// SPDX-License-Identifier: LGPL-2.1
/*
 *
 *   vfs operations that deal with files
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2010
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *              Jeremy Allison (jra@samba.org)
 *
 */
#include <linux/fs.h>
#include <linux/backing-dev.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/pagemap.h>
#include <linux/pagevec.h>
#include <linux/writeback.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/delay.h>
#include <linux/mount.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/mm.h>
#include <asm/div64.h>
#include "cifsfs.h"
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_unicode.h"
#include "cifs_debug.h"
#include "cifs_fs_sb.h"
#include "fscache.h"
#include "smbdirect.h"
#include "fs_context.h"
#include "cifs_ioctl.h"

static inline int cifs_convert_flags(unsigned int flags)
{
        if ((flags & O_ACCMODE) == O_RDONLY)
                return GENERIC_READ;
        else if ((flags & O_ACCMODE) == O_WRONLY)
                return GENERIC_WRITE;
        else if ((flags & O_ACCMODE) == O_RDWR) {
                /* GENERIC_ALL is too much permission to request
                   can cause unnecessary access denied on create */
                /* return GENERIC_ALL; */
                return (GENERIC_READ | GENERIC_WRITE);
        }

        return (READ_CONTROL | FILE_WRITE_ATTRIBUTES | FILE_READ_ATTRIBUTES |
                FILE_WRITE_EA | FILE_APPEND_DATA | FILE_WRITE_DATA |
                FILE_READ_DATA);
}

static u32 cifs_posix_convert_flags(unsigned int flags)
{
        u32 posix_flags = 0;

        if ((flags & O_ACCMODE) == O_RDONLY)
                posix_flags = SMB_O_RDONLY;
        else if ((flags & O_ACCMODE) == O_WRONLY)
                posix_flags = SMB_O_WRONLY;
        else if ((flags & O_ACCMODE) == O_RDWR)
                posix_flags = SMB_O_RDWR;

        if (flags & O_CREAT) {
                posix_flags |= SMB_O_CREAT;
                if (flags & O_EXCL)
                        posix_flags |= SMB_O_EXCL;
        } else if (flags & O_EXCL)
                cifs_dbg(FYI, "Application %s pid %d has incorrectly set O_EXCL flag but not O_CREAT on file open. Ignoring O_EXCL\n",
                         current->comm, current->tgid);

        if (flags & O_TRUNC)
                posix_flags |= SMB_O_TRUNC;
        /* be safe and imply O_SYNC for O_DSYNC */
        if (flags & O_DSYNC)
                posix_flags |= SMB_O_SYNC;
        if (flags & O_DIRECTORY)
                posix_flags |= SMB_O_DIRECTORY;
        if (flags & O_NOFOLLOW)
                posix_flags |= SMB_O_NOFOLLOW;
        if (flags & O_DIRECT)
                posix_flags |= SMB_O_DIRECT;

        return posix_flags;
}

static inline int cifs_get_disposition(unsigned int flags)
{
        if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
                return FILE_CREATE;
        else if ((flags & (O_CREAT | O_TRUNC)) == (O_CREAT | O_TRUNC))
                return FILE_OVERWRITE_IF;
        else if ((flags & O_CREAT) == O_CREAT)
                return FILE_OPEN_IF;
        else if ((flags & O_TRUNC) == O_TRUNC)
                return FILE_OVERWRITE;
        else
                return FILE_OPEN;
}

int cifs_posix_open(const char *full_path, struct inode **pinode,
                        struct super_block *sb, int mode, unsigned int f_flags,
                        __u32 *poplock, __u16 *pnetfid, unsigned int xid)
{
        int rc;
        FILE_UNIX_BASIC_INFO *presp_data;
        __u32 posix_flags = 0;
        struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
        struct cifs_fattr fattr;
        struct tcon_link *tlink;
        struct cifs_tcon *tcon;

        cifs_dbg(FYI, "posix open %s\n", full_path);

        presp_data = kzalloc(sizeof(FILE_UNIX_BASIC_INFO), GFP_KERNEL);
        if (presp_data == NULL)
                return -ENOMEM;

        tlink = cifs_sb_tlink(cifs_sb);
        if (IS_ERR(tlink)) {
                rc = PTR_ERR(tlink);
                goto posix_open_ret;
        }

        tcon = tlink_tcon(tlink);
        mode &= ~current_umask();

        posix_flags = cifs_posix_convert_flags(f_flags);
        rc = CIFSPOSIXCreate(xid, tcon, posix_flags, mode, pnetfid, presp_data,
                             poplock, full_path, cifs_sb->local_nls,
                             cifs_remap(cifs_sb));
        cifs_put_tlink(tlink);

        if (rc)
                goto posix_open_ret;

        if (presp_data->Type == cpu_to_le32(-1))
                goto posix_open_ret; /* open ok, caller does qpathinfo */

        if (!pinode)
                goto posix_open_ret; /* caller does not need info */

        cifs_unix_basic_to_fattr(&fattr, presp_data, cifs_sb);

        /* get new inode and set it up */
        if (*pinode == NULL) {
                cifs_fill_uniqueid(sb, &fattr);
                *pinode = cifs_iget(sb, &fattr);
                if (!*pinode) {
                        rc = -ENOMEM;
                        goto posix_open_ret;
                }
        } else {
                cifs_revalidate_mapping(*pinode);
                rc = cifs_fattr_to_inode(*pinode, &fattr);
        }

posix_open_ret:
        kfree(presp_data);
        return rc;
}

static int
cifs_nt_open(const char *full_path, struct inode *inode, struct cifs_sb_info *cifs_sb,
             struct cifs_tcon *tcon, unsigned int f_flags, __u32 *oplock,
             struct cifs_fid *fid, unsigned int xid)
{
        int rc;
        int desired_access;
        int disposition;
        int create_options = CREATE_NOT_DIR;
        FILE_ALL_INFO *buf;
        struct TCP_Server_Info *server = tcon->ses->server;
        struct cifs_open_parms oparms;

        if (!server->ops->open)
                return -ENOSYS;

        desired_access = cifs_convert_flags(f_flags);

/*********************************************************************
 *  open flag mapping table:
 *
 *      POSIX Flag            CIFS Disposition
 *      ----------            ----------------
 *      O_CREAT               FILE_OPEN_IF
 *      O_CREAT | O_EXCL      FILE_CREATE
 *      O_CREAT | O_TRUNC     FILE_OVERWRITE_IF
 *      O_TRUNC               FILE_OVERWRITE
 *      none of the above     FILE_OPEN
 *
 *      Note that there is not a direct match between disposition
 *      FILE_SUPERSEDE (ie create whether or not file exists although
 *      O_CREAT | O_TRUNC is similar but truncates the existing
 *      file rather than creating a new file as FILE_SUPERSEDE does
 *      (which uses the attributes / metadata passed in on open call)
 *?
 *?  O_SYNC is a reasonable match to CIFS writethrough flag
 *?  and the read write flags match reasonably.  O_LARGEFILE
 *?  is irrelevant because largefile support is always used
 *?  by this client. Flags O_APPEND, O_DIRECT, O_DIRECTORY,
 *       O_FASYNC, O_NOFOLLOW, O_NONBLOCK need further investigation
 *********************************************************************/

        disposition = cifs_get_disposition(f_flags);

        /* BB pass O_SYNC flag through on file attributes .. BB */

        buf = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        /* O_SYNC also has bit for O_DSYNC so following check picks up either */
        if (f_flags & O_SYNC)
                create_options |= CREATE_WRITE_THROUGH;

        if (f_flags & O_DIRECT)
                create_options |= CREATE_NO_BUFFER;

        oparms.tcon = tcon;
        oparms.cifs_sb = cifs_sb;
        oparms.desired_access = desired_access;
        oparms.create_options = cifs_create_options(cifs_sb, create_options);
        oparms.disposition = disposition;
        oparms.path = full_path;
        oparms.fid = fid;
        oparms.reconnect = false;

        rc = server->ops->open(xid, &oparms, oplock, buf);

        if (rc)
                goto out;

        /* TODO: Add support for calling posix query info but with passing in fid */
        if (tcon->unix_ext)
                rc = cifs_get_inode_info_unix(&inode, full_path, inode->i_sb,
                                              xid);
        else
                rc = cifs_get_inode_info(&inode, full_path, buf, inode->i_sb,
                                         xid, fid);

        if (rc) {
                server->ops->close(xid, tcon, fid);
                if (rc == -ESTALE)
                        rc = -EOPENSTALE;
        }

out:
        kfree(buf);
        return rc;
}

static bool
cifs_has_mand_locks(struct cifsInodeInfo *cinode)
{
        struct cifs_fid_locks *cur;
        bool has_locks = false;

        down_read(&cinode->lock_sem);
        list_for_each_entry(cur, &cinode->llist, llist) {
                if (!list_empty(&cur->locks)) {
                        has_locks = true;
                        break;
                }
        }
        up_read(&cinode->lock_sem);
        return has_locks;
}

void
cifs_down_write(struct rw_semaphore *sem)
{
        while (!down_write_trylock(sem))
                msleep(10);
}

static void cifsFileInfo_put_work(struct work_struct *work);

struct cifsFileInfo *
cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
                  struct tcon_link *tlink, __u32 oplock)
{
        struct dentry *dentry = file_dentry(file);
        struct inode *inode = d_inode(dentry);
        struct cifsInodeInfo *cinode = CIFS_I(inode);
        struct cifsFileInfo *cfile;
        struct cifs_fid_locks *fdlocks;
        struct cifs_tcon *tcon = tlink_tcon(tlink);
        struct TCP_Server_Info *server = tcon->ses->server;

        cfile = kzalloc(sizeof(struct cifsFileInfo), GFP_KERNEL);
        if (cfile == NULL)
                return cfile;

        fdlocks = kzalloc(sizeof(struct cifs_fid_locks), GFP_KERNEL);
        if (!fdlocks) {
                kfree(cfile);
                return NULL;
        }

        INIT_LIST_HEAD(&fdlocks->locks);
        fdlocks->cfile = cfile;
        cfile->llist = fdlocks;

        cfile->count = 1;
        cfile->pid = current->tgid;
        cfile->uid = current_fsuid();
        cfile->dentry = dget(dentry);
        cfile->f_flags = file->f_flags;
        cfile->invalidHandle = false;
        cfile->deferred_close_scheduled = false;
        cfile->tlink = cifs_get_tlink(tlink);
        INIT_WORK(&cfile->oplock_break, cifs_oplock_break);
        INIT_WORK(&cfile->put, cifsFileInfo_put_work);
        INIT_DELAYED_WORK(&cfile->deferred, smb2_deferred_work_close);
        mutex_init(&cfile->fh_mutex);
        spin_lock_init(&cfile->file_info_lock);

        cifs_sb_active(inode->i_sb);

        /*
         * If the server returned a read oplock and we have mandatory brlocks,
         * set oplock level to None.
         */
        if (server->ops->is_read_op(oplock) && cifs_has_mand_locks(cinode)) {
                cifs_dbg(FYI, "Reset oplock val from read to None due to mand locks\n");
                oplock = 0;
        }

        cifs_down_write(&cinode->lock_sem);
        list_add(&fdlocks->llist, &cinode->llist);
        up_write(&cinode->lock_sem);

        spin_lock(&tcon->open_file_lock);
        if (fid->pending_open->oplock != CIFS_OPLOCK_NO_CHANGE && oplock)
                oplock = fid->pending_open->oplock;
        list_del(&fid->pending_open->olist);

        fid->purge_cache = false;
        server->ops->set_fid(cfile, fid, oplock);

        list_add(&cfile->tlist, &tcon->openFileList);
        atomic_inc(&tcon->num_local_opens);

        /* if readable file instance put first in list*/
        spin_lock(&cinode->open_file_lock);
        if (file->f_mode & FMODE_READ)
                list_add(&cfile->flist, &cinode->openFileList);
        else
                list_add_tail(&cfile->flist, &cinode->openFileList);
        spin_unlock(&cinode->open_file_lock);
        spin_unlock(&tcon->open_file_lock);

        if (fid->purge_cache)
                cifs_zap_mapping(inode);

        file->private_data = cfile;
        return cfile;
}

struct cifsFileInfo *
cifsFileInfo_get(struct cifsFileInfo *cifs_file)
{
        spin_lock(&cifs_file->file_info_lock);
        cifsFileInfo_get_locked(cifs_file);
        spin_unlock(&cifs_file->file_info_lock);
        return cifs_file;
}

static void cifsFileInfo_put_final(struct cifsFileInfo *cifs_file)
{
        struct inode *inode = d_inode(cifs_file->dentry);
        struct cifsInodeInfo *cifsi = CIFS_I(inode);
        struct cifsLockInfo *li, *tmp;
        struct super_block *sb = inode->i_sb;

        cifs_fscache_release_inode_cookie(inode);

        /*
         * Delete any outstanding lock records. We'll lose them when the file
         * is closed anyway.
         */
        cifs_down_write(&cifsi->lock_sem);
        list_for_each_entry_safe(li, tmp, &cifs_file->llist->locks, llist) {
                list_del(&li->llist);
                cifs_del_lock_waiters(li);
                kfree(li);
        }
        list_del(&cifs_file->llist->llist);
        kfree(cifs_file->llist);
        up_write(&cifsi->lock_sem);

        cifs_put_tlink(cifs_file->tlink);
        dput(cifs_file->dentry);
        cifs_sb_deactive(sb);
        kfree(cifs_file);
}

static void cifsFileInfo_put_work(struct work_struct *work)
{
        struct cifsFileInfo *cifs_file = container_of(work,
                        struct cifsFileInfo, put);

        cifsFileInfo_put_final(cifs_file);
}

/**
 * cifsFileInfo_put - release a reference of file priv data
 *
 * Always potentially wait for oplock handler. See _cifsFileInfo_put().
 *
 * @cifs_file:  cifs/smb3 specific info (eg refcounts) for an open file
 */
void cifsFileInfo_put(struct cifsFileInfo *cifs_file)
{
        _cifsFileInfo_put(cifs_file, true, true);
}

/**
 * _cifsFileInfo_put - release a reference of file priv data
 *
 * This may involve closing the filehandle @cifs_file out on the
 * server. Must be called without holding tcon->open_file_lock,
 * cinode->open_file_lock and cifs_file->file_info_lock.
 *
 * If @wait_for_oplock_handler is true and we are releasing the last
 * reference, wait for any running oplock break handler of the file
 * and cancel any pending one.
 *
 * @cifs_file:  cifs/smb3 specific info (eg refcounts) for an open file
 * @wait_oplock_handler: must be false if called from oplock_break_handler
 * @offload:    not offloaded on close and oplock breaks
 *
 */
void _cifsFileInfo_put(struct cifsFileInfo *cifs_file,
                       bool wait_oplock_handler, bool offload)
{
        struct inode *inode = d_inode(cifs_file->dentry);
        struct cifs_tcon *tcon = tlink_tcon(cifs_file->tlink);
        struct TCP_Server_Info *server = tcon->ses->server;
        struct cifsInodeInfo *cifsi = CIFS_I(inode);
        struct super_block *sb = inode->i_sb;
        struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
        struct cifs_fid fid;
        struct cifs_pending_open open;
        bool oplock_break_cancelled;

        spin_lock(&tcon->open_file_lock);
        spin_lock(&cifsi->open_file_lock);
        spin_lock(&cifs_file->file_info_lock);
        if (--cifs_file->count > 0) {
                spin_unlock(&cifs_file->file_info_lock);
                spin_unlock(&cifsi->open_file_lock);
                spin_unlock(&tcon->open_file_lock);
                return;
        }
        spin_unlock(&cifs_file->file_info_lock);

        if (server->ops->get_lease_key)
                server->ops->get_lease_key(inode, &fid);

        /* store open in pending opens to make sure we don't miss lease break */
        cifs_add_pending_open_locked(&fid, cifs_file->tlink, &open);

        /* remove it from the lists */
        list_del(&cifs_file->flist);
        list_del(&cifs_file->tlist);
        atomic_dec(&tcon->num_local_opens);

        if (list_empty(&cifsi->openFileList)) {
                cifs_dbg(FYI, "closing last open instance for inode %p\n",
                         d_inode(cifs_file->dentry));
                /*
                 * In strict cache mode we need invalidate mapping on the last
                 * close  because it may cause a error when we open this file
                 * again and get at least level II oplock.
                 */
                if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO)
                        set_bit(CIFS_INO_INVALID_MAPPING, &cifsi->flags);
                cifs_set_oplock_level(cifsi, 0);
        }

        spin_unlock(&cifsi->open_file_lock);
        spin_unlock(&tcon->open_file_lock);

        oplock_break_cancelled = wait_oplock_handler ?
                cancel_work_sync(&cifs_file->oplock_break) : false;

        if (!tcon->need_reconnect && !cifs_file->invalidHandle) {
                struct TCP_Server_Info *server = tcon->ses->server;
                unsigned int xid;

                xid = get_xid();
                if (server->ops->close_getattr)
                        server->ops->close_getattr(xid, tcon, cifs_file);
                else if (server->ops->close)
                        server->ops->close(xid, tcon, &cifs_file->fid);
                _free_xid(xid);
        }

        if (oplock_break_cancelled)
                cifs_done_oplock_break(cifsi);

        cifs_del_pending_open(&open);

        if (offload)
                queue_work(fileinfo_put_wq, &cifs_file->put);
        else
                cifsFileInfo_put_final(cifs_file);
}

int cifs_open(struct inode *inode, struct file *file)

{
        int rc = -EACCES;
        unsigned int xid;
        __u32 oplock;
        struct cifs_sb_info *cifs_sb;
        struct TCP_Server_Info *server;
        struct cifs_tcon *tcon;
        struct tcon_link *tlink;
        struct cifsFileInfo *cfile = NULL;
        void *page;
        const char *full_path;
        bool posix_open_ok = false;
        struct cifs_fid fid;
        struct cifs_pending_open open;

        xid = get_xid();

        cifs_sb = CIFS_SB(inode->i_sb);
        if (unlikely(cifs_forced_shutdown(cifs_sb))) {
                free_xid(xid);
                return -EIO;
        }

        tlink = cifs_sb_tlink(cifs_sb);
        if (IS_ERR(tlink)) {
                free_xid(xid);
                return PTR_ERR(tlink);
        }
        tcon = tlink_tcon(tlink);
        server = tcon->ses->server;

        page = alloc_dentry_path();
        full_path = build_path_from_dentry(file_dentry(file), page);
        if (IS_ERR(full_path)) {
                rc = PTR_ERR(full_path);
                goto out;
        }

        cifs_dbg(FYI, "inode = 0x%p file flags are 0x%x for %s\n",
                 inode, file->f_flags, full_path);

        if (file->f_flags & O_DIRECT &&
            cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO) {
                if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_BRL)
                        file->f_op = &cifs_file_direct_nobrl_ops;
                else
                        file->f_op = &cifs_file_direct_ops;
        }

        /* Get the cached handle as SMB2 close is deferred */
        rc = cifs_get_readable_path(tcon, full_path, &cfile);
        if (rc == 0) {
                if (file->f_flags == cfile->f_flags) {
                        file->private_data = cfile;
                        spin_lock(&CIFS_I(inode)->deferred_lock);
                        cifs_del_deferred_close(cfile);
                        spin_unlock(&CIFS_I(inode)->deferred_lock);
                        goto out;
                } else {
                        _cifsFileInfo_put(cfile, true, false);
                }
        }

        if (server->oplocks)
                oplock = REQ_OPLOCK;
        else
                oplock = 0;

        if (!tcon->broken_posix_open && tcon->unix_ext &&
            cap_unix(tcon->ses) && (CIFS_UNIX_POSIX_PATH_OPS_CAP &
                                le64_to_cpu(tcon->fsUnixInfo.Capability))) {
                /* can not refresh inode info since size could be stale */
                rc = cifs_posix_open(full_path, &inode, inode->i_sb,
                                cifs_sb->ctx->file_mode /* ignored */,
                                file->f_flags, &oplock, &fid.netfid, xid);
                if (rc == 0) {
                        cifs_dbg(FYI, "posix open succeeded\n");
                        posix_open_ok = true;
                } else if ((rc == -EINVAL) || (rc == -EOPNOTSUPP)) {
                        if (tcon->ses->serverNOS)
                                cifs_dbg(VFS, "server %s of type %s returned unexpected error on SMB posix open, disabling posix open support. Check if server update available.\n",
                                         tcon->ses->ip_addr,
                                         tcon->ses->serverNOS);
                        tcon->broken_posix_open = true;
                } else if ((rc != -EIO) && (rc != -EREMOTE) &&
                         (rc != -EOPNOTSUPP)) /* path not found or net err */
                        goto out;
                /*
                 * Else fallthrough to retry open the old way on network i/o
                 * or DFS errors.
                 */
        }

        if (server->ops->get_lease_key)
                server->ops->get_lease_key(inode, &fid);

        cifs_add_pending_open(&fid, tlink, &open);

        if (!posix_open_ok) {
                if (server->ops->get_lease_key)
                        server->ops->get_lease_key(inode, &fid);

                rc = cifs_nt_open(full_path, inode, cifs_sb, tcon,
                                  file->f_flags, &oplock, &fid, xid);
                if (rc) {
                        cifs_del_pending_open(&open);
                        goto out;
                }
        }

        cfile = cifs_new_fileinfo(&fid, file, tlink, oplock);
        if (cfile == NULL) {
                if (server->ops->close)
                        server->ops->close(xid, tcon, &fid);
                cifs_del_pending_open(&open);
                rc = -ENOMEM;
                goto out;
        }

        cifs_fscache_set_inode_cookie(inode, file);

        if ((oplock & CIFS_CREATE_ACTION) && !posix_open_ok && tcon->unix_ext) {
                /*
                 * Time to set mode which we can not set earlier due to
                 * problems creating new read-only files.
                 */
                struct cifs_unix_set_info_args args = {
                        .mode   = inode->i_mode,
                        .uid    = INVALID_UID, /* no change */
                        .gid    = INVALID_GID, /* no change */
                        .ctime  = NO_CHANGE_64,
                        .atime  = NO_CHANGE_64,
                        .mtime  = NO_CHANGE_64,
                        .device = 0,
                };
                CIFSSMBUnixSetFileInfo(xid, tcon, &args, fid.netfid,
                                       cfile->pid);
        }

out:
        free_dentry_path(page);
        free_xid(xid);
        cifs_put_tlink(tlink);
        return rc;
}

static int cifs_push_posix_locks(struct cifsFileInfo *cfile);

/*
 * Try to reacquire byte range locks that were released when session
 * to server was lost.
 */
static int
cifs_relock_file(struct cifsFileInfo *cfile)
{
        struct cifs_sb_info *cifs_sb = CIFS_SB(cfile->dentry->d_sb);
        struct cifsInodeInfo *cinode = CIFS_I(d_inode(cfile->dentry));
        struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
        int rc = 0;

        down_read_nested(&cinode->lock_sem, SINGLE_DEPTH_NESTING);
        if (cinode->can_cache_brlcks) {
                /* can cache locks - no need to relock */
                up_read(&cinode->lock_sem);
                return rc;
        }

        if (cap_unix(tcon->ses) &&
            (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
            ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
                rc = cifs_push_posix_locks(cfile);
        else
                rc = tcon->ses->server->ops->push_mand_locks(cfile);

        up_read(&cinode->lock_sem);
        return rc;
}

static int
cifs_reopen_file(struct cifsFileInfo *cfile, bool can_flush)
{
        int rc = -EACCES;
        unsigned int xid;
        __u32 oplock;
        struct cifs_sb_info *cifs_sb;
        struct cifs_tcon *tcon;
        struct TCP_Server_Info *server;
        struct cifsInodeInfo *cinode;
        struct inode *inode;
        void *page;
        const char *full_path;
        int desired_access;
        int disposition = FILE_OPEN;
        int create_options = CREATE_NOT_DIR;
        struct cifs_open_parms oparms;

        xid = get_xid();
        mutex_lock(&cfile->fh_mutex);
        if (!cfile->invalidHandle) {
                mutex_unlock(&cfile->fh_mutex);
                free_xid(xid);
                return 0;
        }

        inode = d_inode(cfile->dentry);
        cifs_sb = CIFS_SB(inode->i_sb);
        tcon = tlink_tcon(cfile->tlink);
        server = tcon->ses->server;

        /*
         * Can not grab rename sem here because various ops, including those
         * that already have the rename sem can end up causing writepage to get
         * called and if the server was down that means we end up here, and we
         * can never tell if the caller already has the rename_sem.
         */
        page = alloc_dentry_path();
        full_path = build_path_from_dentry(cfile->dentry, page);
        if (IS_ERR(full_path)) {
                mutex_unlock(&cfile->fh_mutex);
                free_dentry_path(page);
                free_xid(xid);
                return PTR_ERR(full_path);
        }

        cifs_dbg(FYI, "inode = 0x%p file flags 0x%x for %s\n",
                 inode, cfile->f_flags, full_path);

        if (tcon->ses->server->oplocks)
                oplock = REQ_OPLOCK;
        else
                oplock = 0;

        if (tcon->unix_ext && cap_unix(tcon->ses) &&
            (CIFS_UNIX_POSIX_PATH_OPS_CAP &
                                le64_to_cpu(tcon->fsUnixInfo.Capability))) {
                /*
                 * O_CREAT, O_EXCL and O_TRUNC already had their effect on the
                 * original open. Must mask them off for a reopen.
                 */
                unsigned int oflags = cfile->f_flags &
                                                ~(O_CREAT | O_EXCL | O_TRUNC);

                rc = cifs_posix_open(full_path, NULL, inode->i_sb,
                                     cifs_sb->ctx->file_mode /* ignored */,
                                     oflags, &oplock, &cfile->fid.netfid, xid);
                if (rc == 0) {
                        cifs_dbg(FYI, "posix reopen succeeded\n");
                        oparms.reconnect = true;
                        goto reopen_success;
                }
                /*
                 * fallthrough to retry open the old way on errors, especially
                 * in the reconnect path it is important to retry hard
                 */
        }

        desired_access = cifs_convert_flags(cfile->f_flags);

        /* O_SYNC also has bit for O_DSYNC so following check picks up either */
        if (cfile->f_flags & O_SYNC)
                create_options |= CREATE_WRITE_THROUGH;

        if (cfile->f_flags & O_DIRECT)
                create_options |= CREATE_NO_BUFFER;

        if (server->ops->get_lease_key)
                server->ops->get_lease_key(inode, &cfile->fid);

        oparms.tcon = tcon;
        oparms.cifs_sb = cifs_sb;
        oparms.desired_access = desired_access;
        oparms.create_options = cifs_create_options(cifs_sb, create_options);
        oparms.disposition = disposition;
        oparms.path = full_path;
        oparms.fid = &cfile->fid;
        oparms.reconnect = true;

        /*
         * Can not refresh inode by passing in file_info buf to be returned by
         * ops->open and then calling get_inode_info with returned buf since
         * file might have write behind data that needs to be flushed and server
         * version of file size can be stale. If we knew for sure that inode was
         * not dirty locally we could do this.
         */
        rc = server->ops->open(xid, &oparms, &oplock, NULL);
        if (rc == -ENOENT && oparms.reconnect == false) {
                /* durable handle timeout is expired - open the file again */
                rc = server->ops->open(xid, &oparms, &oplock, NULL);
                /* indicate that we need to relock the file */
                oparms.reconnect = true;
        }

        if (rc) {
                mutex_unlock(&cfile->fh_mutex);
                cifs_dbg(FYI, "cifs_reopen returned 0x%x\n", rc);
                cifs_dbg(FYI, "oplock: %d\n", oplock);
                goto reopen_error_exit;
        }

reopen_success:
        cfile->invalidHandle = false;
        mutex_unlock(&cfile->fh_mutex);
        cinode = CIFS_I(inode);

        if (can_flush) {
                rc = filemap_write_and_wait(inode->i_mapping);
                if (!is_interrupt_error(rc))
                        mapping_set_error(inode->i_mapping, rc);

                if (tcon->posix_extensions)
                        rc = smb311_posix_get_inode_info(&inode, full_path, inode->i_sb, xid);
                else if (tcon->unix_ext)
                        rc = cifs_get_inode_info_unix(&inode, full_path,
                                                      inode->i_sb, xid);
                else
                        rc = cifs_get_inode_info(&inode, full_path, NULL,
                                                 inode->i_sb, xid, NULL);
        }
        /*
         * Else we are writing out data to server already and could deadlock if
         * we tried to flush data, and since we do not know if we have data that
         * would invalidate the current end of file on the server we can not go
         * to the server to get the new inode info.
         */

        /*
         * If the server returned a read oplock and we have mandatory brlocks,
         * set oplock level to None.
         */
        if (server->ops->is_read_op(oplock) && cifs_has_mand_locks(cinode)) {
                cifs_dbg(FYI, "Reset oplock val from read to None due to mand locks\n");
                oplock = 0;
        }

        server->ops->set_fid(cfile, &cfile->fid, oplock);
        if (oparms.reconnect)
                cifs_relock_file(cfile);

reopen_error_exit:
        free_dentry_path(page);
        free_xid(xid);
        return rc;
}

void smb2_deferred_work_close(struct work_struct *work)
{
        struct cifsFileInfo *cfile = container_of(work,
                        struct cifsFileInfo, deferred.work);

        spin_lock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
        cifs_del_deferred_close(cfile);
        cfile->deferred_close_scheduled = false;
        spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
        _cifsFileInfo_put(cfile, true, false);
}

int cifs_close(struct inode *inode, struct file *file)
{
        struct cifsFileInfo *cfile;
        struct cifsInodeInfo *cinode = CIFS_I(inode);
        struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
        struct cifs_deferred_close *dclose;

        if (file->private_data != NULL) {
                cfile = file->private_data;
                file->private_data = NULL;
                dclose = kmalloc(sizeof(struct cifs_deferred_close), GFP_KERNEL);
                if ((cinode->oplock == CIFS_CACHE_RHW_FLG) &&
                    cinode->lease_granted &&
                    !test_bit(CIFS_INO_CLOSE_ON_LOCK, &cinode->flags) &&
                    dclose) {
                        if (test_and_clear_bit(CIFS_INO_MODIFIED_ATTR, &cinode->flags)) {
                                inode->i_ctime = inode->i_mtime = current_time(inode);
                                cifs_fscache_update_inode_cookie(inode);
                        }
                        spin_lock(&cinode->deferred_lock);
                        cifs_add_deferred_close(cfile, dclose);
                        if (cfile->deferred_close_scheduled &&
                            delayed_work_pending(&cfile->deferred)) {
                                /*
                                 * If there is no pending work, mod_delayed_work queues new work.
                                 * So, Increase the ref count to avoid use-after-free.
                                 */
                                if (!mod_delayed_work(deferredclose_wq,
                                                &cfile->deferred, cifs_sb->ctx->acregmax))
                                        cifsFileInfo_get(cfile);
                        } else {
                                /* Deferred close for files */
                                queue_delayed_work(deferredclose_wq,
                                                &cfile->deferred, cifs_sb->ctx->acregmax);
                                cfile->deferred_close_scheduled = true;
                                spin_unlock(&cinode->deferred_lock);
                                return 0;
                        }
                        spin_unlock(&cinode->deferred_lock);
                        _cifsFileInfo_put(cfile, true, false);
                } else {
                        _cifsFileInfo_put(cfile, true, false);
                        kfree(dclose);
                }
        }

        /* return code from the ->release op is always ignored */
        return 0;
}

void
cifs_reopen_persistent_handles(struct cifs_tcon *tcon)
{
        struct cifsFileInfo *open_file;
        struct list_head *tmp;
        struct list_head *tmp1;
        struct list_head tmp_list;

        if (!tcon->use_persistent || !tcon->need_reopen_files)
                return;

        tcon->need_reopen_files = false;

        cifs_dbg(FYI, "Reopen persistent handles\n");
        INIT_LIST_HEAD(&tmp_list);

        /* list all files open on tree connection, reopen resilient handles  */
        spin_lock(&tcon->open_file_lock);
        list_for_each(tmp, &tcon->openFileList) {
                open_file = list_entry(tmp, struct cifsFileInfo, tlist);
                if (!open_file->invalidHandle)
                        continue;
                cifsFileInfo_get(open_file);
                list_add_tail(&open_file->rlist, &tmp_list);
        }
        spin_unlock(&tcon->open_file_lock);

        list_for_each_safe(tmp, tmp1, &tmp_list) {
                open_file = list_entry(tmp, struct cifsFileInfo, rlist);
                if (cifs_reopen_file(open_file, false /* do not flush */))
                        tcon->need_reopen_files = true;
                list_del_init(&open_file->rlist);
                cifsFileInfo_put(open_file);
        }
}

int cifs_closedir(struct inode *inode, struct file *file)
{
        int rc = 0;
        unsigned int xid;
        struct cifsFileInfo *cfile = file->private_data;
        struct cifs_tcon *tcon;
        struct TCP_Server_Info *server;
        char *buf;

        cifs_dbg(FYI, "Closedir inode = 0x%p\n", inode);

        if (cfile == NULL)
                return rc;

        xid = get_xid();
        tcon = tlink_tcon(cfile->tlink);
        server = tcon->ses->server;

        cifs_dbg(FYI, "Freeing private data in close dir\n");
        spin_lock(&cfile->file_info_lock);
        if (server->ops->dir_needs_close(cfile)) {
                cfile->invalidHandle = true;
                spin_unlock(&cfile->file_info_lock);
                if (server->ops->close_dir)
                        rc = server->ops->close_dir(xid, tcon, &cfile->fid);
                else
                        rc = -ENOSYS;
                cifs_dbg(FYI, "Closing uncompleted readdir with rc %d\n", rc);
                /* not much we can do if it fails anyway, ignore rc */
                rc = 0;
        } else
                spin_unlock(&cfile->file_info_lock);

        buf = cfile->srch_inf.ntwrk_buf_start;
        if (buf) {
                cifs_dbg(FYI, "closedir free smb buf in srch struct\n");
                cfile->srch_inf.ntwrk_buf_start = NULL;
                if (cfile->srch_inf.smallBuf)
                        cifs_small_buf_release(buf);
                else
                        cifs_buf_release(buf);
        }

        cifs_put_tlink(cfile->tlink);
        kfree(file->private_data);
        file->private_data = NULL;
        /* BB can we lock the filestruct while this is going on? */
        free_xid(xid);
        return rc;
}

static struct cifsLockInfo *
cifs_lock_init(__u64 offset, __u64 length, __u8 type, __u16 flags)
{
        struct cifsLockInfo *lock =
                kmalloc(sizeof(struct cifsLockInfo), GFP_KERNEL);
        if (!lock)
                return lock;
        lock->offset = offset;
        lock->length = length;
        lock->type = type;
        lock->pid = current->tgid;
        lock->flags = flags;
        INIT_LIST_HEAD(&lock->blist);
        init_waitqueue_head(&lock->block_q);
        return lock;
}

void
cifs_del_lock_waiters(struct cifsLockInfo *lock)
{
        struct cifsLockInfo *li, *tmp;
        list_for_each_entry_safe(li, tmp, &lock->blist, blist) {
                list_del_init(&li->blist);
                wake_up(&li->block_q);
        }
}

#define CIFS_LOCK_OP    0
#define CIFS_READ_OP    1
#define CIFS_WRITE_OP   2

/* @rw_check : 0 - no op, 1 - read, 2 - write */
static bool
cifs_find_fid_lock_conflict(struct cifs_fid_locks *fdlocks, __u64 offset,
                            __u64 length, __u8 type, __u16 flags,
                            struct cifsFileInfo *cfile,
                            struct cifsLockInfo **conf_lock, int rw_check)
{
        struct cifsLockInfo *li;
        struct cifsFileInfo *cur_cfile = fdlocks->cfile;
        struct TCP_Server_Info *server = tlink_tcon(cfile->tlink)->ses->server;

        list_for_each_entry(li, &fdlocks->locks, llist) {
                if (offset + length <= li->offset ||
                    offset >= li->offset + li->length)
                        continue;
                if (rw_check != CIFS_LOCK_OP && current->tgid == li->pid &&
                    server->ops->compare_fids(cfile, cur_cfile)) {
                        /* shared lock prevents write op through the same fid */
                        if (!(li->type & server->vals->shared_lock_type) ||
                            rw_check != CIFS_WRITE_OP)
                                continue;
                }
                if ((type & server->vals->shared_lock_type) &&
                    ((server->ops->compare_fids(cfile, cur_cfile) &&
                     current->tgid == li->pid) || type == li->type))
                        continue;
                if (rw_check == CIFS_LOCK_OP &&
                    (flags & FL_OFDLCK) && (li->flags & FL_OFDLCK) &&
                    server->ops->compare_fids(cfile, cur_cfile))
                        continue;
                if (conf_lock)
                        *conf_lock = li;
                return true;
        }
        return false;
}

bool
cifs_find_lock_conflict(struct cifsFileInfo *cfile, __u64 offset, __u64 length,
                        __u8 type, __u16 flags,
                        struct cifsLockInfo **conf_lock, int rw_check)
{
        bool rc = false;
        struct cifs_fid_locks *cur;
        struct cifsInodeInfo *cinode = CIFS_I(d_inode(cfile->dentry));

        list_for_each_entry(cur, &cinode->llist, llist) {
                rc = cifs_find_fid_lock_conflict(cur, offset, length, type,
                                                 flags, cfile, conf_lock,
                                                 rw_check);
                if (rc)
                        break;
        }

        return rc;
}

/*
 * Check if there is another lock that prevents us to set the lock (mandatory
 * style). If such a lock exists, update the flock structure with its
 * properties. Otherwise, set the flock type to F_UNLCK if we can cache brlocks
 * or leave it the same if we can't. Returns 0 if we don't need to request to
 * the server or 1 otherwise.
 */
static int
cifs_lock_test(struct cifsFileInfo *cfile, __u64 offset, __u64 length,
               __u8 type, struct file_lock *flock)
{
        int rc = 0;
        struct cifsLockInfo *conf_lock;
        struct cifsInodeInfo *cinode = CIFS_I(d_inode(cfile->dentry));
        struct TCP_Server_Info *server = tlink_tcon(cfile->tlink)->ses->server;
        bool exist;

        down_read(&cinode->lock_sem);

        exist = cifs_find_lock_conflict(cfile, offset, length, type,
                                        flock->fl_flags, &conf_lock,
                                        CIFS_LOCK_OP);
        if (exist) {
                flock->fl_start = conf_lock->offset;
                flock->fl_end = conf_lock->offset + conf_lock->length - 1;
                flock->fl_pid = conf_lock->pid;
                if (conf_lock->type & server->vals->shared_lock_type)
                        flock->fl_type = F_RDLCK;
                else
                        flock->fl_type = F_WRLCK;
        } else if (!cinode->can_cache_brlcks)
                rc = 1;
        else
                flock->fl_type = F_UNLCK;

        up_read(&cinode->lock_sem);
        return rc;
}

static void
cifs_lock_add(struct cifsFileInfo *cfile, struct cifsLockInfo *lock)
{
        struct cifsInodeInfo *cinode = CIFS_I(d_inode(cfile->dentry));
        cifs_down_write(&cinode->lock_sem);
        list_add_tail(&lock->llist, &cfile->llist->locks);
        up_write(&cinode->lock_sem);
}

/*
 * Set the byte-range lock (mandatory style). Returns:
 * 1) 0, if we set the lock and don't need to request to the server;
 * 2) 1, if no locks prevent us but we need to request to the server;
 * 3) -EACCES, if there is a lock that prevents us and wait is false.
 */
static int
cifs_lock_add_if(struct cifsFileInfo *cfile, struct cifsLockInfo *lock,
                 bool wait)
{
        struct cifsLockInfo *conf_lock;
        struct cifsInodeInfo *cinode = CIFS_I(d_inode(cfile->dentry));
        bool exist;
        int rc = 0;

try_again:
        exist = false;
        cifs_down_write(&cinode->lock_sem);

        exist = cifs_find_lock_conflict(cfile, lock->offset, lock->length,
                                        lock->type, lock->flags, &conf_lock,
                                        CIFS_LOCK_OP);
        if (!exist && cinode->can_cache_brlcks) {
                list_add_tail(&lock->llist, &cfile->llist->locks);
                up_write(&cinode->lock_sem);
                return rc;
        }

        if (!exist)
                rc = 1;
        else if (!wait)
                rc = -EACCES;
        else {
                list_add_tail(&lock->blist, &conf_lock->blist);
                up_write(&cinode->lock_sem);
                rc = wait_event_interruptible(lock->block_q,
                                        (lock->blist.prev == &lock->blist) &&
                                        (lock->blist.next == &lock->blist));
                if (!rc)
                        goto try_again;
                cifs_down_write(&cinode->lock_sem);
                list_del_init(&lock->blist);
        }

        up_write(&cinode->lock_sem);
        return rc;
}

/*
 * Check if there is another lock that prevents us to set the lock (posix
 * style). If such a lock exists, update the flock structure with its
 * properties. Otherwise, set the flock type to F_UNLCK if we can cache brlocks
 * or leave it the same if we can't. Returns 0 if we don't need to request to
 * the server or 1 otherwise.
 */
static int
cifs_posix_lock_test(struct file *file, struct file_lock *flock)
{
        int rc = 0;
        struct cifsInodeInfo *cinode = CIFS_I(file_inode(file));
        unsigned char saved_type = flock->fl_type;

        if ((flock->fl_flags & FL_POSIX) == 0)
                return 1;

        down_read(&cinode->lock_sem);
        posix_test_lock(file, flock);

        if (flock->fl_type == F_UNLCK && !cinode->can_cache_brlcks) {
                flock->fl_type = saved_type;
                rc = 1;
        }

        up_read(&cinode->lock_sem);
        return rc;
}

/*
 * Set the byte-range lock (posix style). Returns:
 * 1) <0, if the error occurs while setting the lock;
 * 2) 0, if we set the lock and don't need to request to the server;
 * 3) FILE_LOCK_DEFERRED, if we will wait for some other file_lock;
 * 4) FILE_LOCK_DEFERRED + 1, if we need to request to the server.
 */
static int
cifs_posix_lock_set(struct file *file, struct file_lock *flock)
{
        struct cifsInodeInfo *cinode = CIFS_I(file_inode(file));
        int rc = FILE_LOCK_DEFERRED + 1;

        if ((flock->fl_flags & FL_POSIX) == 0)
                return rc;

        cifs_down_write(&cinode->lock_sem);
        if (!cinode->can_cache_brlcks) {
                up_write(&cinode->lock_sem);
                return rc;
        }

        rc = posix_lock_file(file, flock, NULL);
        up_write(&cinode->lock_sem);
        return rc;
}

int
cifs_push_mandatory_locks(struct cifsFileInfo *cfile)
{
        unsigned int xid;
        int rc = 0, stored_rc;
        struct cifsLockInfo *li, *tmp;
        struct cifs_tcon *tcon;
        unsigned int num, max_num, max_buf;
        LOCKING_ANDX_RANGE *buf, *cur;
        static const int types[] = {
                LOCKING_ANDX_LARGE_FILES,
                LOCKING_ANDX_SHARED_LOCK | LOCKING_ANDX_LARGE_FILES
        };
        int i;

        xid = get_xid();
        tcon = tlink_tcon(cfile->tlink);

        /*
         * Accessing maxBuf is racy with cifs_reconnect - need to store value
         * and check it before using.
         */
        max_buf = tcon->ses->server->maxBuf;
        if (max_buf < (sizeof(struct smb_hdr) + sizeof(LOCKING_ANDX_RANGE))) {
                free_xid(xid);
                return -EINVAL;
        }

        BUILD_BUG_ON(sizeof(struct smb_hdr) + sizeof(LOCKING_ANDX_RANGE) >
                     PAGE_SIZE);
        max_buf = min_t(unsigned int, max_buf - sizeof(struct smb_hdr),
                        PAGE_SIZE);
        max_num = (max_buf - sizeof(struct smb_hdr)) /
                                                sizeof(LOCKING_ANDX_RANGE);
        buf = kcalloc(max_num, sizeof(LOCKING_ANDX_RANGE), GFP_KERNEL);
        if (!buf) {
                free_xid(xid);
                return -ENOMEM;
        }

        for (i = 0; i < 2; i++) {
                cur = buf;
                num = 0;
                list_for_each_entry_safe(li, tmp, &cfile->llist->locks, llist) {
                        if (li->type != types[i])
                                continue;
                        cur->Pid = cpu_to_le16(li->pid);
                        cur->LengthLow = cpu_to_le32((u32)li->length);
                        cur->LengthHigh = cpu_to_le32((u32)(li->length>>32));
                        cur->OffsetLow = cpu_to_le32((u32)li->offset);
                        cur->OffsetHigh = cpu_to_le32((u32)(li->offset>>32));
                        if (++num == max_num) {
                                stored_rc = cifs_lockv(xid, tcon,
                                                       cfile->fid.netfid,
                                                       (__u8)li->type, 0, num,
                                                       buf);
                                if (stored_rc)
                                        rc = stored_rc;
                                cur = buf;
                                num = 0;
                        } else
                                cur++;
                }

                if (num) {
                        stored_rc = cifs_lockv(xid, tcon, cfile->fid.netfid,
                                               (__u8)types[i], 0, num, buf);
                        if (stored_rc)
                                rc = stored_rc;
                }
        }

        kfree(buf);
        free_xid(xid);
        return rc;
}

static __u32
hash_lockowner(fl_owner_t owner)
{
        return cifs_lock_secret ^ hash32_ptr((const void *)owner);
}

struct lock_to_push {
        struct list_head llist;
        __u64 offset;
        __u64 length;
        __u32 pid;
        __u16 netfid;
        __u8 type;
};

static int
cifs_push_posix_locks(struct cifsFileInfo *cfile)
{
        struct inode *inode = d_inode(cfile->dentry);
        struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
        struct file_lock *flock;
        struct file_lock_context *flctx = inode->i_flctx;
        unsigned int count = 0, i;
        int rc = 0, xid, type;
        struct list_head locks_to_send, *el;
        struct lock_to_push *lck, *tmp;
        __u64 length;

        xid = get_xid();

        if (!flctx)
                goto out;

        spin_lock(&flctx->flc_lock);
        list_for_each(el, &flctx->flc_posix) {
                count++;
        }
        spin_unlock(&flctx->flc_lock);

        INIT_LIST_HEAD(&locks_to_send);

        /*
         * Allocating count locks is enough because no FL_POSIX locks can be
         * added to the list while we are holding cinode->lock_sem that
         * protects locking operations of this inode.
         */
        for (i = 0; i < count; i++) {
                lck = kmalloc(sizeof(struct lock_to_push), GFP_KERNEL);
                if (!lck) {
                        rc = -ENOMEM;
                        goto err_out;
                }
                list_add_tail(&lck->llist, &locks_to_send);
        }

        el = locks_to_send.next;
        spin_lock(&flctx->flc_lock);
        list_for_each_entry(flock, &flctx->flc_posix, fl_list) {
                if (el == &locks_to_send) {
                        /*
                         * The list ended. We don't have enough allocated
                         * structures - something is really wrong.
                         */
                        cifs_dbg(VFS, "Can't push all brlocks!\n");
                        break;
                }
                length = 1 + flock->fl_end - flock->fl_start;
                if (flock->fl_type == F_RDLCK || flock->fl_type == F_SHLCK)
                        type = CIFS_RDLCK;
                else
                        type = CIFS_WRLCK;
                lck = list_entry(el, struct lock_to_push, llist);
                lck->pid = hash_lockowner(flock->fl_owner);
                lck->netfid = cfile->fid.netfid;
                lck->length = length;
                lck->type = type;
                lck->offset = flock->fl_start;
        }
        spin_unlock(&flctx->flc_lock);

        list_for_each_entry_safe(lck, tmp, &locks_to_send, llist) {
                int stored_rc;

                stored_rc = CIFSSMBPosixLock(xid, tcon, lck->netfid, lck->pid,
                                             lck->offset, lck->length, NULL,
                                             lck->type, 0);
                if (stored_rc)
                        rc = stored_rc;
                list_del(&lck->llist);
                kfree(lck);
        }

out:
        free_xid(xid);
        return rc;
err_out:
        list_for_each_entry_safe(lck, tmp, &locks_to_send, llist) {
                list_del(&lck->llist);
                kfree(lck);
        }
        goto out;
}

static int
cifs_push_locks(struct cifsFileInfo *cfile)
{
        struct cifs_sb_info *cifs_sb = CIFS_SB(cfile->dentry->d_sb);
        struct cifsInodeInfo *cinode = CIFS_I(d_inode(cfile->dentry));
        struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
        int rc = 0;

        /* we are going to update can_cache_brlcks here - need a write access */
        cifs_down_write(&cinode->lock_sem);
        if (!cinode->can_cache_brlcks) {
                up_write(&cinode->lock_sem);
                return rc;
        }

        if (cap_unix(tcon->ses) &&
            (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
            ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
                rc = cifs_push_posix_locks(cfile);
        else
                rc = tcon->ses->server->ops->push_mand_locks(cfile);

        cinode->can_cache_brlcks = false;
        up_write(&cinode->lock_sem);
        return rc;
}

static void
cifs_read_flock(struct file_lock *flock, __u32 *type, int *lock, int *unlock,
                bool *wait_flag, struct TCP_Server_Info *server)
{
        if (flock->fl_flags & FL_POSIX)
                cifs_dbg(FYI, "Posix\n");
        if (flock->fl_flags & FL_FLOCK)
                cifs_dbg(FYI, "Flock\n");
        if (flock->fl_flags & FL_SLEEP) {
                cifs_dbg(FYI, "Blocking lock\n");
                *wait_flag = true;
        }
        if (flock->fl_flags & FL_ACCESS)
                cifs_dbg(FYI, "Process suspended by mandatory locking - not implemented yet\n");
        if (flock->fl_flags & FL_LEASE)
                cifs_dbg(FYI, "Lease on file - not implemented yet\n");
        if (flock->fl_flags &
            (~(FL_POSIX | FL_FLOCK | FL_SLEEP |
               FL_ACCESS | FL_LEASE | FL_CLOSE | FL_OFDLCK)))
                cifs_dbg(FYI, "Unknown lock flags 0x%x\n", flock->fl_flags);

        *type = server->vals->large_lock_type;
        if (flock->fl_type == F_WRLCK) {
                cifs_dbg(FYI, "F_WRLCK\n");
                *type |= server->vals->exclusive_lock_type;
                *lock = 1;
        } else if (flock->fl_type == F_UNLCK) {
                cifs_dbg(FYI, "F_UNLCK\n");
                *type |= server->vals->unlock_lock_type;
                *unlock = 1;
                /* Check if unlock includes more than one lock range */
        } else if (flock->fl_type == F_RDLCK) {
                cifs_dbg(FYI, "F_RDLCK\n");
                *type |= server->vals->shared_lock_type;
                *lock = 1;
        } else if (flock->fl_type == F_EXLCK) {
                cifs_dbg(FYI, "F_EXLCK\n");
                *type |= server->vals->exclusive_lock_type;
                *lock = 1;
        } else if (flock->fl_type == F_SHLCK) {
                cifs_dbg(FYI, "F_SHLCK\n");
                *type |= server->vals->shared_lock_type;
                *lock = 1;
        } else
                cifs_dbg(FYI, "Unknown type of lock\n");
}

static int
cifs_getlk(struct file *file, struct file_lock *flock, __u32 type,
           bool wait_flag, bool posix_lck, unsigned int xid)
{
        int rc = 0;
        __u64 length = 1 + flock->fl_end - flock->fl_start;
        struct cifsFileInfo *cfile = (struct cifsFileInfo *)file->private_data;
        struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
        struct TCP_Server_Info *server = tcon->ses->server;
        __u16 netfid = cfile->fid.netfid;

        if (posix_lck) {
                int posix_lock_type;

                rc = cifs_posix_lock_test(file, flock);
                if (!rc)
                        return rc;

                if (type & server->vals->shared_lock_type)
                        posix_lock_type = CIFS_RDLCK;
                else
                        posix_lock_type = CIFS_WRLCK;
                rc = CIFSSMBPosixLock(xid, tcon, netfid,
                                      hash_lockowner(flock->fl_owner),
                                      flock->fl_start, length, flock,
                                      posix_lock_type, wait_flag);
                return rc;
        }

        rc = cifs_lock_test(cfile, flock->fl_start, length, type, flock);
        if (!rc)
                return rc;

        /* BB we could chain these into one lock request BB */
        rc = server->ops->mand_lock(xid, cfile, flock->fl_start, length, type,
                                    1, 0, false);
        if (rc == 0) {
                rc = server->ops->mand_lock(xid, cfile, flock->fl_start, length,
                                            type, 0, 1, false);
                flock->fl_type = F_UNLCK;
                if (rc != 0)
                        cifs_dbg(VFS, "Error unlocking previously locked range %d during test of lock\n",
                                 rc);
                return 0;
        }

        if (type & server->vals->shared_lock_type) {
                flock->fl_type = F_WRLCK;
                return 0;
        }

        type &= ~server->vals->exclusive_lock_type;

        rc = server->ops->mand_lock(xid, cfile, flock->fl_start, length,
                                    type | server->vals->shared_lock_type,
                                    1, 0, false);
        if (rc == 0) {
                rc = server->ops->mand_lock(xid, cfile, flock->fl_start, length,
                        type | server->vals->shared_lock_type, 0, 1, false);
                flock->fl_type = F_RDLCK;
                if (rc != 0)
                        cifs_dbg(VFS, "Error unlocking previously locked range %d during test of lock\n",
                                 rc);
        } else
                flock->fl_type = F_WRLCK;

        return 0;
}

void
cifs_move_llist(struct list_head *source, struct list_head *dest)
{
        struct list_head *li, *tmp;
        list_for_each_safe(li, tmp, source)
                list_move(li, dest);
}

void
cifs_free_llist(struct list_head *llist)
{
        struct cifsLockInfo *li, *tmp;
        list_for_each_entry_safe(li, tmp, llist, llist) {
                cifs_del_lock_waiters(li);
                list_del(&li->llist);
                kfree(li);
        }
}

int
cifs_unlock_range(struct cifsFileInfo *cfile, struct file_lock *flock,
                  unsigned int xid)
{
        int rc = 0, stored_rc;
        static const int types[] = {
                LOCKING_ANDX_LARGE_FILES,
                LOCKING_ANDX_SHARED_LOCK | LOCKING_ANDX_LARGE_FILES
        };
        unsigned int i;
        unsigned int max_num, num, max_buf;
        LOCKING_ANDX_RANGE *buf, *cur;
        struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
        struct cifsInodeInfo *cinode = CIFS_I(d_inode(cfile->dentry));
        struct cifsLockInfo *li, *tmp;
        __u64 length = 1 + flock->fl_end - flock->fl_start;
        struct list_head tmp_llist;

        INIT_LIST_HEAD(&tmp_llist);

        /*
         * Accessing maxBuf is racy with cifs_reconnect - need to store value
         * and check it before using.
         */
        max_buf = tcon->ses->server->maxBuf;
        if (max_buf < (sizeof(struct smb_hdr) + sizeof(LOCKING_ANDX_RANGE)))
                return -EINVAL;

        BUILD_BUG_ON(sizeof(struct smb_hdr) + sizeof(LOCKING_ANDX_RANGE) >
                     PAGE_SIZE);
        max_buf = min_t(unsigned int, max_buf - sizeof(struct smb_hdr),
                        PAGE_SIZE);
        max_num = (max_buf - sizeof(struct smb_hdr)) /
                                                sizeof(LOCKING_ANDX_RANGE);
        buf = kcalloc(max_num, sizeof(LOCKING_ANDX_RANGE), GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        cifs_down_write(&cinode->lock_sem);
        for (i = 0; i < 2; i++) {
                cur = buf;
                num = 0;
                list_for_each_entry_safe(li, tmp, &cfile->llist->locks, llist) {
                        if (flock->fl_start > li->offset ||
                            (flock->fl_start + length) <
                            (li->offset + li->length))
                                continue;
                        if (current->tgid != li->pid)
                                continue;
                        if (types[i] != li->type)
                                continue;
                        if (cinode->can_cache_brlcks) {
                                /*
                                 * We can cache brlock requests - simply remove
                                 * a lock from the file's list.
                                 */
                                list_del(&li->llist);
                                cifs_del_lock_waiters(li);
                                kfree(li);
                                continue;
                        }
                        cur->Pid = cpu_to_le16(li->pid);
                        cur->LengthLow = cpu_to_le32((u32)li->length);
                        cur->LengthHigh = cpu_to_le32((u32)(li->length>>32));
                        cur->OffsetLow = cpu_to_le32((u32)li->offset);
                        cur->OffsetHigh = cpu_to_le32((u32)(li->offset>>32));
                        /*
                         * We need to save a lock here to let us add it again to
                         * the file's list if the unlock range request fails on
                         * the server.
                         */
                        list_move(&li->llist, &tmp_llist);
                        if (++num == max_num) {
                                stored_rc = cifs_lockv(xid, tcon,
                                                       cfile->fid.netfid,
                                                       li->type, num, 0, buf);
                                if (stored_rc) {
                                        /*
                                         * We failed on the unlock range
                                         * request - add all locks from the tmp
                                         * list to the head of the file's list.
                                         */
                                        cifs_move_llist(&tmp_llist,
                                                        &cfile->llist->locks);
                                        rc = stored_rc;
                                } else
                                        /*
                                         * The unlock range request succeed -
                                         * free the tmp list.
                                         */
                                        cifs_free_llist(&tmp_llist);
                                cur = buf;
                                num = 0;
                        } else
                                cur++;
                }
                if (num) {
                        stored_rc = cifs_lockv(xid, tcon, cfile->fid.netfid,
                                               types[i], num, 0, buf);
                        if (stored_rc) {
                                cifs_move_llist(&tmp_llist,
                                                &cfile->llist->locks);
                                rc = stored_rc;
                        } else
                                cifs_free_llist(&tmp_llist);
                }
        }

        up_write(&cinode->lock_sem);
        kfree(buf);
        return rc;
}

static int
cifs_setlk(struct file *file, struct file_lock *flock, __u32 type,
           bool wait_flag, bool posix_lck, int lock, int unlock,
           unsigned int xid)
{
        int rc = 0;
        __u64 length = 1 + flock->fl_end - flock->fl_start;
        struct cifsFileInfo *cfile = (struct cifsFileInfo *)file->private_data;
        struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
        struct TCP_Server_Info *server = tcon->ses->server;
        struct inode *inode = d_inode(cfile->dentry);

        if (posix_lck) {
                int posix_lock_type;

                rc = cifs_posix_lock_set(file, flock);
                if (rc <= FILE_LOCK_DEFERRED)
                        return rc;

                if (type & server->vals->shared_lock_type)
                        posix_lock_type = CIFS_RDLCK;
                else
                        posix_lock_type = CIFS_WRLCK;

                if (unlock == 1)
                        posix_lock_type = CIFS_UNLCK;

                rc = CIFSSMBPosixLock(xid, tcon, cfile->fid.netfid,
                                      hash_lockowner(flock->fl_owner),
                                      flock->fl_start, length,
                                      NULL, posix_lock_type, wait_flag);
                goto out;
        }

        if (lock) {
                struct cifsLockInfo *lock;

                lock = cifs_lock_init(flock->fl_start, length, type,
                                      flock->fl_flags);
                if (!lock)
                        return -ENOMEM;

                rc = cifs_lock_add_if(cfile, lock, wait_flag);
                if (rc < 0) {
                        kfree(lock);
                        return rc;
                }
                if (!rc)
                        goto out;

                /*
                 * Windows 7 server can delay breaking lease from read to None
                 * if we set a byte-range lock on a file - break it explicitly
                 * before sending the lock to the server to be sure the next
                 * read won't conflict with non-overlapted locks due to
                 * pagereading.
                 */
                if (!CIFS_CACHE_WRITE(CIFS_I(inode)) &&
                                        CIFS_CACHE_READ(CIFS_I(inode))) {
                        cifs_zap_mapping(inode);
                        cifs_dbg(FYI, "Set no oplock for inode=%p due to mand locks\n",
                                 inode);
                        CIFS_I(inode)->oplock = 0;
                }

                rc = server->ops->mand_lock(xid, cfile, flock->fl_start, length,
                                            type, 1, 0, wait_flag);
                if (rc) {
                        kfree(lock);
                        return rc;
                }

                cifs_lock_add(cfile, lock);
        } else if (unlock)
                rc = server->ops->mand_unlock_range(cfile, flock, xid);

out:
        if ((flock->fl_flags & FL_POSIX) || (flock->fl_flags & FL_FLOCK)) {
                /*
                 * If this is a request to remove all locks because we
                 * are closing the file, it doesn't matter if the
                 * unlocking failed as both cifs.ko and the SMB server
                 * remove the lock on file close
                 */
                if (rc) {
                        cifs_dbg(VFS, "%s failed rc=%d\n", __func__, rc);
                        if (!(flock->fl_flags & FL_CLOSE))
                                return rc;
                }
                rc = locks_lock_file_wait(file, flock);
        }
        return rc;
}

int cifs_flock(struct file *file, int cmd, struct file_lock *fl)
{
        int rc, xid;
        int lock = 0, unlock = 0;
        bool wait_flag = false;
        bool posix_lck = false;
        struct cifs_sb_info *cifs_sb;
        struct cifs_tcon *tcon;
        struct cifsFileInfo *cfile;
        __u32 type;

        rc = -EACCES;
        xid = get_xid();

        if (!(fl->fl_flags & FL_FLOCK))
                return -ENOLCK;

        cfile = (struct cifsFileInfo *)file->private_data;
        tcon = tlink_tcon(cfile->tlink);

        cifs_read_flock(fl, &type, &lock, &unlock, &wait_flag,
                        tcon->ses->server);
        cifs_sb = CIFS_FILE_SB(file);

        if (cap_unix(tcon->ses) &&
            (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
            ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
                posix_lck = true;

        if (!lock && !unlock) {
                /*
                 * if no lock or unlock then nothing to do since we do not
                 * know what it is
                 */
                free_xid(xid);
                return -EOPNOTSUPP;
        }

        rc = cifs_setlk(file, fl, type, wait_flag, posix_lck, lock, unlock,
                        xid);
        free_xid(xid);
        return rc;


}

int cifs_lock(struct file *file, int cmd, struct file_lock *flock)
{
        int rc, xid;
        int lock = 0, unlock = 0;
        bool wait_flag = false;
        bool posix_lck = false;
        struct cifs_sb_info *cifs_sb;
        struct cifs_tcon *tcon;
        struct cifsFileInfo *cfile;
        __u32 type;

        rc = -EACCES;
        xid = get_xid();

        cifs_dbg(FYI, "Lock parm: 0x%x flockflags: 0x%x flocktype: 0x%x start: %lld end: %lld\n",
                 cmd, flock->fl_flags, flock->fl_type,
                 flock->fl_start, flock->fl_end);

        cfile = (struct cifsFileInfo *)file->private_data;
        tcon = tlink_tcon(cfile->tlink);

        cifs_read_flock(flock, &type, &lock, &unlock, &wait_flag,
                        tcon->ses->server);
        cifs_sb = CIFS_FILE_SB(file);
        set_bit(CIFS_INO_CLOSE_ON_LOCK, &CIFS_I(d_inode(cfile->dentry))->flags);

        if (cap_unix(tcon->ses) &&
            (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
            ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
                posix_lck = true;
        /*
         * BB add code here to normalize offset and length to account for
         * negative length which we can not accept over the wire.
         */
        if (IS_GETLK(cmd)) {
                rc = cifs_getlk(file, flock, type, wait_flag, posix_lck, xid);
                free_xid(xid);
                return rc;
        }

        if (!lock && !unlock) {
                /*
                 * if no lock or unlock then nothing to do since we do not
                 * know what it is
                 */
                free_xid(xid);
                return -EOPNOTSUPP;
        }

        rc = cifs_setlk(file, flock, type, wait_flag, posix_lck, lock, unlock,
                        xid);
        free_xid(xid);
        return rc;
}

/*
 * update the file size (if needed) after a write. Should be called with
 * the inode->i_lock held
 */
void
cifs_update_eof(struct cifsInodeInfo *cifsi, loff_t offset,
                      unsigned int bytes_written)
{
        loff_t end_of_write = offset + bytes_written;

        if (end_of_write > cifsi->server_eof)
                cifsi->server_eof = end_of_write;
}

static ssize_t
cifs_write(struct cifsFileInfo *open_file, __u32 pid, const char *write_data,
           size_t write_size, loff_t *offset)
{
        int rc = 0;
        unsigned int bytes_written = 0;
        unsigned int total_written;
        struct cifs_tcon *tcon;
        struct TCP_Server_Info *server;
        unsigned int xid;
        struct dentry *dentry = open_file->dentry;
        struct cifsInodeInfo *cifsi = CIFS_I(d_inode(dentry));
        struct cifs_io_parms io_parms = {0};

        cifs_dbg(FYI, "write %zd bytes to offset %lld of %pd\n",
                 write_size, *offset, dentry);

        tcon = tlink_tcon(open_file->tlink);
        server = tcon->ses->server;

        if (!server->ops->sync_write)
                return -ENOSYS;

        xid = get_xid();

        for (total_written = 0; write_size > total_written;
             total_written += bytes_written) {
                rc = -EAGAIN;
                while (rc == -EAGAIN) {
                        struct kvec iov[2];
                        unsigned int len;

                        if (open_file->invalidHandle) {
                                /* we could deadlock if we called
                                   filemap_fdatawait from here so tell
                                   reopen_file not to flush data to
                                   server now */
                                rc = cifs_reopen_file(open_file, false);
                                if (rc != 0)
                                        break;
                        }

                        len = min(server->ops->wp_retry_size(d_inode(dentry)),
                                  (unsigned int)write_size - total_written);
                        /* iov[0] is reserved for smb header */
                        iov[1].iov_base = (char *)write_data + total_written;
                        iov[1].iov_len = len;
                        io_parms.pid = pid;
                        io_parms.tcon = tcon;
                        io_parms.offset = *offset;
                        io_parms.length = len;
                        rc = server->ops->sync_write(xid, &open_file->fid,
                                        &io_parms, &bytes_written, iov, 1);
                }
                if (rc || (bytes_written == 0)) {
                        if (total_written)
                                break;
                        else {
                                free_xid(xid);
                                return rc;
                        }
                } else {
                        spin_lock(&d_inode(dentry)->i_lock);
                        cifs_update_eof(cifsi, *offset, bytes_written);
                        spin_unlock(&d_inode(dentry)->i_lock);
                        *offset += bytes_written;
                }
        }

        cifs_stats_bytes_written(tcon, total_written);

        if (total_written > 0) {
                spin_lock(&d_inode(dentry)->i_lock);
                if (*offset > d_inode(dentry)->i_size) {
                        i_size_write(d_inode(dentry), *offset);
                        d_inode(dentry)->i_blocks = (512 - 1 + *offset) >> 9;
                }
                spin_unlock(&d_inode(dentry)->i_lock);
        }
        mark_inode_dirty_sync(d_inode(dentry));
        free_xid(xid);
        return total_written;
}

struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode,
                                        bool fsuid_only)
{
        struct cifsFileInfo *open_file = NULL;

        struct cifs_sb_info *cifs_sb = CIFS_SB(cifs_inode->vfs_inode.i_sb);

        /* only filter by fsuid on multiuser mounts */
        if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
                fsuid_only = false;

        spin_lock(&cifs_inode->open_file_lock);
        /* we could simply get the first_list_entry since write-only entries
           are always at the end of the list but since the first entry might
           have a close pending, we go through the whole list */
        list_for_each_entry(open_file, &cifs_inode->openFileList, flist) {
                if (fsuid_only && !uid_eq(open_file->uid, current_fsuid()))
                        continue;
                if (OPEN_FMODE(open_file->f_flags) & FMODE_READ) {
                        if ((!open_file->invalidHandle)) {
                                /* found a good file */
                                /* lock it so it will not be closed on us */
                                cifsFileInfo_get(open_file);
                                spin_unlock(&cifs_inode->open_file_lock);
                                return open_file;
                        } /* else might as well continue, and look for
                             another, or simply have the caller reopen it
                             again rather than trying to fix this handle */
                } else /* write only file */
                        break; /* write only files are last so must be done */
        }
        spin_unlock(&cifs_inode->open_file_lock);
        return NULL;
}

/* Return -EBADF if no handle is found and general rc otherwise */
int
cifs_get_writable_file(struct cifsInodeInfo *cifs_inode, int flags,
                       struct cifsFileInfo **ret_file)
{
        struct cifsFileInfo *open_file, *inv_file = NULL;
        struct cifs_sb_info *cifs_sb;
        bool any_available = false;
        int rc = -EBADF;
        unsigned int refind = 0;
        bool fsuid_only = flags & FIND_WR_FSUID_ONLY;
        bool with_delete = flags & FIND_WR_WITH_DELETE;
        *ret_file = NULL;

        /*
         * Having a null inode here (because mapping->host was set to zero by
         * the VFS or MM) should not happen but we had reports of on oops (due
         * to it being zero) during stress testcases so we need to check for it
         */

        if (cifs_inode == NULL) {
                cifs_dbg(VFS, "Null inode passed to cifs_writeable_file\n");
                dump_stack();
                return rc;
        }

        cifs_sb = CIFS_SB(cifs_inode->vfs_inode.i_sb);

        /* only filter by fsuid on multiuser mounts */
        if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
                fsuid_only = false;

        spin_lock(&cifs_inode->open_file_lock);
refind_writable:
        if (refind > MAX_REOPEN_ATT) {
                spin_unlock(&cifs_inode->open_file_lock);
                return rc;
        }
        list_for_each_entry(open_file, &cifs_inode->openFileList, flist) {
                if (!any_available && open_file->pid != current->tgid)
                        continue;
                if (fsuid_only && !uid_eq(open_file->uid, current_fsuid()))
                        continue;
                if (with_delete && !(open_file->fid.access & DELETE))
                        continue;
                if (OPEN_FMODE(open_file->f_flags) & FMODE_WRITE) {
                        if (!open_file->invalidHandle) {
                                /* found a good writable file */
                                cifsFileInfo_get(open_file);
                                spin_unlock(&cifs_inode->open_file_lock);
                                *ret_file = open_file;
                                return 0;
                        } else {
                                if (!inv_file)
                                        inv_file = open_file;
                        }
                }
        }
        /* couldn't find useable FH with same pid, try any available */
        if (!any_available) {
                any_available = true;
                goto refind_writable;
        }

        if (inv_file) {
                any_available = false;
                cifsFileInfo_get(inv_file);
        }

        spin_unlock(&cifs_inode->open_file_lock);

        if (inv_file) {
                rc = cifs_reopen_file(inv_file, false);
                if (!rc) {
                        *ret_file = inv_file;
                        return 0;
                }

                spin_lock(&cifs_inode->open_file_lock);
                list_move_tail(&inv_file->flist, &cifs_inode->openFileList);
                spin_unlock(&cifs_inode->open_file_lock);
                cifsFileInfo_put(inv_file);
                ++refind;
                inv_file = NULL;
                spin_lock(&cifs_inode->open_file_lock);
                goto refind_writable;
        }

        return rc;
}

struct cifsFileInfo *
find_writable_file(struct cifsInodeInfo *cifs_inode, int flags)
{
        struct cifsFileInfo *cfile;
        int rc;

        rc = cifs_get_writable_file(cifs_inode, flags, &cfile);
        if (rc)
                cifs_dbg(FYI, "Couldn't find writable handle rc=%d\n", rc);

        return cfile;
}

int
cifs_get_writable_path(struct cifs_tcon *tcon, const char *name,
                       int flags,
                       struct cifsFileInfo **ret_file)
{
        struct cifsFileInfo *cfile;
        void *page = alloc_dentry_path();

        *ret_file = NULL;

        spin_lock(&tcon->open_file_lock);
        list_for_each_entry(cfile, &tcon->openFileList, tlist) {
                struct cifsInodeInfo *cinode;
                const char *full_path = build_path_from_dentry(cfile->dentry, page);
                if (IS_ERR(full_path)) {
                        spin_unlock(&tcon->open_file_lock);
                        free_dentry_path(page);
                        return PTR_ERR(full_path);
                }
                if (strcmp(full_path, name))
                        continue;

                cinode = CIFS_I(d_inode(cfile->dentry));
                spin_unlock(&tcon->open_file_lock);
                free_dentry_path(page);
                return cifs_get_writable_file(cinode, flags, ret_file);
        }

        spin_unlock(&tcon->open_file_lock);
        free_dentry_path(page);
        return -ENOENT;
}

int
cifs_get_readable_path(struct cifs_tcon *tcon, const char *name,
                       struct cifsFileInfo **ret_file)
{
        struct cifsFileInfo *cfile;
        void *page = alloc_dentry_path();

        *ret_file = NULL;

        spin_lock(&tcon->open_file_lock);
        list_for_each_entry(cfile, &tcon->openFileList, tlist) {
                struct cifsInodeInfo *cinode;
                const char *full_path = build_path_from_dentry(cfile->dentry, page);
                if (IS_ERR(full_path)) {
                        spin_unlock(&tcon->open_file_lock);
                        free_dentry_path(page);
                        return PTR_ERR(full_path);
                }
                if (strcmp(full_path, name))
                        continue;

                cinode = CIFS_I(d_inode(cfile->dentry));
                spin_unlock(&tcon->open_file_lock);
                free_dentry_path(page);
                *ret_file = find_readable_file(cinode, 0);
                return *ret_file ? 0 : -ENOENT;
        }

        spin_unlock(&tcon->open_file_lock);
        free_dentry_path(page);
        return -ENOENT;
}

static int cifs_partialpagewrite(struct page *page, unsigned from, unsigned to)
{
        struct address_space *mapping = page->mapping;
        loff_t offset = (loff_t)page->index << PAGE_SHIFT;
        char *write_data;
        int rc = -EFAULT;
        int bytes_written = 0;
        struct inode *inode;
        struct cifsFileInfo *open_file;

        if (!mapping || !mapping->host)
                return -EFAULT;

        inode = page->mapping->host;

        offset += (loff_t)from;
        write_data = kmap(page);
        write_data += from;

        if ((to > PAGE_SIZE) || (from > to)) {
                kunmap(page);
                return -EIO;
        }

        /* racing with truncate? */
        if (offset > mapping->host->i_size) {
                kunmap(page);
                return 0; /* don't care */
        }

        /* check to make sure that we are not extending the file */
        if (mapping->host->i_size - offset < (loff_t)to)
                to = (unsigned)(mapping->host->i_size - offset);

        rc = cifs_get_writable_file(CIFS_I(mapping->host), FIND_WR_ANY,
                                    &open_file);
        if (!rc) {
                bytes_written = cifs_write(open_file, open_file->pid,
                                           write_data, to - from, &offset);
                cifsFileInfo_put(open_file);
                /* Does mm or vfs already set times? */
                inode->i_atime = inode->i_mtime = current_time(inode);
                if ((bytes_written > 0) && (offset))
                        rc = 0;
                else if (bytes_written < 0)
                        rc = bytes_written;
                else
                        rc = -EFAULT;
        } else {
                cifs_dbg(FYI, "No writable handle for write page rc=%d\n", rc);
                if (!is_retryable_error(rc))
                        rc = -EIO;
        }

        kunmap(page);
        return rc;
}

static struct cifs_writedata *
wdata_alloc_and_fillpages(pgoff_t tofind, struct address_space *mapping,
                          pgoff_t end, pgoff_t *index,
                          unsigned int *found_pages)
{
        struct cifs_writedata *wdata;

        wdata = cifs_writedata_alloc((unsigned int)tofind,
                                     cifs_writev_complete);
        if (!wdata)
                return NULL;

        *found_pages = find_get_pages_range_tag(mapping, index, end,
                                PAGECACHE_TAG_DIRTY, tofind, wdata->pages);
        return wdata;
}

static unsigned int
wdata_prepare_pages(struct cifs_writedata *wdata, unsigned int found_pages,
                    struct address_space *mapping,
                    struct writeback_control *wbc,
                    pgoff_t end, pgoff_t *index, pgoff_t *next, bool *done)
{
        unsigned int nr_pages = 0, i;
        struct page *page;

        for (i = 0; i < found_pages; i++) {
                page = wdata->pages[i];
                /*
                 * At this point we hold neither the i_pages lock nor the
                 * page lock: the page may be truncated or invalidated
                 * (changing page->mapping to NULL), or even swizzled
                 * back from swapper_space to tmpfs file mapping
                 */

                if (nr_pages == 0)
                        lock_page(page);
                else if (!trylock_page(page))
                        break;

                if (unlikely(page->mapping != mapping)) {
                        unlock_page(page);
                        break;
                }

                if (!wbc->range_cyclic && page->index > end) {
                        *done = true;
                        unlock_page(page);
                        break;
                }

                if (*next && (page->index != *next)) {
                        /* Not next consecutive page */
                        unlock_page(page);
                        break;
                }

                if (wbc->sync_mode != WB_SYNC_NONE)
                        wait_on_page_writeback(page);

                if (PageWriteback(page) ||
                                !clear_page_dirty_for_io(page)) {
                        unlock_page(page);
                        break;
                }

                /*
                 * This actually clears the dirty bit in the radix tree.
                 * See cifs_writepage() for more commentary.
                 */
                set_page_writeback(page);
                if (page_offset(page) >= i_size_read(mapping->host)) {
                        *done = true;
                        unlock_page(page);
                        end_page_writeback(page);
                        break;
                }

                wdata->pages[i] = page;
                *next = page->index + 1;
                ++nr_pages;
        }

        /* reset index to refind any pages skipped */
        if (nr_pages == 0)
                *index = wdata->pages[0]->index + 1;

        /* put any pages we aren't going to use */
        for (i = nr_pages; i < found_pages; i++) {
                put_page(wdata->pages[i]);
                wdata->pages[i] = NULL;
        }

        return nr_pages;
}

static int
wdata_send_pages(struct cifs_writedata *wdata, unsigned int nr_pages,
                 struct address_space *mapping, struct writeback_control *wbc)
{
        int rc;

        wdata->sync_mode = wbc->sync_mode;
        wdata->nr_pages = nr_pages;
        wdata->offset = page_offset(wdata->pages[0]);
        wdata->pagesz = PAGE_SIZE;
        wdata->tailsz = min(i_size_read(mapping->host) -
                        page_offset(wdata->pages[nr_pages - 1]),
                        (loff_t)PAGE_SIZE);
        wdata->bytes = ((nr_pages - 1) * PAGE_SIZE) + wdata->tailsz;
        wdata->pid = wdata->cfile->pid;

        rc = adjust_credits(wdata->server, &wdata->credits, wdata->bytes);
        if (rc)
                return rc;

        if (wdata->cfile->invalidHandle)
                rc = -EAGAIN;
        else
                rc = wdata->server->ops->async_writev(wdata,
                                                      cifs_writedata_release);

        return rc;
}

static int cifs_writepages(struct address_space *mapping,
                           struct writeback_control *wbc)
{
        struct inode *inode = mapping->host;
        struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
        struct TCP_Server_Info *server;
        bool done = false, scanned = false, range_whole = false;
        pgoff_t end, index;
        struct cifs_writedata *wdata;
        struct cifsFileInfo *cfile = NULL;
        int rc = 0;
        int saved_rc = 0;
        unsigned int xid;

        /*
         * If wsize is smaller than the page cache size, default to writing
         * one page at a time via cifs_writepage
         */
        if (cifs_sb->ctx->wsize < PAGE_SIZE)
                return generic_writepages(mapping, wbc);

        xid = get_xid();
        if (wbc->range_cyclic) {
                index = mapping->writeback_index; /* Start from prev offset */
                end = -1;
        } else {
                index = wbc->range_start >> PAGE_SHIFT;
                end = wbc->range_end >> PAGE_SHIFT;
                if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
                        range_whole = true;
                scanned = true;
        }
        server = cifs_pick_channel(cifs_sb_master_tcon(cifs_sb)->ses);

retry:
        while (!done && index <= end) {
                unsigned int i, nr_pages, found_pages, wsize;
                pgoff_t next = 0, tofind, saved_index = index;
                struct cifs_credits credits_on_stack;
                struct cifs_credits *credits = &credits_on_stack;
                int get_file_rc = 0;

                if (cfile)
                        cifsFileInfo_put(cfile);

                rc = cifs_get_writable_file(CIFS_I(inode), FIND_WR_ANY, &cfile);

                /* in case of an error store it to return later */
                if (rc)
                        get_file_rc = rc;

                rc = server->ops->wait_mtu_credits(server, cifs_sb->ctx->wsize,
                                                   &wsize, credits);
                if (rc != 0) {
                        done = true;
                        break;
                }

                tofind = min((wsize / PAGE_SIZE) - 1, end - index) + 1;

                wdata = wdata_alloc_and_fillpages(tofind, mapping, end, &index,
                                                  &found_pages);
                if (!wdata) {
                        rc = -ENOMEM;
                        done = true;
                        add_credits_and_wake_if(server, credits, 0);
                        break;
                }

                if (found_pages == 0) {
                        kref_put(&wdata->refcount, cifs_writedata_release);
                        add_credits_and_wake_if(server, credits, 0);
                        break;
                }

                nr_pages = wdata_prepare_pages(wdata, found_pages, mapping, wbc,
                                               end, &index, &next, &done);

                /* nothing to write? */
                if (nr_pages == 0) {
                        kref_put(&wdata->refcount, cifs_writedata_release);
                        add_credits_and_wake_if(server, credits, 0);
                        continue;
                }

                wdata->credits = credits_on_stack;
                wdata->cfile = cfile;
                wdata->server = server;
                cfile = NULL;

                if (!wdata->cfile) {
                        cifs_dbg(VFS, "No writable handle in writepages rc=%d\n",
                                 get_file_rc);
                        if (is_retryable_error(get_file_rc))
                                rc = get_file_rc;
                        else
                                rc = -EBADF;
                } else
                        rc = wdata_send_pages(wdata, nr_pages, mapping, wbc);

                for (i = 0; i < nr_pages; ++i)
                        unlock_page(wdata->pages[i]);

                /* send failure -- clean up the mess */
                if (rc != 0) {
                        add_credits_and_wake_if(server, &wdata->credits, 0);
                        for (i = 0; i < nr_pages; ++i) {
                                if (is_retryable_error(rc))
                                        redirty_page_for_writepage(wbc,
                                                           wdata->pages[i]);
                                else
                                        SetPageError(wdata->pages[i]);
                                end_page_writeback(wdata->pages[i]);
                                put_page(wdata->pages[i]);
                        }
                        if (!is_retryable_error(rc))
                                mapping_set_error(mapping, rc);
                }
                kref_put(&wdata->refcount, cifs_writedata_release);

                if (wbc->sync_mode == WB_SYNC_ALL && rc == -EAGAIN) {
                        index = saved_index;
                        continue;
                }

                /* Return immediately if we received a signal during writing */
                if (is_interrupt_error(rc)) {
                        done = true;
                        break;
                }

                if (rc != 0 && saved_rc == 0)
                        saved_rc = rc;

                wbc->nr_to_write -= nr_pages;
                if (wbc->nr_to_write <= 0)
                        done = true;

                index = next;
        }

        if (!scanned && !done) {
                /*
                 * We hit the last page and there is more work to be done: wrap
                 * back to the start of the file
                 */
                scanned = true;
                index = 0;
                goto retry;
        }

        if (saved_rc != 0)
                rc = saved_rc;

        if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
                mapping->writeback_index = index;

        if (cfile)
                cifsFileInfo_put(cfile);
        free_xid(xid);
        /* Indication to update ctime and mtime as close is deferred */
        set_bit(CIFS_INO_MODIFIED_ATTR, &CIFS_I(inode)->flags);
        return rc;
}

static int
cifs_writepage_locked(struct page *page, struct writeback_control *wbc)
{
        int rc;
        unsigned int xid;

        xid = get_xid();
/* BB add check for wbc flags */
        get_page(page);
        if (!PageUptodate(page))
                cifs_dbg(FYI, "ppw - page not up to date\n");

        /*
         * Set the "writeback" flag, and clear "dirty" in the radix tree.
         *
         * A writepage() implementation always needs to do either this,
         * or re-dirty the page with "redirty_page_for_writepage()" in
         * the case of a failure.
         *
         * Just unlocking the page will cause the radix tree tag-bits
         * to fail to update with the state of the page correctly.
         */
        set_page_writeback(page);
retry_write:
        rc = cifs_partialpagewrite(page, 0, PAGE_SIZE);
        if (is_retryable_error(rc)) {
                if (wbc->sync_mode == WB_SYNC_ALL && rc == -EAGAIN)
                        goto retry_write;
                redirty_page_for_writepage(wbc, page);
        } else if (rc != 0) {
                SetPageError(page);
                mapping_set_error(page->mapping, rc);
        } else {
                SetPageUptodate(page);
        }
        end_page_writeback(page);
        put_page(page);
        free_xid(xid);
        return rc;
}

static int cifs_writepage(struct page *page, struct writeback_control *wbc)
{
        int rc = cifs_writepage_locked(page, wbc);
        unlock_page(page);
        return rc;
}

static int cifs_write_end(struct file *file, struct address_space *mapping,
                        loff_t pos, unsigned len, unsigned copied,
                        struct page *page, void *fsdata)
{
        int rc;
        struct inode *inode = mapping->host;
        struct cifsFileInfo *cfile = file->private_data;
        struct cifs_sb_info *cifs_sb = CIFS_SB(cfile->dentry->d_sb);
        __u32 pid;

        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
                pid = cfile->pid;
        else
                pid = current->tgid;

        cifs_dbg(FYI, "write_end for page %p from pos %lld with %d bytes\n",
                 page, pos, copied);

        if (PageChecked(page)) {
                if (copied == len)
                        SetPageUptodate(page);
                ClearPageChecked(page);
        } else if (!PageUptodate(page) && copied == PAGE_SIZE)
                SetPageUptodate(page);

        if (!PageUptodate(page)) {
                char *page_data;
                unsigned offset = pos & (PAGE_SIZE - 1);
                unsigned int xid;

                xid = get_xid();
                /* this is probably better than directly calling
                   partialpage_write since in this function the file handle is
                   known which we might as well leverage */
                /* BB check if anything else missing out of ppw
                   such as updating last write time */
                page_data = kmap(page);
                rc = cifs_write(cfile, pid, page_data + offset, copied, &pos);
                /* if (rc < 0) should we set writebehind rc? */
                kunmap(page);

                free_xid(xid);
        } else {
                rc = copied;
                pos += copied;
                set_page_dirty(page);
        }

        if (rc > 0) {
                spin_lock(&inode->i_lock);
                if (pos > inode->i_size) {
                        i_size_write(inode, pos);
                        inode->i_blocks = (512 - 1 + pos) >> 9;
                }
                spin_unlock(&inode->i_lock);
        }

        unlock_page(page);
        put_page(page);
        /* Indication to update ctime and mtime as close is deferred */
        set_bit(CIFS_INO_MODIFIED_ATTR, &CIFS_I(inode)->flags);

        return rc;
}

int cifs_strict_fsync(struct file *file, loff_t start, loff_t end,
                      int datasync)
{
        unsigned int xid;
        int rc = 0;
        struct cifs_tcon *tcon;
        struct TCP_Server_Info *server;
        struct cifsFileInfo *smbfile = file->private_data;
        struct inode *inode = file_inode(file);
        struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);

        rc = file_write_and_wait_range(file, start, end);
        if (rc) {
                trace_cifs_fsync_err(inode->i_ino, rc);
                return rc;
        }

        xid = get_xid();

        cifs_dbg(FYI, "Sync file - name: %pD datasync: 0x%x\n",
                 file, datasync);

        if (!CIFS_CACHE_READ(CIFS_I(inode))) {
                rc = cifs_zap_mapping(inode);
                if (rc) {
                        cifs_dbg(FYI, "rc: %d during invalidate phase\n", rc);
                        rc = 0; /* don't care about it in fsync */
                }
        }

        tcon = tlink_tcon(smbfile->tlink);
        if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOSSYNC)) {
                server = tcon->ses->server;
                if (server->ops->flush)
                        rc = server->ops->flush(xid, tcon, &smbfile->fid);
                else
                        rc = -ENOSYS;
        }

        free_xid(xid);
        return rc;
}

int cifs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
        unsigned int xid;
        int rc = 0;
        struct cifs_tcon *tcon;
        struct TCP_Server_Info *server;
        struct cifsFileInfo *smbfile = file->private_data;
        struct cifs_sb_info *cifs_sb = CIFS_FILE_SB(file);

        rc = file_write_and_wait_range(file, start, end);
        if (rc) {
                trace_cifs_fsync_err(file_inode(file)->i_ino, rc);
                return rc;
        }

        xid = get_xid();

        cifs_dbg(FYI, "Sync file - name: %pD datasync: 0x%x\n",
                 file, datasync);

        tcon = tlink_tcon(smbfile->tlink);
        if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOSSYNC)) {
                server = tcon->ses->server;
                if (server->ops->flush)
                        rc = server->ops->flush(xid, tcon, &smbfile->fid);
                else
                        rc = -ENOSYS;
        }

        free_xid(xid);
        return rc;
}

/*
 * As file closes, flush all cached write data for this inode checking
 * for write behind errors.
 */
int cifs_flush(struct file *file, fl_owner_t id)
{
        struct inode *inode = file_inode(file);
        int rc = 0;

        if (file->f_mode & FMODE_WRITE)
                rc = filemap_write_and_wait(inode->i_mapping);

        cifs_dbg(FYI, "Flush inode %p file %p rc %d\n", inode, file, rc);
        if (rc)
                trace_cifs_flush_err(inode->i_ino, rc);
        return rc;
}

static int
cifs_write_allocate_pages(struct page **pages, unsigned long num_pages)
{
        int rc = 0;
        unsigned long i;

        for (i = 0; i < num_pages; i++) {
                pages[i] = alloc_page(GFP_KERNEL|__GFP_HIGHMEM);
                if (!pages[i]) {
                        /*
                         * save number of pages we have already allocated and
                         * return with ENOMEM error
                         */
                        num_pages = i;
                        rc = -ENOMEM;
                        break;
                }
        }

        if (rc) {
                for (i = 0; i < num_pages; i++)
                        put_page(pages[i]);
        }
        return rc;
}

static inline
size_t get_numpages(const size_t wsize, const size_t len, size_t *cur_len)
{
        size_t num_pages;
        size_t clen;

        clen = min_t(const size_t, len, wsize);
        num_pages = DIV_ROUND_UP(clen, PAGE_SIZE);

        if (cur_len)
                *cur_len = clen;

        return num_pages;
}

static void
cifs_uncached_writedata_release(struct kref *refcount)
{
        int i;
        struct cifs_writedata *wdata = container_of(refcount,
                                        struct cifs_writedata, refcount);

        kref_put(&wdata->ctx->refcount, cifs_aio_ctx_release);
        for (i = 0; i < wdata->nr_pages; i++)
                put_page(wdata->pages[i]);
        cifs_writedata_release(refcount);
}

static void collect_uncached_write_data(struct cifs_aio_ctx *ctx);

static void
cifs_uncached_writev_complete(struct work_struct *work)
{
        struct cifs_writedata *wdata = container_of(work,
                                        struct cifs_writedata, work);
        struct inode *inode = d_inode(wdata->cfile->dentry);
        struct cifsInodeInfo *cifsi = CIFS_I(inode);

        spin_lock(&inode->i_lock);
        cifs_update_eof(cifsi, wdata->offset, wdata->bytes);
        if (cifsi->server_eof > inode->i_size)
                i_size_write(inode, cifsi->server_eof);
        spin_unlock(&inode->i_lock);

        complete(&wdata->done);
        collect_uncached_write_data(wdata->ctx);
        /* the below call can possibly free the last ref to aio ctx */
        kref_put(&wdata->refcount, cifs_uncached_writedata_release);
}

static int
wdata_fill_from_iovec(struct cifs_writedata *wdata, struct iov_iter *from,
                      size_t *len, unsigned long *num_pages)
{
        size_t save_len, copied, bytes, cur_len = *len;
        unsigned long i, nr_pages = *num_pages;

        save_len = cur_len;
        for (i = 0; i < nr_pages; i++) {
                bytes = min_t(const size_t, cur_len, PAGE_SIZE);
                copied = copy_page_from_iter(wdata->pages[i], 0, bytes, from);
                cur_len -= copied;
                /*
                 * If we didn't copy as much as we expected, then that
                 * may mean we trod into an unmapped area. Stop copying
                 * at that point. On the next pass through the big
                 * loop, we'll likely end up getting a zero-length
                 * write and bailing out of it.
                 */
                if (copied < bytes)
                        break;
        }
        cur_len = save_len - cur_len;
        *len = cur_len;

        /*
         * If we have no data to send, then that probably means that
         * the copy above failed altogether. That's most likely because
         * the address in the iovec was bogus. Return -EFAULT and let
         * the caller free anything we allocated and bail out.
         */
        if (!cur_len)
                return -EFAULT;

        /*
         * i + 1 now represents the number of pages we actually used in
         * the copy phase above.
         */
        *num_pages = i + 1;
        return 0;
}

static int
cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list,
        struct cifs_aio_ctx *ctx)
{
        unsigned int wsize;
        struct cifs_credits credits;
        int rc;
        struct TCP_Server_Info *server = wdata->server;

        do {
                if (wdata->cfile->invalidHandle) {
                        rc = cifs_reopen_file(wdata->cfile, false);
                        if (rc == -EAGAIN)
                                continue;
                        else if (rc)
                                break;
                }


                /*
                 * Wait for credits to resend this wdata.
                 * Note: we are attempting to resend the whole wdata not in
                 * segments
                 */
                do {
                        rc = server->ops->wait_mtu_credits(server, wdata->bytes,
                                                &wsize, &credits);
                        if (rc)
                                goto fail;

                        if (wsize < wdata->bytes) {
                                add_credits_and_wake_if(server, &credits, 0);
                                msleep(1000);
                        }
                } while (wsize < wdata->bytes);
                wdata->credits = credits;

                rc = adjust_credits(server, &wdata->credits, wdata->bytes);

                if (!rc) {
                        if (wdata->cfile->invalidHandle)
                                rc = -EAGAIN;
                        else {
#ifdef CONFIG_CIFS_SMB_DIRECT
                                if (wdata->mr) {
                                        wdata->mr->need_invalidate = true;
                                        smbd_deregister_mr(wdata->mr);
                                        wdata->mr = NULL;
                                }
#endif
                                rc = server->ops->async_writev(wdata,
                                        cifs_uncached_writedata_release);
                        }
                }

                /* If the write was successfully sent, we are done */
                if (!rc) {
                        list_add_tail(&wdata->list, wdata_list);
                        return 0;
                }

                /* Roll back credits and retry if needed */
                add_credits_and_wake_if(server, &wdata->credits, 0);
        } while (rc == -EAGAIN);

fail:
        kref_put(&wdata->refcount, cifs_uncached_writedata_release);
        return rc;
}

static int
cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
                     struct cifsFileInfo *open_file,
                     struct cifs_sb_info *cifs_sb, struct list_head *wdata_list,
                     struct cifs_aio_ctx *ctx)
{
        int rc = 0;
        size_t cur_len;
        unsigned long nr_pages, num_pages, i;
        struct cifs_writedata *wdata;
        struct iov_iter saved_from = *from;
        loff_t saved_offset = offset;
        pid_t pid;
        struct TCP_Server_Info *server;
        struct page **pagevec;
        size_t start;
        unsigned int xid;

        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
                pid = open_file->pid;
        else
                pid = current->tgid;

        server = cifs_pick_channel(tlink_tcon(open_file->tlink)->ses);
        xid = get_xid();

        do {
                unsigned int wsize;
                struct cifs_credits credits_on_stack;
                struct cifs_credits *credits = &credits_on_stack;

                if (open_file->invalidHandle) {
                        rc = cifs_reopen_file(open_file, false);
                        if (rc == -EAGAIN)
                                continue;
                        else if (rc)
                                break;
                }

                rc = server->ops->wait_mtu_credits(server, cifs_sb->ctx->wsize,
                                                   &wsize, credits);
                if (rc)
                        break;

                cur_len = min_t(const size_t, len, wsize);

                if (ctx->direct_io) {
                        ssize_t result;

                        result = iov_iter_get_pages_alloc(
                                from, &pagevec, cur_len, &start);
                        if (result < 0) {
                                cifs_dbg(VFS,
                                         "direct_writev couldn't get user pages (rc=%zd) iter type %d iov_offset %zd count %zd\n",
                                         result, iov_iter_type(from),
                                         from->iov_offset, from->count);
                                dump_stack();