KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 190 insertions, 0 deletions

diff --git a/fs/smb/client/smb1misc.c b/fs/smb/client/smb1misc.c
new file mode 100644
index 000000000..cdfbbff24
--- /dev/null
+++ b/fs/smb/client/smb1misc.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ *
+ *   Copyright (C) International Business Machines  Corp., 2002,2008
+ *   Author(s): Steve French (sfrench@us.ibm.com)
+ *
+ */
+
+#include "smb1proto.h"
+#include "smberr.h"
+#include "nterr.h"
+#include "cifs_debug.h"
+
+/* NB: MID can not be set if treeCon not passed in, in that
+   case it is responsibility of caller to set the mid */
+unsigned int
+header_assemble(struct smb_hdr *buffer, char smb_command,
+		const struct cifs_tcon *treeCon, int word_count
+		/* length of fixed section (word count) in two byte units  */)
+{
+	unsigned int in_len;
+	char *temp = (char *) buffer;
+
+	memset(temp, 0, 256); /* bigger than MAX_CIFS_HDR_SIZE */
+
+	in_len = (2 * word_count) + sizeof(struct smb_hdr) +
+		2 /* for bcc field itself */;
+
+	buffer->Protocol[0] = 0xFF;
+	buffer->Protocol[1] = 'S';
+	buffer->Protocol[2] = 'M';
+	buffer->Protocol[3] = 'B';
+	buffer->Command = smb_command;
+	buffer->Flags = 0x00;	/* case sensitive */
+	buffer->Flags2 = SMBFLG2_KNOWS_LONG_NAMES;
+	buffer->Pid = cpu_to_le16((__u16)current->tgid);
+	buffer->PidHigh = cpu_to_le16((__u16)(current->tgid >> 16));
+	if (treeCon) {
+		buffer->Tid = treeCon->tid;
+		if (treeCon->ses) {
+			if (treeCon->ses->capabilities & CAP_UNICODE)
+				buffer->Flags2 |= SMBFLG2_UNICODE;
+			if (treeCon->ses->capabilities & CAP_STATUS32)
+				buffer->Flags2 |= SMBFLG2_ERR_STATUS;
+
+			/* Uid is not converted */
+			buffer->Uid = treeCon->ses->Suid;
+			if (treeCon->ses->server)
+				buffer->Mid = get_next_mid(treeCon->ses->server);
+		}
+		if (treeCon->Flags & SMB_SHARE_IS_IN_DFS)
+			buffer->Flags2 |= SMBFLG2_DFS;
+		if (treeCon->nocase)
+			buffer->Flags  |= SMBFLG_CASELESS;
+		if ((treeCon->ses) && (treeCon->ses->server))
+			if (treeCon->ses->server->sign)
+				buffer->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
+	}
+
+/*  endian conversion of flags is now done just before sending */
+	buffer->WordCount = (char) word_count;
+	return in_len;
+}
+
+bool
+is_valid_oplock_break(char *buffer, struct TCP_Server_Info *srv)
+{
+	struct smb_hdr *buf = (struct smb_hdr *)buffer;
+	struct smb_com_lock_req *pSMB = (struct smb_com_lock_req *)buf;
+	struct TCP_Server_Info *pserver;
+	struct cifs_ses *ses;
+	struct cifs_tcon *tcon;
+	struct cifsInodeInfo *pCifsInode;
+	struct cifsFileInfo *netfile;
+
+	cifs_dbg(FYI, "Checking for oplock break or dnotify response\n");
+	if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
+	   (pSMB->hdr.Flags & SMBFLG_RESPONSE)) {
+		struct smb_com_transaction_change_notify_rsp *pSMBr =
+			(struct smb_com_transaction_change_notify_rsp *)buf;
+		struct file_notify_information *pnotify;
+		__u32 data_offset = 0;
+		/* total_read excludes the RFC1002 preamble */
+		size_t len = srv->total_read;
+
+		if (get_bcc(buf) > sizeof(struct file_notify_information)) {
+			data_offset = le32_to_cpu(pSMBr->DataOffset);
+
+			if (data_offset >
+			    len - sizeof(struct file_notify_information)) {
+				cifs_dbg(FYI, "Invalid data_offset %u\n",
+					 data_offset);
+				return true;
+			}
+			pnotify = (struct file_notify_information *)
+				((char *)&pSMBr->hdr.Protocol + data_offset);
+			cifs_dbg(FYI, "dnotify on %s Action: 0x%x\n",
+				 pnotify->FileName, pnotify->Action);
+			/*   cifs_dump_mem("Rcvd notify Data: ",buf,
+				sizeof(struct smb_hdr)+60); */
+			return true;
+		}
+		if (pSMBr->hdr.Status.CifsError) {
+			cifs_dbg(FYI, "notify err 0x%x\n",
+				 pSMBr->hdr.Status.CifsError);
+			return true;
+		}
+		return false;
+	}
+	if (pSMB->hdr.Command != SMB_COM_LOCKING_ANDX)
+		return false;
+	if (pSMB->hdr.Flags & SMBFLG_RESPONSE) {
+		/* no sense logging error on invalid handle on oplock
+		   break - harmless race between close request and oplock
+		   break response is expected from time to time writing out
+		   large dirty files cached on the client */
+		if ((NT_STATUS_INVALID_HANDLE) ==
+		   le32_to_cpu(pSMB->hdr.Status.CifsError)) {
+			cifs_dbg(FYI, "Invalid handle on oplock break\n");
+			return true;
+		} else if (ERRbadfid ==
+		   le16_to_cpu(pSMB->hdr.Status.DosError.Error)) {
+			return true;
+		} else {
+			return false; /* on valid oplock brk we get "request" */
+		}
+	}
+	if (pSMB->hdr.WordCount != 8)
+		return false;
+
+	cifs_dbg(FYI, "oplock type 0x%x level 0x%x\n",
+		 pSMB->LockType, pSMB->OplockLevel);
+	if (!(pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE))
+		return false;
+
+	/* If server is a channel, select the primary channel */
+	pserver = SERVER_IS_CHAN(srv) ? srv->primary_server : srv;
+
+	/* look up tcon based on tid & uid */
+	spin_lock(&cifs_tcp_ses_lock);
+	list_for_each_entry(ses, &pserver->smb_ses_list, smb_ses_list) {
+		if (cifs_ses_exiting(ses))
+			continue;
+		list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
+			if (tcon->tid != buf->Tid)
+				continue;
+
+			cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
+			spin_lock(&tcon->open_file_lock);
+			list_for_each_entry(netfile, &tcon->openFileList, tlist) {
+				if (pSMB->Fid != netfile->fid.netfid)
+					continue;
+
+				cifs_dbg(FYI, "file id match, oplock break\n");
+				pCifsInode = CIFS_I(d_inode(netfile->dentry));
+
+				set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
+					&pCifsInode->flags);
+
+				netfile->oplock_epoch = 0;
+				netfile->oplock_level = pSMB->OplockLevel;
+				netfile->oplock_break_cancelled = false;
+				cifs_queue_oplock_break(netfile);
+
+				spin_unlock(&tcon->open_file_lock);
+				spin_unlock(&cifs_tcp_ses_lock);
+				return true;
+			}
+			spin_unlock(&tcon->open_file_lock);
+			spin_unlock(&cifs_tcp_ses_lock);
+			cifs_dbg(FYI, "No matching file for oplock break\n");
+			return true;
+		}
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
+	cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
+	return true;
+}
+
+/*
+ * calculate the size of the SMB message based on the fixed header
+ * portion, the number of word parameters and the data portion of the message
+ */
+unsigned int
+smbCalcSize(void *buf)
+{
+	struct smb_hdr *ptr = buf;
+	return (sizeof(struct smb_hdr) + (2 * ptr->WordCount) +
+		2 /* size of the bcc field */ + get_bcc(ptr));
+}