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9d9539db86
As Linus suggested this enables pidfs unconditionally. A key property to retain is the ability to compare pidfds by inode number (cf. [1]). That's extremely helpful just as comparing namespace file descriptors by inode number is. They are used in a variety of scenarios where they need to be compared, e.g., when receiving a pidfd via SO_PEERPIDFD from a socket to trivially authenticate a the sender and various other use-cases. For 64bit systems this is pretty trivial to do. For 32bit it's slightly more annoying as we discussed but we simply add a dumb ida based allocator that gets used on 32bit. This gives the same guarantees about inode numbers on 64bit without any overflow risk. Practically, we'll never run into overflow issues because we're constrained by the number of processes that can exist on 32bit and by the number of open files that can exist on a 32bit system. On 64bit none of this matters and things are very simple. If 32bit also needs the uniqueness guarantee they can simply parse the contents of /proc/<pid>/fd/<nr>. The uniqueness guarantees have a variety of use-cases. One of the most obvious ones is that they will make pidfiles (or "pidfdfiles", I guess) reliable as the unique identifier can be placed into there that won't be reycled. Also a frequent request. Note, I took the chance and simplified path_from_stashed() even further. Instead of passing the inode number explicitly to path_from_stashed() we let the filesystem handle that internally. So path_from_stashed() ends up even simpler than it is now. This is also a good solution allowing the cleanup code to be clean and consistent between 32bit and 64bit. The cleanup path in prepare_anon_dentry() is also switched around so we put the inode before the dentry allocation. This means we only have to call the cleanup handler for the filesystem's inode data once and can rely ->evict_inode() otherwise. Aside from having to have a bit of extra code for 32bit it actually ends up a nice cleanup for path_from_stashed() imho. Tested on both 32 and 64bit including error injection. Link: https://github.com/systemd/systemd/pull/31713 [1] Link: https://lore.kernel.org/r/20240312-dingo-sehnlich-b3ecc35c6de7@brauner Signed-off-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2133 lines
56 KiB
C
2133 lines
56 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* fs/libfs.c
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* Library for filesystems writers.
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*/
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#include <linux/blkdev.h>
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#include <linux/export.h>
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#include <linux/pagemap.h>
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#include <linux/slab.h>
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#include <linux/cred.h>
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#include <linux/mount.h>
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#include <linux/vfs.h>
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#include <linux/quotaops.h>
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#include <linux/mutex.h>
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#include <linux/namei.h>
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#include <linux/exportfs.h>
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#include <linux/iversion.h>
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#include <linux/writeback.h>
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#include <linux/buffer_head.h> /* sync_mapping_buffers */
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#include <linux/fs_context.h>
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#include <linux/pseudo_fs.h>
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#include <linux/fsnotify.h>
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#include <linux/unicode.h>
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#include <linux/fscrypt.h>
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#include <linux/pidfs.h>
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#include <linux/uaccess.h>
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#include "internal.h"
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int simple_getattr(struct mnt_idmap *idmap, const struct path *path,
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struct kstat *stat, u32 request_mask,
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unsigned int query_flags)
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{
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struct inode *inode = d_inode(path->dentry);
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generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
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stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
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return 0;
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}
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EXPORT_SYMBOL(simple_getattr);
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int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
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{
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u64 id = huge_encode_dev(dentry->d_sb->s_dev);
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buf->f_fsid = u64_to_fsid(id);
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buf->f_type = dentry->d_sb->s_magic;
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buf->f_bsize = PAGE_SIZE;
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buf->f_namelen = NAME_MAX;
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return 0;
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}
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EXPORT_SYMBOL(simple_statfs);
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/*
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* Retaining negative dentries for an in-memory filesystem just wastes
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* memory and lookup time: arrange for them to be deleted immediately.
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*/
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int always_delete_dentry(const struct dentry *dentry)
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{
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return 1;
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}
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EXPORT_SYMBOL(always_delete_dentry);
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const struct dentry_operations simple_dentry_operations = {
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.d_delete = always_delete_dentry,
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};
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EXPORT_SYMBOL(simple_dentry_operations);
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/*
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* Lookup the data. This is trivial - if the dentry didn't already
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* exist, we know it is negative. Set d_op to delete negative dentries.
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*/
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struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
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{
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if (dentry->d_name.len > NAME_MAX)
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return ERR_PTR(-ENAMETOOLONG);
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if (!dentry->d_sb->s_d_op)
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d_set_d_op(dentry, &simple_dentry_operations);
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d_add(dentry, NULL);
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return NULL;
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}
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EXPORT_SYMBOL(simple_lookup);
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int dcache_dir_open(struct inode *inode, struct file *file)
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{
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file->private_data = d_alloc_cursor(file->f_path.dentry);
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return file->private_data ? 0 : -ENOMEM;
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}
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EXPORT_SYMBOL(dcache_dir_open);
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int dcache_dir_close(struct inode *inode, struct file *file)
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{
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dput(file->private_data);
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return 0;
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}
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EXPORT_SYMBOL(dcache_dir_close);
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/* parent is locked at least shared */
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/*
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* Returns an element of siblings' list.
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* We are looking for <count>th positive after <p>; if
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* found, dentry is grabbed and returned to caller.
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* If no such element exists, NULL is returned.
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*/
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static struct dentry *scan_positives(struct dentry *cursor,
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struct hlist_node **p,
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loff_t count,
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struct dentry *last)
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{
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struct dentry *dentry = cursor->d_parent, *found = NULL;
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spin_lock(&dentry->d_lock);
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while (*p) {
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struct dentry *d = hlist_entry(*p, struct dentry, d_sib);
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p = &d->d_sib.next;
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// we must at least skip cursors, to avoid livelocks
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if (d->d_flags & DCACHE_DENTRY_CURSOR)
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continue;
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if (simple_positive(d) && !--count) {
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spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
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if (simple_positive(d))
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found = dget_dlock(d);
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spin_unlock(&d->d_lock);
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if (likely(found))
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break;
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count = 1;
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}
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if (need_resched()) {
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if (!hlist_unhashed(&cursor->d_sib))
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__hlist_del(&cursor->d_sib);
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hlist_add_behind(&cursor->d_sib, &d->d_sib);
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p = &cursor->d_sib.next;
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spin_unlock(&dentry->d_lock);
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cond_resched();
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spin_lock(&dentry->d_lock);
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}
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}
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spin_unlock(&dentry->d_lock);
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dput(last);
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return found;
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}
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loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
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{
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struct dentry *dentry = file->f_path.dentry;
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switch (whence) {
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case 1:
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offset += file->f_pos;
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fallthrough;
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case 0:
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if (offset >= 0)
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break;
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fallthrough;
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default:
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return -EINVAL;
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}
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if (offset != file->f_pos) {
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struct dentry *cursor = file->private_data;
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struct dentry *to = NULL;
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inode_lock_shared(dentry->d_inode);
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if (offset > 2)
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to = scan_positives(cursor, &dentry->d_children.first,
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offset - 2, NULL);
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spin_lock(&dentry->d_lock);
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hlist_del_init(&cursor->d_sib);
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if (to)
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hlist_add_behind(&cursor->d_sib, &to->d_sib);
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spin_unlock(&dentry->d_lock);
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dput(to);
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file->f_pos = offset;
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inode_unlock_shared(dentry->d_inode);
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}
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return offset;
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}
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EXPORT_SYMBOL(dcache_dir_lseek);
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/*
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* Directory is locked and all positive dentries in it are safe, since
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* for ramfs-type trees they can't go away without unlink() or rmdir(),
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* both impossible due to the lock on directory.
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*/
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int dcache_readdir(struct file *file, struct dir_context *ctx)
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{
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struct dentry *dentry = file->f_path.dentry;
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struct dentry *cursor = file->private_data;
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struct dentry *next = NULL;
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struct hlist_node **p;
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if (!dir_emit_dots(file, ctx))
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return 0;
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if (ctx->pos == 2)
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p = &dentry->d_children.first;
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else
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p = &cursor->d_sib.next;
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while ((next = scan_positives(cursor, p, 1, next)) != NULL) {
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if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
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d_inode(next)->i_ino,
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fs_umode_to_dtype(d_inode(next)->i_mode)))
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break;
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ctx->pos++;
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p = &next->d_sib.next;
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}
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spin_lock(&dentry->d_lock);
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hlist_del_init(&cursor->d_sib);
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if (next)
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hlist_add_before(&cursor->d_sib, &next->d_sib);
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spin_unlock(&dentry->d_lock);
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dput(next);
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return 0;
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}
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EXPORT_SYMBOL(dcache_readdir);
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ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
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{
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return -EISDIR;
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}
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EXPORT_SYMBOL(generic_read_dir);
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const struct file_operations simple_dir_operations = {
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.open = dcache_dir_open,
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.release = dcache_dir_close,
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.llseek = dcache_dir_lseek,
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.read = generic_read_dir,
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.iterate_shared = dcache_readdir,
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.fsync = noop_fsync,
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};
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EXPORT_SYMBOL(simple_dir_operations);
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const struct inode_operations simple_dir_inode_operations = {
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.lookup = simple_lookup,
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};
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EXPORT_SYMBOL(simple_dir_inode_operations);
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/* 0 is '.', 1 is '..', so always start with offset 2 or more */
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enum {
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DIR_OFFSET_MIN = 2,
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};
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static void offset_set(struct dentry *dentry, long offset)
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{
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dentry->d_fsdata = (void *)offset;
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}
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static long dentry2offset(struct dentry *dentry)
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{
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return (long)dentry->d_fsdata;
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}
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static struct lock_class_key simple_offset_lock_class;
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/**
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* simple_offset_init - initialize an offset_ctx
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* @octx: directory offset map to be initialized
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*
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*/
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void simple_offset_init(struct offset_ctx *octx)
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{
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mt_init_flags(&octx->mt, MT_FLAGS_ALLOC_RANGE);
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lockdep_set_class(&octx->mt.ma_lock, &simple_offset_lock_class);
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octx->next_offset = DIR_OFFSET_MIN;
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}
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/**
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* simple_offset_add - Add an entry to a directory's offset map
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* @octx: directory offset ctx to be updated
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* @dentry: new dentry being added
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*
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* Returns zero on success. @octx and the dentry's offset are updated.
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* Otherwise, a negative errno value is returned.
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*/
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int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry)
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{
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unsigned long offset;
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int ret;
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if (dentry2offset(dentry) != 0)
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return -EBUSY;
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ret = mtree_alloc_cyclic(&octx->mt, &offset, dentry, DIR_OFFSET_MIN,
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LONG_MAX, &octx->next_offset, GFP_KERNEL);
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if (ret < 0)
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return ret;
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offset_set(dentry, offset);
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return 0;
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}
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/**
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* simple_offset_remove - Remove an entry to a directory's offset map
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* @octx: directory offset ctx to be updated
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* @dentry: dentry being removed
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*
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*/
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void simple_offset_remove(struct offset_ctx *octx, struct dentry *dentry)
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{
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long offset;
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offset = dentry2offset(dentry);
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if (offset == 0)
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return;
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mtree_erase(&octx->mt, offset);
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offset_set(dentry, 0);
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}
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/**
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* simple_offset_empty - Check if a dentry can be unlinked
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* @dentry: dentry to be tested
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*
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* Returns 0 if @dentry is a non-empty directory; otherwise returns 1.
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*/
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int simple_offset_empty(struct dentry *dentry)
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{
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struct inode *inode = d_inode(dentry);
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struct offset_ctx *octx;
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struct dentry *child;
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unsigned long index;
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int ret = 1;
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if (!inode || !S_ISDIR(inode->i_mode))
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return ret;
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index = DIR_OFFSET_MIN;
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octx = inode->i_op->get_offset_ctx(inode);
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mt_for_each(&octx->mt, child, index, LONG_MAX) {
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spin_lock(&child->d_lock);
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if (simple_positive(child)) {
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spin_unlock(&child->d_lock);
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ret = 0;
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break;
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}
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spin_unlock(&child->d_lock);
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}
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return ret;
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}
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/**
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* simple_offset_rename_exchange - exchange rename with directory offsets
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* @old_dir: parent of dentry being moved
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* @old_dentry: dentry being moved
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* @new_dir: destination parent
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* @new_dentry: destination dentry
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*
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* Returns zero on success. Otherwise a negative errno is returned and the
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* rename is rolled back.
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*/
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int simple_offset_rename_exchange(struct inode *old_dir,
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struct dentry *old_dentry,
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struct inode *new_dir,
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struct dentry *new_dentry)
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{
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struct offset_ctx *old_ctx = old_dir->i_op->get_offset_ctx(old_dir);
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struct offset_ctx *new_ctx = new_dir->i_op->get_offset_ctx(new_dir);
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long old_index = dentry2offset(old_dentry);
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long new_index = dentry2offset(new_dentry);
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int ret;
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simple_offset_remove(old_ctx, old_dentry);
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simple_offset_remove(new_ctx, new_dentry);
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ret = simple_offset_add(new_ctx, old_dentry);
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if (ret)
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goto out_restore;
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ret = simple_offset_add(old_ctx, new_dentry);
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if (ret) {
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simple_offset_remove(new_ctx, old_dentry);
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goto out_restore;
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}
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ret = simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry);
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if (ret) {
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simple_offset_remove(new_ctx, old_dentry);
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simple_offset_remove(old_ctx, new_dentry);
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goto out_restore;
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}
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return 0;
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out_restore:
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offset_set(old_dentry, old_index);
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mtree_store(&old_ctx->mt, old_index, old_dentry, GFP_KERNEL);
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offset_set(new_dentry, new_index);
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mtree_store(&new_ctx->mt, new_index, new_dentry, GFP_KERNEL);
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return ret;
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}
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/**
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* simple_offset_destroy - Release offset map
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* @octx: directory offset ctx that is about to be destroyed
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*
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* During fs teardown (eg. umount), a directory's offset map might still
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* contain entries. xa_destroy() cleans out anything that remains.
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*/
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void simple_offset_destroy(struct offset_ctx *octx)
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{
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mtree_destroy(&octx->mt);
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}
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/**
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* offset_dir_llseek - Advance the read position of a directory descriptor
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* @file: an open directory whose position is to be updated
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* @offset: a byte offset
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* @whence: enumerator describing the starting position for this update
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*
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* SEEK_END, SEEK_DATA, and SEEK_HOLE are not supported for directories.
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*
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* Returns the updated read position if successful; otherwise a
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* negative errno is returned and the read position remains unchanged.
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*/
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static loff_t offset_dir_llseek(struct file *file, loff_t offset, int whence)
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{
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switch (whence) {
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case SEEK_CUR:
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offset += file->f_pos;
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fallthrough;
|
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case SEEK_SET:
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if (offset >= 0)
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break;
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fallthrough;
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default:
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return -EINVAL;
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}
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|
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/* In this case, ->private_data is protected by f_pos_lock */
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file->private_data = NULL;
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return vfs_setpos(file, offset, LONG_MAX);
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}
|
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|
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static struct dentry *offset_find_next(struct offset_ctx *octx, loff_t offset)
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{
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MA_STATE(mas, &octx->mt, offset, offset);
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struct dentry *child, *found = NULL;
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rcu_read_lock();
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child = mas_find(&mas, LONG_MAX);
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if (!child)
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goto out;
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spin_lock(&child->d_lock);
|
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if (simple_positive(child))
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found = dget_dlock(child);
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spin_unlock(&child->d_lock);
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out:
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rcu_read_unlock();
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return found;
|
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}
|
|
|
|
static bool offset_dir_emit(struct dir_context *ctx, struct dentry *dentry)
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|
{
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|
struct inode *inode = d_inode(dentry);
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|
long offset = dentry2offset(dentry);
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|
|
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return ctx->actor(ctx, dentry->d_name.name, dentry->d_name.len, offset,
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|
inode->i_ino, fs_umode_to_dtype(inode->i_mode));
|
|
}
|
|
|
|
static void *offset_iterate_dir(struct inode *inode, struct dir_context *ctx)
|
|
{
|
|
struct offset_ctx *octx = inode->i_op->get_offset_ctx(inode);
|
|
struct dentry *dentry;
|
|
|
|
while (true) {
|
|
dentry = offset_find_next(octx, ctx->pos);
|
|
if (!dentry)
|
|
return ERR_PTR(-ENOENT);
|
|
|
|
if (!offset_dir_emit(ctx, dentry)) {
|
|
dput(dentry);
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break;
|
|
}
|
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|
|
ctx->pos = dentry2offset(dentry) + 1;
|
|
dput(dentry);
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* offset_readdir - Emit entries starting at offset @ctx->pos
|
|
* @file: an open directory to iterate over
|
|
* @ctx: directory iteration context
|
|
*
|
|
* Caller must hold @file's i_rwsem to prevent insertion or removal of
|
|
* entries during this call.
|
|
*
|
|
* On entry, @ctx->pos contains an offset that represents the first entry
|
|
* to be read from the directory.
|
|
*
|
|
* The operation continues until there are no more entries to read, or
|
|
* until the ctx->actor indicates there is no more space in the caller's
|
|
* output buffer.
|
|
*
|
|
* On return, @ctx->pos contains an offset that will read the next entry
|
|
* in this directory when offset_readdir() is called again with @ctx.
|
|
*
|
|
* Return values:
|
|
* %0 - Complete
|
|
*/
|
|
static int offset_readdir(struct file *file, struct dir_context *ctx)
|
|
{
|
|
struct dentry *dir = file->f_path.dentry;
|
|
|
|
lockdep_assert_held(&d_inode(dir)->i_rwsem);
|
|
|
|
if (!dir_emit_dots(file, ctx))
|
|
return 0;
|
|
|
|
/* In this case, ->private_data is protected by f_pos_lock */
|
|
if (ctx->pos == DIR_OFFSET_MIN)
|
|
file->private_data = NULL;
|
|
else if (file->private_data == ERR_PTR(-ENOENT))
|
|
return 0;
|
|
file->private_data = offset_iterate_dir(d_inode(dir), ctx);
|
|
return 0;
|
|
}
|
|
|
|
const struct file_operations simple_offset_dir_operations = {
|
|
.llseek = offset_dir_llseek,
|
|
.iterate_shared = offset_readdir,
|
|
.read = generic_read_dir,
|
|
.fsync = noop_fsync,
|
|
};
|
|
|
|
static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev)
|
|
{
|
|
struct dentry *child = NULL, *d;
|
|
|
|
spin_lock(&parent->d_lock);
|
|
d = prev ? d_next_sibling(prev) : d_first_child(parent);
|
|
hlist_for_each_entry_from(d, d_sib) {
|
|
if (simple_positive(d)) {
|
|
spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
|
|
if (simple_positive(d))
|
|
child = dget_dlock(d);
|
|
spin_unlock(&d->d_lock);
|
|
if (likely(child))
|
|
break;
|
|
}
|
|
}
|
|
spin_unlock(&parent->d_lock);
|
|
dput(prev);
|
|
return child;
|
|
}
|
|
|
|
void simple_recursive_removal(struct dentry *dentry,
|
|
void (*callback)(struct dentry *))
|
|
{
|
|
struct dentry *this = dget(dentry);
|
|
while (true) {
|
|
struct dentry *victim = NULL, *child;
|
|
struct inode *inode = this->d_inode;
|
|
|
|
inode_lock(inode);
|
|
if (d_is_dir(this))
|
|
inode->i_flags |= S_DEAD;
|
|
while ((child = find_next_child(this, victim)) == NULL) {
|
|
// kill and ascend
|
|
// update metadata while it's still locked
|
|
inode_set_ctime_current(inode);
|
|
clear_nlink(inode);
|
|
inode_unlock(inode);
|
|
victim = this;
|
|
this = this->d_parent;
|
|
inode = this->d_inode;
|
|
inode_lock(inode);
|
|
if (simple_positive(victim)) {
|
|
d_invalidate(victim); // avoid lost mounts
|
|
if (d_is_dir(victim))
|
|
fsnotify_rmdir(inode, victim);
|
|
else
|
|
fsnotify_unlink(inode, victim);
|
|
if (callback)
|
|
callback(victim);
|
|
dput(victim); // unpin it
|
|
}
|
|
if (victim == dentry) {
|
|
inode_set_mtime_to_ts(inode,
|
|
inode_set_ctime_current(inode));
|
|
if (d_is_dir(dentry))
|
|
drop_nlink(inode);
|
|
inode_unlock(inode);
|
|
dput(dentry);
|
|
return;
|
|
}
|
|
}
|
|
inode_unlock(inode);
|
|
this = child;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(simple_recursive_removal);
|
|
|
|
static const struct super_operations simple_super_operations = {
|
|
.statfs = simple_statfs,
|
|
};
|
|
|
|
static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc)
|
|
{
|
|
struct pseudo_fs_context *ctx = fc->fs_private;
|
|
struct inode *root;
|
|
|
|
s->s_maxbytes = MAX_LFS_FILESIZE;
|
|
s->s_blocksize = PAGE_SIZE;
|
|
s->s_blocksize_bits = PAGE_SHIFT;
|
|
s->s_magic = ctx->magic;
|
|
s->s_op = ctx->ops ?: &simple_super_operations;
|
|
s->s_xattr = ctx->xattr;
|
|
s->s_time_gran = 1;
|
|
root = new_inode(s);
|
|
if (!root)
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* since this is the first inode, make it number 1. New inodes created
|
|
* after this must take care not to collide with it (by passing
|
|
* max_reserved of 1 to iunique).
|
|
*/
|
|
root->i_ino = 1;
|
|
root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
|
|
simple_inode_init_ts(root);
|
|
s->s_root = d_make_root(root);
|
|
if (!s->s_root)
|
|
return -ENOMEM;
|
|
s->s_d_op = ctx->dops;
|
|
return 0;
|
|
}
|
|
|
|
static int pseudo_fs_get_tree(struct fs_context *fc)
|
|
{
|
|
return get_tree_nodev(fc, pseudo_fs_fill_super);
|
|
}
|
|
|
|
static void pseudo_fs_free(struct fs_context *fc)
|
|
{
|
|
kfree(fc->fs_private);
|
|
}
|
|
|
|
static const struct fs_context_operations pseudo_fs_context_ops = {
|
|
.free = pseudo_fs_free,
|
|
.get_tree = pseudo_fs_get_tree,
|
|
};
|
|
|
|
/*
|
|
* Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
|
|
* will never be mountable)
|
|
*/
|
|
struct pseudo_fs_context *init_pseudo(struct fs_context *fc,
|
|
unsigned long magic)
|
|
{
|
|
struct pseudo_fs_context *ctx;
|
|
|
|
ctx = kzalloc(sizeof(struct pseudo_fs_context), GFP_KERNEL);
|
|
if (likely(ctx)) {
|
|
ctx->magic = magic;
|
|
fc->fs_private = ctx;
|
|
fc->ops = &pseudo_fs_context_ops;
|
|
fc->sb_flags |= SB_NOUSER;
|
|
fc->global = true;
|
|
}
|
|
return ctx;
|
|
}
|
|
EXPORT_SYMBOL(init_pseudo);
|
|
|
|
int simple_open(struct inode *inode, struct file *file)
|
|
{
|
|
if (inode->i_private)
|
|
file->private_data = inode->i_private;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(simple_open);
|
|
|
|
int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
|
|
{
|
|
struct inode *inode = d_inode(old_dentry);
|
|
|
|
inode_set_mtime_to_ts(dir,
|
|
inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
|
|
inc_nlink(inode);
|
|
ihold(inode);
|
|
dget(dentry);
|
|
d_instantiate(dentry, inode);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(simple_link);
|
|
|
|
int simple_empty(struct dentry *dentry)
|
|
{
|
|
struct dentry *child;
|
|
int ret = 0;
|
|
|
|
spin_lock(&dentry->d_lock);
|
|
hlist_for_each_entry(child, &dentry->d_children, d_sib) {
|
|
spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
|
|
if (simple_positive(child)) {
|
|
spin_unlock(&child->d_lock);
|
|
goto out;
|
|
}
|
|
spin_unlock(&child->d_lock);
|
|
}
|
|
ret = 1;
|
|
out:
|
|
spin_unlock(&dentry->d_lock);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(simple_empty);
|
|
|
|
int simple_unlink(struct inode *dir, struct dentry *dentry)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
|
|
inode_set_mtime_to_ts(dir,
|
|
inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
|
|
drop_nlink(inode);
|
|
dput(dentry);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(simple_unlink);
|
|
|
|
int simple_rmdir(struct inode *dir, struct dentry *dentry)
|
|
{
|
|
if (!simple_empty(dentry))
|
|
return -ENOTEMPTY;
|
|
|
|
drop_nlink(d_inode(dentry));
|
|
simple_unlink(dir, dentry);
|
|
drop_nlink(dir);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(simple_rmdir);
|
|
|
|
/**
|
|
* simple_rename_timestamp - update the various inode timestamps for rename
|
|
* @old_dir: old parent directory
|
|
* @old_dentry: dentry that is being renamed
|
|
* @new_dir: new parent directory
|
|
* @new_dentry: target for rename
|
|
*
|
|
* POSIX mandates that the old and new parent directories have their ctime and
|
|
* mtime updated, and that inodes of @old_dentry and @new_dentry (if any), have
|
|
* their ctime updated.
|
|
*/
|
|
void simple_rename_timestamp(struct inode *old_dir, struct dentry *old_dentry,
|
|
struct inode *new_dir, struct dentry *new_dentry)
|
|
{
|
|
struct inode *newino = d_inode(new_dentry);
|
|
|
|
inode_set_mtime_to_ts(old_dir, inode_set_ctime_current(old_dir));
|
|
if (new_dir != old_dir)
|
|
inode_set_mtime_to_ts(new_dir,
|
|
inode_set_ctime_current(new_dir));
|
|
inode_set_ctime_current(d_inode(old_dentry));
|
|
if (newino)
|
|
inode_set_ctime_current(newino);
|
|
}
|
|
EXPORT_SYMBOL_GPL(simple_rename_timestamp);
|
|
|
|
int simple_rename_exchange(struct inode *old_dir, struct dentry *old_dentry,
|
|
struct inode *new_dir, struct dentry *new_dentry)
|
|
{
|
|
bool old_is_dir = d_is_dir(old_dentry);
|
|
bool new_is_dir = d_is_dir(new_dentry);
|
|
|
|
if (old_dir != new_dir && old_is_dir != new_is_dir) {
|
|
if (old_is_dir) {
|
|
drop_nlink(old_dir);
|
|
inc_nlink(new_dir);
|
|
} else {
|
|
drop_nlink(new_dir);
|
|
inc_nlink(old_dir);
|
|
}
|
|
}
|
|
simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(simple_rename_exchange);
|
|
|
|
int simple_rename(struct mnt_idmap *idmap, struct inode *old_dir,
|
|
struct dentry *old_dentry, struct inode *new_dir,
|
|
struct dentry *new_dentry, unsigned int flags)
|
|
{
|
|
int they_are_dirs = d_is_dir(old_dentry);
|
|
|
|
if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
|
|
return -EINVAL;
|
|
|
|
if (flags & RENAME_EXCHANGE)
|
|
return simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry);
|
|
|
|
if (!simple_empty(new_dentry))
|
|
return -ENOTEMPTY;
|
|
|
|
if (d_really_is_positive(new_dentry)) {
|
|
simple_unlink(new_dir, new_dentry);
|
|
if (they_are_dirs) {
|
|
drop_nlink(d_inode(new_dentry));
|
|
drop_nlink(old_dir);
|
|
}
|
|
} else if (they_are_dirs) {
|
|
drop_nlink(old_dir);
|
|
inc_nlink(new_dir);
|
|
}
|
|
|
|
simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(simple_rename);
|
|
|
|
/**
|
|
* simple_setattr - setattr for simple filesystem
|
|
* @idmap: idmap of the target mount
|
|
* @dentry: dentry
|
|
* @iattr: iattr structure
|
|
*
|
|
* Returns 0 on success, -error on failure.
|
|
*
|
|
* simple_setattr is a simple ->setattr implementation without a proper
|
|
* implementation of size changes.
|
|
*
|
|
* It can either be used for in-memory filesystems or special files
|
|
* on simple regular filesystems. Anything that needs to change on-disk
|
|
* or wire state on size changes needs its own setattr method.
|
|
*/
|
|
int simple_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
|
|
struct iattr *iattr)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
int error;
|
|
|
|
error = setattr_prepare(idmap, dentry, iattr);
|
|
if (error)
|
|
return error;
|
|
|
|
if (iattr->ia_valid & ATTR_SIZE)
|
|
truncate_setsize(inode, iattr->ia_size);
|
|
setattr_copy(idmap, inode, iattr);
|
|
mark_inode_dirty(inode);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(simple_setattr);
|
|
|
|
static int simple_read_folio(struct file *file, struct folio *folio)
|
|
{
|
|
folio_zero_range(folio, 0, folio_size(folio));
|
|
flush_dcache_folio(folio);
|
|
folio_mark_uptodate(folio);
|
|
folio_unlock(folio);
|
|
return 0;
|
|
}
|
|
|
|
int simple_write_begin(struct file *file, struct address_space *mapping,
|
|
loff_t pos, unsigned len,
|
|
struct page **pagep, void **fsdata)
|
|
{
|
|
struct folio *folio;
|
|
|
|
folio = __filemap_get_folio(mapping, pos / PAGE_SIZE, FGP_WRITEBEGIN,
|
|
mapping_gfp_mask(mapping));
|
|
if (IS_ERR(folio))
|
|
return PTR_ERR(folio);
|
|
|
|
*pagep = &folio->page;
|
|
|
|
if (!folio_test_uptodate(folio) && (len != folio_size(folio))) {
|
|
size_t from = offset_in_folio(folio, pos);
|
|
|
|
folio_zero_segments(folio, 0, from,
|
|
from + len, folio_size(folio));
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(simple_write_begin);
|
|
|
|
/**
|
|
* simple_write_end - .write_end helper for non-block-device FSes
|
|
* @file: See .write_end of address_space_operations
|
|
* @mapping: "
|
|
* @pos: "
|
|
* @len: "
|
|
* @copied: "
|
|
* @page: "
|
|
* @fsdata: "
|
|
*
|
|
* simple_write_end does the minimum needed for updating a page after writing is
|
|
* done. It has the same API signature as the .write_end of
|
|
* address_space_operations vector. So it can just be set onto .write_end for
|
|
* FSes that don't need any other processing. i_mutex is assumed to be held.
|
|
* Block based filesystems should use generic_write_end().
|
|
* NOTE: Even though i_size might get updated by this function, mark_inode_dirty
|
|
* is not called, so a filesystem that actually does store data in .write_inode
|
|
* should extend on what's done here with a call to mark_inode_dirty() in the
|
|
* case that i_size has changed.
|
|
*
|
|
* Use *ONLY* with simple_read_folio()
|
|
*/
|
|
static int simple_write_end(struct file *file, struct address_space *mapping,
|
|
loff_t pos, unsigned len, unsigned copied,
|
|
struct page *page, void *fsdata)
|
|
{
|
|
struct folio *folio = page_folio(page);
|
|
struct inode *inode = folio->mapping->host;
|
|
loff_t last_pos = pos + copied;
|
|
|
|
/* zero the stale part of the folio if we did a short copy */
|
|
if (!folio_test_uptodate(folio)) {
|
|
if (copied < len) {
|
|
size_t from = offset_in_folio(folio, pos);
|
|
|
|
folio_zero_range(folio, from + copied, len - copied);
|
|
}
|
|
folio_mark_uptodate(folio);
|
|
}
|
|
/*
|
|
* No need to use i_size_read() here, the i_size
|
|
* cannot change under us because we hold the i_mutex.
|
|
*/
|
|
if (last_pos > inode->i_size)
|
|
i_size_write(inode, last_pos);
|
|
|
|
folio_mark_dirty(folio);
|
|
folio_unlock(folio);
|
|
folio_put(folio);
|
|
|
|
return copied;
|
|
}
|
|
|
|
/*
|
|
* Provides ramfs-style behavior: data in the pagecache, but no writeback.
|
|
*/
|
|
const struct address_space_operations ram_aops = {
|
|
.read_folio = simple_read_folio,
|
|
.write_begin = simple_write_begin,
|
|
.write_end = simple_write_end,
|
|
.dirty_folio = noop_dirty_folio,
|
|
};
|
|
EXPORT_SYMBOL(ram_aops);
|
|
|
|
/*
|
|
* the inodes created here are not hashed. If you use iunique to generate
|
|
* unique inode values later for this filesystem, then you must take care
|
|
* to pass it an appropriate max_reserved value to avoid collisions.
|
|
*/
|
|
int simple_fill_super(struct super_block *s, unsigned long magic,
|
|
const struct tree_descr *files)
|
|
{
|
|
struct inode *inode;
|
|
struct dentry *dentry;
|
|
int i;
|
|
|
|
s->s_blocksize = PAGE_SIZE;
|
|
s->s_blocksize_bits = PAGE_SHIFT;
|
|
s->s_magic = magic;
|
|
s->s_op = &simple_super_operations;
|
|
s->s_time_gran = 1;
|
|
|
|
inode = new_inode(s);
|
|
if (!inode)
|
|
return -ENOMEM;
|
|
/*
|
|
* because the root inode is 1, the files array must not contain an
|
|
* entry at index 1
|
|
*/
|
|
inode->i_ino = 1;
|
|
inode->i_mode = S_IFDIR | 0755;
|
|
simple_inode_init_ts(inode);
|
|
inode->i_op = &simple_dir_inode_operations;
|
|
inode->i_fop = &simple_dir_operations;
|
|
set_nlink(inode, 2);
|
|
s->s_root = d_make_root(inode);
|
|
if (!s->s_root)
|
|
return -ENOMEM;
|
|
for (i = 0; !files->name || files->name[0]; i++, files++) {
|
|
if (!files->name)
|
|
continue;
|
|
|
|
/* warn if it tries to conflict with the root inode */
|
|
if (unlikely(i == 1))
|
|
printk(KERN_WARNING "%s: %s passed in a files array"
|
|
"with an index of 1!\n", __func__,
|
|
s->s_type->name);
|
|
|
|
dentry = d_alloc_name(s->s_root, files->name);
|
|
if (!dentry)
|
|
return -ENOMEM;
|
|
inode = new_inode(s);
|
|
if (!inode) {
|
|
dput(dentry);
|
|
return -ENOMEM;
|
|
}
|
|
inode->i_mode = S_IFREG | files->mode;
|
|
simple_inode_init_ts(inode);
|
|
inode->i_fop = files->ops;
|
|
inode->i_ino = i;
|
|
d_add(dentry, inode);
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(simple_fill_super);
|
|
|
|
static DEFINE_SPINLOCK(pin_fs_lock);
|
|
|
|
int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
|
|
{
|
|
struct vfsmount *mnt = NULL;
|
|
spin_lock(&pin_fs_lock);
|
|
if (unlikely(!*mount)) {
|
|
spin_unlock(&pin_fs_lock);
|
|
mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
|
|
if (IS_ERR(mnt))
|
|
return PTR_ERR(mnt);
|
|
spin_lock(&pin_fs_lock);
|
|
if (!*mount)
|
|
*mount = mnt;
|
|
}
|
|
mntget(*mount);
|
|
++*count;
|
|
spin_unlock(&pin_fs_lock);
|
|
mntput(mnt);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(simple_pin_fs);
|
|
|
|
void simple_release_fs(struct vfsmount **mount, int *count)
|
|
{
|
|
struct vfsmount *mnt;
|
|
spin_lock(&pin_fs_lock);
|
|
mnt = *mount;
|
|
if (!--*count)
|
|
*mount = NULL;
|
|
spin_unlock(&pin_fs_lock);
|
|
mntput(mnt);
|
|
}
|
|
EXPORT_SYMBOL(simple_release_fs);
|
|
|
|
/**
|
|
* simple_read_from_buffer - copy data from the buffer to user space
|
|
* @to: the user space buffer to read to
|
|
* @count: the maximum number of bytes to read
|
|
* @ppos: the current position in the buffer
|
|
* @from: the buffer to read from
|
|
* @available: the size of the buffer
|
|
*
|
|
* The simple_read_from_buffer() function reads up to @count bytes from the
|
|
* buffer @from at offset @ppos into the user space address starting at @to.
|
|
*
|
|
* On success, the number of bytes read is returned and the offset @ppos is
|
|
* advanced by this number, or negative value is returned on error.
|
|
**/
|
|
ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
|
|
const void *from, size_t available)
|
|
{
|
|
loff_t pos = *ppos;
|
|
size_t ret;
|
|
|
|
if (pos < 0)
|
|
return -EINVAL;
|
|
if (pos >= available || !count)
|
|
return 0;
|
|
if (count > available - pos)
|
|
count = available - pos;
|
|
ret = copy_to_user(to, from + pos, count);
|
|
if (ret == count)
|
|
return -EFAULT;
|
|
count -= ret;
|
|
*ppos = pos + count;
|
|
return count;
|
|
}
|
|
EXPORT_SYMBOL(simple_read_from_buffer);
|
|
|
|
/**
|
|
* simple_write_to_buffer - copy data from user space to the buffer
|
|
* @to: the buffer to write to
|
|
* @available: the size of the buffer
|
|
* @ppos: the current position in the buffer
|
|
* @from: the user space buffer to read from
|
|
* @count: the maximum number of bytes to read
|
|
*
|
|
* The simple_write_to_buffer() function reads up to @count bytes from the user
|
|
* space address starting at @from into the buffer @to at offset @ppos.
|
|
*
|
|
* On success, the number of bytes written is returned and the offset @ppos is
|
|
* advanced by this number, or negative value is returned on error.
|
|
**/
|
|
ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
|
|
const void __user *from, size_t count)
|
|
{
|
|
loff_t pos = *ppos;
|
|
size_t res;
|
|
|
|
if (pos < 0)
|
|
return -EINVAL;
|
|
if (pos >= available || !count)
|
|
return 0;
|
|
if (count > available - pos)
|
|
count = available - pos;
|
|
res = copy_from_user(to + pos, from, count);
|
|
if (res == count)
|
|
return -EFAULT;
|
|
count -= res;
|
|
*ppos = pos + count;
|
|
return count;
|
|
}
|
|
EXPORT_SYMBOL(simple_write_to_buffer);
|
|
|
|
/**
|
|
* memory_read_from_buffer - copy data from the buffer
|
|
* @to: the kernel space buffer to read to
|
|
* @count: the maximum number of bytes to read
|
|
* @ppos: the current position in the buffer
|
|
* @from: the buffer to read from
|
|
* @available: the size of the buffer
|
|
*
|
|
* The memory_read_from_buffer() function reads up to @count bytes from the
|
|
* buffer @from at offset @ppos into the kernel space address starting at @to.
|
|
*
|
|
* On success, the number of bytes read is returned and the offset @ppos is
|
|
* advanced by this number, or negative value is returned on error.
|
|
**/
|
|
ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
|
|
const void *from, size_t available)
|
|
{
|
|
loff_t pos = *ppos;
|
|
|
|
if (pos < 0)
|
|
return -EINVAL;
|
|
if (pos >= available)
|
|
return 0;
|
|
if (count > available - pos)
|
|
count = available - pos;
|
|
memcpy(to, from + pos, count);
|
|
*ppos = pos + count;
|
|
|
|
return count;
|
|
}
|
|
EXPORT_SYMBOL(memory_read_from_buffer);
|
|
|
|
/*
|
|
* Transaction based IO.
|
|
* The file expects a single write which triggers the transaction, and then
|
|
* possibly a read which collects the result - which is stored in a
|
|
* file-local buffer.
|
|
*/
|
|
|
|
void simple_transaction_set(struct file *file, size_t n)
|
|
{
|
|
struct simple_transaction_argresp *ar = file->private_data;
|
|
|
|
BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
|
|
|
|
/*
|
|
* The barrier ensures that ar->size will really remain zero until
|
|
* ar->data is ready for reading.
|
|
*/
|
|
smp_mb();
|
|
ar->size = n;
|
|
}
|
|
EXPORT_SYMBOL(simple_transaction_set);
|
|
|
|
char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
|
|
{
|
|
struct simple_transaction_argresp *ar;
|
|
static DEFINE_SPINLOCK(simple_transaction_lock);
|
|
|
|
if (size > SIMPLE_TRANSACTION_LIMIT - 1)
|
|
return ERR_PTR(-EFBIG);
|
|
|
|
ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
|
|
if (!ar)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
spin_lock(&simple_transaction_lock);
|
|
|
|
/* only one write allowed per open */
|
|
if (file->private_data) {
|
|
spin_unlock(&simple_transaction_lock);
|
|
free_page((unsigned long)ar);
|
|
return ERR_PTR(-EBUSY);
|
|
}
|
|
|
|
file->private_data = ar;
|
|
|
|
spin_unlock(&simple_transaction_lock);
|
|
|
|
if (copy_from_user(ar->data, buf, size))
|
|
return ERR_PTR(-EFAULT);
|
|
|
|
return ar->data;
|
|
}
|
|
EXPORT_SYMBOL(simple_transaction_get);
|
|
|
|
ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
|
|
{
|
|
struct simple_transaction_argresp *ar = file->private_data;
|
|
|
|
if (!ar)
|
|
return 0;
|
|
return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
|
|
}
|
|
EXPORT_SYMBOL(simple_transaction_read);
|
|
|
|
int simple_transaction_release(struct inode *inode, struct file *file)
|
|
{
|
|
free_page((unsigned long)file->private_data);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(simple_transaction_release);
|
|
|
|
/* Simple attribute files */
|
|
|
|
struct simple_attr {
|
|
int (*get)(void *, u64 *);
|
|
int (*set)(void *, u64);
|
|
char get_buf[24]; /* enough to store a u64 and "\n\0" */
|
|
char set_buf[24];
|
|
void *data;
|
|
const char *fmt; /* format for read operation */
|
|
struct mutex mutex; /* protects access to these buffers */
|
|
};
|
|
|
|
/* simple_attr_open is called by an actual attribute open file operation
|
|
* to set the attribute specific access operations. */
|
|
int simple_attr_open(struct inode *inode, struct file *file,
|
|
int (*get)(void *, u64 *), int (*set)(void *, u64),
|
|
const char *fmt)
|
|
{
|
|
struct simple_attr *attr;
|
|
|
|
attr = kzalloc(sizeof(*attr), GFP_KERNEL);
|
|
if (!attr)
|
|
return -ENOMEM;
|
|
|
|
attr->get = get;
|
|
attr->set = set;
|
|
attr->data = inode->i_private;
|
|
attr->fmt = fmt;
|
|
mutex_init(&attr->mutex);
|
|
|
|
file->private_data = attr;
|
|
|
|
return nonseekable_open(inode, file);
|
|
}
|
|
EXPORT_SYMBOL_GPL(simple_attr_open);
|
|
|
|
int simple_attr_release(struct inode *inode, struct file *file)
|
|
{
|
|
kfree(file->private_data);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
|
|
|
|
/* read from the buffer that is filled with the get function */
|
|
ssize_t simple_attr_read(struct file *file, char __user *buf,
|
|
size_t len, loff_t *ppos)
|
|
{
|
|
struct simple_attr *attr;
|
|
size_t size;
|
|
ssize_t ret;
|
|
|
|
attr = file->private_data;
|
|
|
|
if (!attr->get)
|
|
return -EACCES;
|
|
|
|
ret = mutex_lock_interruptible(&attr->mutex);
|
|
if (ret)
|
|
return ret;
|
|
|
|
if (*ppos && attr->get_buf[0]) {
|
|
/* continued read */
|
|
size = strlen(attr->get_buf);
|
|
} else {
|
|
/* first read */
|
|
u64 val;
|
|
ret = attr->get(attr->data, &val);
|
|
if (ret)
|
|
goto out;
|
|
|
|
size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
|
|
attr->fmt, (unsigned long long)val);
|
|
}
|
|
|
|
ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
|
|
out:
|
|
mutex_unlock(&attr->mutex);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(simple_attr_read);
|
|
|
|
/* interpret the buffer as a number to call the set function with */
|
|
static ssize_t simple_attr_write_xsigned(struct file *file, const char __user *buf,
|
|
size_t len, loff_t *ppos, bool is_signed)
|
|
{
|
|
struct simple_attr *attr;
|
|
unsigned long long val;
|
|
size_t size;
|
|
ssize_t ret;
|
|
|
|
attr = file->private_data;
|
|
if (!attr->set)
|
|
return -EACCES;
|
|
|
|
ret = mutex_lock_interruptible(&attr->mutex);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = -EFAULT;
|
|
size = min(sizeof(attr->set_buf) - 1, len);
|
|
if (copy_from_user(attr->set_buf, buf, size))
|
|
goto out;
|
|
|
|
attr->set_buf[size] = '\0';
|
|
if (is_signed)
|
|
ret = kstrtoll(attr->set_buf, 0, &val);
|
|
else
|
|
ret = kstrtoull(attr->set_buf, 0, &val);
|
|
if (ret)
|
|
goto out;
|
|
ret = attr->set(attr->data, val);
|
|
if (ret == 0)
|
|
ret = len; /* on success, claim we got the whole input */
|
|
out:
|
|
mutex_unlock(&attr->mutex);
|
|
return ret;
|
|
}
|
|
|
|
ssize_t simple_attr_write(struct file *file, const char __user *buf,
|
|
size_t len, loff_t *ppos)
|
|
{
|
|
return simple_attr_write_xsigned(file, buf, len, ppos, false);
|
|
}
|
|
EXPORT_SYMBOL_GPL(simple_attr_write);
|
|
|
|
ssize_t simple_attr_write_signed(struct file *file, const char __user *buf,
|
|
size_t len, loff_t *ppos)
|
|
{
|
|
return simple_attr_write_xsigned(file, buf, len, ppos, true);
|
|
}
|
|
EXPORT_SYMBOL_GPL(simple_attr_write_signed);
|
|
|
|
/**
|
|
* generic_encode_ino32_fh - generic export_operations->encode_fh function
|
|
* @inode: the object to encode
|
|
* @fh: where to store the file handle fragment
|
|
* @max_len: maximum length to store there (in 4 byte units)
|
|
* @parent: parent directory inode, if wanted
|
|
*
|
|
* This generic encode_fh function assumes that the 32 inode number
|
|
* is suitable for locating an inode, and that the generation number
|
|
* can be used to check that it is still valid. It places them in the
|
|
* filehandle fragment where export_decode_fh expects to find them.
|
|
*/
|
|
int generic_encode_ino32_fh(struct inode *inode, __u32 *fh, int *max_len,
|
|
struct inode *parent)
|
|
{
|
|
struct fid *fid = (void *)fh;
|
|
int len = *max_len;
|
|
int type = FILEID_INO32_GEN;
|
|
|
|
if (parent && (len < 4)) {
|
|
*max_len = 4;
|
|
return FILEID_INVALID;
|
|
} else if (len < 2) {
|
|
*max_len = 2;
|
|
return FILEID_INVALID;
|
|
}
|
|
|
|
len = 2;
|
|
fid->i32.ino = inode->i_ino;
|
|
fid->i32.gen = inode->i_generation;
|
|
if (parent) {
|
|
fid->i32.parent_ino = parent->i_ino;
|
|
fid->i32.parent_gen = parent->i_generation;
|
|
len = 4;
|
|
type = FILEID_INO32_GEN_PARENT;
|
|
}
|
|
*max_len = len;
|
|
return type;
|
|
}
|
|
EXPORT_SYMBOL_GPL(generic_encode_ino32_fh);
|
|
|
|
/**
|
|
* generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
|
|
* @sb: filesystem to do the file handle conversion on
|
|
* @fid: file handle to convert
|
|
* @fh_len: length of the file handle in bytes
|
|
* @fh_type: type of file handle
|
|
* @get_inode: filesystem callback to retrieve inode
|
|
*
|
|
* This function decodes @fid as long as it has one of the well-known
|
|
* Linux filehandle types and calls @get_inode on it to retrieve the
|
|
* inode for the object specified in the file handle.
|
|
*/
|
|
struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
|
|
int fh_len, int fh_type, struct inode *(*get_inode)
|
|
(struct super_block *sb, u64 ino, u32 gen))
|
|
{
|
|
struct inode *inode = NULL;
|
|
|
|
if (fh_len < 2)
|
|
return NULL;
|
|
|
|
switch (fh_type) {
|
|
case FILEID_INO32_GEN:
|
|
case FILEID_INO32_GEN_PARENT:
|
|
inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
|
|
break;
|
|
}
|
|
|
|
return d_obtain_alias(inode);
|
|
}
|
|
EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
|
|
|
|
/**
|
|
* generic_fh_to_parent - generic helper for the fh_to_parent export operation
|
|
* @sb: filesystem to do the file handle conversion on
|
|
* @fid: file handle to convert
|
|
* @fh_len: length of the file handle in bytes
|
|
* @fh_type: type of file handle
|
|
* @get_inode: filesystem callback to retrieve inode
|
|
*
|
|
* This function decodes @fid as long as it has one of the well-known
|
|
* Linux filehandle types and calls @get_inode on it to retrieve the
|
|
* inode for the _parent_ object specified in the file handle if it
|
|
* is specified in the file handle, or NULL otherwise.
|
|
*/
|
|
struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
|
|
int fh_len, int fh_type, struct inode *(*get_inode)
|
|
(struct super_block *sb, u64 ino, u32 gen))
|
|
{
|
|
struct inode *inode = NULL;
|
|
|
|
if (fh_len <= 2)
|
|
return NULL;
|
|
|
|
switch (fh_type) {
|
|
case FILEID_INO32_GEN_PARENT:
|
|
inode = get_inode(sb, fid->i32.parent_ino,
|
|
(fh_len > 3 ? fid->i32.parent_gen : 0));
|
|
break;
|
|
}
|
|
|
|
return d_obtain_alias(inode);
|
|
}
|
|
EXPORT_SYMBOL_GPL(generic_fh_to_parent);
|
|
|
|
/**
|
|
* __generic_file_fsync - generic fsync implementation for simple filesystems
|
|
*
|
|
* @file: file to synchronize
|
|
* @start: start offset in bytes
|
|
* @end: end offset in bytes (inclusive)
|
|
* @datasync: only synchronize essential metadata if true
|
|
*
|
|
* This is a generic implementation of the fsync method for simple
|
|
* filesystems which track all non-inode metadata in the buffers list
|
|
* hanging off the address_space structure.
|
|
*/
|
|
int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
|
|
int datasync)
|
|
{
|
|
struct inode *inode = file->f_mapping->host;
|
|
int err;
|
|
int ret;
|
|
|
|
err = file_write_and_wait_range(file, start, end);
|
|
if (err)
|
|
return err;
|
|
|
|
inode_lock(inode);
|
|
ret = sync_mapping_buffers(inode->i_mapping);
|
|
if (!(inode->i_state & I_DIRTY_ALL))
|
|
goto out;
|
|
if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
|
|
goto out;
|
|
|
|
err = sync_inode_metadata(inode, 1);
|
|
if (ret == 0)
|
|
ret = err;
|
|
|
|
out:
|
|
inode_unlock(inode);
|
|
/* check and advance again to catch errors after syncing out buffers */
|
|
err = file_check_and_advance_wb_err(file);
|
|
if (ret == 0)
|
|
ret = err;
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(__generic_file_fsync);
|
|
|
|
/**
|
|
* generic_file_fsync - generic fsync implementation for simple filesystems
|
|
* with flush
|
|
* @file: file to synchronize
|
|
* @start: start offset in bytes
|
|
* @end: end offset in bytes (inclusive)
|
|
* @datasync: only synchronize essential metadata if true
|
|
*
|
|
*/
|
|
|
|
int generic_file_fsync(struct file *file, loff_t start, loff_t end,
|
|
int datasync)
|
|
{
|
|
struct inode *inode = file->f_mapping->host;
|
|
int err;
|
|
|
|
err = __generic_file_fsync(file, start, end, datasync);
|
|
if (err)
|
|
return err;
|
|
return blkdev_issue_flush(inode->i_sb->s_bdev);
|
|
}
|
|
EXPORT_SYMBOL(generic_file_fsync);
|
|
|
|
/**
|
|
* generic_check_addressable - Check addressability of file system
|
|
* @blocksize_bits: log of file system block size
|
|
* @num_blocks: number of blocks in file system
|
|
*
|
|
* Determine whether a file system with @num_blocks blocks (and a
|
|
* block size of 2**@blocksize_bits) is addressable by the sector_t
|
|
* and page cache of the system. Return 0 if so and -EFBIG otherwise.
|
|
*/
|
|
int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
|
|
{
|
|
u64 last_fs_block = num_blocks - 1;
|
|
u64 last_fs_page =
|
|
last_fs_block >> (PAGE_SHIFT - blocksize_bits);
|
|
|
|
if (unlikely(num_blocks == 0))
|
|
return 0;
|
|
|
|
if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
|
|
return -EINVAL;
|
|
|
|
if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
|
|
(last_fs_page > (pgoff_t)(~0ULL))) {
|
|
return -EFBIG;
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(generic_check_addressable);
|
|
|
|
/*
|
|
* No-op implementation of ->fsync for in-memory filesystems.
|
|
*/
|
|
int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
|
|
{
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(noop_fsync);
|
|
|
|
ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
|
|
{
|
|
/*
|
|
* iomap based filesystems support direct I/O without need for
|
|
* this callback. However, it still needs to be set in
|
|
* inode->a_ops so that open/fcntl know that direct I/O is
|
|
* generally supported.
|
|
*/
|
|
return -EINVAL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(noop_direct_IO);
|
|
|
|
/* Because kfree isn't assignment-compatible with void(void*) ;-/ */
|
|
void kfree_link(void *p)
|
|
{
|
|
kfree(p);
|
|
}
|
|
EXPORT_SYMBOL(kfree_link);
|
|
|
|
struct inode *alloc_anon_inode(struct super_block *s)
|
|
{
|
|
static const struct address_space_operations anon_aops = {
|
|
.dirty_folio = noop_dirty_folio,
|
|
};
|
|
struct inode *inode = new_inode_pseudo(s);
|
|
|
|
if (!inode)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
inode->i_ino = get_next_ino();
|
|
inode->i_mapping->a_ops = &anon_aops;
|
|
|
|
/*
|
|
* Mark the inode dirty from the very beginning,
|
|
* that way it will never be moved to the dirty
|
|
* list because mark_inode_dirty() will think
|
|
* that it already _is_ on the dirty list.
|
|
*/
|
|
inode->i_state = I_DIRTY;
|
|
inode->i_mode = S_IRUSR | S_IWUSR;
|
|
inode->i_uid = current_fsuid();
|
|
inode->i_gid = current_fsgid();
|
|
inode->i_flags |= S_PRIVATE;
|
|
simple_inode_init_ts(inode);
|
|
return inode;
|
|
}
|
|
EXPORT_SYMBOL(alloc_anon_inode);
|
|
|
|
/**
|
|
* simple_nosetlease - generic helper for prohibiting leases
|
|
* @filp: file pointer
|
|
* @arg: type of lease to obtain
|
|
* @flp: new lease supplied for insertion
|
|
* @priv: private data for lm_setup operation
|
|
*
|
|
* Generic helper for filesystems that do not wish to allow leases to be set.
|
|
* All arguments are ignored and it just returns -EINVAL.
|
|
*/
|
|
int
|
|
simple_nosetlease(struct file *filp, int arg, struct file_lease **flp,
|
|
void **priv)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
EXPORT_SYMBOL(simple_nosetlease);
|
|
|
|
/**
|
|
* simple_get_link - generic helper to get the target of "fast" symlinks
|
|
* @dentry: not used here
|
|
* @inode: the symlink inode
|
|
* @done: not used here
|
|
*
|
|
* Generic helper for filesystems to use for symlink inodes where a pointer to
|
|
* the symlink target is stored in ->i_link. NOTE: this isn't normally called,
|
|
* since as an optimization the path lookup code uses any non-NULL ->i_link
|
|
* directly, without calling ->get_link(). But ->get_link() still must be set,
|
|
* to mark the inode_operations as being for a symlink.
|
|
*
|
|
* Return: the symlink target
|
|
*/
|
|
const char *simple_get_link(struct dentry *dentry, struct inode *inode,
|
|
struct delayed_call *done)
|
|
{
|
|
return inode->i_link;
|
|
}
|
|
EXPORT_SYMBOL(simple_get_link);
|
|
|
|
const struct inode_operations simple_symlink_inode_operations = {
|
|
.get_link = simple_get_link,
|
|
};
|
|
EXPORT_SYMBOL(simple_symlink_inode_operations);
|
|
|
|
/*
|
|
* Operations for a permanently empty directory.
|
|
*/
|
|
static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
|
|
{
|
|
return ERR_PTR(-ENOENT);
|
|
}
|
|
|
|
static int empty_dir_getattr(struct mnt_idmap *idmap,
|
|
const struct path *path, struct kstat *stat,
|
|
u32 request_mask, unsigned int query_flags)
|
|
{
|
|
struct inode *inode = d_inode(path->dentry);
|
|
generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
|
|
return 0;
|
|
}
|
|
|
|
static int empty_dir_setattr(struct mnt_idmap *idmap,
|
|
struct dentry *dentry, struct iattr *attr)
|
|
{
|
|
return -EPERM;
|
|
}
|
|
|
|
static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size)
|
|
{
|
|
return -EOPNOTSUPP;
|
|
}
|
|
|
|
static const struct inode_operations empty_dir_inode_operations = {
|
|
.lookup = empty_dir_lookup,
|
|
.permission = generic_permission,
|
|
.setattr = empty_dir_setattr,
|
|
.getattr = empty_dir_getattr,
|
|
.listxattr = empty_dir_listxattr,
|
|
};
|
|
|
|
static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence)
|
|
{
|
|
/* An empty directory has two entries . and .. at offsets 0 and 1 */
|
|
return generic_file_llseek_size(file, offset, whence, 2, 2);
|
|
}
|
|
|
|
static int empty_dir_readdir(struct file *file, struct dir_context *ctx)
|
|
{
|
|
dir_emit_dots(file, ctx);
|
|
return 0;
|
|
}
|
|
|
|
static const struct file_operations empty_dir_operations = {
|
|
.llseek = empty_dir_llseek,
|
|
.read = generic_read_dir,
|
|
.iterate_shared = empty_dir_readdir,
|
|
.fsync = noop_fsync,
|
|
};
|
|
|
|
|
|
void make_empty_dir_inode(struct inode *inode)
|
|
{
|
|
set_nlink(inode, 2);
|
|
inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
|
|
inode->i_uid = GLOBAL_ROOT_UID;
|
|
inode->i_gid = GLOBAL_ROOT_GID;
|
|
inode->i_rdev = 0;
|
|
inode->i_size = 0;
|
|
inode->i_blkbits = PAGE_SHIFT;
|
|
inode->i_blocks = 0;
|
|
|
|
inode->i_op = &empty_dir_inode_operations;
|
|
inode->i_opflags &= ~IOP_XATTR;
|
|
inode->i_fop = &empty_dir_operations;
|
|
}
|
|
|
|
bool is_empty_dir_inode(struct inode *inode)
|
|
{
|
|
return (inode->i_fop == &empty_dir_operations) &&
|
|
(inode->i_op == &empty_dir_inode_operations);
|
|
}
|
|
|
|
#if IS_ENABLED(CONFIG_UNICODE)
|
|
/**
|
|
* generic_ci_d_compare - generic d_compare implementation for casefolding filesystems
|
|
* @dentry: dentry whose name we are checking against
|
|
* @len: len of name of dentry
|
|
* @str: str pointer to name of dentry
|
|
* @name: Name to compare against
|
|
*
|
|
* Return: 0 if names match, 1 if mismatch, or -ERRNO
|
|
*/
|
|
static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
|
|
const char *str, const struct qstr *name)
|
|
{
|
|
const struct dentry *parent;
|
|
const struct inode *dir;
|
|
char strbuf[DNAME_INLINE_LEN];
|
|
struct qstr qstr;
|
|
|
|
/*
|
|
* Attempt a case-sensitive match first. It is cheaper and
|
|
* should cover most lookups, including all the sane
|
|
* applications that expect a case-sensitive filesystem.
|
|
*
|
|
* This comparison is safe under RCU because the caller
|
|
* guarantees the consistency between str and len. See
|
|
* __d_lookup_rcu_op_compare() for details.
|
|
*/
|
|
if (len == name->len && !memcmp(str, name->name, len))
|
|
return 0;
|
|
|
|
parent = READ_ONCE(dentry->d_parent);
|
|
dir = READ_ONCE(parent->d_inode);
|
|
if (!dir || !IS_CASEFOLDED(dir))
|
|
return 1;
|
|
|
|
/*
|
|
* If the dentry name is stored in-line, then it may be concurrently
|
|
* modified by a rename. If this happens, the VFS will eventually retry
|
|
* the lookup, so it doesn't matter what ->d_compare() returns.
|
|
* However, it's unsafe to call utf8_strncasecmp() with an unstable
|
|
* string. Therefore, we have to copy the name into a temporary buffer.
|
|
*/
|
|
if (len <= DNAME_INLINE_LEN - 1) {
|
|
memcpy(strbuf, str, len);
|
|
strbuf[len] = 0;
|
|
str = strbuf;
|
|
/* prevent compiler from optimizing out the temporary buffer */
|
|
barrier();
|
|
}
|
|
qstr.len = len;
|
|
qstr.name = str;
|
|
|
|
return utf8_strncasecmp(dentry->d_sb->s_encoding, name, &qstr);
|
|
}
|
|
|
|
/**
|
|
* generic_ci_d_hash - generic d_hash implementation for casefolding filesystems
|
|
* @dentry: dentry of the parent directory
|
|
* @str: qstr of name whose hash we should fill in
|
|
*
|
|
* Return: 0 if hash was successful or unchanged, and -EINVAL on error
|
|
*/
|
|
static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
|
|
{
|
|
const struct inode *dir = READ_ONCE(dentry->d_inode);
|
|
struct super_block *sb = dentry->d_sb;
|
|
const struct unicode_map *um = sb->s_encoding;
|
|
int ret;
|
|
|
|
if (!dir || !IS_CASEFOLDED(dir))
|
|
return 0;
|
|
|
|
ret = utf8_casefold_hash(um, dentry, str);
|
|
if (ret < 0 && sb_has_strict_encoding(sb))
|
|
return -EINVAL;
|
|
return 0;
|
|
}
|
|
|
|
static const struct dentry_operations generic_ci_dentry_ops = {
|
|
.d_hash = generic_ci_d_hash,
|
|
.d_compare = generic_ci_d_compare,
|
|
#ifdef CONFIG_FS_ENCRYPTION
|
|
.d_revalidate = fscrypt_d_revalidate,
|
|
#endif
|
|
};
|
|
#endif
|
|
|
|
#ifdef CONFIG_FS_ENCRYPTION
|
|
static const struct dentry_operations generic_encrypted_dentry_ops = {
|
|
.d_revalidate = fscrypt_d_revalidate,
|
|
};
|
|
#endif
|
|
|
|
/**
|
|
* generic_set_sb_d_ops - helper for choosing the set of
|
|
* filesystem-wide dentry operations for the enabled features
|
|
* @sb: superblock to be configured
|
|
*
|
|
* Filesystems supporting casefolding and/or fscrypt can call this
|
|
* helper at mount-time to configure sb->s_d_op to best set of dentry
|
|
* operations required for the enabled features. The helper must be
|
|
* called after these have been configured, but before the root dentry
|
|
* is created.
|
|
*/
|
|
void generic_set_sb_d_ops(struct super_block *sb)
|
|
{
|
|
#if IS_ENABLED(CONFIG_UNICODE)
|
|
if (sb->s_encoding) {
|
|
sb->s_d_op = &generic_ci_dentry_ops;
|
|
return;
|
|
}
|
|
#endif
|
|
#ifdef CONFIG_FS_ENCRYPTION
|
|
if (sb->s_cop) {
|
|
sb->s_d_op = &generic_encrypted_dentry_ops;
|
|
return;
|
|
}
|
|
#endif
|
|
}
|
|
EXPORT_SYMBOL(generic_set_sb_d_ops);
|
|
|
|
/**
|
|
* inode_maybe_inc_iversion - increments i_version
|
|
* @inode: inode with the i_version that should be updated
|
|
* @force: increment the counter even if it's not necessary?
|
|
*
|
|
* Every time the inode is modified, the i_version field must be seen to have
|
|
* changed by any observer.
|
|
*
|
|
* If "force" is set or the QUERIED flag is set, then ensure that we increment
|
|
* the value, and clear the queried flag.
|
|
*
|
|
* In the common case where neither is set, then we can return "false" without
|
|
* updating i_version.
|
|
*
|
|
* If this function returns false, and no other metadata has changed, then we
|
|
* can avoid logging the metadata.
|
|
*/
|
|
bool inode_maybe_inc_iversion(struct inode *inode, bool force)
|
|
{
|
|
u64 cur, new;
|
|
|
|
/*
|
|
* The i_version field is not strictly ordered with any other inode
|
|
* information, but the legacy inode_inc_iversion code used a spinlock
|
|
* to serialize increments.
|
|
*
|
|
* Here, we add full memory barriers to ensure that any de-facto
|
|
* ordering with other info is preserved.
|
|
*
|
|
* This barrier pairs with the barrier in inode_query_iversion()
|
|
*/
|
|
smp_mb();
|
|
cur = inode_peek_iversion_raw(inode);
|
|
do {
|
|
/* If flag is clear then we needn't do anything */
|
|
if (!force && !(cur & I_VERSION_QUERIED))
|
|
return false;
|
|
|
|
/* Since lowest bit is flag, add 2 to avoid it */
|
|
new = (cur & ~I_VERSION_QUERIED) + I_VERSION_INCREMENT;
|
|
} while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new));
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(inode_maybe_inc_iversion);
|
|
|
|
/**
|
|
* inode_query_iversion - read i_version for later use
|
|
* @inode: inode from which i_version should be read
|
|
*
|
|
* Read the inode i_version counter. This should be used by callers that wish
|
|
* to store the returned i_version for later comparison. This will guarantee
|
|
* that a later query of the i_version will result in a different value if
|
|
* anything has changed.
|
|
*
|
|
* In this implementation, we fetch the current value, set the QUERIED flag and
|
|
* then try to swap it into place with a cmpxchg, if it wasn't already set. If
|
|
* that fails, we try again with the newly fetched value from the cmpxchg.
|
|
*/
|
|
u64 inode_query_iversion(struct inode *inode)
|
|
{
|
|
u64 cur, new;
|
|
|
|
cur = inode_peek_iversion_raw(inode);
|
|
do {
|
|
/* If flag is already set, then no need to swap */
|
|
if (cur & I_VERSION_QUERIED) {
|
|
/*
|
|
* This barrier (and the implicit barrier in the
|
|
* cmpxchg below) pairs with the barrier in
|
|
* inode_maybe_inc_iversion().
|
|
*/
|
|
smp_mb();
|
|
break;
|
|
}
|
|
|
|
new = cur | I_VERSION_QUERIED;
|
|
} while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new));
|
|
return cur >> I_VERSION_QUERIED_SHIFT;
|
|
}
|
|
EXPORT_SYMBOL(inode_query_iversion);
|
|
|
|
ssize_t direct_write_fallback(struct kiocb *iocb, struct iov_iter *iter,
|
|
ssize_t direct_written, ssize_t buffered_written)
|
|
{
|
|
struct address_space *mapping = iocb->ki_filp->f_mapping;
|
|
loff_t pos = iocb->ki_pos - buffered_written;
|
|
loff_t end = iocb->ki_pos - 1;
|
|
int err;
|
|
|
|
/*
|
|
* If the buffered write fallback returned an error, we want to return
|
|
* the number of bytes which were written by direct I/O, or the error
|
|
* code if that was zero.
|
|
*
|
|
* Note that this differs from normal direct-io semantics, which will
|
|
* return -EFOO even if some bytes were written.
|
|
*/
|
|
if (unlikely(buffered_written < 0)) {
|
|
if (direct_written)
|
|
return direct_written;
|
|
return buffered_written;
|
|
}
|
|
|
|
/*
|
|
* We need to ensure that the page cache pages are written to disk and
|
|
* invalidated to preserve the expected O_DIRECT semantics.
|
|
*/
|
|
err = filemap_write_and_wait_range(mapping, pos, end);
|
|
if (err < 0) {
|
|
/*
|
|
* We don't know how much we wrote, so just return the number of
|
|
* bytes which were direct-written
|
|
*/
|
|
iocb->ki_pos -= buffered_written;
|
|
if (direct_written)
|
|
return direct_written;
|
|
return err;
|
|
}
|
|
invalidate_mapping_pages(mapping, pos >> PAGE_SHIFT, end >> PAGE_SHIFT);
|
|
return direct_written + buffered_written;
|
|
}
|
|
EXPORT_SYMBOL_GPL(direct_write_fallback);
|
|
|
|
/**
|
|
* simple_inode_init_ts - initialize the timestamps for a new inode
|
|
* @inode: inode to be initialized
|
|
*
|
|
* When a new inode is created, most filesystems set the timestamps to the
|
|
* current time. Add a helper to do this.
|
|
*/
|
|
struct timespec64 simple_inode_init_ts(struct inode *inode)
|
|
{
|
|
struct timespec64 ts = inode_set_ctime_current(inode);
|
|
|
|
inode_set_atime_to_ts(inode, ts);
|
|
inode_set_mtime_to_ts(inode, ts);
|
|
return ts;
|
|
}
|
|
EXPORT_SYMBOL(simple_inode_init_ts);
|
|
|
|
static inline struct dentry *get_stashed_dentry(struct dentry *stashed)
|
|
{
|
|
struct dentry *dentry;
|
|
|
|
guard(rcu)();
|
|
dentry = READ_ONCE(stashed);
|
|
if (!dentry)
|
|
return NULL;
|
|
if (!lockref_get_not_dead(&dentry->d_lockref))
|
|
return NULL;
|
|
return dentry;
|
|
}
|
|
|
|
static struct dentry *prepare_anon_dentry(struct dentry **stashed,
|
|
struct super_block *sb,
|
|
void *data)
|
|
{
|
|
struct dentry *dentry;
|
|
struct inode *inode;
|
|
const struct stashed_operations *sops = sb->s_fs_info;
|
|
int ret;
|
|
|
|
inode = new_inode_pseudo(sb);
|
|
if (!inode) {
|
|
sops->put_data(data);
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
|
|
inode->i_flags |= S_IMMUTABLE;
|
|
inode->i_mode = S_IFREG;
|
|
simple_inode_init_ts(inode);
|
|
|
|
ret = sops->init_inode(inode, data);
|
|
if (ret < 0) {
|
|
iput(inode);
|
|
return ERR_PTR(ret);
|
|
}
|
|
|
|
/* Notice when this is changed. */
|
|
WARN_ON_ONCE(!S_ISREG(inode->i_mode));
|
|
WARN_ON_ONCE(!IS_IMMUTABLE(inode));
|
|
|
|
dentry = d_alloc_anon(sb);
|
|
if (!dentry) {
|
|
iput(inode);
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
|
|
/* Store address of location where dentry's supposed to be stashed. */
|
|
dentry->d_fsdata = stashed;
|
|
|
|
/* @data is now owned by the fs */
|
|
d_instantiate(dentry, inode);
|
|
return dentry;
|
|
}
|
|
|
|
static struct dentry *stash_dentry(struct dentry **stashed,
|
|
struct dentry *dentry)
|
|
{
|
|
guard(rcu)();
|
|
for (;;) {
|
|
struct dentry *old;
|
|
|
|
/* Assume any old dentry was cleared out. */
|
|
old = cmpxchg(stashed, NULL, dentry);
|
|
if (likely(!old))
|
|
return dentry;
|
|
|
|
/* Check if somebody else installed a reusable dentry. */
|
|
if (lockref_get_not_dead(&old->d_lockref))
|
|
return old;
|
|
|
|
/* There's an old dead dentry there, try to take it over. */
|
|
if (likely(try_cmpxchg(stashed, &old, dentry)))
|
|
return dentry;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* path_from_stashed - create path from stashed or new dentry
|
|
* @stashed: where to retrieve or stash dentry
|
|
* @mnt: mnt of the filesystems to use
|
|
* @data: data to store in inode->i_private
|
|
* @path: path to create
|
|
*
|
|
* The function tries to retrieve a stashed dentry from @stashed. If the dentry
|
|
* is still valid then it will be reused. If the dentry isn't able the function
|
|
* will allocate a new dentry and inode. It will then check again whether it
|
|
* can reuse an existing dentry in case one has been added in the meantime or
|
|
* update @stashed with the newly added dentry.
|
|
*
|
|
* Special-purpose helper for nsfs and pidfs.
|
|
*
|
|
* Return: On success zero and on failure a negative error is returned.
|
|
*/
|
|
int path_from_stashed(struct dentry **stashed, struct vfsmount *mnt, void *data,
|
|
struct path *path)
|
|
{
|
|
struct dentry *dentry;
|
|
const struct stashed_operations *sops = mnt->mnt_sb->s_fs_info;
|
|
|
|
/* See if dentry can be reused. */
|
|
path->dentry = get_stashed_dentry(*stashed);
|
|
if (path->dentry) {
|
|
sops->put_data(data);
|
|
goto out_path;
|
|
}
|
|
|
|
/* Allocate a new dentry. */
|
|
dentry = prepare_anon_dentry(stashed, mnt->mnt_sb, data);
|
|
if (IS_ERR(dentry))
|
|
return PTR_ERR(dentry);
|
|
|
|
/* Added a new dentry. @data is now owned by the filesystem. */
|
|
path->dentry = stash_dentry(stashed, dentry);
|
|
if (path->dentry != dentry)
|
|
dput(dentry);
|
|
|
|
out_path:
|
|
WARN_ON_ONCE(path->dentry->d_fsdata != stashed);
|
|
WARN_ON_ONCE(d_inode(path->dentry)->i_private != data);
|
|
path->mnt = mntget(mnt);
|
|
return 0;
|
|
}
|
|
|
|
void stashed_dentry_prune(struct dentry *dentry)
|
|
{
|
|
struct dentry **stashed = dentry->d_fsdata;
|
|
struct inode *inode = d_inode(dentry);
|
|
|
|
if (WARN_ON_ONCE(!stashed))
|
|
return;
|
|
|
|
if (!inode)
|
|
return;
|
|
|
|
/*
|
|
* Only replace our own @dentry as someone else might've
|
|
* already cleared out @dentry and stashed their own
|
|
* dentry in there.
|
|
*/
|
|
cmpxchg(stashed, dentry, NULL);
|
|
}
|