--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Functions to handle the cached directory entries
+ *
+ * Copyright (c) 2022, Ronnie Sahlberg <lsahlber@redhat.com>
+ */
+
+#include "cifsglob.h"
+#include "cifsproto.h"
+#include "cifs_debug.h"
+#include "smb2proto.h"
+#include "cached_dir.h"
+
+/*
+ * 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 = 0; /* Null - since an open of top of share */
+ u8 oplock = SMB2_OPLOCK_LEVEL_II;
+ struct cifs_fid *pfid;
+ struct dentry *dentry;
+ struct cached_fid *cfid;
+
+ if (tcon == NULL || tcon->nohandlecache ||
+ is_smb1_server(tcon->ses->server))
+ return -EOPNOTSUPP;
+
+ ses = tcon->ses;
+ server = ses->server;
+
+ if (cifs_sb->root == NULL)
+ return -ENOENT;
+
+ if (strlen(path))
+ return -ENOENT;
+
+ dentry = cifs_sb->root;
+
+ cfid = tcon->cfid;
+ mutex_lock(&cfid->fid_mutex);
+ if (cfid->is_valid) {
+ cifs_dbg(FYI, "found a cached root file handle\n");
+ *ret_cfid = cfid;
+ kref_get(&cfid->refcount);
+ mutex_unlock(&cfid->fid_mutex);
+ return 0;
+ }
+
+ /*
+ * We do not hold the lock for the open because in case
+ * SMB2_open needs to reconnect, it will end up calling
+ * cifs_mark_open_files_invalid() which takes the lock again
+ * thus causing a deadlock
+ */
+ mutex_unlock(&cfid->fid_mutex);
+
+ if (lookup_only)
+ return -ENOENT;
+
+ if (smb3_encryption_required(tcon))
+ flags |= CIFS_TRANSFORM_REQ;
+
+ if (!server->ops->new_lease_key)
+ return -EIO;
+
+ pfid = &cfid->fid;
+ server->ops->new_lease_key(pfid);
+
+ memset(rqst, 0, sizeof(rqst));
+ resp_buftype[0] = resp_buftype[1] = CIFS_NO_BUFFER;
+ memset(rsp_iov, 0, sizeof(rsp_iov));
+
+ /* Open */
+ memset(&open_iov, 0, sizeof(open_iov));
+ rqst[0].rq_iov = open_iov;
+ rqst[0].rq_nvec = SMB2_CREATE_IOV_SIZE;
+
+ oparms.tcon = tcon;
+ oparms.create_options = cifs_create_options(cifs_sb, CREATE_NOT_FILE);
+ oparms.desired_access = FILE_READ_ATTRIBUTES;
+ oparms.disposition = FILE_OPEN;
+ oparms.fid = pfid;
+ oparms.reconnect = false;
+
+ rc = SMB2_open_init(tcon, server,
+ &rqst[0], &oplock, &oparms, &utf16_path);
+ if (rc)
+ goto oshr_free;
+ smb2_set_next_command(tcon, &rqst[0]);
+
+ memset(&qi_iov, 0, sizeof(qi_iov));
+ rqst[1].rq_iov = qi_iov;
+ rqst[1].rq_nvec = 1;
+
+ rc = SMB2_query_info_init(tcon, server,
+ &rqst[1], COMPOUND_FID,
+ COMPOUND_FID, FILE_ALL_INFORMATION,
+ SMB2_O_INFO_FILE, 0,
+ sizeof(struct smb2_file_all_info) +
+ PATH_MAX * 2, 0, NULL);
+ if (rc)
+ goto oshr_free;
+
+ smb2_set_related(&rqst[1]);
+
+ rc = compound_send_recv(xid, ses, server,
+ flags, 2, rqst,
+ resp_buftype, rsp_iov);
+ mutex_lock(&cfid->fid_mutex);
+
+ /*
+ * Now we need to check again as the cached root might have
+ * been successfully re-opened from a concurrent process
+ */
+
+ if (cfid->is_valid) {
+ /* work was already done */
+
+ /* stash fids for close() later */
+ struct cifs_fid fid = {
+ .persistent_fid = pfid->persistent_fid,
+ .volatile_fid = pfid->volatile_fid,
+ };
+
+ /*
+ * caller expects this func to set the fid in cfid to valid
+ * cached root, so increment the refcount.
+ */
+ kref_get(&cfid->refcount);
+
+ mutex_unlock(&cfid->fid_mutex);
+
+ if (rc == 0) {
+ /* close extra handle outside of crit sec */
+ SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
+ }
+ rc = 0;
+ goto oshr_free;
+ }
+
+ /* Cached root is still invalid, continue normaly */
+
+ if (rc) {
+ if (rc == -EREMCHG) {
+ tcon->need_reconnect = true;
+ pr_warn_once("server share %s deleted\n",
+ tcon->treeName);
+ }
+ goto oshr_exit;
+ }
+
+ atomic_inc(&tcon->num_remote_opens);
+
+ o_rsp = (struct smb2_create_rsp *)rsp_iov[0].iov_base;
+ oparms.fid->persistent_fid = o_rsp->PersistentFileId;
+ oparms.fid->volatile_fid = o_rsp->VolatileFileId;
+#ifdef CONFIG_CIFS_DEBUG2
+ oparms.fid->mid = le64_to_cpu(o_rsp->hdr.MessageId);
+#endif /* CIFS_DEBUG2 */
+
+ cfid->tcon = tcon;
+ cfid->is_valid = true;
+ cfid->dentry = dentry;
+ dget(dentry);
+ kref_init(&cfid->refcount);
+
+ /* BB TBD check to see if oplock level check can be removed below */
+ if (o_rsp->OplockLevel == SMB2_OPLOCK_LEVEL_LEASE) {
+ /*
+ * See commit 2f94a3125b87. Increment the refcount when we
+ * get a lease for root, release it if lease break occurs
+ */
+ kref_get(&cfid->refcount);
+ cfid->has_lease = true;
+ smb2_parse_contexts(server, o_rsp,
+ &oparms.fid->epoch,
+ oparms.fid->lease_key, &oplock,
+ NULL, NULL);
+ } else
+ goto oshr_exit;
+
+ qi_rsp = (struct smb2_query_info_rsp *)rsp_iov[1].iov_base;
+ if (le32_to_cpu(qi_rsp->OutputBufferLength) < sizeof(struct smb2_file_all_info))
+ goto oshr_exit;
+ if (!smb2_validate_and_copy_iov(
+ le16_to_cpu(qi_rsp->OutputBufferOffset),
+ sizeof(struct smb2_file_all_info),
+ &rsp_iov[1], sizeof(struct smb2_file_all_info),
+ (char *)&cfid->file_all_info))
+ cfid->file_all_info_is_valid = true;
+
+ cfid->time = jiffies;
+
+oshr_exit:
+ mutex_unlock(&cfid->fid_mutex);
+oshr_free:
+ SMB2_open_free(&rqst[0]);
+ SMB2_query_info_free(&rqst[1]);
+ free_rsp_buf(resp_buftype[0], rsp_iov[0].iov_base);
+ free_rsp_buf(resp_buftype[1], rsp_iov[1].iov_base);
+ if (rc == 0)
+ *ret_cfid = cfid;
+
+ return rc;
+}
+
+int open_cached_dir_by_dentry(struct cifs_tcon *tcon,
+ struct dentry *dentry,
+ struct cached_fid **ret_cfid)
+{
+ struct cached_fid *cfid;
+
+ cfid = tcon->cfid;
+
+ mutex_lock(&cfid->fid_mutex);
+ if (cfid->dentry == dentry) {
+ cifs_dbg(FYI, "found a cached root file handle by dentry\n");
+ *ret_cfid = cfid;
+ kref_get(&cfid->refcount);
+ mutex_unlock(&cfid->fid_mutex);
+ return 0;
+ }
+ mutex_unlock(&cfid->fid_mutex);
+ return -ENOENT;
+}
+
+static void
+smb2_close_cached_fid(struct kref *ref)
+{
+ struct cached_fid *cfid = container_of(ref, struct cached_fid,
+ refcount);
+ struct cached_dirent *dirent, *q;
+
+ if (cfid->is_valid) {
+ cifs_dbg(FYI, "clear cached root file handle\n");
+ SMB2_close(0, cfid->tcon, cfid->fid.persistent_fid,
+ cfid->fid.volatile_fid);
+ }
+
+ /*
+ * We only check validity above to send SMB2_close,
+ * but we still need to invalidate these entries
+ * when this function is called
+ */
+ cfid->is_valid = false;
+ cfid->file_all_info_is_valid = false;
+ cfid->has_lease = false;
+ if (cfid->dentry) {
+ dput(cfid->dentry);
+ cfid->dentry = NULL;
+ }
+ /*
+ * Delete all cached dirent names
+ */
+ mutex_lock(&cfid->dirents.de_mutex);
+ list_for_each_entry_safe(dirent, q, &cfid->dirents.entries, entry) {
+ list_del(&dirent->entry);
+ kfree(dirent->name);
+ kfree(dirent);
+ }
+ cfid->dirents.is_valid = 0;
+ cfid->dirents.is_failed = 0;
+ cfid->dirents.ctx = NULL;
+ cfid->dirents.pos = 0;
+ mutex_unlock(&cfid->dirents.de_mutex);
+
+}
+
+void close_cached_dir(struct cached_fid *cfid)
+{
+ mutex_lock(&cfid->fid_mutex);
+ kref_put(&cfid->refcount, smb2_close_cached_fid);
+ mutex_unlock(&cfid->fid_mutex);
+}
+
+void close_cached_dir_lease_locked(struct cached_fid *cfid)
+{
+ if (cfid->has_lease) {
+ cfid->has_lease = false;
+ kref_put(&cfid->refcount, smb2_close_cached_fid);
+ }
+}
+
+void close_cached_dir_lease(struct cached_fid *cfid)
+{
+ mutex_lock(&cfid->fid_mutex);
+ close_cached_dir_lease_locked(cfid);
+ mutex_unlock(&cfid->fid_mutex);
+}
+
+/*
+ * Called from cifs_kill_sb when we unmount a share
+ */
+void close_all_cached_dirs(struct cifs_sb_info *cifs_sb)
+{
+ struct rb_root *root = &cifs_sb->tlink_tree;
+ struct rb_node *node;
+ struct cached_fid *cfid;
+ struct cifs_tcon *tcon;
+ struct tcon_link *tlink;
+
+ for (node = rb_first(root); node; node = rb_next(node)) {
+ tlink = rb_entry(node, struct tcon_link, tl_rbnode);
+ tcon = tlink_tcon(tlink);
+ if (IS_ERR(tcon))
+ continue;
+ cfid = tcon->cfid;
+ mutex_lock(&cfid->fid_mutex);
+ if (cfid->dentry) {
+ dput(cfid->dentry);
+ cfid->dentry = NULL;
+ }
+ mutex_unlock(&cfid->fid_mutex);
+ }
+}
+
+/*
+ * Invalidate and close all cached dirs when a TCON has been reset
+ * due to a session loss.
+ */
+void invalidate_all_cached_dirs(struct cifs_tcon *tcon)
+{
+ mutex_lock(&tcon->cfid->fid_mutex);
+ tcon->cfid->is_valid = false;
+ /* cached handle is not valid, so SMB2_CLOSE won't be sent below */
+ close_cached_dir_lease_locked(tcon->cfid);
+ memset(&tcon->cfid->fid, 0, sizeof(struct cifs_fid));
+ mutex_unlock(&tcon->cfid->fid_mutex);
+}
+
+static void
+smb2_cached_lease_break(struct work_struct *work)
+{
+ struct cached_fid *cfid = container_of(work,
+ struct cached_fid, lease_break);
+
+ close_cached_dir_lease(cfid);
+}
+
+int cached_dir_lease_break(struct cifs_tcon *tcon, __u8 lease_key[16])
+{
+ if (tcon->cfid->is_valid &&
+ !memcmp(lease_key,
+ tcon->cfid->fid.lease_key,
+ SMB2_LEASE_KEY_SIZE)) {
+ tcon->cfid->time = 0;
+ INIT_WORK(&tcon->cfid->lease_break,
+ smb2_cached_lease_break);
+ queue_work(cifsiod_wq,
+ &tcon->cfid->lease_break);
+ return true;
+ }
+ return false;
+}
+
+struct cached_fid *init_cached_dir(void)
+{
+ struct cached_fid *cfid;
+
+ cfid = kzalloc(sizeof(*cfid), GFP_KERNEL);
+ if (!cfid)
+ return NULL;
+ INIT_LIST_HEAD(&cfid->dirents.entries);
+ mutex_init(&cfid->dirents.de_mutex);
+ mutex_init(&cfid->fid_mutex);
+ return cfid;
+}
+
+void free_cached_dir(struct cifs_tcon *tcon)
+{
+ kfree(tcon->cfid);
+}
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