path: root/fs/smb/client/cached_dir.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  Functions to handle the cached directory entries
 *
 *  Copyright (c) 2022, Ronnie Sahlberg <lsahlber@redhat.com>
 */

#include <linux/namei.h>
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "smb2proto.h"
#include "cached_dir.h"

static struct cached_fid *init_cached_dir(const char *path);
static void free_cached_dir(struct cached_fid *cfid);
static void smb2_close_cached_fid(struct kref *ref);
static void cfids_laundromat_worker(struct work_struct *work);
static void close_cached_dir_locked(struct cached_fid *cfid);

struct cached_dir_dentry {
	struct list_head entry;
	struct dentry *dentry;
};

static struct cached_fid *find_or_create_cached_dir(struct cached_fids *cfids,
						    const char *path,
						    bool lookup_only,
						    __u32 max_cached_dirs)
{
	struct cached_fid *cfid;

	list_for_each_entry(cfid, &cfids->entries, entry) {
		if (!strcmp(cfid->path, path)) {
			/*
			 * If it doesn't have a lease it is either not yet
			 * fully cached or it may be in the process of
			 * being deleted due to a lease break.
			 */
			if (!is_valid_cached_dir(cfid))
				return NULL;
			kref_get(&cfid->refcount);
			return cfid;
		}
	}
	if (lookup_only) {
		return NULL;
	}
	if (cfids->num_entries >= max_cached_dirs) {
		return NULL;
	}
	cfid = init_cached_dir(path);
	if (cfid == NULL) {
		return NULL;
	}
	cfid->cfids = cfids;
	cfids->num_entries++;
	list_add(&cfid->entry, &cfids->entries);
	cfid->on_list = true;
	kref_get(&cfid->refcount);
	/*
	 * Set @cfid->has_lease to true during construction so that the lease
	 * reference can be put in cached_dir_lease_break() due to a potential
	 * lease break right after the request is sent or while @cfid is still
	 * being cached, or if a reconnection is triggered during construction.
	 * Concurrent processes won't be to use it yet due to @cfid->time being
	 * zero.
	 */
	cfid->has_lease = true;

	return cfid;
}

static struct dentry *
path_to_dentry(struct cifs_sb_info *cifs_sb, const char *path)
{
	struct dentry *dentry;
	const char *s, *p;
	char sep;

	sep = CIFS_DIR_SEP(cifs_sb);
	dentry = dget(cifs_sb->root);
	s = path;

	do {
		struct inode *dir = d_inode(dentry);
		struct dentry *child;

		if (!S_ISDIR(dir->i_mode)) {
			dput(dentry);
			dentry = ERR_PTR(-ENOTDIR);
			break;
		}

		/* skip separators */
		while (*s == sep)
			s++;
		if (!*s)
			break;
		p = s++;
		/* next separator */
		while (*s && *s != sep)
			s++;

		child = lookup_noperm_positive_unlocked(&QSTR_LEN(p, s - p),
							dentry);
		dput(dentry);
		dentry = child;
	} while (!IS_ERR(dentry));
	return dentry;
}

static const char *path_no_prefix(struct cifs_sb_info *cifs_sb,
				  const char *path)
{
	size_t len = 0;

	if (!*path)
		return path;

	if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH) &&
	    cifs_sb->prepath) {
		len = strlen(cifs_sb->prepath) + 1;
		if (unlikely(len > strlen(path)))
			return ERR_PTR(-EINVAL);
	}
	return path + len;
}

/*
 * Open the and cache a directory handle.
 * If error then *cfid is not initialized.
 */
int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
		    const char *path,
		    struct cifs_sb_info *cifs_sb,
		    bool lookup_only, struct cached_fid **ret_cfid)
{
	struct cifs_ses *ses;
	struct TCP_Server_Info *server;
	struct cifs_open_parms oparms;
	struct smb2_create_rsp *o_rsp = NULL;
	struct smb2_query_info_rsp *qi_rsp = NULL;
	int resp_buftype[2];
	struct smb_rqst rqst[2];
	struct kvec rsp_iov[2];
	struct kvec open_iov[SMB2_CREATE_IOV_SIZE];
	struct kvec qi_iov[1];
	int rc, flags = 0;
	__le16 *utf16_path = NULL;
	u8 oplock = SMB2_OPLOCK_LEVEL_II;
	struct cifs_fid *pfid;
	struct dentry *dentry = NULL;
	struct cached_fid *cfid;
	struct cached_fids *cfids;
	const char *npath;
	int retries = 0, cur_sleep = 1;
	__le32 lease_flags = 0;

	if (cifs_sb->root == NULL)
		return -ENOENT;

	if (tcon == NULL)
		return