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![Gustavo A. R. Silva](/assets/img/avatar_default.png)
Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
1365 lines
35 KiB
C
1365 lines
35 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/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/uaccess.h>
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#include "internal.h"
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int simple_getattr(const struct path *path, struct kstat *stat,
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u32 request_mask, 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(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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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 list_head *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 = p->next) != &dentry->d_subdirs) {
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struct dentry *d = list_entry(p, struct dentry, d_child);
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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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list_move(&cursor->d_child, p);
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p = &cursor->d_child;
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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_subdirs,
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offset - 2, NULL);
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spin_lock(&dentry->d_lock);
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if (to)
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list_move(&cursor->d_child, &to->d_child);
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else
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list_del_init(&cursor->d_child);
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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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/* Relationship between i_mode and the DT_xxx types */
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static inline unsigned char dt_type(struct inode *inode)
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{
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return (inode->i_mode >> 12) & 15;
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}
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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 list_head *anchor = &dentry->d_subdirs;
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struct dentry *next = NULL;
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struct list_head *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 = anchor;
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else if (!list_empty(&cursor->d_child))
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p = &cursor->d_child;
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else
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return 0;
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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, dt_type(d_inode(next))))
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break;
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ctx->pos++;
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p = &next->d_child;
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}
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spin_lock(&dentry->d_lock);
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if (next)
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list_move_tail(&cursor->d_child, &next->d_child);
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else
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list_del_init(&cursor->d_child);
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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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static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev)
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{
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struct dentry *child = NULL;
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struct list_head *p = prev ? &prev->d_child : &parent->d_subdirs;
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spin_lock(&parent->d_lock);
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while ((p = p->next) != &parent->d_subdirs) {
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struct dentry *d = container_of(p, struct dentry, d_child);
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if (simple_positive(d)) {
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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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child = dget_dlock(d);
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spin_unlock(&d->d_lock);
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if (likely(child))
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break;
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}
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}
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spin_unlock(&parent->d_lock);
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dput(prev);
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return child;
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}
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void simple_recursive_removal(struct dentry *dentry,
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void (*callback)(struct dentry *))
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{
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struct dentry *this = dget(dentry);
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while (true) {
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struct dentry *victim = NULL, *child;
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struct inode *inode = this->d_inode;
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inode_lock(inode);
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if (d_is_dir(this))
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inode->i_flags |= S_DEAD;
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while ((child = find_next_child(this, victim)) == NULL) {
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// kill and ascend
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// update metadata while it's still locked
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inode->i_ctime = current_time(inode);
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clear_nlink(inode);
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inode_unlock(inode);
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victim = this;
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this = this->d_parent;
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inode = this->d_inode;
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inode_lock(inode);
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if (simple_positive(victim)) {
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d_invalidate(victim); // avoid lost mounts
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if (d_is_dir(victim))
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fsnotify_rmdir(inode, victim);
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else
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fsnotify_unlink(inode, victim);
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if (callback)
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callback(victim);
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dput(victim); // unpin it
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}
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if (victim == dentry) {
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inode->i_ctime = inode->i_mtime =
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current_time(inode);
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if (d_is_dir(dentry))
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drop_nlink(inode);
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inode_unlock(inode);
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dput(dentry);
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return;
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}
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}
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inode_unlock(inode);
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this = child;
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}
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}
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EXPORT_SYMBOL(simple_recursive_removal);
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static const struct super_operations simple_super_operations = {
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.statfs = simple_statfs,
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};
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static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc)
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{
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struct pseudo_fs_context *ctx = fc->fs_private;
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struct inode *root;
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s->s_maxbytes = MAX_LFS_FILESIZE;
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s->s_blocksize = PAGE_SIZE;
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s->s_blocksize_bits = PAGE_SHIFT;
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s->s_magic = ctx->magic;
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s->s_op = ctx->ops ?: &simple_super_operations;
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s->s_xattr = ctx->xattr;
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s->s_time_gran = 1;
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root = new_inode(s);
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if (!root)
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return -ENOMEM;
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/*
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* since this is the first inode, make it number 1. New inodes created
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* after this must take care not to collide with it (by passing
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* max_reserved of 1 to iunique).
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*/
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root->i_ino = 1;
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root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
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root->i_atime = root->i_mtime = root->i_ctime = current_time(root);
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s->s_root = d_make_root(root);
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if (!s->s_root)
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return -ENOMEM;
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s->s_d_op = ctx->dops;
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return 0;
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}
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static int pseudo_fs_get_tree(struct fs_context *fc)
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{
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return get_tree_nodev(fc, pseudo_fs_fill_super);
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}
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static void pseudo_fs_free(struct fs_context *fc)
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{
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kfree(fc->fs_private);
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}
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static const struct fs_context_operations pseudo_fs_context_ops = {
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.free = pseudo_fs_free,
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.get_tree = pseudo_fs_get_tree,
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};
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/*
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* Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
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* will never be mountable)
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*/
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struct pseudo_fs_context *init_pseudo(struct fs_context *fc,
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unsigned long magic)
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{
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struct pseudo_fs_context *ctx;
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ctx = kzalloc(sizeof(struct pseudo_fs_context), GFP_KERNEL);
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if (likely(ctx)) {
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ctx->magic = magic;
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fc->fs_private = ctx;
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fc->ops = &pseudo_fs_context_ops;
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fc->sb_flags |= SB_NOUSER;
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fc->global = true;
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}
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return ctx;
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}
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EXPORT_SYMBOL(init_pseudo);
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int simple_open(struct inode *inode, struct file *file)
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{
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if (inode->i_private)
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file->private_data = inode->i_private;
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return 0;
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}
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EXPORT_SYMBOL(simple_open);
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int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
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{
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struct inode *inode = d_inode(old_dentry);
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inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
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inc_nlink(inode);
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ihold(inode);
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dget(dentry);
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d_instantiate(dentry, inode);
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return 0;
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}
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EXPORT_SYMBOL(simple_link);
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int simple_empty(struct dentry *dentry)
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{
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struct dentry *child;
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int ret = 0;
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spin_lock(&dentry->d_lock);
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list_for_each_entry(child, &dentry->d_subdirs, d_child) {
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spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
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if (simple_positive(child)) {
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spin_unlock(&child->d_lock);
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goto out;
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}
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spin_unlock(&child->d_lock);
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}
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ret = 1;
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out:
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spin_unlock(&dentry->d_lock);
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return ret;
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}
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EXPORT_SYMBOL(simple_empty);
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int simple_unlink(struct inode *dir, struct dentry *dentry)
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{
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struct inode *inode = d_inode(dentry);
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inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
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drop_nlink(inode);
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dput(dentry);
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return 0;
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}
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EXPORT_SYMBOL(simple_unlink);
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int simple_rmdir(struct inode *dir, struct dentry *dentry)
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{
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if (!simple_empty(dentry))
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return -ENOTEMPTY;
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drop_nlink(d_inode(dentry));
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simple_unlink(dir, dentry);
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drop_nlink(dir);
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return 0;
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}
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EXPORT_SYMBOL(simple_rmdir);
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int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
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struct inode *new_dir, struct dentry *new_dentry,
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unsigned int flags)
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{
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struct inode *inode = d_inode(old_dentry);
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int they_are_dirs = d_is_dir(old_dentry);
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|
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if (flags & ~RENAME_NOREPLACE)
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return -EINVAL;
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|
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if (!simple_empty(new_dentry))
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return -ENOTEMPTY;
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|
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if (d_really_is_positive(new_dentry)) {
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simple_unlink(new_dir, new_dentry);
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if (they_are_dirs) {
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drop_nlink(d_inode(new_dentry));
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drop_nlink(old_dir);
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}
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} else if (they_are_dirs) {
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drop_nlink(old_dir);
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inc_nlink(new_dir);
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}
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|
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old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
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new_dir->i_mtime = inode->i_ctime = current_time(old_dir);
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|
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return 0;
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}
|
|
EXPORT_SYMBOL(simple_rename);
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|
|
|
/**
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|
* simple_setattr - setattr for simple filesystem
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|
* @dentry: dentry
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* @iattr: iattr structure
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|
*
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* Returns 0 on success, -error on failure.
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*
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* simple_setattr is a simple ->setattr implementation without a proper
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* implementation of size changes.
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*
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* It can either be used for in-memory filesystems or special files
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|
* on simple regular filesystems. Anything that needs to change on-disk
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* or wire state on size changes needs its own setattr method.
|
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*/
|
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int simple_setattr(struct dentry *dentry, struct iattr *iattr)
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{
|
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struct inode *inode = d_inode(dentry);
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int error;
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|
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error = setattr_prepare(dentry, iattr);
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if (error)
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return error;
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|
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if (iattr->ia_valid & ATTR_SIZE)
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truncate_setsize(inode, iattr->ia_size);
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setattr_copy(inode, iattr);
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mark_inode_dirty(inode);
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return 0;
|
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}
|
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EXPORT_SYMBOL(simple_setattr);
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|
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int simple_readpage(struct file *file, struct page *page)
|
|
{
|
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clear_highpage(page);
|
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flush_dcache_page(page);
|
|
SetPageUptodate(page);
|
|
unlock_page(page);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(simple_readpage);
|
|
|
|
int simple_write_begin(struct file *file, struct address_space *mapping,
|
|
loff_t pos, unsigned len, unsigned flags,
|
|
struct page **pagep, void **fsdata)
|
|
{
|
|
struct page *page;
|
|
pgoff_t index;
|
|
|
|
index = pos >> PAGE_SHIFT;
|
|
|
|
page = grab_cache_page_write_begin(mapping, index, flags);
|
|
if (!page)
|
|
return -ENOMEM;
|
|
|
|
*pagep = page;
|
|
|
|
if (!PageUptodate(page) && (len != PAGE_SIZE)) {
|
|
unsigned from = pos & (PAGE_SIZE - 1);
|
|
|
|
zero_user_segments(page, 0, from, from + len, PAGE_SIZE);
|
|
}
|
|
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_readpage()
|
|
*/
|
|
int simple_write_end(struct file *file, struct address_space *mapping,
|
|
loff_t pos, unsigned len, unsigned copied,
|
|
struct page *page, void *fsdata)
|
|
{
|
|
struct inode *inode = page->mapping->host;
|
|
loff_t last_pos = pos + copied;
|
|
|
|
/* zero the stale part of the page if we did a short copy */
|
|
if (!PageUptodate(page)) {
|
|
if (copied < len) {
|
|
unsigned from = pos & (PAGE_SIZE - 1);
|
|
|
|
zero_user(page, from + copied, len - copied);
|
|
}
|
|
SetPageUptodate(page);
|
|
}
|
|
/*
|
|
* 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);
|
|
|
|
set_page_dirty(page);
|
|
unlock_page(page);
|
|
put_page(page);
|
|
|
|
return copied;
|
|
}
|
|
EXPORT_SYMBOL(simple_write_end);
|
|
|
|
/*
|
|
* 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 *root;
|
|
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;
|
|
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
|
|
inode->i_op = &simple_dir_inode_operations;
|
|
inode->i_fop = &simple_dir_operations;
|
|
set_nlink(inode, 2);
|
|
root = d_make_root(inode);
|
|
if (!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(root, files->name);
|
|
if (!dentry)
|
|
goto out;
|
|
inode = new_inode(s);
|
|
if (!inode) {
|
|
dput(dentry);
|
|
goto out;
|
|
}
|
|
inode->i_mode = S_IFREG | files->mode;
|
|
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
|
|
inode->i_fop = files->ops;
|
|
inode->i_ino = i;
|
|
d_add(dentry, inode);
|
|
}
|
|
s->s_root = root;
|
|
return 0;
|
|
out:
|
|
d_genocide(root);
|
|
shrink_dcache_parent(root);
|
|
dput(root);
|
|
return -ENOMEM;
|
|
}
|
|
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 */
|
|
ssize_t simple_attr_write(struct file *file, const char __user *buf,
|
|
size_t len, loff_t *ppos)
|
|
{
|
|
struct simple_attr *attr;
|
|
u64 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';
|
|
val = simple_strtoll(attr->set_buf, NULL, 0);
|
|
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;
|
|
}
|
|
EXPORT_SYMBOL_GPL(simple_attr_write);
|
|
|
|
/**
|
|
* 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, GFP_KERNEL);
|
|
}
|
|
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);
|
|
|
|
int noop_set_page_dirty(struct page *page)
|
|
{
|
|
/*
|
|
* Unlike __set_page_dirty_no_writeback that handles dirty page
|
|
* tracking in the page object, dax does all dirty tracking in
|
|
* the inode address_space in response to mkwrite faults. In the
|
|
* dax case we only need to worry about potentially dirty CPU
|
|
* caches, not dirty page cache pages to write back.
|
|
*
|
|
* This callback is defined to prevent fallback to
|
|
* __set_page_dirty_buffers() in set_page_dirty().
|
|
*/
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(noop_set_page_dirty);
|
|
|
|
void noop_invalidatepage(struct page *page, unsigned int offset,
|
|
unsigned int length)
|
|
{
|
|
/*
|
|
* There is no page cache to invalidate in the dax case, however
|
|
* we need this callback defined to prevent falling back to
|
|
* block_invalidatepage() in do_invalidatepage().
|
|
*/
|
|
}
|
|
EXPORT_SYMBOL_GPL(noop_invalidatepage);
|
|
|
|
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);
|
|
|
|
/*
|
|
* nop .set_page_dirty method so that people can use .page_mkwrite on
|
|
* anon inodes.
|
|
*/
|
|
static int anon_set_page_dirty(struct page *page)
|
|
{
|
|
return 0;
|
|
};
|
|
|
|
/*
|
|
* A single inode exists for all anon_inode files. Contrary to pipes,
|
|
* anon_inode inodes have no associated per-instance data, so we need
|
|
* only allocate one of them.
|
|
*/
|
|
struct inode *alloc_anon_inode(struct super_block *s)
|
|
{
|
|
static const struct address_space_operations anon_aops = {
|
|
.set_page_dirty = anon_set_page_dirty,
|
|
};
|
|
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;
|
|
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(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, long arg, struct file_lock **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(const struct path *path, struct kstat *stat,
|
|
u32 request_mask, unsigned int query_flags)
|
|
{
|
|
struct inode *inode = d_inode(path->dentry);
|
|
generic_fillattr(inode, stat);
|
|
return 0;
|
|
}
|
|
|
|
static int empty_dir_setattr(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);
|
|
}
|