dentry));
702 simple_unlink(dir, dentry);
706 EXPORT_SYMBOL(simple_rmdir);
709 * simple_rename_timestamp - update the various inode timestamps for rename
710 * @old_dir: old parent directory
711 * @old_dentry: dentry that is being renamed
712 * @new_dir: new parent directory
713 * @new_dentry: target for rename
715 * POSIX mandates that the old and new parent directories have their ctime and
716 * mtime updated, and that inodes of @old_dentry and @new_dentry (if any), have
717 * their ctime updated.
719 void simple_rename_timestamp(struct inode *old_dir, struct dentry *old_dentry,
720 struct inode *new_dir, struct dentry *new_dentry)
722 struct inode *newino = d_inode(new_dentry);
724 inode_set_mtime_to_ts(old_dir, inode_set_ctime_current(old_dir));
725 if (new_dir != old_dir)
726 inode_set_mtime_to_ts(new_dir,
727 inode_set_ctime_current(new_dir));
728 inode_set_ctime_current(d_inode(old_dentry));
730 inode_set_ctime_current(newino);
732 EXPORT_SYMBOL_GPL(simple_rename_timestamp);
734 int simple_rename_exchange(struct inode *old_dir, struct dentry *old_dentry,
735 struct inode *new_dir, struct dentry *new_dentry)
737 bool old_is_dir = d_is_dir(old_dentry);
738 bool new_is_dir = d_is_dir(new_dentry);
740 if (old_dir != new_dir && old_is_dir != new_is_dir) {
749 simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
752 EXPORT_SYMBOL_GPL(simple_rename_exchange);
754 int simple_rename(struct mnt_idmap *idmap, struct inode *old_dir,
755 struct dentry *old_dentry, struct inode *new_dir,
756 struct dentry *new_dentry, unsigned int flags)
758 int they_are_dirs = d_is_dir(old_dentry);
760 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
763 if (flags & RENAME_EXCHANGE)
764 return simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry);
766 if (!simple_empty(new_dentry))
769 if (d_really_is_positive(new_dentry)) {
770 simple_unlink(new_dir, new_dentry);
772 drop_nlink(d_inode(new_dentry));
775 } else if (they_are_dirs) {
780 simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
783 EXPORT_SYMBOL(simple_rename);
786 * simple_setattr - setattr for simple filesystem
787 * @idmap: idmap of the target mount
789 * @iattr: iattr structure
791 * Returns 0 on success, -error on failure.
793 * simple_setattr is a simple ->setattr implementation without a proper
794 * implementation of size changes.
796 * It can either be used for in-memory filesystems or special files
797 * on simple regular filesystems. Anything that needs to change on-disk
798 * or wire state on size changes needs its own setattr method.
800 int simple_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
803 struct inode *inode = d_inode(dentry);
806 error = setattr_prepare(idmap, dentry, iattr);
810 if (iattr->ia_valid & ATTR_SIZE)
811 truncate_setsize(inode, iattr->ia_size);
812 setattr_copy(idmap, inode, iattr);
813 mark_inode_dirty(inode);
816 EXPORT_SYMBOL(simple_setattr);
818 static int simple_read_folio(struct file *file, struct folio *folio)
820 folio_zero_range(folio, 0, folio_size(folio));
821 flush_dcache_folio(folio);
822 folio_mark_uptodate(folio);
827 int simple_write_begin(struct file *file, struct address_space *mapping,
828 loff_t pos, unsigned len,
829 struct page **pagep, void **fsdata)
833 folio = __filemap_get_folio(mapping, pos / PAGE_SIZE, FGP_WRITEBEGIN,
834 mapping_gfp_mask(mapping));
836 return PTR_ERR(folio);
838 *pagep = &folio->page;
840 if (!folio_test_uptodate(folio) && (len != folio_size(folio))) {
841 size_t from = offset_in_folio(folio, pos);
843 folio_zero_segments(folio, 0, from,
844 from + len, folio_size(folio));
848 EXPORT_SYMBOL(simple_write_begin);
851 * simple_write_end - .write_end helper for non-block-device FSes
852 * @file: See .write_end of address_space_operations
860 * simple_write_end does the minimum needed for updating a page after writing is
861 * done. It has the same API signature as the .write_end of
862 * address_space_operations vector. So it can just be set onto .write_end for
863 * FSes that don't need any other processing. i_mutex is assumed to be held.
864 * Block based filesystems should use generic_write_end().
865 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
866 * is not called, so a filesystem that actually does store data in .write_inode
867 * should extend on what's done here with a call to mark_inode_dirty() in the
868 * case that i_size has changed.
870 * Use *ONLY* with simple_read_folio()
872 static int simple_write_end(struct file *file, struct address_space *mapping,
873 loff_t pos, unsigned len, unsigned copied,
874 struct page *page, void *fsdata)
876 struct folio *folio = page_folio(page);
877 struct inode *inode = folio->mapping->host;
878 loff_t last_pos = pos + copied;
880 /* zero the stale part of the folio if we did a short copy */
881 if (!folio_test_uptodate(folio)) {
883 size_t from = offset_in_folio(folio, pos);
885 folio_zero_range(folio, from + copied, len - copied);
887 folio_mark_uptodate(folio);
890 * No need to use i_size_read() here, the i_size
891 * cannot change under us because we hold the i_mutex.
893 if (last_pos > inode->i_size)
894 i_size_write(inode, last_pos);
896 folio_mark_dirty(folio);
904 * Provides ramfs-style behavior: data in the pagecache, but no writeback.
906 const struct address_space_operations ram_aops = {
907 .read_folio = simple_read_folio,
908 .write_begin = simple_write_begin,
909 .write_end = simple_write_end,
910 .dirty_folio = noop_dirty_folio,
912 EXPORT_SYMBOL(ram_aops);
915 * the inodes created here are not hashed. If you use iunique to generate
916 * unique inode values later for this filesystem, then you must take care
917 * to pass it an appropriate max_reserved value to avoid collisions.
919 int simple_fill_super(struct super_block *s, unsigned long magic,
920 const struct tree_descr *files)
924 struct dentry *dentry;
927 s->s_blocksize = PAGE_SIZE;
928 s->s_blocksize_bits = PAGE_SHIFT;
930 s->s_op = &simple_super_operations;
933 inode = new_inode(s);
937 * because the root inode is 1, the files array must not contain an
941 inode->i_mode = S_IFDIR | 0755;
942 simple_inode_init_ts(inode);
943 inode->i_op = &simple_dir_inode_operations;
944 inode->i_fop = &simple_dir_operations;
946 root = d_make_root(inode);
949 for (i = 0; !files->name || files->name[0]; i++, files++) {
953 /* warn if it tries to conflict with the root inode */
954 if (unlikely(i == 1))
955 printk(KERN_WARNING "%s: %s passed in a files array"
956 "with an index of 1!\n", __func__,
959 dentry = d_alloc_name(root, files->name);
962 inode = new_inode(s);
967 inode->i_mode = S_IFREG | files->mode;
968 simple_inode_init_ts(inode);
969 inode->i_fop = files->ops;
971 d_add(dentry, inode);
977 shrink_dcache_parent(root);
981 EXPORT_SYMBOL(simple_fill_super);
983 static DEFINE_SPINLOCK(pin_fs_lock);
985 int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
987 struct vfsmount *mnt = NULL;
988 spin_lock(&pin_fs_lock);
989 if (unlikely(!*mount)) {
990 spin_unlock(&pin_fs_lock);
991 mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
994 spin_lock(&pin_fs_lock);
1000 spin_unlock(&pin_fs_lock);
1004 EXPORT_SYMBOL(simple_pin_fs);
1006 void simple_release_fs(struct vfsmount **mount, int *count)
1008 struct vfsmount *mnt;
1009 spin_lock(&pin_fs_lock);
1013 spin_unlock(&pin_fs_lock);
1016 EXPORT_SYMBOL(simple_release_fs);
1019 * simple_read_from_buffer - copy data from the buffer to user space
1020 * @to: the user space buffer to read to
1021 * @count: the maximum number of bytes to read
1022 * @ppos: the current position in the buffer
1023 * @from: the buffer to read from
1024 * @available: the size of the buffer
1026 * The simple_read_from_buffer() function reads up to @count bytes from the
1027 * buffer @from at offset @ppos into the user space address starting at @to.
1029 * On success, the number of bytes read is returned and the offset @ppos is
1030 * advanced by this number, or negative value is returned on error.
1032 ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
1033 const void *from, size_t available)
1040 if (pos >= available || !count)
1042 if (count > available - pos)
1043 count = available - pos;
1044 ret = copy_to_user(to, from + pos, count);
1048 *ppos = pos + count;
1051 EXPORT_SYMBOL(simple_read_from_buffer);
1054 * simple_write_to_buffer - copy data from user space to the buffer
1055 * @to: the buffer to write to
1056 * @available: the size of the buffer
1057 * @ppos: the current position in the buffer
1058 * @from: the user space buffer to read from
1059 * @count: the maximum number of bytes to read
1061 * The simple_write_to_buffer() function reads up to @count bytes from the user
1062 * space address starting at @from into the buffer @to at offset @ppos.
1064 * On success, the number of bytes written is returned and the offset @ppos is
1065 * advanced by this number, or negative value is returned on error.
1067 ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
1068 const void __user *from, size_t count)
1075 if (pos >= available || !count)
1077 if (count > available - pos)
1078 count = available - pos;
1079 res = copy_from_user(to + pos, from, count);
1083 *ppos = pos + count;
1086 EXPORT_SYMBOL(simple_write_to_buffer);
1089 * memory_read_from_buffer - copy data from the buffer
1090 * @to: the kernel space buffer to read to
1091 * @count: the maximum number of bytes to read
1092 * @ppos: the current position in the buffer
1093 * @from: the buffer to read from
1094 * @available: the size of the buffer
1096 * The memory_read_from_buffer() function reads up to @count bytes from the
1097 * buffer @from at offset @ppos into the kernel space address starting at @to.
1099 * On success, the number of bytes read is returned and the offset @ppos is
1100 * advanced by this number, or negative value is returned on error.
1102 ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
1103 const void *from, size_t available)
1109 if (pos >= available)
1111 if (count > available - pos)
1112 count = available - pos;
1113 memcpy(to, from + pos, count);
1114 *ppos = pos + count;
1118 EXPORT_SYMBOL(memory_read_from_buffer);
1121 * Transaction based IO.
1122 * The file expects a single write which triggers the transaction, and then
1123 * possibly a read which collects the result - which is stored in a
1124 * file-local buffer.
1127 void simple_transaction_set(struct file *file, size_t n)
1129 struct simple_transaction_argresp *ar = file->private_data;
1131 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
1134 * The barrier ensures that ar->size will really remain zero until
1135 * ar->data is ready for reading.
1140 EXPORT_SYMBOL(simple_transaction_set);
1142 char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
1144 struct simple_transaction_argresp *ar;
1145 static DEFINE_SPINLOCK(simple_transaction_lock);
1147 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
1148 return ERR_PTR(-EFBIG);
1150 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
1152 return ERR_PTR(-ENOMEM);
1154 spin_lock(&simple_transaction_lock);
1156 /* only one write allowed per open */
1157 if (file->private_data) {
1158 spin_unlock(&simple_transaction_lock);
1159 free_page((unsigned long)ar);
1160 return ERR_PTR(-EBUSY);
1163 file->private_data = ar;
1165 spin_unlock(&simple_transaction_lock);
1167 if (copy_from_user(ar->data, buf, size))
1168 return ERR_PTR(-EFAULT);
1172 EXPORT_SYMBOL(simple_transaction_get);
1174 ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
1176 struct simple_transaction_argresp *ar = file->private_data;
1180 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
1182 EXPORT_SYMBOL(simple_transaction_read);
1184 int simple_transaction_release(struct inode *inode, struct file *file)
1186 free_page((unsigned long)file->private_data);
1189 EXPORT_SYMBOL(simple_transaction_release);
1191 /* Simple attribute files */
1193 struct simple_attr {
1194 int (*get)(void *, u64 *);
1195 int (*set)(void *, u64);
1196 char get_buf[24]; /* enough to store a u64 and "\n\0" */
1199 const char *fmt; /* format for read operation */
1200 struct mutex mutex; /* protects access to these buffers */
1203 /* simple_attr_open is called by an actual attribute open file operation
1204 * to set the attribute specific access operations. */
1205 int simple_attr_open(struct inode *inode, struct file *file,
1206 int (*get)(void *, u64 *), int (*set)(void *, u64),
1209 struct simple_attr *attr;
1211 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
1217 attr->data = inode->i_private;
1219 mutex_init(&attr->mutex);
1221 file->private_data = attr;
1223 return nonseekable_open(inode, file);
1225 EXPORT_SYMBOL_GPL(simple_attr_open);
1227 int simple_attr_release(struct inode *inode, struct file *file)
1229 kfree(file->private_data);
1232 EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
1234 /* read from the buffer that is filled with the get function */
1235 ssize_t simple_attr_read(struct file *file, char __user *buf,
1236 size_t len, loff_t *ppos)
1238 struct simple_attr *attr;
1242 attr = file->private_data;
1247 ret = mutex_lock_interruptible(&attr->mutex);
1251 if (*ppos && attr->get_buf[0]) {
1252 /* continued read */
1253 size = strlen(attr->get_buf);
1257 ret = attr->get(attr->data, &val);
1261 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
1262 attr->fmt, (unsigned long long)val);
1265 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
1267 mutex_unlock(&attr->mutex);
1270 EXPORT_SYMBOL_GPL(simple_attr_read);
1272 /* interpret the buffer as a number to call the set function with */
1273 static ssize_t simple_attr_write_xsigned(struct file *file, const char __user *buf,
1274 size_t len, loff_t *ppos, bool is_signed)
1276 struct simple_attr *attr;
1277 unsigned long long val;
1281 attr = file->private_data;
1285 ret = mutex_lock_interruptible(&attr->mutex);
1290 size = min(sizeof(attr->set_buf) - 1, len);
1291 if (copy_from_user(attr->set_buf, buf, size))
1294 attr->set_buf[size] = '\0';
1296 ret = kstrtoll(attr->set_buf, 0, &val);
1298 ret = kstrtoull(attr->set_buf, 0, &val);
1301 ret = attr->set(attr->data, val);
1303 ret = len; /* on success, claim we got the whole input */
1305 mutex_unlock(&attr->mutex);
1309 ssize_t simple_attr_write(struct file *file, const char __user *buf,
1310 size_t len, loff_t *ppos)
1312 return simple_attr_write_xsigned(file, buf, len, ppos, false);
1314 EXPORT_SYMBOL_GPL(simple_attr_write);
1316 ssize_t simple_attr_write_signed(struct file *file, const char __user *buf,
1317 size_t len, loff_t *ppos)
1319 return simple_attr_write_xsigned(file, buf, len, ppos, true);
1321 EXPORT_SYMBOL_GPL(simple_attr_write_signed);
1324 * generic_encode_ino32_fh - generic export_operations->encode_fh function
1325 * @inode: the object to encode
1326 * @fh: where to store the file handle fragment
1327 * @max_len: maximum length to store there (in 4 byte units)
1328 * @parent: parent directory inode, if wanted
1330 * This generic encode_fh function assumes that the 32 inode number
1331 * is suitable for locating an inode, and that the generation number
1332 * can be used to check that it is still valid. It places them in the
1333 * filehandle fragment where export_decode_fh expects to find them.
1335 int generic_encode_ino32_fh(struct inode *inode, __u32 *fh, int *max_len,
1336 struct inode *parent)
1338 struct fid *fid = (void *)fh;
1340 int type = FILEID_INO32_GEN;
1342 if (parent && (len < 4)) {
1344 return FILEID_INVALID;
1345 } else if (len < 2) {
1347 return FILEID_INVALID;
1351 fid->i32.ino = inode->i_ino;
1352 fid->i32.gen = inode->i_generation;
1354 fid->i32.parent_ino = parent->i_ino;
1355 fid->i32.parent_gen = parent->i_generation;
1357 type = FILEID_INO32_GEN_PARENT;
1362 EXPORT_SYMBOL_GPL(generic_encode_ino32_fh);
1365 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
1366 * @sb: filesystem to do the file handle conversion on
1367 * @fid: file handle to convert
1368 * @fh_len: length of the file handle in bytes
1369 * @fh_type: type of file handle
1370 * @get_inode: filesystem callback to retrieve inode
1372 * This function decodes @fid as long as it has one of the well-known
1373 * Linux filehandle types and calls @get_inode on it to retrieve the
1374 * inode for the object specified in the file handle.
1376 struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
1377 int fh_len, int fh_type, struct inode *(*get_inode)
1378 (struct super_block *sb, u64 ino, u32 gen))
1380 struct inode *inode = NULL;
1386 case FILEID_INO32_GEN:
1387 case FILEID_INO32_GEN_PARENT:
1388 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
1392 return d_obtain_alias(inode);
1394 EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
1397 * generic_fh_to_parent - generic helper for the fh_to_parent export operation
1398 * @sb: filesystem to do the file handle conversion on
1399 * @fid: file handle to convert
1400 * @fh_len: length of the file handle in bytes
1401 * @fh_type: type of file handle
1402 * @get_inode: filesystem callback to retrieve inode
1404 * This function decodes @fid as long as it has one of the well-known
1405 * Linux filehandle types and calls @get_inode on it to retrieve the
1406 * inode for the _parent_ object specified in the file handle if it
1407 * is specified in the file handle, or NULL otherwise.
1409 struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
1410 int fh_len, int fh_type, struct inode *(*get_inode)
1411 (struct super_block *sb, u64 ino, u32 gen))
1413 struct inode *inode = NULL;
1419 case FILEID_INO32_GEN_PARENT:
1420 inode = get_inode(sb, fid->i32.parent_ino,
1421 (fh_len > 3 ? fid->i32.parent_gen : 0));
1425 return d_obtain_alias(inode);
1427 EXPORT_SYMBOL_GPL(generic_fh_to_parent);
1430 * __generic_file_fsync - generic fsync implementation for simple filesystems
1432 * @file: file to synchronize
1433 * @start: start offset in bytes
1434 * @end: end offset in bytes (inclusive)
1435 * @datasync: only synchronize essential metadata if true
1437 * This is a generic implementation of the fsync method for simple
1438 * filesystems which track all non-inode metadata in the buffers list
1439 * hanging off the address_space structure.
1441 int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
1444 struct inode *inode = file->f_mapping->host;
1448 err = file_write_and_wait_range(file, start, end);
1453 ret = sync_mapping_buffers(inode->i_mapping);
1454 if (!(inode->i_state & I_DIRTY_ALL))
1456 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
1459 err = sync_inode_metadata(inode, 1);
1464 inode_unlock(inode);
1465 /* check and advance again to catch errors after syncing out buffers */
1466 err = file_check_and_advance_wb_err(file);
1471 EXPORT_SYMBOL(__generic_file_fsync);
1474 * generic_file_fsync - generic fsync implementation for simple filesystems
1476 * @file: file to synchronize
1477 * @start: start offset in bytes
1478 * @end: end offset in bytes (inclusive)
1479 * @datasync: only synchronize essential metadata if true
1483 int generic_file_fsync(struct file *file, loff_t start, loff_t end,
1486 struct inode *inode = file->f_mapping->host;
1489 err = __generic_file_fsync(file, start, end, datasync);
1492 return blkdev_issue_flush(inode->i_sb->s_bdev);
1494 EXPORT_SYMBOL(generic_file_fsync);
1497 * generic_check_addressable - Check addressability of file system
1498 * @blocksize_bits: log of file system block size
1499 * @num_blocks: number of blocks in file system
1501 * Determine whether a file system with @num_blocks blocks (and a
1502 * block size of 2**@blocksize_bits) is addressable by the sector_t
1503 * and page cache of the system. Return 0 if so and -EFBIG otherwise.
1505 int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
1507 u64 last_fs_block = num_blocks - 1;
1509 last_fs_block >> (PAGE_SHIFT - blocksize_bits);
1511 if (unlikely(num_blocks == 0))
1514 if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
1517 if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
1518 (last_fs_page > (pgoff_t)(~0ULL))) {
1523 EXPORT_SYMBOL(generic_check_addressable);
1526 * No-op implementation of ->fsync for in-memory filesystems.
1528 int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
1532 EXPORT_SYMBOL(noop_fsync);
1534 ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
1537 * iomap based filesystems support direct I/O without need for
1538 * this callback. However, it still needs to be set in
1539 * inode->a_ops so that open/fcntl know that direct I/O is
1540 * generally supported.
1544 EXPORT_SYMBOL_GPL(noop_direct_IO);
1546 /* Because kfree isn't assignment-compatible with void(void*) ;-/ */
1547 void kfree_link(void *p)
1551 EXPORT_SYMBOL(kfree_link);
1553 struct inode *alloc_anon_inode(struct super_block *s)
1555 static const struct address_space_operations anon_aops = {
1556 .dirty_folio = noop_dirty_folio,
1558 struct inode *inode = new_inode_pseudo(s);
1561 return ERR_PTR(-ENOMEM);
1563 inode->i_ino = get_next_ino();
1564 inode->i_mapping->a_ops = &anon_aops;
1567 * Mark the inode dirty from the very beginning,
1568 * that way it will never be moved to the dirty
1569 * list because mark_inode_dirty() will think
1570 * that it already _is_ on the dirty list.
1572 inode->i_state = I_DIRTY;
1573 inode->i_mode = S_IRUSR | S_IWUSR;
1574 inode->i_uid = current_fsuid();
1575 inode->i_gid = current_fsgid();
1576 inode->i_flags |= S_PRIVATE;
1577 simple_inode_init_ts(inode);
1580 EXPORT_SYMBOL(alloc_anon_inode);
1583 * simple_nosetlease - generic helper for prohibiting leases
1584 * @filp: file pointer
1585 * @arg: type of lease to obtain
1586 * @flp: new lease supplied for insertion
1587 * @priv: private data for lm_setup operation
1589 * Generic helper for filesystems that do not wish to allow leases to be set.
1590 * All arguments are ignored and it just returns -EINVAL.
1593 simple_nosetlease(struct file *filp, int arg, struct file_lock **flp,
1598 EXPORT_SYMBOL(simple_nosetlease);
1601 * simple_get_link - generic helper to get the target of "fast" symlinks
1602 * @dentry: not used here
1603 * @inode: the symlink inode
1604 * @done: not used here
1606 * Generic helper for filesystems to use for symlink inodes where a pointer to
1607 * the symlink target is stored in ->i_link. NOTE: this isn't normally called,
1608 * since as an optimization the path lookup code uses any non-NULL ->i_link
1609 * directly, without calling ->get_link(). But ->get_link() still must be set,
1610 * to mark the inode_operations as being for a symlink.
1612 * Return: the symlink target
1614 const char *simple_get_link(struct dentry *dentry, struct inode *inode,
1615 struct delayed_call *done)
1617 return inode->i_link;
1619 EXPORT_SYMBOL(simple_get_link);
1621 const struct inode_operations simple_symlink_inode_operations = {
1622 .get_link = simple_get_link,
1624 EXPORT_SYMBOL(simple_symlink_inode_operations);
1627 * Operations for a permanently empty directory.
1629 static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
1631 return ERR_PTR(-ENOENT);
1634 static int empty_dir_getattr(struct mnt_idmap *idmap,
1635 const struct path *path, struct kstat *stat,
1636 u32 request_mask, unsigned int query_flags)
1638 struct inode *inode = d_inode(path->dentry);
1639 generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
1643 static int empty_dir_setattr(struct mnt_idmap *idmap,
1644 struct dentry *dentry, struct iattr *attr)
1649 static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size)
1654 static const struct inode_operations empty_dir_inode_operations = {
1655 .lookup = empty_dir_lookup,
1656 .permission = generic_permission,
1657 .setattr = empty_dir_setattr,
1658 .getattr = empty_dir_getattr,
1659 .listxattr = empty_dir_listxattr,
1662 static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence)
1664 /* An empty directory has two entries . and .. at offsets 0 and 1 */
1665 return generic_file_llseek_size(file, offset, whence, 2, 2);
1668 static int empty_dir_readdir(struct file *file, struct dir_context *ctx)
1670 dir_emit_dots(file, ctx);
1674 static const struct file_operations empty_dir_operations = {
1675 .llseek = empty_dir_llseek,
1676 .read = generic_read_dir,
1677 .iterate_shared = empty_dir_readdir,
1678 .fsync = noop_fsync,
1682 void make_empty_dir_inode(struct inode *inode)
1684 set_nlink(inode, 2);
1685 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
1686 inode->i_uid = GLOBAL_ROOT_UID;
1687 inode->i_gid = GLOBAL_ROOT_GID;
1690 inode->i_blkbits = PAGE_SHIFT;
1691 inode->i_blocks = 0;
1693 inode->i_op = &empty_dir_inode_operations;
1694 inode->i_opflags &= ~IOP_XATTR;
1695 inode->i_fop = &empty_dir_operations;
1698 bool is_empty_dir_inode(struct inode *inode)
1700 return (inode->i_fop == &empty_dir_operations) &&
1701 (inode->i_op == &empty_dir_inode_operations);
1704 #if IS_ENABLED(CONFIG_UNICODE)
1706 * generic_ci_d_compare - generic d_compare implementation for casefolding filesystems
1707 * @dentry: dentry whose name we are checking against
1708 * @len: len of name of dentry
1709 * @str: str pointer to name of dentry
1710 * @name: Name to compare against
1712 * Return: 0 if names match, 1 if mismatch, or -ERRNO
1714 static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
1715 const char *str, const struct qstr *name)
1717 const struct dentry *parent = READ_ONCE(dentry->d_parent);
1718 const struct inode *dir = READ_ONCE(parent->d_inode);
1719 const struct super_block *sb = dentry->d_sb;
1720 const struct unicode_map *um = sb->s_encoding;
1721 struct qstr qstr = QSTR_INIT(str, len);
1722 char strbuf[DNAME_INLINE_LEN];
1725 if (!dir || !IS_CASEFOLDED(dir))
1728 * If the dentry name is stored in-line, then it may be concurrently
1729 * modified by a rename. If this happens, the VFS will eventually retry
1730 * the lookup, so it doesn't matter what ->d_compare() returns.
1731 * However, it's unsafe to call utf8_strncasecmp() with an unstable
1732 * string. Therefore, we have to copy the name into a temporary buffer.
1734 if (len <= DNAME_INLINE_LEN - 1) {
1735 memcpy(strbuf, str, len);
1738 /* prevent compiler from optimizing out the temporary buffer */
1741 ret = utf8_strncasecmp(um, name, &qstr);
1745 if (sb_has_strict_encoding(sb))
1748 if (len != name->len)
1750 return !!memcmp(str, name->name, len);
1754 * generic_ci_d_hash - generic d_hash implementation for casefolding filesystems
1755 * @dentry: dentry of the parent directory
1756 * @str: qstr of name whose hash we should fill in
1758 * Return: 0 if hash was successful or unchanged, and -EINVAL on error
1760 static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
1762 const struct inode *dir = READ_ONCE(dentry->d_inode);
1763 struct super_block *sb = dentry->d_sb;
1764 const struct unicode_map *um = sb->s_encoding;
1767 if (!dir || !IS_CASEFOLDED(dir))
1770 ret = utf8_casefold_hash(um, dentry, str);
1771 if (ret < 0 && sb_has_strict_encoding(sb))
1776 static const struct dentry_operations generic_ci_dentry_ops = {
1777 .d_hash = generic_ci_d_hash,
1778 .d_compare = generic_ci_d_compare,
1782 #ifdef CONFIG_FS_ENCRYPTION
1783 static const struct dentry_operations generic_encrypted_dentry_ops = {
1784 .d_revalidate = fscrypt_d_revalidate,
1788 #if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE)
1789 static const struct dentry_operations generic_encrypted_ci_dentry_ops = {
1790 .d_hash = generic_ci_d_hash,
1791 .d_compare = generic_ci_d_compare,
1792 .d_revalidate = fscrypt_d_revalidate,
1797 * generic_set_encrypted_ci_d_ops - helper for setting d_ops for given dentry
1798 * @dentry: dentry to set ops on
1800 * Casefolded directories need d_hash and d_compare set, so that the dentries
1801 * contained in them are handled case-insensitively. Note that these operations
1802 * are needed on the parent directory rather than on the dentries in it, and
1803 * while the casefolding flag can be toggled on and off on an empty directory,
1804 * dentry_operations can't be changed later. As a result, if the filesystem has
1805 * casefolding support enabled at all, we have to give all dentries the
1806 * casefolding operations even if their inode doesn't have the casefolding flag
1807 * currently (and thus the casefolding ops would be no-ops for now).
1809 * Encryption works differently in that the only dentry operation it needs is
1810 * d_revalidate, which it only needs on dentries that have the no-key name flag.
1811 * The no-key flag can't be set "later", so we don't have to worry about that.
1813 * Finally, to maximize compatibility with overlayfs (which isn't compatible
1814 * with certain dentry operations) and to avoid taking an unnecessary
1815 * performance hit, we use custom dentry_operations for each possible
1816 * combination rather than always installing all operations.
1818 void generic_set_encrypted_ci_d_ops(struct dentry *dentry)
1820 #ifdef CONFIG_FS_ENCRYPTION
1821 bool needs_encrypt_ops = dentry->d_flags & DCACHE_NOKEY_NAME;
1823 #if IS_ENABLED(CONFIG_UNICODE)
1824 bool needs_ci_ops = dentry->d_sb->s_encoding;
1826 #if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE)
1827 if (needs_encrypt_ops && needs_ci_ops) {
1828 d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops);
1832 #ifdef CONFIG_FS_ENCRYPTION
1833 if (needs_encrypt_ops) {
1834 d_set_d_op(dentry, &generic_encrypted_dentry_ops);
1838 #if IS_ENABLED(CONFIG_UNICODE)
1840 d_set_d_op(dentry, &generic_ci_dentry_ops);
1845 EXPORT_SYMBOL(generic_set_encrypted_ci_d_ops);
1848 * inode_maybe_inc_iversion - increments i_version
1849 * @inode: inode with the i_version that should be updated
1850 * @force: increment the counter even if it's not necessary?
1852 * Every time the inode is modified, the i_version field must be seen to have
1853 * changed by any observer.
1855 * If "force" is set or the QUERIED flag is set, then ensure that we increment
1856 * the value, and clear the queried flag.
1858 * In the common case where neither is set, then we can return "false" without
1859 * updating i_version.
1861 * If this function returns false, and no other metadata has changed, then we
1862 * can avoid logging the metadata.
1864 bool inode_maybe_inc_iversion(struct inode *inode, bool force)
1869 * The i_version field is not strictly ordered with any other inode
1870 * information, but the legacy inode_inc_iversion code used a spinlock
1871 * to serialize increments.
1873 * Here, we add full memory barriers to ensure that any de-facto
1874 * ordering with other info is preserved.
1876 * This barrier pairs with the barrier in inode_query_iversion()
1879 cur = inode_peek_iversion_raw(inode);
1881 /* If flag is clear then we needn't do anything */
1882 if (!force && !(cur & I_VERSION_QUERIED))
1885 /* Since lowest bit is flag, add 2 to avoid it */
1886 new = (cur & ~I_VERSION_QUERIED) + I_VERSION_INCREMENT;
1887 } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new));
1890 EXPORT_SYMBOL(inode_maybe_inc_iversion);
1893 * inode_query_iversion - read i_version for later use
1894 * @inode: inode from which i_version should be read
1896 * Read the inode i_version counter. This should be used by callers that wish
1897 * to store the returned i_version for later comparison. This will guarantee
1898 * that a later query of the i_version will result in a different value if
1899 * anything has changed.
1901 * In this implementation, we fetch the current value, set the QUERIED flag and
1902 * then try to swap it into place with a cmpxchg, if it wasn't already set. If
1903 * that fails, we try again with the newly fetched value from the cmpxchg.
1905 u64 inode_query_iversion(struct inode *inode)
1909 cur = inode_peek_iversion_raw(inode);
1911 /* If flag is already set, then no need to swap */
1912 if (cur & I_VERSION_QUERIED) {
1914 * This barrier (and the implicit barrier in the
1915 * cmpxchg below) pairs with the barrier in
1916 * inode_maybe_inc_iversion().
1922 new = cur | I_VERSION_QUERIED;
1923 } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new));
1924 return cur >> I_VERSION_QUERIED_SHIFT;
1926 EXPORT_SYMBOL(inode_query_iversion);
1928 ssize_t direct_write_fallback(struct kiocb *iocb, struct iov_iter *iter,
1929 ssize_t direct_written, ssize_t buffered_written)
1931 struct address_space *mapping = iocb->ki_filp->f_mapping;
1932 loff_t pos = iocb->ki_pos - buffered_written;
1933 loff_t end = iocb->ki_pos - 1;
1937 * If the buffered write fallback returned an error, we want to return
1938 * the number of bytes which were written by direct I/O, or the error
1939 * code if that was zero.
1941 * Note that this differs from normal direct-io semantics, which will
1942 * return -EFOO even if some bytes were written.
1944 if (unlikely(buffered_written < 0)) {
1946 return direct_written;
1947 return buffered_written;
1951 * We need to ensure that the page cache pages are written to disk and
1952 * invalidated to preserve the expected O_DIRECT semantics.
1954 err = filemap_write_and_wait_range(mapping, pos, end);
1957 * We don't know how much we wrote, so just return the number of
1958 * bytes which were direct-written
1960 iocb->ki_pos -= buffered_written;
1962 return direct_written;
1965 invalidate_mapping_pages(mapping, pos >> PAGE_SHIFT, end >> PAGE_SHIFT);
1966 return direct_written + buffered_written;
1968 EXPORT_SYMBOL_GPL(direct_write_fallback);
1971 * simple_inode_init_ts - initialize the timestamps for a new inode
1972 * @inode: inode to be initialized
1974 * When a new inode is created, most filesystems set the timestamps to the
1975 * current time. Add a helper to do this.
1977 struct timespec64 simple_inode_init_ts(struct inode *inode)
1979 struct timespec64 ts = inode_set_ctime_current(inode);
1981 inode_set_atime_to_ts(inode, ts);
1982 inode_set_mtime_to_ts(inode, ts);
1985 EXPORT_SYMBOL(simple_inode_init_ts);