/*
 *  linux/fs/9p/vfs_file.c
 *
 * This file contians vfs file ops for 9P2000.
 *
 *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
 *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to:
 *  Free Software Foundation
 *  51 Franklin Street, Fifth Floor
 *  Boston, MA  02111-1301  USA
 *
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/file.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/inet.h>
#include <linux/list.h>
#include <linux/pagemap.h>
#include <linux/utsname.h>
#include <asm/uaccess.h>
#include <linux/idr.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>

#include "v9fs.h"
#include "v9fs_vfs.h"
#include "fid.h"
#include "cache.h"

static const struct vm_operations_struct v9fs_file_vm_ops;

/**
 * v9fs_file_open - open a file (or directory)
 * @inode: inode to be opened
 * @file: file being opened
 *
 */

int v9fs_file_open(struct inode *inode, struct file *file)
{
        int err;
        struct v9fs_inode *v9inode;
        struct v9fs_session_info *v9ses;
        struct p9_fid *fid;
        int omode;

        P9_DPRINTK(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, file);
        v9inode = V9FS_I(inode);
        v9ses = v9fs_inode2v9ses(inode);
        if (v9fs_proto_dotl(v9ses))
                omode = file->f_flags;
        else
                omode = v9fs_uflags2omode(file->f_flags,
                                        v9fs_proto_dotu(v9ses));
        fid = file->private_data;
        if (!fid) {
                fid = v9fs_fid_clone(file->f_path.dentry);
                if (IS_ERR(fid))
                        return PTR_ERR(fid);

                err = p9_client_open(fid, omode);
                if (err < 0) {
                        p9_client_clunk(fid);
                        return err;
                }
                if (file->f_flags & O_TRUNC) {
                        i_size_write(inode, 0);
                        inode->i_blocks = 0;
                }
                if ((file->f_flags & O_APPEND) &&
                        (!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)))
                        generic_file_llseek(file, 0, SEEK_END);
        }

        file->private_data = fid;
        mutex_lock(&v9inode->v_mutex);
        if (v9ses->cache && !v9inode->writeback_fid &&
            ((file->f_flags & O_ACCMODE) != O_RDONLY)) {
                /*
                 * clone a fid and add it to writeback_fid
                 * we do it during open time instead of
                 * page dirty time via write_begin/page_mkwrite
                 * because we want write after unlink usecase
                 * to work.
                 */
                fid = v9fs_writeback_fid(file->f_path.dentry);
                if (IS_ERR(fid)) {
                        err = PTR_ERR(fid);
                        mutex_unlock(&v9inode->v_mutex);
                        goto out_error;
                }
                v9inode->writeback_fid = (void *) fid;
        }
        mutex_unlock(&v9inode->v_mutex);
#ifdef CONFIG_9P_FSCACHE
        if (v9ses->cache)
                v9fs_cache_inode_set_cookie(inode, file);
#endif
        return 0;
out_error:
        p9_client_clunk(file->private_data);
        file->private_data = NULL;
        return err;
}

/**
 * v9fs_file_lock - lock a file (or directory)
 * @filp: file to be locked
 * @cmd: lock command
 * @fl: file lock structure
 *
 * Bugs: this looks like a local only lock, we should extend into 9P
 *       by using open exclusive
 */

static int v9fs_file_lock(struct file *filp, int cmd, struct file_lock *fl)
{
        int res = 0;
        struct inode *inode = filp->f_path.dentry->d_inode;

        P9_DPRINTK(P9_DEBUG_VFS, "filp: %p lock: %p\n", filp, fl);

        /* No mandatory locks */
        if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
                return -ENOLCK;

        if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
                filemap_write_and_wait(inode->i_mapping);
                invalidate_mapping_pages(&inode->i_data, 0, -1);
        }

        return res;
}

static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl)
{
        struct p9_flock flock;
        struct p9_fid *fid;
        uint8_t status;
        int res = 0;
        unsigned char fl_type;

        fid = filp->private_data;
        BUG_ON(fid == NULL);

        if ((fl->fl_flags & FL_POSIX) != FL_POSIX)
                BUG();

        res = posix_lock_file_wait(filp, fl);
        if (res < 0)
                goto out;

        /* convert posix lock to p9 tlock args */
        memset(&flock, 0, sizeof(flock));
        flock.type = fl->fl_type;
        flock.start = fl->fl_start;
        if (fl->fl_end == OFFSET_MAX)
                flock.length = 0;
        else
                flock.length = fl->fl_end - fl->fl_start + 1;
        flock.proc_id = fl->fl_pid;
        flock.client_id = utsname()->nodename;
        if (IS_SETLKW(cmd))
                flock.flags = P9_LOCK_FLAGS_BLOCK;

        /*
         * if its a blocked request and we get P9_LOCK_BLOCKED as the status
         * for lock request, keep on trying
         */
        for (;;) {
                res = p9_client_lock_dotl(fid, &flock, &status);
                if (res < 0)
                        break;

                if (status != P9_LOCK_BLOCKED)
                        break;
                if (status == P9_LOCK_BLOCKED && !IS_SETLKW(cmd))
                        break;
                schedule_timeout_interruptible(P9_LOCK_TIMEOUT);
        }

        /* map 9p status to VFS status */
        switch (status) {
        case P9_LOCK_SUCCESS:
                res = 0;
                break;
        case P9_LOCK_BLOCKED:
                res = -EAGAIN;
                break;
        case P9_LOCK_ERROR:
        case P9_LOCK_GRACE:
                res = -ENOLCK;
                break;
        default:
                BUG();
        }

        /*
         * incase server returned error for lock request, revert
         * it locally
         */
        if (res < 0 && fl->fl_type != F_UNLCK) {
                fl_type = fl->fl_type;
                fl->fl_type = F_UNLCK;
                res = posix_lock_file_wait(filp, fl);
                fl->fl_type = fl_type;
        }
out:
        return res;
}

static int v9fs_file_getlock(struct file *filp, struct file_lock *fl)
{
        struct p9_getlock glock;
        struct p9_fid *fid;
        int res = 0;

        fid = filp->private_data;
        BUG_ON(fid == NULL);

        posix_test_lock(filp, fl);
        /*
         * if we have a conflicting lock locally, no need to validate
         * with server
         */
        if (fl->fl_type != F_UNLCK)
                return res;

        /* convert posix lock to p9 tgetlock args */
        memset(&glock, 0, sizeof(glock));
        glock.type = fl->fl_type;
        glock.start = fl->fl_start;
        if (fl->fl_end == OFFSET_MAX)
                glock.length = 0;
        else
                glock.length = fl->fl_end - fl->fl_start + 1;
        glock.proc_id = fl->fl_pid;
        glock.client_id = utsname()->nodename;

        res = p9_client_getlock_dotl(fid, &glock);
        if (res < 0)
                return res;
        if (glock.type != F_UNLCK) {
                fl->fl_type = glock.type;
                fl->fl_start = glock.start;
                if (glock.length == 0)
                        fl->fl_end = OFFSET_MAX;
                else
                        fl->fl_end = glock.start + glock.length - 1;
                fl->fl_pid = glock.proc_id;
        } else
                fl->fl_type = F_UNLCK;

        return res;
}

/**
 * v9fs_file_lock_dotl - lock a file (or directory)
 * @filp: file to be locked
 * @cmd: lock command
 * @fl: file lock structure
 *
 */

static int v9fs_file_lock_dotl(struct file *filp, int cmd, struct file_lock *fl)
{
        struct inode *inode = filp->f_path.dentry->d_inode;
        int ret = -ENOLCK;

        P9_DPRINTK(P9_DEBUG_VFS, "filp: %p cmd:%d lock: %p name: %s\n", filp,
                                cmd, fl, filp->f_path.dentry->d_name.name);

        /* No mandatory locks */
        if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
                goto out_err;

        if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
                filemap_write_and_wait(inode->i_mapping);
                invalidate_mapping_pages(&inode->i_data, 0, -1);
        }

        if (IS_SETLK(cmd) || IS_SETLKW(cmd))
                ret = v9fs_file_do_lock(filp, cmd, fl);
        else if (IS_GETLK(cmd))
                ret = v9fs_file_getlock(filp, fl);
        else
                ret = -EINVAL;
out_err:
        return ret;
}

/**
 * v9fs_file_flock_dotl - lock a file
 * @filp: file to be locked
 * @cmd: lock command
 * @fl: file lock structure
 *
 */

static int v9fs_file_flock_dotl(struct file *filp, int cmd,
        struct file_lock *fl)
{
        struct inode *inode = filp->f_path.dentry->d_inode;
        int ret = -ENOLCK;

        P9_DPRINTK(P9_DEBUG_VFS, "filp: %p cmd:%d lock: %p name: %s\n", filp,
                                cmd, fl, filp->f_path.dentry->d_name.name);

        /* No mandatory locks */
        if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
                goto out_err;

        if (!(fl->fl_flags & FL_FLOCK))
                goto out_err;

        if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
                filemap_write_and_wait(inode->i_mapping);
                invalidate_mapping_pages(&inode->i_data, 0, -1);
        }
        /* Convert flock to posix lock */
        fl->fl_owner = (fl_owner_t)filp;
        fl->fl_start = 0;
        fl->fl_end = OFFSET_MAX;
        fl->fl_flags |= FL_POSIX;
        fl->fl_flags ^= FL_FLOCK;

        if (IS_SETLK(cmd) | IS_SETLKW(cmd))
                ret = v9fs_file_do_lock(filp, cmd, fl);
        else
                ret = -EINVAL;
out_err:
        return ret;
}

/**
 * v9fs_fid_readn - read from a fid
 * @fid: fid to read
 * @data: data buffer to read data into
 * @udata: user data buffer to read data into
 * @count: size of buffer
 * @offset: offset at which to read data
 *
 */
ssize_t
v9fs_fid_readn(struct p9_fid *fid, char *data, char __user *udata, u32 count,
               u64 offset)
{
        int n, total, size;

        P9_DPRINTK(P9_DEBUG_VFS, "fid %d offset %llu count %d\n", fid->fid,
                   (long long unsigned) offset, count);
        n = 0;
        total = 0;
        size = fid->iounit ? fid->iounit : fid->clnt->msize - P9_IOHDRSZ;
        do {
                n = p9_client_read(fid, data, udata, offset, count);
                if (n <= 0)
                        break;

                if (data)
                        data += n;
                if (udata)
                        udata += n;

                offset += n;
                count -= n;
                total += n;
        } while (count > 0 && n == size);

        if (n < 0)
                total = n;

        return total;
}

/**
 * v9fs_file_readn - read from a file
 * @filp: file pointer to read
 * @data: data buffer to read data into
 * @udata: user data buffer to read data into
 * @count: size of buffer
 * @offset: offset at which to read data
 *
 */
ssize_t
v9fs_file_readn(struct file *filp, char *data, char __user *udata, u32 count,
               u64 offset)
{
        return v9fs_fid_readn(filp->private_data, data, udata, count, offset);
}

/**
 * v9fs_file_read - read from a file
 * @filp: file pointer to read
 * @udata: user data buffer to read data into
 * @count: size of buffer
 * @offset: offset at which to read data
 *
 */

static ssize_t
v9fs_file_read(struct file *filp, char __user *udata, size_t count,
               loff_t * offset)
{
        int ret;
        struct p9_fid *fid;
        size_t size;

        P9_DPRINTK(P9_DEBUG_VFS, "count %zu offset %lld\n", count, *offset);
        fid = filp->private_data;

        size = fid->iounit ? fid->iounit : fid->clnt->msize - P9_IOHDRSZ;
        if (count > size)
                ret = v9fs_file_readn(filp, NULL, udata, count, *offset);
        else
                ret = p9_client_read(fid, NULL, udata, *offset, count);

        if (ret > 0)
                *offset += ret;

        return ret;
}

ssize_t
v9fs_file_write_internal(struct inode *inode, struct p9_fid *fid,
                         const char __user *data, size_t count,
                         loff_t *offset, int invalidate)
{
        int n;
        loff_t i_size;
        size_t total = 0;
        struct p9_client *clnt;
        loff_t origin = *offset;
        unsigned long pg_start, pg_end;

        P9_DPRINTK(P9_DEBUG_VFS, "data %p count %d offset %x\n", data,
                (int)count, (int)*offset);

        clnt = fid->clnt;
        do {
                n = p9_client_write(fid, NULL, data+total, origin+total, count);
                if (n <= 0)
                        break;
                count -= n;
                total += n;
        } while (count > 0);

        if (invalidate && (total > 0)) {
                pg_start = origin >> PAGE_CACHE_SHIFT;
                pg_end = (origin + total - 1) >> PAGE_CACHE_SHIFT;
                if (inode->i_mapping && inode->i_mapping->nrpages)
                        invalidate_inode_pages2_range(inode->i_mapping,
                                                      pg_start, pg_end);
                *offset += total;
                i_size = i_size_read(inode);
                if (*offset > i_size) {
                        inode_add_bytes(inode, *offset - i_size);
                        i_size_write(inode, *offset);
                }
        }
        if (n < 0)
                return n;

        return total;
}

/**
 * v9fs_file_write - write to a file
 * @filp: file pointer to write
 * @data: data buffer to write data from
 * @count: size of buffer
 * @offset: offset at which to write data
 *
 */
static ssize_t
v9fs_file_write(struct file *filp, const char __user * data,
                size_t count, loff_t *offset)
{
        ssize_t retval = 0;
        loff_t origin = *offset;


        retval = generic_write_checks(filp, &origin, &count, 0);
        if (retval)
                goto out;

        retval = -EINVAL;
        if ((ssize_t) count < 0)
                goto out;
        retval = 0;
        if (!count)
                goto out;

        retval = v9fs_file_write_internal(filp->f_path.dentry->d_inode,
                                        filp->private_data,
                                        data, count, &origin, 1);
        /* update offset on successful write */
        if (retval > 0)
                *offset = origin;
out:
        return retval;
}


static int v9fs_file_fsync(struct file *filp, int datasync)
{
        struct p9_fid *fid;
        struct p9_wstat wstat;
        int retval;

        P9_DPRINTK(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);

        fid = filp->private_data;
        v9fs_blank_wstat(&wstat);

        retval = p9_client_wstat(fid, &wstat);
        return retval;
}

int v9fs_file_fsync_dotl(struct file *filp, int datasync)
{
        struct p9_fid *fid;
        int retval;

        P9_DPRINTK(P9_DEBUG_VFS, "v9fs_file_fsync_dotl: filp %p datasync %x\n",
                        filp, datasync);

        fid = filp->private_data;

        retval = p9_client_fsync(fid, datasync);
        return retval;
}

static int
v9fs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
        int retval;

        retval = generic_file_mmap(file, vma);
        if (!retval)
                vma->vm_ops = &v9fs_file_vm_ops;

        return retval;
}

static int
v9fs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        struct v9fs_inode *v9inode;
        struct page *page = vmf->page;
        struct file *filp = vma->vm_file;
        struct inode *inode = filp->f_path.dentry->d_inode;


        P9_DPRINTK(P9_DEBUG_VFS, "page %p fid %lx\n",
                   page, (unsigned long)filp->private_data);

        v9inode = V9FS_I(inode);
        /* make sure the cache has finished storing the page */
        v9fs_fscache_wait_on_page_write(inode, page);
        BUG_ON(!v9inode->writeback_fid);
        lock_page(page);
        if (page->mapping != inode->i_mapping)
                goto out_unlock;

        return VM_FAULT_LOCKED;
out_unlock:
        unlock_page(page);
        return VM_FAULT_NOPAGE;
}

static ssize_t
v9fs_direct_read(struct file *filp, char __user *udata, size_t count,
                 loff_t *offsetp)
{
        loff_t size, offset;
        struct inode *inode;
        struct address_space *mapping;

        offset = *offsetp;
        mapping = filp->f_mapping;
        inode = mapping->host;
        if (!count)
                return 0;
        size = i_size_read(inode);
        if (offset < size)
                filemap_write_and_wait_range(mapping, offset,
                                             offset + count - 1);

        return v9fs_file_read(filp, udata, count, offsetp);
}

/**
 * v9fs_cached_file_read - read from a file
 * @filp: file pointer to read
 * @udata: user data buffer to read data into
 * @count: size of buffer
 * @offset: offset at which to read data
 *
 */
static ssize_t
v9fs_cached_file_read(struct file *filp, char __user *data, size_t count,
                      loff_t *offset)
{
        if (filp->f_flags & O_DIRECT)
                return v9fs_direct_read(filp, data, count, offset);
        return do_sync_read(filp, data, count, offset);
}

static ssize_t
v9fs_direct_write(struct file *filp, const char __user * data,
                  size_t count, loff_t *offsetp)
{
        loff_t offset;
        ssize_t retval;
        struct inode *inode;
        struct address_space *mapping;

        offset = *offsetp;
        mapping = filp->f_mapping;
        inode = mapping->host;
        if (!count)
                return 0;

        mutex_lock(&inode->i_mutex);
        retval = filemap_write_and_wait_range(mapping, offset,
                                              offset + count - 1);
        if (retval)
                goto err_out;
        /*
         * After a write we want buffered reads to be sure to go to disk to get
         * the new data.  We invalidate clean cached page from the region we're
         * about to write.  We do this *before* the write so that if we fail
         * here we fall back to buffered write
         */
        if (mapping->nrpages) {
                pgoff_t pg_start = offset >> PAGE_CACHE_SHIFT;
                pgoff_t pg_end   = (offset + count - 1) >> PAGE_CACHE_SHIFT;

                retval = invalidate_inode_pages2_range(mapping,
                                                        pg_start, pg_end);
                /*
                 * If a page can not be invalidated, fall back
                 * to buffered write.
                 */
                if (retval) {
                        if (retval == -EBUSY)
                                goto buff_write;
                        goto err_out;
                }
        }
        retval = v9fs_file_write(filp, data, count, offsetp);
err_out:
        mutex_unlock(&inode->i_mutex);
        return retval;

buff_write:
        mutex_unlock(&inode->i_mutex);
        return do_sync_write(filp, data, count, offsetp);
}

/**
 * v9fs_cached_file_write - write to a file
 * @filp: file pointer to write
 * @data: data buffer to write data from
 * @count: size of buffer
 * @offset: offset at which to write data
 *
 */
static ssize_t
v9fs_cached_file_write(struct file *filp, const char __user * data,
                       size_t count, loff_t *offset)
{

        if (filp->f_flags & O_DIRECT)
                return v9fs_direct_write(filp, data, count, offset);
        return do_sync_write(filp, data, count, offset);
}

static const struct vm_operations_struct v9fs_file_vm_ops = {
        .fault = filemap_fault,
        .page_mkwrite = v9fs_vm_page_mkwrite,
};


const struct file_operations v9fs_cached_file_operations = {
        .llseek = generic_file_llseek,
        .read = v9fs_cached_file_read,
        .write = v9fs_cached_file_write,
        .aio_read = generic_file_aio_read,
        .aio_write = generic_file_aio_write,
        .open = v9fs_file_open,
        .release = v9fs_dir_release,
        .lock = v9fs_file_lock,
        .mmap = v9fs_file_mmap,
        .fsync = v9fs_file_fsync,
};

const struct file_operations v9fs_cached_file_operations_dotl = {
        .llseek = generic_file_llseek,
        .read = v9fs_cached_file_read,
        .write = v9fs_cached_file_write,
        .aio_read = generic_file_aio_read,
        .aio_write = generic_file_aio_write,
        .open = v9fs_file_open,
        .release = v9fs_dir_release,
        .lock = v9fs_file_lock_dotl,
        .flock = v9fs_file_flock_dotl,
        .mmap = v9fs_file_mmap,
        .fsync = v9fs_file_fsync_dotl,
};

const struct file_operations v9fs_file_operations = {
        .llseek = generic_file_llseek,
        .read = v9fs_file_read,
        .write = v9fs_file_write,
        .open = v9fs_file_open,
        .release = v9fs_dir_release,
        .lock = v9fs_file_lock,
        .mmap = generic_file_readonly_mmap,
        .fsync = v9fs_file_fsync,
};

const struct file_operations v9fs_file_operations_dotl = {
        .llseek = generic_file_llseek,
        .read = v9fs_file_read,
        .write = v9fs_file_write,
        .open = v9fs_file_open,
        .release = v9fs_dir_release,
        .lock = v9fs_file_lock_dotl,
        .flock = v9fs_file_flock_dotl,
        .mmap = generic_file_readonly_mmap,
        .fsync = v9fs_file_fsync_dotl,
};