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c9d8f5f069
This continues previous patch and introduces the same protection for nlookup field. Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
570 lines
13 KiB
C
570 lines
13 KiB
C
/*
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FUSE: Filesystem in Userspace
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Copyright (C) 2001-2018 Miklos Szeredi <miklos@szeredi.hu>
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This program can be distributed under the terms of the GNU GPL.
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See the file COPYING.
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*/
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#include "fuse_i.h"
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#include <linux/iversion.h>
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#include <linux/posix_acl.h>
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#include <linux/pagemap.h>
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#include <linux/highmem.h>
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static bool fuse_use_readdirplus(struct inode *dir, struct dir_context *ctx)
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{
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struct fuse_conn *fc = get_fuse_conn(dir);
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struct fuse_inode *fi = get_fuse_inode(dir);
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if (!fc->do_readdirplus)
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return false;
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if (!fc->readdirplus_auto)
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return true;
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if (test_and_clear_bit(FUSE_I_ADVISE_RDPLUS, &fi->state))
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return true;
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if (ctx->pos == 0)
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return true;
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return false;
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}
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static void fuse_add_dirent_to_cache(struct file *file,
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struct fuse_dirent *dirent, loff_t pos)
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{
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struct fuse_inode *fi = get_fuse_inode(file_inode(file));
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size_t reclen = FUSE_DIRENT_SIZE(dirent);
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pgoff_t index;
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struct page *page;
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loff_t size;
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u64 version;
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unsigned int offset;
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void *addr;
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spin_lock(&fi->rdc.lock);
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/*
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* Is cache already completed? Or this entry does not go at the end of
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* cache?
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*/
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if (fi->rdc.cached || pos != fi->rdc.pos) {
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spin_unlock(&fi->rdc.lock);
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return;
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}
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version = fi->rdc.version;
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size = fi->rdc.size;
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offset = size & ~PAGE_MASK;
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index = size >> PAGE_SHIFT;
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/* Dirent doesn't fit in current page? Jump to next page. */
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if (offset + reclen > PAGE_SIZE) {
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index++;
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offset = 0;
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}
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spin_unlock(&fi->rdc.lock);
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if (offset) {
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page = find_lock_page(file->f_mapping, index);
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} else {
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page = find_or_create_page(file->f_mapping, index,
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mapping_gfp_mask(file->f_mapping));
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}
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if (!page)
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return;
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spin_lock(&fi->rdc.lock);
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/* Raced with another readdir */
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if (fi->rdc.version != version || fi->rdc.size != size ||
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WARN_ON(fi->rdc.pos != pos))
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goto unlock;
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addr = kmap_atomic(page);
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if (!offset)
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clear_page(addr);
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memcpy(addr + offset, dirent, reclen);
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kunmap_atomic(addr);
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fi->rdc.size = (index << PAGE_SHIFT) + offset + reclen;
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fi->rdc.pos = dirent->off;
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unlock:
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spin_unlock(&fi->rdc.lock);
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unlock_page(page);
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put_page(page);
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}
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static void fuse_readdir_cache_end(struct file *file, loff_t pos)
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{
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struct fuse_inode *fi = get_fuse_inode(file_inode(file));
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loff_t end;
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spin_lock(&fi->rdc.lock);
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/* does cache end position match current position? */
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if (fi->rdc.pos != pos) {
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spin_unlock(&fi->rdc.lock);
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return;
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}
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fi->rdc.cached = true;
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end = ALIGN(fi->rdc.size, PAGE_SIZE);
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spin_unlock(&fi->rdc.lock);
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/* truncate unused tail of cache */
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truncate_inode_pages(file->f_mapping, end);
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}
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static bool fuse_emit(struct file *file, struct dir_context *ctx,
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struct fuse_dirent *dirent)
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{
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struct fuse_file *ff = file->private_data;
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if (ff->open_flags & FOPEN_CACHE_DIR)
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fuse_add_dirent_to_cache(file, dirent, ctx->pos);
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return dir_emit(ctx, dirent->name, dirent->namelen, dirent->ino,
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dirent->type);
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}
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static int parse_dirfile(char *buf, size_t nbytes, struct file *file,
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struct dir_context *ctx)
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{
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while (nbytes >= FUSE_NAME_OFFSET) {
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struct fuse_dirent *dirent = (struct fuse_dirent *) buf;
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size_t reclen = FUSE_DIRENT_SIZE(dirent);
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if (!dirent->namelen || dirent->namelen > FUSE_NAME_MAX)
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return -EIO;
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if (reclen > nbytes)
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break;
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if (memchr(dirent->name, '/', dirent->namelen) != NULL)
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return -EIO;
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if (!fuse_emit(file, ctx, dirent))
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break;
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buf += reclen;
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nbytes -= reclen;
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ctx->pos = dirent->off;
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}
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return 0;
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}
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static int fuse_direntplus_link(struct file *file,
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struct fuse_direntplus *direntplus,
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u64 attr_version)
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{
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struct fuse_entry_out *o = &direntplus->entry_out;
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struct fuse_dirent *dirent = &direntplus->dirent;
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struct dentry *parent = file->f_path.dentry;
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struct qstr name = QSTR_INIT(dirent->name, dirent->namelen);
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struct dentry *dentry;
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struct dentry *alias;
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struct inode *dir = d_inode(parent);
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struct fuse_conn *fc;
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struct inode *inode;
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DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
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if (!o->nodeid) {
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/*
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* Unlike in the case of fuse_lookup, zero nodeid does not mean
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* ENOENT. Instead, it only means the userspace filesystem did
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* not want to return attributes/handle for this entry.
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*
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* So do nothing.
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*/
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return 0;
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}
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if (name.name[0] == '.') {
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/*
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* We could potentially refresh the attributes of the directory
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* and its parent?
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*/
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if (name.len == 1)
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return 0;
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if (name.name[1] == '.' && name.len == 2)
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return 0;
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}
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if (invalid_nodeid(o->nodeid))
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return -EIO;
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if (!fuse_valid_type(o->attr.mode))
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return -EIO;
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fc = get_fuse_conn(dir);
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name.hash = full_name_hash(parent, name.name, name.len);
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dentry = d_lookup(parent, &name);
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if (!dentry) {
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retry:
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dentry = d_alloc_parallel(parent, &name, &wq);
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if (IS_ERR(dentry))
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return PTR_ERR(dentry);
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}
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if (!d_in_lookup(dentry)) {
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struct fuse_inode *fi;
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inode = d_inode(dentry);
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if (!inode ||
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get_node_id(inode) != o->nodeid ||
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((o->attr.mode ^ inode->i_mode) & S_IFMT)) {
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d_invalidate(dentry);
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dput(dentry);
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goto retry;
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}
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if (is_bad_inode(inode)) {
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dput(dentry);
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return -EIO;
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}
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fi = get_fuse_inode(inode);
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spin_lock(&fi->lock);
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fi->nlookup++;
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spin_unlock(&fi->lock);
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forget_all_cached_acls(inode);
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fuse_change_attributes(inode, &o->attr,
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entry_attr_timeout(o),
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attr_version);
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/*
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* The other branch comes via fuse_iget()
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* which bumps nlookup inside
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*/
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} else {
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inode = fuse_iget(dir->i_sb, o->nodeid, o->generation,
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&o->attr, entry_attr_timeout(o),
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attr_version);
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if (!inode)
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inode = ERR_PTR(-ENOMEM);
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alias = d_splice_alias(inode, dentry);
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d_lookup_done(dentry);
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if (alias) {
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dput(dentry);
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dentry = alias;
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}
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if (IS_ERR(dentry))
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return PTR_ERR(dentry);
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}
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if (fc->readdirplus_auto)
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set_bit(FUSE_I_INIT_RDPLUS, &get_fuse_inode(inode)->state);
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fuse_change_entry_timeout(dentry, o);
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dput(dentry);
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return 0;
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}
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static int parse_dirplusfile(char *buf, size_t nbytes, struct file *file,
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struct dir_context *ctx, u64 attr_version)
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{
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struct fuse_direntplus *direntplus;
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struct fuse_dirent *dirent;
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size_t reclen;
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int over = 0;
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int ret;
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while (nbytes >= FUSE_NAME_OFFSET_DIRENTPLUS) {
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direntplus = (struct fuse_direntplus *) buf;
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dirent = &direntplus->dirent;
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reclen = FUSE_DIRENTPLUS_SIZE(direntplus);
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if (!dirent->namelen || dirent->namelen > FUSE_NAME_MAX)
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return -EIO;
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if (reclen > nbytes)
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break;
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if (memchr(dirent->name, '/', dirent->namelen) != NULL)
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return -EIO;
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if (!over) {
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/* We fill entries into dstbuf only as much as
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it can hold. But we still continue iterating
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over remaining entries to link them. If not,
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we need to send a FORGET for each of those
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which we did not link.
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*/
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over = !fuse_emit(file, ctx, dirent);
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if (!over)
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ctx->pos = dirent->off;
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}
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buf += reclen;
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nbytes -= reclen;
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ret = fuse_direntplus_link(file, direntplus, attr_version);
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if (ret)
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fuse_force_forget(file, direntplus->entry_out.nodeid);
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}
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return 0;
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}
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static int fuse_readdir_uncached(struct file *file, struct dir_context *ctx)
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{
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int plus, err;
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size_t nbytes;
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struct page *page;
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struct inode *inode = file_inode(file);
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struct fuse_conn *fc = get_fuse_conn(inode);
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struct fuse_req *req;
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u64 attr_version = 0;
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bool locked;
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req = fuse_get_req(fc, 1);
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if (IS_ERR(req))
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return PTR_ERR(req);
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page = alloc_page(GFP_KERNEL);
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if (!page) {
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fuse_put_request(fc, req);
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return -ENOMEM;
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}
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plus = fuse_use_readdirplus(inode, ctx);
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req->out.argpages = 1;
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req->num_pages = 1;
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req->pages[0] = page;
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req->page_descs[0].length = PAGE_SIZE;
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if (plus) {
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attr_version = fuse_get_attr_version(fc);
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fuse_read_fill(req, file, ctx->pos, PAGE_SIZE,
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FUSE_READDIRPLUS);
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} else {
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fuse_read_fill(req, file, ctx->pos, PAGE_SIZE,
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FUSE_READDIR);
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}
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locked = fuse_lock_inode(inode);
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fuse_request_send(fc, req);
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fuse_unlock_inode(inode, locked);
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nbytes = req->out.args[0].size;
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err = req->out.h.error;
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fuse_put_request(fc, req);
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if (!err) {
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if (!nbytes) {
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struct fuse_file *ff = file->private_data;
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if (ff->open_flags & FOPEN_CACHE_DIR)
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fuse_readdir_cache_end(file, ctx->pos);
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} else if (plus) {
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err = parse_dirplusfile(page_address(page), nbytes,
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file, ctx, attr_version);
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} else {
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err = parse_dirfile(page_address(page), nbytes, file,
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ctx);
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}
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}
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__free_page(page);
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fuse_invalidate_atime(inode);
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return err;
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}
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enum fuse_parse_result {
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FOUND_ERR = -1,
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FOUND_NONE = 0,
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FOUND_SOME,
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FOUND_ALL,
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};
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static enum fuse_parse_result fuse_parse_cache(struct fuse_file *ff,
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void *addr, unsigned int size,
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struct dir_context *ctx)
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{
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unsigned int offset = ff->readdir.cache_off & ~PAGE_MASK;
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enum fuse_parse_result res = FOUND_NONE;
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WARN_ON(offset >= size);
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for (;;) {
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struct fuse_dirent *dirent = addr + offset;
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unsigned int nbytes = size - offset;
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size_t reclen = FUSE_DIRENT_SIZE(dirent);
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if (nbytes < FUSE_NAME_OFFSET || !dirent->namelen)
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break;
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if (WARN_ON(dirent->namelen > FUSE_NAME_MAX))
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return FOUND_ERR;
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if (WARN_ON(reclen > nbytes))
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return FOUND_ERR;
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if (WARN_ON(memchr(dirent->name, '/', dirent->namelen) != NULL))
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return FOUND_ERR;
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if (ff->readdir.pos == ctx->pos) {
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res = FOUND_SOME;
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if (!dir_emit(ctx, dirent->name, dirent->namelen,
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dirent->ino, dirent->type))
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return FOUND_ALL;
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ctx->pos = dirent->off;
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}
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ff->readdir.pos = dirent->off;
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ff->readdir.cache_off += reclen;
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offset += reclen;
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}
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return res;
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}
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static void fuse_rdc_reset(struct inode *inode)
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{
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struct fuse_inode *fi = get_fuse_inode(inode);
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fi->rdc.cached = false;
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fi->rdc.version++;
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fi->rdc.size = 0;
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fi->rdc.pos = 0;
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}
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#define UNCACHED 1
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static int fuse_readdir_cached(struct file *file, struct dir_context *ctx)
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{
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struct fuse_file *ff = file->private_data;
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struct inode *inode = file_inode(file);
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struct fuse_conn *fc = get_fuse_conn(inode);
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struct fuse_inode *fi = get_fuse_inode(inode);
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enum fuse_parse_result res;
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pgoff_t index;
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unsigned int size;
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struct page *page;
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void *addr;
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/* Seeked? If so, reset the cache stream */
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if (ff->readdir.pos != ctx->pos) {
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ff->readdir.pos = 0;
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ff->readdir.cache_off = 0;
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}
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/*
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* We're just about to start reading into the cache or reading the
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* cache; both cases require an up-to-date mtime value.
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*/
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if (!ctx->pos && fc->auto_inval_data) {
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int err = fuse_update_attributes(inode, file);
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if (err)
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return err;
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}
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retry:
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spin_lock(&fi->rdc.lock);
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retry_locked:
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if (!fi->rdc.cached) {
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/* Starting cache? Set cache mtime. */
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if (!ctx->pos && !fi->rdc.size) {
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fi->rdc.mtime = inode->i_mtime;
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fi->rdc.iversion = inode_query_iversion(inode);
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}
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spin_unlock(&fi->rdc.lock);
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return UNCACHED;
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}
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/*
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* When at the beginning of the directory (i.e. just after opendir(3) or
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* rewinddir(3)), then need to check whether directory contents have
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* changed, and reset the cache if so.
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*/
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if (!ctx->pos) {
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if (inode_peek_iversion(inode) != fi->rdc.iversion ||
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!timespec64_equal(&fi->rdc.mtime, &inode->i_mtime)) {
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fuse_rdc_reset(inode);
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goto retry_locked;
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}
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}
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/*
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* If cache version changed since the last getdents() call, then reset
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* the cache stream.
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*/
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if (ff->readdir.version != fi->rdc.version) {
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ff->readdir.pos = 0;
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ff->readdir.cache_off = 0;
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}
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/*
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* If at the beginning of the cache, than reset version to
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* current.
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*/
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if (ff->readdir.pos == 0)
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ff->readdir.version = fi->rdc.version;
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WARN_ON(fi->rdc.size < ff->readdir.cache_off);
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index = ff->readdir.cache_off >> PAGE_SHIFT;
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if (index == (fi->rdc.size >> PAGE_SHIFT))
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size = fi->rdc.size & ~PAGE_MASK;
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else
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size = PAGE_SIZE;
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spin_unlock(&fi->rdc.lock);
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/* EOF? */
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if ((ff->readdir.cache_off & ~PAGE_MASK) == size)
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return 0;
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page = find_get_page_flags(file->f_mapping, index,
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FGP_ACCESSED | FGP_LOCK);
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spin_lock(&fi->rdc.lock);
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if (!page) {
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/*
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* Uh-oh: page gone missing, cache is useless
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*/
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if (fi->rdc.version == ff->readdir.version)
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fuse_rdc_reset(inode);
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goto retry_locked;
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}
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/* Make sure it's still the same version after getting the page. */
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if (ff->readdir.version != fi->rdc.version) {
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spin_unlock(&fi->rdc.lock);
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unlock_page(page);
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put_page(page);
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goto retry;
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}
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spin_unlock(&fi->rdc.lock);
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/*
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* Contents of the page are now protected against changing by holding
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* the page lock.
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*/
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addr = kmap(page);
|
|
res = fuse_parse_cache(ff, addr, size, ctx);
|
|
kunmap(page);
|
|
unlock_page(page);
|
|
put_page(page);
|
|
|
|
if (res == FOUND_ERR)
|
|
return -EIO;
|
|
|
|
if (res == FOUND_ALL)
|
|
return 0;
|
|
|
|
if (size == PAGE_SIZE) {
|
|
/* We hit end of page: skip to next page. */
|
|
ff->readdir.cache_off = ALIGN(ff->readdir.cache_off, PAGE_SIZE);
|
|
goto retry;
|
|
}
|
|
|
|
/*
|
|
* End of cache reached. If found position, then we are done, otherwise
|
|
* need to fall back to uncached, since the position we were looking for
|
|
* wasn't in the cache.
|
|
*/
|
|
return res == FOUND_SOME ? 0 : UNCACHED;
|
|
}
|
|
|
|
int fuse_readdir(struct file *file, struct dir_context *ctx)
|
|
{
|
|
struct fuse_file *ff = file->private_data;
|
|
struct inode *inode = file_inode(file);
|
|
int err;
|
|
|
|
if (is_bad_inode(inode))
|
|
return -EIO;
|
|
|
|
mutex_lock(&ff->readdir.lock);
|
|
|
|
err = UNCACHED;
|
|
if (ff->open_flags & FOPEN_CACHE_DIR)
|
|
err = fuse_readdir_cached(file, ctx);
|
|
if (err == UNCACHED)
|
|
err = fuse_readdir_uncached(file, ctx);
|
|
|
|
mutex_unlock(&ff->readdir.lock);
|
|
|
|
return err;
|
|
}
|