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/*

 *  file.c

 *

 *  Copyright (C) 1995, 1996, 1997 by Paal-Kr. Engstad and Volker Lendecke

 *  Copyright (C) 1997 by Volker Lendecke

 *

 *  Please add a note about your changes to smbfs in the ChangeLog file.

 */

#include <linux/sched.h>

#include <linux/kernel.h>

#include <linux/errno.h>

#include <linux/fcntl.h>

#include <linux/stat.h>

#include <linux/mm.h>

#include <linux/slab.h>

#include <linux/pagemap.h>

#include <linux/smp_lock.h>

#include <asm/uaccess.h>

#include <asm/system.h>

#include <linux/smbno.h>

#include <linux/smb_fs.h>

#include "smb_debug.h"

#include "proto.h"

static int

smb_fsync(struct file *file, struct dentry * dentry, int datasync)

{

        struct smb_sb_info *server = server_from_dentry(dentry);

        int result;

        VERBOSE("sync file %s/%s\n", DENTRY_PATH(dentry));

        /*

         * The VFS will writepage() all dirty pages for us, but we

         * should send a SMBflush to the server, letting it know that

         * we want things synchronized with actual storage.

         *

         * Note: this function requires all pages to have been written already

         *       (should be ok with writepage_sync)

         */

        smb_lock_server(server);

        result = smb_proc_flush(server, dentry->d_inode->u.smbfs_i.fileid);

        smb_unlock_server(server);

        return result;

}

/*

 * Read a page synchronously.

 */

static int

smb_readpage_sync(struct dentry *dentry, struct page *page)

{

        char *buffer = kmap(page);

        loff_t offset = (loff_t)page->index << PAGE_CACHE_SHIFT;

        struct smb_sb_info *server = server_from_dentry(dentry);

        unsigned int rsize = smb_get_rsize(server);

        int count = PAGE_SIZE;

        int result;

        VERBOSE("file %s/%s, count=%d@%ld, rsize=%d\n",

                DENTRY_PATH(dentry), count, offset, rsize);

        result = smb_open(dentry, SMB_O_RDONLY);

        if (result < 0) {

                PARANOIA("%s/%s open failed, error=%d\n",

                         DENTRY_PATH(dentry), result);

                goto io_error;

        }

        do {

                if (count < rsize)

                        rsize = count;

                result = server->ops->read(dentry->d_inode,offset,rsize,buffer);

                if (result < 0)

                        goto io_error;

                count -= result;

                offset += result;

                buffer += result;

                dentry->d_inode->i_atime = CURRENT_TIME;

                if (result < rsize)

                        break;

        } while (count);

        memset(buffer, 0, count);

        flush_dcache_page(page);

        SetPageUptodate(page);

        result = 0;

io_error:

        kunmap(page);

        UnlockPage(page);

        return result;

}

/*

 * We are called with the page locked and we unlock it when done.

 */

static int

smb_readpage(struct file *file, struct page *page)

{

        int             error;

        struct dentry  *dentry = file->f_dentry;

        get_page(page);

        error = smb_readpage_sync(dentry, page);

        put_page(page);

        return error;

}

/*

 * Write a page synchronously.

 * Offset is the data offset within the page.

 */

static int

smb_writepage_sync(struct inode *inode, struct page *page,

                   unsigned long pageoffset, unsigned int count)

{

        loff_t offset;

        char *buffer = kmap(page) + pageoffset;

        struct smb_sb_info *server = server_from_inode(inode);

        unsigned int wsize = smb_get_wsize(server);

        int result, written = 0;

        offset = ((loff_t)page->index << PAGE_CACHE_SHIFT) + pageoffset;

        VERBOSE("file ino=%ld, fileid=%d, count=%d@%Ld, wsize=%d\n",

                inode->i_ino, inode->u.smbfs_i.fileid, count, offset, wsize);

        do {

                if (count < wsize)

                        wsize = count;

                result = server->ops->write(inode, offset, wsize, buffer);

                if (result < 0) {

                        PARANOIA("failed write, wsize=%d, result=%d\n",

                                 wsize, result);

                        break;

                }

                /* N.B. what if result < wsize?? */

#ifdef SMBFS_PARANOIA

                if (result < wsize)

                        PARANOIA("short write, wsize=%d, result=%d\n",

                                 wsize, result);

#endif

                buffer += wsize;

                offset += wsize;

                written += wsize;

                count -= wsize;

                /*

                 * Update the inode now rather than waiting for a refresh.

                 */

                inode->i_mtime = inode->i_atime = CURRENT_TIME;

                inode->u.smbfs_i.flags |= SMB_F_LOCALWRITE;

                if (offset > inode->i_size)

                        inode->i_size = offset;

        } while (count);

        kunmap(page);

        return written ? written : result;

}

/*

 * Write a page to the server. This will be used for NFS swapping only

 * (for now), and we currently do this synchronously only.

 *

 * We are called with the page locked and we unlock it when done.

 */

static int

smb_writepage(struct page *page)

{

        struct address_space *mapping = page->mapping;

        struct inode *inode;

        unsigned long end_index;

        unsigned offset = PAGE_CACHE_SIZE;

        int err;

        if (!mapping)

                BUG();

        inode = mapping->host;

        if (!inode)

                BUG();

        end_index = inode->i_size >> PAGE_CACHE_SHIFT;

        /* easy case */

        if (page->index < end_index)

                goto do_it;

        /* things got complicated... */

        offset = inode->i_size & (PAGE_CACHE_SIZE-1);

        /* OK, are we completely out? */

        if (page->index >= end_index+1 || !offset)

                return -EIO;

do_it:

        get_page(page);

        err = smb_writepage_sync(inode, page, 0, offset);

        SetPageUptodate(page);

        UnlockPage(page);

        put_page(page);

        return err;

}

static int

smb_updatepage(struct file *file, struct page *page, unsigned long offset,

               unsigned int count)

{

        struct dentry *dentry = file->f_dentry;

        DEBUG1("(%s/%s %d@%ld)\n", DENTRY_PATH(dentry),

               count, (page->index << PAGE_CACHE_SHIFT)+offset);

        return smb_writepage_sync(dentry->d_inode, page, offset, count);

}

static ssize_t

smb_file_read(struct file * file, char * buf, size_t count, loff_t *ppos)

{

        struct dentry * dentry = file->f_dentry;

        ssize_t status;

        VERBOSE("file %s/%s, count=%lu@%lu\n", DENTRY_PATH(dentry),

                (unsigned long) count, (unsigned long) *ppos);

        status = smb_revalidate_inode(dentry);

        if (status) {

                PARANOIA("%s/%s validation failed, error=%Zd\n",

                         DENTRY_PATH(dentry), status);

                goto out;

        }

        VERBOSE("before read, size=%ld, flags=%x, atime=%ld\n",

                (long)dentry->d_inode->i_size,

                dentry->d_inode->i_flags, dentry->d_inode->i_atime);

        status = generic_file_read(file, buf, count, ppos);

out:

        return status;

}

static int

smb_file_mmap(struct file * file, struct vm_area_struct * vma)

{

        struct dentry * dentry = file->f_dentry;

        int     status;

        VERBOSE("file %s/%s, address %lu - %lu\n",

                DENTRY_PATH(dentry), vma->vm_start, vma->vm_end);

        status = smb_revalidate_inode(dentry);

        if (status) {

                PARANOIA("%s/%s validation failed, error=%d\n",

                         DENTRY_PATH(dentry), status);

                goto out;

        }

        status = generic_file_mmap(file, vma);

out:

        return status;

}

/*

 * This does the "real" work of the write. The generic routine has

 * allocated the page, locked it, done all the page alignment stuff

 * calculations etc. Now we should just copy the data from user

 * space and write it back to the real medium..

 *

 * If the writer ends up delaying the write, the writer needs to

 * increment the page use counts until he is done with the page.

 */

static int smb_prepare_write(struct file *file, struct page *page,

                             unsigned offset, unsigned to)

{

        return 0;

}

static int smb_commit_write(struct file *file, struct page *page,

                            unsigned offset, unsigned to)

{

        int status;

        status = -EFAULT;

        lock_kernel();

        status = smb_updatepage(file, page, offset, to-offset);

        unlock_kernel();

        return status;

}

struct address_space_operations smb_file_aops = {

        readpage: smb_readpage,

        writepage: smb_writepage,

        prepare_write: smb_prepare_write,

        commit_write: smb_commit_write

};

/*

 * Write to a file (through the page cache).

 */

static ssize_t

smb_file_write(struct file *file, const char *buf, size_t count, loff_t *ppos)

{

        struct dentry * dentry = file->f_dentry;

        ssize_t result;

        VERBOSE("file %s/%s, count=%lu@%lu\n",

                DENTRY_PATH(dentry),

                (unsigned long) count, (unsigned long) *ppos);

        result = smb_revalidate_inode(dentry);

        if (result) {

                PARANOIA("%s/%s validation failed, error=%Zd\n",

                         DENTRY_PATH(dentry), result);

                goto out;

        }

        result = smb_open(dentry, SMB_O_WRONLY);

        if (result)

                goto out;

        if (count > 0) {

                result = generic_file_write(file, buf, count, ppos);

                VERBOSE("pos=%ld, size=%ld, mtime=%ld, atime=%ld\n",

                        (long) file->f_pos, (long) dentry->d_inode->i_size,

                        dentry->d_inode->i_mtime, dentry->d_inode->i_atime);

        }

out:

        return result;

}

static int

smb_file_open(struct inode *inode, struct file * file)

{

        int result;

        struct dentry *dentry = file->f_dentry;

        int smb_mode = (file->f_mode & O_ACCMODE) - 1;

        lock_kernel();

        result = smb_open(dentry, smb_mode);

        if (result)

                goto out;

        inode->u.smbfs_i.openers++;

out:

        unlock_kernel();

        return 0;

}

static int

smb_file_release(struct inode *inode, struct file * file)

{

        lock_kernel();

        if (!--inode->u.smbfs_i.openers) {

                /* We must flush any dirty pages now as we won't be able to

                   write anything after close. mmap can trigger this.

                   "openers" should perhaps include mmap'ers ... */

                filemap_fdatasync(inode->i_mapping);

                filemap_fdatawait(inode->i_mapping);

                smb_close(inode);

        }

        unlock_kernel();

        return 0;

}

/*

 * Check whether the required access is compatible with

 * an inode's permission. SMB doesn't recognize superuser

 * privileges, so we need our own check for this.

 */

static int

smb_file_permission(struct inode *inode, int mask)

{

        int mode = inode->i_mode;

        int error = 0;

        VERBOSE("mode=%x, mask=%x\n", mode, mask);

        /* Look at user permissions */

        mode >>= 6;

        if ((mode & 7 & mask) != mask)

                error = -EACCES;

        return error;

}

struct file_operations smb_file_operations =

{

        llseek:         generic_file_llseek,

        read:           smb_file_read,

        write:          smb_file_write,

        ioctl:          smb_ioctl,

        mmap:           smb_file_mmap,

        open:           smb_file_open,

        release:        smb_file_release,

        fsync:          smb_fsync,

};

struct inode_operations smb_file_inode_operations =

{

        permission:     smb_file_permission,

        revalidate:     smb_revalidate_inode,

        setattr:        smb_notify_change,

};