1 files changed, 362 insertions, 0 deletions

diff --git a/fs/cifs/cached_dir.c b/fs/cifs/cached_dir.c
new file mode 100644
index 000000000000..753b850b6f87
--- /dev/null
+++ b/fs/cifs/cached_dir.c
@@ -0,0 +1,362 @@
+// 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,
+		struct cached_fid **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;
+
+	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;
+
+	mutex_lock(&tcon->cfid.fid_mutex);
+	if (tcon->cfid.is_valid) {
+		cifs_dbg(FYI, "found a cached root file handle\n");
+		*cfid = &tcon->cfid;
+		kref_get(&tcon->cfid.refcount);
+		mutex_unlock(&tcon->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(&tcon->cfid.fid_mutex);
+
+	if (smb3_encryption_required(tcon))
+		flags |= CIFS_TRANSFORM_REQ;
+
+	if (!server->ops->new_lease_key)
+		return -EIO;
+
+	pfid = tcon->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(&tcon->cfid.fid_mutex);
+
+	/*
+	 * Now we need to check again as the cached root might have
+	 * been successfully re-opened from a concurrent process
+	 */
+
+	if (tcon->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(&tcon->cfid.refcount);
+
+		mutex_unlock(&tcon->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 */
+
+	tcon->cfid.tcon = tcon;
+	tcon->cfid.is_valid = true;
+	tcon->cfid.dentry = dentry;
+	dget(dentry);
+	kref_init(&tcon->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(&tcon->cfid.refcount);
+		tcon->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 *)&tcon->cfid.file_all_info))
+		tcon->cfid.file_all_info_is_valid = true;
+	tcon->cfid.time = jiffies;
+
+
+oshr_exit:
+	mutex_unlock(&tcon->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)
+		*cfid = &tcon->cfid;
+
+	return rc;
+}
+
+int open_cached_dir_by_dentry(struct cifs_tcon *tcon,
+			      struct dentry *dentry,
+			      struct cached_fid **cfid)
+{
+	mutex_lock(&tcon->cfid.fid_mutex);
+	if (tcon->cfid.dentry == dentry) {
+		cifs_dbg(FYI, "found a cached root file handle by dentry\n");
+		*cfid = &tcon->cfid;
+		kref_get(&tcon->cfid.refcount);
+		mutex_unlock(&tcon->cfid.fid_mutex);
+		return 0;
+	}
+	mutex_unlock(&tcon->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;
+}