Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[cris-mirror.git] / fs / cifs / smb2misc.c

/*
 *   fs/cifs/smb2misc.c
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2011
 *                 Etersoft, 2012
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *              Pavel Shilovsky (pshilovsky@samba.org) 2012
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
#include <linux/ctype.h>
#include "smb2pdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "smb2proto.h"
#include "cifs_debug.h"
#include "cifs_unicode.h"
#include "smb2status.h"
#include "smb2glob.h"

static int
check_smb2_hdr(struct smb2_sync_hdr *shdr, __u64 mid)
{
        __u64 wire_mid = le64_to_cpu(shdr->MessageId);

        /*
         * Make sure that this really is an SMB, that it is a response,
         * and that the message ids match.
         */
        if ((shdr->ProtocolId == SMB2_PROTO_NUMBER) &&
            (mid == wire_mid)) {
                if (shdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
                        return 0;
                else {
                        /* only one valid case where server sends us request */
                        if (shdr->Command == SMB2_OPLOCK_BREAK)
                                return 0;
                        else
                                cifs_dbg(VFS, "Received Request not response\n");
                }
        } else { /* bad signature or mid */
                if (shdr->ProtocolId != SMB2_PROTO_NUMBER)
                        cifs_dbg(VFS, "Bad protocol string signature header %x\n",
                                 le32_to_cpu(shdr->ProtocolId));
                if (mid != wire_mid)
                        cifs_dbg(VFS, "Mids do not match: %llu and %llu\n",
                                 mid, wire_mid);
        }
        cifs_dbg(VFS, "Bad SMB detected. The Mid=%llu\n", wire_mid);
        return 1;
}

/*
 *  The following table defines the expected "StructureSize" of SMB2 responses
 *  in order by SMB2 command.  This is similar to "wct" in SMB/CIFS responses.
 *
 *  Note that commands are defined in smb2pdu.h in le16 but the array below is
 *  indexed by command in host byte order
 */
static const __le16 smb2_rsp_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {
        /* SMB2_NEGOTIATE */ cpu_to_le16(65),
        /* SMB2_SESSION_SETUP */ cpu_to_le16(9),
        /* SMB2_LOGOFF */ cpu_to_le16(4),
        /* SMB2_TREE_CONNECT */ cpu_to_le16(16),
        /* SMB2_TREE_DISCONNECT */ cpu_to_le16(4),
        /* SMB2_CREATE */ cpu_to_le16(89),
        /* SMB2_CLOSE */ cpu_to_le16(60),
        /* SMB2_FLUSH */ cpu_to_le16(4),
        /* SMB2_READ */ cpu_to_le16(17),
        /* SMB2_WRITE */ cpu_to_le16(17),
        /* SMB2_LOCK */ cpu_to_le16(4),
        /* SMB2_IOCTL */ cpu_to_le16(49),
        /* BB CHECK this ... not listed in documentation */
        /* SMB2_CANCEL */ cpu_to_le16(0),
        /* SMB2_ECHO */ cpu_to_le16(4),
        /* SMB2_QUERY_DIRECTORY */ cpu_to_le16(9),
        /* SMB2_CHANGE_NOTIFY */ cpu_to_le16(9),
        /* SMB2_QUERY_INFO */ cpu_to_le16(9),
        /* SMB2_SET_INFO */ cpu_to_le16(2),
        /* BB FIXME can also be 44 for lease break */
        /* SMB2_OPLOCK_BREAK */ cpu_to_le16(24)
};

int
smb2_check_message(char *buf, unsigned int length, struct TCP_Server_Info *srvr)
{
        struct smb2_pdu *pdu = (struct smb2_pdu *)buf;
        struct smb2_hdr *hdr = &pdu->hdr;
        struct smb2_sync_hdr *shdr = get_sync_hdr(buf);
        __u64 mid;
        __u32 len = get_rfc1002_length(buf);
        __u32 clc_len;  /* calculated length */
        int command;

        /* BB disable following printk later */
        cifs_dbg(FYI, "%s length: 0x%x, smb_buf_length: 0x%x\n",
                 __func__, length, len);

        /*
         * Add function to do table lookup of StructureSize by command
         * ie Validate the wct via smb2_struct_sizes table above
         */

        if (shdr->ProtocolId == SMB2_TRANSFORM_PROTO_NUM) {
                struct smb2_transform_hdr *thdr =
                        (struct smb2_transform_hdr *)buf;
                struct cifs_ses *ses = NULL;
                struct list_head *tmp;

                /* decrypt frame now that it is completely read in */
                spin_lock(&cifs_tcp_ses_lock);
                list_for_each(tmp, &srvr->smb_ses_list) {
                        ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
                        if (ses->Suid == thdr->SessionId)
                                break;

                        ses = NULL;
                }
                spin_unlock(&cifs_tcp_ses_lock);
                if (ses == NULL) {
                        cifs_dbg(VFS, "no decryption - session id not found\n");
                        return 1;
                }
        }

        mid = le64_to_cpu(shdr->MessageId);
        if (length < sizeof(struct smb2_pdu)) {
                if ((length >= sizeof(struct smb2_hdr))
                    && (shdr->Status != 0)) {
                        pdu->StructureSize2 = 0;
                        /*
                         * As with SMB/CIFS, on some error cases servers may
                         * not return wct properly
                         */
                        return 0;
                } else {
                        cifs_dbg(VFS, "Length less than SMB header size\n");
                }
                return 1;
        }
        if (len > CIFSMaxBufSize + MAX_SMB2_HDR_SIZE - 4) {
                cifs_dbg(VFS, "SMB length greater than maximum, mid=%llu\n",
                         mid);
                return 1;
        }

        if (check_smb2_hdr(shdr, mid))
                return 1;

        if (shdr->StructureSize != SMB2_HEADER_STRUCTURE_SIZE) {
                cifs_dbg(VFS, "Illegal structure size %u\n",
                         le16_to_cpu(shdr->StructureSize));
                return 1;
        }

        command = le16_to_cpu(shdr->Command);
        if (command >= NUMBER_OF_SMB2_COMMANDS) {
                cifs_dbg(VFS, "Illegal SMB2 command %d\n", command);
                return 1;
        }

        if (smb2_rsp_struct_sizes[command] != pdu->StructureSize2) {
                if (command != SMB2_OPLOCK_BREAK_HE && (shdr->Status == 0 ||
                    pdu->StructureSize2 != SMB2_ERROR_STRUCTURE_SIZE2)) {
                        /* error packets have 9 byte structure size */
                        cifs_dbg(VFS, "Illegal response size %u for command %d\n",
                                 le16_to_cpu(pdu->StructureSize2), command);
                        return 1;
                } else if (command == SMB2_OPLOCK_BREAK_HE
                           && (shdr->Status == 0)
                           && (le16_to_cpu(pdu->StructureSize2) != 44)
                           && (le16_to_cpu(pdu->StructureSize2) != 36)) {
                        /* special case for SMB2.1 lease break message */
                        cifs_dbg(VFS, "Illegal response size %d for oplock break\n",
                                 le16_to_cpu(pdu->StructureSize2));
                        return 1;
                }
        }

        if (4 + len != length) {
                cifs_dbg(VFS, "Total length %u RFC1002 length %u mismatch mid %llu\n",
                         length, 4 + len, mid);
                return 1;
        }

        clc_len = smb2_calc_size(hdr);

        if (4 + len != clc_len) {
                cifs_dbg(FYI, "Calculated size %u length %u mismatch mid %llu\n",
                         clc_len, 4 + len, mid);
                /* create failed on symlink */
                if (command == SMB2_CREATE_HE &&
                    shdr->Status == STATUS_STOPPED_ON_SYMLINK)
                        return 0;
                /* Windows 7 server returns 24 bytes more */
                if (clc_len + 20 == len && command == SMB2_OPLOCK_BREAK_HE)
                        return 0;
                /* server can return one byte more due to implied bcc[0] */
                if (clc_len == 4 + len + 1)
                        return 0;

                /*
                 * MacOS server pads after SMB2.1 write response with 3 bytes
                 * of junk. Other servers match RFC1001 len to actual
                 * SMB2/SMB3 frame length (header + smb2 response specific data)
                 * Log the server error (once), but allow it and continue
                 * since the frame is parseable.
                 */
                if (clc_len < 4 /* RFC1001 header size */ + len) {
                        printk_once(KERN_WARNING
                                "SMB2 server sent bad RFC1001 len %d not %d\n",
                                len, clc_len - 4);
                        return 0;
                }

                return 1;
        }
        return 0;
}

/*
 * The size of the variable area depends on the offset and length fields
 * located in different fields for various SMB2 responses. SMB2 responses
 * with no variable length info, show an offset of zero for the offset field.
 */
static const bool has_smb2_data_area[NUMBER_OF_SMB2_COMMANDS] = {
        /* SMB2_NEGOTIATE */ true,
        /* SMB2_SESSION_SETUP */ true,
        /* SMB2_LOGOFF */ false,
        /* SMB2_TREE_CONNECT */ false,
        /* SMB2_TREE_DISCONNECT */ false,
        /* SMB2_CREATE */ true,
        /* SMB2_CLOSE */ false,
        /* SMB2_FLUSH */ false,
        /* SMB2_READ */ true,
        /* SMB2_WRITE */ false,
        /* SMB2_LOCK */ false,
        /* SMB2_IOCTL */ true,
        /* SMB2_CANCEL */ false, /* BB CHECK this not listed in documentation */
        /* SMB2_ECHO */ false,
        /* SMB2_QUERY_DIRECTORY */ true,
        /* SMB2_CHANGE_NOTIFY */ true,
        /* SMB2_QUERY_INFO */ true,
        /* SMB2_SET_INFO */ false,
        /* SMB2_OPLOCK_BREAK */ false
};

/*
 * Returns the pointer to the beginning of the data area. Length of the data
 * area and the offset to it (from the beginning of the smb are also returned.
 */
char *
smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)
{
        struct smb2_sync_hdr *shdr = get_sync_hdr(hdr);
        *off = 0;
        *len = 0;

        /* error responses do not have data area */
        if (shdr->Status && shdr->Status != STATUS_MORE_PROCESSING_REQUIRED &&
            (((struct smb2_err_rsp *)hdr)->StructureSize) ==
                                                SMB2_ERROR_STRUCTURE_SIZE2)
                return NULL;

        /*
         * Following commands have data areas so we have to get the location
         * of the data buffer offset and data buffer length for the particular
         * command.
         */
        switch (shdr->Command) {
        case SMB2_NEGOTIATE:
                *off = le16_to_cpu(
                    ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferOffset);
                *len = le16_to_cpu(
                    ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferLength);
                break;
        case SMB2_SESSION_SETUP:
                *off = le16_to_cpu(
                    ((struct smb2_sess_setup_rsp *)hdr)->SecurityBufferOffset);
                *len = le16_to_cpu(
                    ((struct smb2_sess_setup_rsp *)hdr)->SecurityBufferLength);
                break;
        case SMB2_CREATE:
                *off = le32_to_cpu(
                    ((struct smb2_create_rsp *)hdr)->CreateContextsOffset);
                *len = le32_to_cpu(
                    ((struct smb2_create_rsp *)hdr)->CreateContextsLength);
                break;
        case SMB2_QUERY_INFO:
                *off = le16_to_cpu(
                    ((struct smb2_query_info_rsp *)hdr)->OutputBufferOffset);
                *len = le32_to_cpu(
                    ((struct smb2_query_info_rsp *)hdr)->OutputBufferLength);
                break;
        case SMB2_READ:
                *off = ((struct smb2_read_rsp *)hdr)->DataOffset;
                *len = le32_to_cpu(((struct smb2_read_rsp *)hdr)->DataLength);
                break;
        case SMB2_QUERY_DIRECTORY:
                *off = le16_to_cpu(
                  ((struct smb2_query_directory_rsp *)hdr)->OutputBufferOffset);
                *len = le32_to_cpu(
                  ((struct smb2_query_directory_rsp *)hdr)->OutputBufferLength);
                break;
        case SMB2_IOCTL:
                *off = le32_to_cpu(
                  ((struct smb2_ioctl_rsp *)hdr)->OutputOffset);
                *len = le32_to_cpu(((struct smb2_ioctl_rsp *)hdr)->OutputCount);
                break;
        case SMB2_CHANGE_NOTIFY:
        default:
                /* BB FIXME for unimplemented cases above */
                cifs_dbg(VFS, "no length check for command\n");
                break;
        }

        /*
         * Invalid length or offset probably means data area is invalid, but
         * we have little choice but to ignore the data area in this case.
         */
        if (*off > 4096) {
                cifs_dbg(VFS, "offset %d too large, data area ignored\n", *off);
                *len = 0;
                *off = 0;
        } else if (*off < 0) {
                cifs_dbg(VFS, "negative offset %d to data invalid ignore data area\n",
                         *off);
                *off = 0;
                *len = 0;
        } else if (*len < 0) {
                cifs_dbg(VFS, "negative data length %d invalid, data area ignored\n",
                         *len);
                *len = 0;
        } else if (*len > 128 * 1024) {
                cifs_dbg(VFS, "data area larger than 128K: %d\n", *len);
                *len = 0;
        }

        /* return pointer to beginning of data area, ie offset from SMB start */
        if ((*off != 0) && (*len != 0))
                return (char *)shdr + *off;
        else
                return NULL;
}

/*
 * 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
smb2_calc_size(void *buf)
{
        struct smb2_pdu *pdu = (struct smb2_pdu *)buf;
        struct smb2_hdr *hdr = &pdu->hdr;
        struct smb2_sync_hdr *shdr = get_sync_hdr(hdr);
        int offset; /* the offset from the beginning of SMB to data area */
        int data_length; /* the length of the variable length data area */
        /* Structure Size has already been checked to make sure it is 64 */
        int len = 4 + le16_to_cpu(shdr->StructureSize);

        /*
         * StructureSize2, ie length of fixed parameter area has already
         * been checked to make sure it is the correct length.
         */
        len += le16_to_cpu(pdu->StructureSize2);

        if (has_smb2_data_area[le16_to_cpu(shdr->Command)] == false)
                goto calc_size_exit;

        smb2_get_data_area_len(&offset, &data_length, hdr);
        cifs_dbg(FYI, "SMB2 data length %d offset %d\n", data_length, offset);

        if (data_length > 0) {
                /*
                 * Check to make sure that data area begins after fixed area,
                 * Note that last byte of the fixed area is part of data area
                 * for some commands, typically those with odd StructureSize,
                 * so we must add one to the calculation (and 4 to account for
                 * the size of the RFC1001 hdr.
                 */
                if (offset + 4 + 1 < len) {
                        cifs_dbg(VFS, "data area offset %d overlaps SMB2 header %d\n",
                                 offset + 4 + 1, len);
                        data_length = 0;
                } else {
                        len = 4 + offset + data_length;
                }
        }
calc_size_exit:
        cifs_dbg(FYI, "SMB2 len %d\n", len);
        return len;
}

/* Note: caller must free return buffer */
__le16 *
cifs_convert_path_to_utf16(const char *from, struct cifs_sb_info *cifs_sb)
{
        int len;
        const char *start_of_path;
        __le16 *to;
        int map_type;

        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SFM_CHR)
                map_type = SFM_MAP_UNI_RSVD;
        else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR)
                map_type = SFU_MAP_UNI_RSVD;
        else
                map_type = NO_MAP_UNI_RSVD;

        /* Windows doesn't allow paths beginning with \ */
        if (from[0] == '\\')
                start_of_path = from + 1;
        else
                start_of_path = from;
        to = cifs_strndup_to_utf16(start_of_path, PATH_MAX, &len,
                                   cifs_sb->local_nls, map_type);
        return to;
}

__le32
smb2_get_lease_state(struct cifsInodeInfo *cinode)
{
        __le32 lease = 0;

        if (CIFS_CACHE_WRITE(cinode))
                lease |= SMB2_LEASE_WRITE_CACHING;
        if (CIFS_CACHE_HANDLE(cinode))
                lease |= SMB2_LEASE_HANDLE_CACHING;
        if (CIFS_CACHE_READ(cinode))
                lease |= SMB2_LEASE_READ_CACHING;
        return lease;
}

struct smb2_lease_break_work {
        struct work_struct lease_break;
        struct tcon_link *tlink;
        __u8 lease_key[16];
        __le32 lease_state;
};

static void
cifs_ses_oplock_break(struct work_struct *work)
{
        struct smb2_lease_break_work *lw = container_of(work,
                                struct smb2_lease_break_work, lease_break);
        int rc;

        rc = SMB2_lease_break(0, tlink_tcon(lw->tlink), lw->lease_key,
                              lw->lease_state);
        cifs_dbg(FYI, "Lease release rc %d\n", rc);
        cifs_put_tlink(lw->tlink);
        kfree(lw);
}

static bool
smb2_tcon_has_lease(struct cifs_tcon *tcon, struct smb2_lease_break *rsp,
                    struct smb2_lease_break_work *lw)
{
        bool found;
        __u8 lease_state;
        struct list_head *tmp;
        struct cifsFileInfo *cfile;
        struct TCP_Server_Info *server = tcon->ses->server;
        struct cifs_pending_open *open;
        struct cifsInodeInfo *cinode;
        int ack_req = le32_to_cpu(rsp->Flags &
                                  SMB2_NOTIFY_BREAK_LEASE_FLAG_ACK_REQUIRED);

        lease_state = le32_to_cpu(rsp->NewLeaseState);

        list_for_each(tmp, &tcon->openFileList) {
                cfile = list_entry(tmp, struct cifsFileInfo, tlist);
                cinode = CIFS_I(d_inode(cfile->dentry));

                if (memcmp(cinode->lease_key, rsp->LeaseKey,
                                                        SMB2_LEASE_KEY_SIZE))
                        continue;

                cifs_dbg(FYI, "found in the open list\n");
                cifs_dbg(FYI, "lease key match, lease break 0x%x\n",
                         le32_to_cpu(rsp->NewLeaseState));

                server->ops->set_oplock_level(cinode, lease_state, 0, NULL);

                if (ack_req)
                        cfile->oplock_break_cancelled = false;
                else
                        cfile->oplock_break_cancelled = true;

                queue_work(cifsoplockd_wq, &cfile->oplock_break);
                kfree(lw);
                return true;
        }

        found = false;
        list_for_each_entry(open, &tcon->pending_opens, olist) {
                if (memcmp(open->lease_key, rsp->LeaseKey,
                           SMB2_LEASE_KEY_SIZE))
                        continue;

                if (!found && ack_req) {
                        found = true;
                        memcpy(lw->lease_key, open->lease_key,
                               SMB2_LEASE_KEY_SIZE);
                        lw->tlink = cifs_get_tlink(open->tlink);
                        queue_work(cifsiod_wq, &lw->lease_break);
                }

                cifs_dbg(FYI, "found in the pending open list\n");
                cifs_dbg(FYI, "lease key match, lease break 0x%x\n",
                         le32_to_cpu(rsp->NewLeaseState));

                open->oplock = lease_state;
        }
        return found;
}

static bool
smb2_is_valid_lease_break(char *buffer)
{
        struct smb2_lease_break *rsp = (struct smb2_lease_break *)buffer;
        struct list_head *tmp, *tmp1, *tmp2;
        struct TCP_Server_Info *server;
        struct cifs_ses *ses;
        struct cifs_tcon *tcon;
        struct smb2_lease_break_work *lw;

        lw = kmalloc(sizeof(struct smb2_lease_break_work), GFP_KERNEL);
        if (!lw)
                return false;

        INIT_WORK(&lw->lease_break, cifs_ses_oplock_break);
        lw->lease_state = rsp->NewLeaseState;

        cifs_dbg(FYI, "Checking for lease break\n");

        /* look up tcon based on tid & uid */
        spin_lock(&cifs_tcp_ses_lock);
        list_for_each(tmp, &cifs_tcp_ses_list) {
                server = list_entry(tmp, struct TCP_Server_Info, tcp_ses_list);

                list_for_each(tmp1, &server->smb_ses_list) {
                        ses = list_entry(tmp1, struct cifs_ses, smb_ses_list);

                        list_for_each(tmp2, &ses->tcon_list) {
                                tcon = list_entry(tmp2, struct cifs_tcon,
                                                  tcon_list);
                                spin_lock(&tcon->open_file_lock);
                                cifs_stats_inc(
                                    &tcon->stats.cifs_stats.num_oplock_brks);
                                if (smb2_tcon_has_lease(tcon, rsp, lw)) {
                                        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);
        kfree(lw);
        cifs_dbg(FYI, "Can not process lease break - no lease matched\n");
        return false;
}

bool
smb2_is_valid_oplock_break(char *buffer, struct TCP_Server_Info *server)
{
        struct smb2_oplock_break_rsp *rsp = (struct smb2_oplock_break_rsp *)buffer;
        struct list_head *tmp, *tmp1, *tmp2;
        struct cifs_ses *ses;
        struct cifs_tcon *tcon;
        struct cifsInodeInfo *cinode;
        struct cifsFileInfo *cfile;

        cifs_dbg(FYI, "Checking for oplock break\n");

        if (rsp->hdr.sync_hdr.Command != SMB2_OPLOCK_BREAK)
                return false;

        if (rsp->StructureSize !=
                                smb2_rsp_struct_sizes[SMB2_OPLOCK_BREAK_HE]) {
                if (le16_to_cpu(rsp->StructureSize) == 44)
                        return smb2_is_valid_lease_break(buffer);
                else
                        return false;
        }

        cifs_dbg(FYI, "oplock level 0x%x\n", rsp->OplockLevel);

        /* look up tcon based on tid & uid */
        spin_lock(&cifs_tcp_ses_lock);
        list_for_each(tmp, &server->smb_ses_list) {
                ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
                list_for_each(tmp1, &ses->tcon_list) {
                        tcon = list_entry(tmp1, struct cifs_tcon, tcon_list);

                        cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
                        spin_lock(&tcon->open_file_lock);
                        list_for_each(tmp2, &tcon->openFileList) {
                                cfile = list_entry(tmp2, struct cifsFileInfo,
                                                     tlist);
                                if (rsp->PersistentFid !=
                                    cfile->fid.persistent_fid ||
                                    rsp->VolatileFid !=
                                    cfile->fid.volatile_fid)
                                        continue;

                                cifs_dbg(FYI, "file id match, oplock break\n");
                                cinode = CIFS_I(d_inode(cfile->dentry));
                                spin_lock(&cfile->file_info_lock);
                                if (!CIFS_CACHE_WRITE(cinode) &&
                                    rsp->OplockLevel == SMB2_OPLOCK_LEVEL_NONE)
                                        cfile->oplock_break_cancelled = true;
                                else
                                        cfile->oplock_break_cancelled = false;

                                set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
                                        &cinode->flags);

                                /*
                                 * Set flag if the server downgrades the oplock
                                 * to L2 else clear.
                                 */
                                if (rsp->OplockLevel)
                                        set_bit(
                                           CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
                                           &cinode->flags);
                                else
                                        clear_bit(
                                           CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
                                           &cinode->flags);
                                spin_unlock(&cfile->file_info_lock);
                                queue_work(cifsoplockd_wq,
                                           &cfile->oplock_break);

                                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 false;
}

void
smb2_cancelled_close_fid(struct work_struct *work)
{
        struct close_cancelled_open *cancelled = container_of(work,
                                        struct close_cancelled_open, work);

        cifs_dbg(VFS, "Close unmatched open\n");

        SMB2_close(0, cancelled->tcon, cancelled->fid.persistent_fid,
                   cancelled->fid.volatile_fid);
        cifs_put_tcon(cancelled->tcon);
        kfree(cancelled);
}

int
smb2_handle_cancelled_mid(char *buffer, struct TCP_Server_Info *server)
{
        struct smb2_sync_hdr *sync_hdr = get_sync_hdr(buffer);
        struct smb2_create_rsp *rsp = (struct smb2_create_rsp *)buffer;
        struct cifs_tcon *tcon;
        struct close_cancelled_open *cancelled;

        if (sync_hdr->Command != SMB2_CREATE ||
            sync_hdr->Status != STATUS_SUCCESS)
                return 0;

        cancelled = kzalloc(sizeof(*cancelled), GFP_KERNEL);
        if (!cancelled)
                return -ENOMEM;

        tcon = smb2_find_smb_tcon(server, sync_hdr->SessionId,
                                  sync_hdr->TreeId);
        if (!tcon) {
                kfree(cancelled);
                return -ENOENT;
        }

        cancelled->fid.persistent_fid = rsp->PersistentFileId;
        cancelled->fid.volatile_fid = rsp->VolatileFileId;
        cancelled->tcon = tcon;
        INIT_WORK(&cancelled->work, smb2_cancelled_close_fid);
        queue_work(cifsiod_wq, &cancelled->work);

        return 0;
}