Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1438 insertions, 0 deletions

diff --git a/fs/smb/client/misc.c b/fs/smb/client/misc.c
new file mode 100644
index 000000000..41290c12d
--- /dev/null
+++ b/fs/smb/client/misc.c
@@ -0,0 +1,1438 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ *
+ *   Copyright (C) International Business Machines  Corp., 2002,2008
+ *   Author(s): Steve French (sfrench@us.ibm.com)
+ *
+ */
+
+#include <linux/slab.h>
+#include <linux/ctype.h>
+#include <linux/mempool.h>
+#include <linux/vmalloc.h>
+#include "cifspdu.h"
+#include "cifsglob.h"
+#include "cifsproto.h"
+#include "cifs_debug.h"
+#include "smberr.h"
+#include "nterr.h"
+#include "cifs_unicode.h"
+#include "smb2pdu.h"
+#include "cifsfs.h"
+#ifdef CONFIG_CIFS_DFS_UPCALL
+#include "dns_resolve.h"
+#include "dfs_cache.h"
+#endif
+#include "fs_context.h"
+#include "cached_dir.h"
+
+extern mempool_t *cifs_sm_req_poolp;
+extern mempool_t *cifs_req_poolp;
+
+/* The xid serves as a useful identifier for each incoming vfs request,
+   in a similar way to the mid which is useful to track each sent smb,
+   and CurrentXid can also provide a running counter (although it
+   will eventually wrap past zero) of the total vfs operations handled
+   since the cifs fs was mounted */
+
+unsigned int
+_get_xid(void)
+{
+	unsigned int xid;
+
+	spin_lock(&GlobalMid_Lock);
+	GlobalTotalActiveXid++;
+
+	/* keep high water mark for number of simultaneous ops in filesystem */
+	if (GlobalTotalActiveXid > GlobalMaxActiveXid)
+		GlobalMaxActiveXid = GlobalTotalActiveXid;
+	if (GlobalTotalActiveXid > 65000)
+		cifs_dbg(FYI, "warning: more than 65000 requests active\n");
+	xid = GlobalCurrentXid++;
+	spin_unlock(&GlobalMid_Lock);
+	return xid;
+}
+
+void
+_free_xid(unsigned int xid)
+{
+	spin_lock(&GlobalMid_Lock);
+	/* if (GlobalTotalActiveXid == 0)
+		BUG(); */
+	GlobalTotalActiveXid--;
+	spin_unlock(&GlobalMid_Lock);
+}
+
+struct cifs_ses *
+sesInfoAlloc(void)
+{
+	struct cifs_ses *ret_buf;
+
+	ret_buf = kzalloc(sizeof(struct cifs_ses), GFP_KERNEL);
+	if (ret_buf) {
+		atomic_inc(&sesInfoAllocCount);
+		spin_lock_init(&ret_buf->ses_lock);
+		ret_buf->ses_status = SES_NEW;
+		++ret_buf->ses_count;
+		INIT_LIST_HEAD(&ret_buf->smb_ses_list);
+		INIT_LIST_HEAD(&ret_buf->tcon_list);
+		mutex_init(&ret_buf->session_mutex);
+		spin_lock_init(&ret_buf->iface_lock);
+		INIT_LIST_HEAD(&ret_buf->iface_list);
+		spin_lock_init(&ret_buf->chan_lock);
+	}
+	return ret_buf;
+}
+
+void
+sesInfoFree(struct cifs_ses *buf_to_free)
+{
+	struct cifs_server_iface *iface = NULL, *niface = NULL;
+
+	if (buf_to_free == NULL) {
+		cifs_dbg(FYI, "Null buffer passed to sesInfoFree\n");
+		return;
+	}
+
+	atomic_dec(&sesInfoAllocCount);
+	kfree(buf_to_free->serverOS);
+	kfree(buf_to_free->serverDomain);
+	kfree(buf_to_free->serverNOS);
+	kfree_sensitive(buf_to_free->password);
+	kfree(buf_to_free->user_name);
+	kfree(buf_to_free->domainName);
+	kfree_sensitive(buf_to_free->auth_key.response);
+	spin_lock(&buf_to_free->iface_lock);
+	list_for_each_entry_safe(iface, niface, &buf_to_free->iface_list,
+				 iface_head)
+		kref_put(&iface->refcount, release_iface);
+	spin_unlock(&buf_to_free->iface_lock);
+	kfree_sensitive(buf_to_free);
+}
+
+struct cifs_tcon *
+tconInfoAlloc(void)
+{
+	struct cifs_tcon *ret_buf;
+
+	ret_buf = kzalloc(sizeof(*ret_buf), GFP_KERNEL);
+	if (!ret_buf)
+		return NULL;
+	ret_buf->cfids = init_cached_dirs();
+	if (!ret_buf->cfids) {
+		kfree(ret_buf);
+		return NULL;
+	}
+
+	atomic_inc(&tconInfoAllocCount);
+	ret_buf->status = TID_NEW;
+	++ret_buf->tc_count;
+	spin_lock_init(&ret_buf->tc_lock);
+	INIT_LIST_HEAD(&ret_buf->openFileList);
+	INIT_LIST_HEAD(&ret_buf->tcon_list);
+	spin_lock_init(&ret_buf->open_file_lock);
+	spin_lock_init(&ret_buf->stat_lock);
+	atomic_set(&ret_buf->num_local_opens, 0);
+	atomic_set(&ret_buf->num_remote_opens, 0);
+
+	return ret_buf;
+}
+
+void
+tconInfoFree(struct cifs_tcon *tcon)
+{
+	if (tcon == NULL) {
+		cifs_dbg(FYI, "Null buffer passed to tconInfoFree\n");
+		return;
+	}
+	free_cached_dirs(tcon->cfids);
+	atomic_dec(&tconInfoAllocCount);
+	kfree(tcon->nativeFileSystem);
+	kfree_sensitive(tcon->password);
+	kfree(tcon);
+}
+
+struct smb_hdr *
+cifs_buf_get(void)
+{
+	struct smb_hdr *ret_buf = NULL;
+	/*
+	 * SMB2 header is bigger than CIFS one - no problems to clean some
+	 * more bytes for CIFS.
+	 */
+	size_t buf_size = sizeof(struct smb2_hdr);
+
+	/*
+	 * We could use negotiated size instead of max_msgsize -
+	 * but it may be more efficient to always alloc same size
+	 * albeit slightly larger than necessary and maxbuffersize
+	 * defaults to this and can not be bigger.
+	 */
+	ret_buf = mempool_alloc(cifs_req_poolp, GFP_NOFS);
+
+	/* clear the first few header bytes */
+	/* for most paths, more is cleared in header_assemble */
+	memset(ret_buf, 0, buf_size + 3);
+	atomic_inc(&buf_alloc_count);
+#ifdef CONFIG_CIFS_STATS2
+	atomic_inc(&total_buf_alloc_count);
+#endif /* CONFIG_CIFS_STATS2 */
+
+	return ret_buf;
+}
+
+void
+cifs_buf_release(void *buf_to_free)
+{
+	if (buf_to_free == NULL) {
+		/* cifs_dbg(FYI, "Null buffer passed to cifs_buf_release\n");*/
+		return;
+	}
+	mempool_free(buf_to_free, cifs_req_poolp);
+
+	atomic_dec(&buf_alloc_count);
+	return;
+}
+
+struct smb_hdr *
+cifs_small_buf_get(void)
+{
+	struct smb_hdr *ret_buf = NULL;
+
+/* We could use negotiated size instead of max_msgsize -
+   but it may be more efficient to always alloc same size
+   albeit slightly larger than necessary and maxbuffersize
+   defaults to this and can not be bigger */
+	ret_buf = mempool_alloc(cifs_sm_req_poolp, GFP_NOFS);
+	/* No need to clear memory here, cleared in header assemble */
+	/*	memset(ret_buf, 0, sizeof(struct smb_hdr) + 27);*/
+	atomic_inc(&small_buf_alloc_count);
+#ifdef CONFIG_CIFS_STATS2
+	atomic_inc(&total_small_buf_alloc_count);
+#endif /* CONFIG_CIFS_STATS2 */
+
+	return ret_buf;
+}
+
+void
+cifs_small_buf_release(void *buf_to_free)
+{
+
+	if (buf_to_free == NULL) {
+		cifs_dbg(FYI, "Null buffer passed to cifs_small_buf_release\n");
+		return;
+	}
+	mempool_free(buf_to_free, cifs_sm_req_poolp);
+
+	atomic_dec(&small_buf_alloc_count);
+	return;
+}
+
+void
+free_rsp_buf(int resp_buftype, void *rsp)
+{
+	if (resp_buftype == CIFS_SMALL_BUFFER)
+		cifs_small_buf_release(rsp);
+	else if (resp_buftype == CIFS_LARGE_BUFFER)
+		cifs_buf_release(rsp);
+}
+
+/* NB: MID can not be set if treeCon not passed in, in that
+   case it is responsbility of caller to set the mid */
+void
+header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
+		const struct cifs_tcon *treeCon, int word_count
+		/* length of fixed section (word count) in two byte units  */)
+{
+	char *temp = (char *) buffer;
+
+	memset(temp, 0, 256); /* bigger than MAX_CIFS_HDR_SIZE */
+
+	buffer->smb_buf_length = cpu_to_be32(
+	    (2 * word_count) + sizeof(struct smb_hdr) -
+	    4 /*  RFC 1001 length field does not count */  +
+	    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;
+}
+
+static int
+check_smb_hdr(struct smb_hdr *smb)
+{
+	/* does it have the right SMB "signature" ? */
+	if (*(__le32 *) smb->Protocol != cpu_to_le32(0x424d53ff)) {
+		cifs_dbg(VFS, "Bad protocol string signature header 0x%x\n",
+			 *(unsigned int *)smb->Protocol);
+		return 1;
+	}
+
+	/* if it's a response then accept */
+	if (smb->Flags & SMBFLG_RESPONSE)
+		return 0;
+
+	/* only one valid case where server sends us request */
+	if (smb->Command == SMB_COM_LOCKING_ANDX)
+		return 0;
+
+	cifs_dbg(VFS, "Server sent request, not response. mid=%u\n",
+		 get_mid(smb));
+	return 1;
+}
+
+int
+checkSMB(char *buf, unsigned int total_read, struct TCP_Server_Info *server)
+{
+	struct smb_hdr *smb = (struct smb_hdr *)buf;
+	__u32 rfclen = be32_to_cpu(smb->smb_buf_length);
+	__u32 clc_len;  /* calculated length */
+	cifs_dbg(FYI, "checkSMB Length: 0x%x, smb_buf_length: 0x%x\n",
+		 total_read, rfclen);
+
+	/* is this frame too small to even get to a BCC? */
+	if (total_read < 2 + sizeof(struct smb_hdr)) {
+		if ((total_read >= sizeof(struct smb_hdr) - 1)
+			    && (smb->Status.CifsError != 0)) {
+			/* it's an error return */
+			smb->WordCount = 0;
+			/* some error cases do not return wct and bcc */
+			return 0;
+		} else if ((total_read == sizeof(struct smb_hdr) + 1) &&
+				(smb->WordCount == 0)) {
+			char *tmp = (char *)smb;
+			/* Need to work around a bug in two servers here */
+			/* First, check if the part of bcc they sent was zero */
+			if (tmp[sizeof(struct smb_hdr)] == 0) {
+				/* some servers return only half of bcc
+				 * on simple responses (wct, bcc both zero)
+				 * in particular have seen this on
+				 * ulogoffX and FindClose. This leaves
+				 * one byte of bcc potentially unitialized
+				 */
+				/* zero rest of bcc */
+				tmp[sizeof(struct smb_hdr)+1] = 0;
+				return 0;
+			}
+			cifs_dbg(VFS, "rcvd invalid byte count (bcc)\n");
+		} else {
+			cifs_dbg(VFS, "Length less than smb header size\n");
+		}
+		return -EIO;
+	} else if (total_read < sizeof(*smb) + 2 * smb->WordCount) {
+		cifs_dbg(VFS, "%s: can't read BCC due to invalid WordCount(%u)\n",
+			 __func__, smb->WordCount);
+		return -EIO;
+	}
+
+	/* otherwise, there is enough to get to the BCC */
+	if (check_smb_hdr(smb))
+		return -EIO;
+	clc_len = smbCalcSize(smb);
+
+	if (4 + rfclen != total_read) {
+		cifs_dbg(VFS, "Length read does not match RFC1001 length %d\n",
+			 rfclen);
+		return -EIO;
+	}
+
+	if (4 + rfclen != clc_len) {
+		__u16 mid = get_mid(smb);
+		/* check if bcc wrapped around for large read responses */
+		if ((rfclen > 64 * 1024) && (rfclen > clc_len)) {
+			/* check if lengths match mod 64K */
+			if (((4 + rfclen) & 0xFFFF) == (clc_len & 0xFFFF))
+				return 0; /* bcc wrapped */
+		}
+		cifs_dbg(FYI, "Calculated size %u vs length %u mismatch for mid=%u\n",
+			 clc_len, 4 + rfclen, mid);
+
+		if (4 + rfclen < clc_len) {
+			cifs_dbg(VFS, "RFC1001 size %u smaller than SMB for mid=%u\n",
+				 rfclen, mid);
+			return -EIO;
+		} else if (rfclen > clc_len + 512) {
+			/*
+			 * Some servers (Windows XP in particular) send more
+			 * data than the lengths in the SMB packet would
+			 * indicate on certain calls (byte range locks and
+			 * trans2 find first calls in particular). While the
+			 * client can handle such a frame by ignoring the
+			 * trailing data, we choose limit the amount of extra
+			 * data to 512 bytes.
+			 */
+			cifs_dbg(VFS, "RFC1001 size %u more than 512 bytes larger than SMB for mid=%u\n",
+				 rfclen, mid);
+			return -EIO;
+		}
+	}
+	return 0;
+}
+
+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;
+		size_t len = srv->total_read - sizeof(pSMBr->hdr.smb_buf_length);
+
+		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 = CIFS_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) {
+		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;
+}
+
+void
+dump_smb(void *buf, int smb_buf_length)
+{
+	if (traceSMB == 0)
+		return;
+
+	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_NONE, 8, 2, buf,
+		       smb_buf_length, true);
+}
+
+void
+cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
+{
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
+		struct cifs_tcon *tcon = NULL;
+
+		if (cifs_sb->master_tlink)
+			tcon = cifs_sb_master_tcon(cifs_sb);
+
+		cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
+		cifs_sb->mnt_cifs_serverino_autodisabled = true;
+		cifs_dbg(VFS, "Autodisabling the use of server inode numbers on %s\n",
+			 tcon ? tcon->tree_name : "new server");
+		cifs_dbg(VFS, "The server doesn't seem to support them properly or the files might be on different servers (DFS)\n");
+		cifs_dbg(VFS, "Hardlinks will not be recognized on this mount. Consider mounting with the \"noserverino\" option to silence this message.\n");
+
+	}
+}
+
+void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
+{
+	oplock &= 0xF;
+
+	if (oplock == OPLOCK_EXCLUSIVE) {
+		cinode->oplock = CIFS_CACHE_WRITE_FLG | CIFS_CACHE_READ_FLG;
+		cifs_dbg(FYI, "Exclusive Oplock granted on inode %p\n",
+			 &cinode->netfs.inode);
+	} else if (oplock == OPLOCK_READ) {
+		cinode->oplock = CIFS_CACHE_READ_FLG;
+		cifs_dbg(FYI, "Level II Oplock granted on inode %p\n",
+			 &cinode->netfs.inode);
+	} else
+		cinode->oplock = 0;
+}
+
+/*
+ * We wait for oplock breaks to be processed before we attempt to perform
+ * writes.
+ */
+int cifs_get_writer(struct cifsInodeInfo *cinode)
+{
+	int rc;
+
+start:
+	rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK,
+			 TASK_KILLABLE);
+	if (rc)
+		return rc;
+
+	spin_lock(&cinode->writers_lock);
+	if (!cinode->writers)
+		set_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
+	cinode->writers++;
+	/* Check to see if we have started servicing an oplock break */
+	if (test_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags)) {
+		cinode->writers--;
+		if (cinode->writers == 0) {
+			clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
+			wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
+		}
+		spin_unlock(&cinode->writers_lock);
+		goto start;
+	}
+	spin_unlock(&cinode->writers_lock);
+	return 0;
+}
+
+void cifs_put_writer(struct cifsInodeInfo *cinode)
+{
+	spin_lock(&cinode->writers_lock);
+	cinode->writers--;
+	if (cinode->writers == 0) {
+		clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
+		wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
+	}
+	spin_unlock(&cinode->writers_lock);
+}
+
+/**
+ * cifs_queue_oplock_break - queue the oplock break handler for cfile
+ * @cfile: The file to break the oplock on
+ *
+ * This function is called from the demultiplex thread when it
+ * receives an oplock break for @cfile.
+ *
+ * Assumes the tcon->open_file_lock is held.
+ * Assumes cfile->file_info_lock is NOT held.
+ */
+void cifs_queue_oplock_break(struct cifsFileInfo *cfile)
+{
+	/*
+	 * Bump the handle refcount now while we hold the
+	 * open_file_lock to enforce the validity of it for the oplock
+	 * break handler. The matching put is done at the end of the
+	 * handler.
+	 */
+	cifsFileInfo_get(cfile);
+
+	queue_work(cifsoplockd_wq, &cfile->oplock_break);
+}
+
+void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
+{
+	clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
+	wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK);
+}
+
+bool
+backup_cred(struct cifs_sb_info *cifs_sb)
+{
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
+		if (uid_eq(cifs_sb->ctx->backupuid, current_fsuid()))
+			return true;
+	}
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
+		if (in_group_p(cifs_sb->ctx->backupgid))
+			return true;
+	}
+
+	return false;
+}
+
+void
+cifs_del_pending_open(struct cifs_pending_open *open)
+{
+	spin_lock(&tlink_tcon(open->tlink)->open_file_lock);
+	list_del(&open->olist);
+	spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
+}
+
+void
+cifs_add_pending_open_locked(struct cifs_fid *fid, struct tcon_link *tlink,
+			     struct cifs_pending_open *open)
+{
+	memcpy(open->lease_key, fid->lease_key, SMB2_LEASE_KEY_SIZE);
+	open->oplock = CIFS_OPLOCK_NO_CHANGE;
+	open->tlink = tlink;
+	fid->pending_open = open;
+	list_add_tail(&open->olist, &tlink_tcon(tlink)->pending_opens);
+}
+
+void
+cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
+		      struct cifs_pending_open *open)
+{
+	spin_lock(&tlink_tcon(tlink)->open_file_lock);
+	cifs_add_pending_open_locked(fid, tlink, open);
+	spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
+}
+
+/*
+ * Critical section which runs after acquiring deferred_lock.
+ * As there is no reference count on cifs_deferred_close, pdclose
+ * should not be used outside deferred_lock.
+ */
+bool
+cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **pdclose)
+{
+	struct cifs_deferred_close *dclose;
+
+	list_for_each_entry(dclose, &CIFS_I(d_inode(cfile->dentry))->deferred_closes, dlist) {
+		if ((dclose->netfid == cfile->fid.netfid) &&
+			(dclose->persistent_fid == cfile->fid.persistent_fid) &&
+			(dclose->volatile_fid == cfile->fid.volatile_fid)) {
+			*pdclose = dclose;
+			return true;
+		}
+	}
+	return false;
+}
+
+/*
+ * Critical section which runs after acquiring deferred_lock.
+ */
+void
+cifs_add_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close *dclose)
+{
+	bool is_deferred = false;
+	struct cifs_deferred_close *pdclose;
+
+	is_deferred = cifs_is_deferred_close(cfile, &pdclose);
+	if (is_deferred) {
+		kfree(dclose);
+		return;
+	}
+
+	dclose->tlink = cfile->tlink;
+	dclose->netfid = cfile->fid.netfid;
+	dclose->persistent_fid = cfile->fid.persistent_fid;
+	dclose->volatile_fid = cfile->fid.volatile_fid;
+	list_add_tail(&dclose->dlist, &CIFS_I(d_inode(cfile->dentry))->deferred_closes);
+}
+
+/*
+ * Critical section which runs after acquiring deferred_lock.
+ */
+void
+cifs_del_deferred_close(struct cifsFileInfo *cfile)
+{
+	bool is_deferred = false;
+	struct cifs_deferred_close *dclose;
+
+	is_deferred = cifs_is_deferred_close(cfile, &dclose);
+	if (!is_deferred)
+		return;
+	list_del(&dclose->dlist);
+	kfree(dclose);
+}
+
+void
+cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
+{
+	struct cifsFileInfo *cfile = NULL;
+	struct file_list *tmp_list, *tmp_next_list;
+	struct list_head file_head;
+
+	if (cifs_inode == NULL)
+		return;
+
+	INIT_LIST_HEAD(&file_head);
+	spin_lock(&cifs_inode->open_file_lock);
+	list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
+		if (delayed_work_pending(&cfile->deferred)) {
+			if (cancel_delayed_work(&cfile->deferred)) {
+				spin_lock(&cifs_inode->deferred_lock);
+				cifs_del_deferred_close(cfile);
+				spin_unlock(&cifs_inode->deferred_lock);
+
+				tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
+				if (tmp_list == NULL)
+					break;
+				tmp_list->cfile = cfile;
+				list_add_tail(&tmp_list->list, &file_head);
+			}
+		}
+	}
+	spin_unlock(&cifs_inode->open_file_lock);
+
+	list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
+		_cifsFileInfo_put(tmp_list->cfile, false, false);
+		list_del(&tmp_list->list);
+		kfree(tmp_list);
+	}
+}
+
+void
+cifs_close_all_deferred_files(struct cifs_tcon *tcon)
+{
+	struct cifsFileInfo *cfile;
+	struct file_list *tmp_list, *tmp_next_list;
+	struct list_head file_head;
+
+	INIT_LIST_HEAD(&file_head);
+	spin_lock(&tcon->open_file_lock);
+	list_for_each_entry(cfile, &tcon->openFileList, tlist) {
+		if (delayed_work_pending(&cfile->deferred)) {
+			if (cancel_delayed_work(&cfile->deferred)) {
+				spin_lock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
+				cifs_del_deferred_close(cfile);
+				spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
+
+				tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
+				if (tmp_list == NULL)
+					break;
+				tmp_list->cfile = cfile;
+				list_add_tail(&tmp_list->list, &file_head);
+			}
+		}
+	}
+	spin_unlock(&tcon->open_file_lock);
+
+	list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
+		_cifsFileInfo_put(tmp_list->cfile, true, false);
+		list_del(&tmp_list->list);
+		kfree(tmp_list);
+	}
+}
+void
+cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon, const char *path)
+{
+	struct cifsFileInfo *cfile;
+	struct file_list *tmp_list, *tmp_next_list;
+	struct list_head file_head;
+	void *page;
+	const char *full_path;
+
+	INIT_LIST_HEAD(&file_head);
+	page = alloc_dentry_path();
+	spin_lock(&tcon->open_file_lock);
+	list_for_each_entry(cfile, &tcon->openFileList, tlist) {
+		full_path = build_path_from_dentry(cfile->dentry, page);
+		if (strstr(full_path, path)) {
+			if (delayed_work_pending(&cfile->deferred)) {
+				if (cancel_delayed_work(&cfile->deferred)) {
+					spin_lock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
+					cifs_del_deferred_close(cfile);
+					spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
+
+					tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
+					if (tmp_list == NULL)
+						break;
+					tmp_list->cfile = cfile;
+					list_add_tail(&tmp_list->list, &file_head);
+				}
+			}
+		}
+	}
+	spin_unlock(&tcon->open_file_lock);
+
+	list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
+		_cifsFileInfo_put(tmp_list->cfile, true, false);
+		list_del(&tmp_list->list);
+		kfree(tmp_list);
+	}
+	free_dentry_path(page);
+}
+
+/* parses DFS referral V3 structure
+ * caller is responsible for freeing target_nodes
+ * returns:
+ * - on success - 0
+ * - on failure - errno
+ */
+int
+parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size,
+		    unsigned int *num_of_nodes,
+		    struct dfs_info3_param **target_nodes,
+		    const struct nls_table *nls_codepage, int remap,
+		    const char *searchName, bool is_unicode)
+{
+	int i, rc = 0;
+	char *data_end;
+	struct dfs_referral_level_3 *ref;
+
+	*num_of_nodes = le16_to_cpu(rsp->NumberOfReferrals);
+
+	if (*num_of_nodes < 1) {
+		cifs_dbg(VFS, "num_referrals: must be at least > 0, but we get num_referrals = %d\n",
+			 *num_of_nodes);
+		rc = -EINVAL;
+		goto parse_DFS_referrals_exit;
+	}
+
+	ref = (struct dfs_referral_level_3 *) &(rsp->referrals);
+	if (ref->VersionNumber != cpu_to_le16(3)) {
+		cifs_dbg(VFS, "Referrals of V%d version are not supported, should be V3\n",
+			 le16_to_cpu(ref->VersionNumber));
+		rc = -EINVAL;
+		goto parse_DFS_referrals_exit;
+	}
+
+	/* get the upper boundary of the resp buffer */
+	data_end = (char *)rsp + rsp_size;
+
+	cifs_dbg(FYI, "num_referrals: %d dfs flags: 0x%x ...\n",
+		 *num_of_nodes, le32_to_cpu(rsp->DFSFlags));
+
+	*target_nodes = kcalloc(*num_of_nodes, sizeof(struct dfs_info3_param),
+				GFP_KERNEL);
+	if (*target_nodes == NULL) {
+		rc = -ENOMEM;
+		goto parse_DFS_referrals_exit;
+	}
+
+	/* collect necessary data from referrals */
+	for (i = 0; i < *num_of_nodes; i++) {
+		char *temp;
+		int max_len;
+		struct dfs_info3_param *node = (*target_nodes)+i;
+
+		node->flags = le32_to_cpu(rsp->DFSFlags);
+		if (is_unicode) {
+			__le16 *tmp = kmalloc(strlen(searchName)*2 + 2,
+						GFP_KERNEL);
+			if (tmp == NULL) {
+				rc = -ENOMEM;
+				goto parse_DFS_referrals_exit;
+			}
+			cifsConvertToUTF16((__le16 *) tmp, searchName,
+					   PATH_MAX, nls_codepage, remap);
+			node->path_consumed = cifs_utf16_bytes(tmp,
+					le16_to_cpu(rsp->PathConsumed),
+					nls_codepage);
+			kfree(tmp);
+		} else
+			node->path_consumed = le16_to_cpu(rsp->PathConsumed);
+
+		node->server_type = le16_to_cpu(ref->ServerType);
+		node->ref_flag = le16_to_cpu(ref->ReferralEntryFlags);
+
+		/* copy DfsPath */
+		temp = (char *)ref + le16_to_cpu(ref->DfsPathOffset);
+		max_len = data_end - temp;
+		node->path_name = cifs_strndup_from_utf16(temp, max_len,
+						is_unicode, nls_codepage);
+		if (!node->path_name) {
+			rc = -ENOMEM;
+			goto parse_DFS_referrals_exit;
+		}
+
+		/* copy link target UNC */
+		temp = (char *)ref + le16_to_cpu(ref->NetworkAddressOffset);
+		max_len = data_end - temp;
+		node->node_name = cifs_strndup_from_utf16(temp, max_len,
+						is_unicode, nls_codepage);
+		if (!node->node_name) {
+			rc = -ENOMEM;
+			goto parse_DFS_referrals_exit;
+		}
+
+		node->ttl = le32_to_cpu(ref->TimeToLive);
+
+		ref++;
+	}
+
+parse_DFS_referrals_exit:
+	if (rc) {
+		free_dfs_info_array(*target_nodes, *num_of_nodes);
+		*target_nodes = NULL;
+		*num_of_nodes = 0;
+	}
+	return rc;
+}
+
+struct cifs_aio_ctx *
+cifs_aio_ctx_alloc(void)
+{
+	struct cifs_aio_ctx *ctx;
+
+	/*
+	 * Must use kzalloc to initialize ctx->bv to NULL and ctx->direct_io
+	 * to false so that we know when we have to unreference pages within
+	 * cifs_aio_ctx_release()
+	 */
+	ctx = kzalloc(sizeof(struct cifs_aio_ctx), GFP_KERNEL);
+	if (!ctx)
+		return NULL;
+
+	INIT_LIST_HEAD(&ctx->list);
+	mutex_init(&ctx->aio_mutex);
+	init_completion(&ctx->done);
+	kref_init(&ctx->refcount);
+	return ctx;
+}
+
+void
+cifs_aio_ctx_release(struct kref *refcount)
+{
+	struct cifs_aio_ctx *ctx = container_of(refcount,
+					struct cifs_aio_ctx, refcount);
+
+	cifsFileInfo_put(ctx->cfile);
+
+	/*
+	 * ctx->bv is only set if setup_aio_ctx_iter() was call successfuly
+	 * which means that iov_iter_get_pages() was a success and thus that
+	 * we have taken reference on pages.
+	 */
+	if (ctx->bv) {
+		unsigned i;
+
+		for (i = 0; i < ctx->npages; i++) {
+			if (ctx->should_dirty)
+				set_page_dirty(ctx->bv[i].bv_page);
+			put_page(ctx->bv[i].bv_page);
+		}
+		kvfree(ctx->bv);
+	}
+
+	kfree(ctx);
+}
+
+#define CIFS_AIO_KMALLOC_LIMIT (1024 * 1024)
+
+int
+setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw)
+{
+	ssize_t rc;
+	unsigned int cur_npages;
+	unsigned int npages = 0;
+	unsigned int i;
+	size_t len;
+	size_t count = iov_iter_count(iter);
+	unsigned int saved_len;
+	size_t start;
+	unsigned int max_pages = iov_iter_npages(iter, INT_MAX);
+	struct page **pages = NULL;
+	struct bio_vec *bv = NULL;
+
+	if (iov_iter_is_kvec(iter)) {
+		memcpy(&ctx->iter, iter, sizeof(*iter));
+		ctx->len = count;
+		iov_iter_advance(iter, count);
+		return 0;
+	}
+
+	if (array_size(max_pages, sizeof(*bv)) <= CIFS_AIO_KMALLOC_LIMIT)
+		bv = kmalloc_array(max_pages, sizeof(*bv), GFP_KERNEL);
+
+	if (!bv) {
+		bv = vmalloc(array_size(max_pages, sizeof(*bv)));
+		if (!bv)
+			return -ENOMEM;
+	}
+
+	if (array_size(max_pages, sizeof(*pages)) <= CIFS_AIO_KMALLOC_LIMIT)
+		pages = kmalloc_array(max_pages, sizeof(*pages), GFP_KERNEL);
+
+	if (!pages) {
+		pages = vmalloc(array_size(max_pages, sizeof(*pages)));
+		if (!pages) {
+			kvfree(bv);
+			return -ENOMEM;
+		}
+	}
+
+	saved_len = count;
+
+	while (count && npages < max_pages) {
+		rc = iov_iter_get_pages2(iter, pages, count, max_pages, &start);
+		if (rc < 0) {
+			cifs_dbg(VFS, "Couldn't get user pages (rc=%zd)\n", rc);
+			break;
+		}
+
+		if (rc > count) {
+			cifs_dbg(VFS, "get pages rc=%zd more than %zu\n", rc,
+				 count);
+			break;
+		}
+
+		count -= rc;
+		rc += start;
+		cur_npages = DIV_ROUND_UP(rc, PAGE_SIZE);
+
+		if (npages + cur_npages > max_pages) {
+			cifs_dbg(VFS, "out of vec array capacity (%u vs %u)\n",
+				 npages + cur_npages, max_pages);
+			break;
+		}
+
+		for (i = 0; i < cur_npages; i++) {
+			len = rc > PAGE_SIZE ? PAGE_SIZE : rc;
+			bv[npages + i].bv_page = pages[i];
+			bv[npages + i].bv_offset = start;
+			bv[npages + i].bv_len = len - start;
+			rc -= len;
+			start = 0;
+		}
+
+		npages += cur_npages;
+	}
+
+	kvfree(pages);
+	ctx->bv = bv;
+	ctx->len = saved_len - count;
+	ctx->npages = npages;
+	iov_iter_bvec(&ctx->iter, rw, ctx->bv, npages, ctx->len);
+	return 0;
+}
+
+/**
+ * cifs_alloc_hash - allocate hash and hash context together
+ * @name: The name of the crypto hash algo
+ * @sdesc: SHASH descriptor where to put the pointer to the hash TFM
+ *
+ * The caller has to make sure @sdesc is initialized to either NULL or
+ * a valid context. It can be freed via cifs_free_hash().
+ */
+int
+cifs_alloc_hash(const char *name, struct shash_desc **sdesc)
+{
+	int rc = 0;
+	struct crypto_shash *alg = NULL;
+
+	if (*sdesc)
+		return 0;
+
+	alg = crypto_alloc_shash(name, 0, 0);
+	if (IS_ERR(alg)) {
+		cifs_dbg(VFS, "Could not allocate shash TFM '%s'\n", name);
+		rc = PTR_ERR(alg);
+		*sdesc = NULL;
+		return rc;
+	}
+
+	*sdesc = kmalloc(sizeof(struct shash_desc) + crypto_shash_descsize(alg), GFP_KERNEL);
+	if (*sdesc == NULL) {
+		cifs_dbg(VFS, "no memory left to allocate shash TFM '%s'\n", name);
+		crypto_free_shash(alg);
+		return -ENOMEM;
+	}
+
+	(*sdesc)->tfm = alg;
+	return 0;
+}
+
+/**
+ * cifs_free_hash - free hash and hash context together
+ * @sdesc: Where to find the pointer to the hash TFM
+ *
+ * Freeing a NULL descriptor is safe.
+ */
+void
+cifs_free_hash(struct shash_desc **sdesc)
+{
+	if (unlikely(!sdesc) || !*sdesc)
+		return;
+
+	if ((*sdesc)->tfm) {
+		crypto_free_shash((*sdesc)->tfm);
+		(*sdesc)->tfm = NULL;
+	}
+
+	kfree_sensitive(*sdesc);
+	*sdesc = NULL;
+}
+
+/**
+ * rqst_page_get_length - obtain the length and offset for a page in smb_rqst
+ * @rqst: The request descriptor
+ * @page: The index of the page to query
+ * @len: Where to store the length for this page:
+ * @offset: Where to store the offset for this page
+ */
+void rqst_page_get_length(const struct smb_rqst *rqst, unsigned int page,
+			  unsigned int *len, unsigned int *offset)
+{
+	*len = rqst->rq_pagesz;
+	*offset = (page == 0) ? rqst->rq_offset : 0;
+
+	if (rqst->rq_npages == 1 || page == rqst->rq_npages-1)
+		*len = rqst->rq_tailsz;
+	else if (page == 0)
+		*len = rqst->rq_pagesz - rqst->rq_offset;
+}
+
+void extract_unc_hostname(const char *unc, const char **h, size_t *len)
+{
+	const char *end;
+
+	/* skip initial slashes */
+	while (*unc && (*unc == '\\' || *unc == '/'))
+		unc++;
+
+	end = unc;
+
+	while (*end && !(*end == '\\' || *end == '/'))
+		end++;
+
+	*h = unc;
+	*len = end - unc;
+}
+
+/**
+ * copy_path_name - copy src path to dst, possibly truncating
+ * @dst: The destination buffer
+ * @src: The source name
+ *
+ * returns number of bytes written (including trailing nul)
+ */
+int copy_path_name(char *dst, const char *src)
+{
+	int name_len;
+
+	/*
+	 * PATH_MAX includes nul, so if strlen(src) >= PATH_MAX it
+	 * will truncate and strlen(dst) will be PATH_MAX-1
+	 */
+	name_len = strscpy(dst, src, PATH_MAX);
+	if (WARN_ON_ONCE(name_len < 0))
+		name_len = PATH_MAX-1;
+
+	/* we count the trailing nul */
+	name_len++;
+	return name_len;
+}
+
+struct super_cb_data {
+	void *data;
+	struct super_block *sb;
+};
+
+static void tcp_super_cb(struct super_block *sb, void *arg)
+{
+	struct super_cb_data *sd = arg;
+	struct TCP_Server_Info *server = sd->data;
+	struct cifs_sb_info *cifs_sb;
+	struct cifs_tcon *tcon;
+
+	if (sd->sb)
+		return;
+
+	cifs_sb = CIFS_SB(sb);
+	tcon = cifs_sb_master_tcon(cifs_sb);
+	if (tcon->ses->server == server)
+		sd->sb = sb;
+}
+
+static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void *),
+					    void *data)
+{
+	struct super_cb_data sd = {
+		.data = data,
+		.sb = NULL,
+	};
+	struct file_system_type **fs_type = (struct file_system_type *[]) {
+		&cifs_fs_type, &smb3_fs_type, NULL,
+	};
+
+	for (; *fs_type; fs_type++) {
+		iterate_supers_type(*fs_type, f, &sd);
+		if (sd.sb) {
+			/*
+			 * Grab an active reference in order to prevent automounts (DFS links)
+			 * of expiring and then freeing up our cifs superblock pointer while
+			 * we're doing failover.
+			 */
+			cifs_sb_active(sd.sb);
+			return sd.sb;
+		}
+	}
+	return ERR_PTR(-EINVAL);
+}
+
+static void __cifs_put_super(struct super_block *sb)
+{
+	if (!IS_ERR_OR_NULL(sb))
+		cifs_sb_deactive(sb);
+}
+
+struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server)
+{
+	return __cifs_get_super(tcp_super_cb, server);
+}
+
+void cifs_put_tcp_super(struct super_block *sb)
+{
+	__cifs_put_super(sb);
+}
+
+#ifdef CONFIG_CIFS_DFS_UPCALL
+int match_target_ip(struct TCP_Server_Info *server,
+		    const char *share, size_t share_len,
+		    bool *result)
+{
+	int rc;
+	char *target, *tip = NULL;
+	struct sockaddr tipaddr;
+
+	*result = false;
+
+	target = kzalloc(share_len + 3, GFP_KERNEL);
+	if (!target) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	scnprintf(target, share_len + 3, "\\\\%.*s", (int)share_len, share);
+
+	cifs_dbg(FYI, "%s: target name: %s\n", __func__, target + 2);
+
+	rc = dns_resolve_server_name_to_ip(target, &tip, NULL);
+	if (rc < 0)
+		goto out;
+
+	cifs_dbg(FYI, "%s: target ip: %s\n", __func__, tip);
+
+	if (!cifs_convert_address(&tipaddr, tip, strlen(tip))) {
+		cifs_dbg(VFS, "%s: failed to convert target ip address\n",
+			 __func__);
+		rc = -EINVAL;
+		goto out;
+	}
+
+	*result = cifs_match_ipaddr((struct sockaddr *)&server->dstaddr,
+				    &tipaddr);
+	cifs_dbg(FYI, "%s: ip addresses match: %u\n", __func__, *result);
+	rc = 0;
+
+out:
+	kfree(target);
+	kfree(tip);
+
+	return rc;
+}
+
+int cifs_update_super_prepath(struct cifs_sb_info *cifs_sb, char *prefix)
+{
+	kfree(cifs_sb->prepath);
+
+	if (prefix && *prefix) {
+		cifs_sb->prepath = cifs_sanitize_prepath(prefix, GFP_ATOMIC);
+		if (!cifs_sb->prepath)
+			return -ENOMEM;
+
+		convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb));
+	} else
+		cifs_sb->prepath = NULL;
+
+	cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
+	return 0;
+}
+
+/*
+ * Handle weird Windows SMB server behaviour. It responds with
+ * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request for
+ * "\<server>\<dfsname>\<linkpath>" DFS reference, where <dfsname> contains
+ * non-ASCII unicode symbols.
+ */
+int cifs_inval_name_dfs_link_error(const unsigned int xid,
+				   struct cifs_tcon *tcon,
+				   struct cifs_sb_info *cifs_sb,
+				   const char *full_path,
+				   bool *islink)
+{
+	struct cifs_ses *ses = tcon->ses;
+	size_t len;
+	char *path;
+	char *ref_path;
+
+	*islink = false;
+
+	/*
+	 * Fast path - skip check when @full_path doesn't have a prefix path to
+	 * look up or tcon is not DFS.
+	 */
+	if (strlen(full_path) < 2 || !cifs_sb ||
+	    (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) ||
+	    !is_tcon_dfs(tcon) || !ses->server->origin_fullpath)
+		return 0;
+
+	/*
+	 * Slow path - tcon is DFS and @full_path has prefix path, so attempt
+	 * to get a referral to figure out whether it is an DFS link.
+	 */
+	len = strnlen(tcon->tree_name, MAX_TREE_SIZE + 1) + strlen(full_path) + 1;
+	path = kmalloc(len, GFP_KERNEL);
+	if (!path)
+		return -ENOMEM;
+
+	scnprintf(path, len, "%s%s", tcon->tree_name, full_path);
+	ref_path = dfs_cache_canonical_path(path + 1, cifs_sb->local_nls,
+					    cifs_remap(cifs_sb));
+	kfree(path);
+
+	if (IS_ERR(ref_path)) {
+		if (PTR_ERR(ref_path) != -EINVAL)
+			return PTR_ERR(ref_path);
+	} else {
+		struct dfs_info3_param *refs = NULL;
+		int num_refs = 0;
+
+		/*
+		 * XXX: we are not using dfs_cache_find() here because we might
+		 * end filling all the DFS cache and thus potentially
+		 * removing cached DFS targets that the client would eventually
+		 * need during failover.
+		 */
+		if (ses->server->ops->get_dfs_refer &&
+		    !ses->server->ops->get_dfs_refer(xid, ses, ref_path, &refs,
+						     &num_refs, cifs_sb->local_nls,
+						     cifs_remap(cifs_sb)))
+			*islink = refs[0].server_type == DFS_TYPE_LINK;
+		free_dfs_info_array(refs, num_refs);
+		kfree(ref_path);
+	}
+	return 0;
+}
+#endif
+
+int cifs_wait_for_server_reconnect(struct TCP_Server_Info *server, bool retry)
+{
+	int timeout = 10;
+	int rc;
+
+	spin_lock(&server->srv_lock);
+	if (server->tcpStatus != CifsNeedReconnect) {
+		spin_unlock(&server->srv_lock);
+		return 0;
+	}
+	timeout *= server->nr_targets;
+	spin_unlock(&server->srv_lock);
+
+	/*
+	 * Give demultiplex thread up to 10 seconds to each target available for
+	 * reconnect -- should be greater than cifs socket timeout which is 7
+	 * seconds.
+	 *
+	 * On "soft" mounts we wait once. Hard mounts keep retrying until
+	 * process is killed or server comes back on-line.
+	 */
+	do {
+		rc = wait_event_interruptible_timeout(server->response_q,
+						      (server->tcpStatus != CifsNeedReconnect),
+						      timeout * HZ);
+		if (rc < 0) {
+			cifs_dbg(FYI, "%s: aborting reconnect due to received signal\n",
+				 __func__);
+			return -ERESTARTSYS;
+		}
+
+		/* are we still trying to reconnect? */
+		spin_lock(&server->srv_lock);
+		if (server->tcpStatus != CifsNeedReconnect) {
+			spin_unlock(&server->srv_lock);
+			return 0;
+		}
+		spin_unlock(&server->srv_lock);
+	} while (retry);
+
+	cifs_dbg(FYI, "%s: gave up waiting on reconnect\n", __func__);
+	return -EHOSTDOWN;
+}