/*
   * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.

   * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.

   *
   * This copyrighted material is made available to anyone wishing to use,
   * modify, copy, or redistribute it subject to the terms and conditions

   * of the GNU General Public License version 2.

   */

  #include <linux/slab.h>
  #include <linux/spinlock.h>
  #include <linux/completion.h>
  #include <linux/buffer_head.h>
  #include <linux/pagemap.h>
  #include <linux/uio.h>
  #include <linux/blkdev.h>
  #include <linux/mm.h>

  #include <linux/mount.h>

  #include <linux/fs.h>

  #include <linux/gfs2_ondisk.h>

  #include <linux/ext2_fs.h>

  #include <linux/falloc.h>
  #include <linux/swap.h>

  #include <linux/crc32.h>

  #include <linux/writeback.h>

  #include <asm/uaccess.h>

  #include <linux/dlm.h>
  #include <linux/dlm_plock.h>

  
  #include "gfs2.h"

  #include "incore.h"

  #include "bmap.h"
  #include "dir.h"
  #include "glock.h"
  #include "glops.h"
  #include "inode.h"

  #include "log.h"
  #include "meta_io.h"

  #include "quota.h"
  #include "rgrp.h"
  #include "trans.h"

  #include "util.h"

  /**
   * gfs2_llseek - seek to a location in a file
   * @file: the file
   * @offset: the offset
   * @origin: Where to seek from (SEEK_SET, SEEK_CUR, or SEEK_END)
   *
   * SEEK_END requires the glock for the file because it references the
   * file's size.
   *
   * Returns: The new offset, or errno
   */
  
  static loff_t gfs2_llseek(struct file *file, loff_t offset, int origin)
  {

  	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);

  	struct gfs2_holder i_gh;
  	loff_t error;

  	switch (origin) {
  	case SEEK_END: /* These reference inode->i_size */
  	case SEEK_DATA:
  	case SEEK_HOLE:

  		error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY,
  					   &i_gh);
  		if (!error) {

  			error = generic_file_llseek(file, offset, origin);

  			gfs2_glock_dq_uninit(&i_gh);
  		}

  		break;
  	case SEEK_CUR:
  	case SEEK_SET:

  		error = generic_file_llseek(file, offset, origin);

  		break;
  	default:
  		error = -EINVAL;
  	}

  
  	return error;
  }

  /**

   * gfs2_readdir - Read directory entries from a directory

   * @file: The directory to read from
   * @dirent: Buffer for dirents
   * @filldir: Function used to do the copying
   *
   * Returns: errno
   */

  static int gfs2_readdir(struct file *file, void *dirent, filldir_t filldir)

  {

  	struct inode *dir = file->f_mapping->host;

  	struct gfs2_inode *dip = GFS2_I(dir);

  	struct gfs2_holder d_gh;

  	u64 offset = file->f_pos;

  	int error;

  	gfs2_holder_init(dip->i_gl, LM_ST_SHARED, 0, &d_gh);
  	error = gfs2_glock_nq(&d_gh);

  	if (error) {
  		gfs2_holder_uninit(&d_gh);
  		return error;
  	}

  	error = gfs2_dir_read(dir, &offset, dirent, filldir, &file->f_ra);

  
  	gfs2_glock_dq_uninit(&d_gh);

  	file->f_pos = offset;

  	return error;
  }

  /**
   * fsflags_cvt
   * @table: A table of 32 u32 flags
   * @val: a 32 bit value to convert
   *
   * This function can be used to convert between fsflags values and
   * GFS2's own flags values.
   *
   * Returns: the converted flags
   */
  static u32 fsflags_cvt(const u32 *table, u32 val)
  {
  	u32 res = 0;
  	while(val) {
  		if (val & 1)
  			res |= *table;
  		table++;
  		val >>= 1;
  	}
  	return res;
  }

  static const u32 fsflags_to_gfs2[32] = {
  	[3] = GFS2_DIF_SYNC,
  	[4] = GFS2_DIF_IMMUTABLE,
  	[5] = GFS2_DIF_APPENDONLY,
  	[7] = GFS2_DIF_NOATIME,
  	[12] = GFS2_DIF_EXHASH,

  	[14] = GFS2_DIF_INHERIT_JDATA,

  };

  static const u32 gfs2_to_fsflags[32] = {
  	[gfs2fl_Sync] = FS_SYNC_FL,
  	[gfs2fl_Immutable] = FS_IMMUTABLE_FL,
  	[gfs2fl_AppendOnly] = FS_APPEND_FL,
  	[gfs2fl_NoAtime] = FS_NOATIME_FL,
  	[gfs2fl_ExHash] = FS_INDEX_FL,

  	[gfs2fl_InheritJdata] = FS_JOURNAL_DATA_FL,

  };

  static int gfs2_get_flags(struct file *filp, u32 __user *ptr)

  {

  	struct inode *inode = filp->f_path.dentry->d_inode;

  	struct gfs2_inode *ip = GFS2_I(inode);

  	struct gfs2_holder gh;
  	int error;

  	u32 fsflags;

  	gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
  	error = gfs2_glock_nq(&gh);

  	if (error)
  		return error;

  	fsflags = fsflags_cvt(gfs2_to_fsflags, ip->i_diskflags);
  	if (!S_ISDIR(inode->i_mode) && ip->i_diskflags & GFS2_DIF_JDATA)

  		fsflags |= FS_JOURNAL_DATA_FL;

  	if (put_user(fsflags, ptr))

  		error = -EFAULT;

  	gfs2_glock_dq(&gh);

  	gfs2_holder_uninit(&gh);
  	return error;
  }

  void gfs2_set_inode_flags(struct inode *inode)
  {
  	struct gfs2_inode *ip = GFS2_I(inode);

  	unsigned int flags = inode->i_flags;

  	flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_NOSEC);
  	if ((ip->i_eattr == 0) && !is_sxid(inode->i_mode))
  		inode->i_flags |= S_NOSEC;

  	if (ip->i_diskflags & GFS2_DIF_IMMUTABLE)

  		flags |= S_IMMUTABLE;

  	if (ip->i_diskflags & GFS2_DIF_APPENDONLY)

  		flags |= S_APPEND;

  	if (ip->i_diskflags & GFS2_DIF_NOATIME)

  		flags |= S_NOATIME;

  	if (ip->i_diskflags & GFS2_DIF_SYNC)

  		flags |= S_SYNC;
  	inode->i_flags = flags;
  }

  /* Flags that can be set by user space */
  #define GFS2_FLAGS_USER_SET (GFS2_DIF_JDATA|			\

  			     GFS2_DIF_IMMUTABLE|		\
  			     GFS2_DIF_APPENDONLY|		\
  			     GFS2_DIF_NOATIME|			\
  			     GFS2_DIF_SYNC|			\
  			     GFS2_DIF_SYSTEM|			\

  			     GFS2_DIF_INHERIT_JDATA)
  
  /**
   * gfs2_set_flags - set flags on an inode
   * @inode: The inode
   * @flags: The flags to set
   * @mask: Indicates which flags are valid
   *
   */

  static int do_gfs2_set_flags(struct file *filp, u32 reqflags, u32 mask)

  {

  	struct inode *inode = filp->f_path.dentry->d_inode;

  	struct gfs2_inode *ip = GFS2_I(inode);
  	struct gfs2_sbd *sdp = GFS2_SB(inode);

  	struct buffer_head *bh;
  	struct gfs2_holder gh;
  	int error;

  	u32 new_flags, flags;

  	error = mnt_want_write_file(filp);

  	if (error)

  		return error;

  	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
  	if (error)
  		goto out_drop_write;

  	error = -EACCES;

  	if (!inode_owner_or_capable(inode))

  		goto out;
  
  	error = 0;

  	flags = ip->i_diskflags;

  	new_flags = (flags & ~mask) | (reqflags & mask);

  	if ((new_flags ^ flags) == 0)
  		goto out;
  
  	error = -EINVAL;
  	if ((new_flags ^ flags) & ~GFS2_FLAGS_USER_SET)
  		goto out;

  	error = -EPERM;
  	if (IS_IMMUTABLE(inode) && (new_flags & GFS2_DIF_IMMUTABLE))
  		goto out;
  	if (IS_APPEND(inode) && (new_flags & GFS2_DIF_APPENDONLY))
  		goto out;

  	if (((new_flags ^ flags) & GFS2_DIF_IMMUTABLE) &&

  	    !capable(CAP_LINUX_IMMUTABLE))

  		goto out;

  	if (!IS_IMMUTABLE(inode)) {

  		error = gfs2_permission(inode, MAY_WRITE);

  		if (error)
  			goto out;
  	}

  	if ((flags ^ new_flags) & GFS2_DIF_JDATA) {
  		if (flags & GFS2_DIF_JDATA)
  			gfs2_log_flush(sdp, ip->i_gl);
  		error = filemap_fdatawrite(inode->i_mapping);
  		if (error)
  			goto out;
  		error = filemap_fdatawait(inode->i_mapping);
  		if (error)
  			goto out;
  	}

  	error = gfs2_trans_begin(sdp, RES_DINODE, 0);

  	if (error)
  		goto out;

  	error = gfs2_meta_inode_buffer(ip, &bh);
  	if (error)
  		goto out_trans_end;

  	gfs2_trans_add_bh(ip->i_gl, bh, 1);

  	ip->i_diskflags = new_flags;

  	gfs2_dinode_out(ip, bh->b_data);

  	brelse(bh);

  	gfs2_set_inode_flags(inode);

  	gfs2_set_aops(inode);

  out_trans_end:
  	gfs2_trans_end(sdp);

  out:
  	gfs2_glock_dq_uninit(&gh);

  out_drop_write:

  	mnt_drop_write_file(filp);

  	return error;
  }

  static int gfs2_set_flags(struct file *filp, u32 __user *ptr)

  {

  	struct inode *inode = filp->f_path.dentry->d_inode;

  	u32 fsflags, gfsflags;

  	if (get_user(fsflags, ptr))

  		return -EFAULT;

  	gfsflags = fsflags_cvt(fsflags_to_gfs2, fsflags);

  	if (!S_ISDIR(inode->i_mode)) {
  		if (gfsflags & GFS2_DIF_INHERIT_JDATA)
  			gfsflags ^= (GFS2_DIF_JDATA | GFS2_DIF_INHERIT_JDATA);

  		return do_gfs2_set_flags(filp, gfsflags, ~0);
  	}
  	return do_gfs2_set_flags(filp, gfsflags, ~GFS2_DIF_JDATA);

  }

  static long gfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)

  {
  	switch(cmd) {

  	case FS_IOC_GETFLAGS:

  		return gfs2_get_flags(filp, (u32 __user *)arg);

  	case FS_IOC_SETFLAGS:

  		return gfs2_set_flags(filp, (u32 __user *)arg);

  	}
  	return -ENOTTY;
  }

  /**
   * gfs2_allocate_page_backing - Use bmap to allocate blocks
   * @page: The (locked) page to allocate backing for
   *
   * We try to allocate all the blocks required for the page in
   * one go. This might fail for various reasons, so we keep
   * trying until all the blocks to back this page are allocated.
   * If some of the blocks are already allocated, thats ok too.
   */
  
  static int gfs2_allocate_page_backing(struct page *page)
  {
  	struct inode *inode = page->mapping->host;
  	struct buffer_head bh;
  	unsigned long size = PAGE_CACHE_SIZE;
  	u64 lblock = page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
  
  	do {
  		bh.b_state = 0;
  		bh.b_size = size;

  		gfs2_block_map(inode, lblock, &bh, 1);

  		if (!buffer_mapped(&bh))
  			return -EIO;
  		size -= bh.b_size;
  		lblock += (bh.b_size >> inode->i_blkbits);
  	} while(size > 0);
  	return 0;
  }
  
  /**
   * gfs2_page_mkwrite - Make a shared, mmap()ed, page writable
   * @vma: The virtual memory area
   * @page: The page which is about to become writable
   *
   * When the page becomes writable, we need to ensure that we have
   * blocks allocated on disk to back that page.
   */

  static int gfs2_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)

  {

  	struct page *page = vmf->page;

  	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
  	struct gfs2_inode *ip = GFS2_I(inode);
  	struct gfs2_sbd *sdp = GFS2_SB(inode);
  	unsigned long last_index;

  	u64 pos = page->index << PAGE_CACHE_SHIFT;

  	unsigned int data_blocks, ind_blocks, rblocks;

  	struct gfs2_holder gh;

  	struct gfs2_qadata *qa;

  	loff_t size;

  	int ret;

  	/* Wait if fs is frozen. This is racy so we check again later on
  	 * and retry if the fs has been frozen after the page lock has
  	 * been acquired
  	 */
  	vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);

  	gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
  	ret = gfs2_glock_nq(&gh);

  	if (ret)
  		goto out;

  	set_bit(GLF_DIRTY, &ip->i_gl->gl_flags);
  	set_bit(GIF_SW_PAGED, &ip->i_flags);

  	if (!gfs2_write_alloc_required(ip, pos, PAGE_CACHE_SIZE)) {
  		lock_page(page);
  		if (!PageUptodate(page) || page->mapping != inode->i_mapping) {
  			ret = -EAGAIN;
  			unlock_page(page);
  		}

  		goto out_unlock;

  	}

  	ret = -ENOMEM;

  	qa = gfs2_qadata_get(ip);
  	if (qa == NULL)

  		goto out_unlock;

  	ret = gfs2_quota_lock_check(ip);

  	if (ret)
  		goto out_alloc_put;

  	gfs2_write_calc_reserv(ip, PAGE_CACHE_SIZE, &data_blocks, &ind_blocks);

  	ret = gfs2_inplace_reserve(ip, data_blocks + ind_blocks);

  	if (ret)
  		goto out_quota_unlock;
  
  	rblocks = RES_DINODE + ind_blocks;
  	if (gfs2_is_jdata(ip))
  		rblocks += data_blocks ? data_blocks : 1;

  	if (ind_blocks || data_blocks) {

  		rblocks += RES_STATFS + RES_QUOTA;

  		rblocks += gfs2_rg_blocks(ip);

  	}

  	ret = gfs2_trans_begin(sdp, rblocks, 0);
  	if (ret)
  		goto out_trans_fail;
  
  	lock_page(page);
  	ret = -EINVAL;

  	size = i_size_read(inode);
  	last_index = (size - 1) >> PAGE_CACHE_SHIFT;
  	/* Check page index against inode size */
  	if (size == 0 || (page->index > last_index))
  		goto out_trans_end;
  
  	ret = -EAGAIN;
  	/* If truncated, we must retry the operation, we may have raced
  	 * with the glock demotion code.
  	 */
  	if (!PageUptodate(page) || page->mapping != inode->i_mapping)
  		goto out_trans_end;
  
  	/* Unstuff, if required, and allocate backing blocks for page */

  	ret = 0;

  	if (gfs2_is_stuffed(ip))

  		ret = gfs2_unstuff_dinode(ip, page);

  	if (ret == 0)
  		ret = gfs2_allocate_page_backing(page);

  out_trans_end:
  	if (ret)
  		unlock_page(page);

  	gfs2_trans_end(sdp);
  out_trans_fail:
  	gfs2_inplace_release(ip);
  out_quota_unlock:
  	gfs2_quota_unlock(ip);
  out_alloc_put:

  	gfs2_qadata_put(ip);

  out_unlock:
  	gfs2_glock_dq(&gh);
  out:
  	gfs2_holder_uninit(&gh);

  	if (ret == 0) {
  		set_page_dirty(page);
  		/* This check must be post dropping of transaction lock */
  		if (inode->i_sb->s_frozen == SB_UNFROZEN) {
  			wait_on_page_writeback(page);
  		} else {
  			ret = -EAGAIN;
  			unlock_page(page);
  		}
  	}
  	return block_page_mkwrite_return(ret);

  }

  static const struct vm_operations_struct gfs2_vm_ops = {

  	.fault = filemap_fault,
  	.page_mkwrite = gfs2_page_mkwrite,
  };

  /**
   * gfs2_mmap -
   * @file: The file to map
   * @vma: The VMA which described the mapping
   *

   * There is no need to get a lock here unless we should be updating
   * atime. We ignore any locking errors since the only consequence is
   * a missed atime update (which will just be deferred until later).
   *
   * Returns: 0

   */
  
  static int gfs2_mmap(struct file *file, struct vm_area_struct *vma)
  {

  	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);

  	if (!(file->f_flags & O_NOATIME) &&
  	    !IS_NOATIME(&ip->i_inode)) {

  		struct gfs2_holder i_gh;
  		int error;

  		gfs2_holder_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);

  		error = gfs2_glock_nq(&i_gh);

  		if (error == 0) {
  			file_accessed(file);
  			gfs2_glock_dq(&i_gh);
  		}
  		gfs2_holder_uninit(&i_gh);
  		if (error)
  			return error;

  	}

  	vma->vm_ops = &gfs2_vm_ops;

  	vma->vm_flags |= VM_CAN_NONLINEAR;

  	return 0;

  }
  
  /**
   * gfs2_open - open a file
   * @inode: the inode to open
   * @file: the struct file for this opening
   *
   * Returns: errno
   */
  
  static int gfs2_open(struct inode *inode, struct file *file)
  {

  	struct gfs2_inode *ip = GFS2_I(inode);

  	struct gfs2_holder i_gh;
  	struct gfs2_file *fp;
  	int error;

  	fp = kzalloc(sizeof(struct gfs2_file), GFP_KERNEL);
  	if (!fp)
  		return -ENOMEM;

  	mutex_init(&fp->f_fl_mutex);

  	gfs2_assert_warn(GFS2_SB(inode), !file->private_data);

  	file->private_data = fp;

  	if (S_ISREG(ip->i_inode.i_mode)) {

  		error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY,
  					   &i_gh);
  		if (error)
  			goto fail;
  
  		if (!(file->f_flags & O_LARGEFILE) &&

  		    i_size_read(inode) > MAX_NON_LFS) {

  			error = -EOVERFLOW;

  			goto fail_gunlock;
  		}

  		gfs2_glock_dq_uninit(&i_gh);
  	}
  
  	return 0;

  fail_gunlock:

  	gfs2_glock_dq_uninit(&i_gh);

  fail:

  	file->private_data = NULL;

  	kfree(fp);

  	return error;
  }
  
  /**
   * gfs2_close - called to close a struct file
   * @inode: the inode the struct file belongs to
   * @file: the struct file being closed
   *
   * Returns: errno
   */
  
  static int gfs2_close(struct inode *inode, struct file *file)
  {

  	struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;

  	struct gfs2_file *fp;

  	fp = file->private_data;
  	file->private_data = NULL;

  
  	if (gfs2_assert_warn(sdp, fp))
  		return -EIO;
  
  	kfree(fp);
  
  	return 0;
  }
  
  /**
   * gfs2_fsync - sync the dirty data for a file (across the cluster)

   * @file: the file that points to the dentry
   * @start: the start position in the file to sync
   * @end: the end position in the file to sync

   * @datasync: set if we can ignore timestamp changes

   *

   * We split the data flushing here so that we don't wait for the data
   * until after we've also sent the metadata to disk. Note that for
   * data=ordered, we will write & wait for the data at the log flush
   * stage anyway, so this is unlikely to make much of a difference
   * except in the data=writeback case.
   *
   * If the fdatawrite fails due to any reason except -EIO, we will
   * continue the remainder of the fsync, although we'll still report
   * the error at the end. This is to match filemap_write_and_wait_range()
   * behaviour.

   *

   * Returns: errno
   */

  static int gfs2_fsync(struct file *file, loff_t start, loff_t end,
  		      int datasync)

  {

  	struct address_space *mapping = file->f_mapping;
  	struct inode *inode = mapping->host;

  	int sync_state = inode->i_state & (I_DIRTY_SYNC|I_DIRTY_DATASYNC);

  	struct gfs2_inode *ip = GFS2_I(inode);

  	int ret = 0, ret1 = 0;

  	if (mapping->nrpages) {
  		ret1 = filemap_fdatawrite_range(mapping, start, end);
  		if (ret1 == -EIO)
  			return ret1;
  	}

  	if (datasync)
  		sync_state &= ~I_DIRTY_SYNC;

  	if (sync_state) {
  		ret = sync_inode_metadata(inode, 1);

  		if (ret)

  			return ret;

  		if (gfs2_is_jdata(ip))
  			filemap_write_and_wait(mapping);

  		gfs2_ail_flush(ip->i_gl, 1);

  	}

  	if (mapping->nrpages)
  		ret = filemap_fdatawait_range(mapping, start, end);
  
  	return ret ? ret : ret1;

  }

  /**
   * gfs2_file_aio_write - Perform a write to a file
   * @iocb: The io context
   * @iov: The data to write
   * @nr_segs: Number of @iov segments
   * @pos: The file position
   *
   * We have to do a lock/unlock here to refresh the inode size for
   * O_APPEND writes, otherwise we can land up writing at the wrong
   * offset. There is still a race, but provided the app is using its
   * own file locking, this will make O_APPEND work as expected.
   *
   */
  
  static ssize_t gfs2_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
  				   unsigned long nr_segs, loff_t pos)
  {
  	struct file *file = iocb->ki_filp;
  
  	if (file->f_flags & O_APPEND) {
  		struct dentry *dentry = file->f_dentry;
  		struct gfs2_inode *ip = GFS2_I(dentry->d_inode);
  		struct gfs2_holder gh;
  		int ret;
  
  		ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
  		if (ret)
  			return ret;
  		gfs2_glock_dq_uninit(&gh);
  	}
  
  	return generic_file_aio_write(iocb, iov, nr_segs, pos);
  }

  static int fallocate_chunk(struct inode *inode, loff_t offset, loff_t len,
  			   int mode)
  {
  	struct gfs2_inode *ip = GFS2_I(inode);
  	struct buffer_head *dibh;
  	int error;

  	unsigned int nr_blks;
  	sector_t lblock = offset >> inode->i_blkbits;

  
  	error = gfs2_meta_inode_buffer(ip, &dibh);
  	if (unlikely(error))

  		return error;

  
  	gfs2_trans_add_bh(ip->i_gl, dibh, 1);
  
  	if (gfs2_is_stuffed(ip)) {
  		error = gfs2_unstuff_dinode(ip, NULL);
  		if (unlikely(error))
  			goto out;
  	}

  	while (len) {
  		struct buffer_head bh_map = { .b_state = 0, .b_blocknr = 0 };
  		bh_map.b_size = len;
  		set_buffer_zeronew(&bh_map);

  		error = gfs2_block_map(inode, lblock, &bh_map, 1);
  		if (unlikely(error))
  			goto out;
  		len -= bh_map.b_size;
  		nr_blks = bh_map.b_size >> inode->i_blkbits;
  		lblock += nr_blks;
  		if (!buffer_new(&bh_map))
  			continue;
  		if (unlikely(!buffer_zeronew(&bh_map))) {
  			error = -EIO;

  			goto out;

  		}

  	}

  	if (offset + len > inode->i_size && !(mode & FALLOC_FL_KEEP_SIZE))
  		i_size_write(inode, offset + len);

  	mark_inode_dirty(inode);

  out:

  	brelse(dibh);

  	return error;
  }
  
  static void calc_max_reserv(struct gfs2_inode *ip, loff_t max, loff_t *len,
  			    unsigned int *data_blocks, unsigned int *ind_blocks)
  {
  	const struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);

  	unsigned int max_blocks = ip->i_rgd->rd_free_clone;

  	unsigned int tmp, max_data = max_blocks - 3 * (sdp->sd_max_height - 1);
  
  	for (tmp = max_data; tmp > sdp->sd_diptrs;) {
  		tmp = DIV_ROUND_UP(tmp, sdp->sd_inptrs);
  		max_data -= tmp;
  	}
  	/* This calculation isn't the exact reverse of gfs2_write_calc_reserve,
  	   so it might end up with fewer data blocks */
  	if (max_data <= *data_blocks)
  		return;
  	*data_blocks = max_data;
  	*ind_blocks = max_blocks - max_data;
  	*len = ((loff_t)max_data - 3) << sdp->sd_sb.sb_bsize_shift;
  	if (*len > max) {
  		*len = max;
  		gfs2_write_calc_reserv(ip, max, data_blocks, ind_blocks);
  	}
  }
  
  static long gfs2_fallocate(struct file *file, int mode, loff_t offset,
  			   loff_t len)
  {
  	struct inode *inode = file->f_path.dentry->d_inode;
  	struct gfs2_sbd *sdp = GFS2_SB(inode);
  	struct gfs2_inode *ip = GFS2_I(inode);
  	unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
  	loff_t bytes, max_bytes;

  	struct gfs2_qadata *qa;

  	int error;

  	const loff_t pos = offset;
  	const loff_t count = len;

  	loff_t bsize_mask = ~((loff_t)sdp->sd_sb.sb_bsize - 1);

  	loff_t next = (offset + len - 1) >> sdp->sd_sb.sb_bsize_shift;

  	loff_t max_chunk_size = UINT_MAX & bsize_mask;

  	next = (next + 1) << sdp->sd_sb.sb_bsize_shift;
  
  	/* We only support the FALLOC_FL_KEEP_SIZE mode */
  	if (mode & ~FALLOC_FL_KEEP_SIZE)
  		return -EOPNOTSUPP;

  	offset &= bsize_mask;

  
  	len = next - offset;
  	bytes = sdp->sd_max_rg_data * sdp->sd_sb.sb_bsize / 2;
  	if (!bytes)
  		bytes = UINT_MAX;

  	bytes &= bsize_mask;
  	if (bytes == 0)
  		bytes = sdp->sd_sb.sb_bsize;

  
  	gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
  	error = gfs2_glock_nq(&ip->i_gh);
  	if (unlikely(error))
  		goto out_uninit;
  
  	if (!gfs2_write_alloc_required(ip, offset, len))
  		goto out_unlock;
  
  	while (len > 0) {
  		if (len < bytes)
  			bytes = len;

  		qa = gfs2_qadata_get(ip);
  		if (!qa) {

  			error = -ENOMEM;
  			goto out_unlock;
  		}
  
  		error = gfs2_quota_lock_check(ip);
  		if (error)
  			goto out_alloc_put;
  
  retry:
  		gfs2_write_calc_reserv(ip, bytes, &data_blocks, &ind_blocks);

  		error = gfs2_inplace_reserve(ip, data_blocks + ind_blocks);

  		if (error) {
  			if (error == -ENOSPC && bytes > sdp->sd_sb.sb_bsize) {
  				bytes >>= 1;

  				bytes &= bsize_mask;
  				if (bytes == 0)
  					bytes = sdp->sd_sb.sb_bsize;

  				goto retry;
  			}
  			goto out_qunlock;
  		}
  		max_bytes = bytes;

  		calc_max_reserv(ip, (len > max_chunk_size)? max_chunk_size: len,
  				&max_bytes, &data_blocks, &ind_blocks);

  
  		rblocks = RES_DINODE + ind_blocks + RES_STATFS + RES_QUOTA +

  			  RES_RG_HDR + gfs2_rg_blocks(ip);

  		if (gfs2_is_jdata(ip))
  			rblocks += data_blocks ? data_blocks : 1;
  
  		error = gfs2_trans_begin(sdp, rblocks,
  					 PAGE_CACHE_SIZE/sdp->sd_sb.sb_bsize);
  		if (error)
  			goto out_trans_fail;
  
  		error = fallocate_chunk(inode, offset, max_bytes, mode);
  		gfs2_trans_end(sdp);
  
  		if (error)
  			goto out_trans_fail;
  
  		len -= max_bytes;
  		offset += max_bytes;
  		gfs2_inplace_release(ip);
  		gfs2_quota_unlock(ip);

  		gfs2_qadata_put(ip);

  	}

  
  	if (error == 0)
  		error = generic_write_sync(file, pos, count);

  	goto out_unlock;
  
  out_trans_fail:
  	gfs2_inplace_release(ip);
  out_qunlock:
  	gfs2_quota_unlock(ip);
  out_alloc_put:

  	gfs2_qadata_put(ip);

  out_unlock:
  	gfs2_glock_dq(&ip->i_gh);
  out_uninit:
  	gfs2_holder_uninit(&ip->i_gh);
  	return error;
  }

  #ifdef CONFIG_GFS2_FS_LOCKING_DLM

  /**

   * gfs2_setlease - acquire/release a file lease
   * @file: the file pointer
   * @arg: lease type
   * @fl: file lock
   *

   * We don't currently have a way to enforce a lease across the whole
   * cluster; until we do, disable leases (by just returning -EINVAL),
   * unless the administrator has requested purely local locking.
   *

   * Locking: called under lock_flocks
   *

   * Returns: errno
   */
  
  static int gfs2_setlease(struct file *file, long arg, struct file_lock **fl)
  {

  	return -EINVAL;

  }

  /**

   * gfs2_lock - acquire/release a posix lock on a file
   * @file: the file pointer
   * @cmd: either modify or retrieve lock state, possibly wait
   * @fl: type and range of lock
   *
   * Returns: errno
   */
  
  static int gfs2_lock(struct file *file, int cmd, struct file_lock *fl)
  {

  	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);
  	struct gfs2_sbd *sdp = GFS2_SB(file->f_mapping->host);

  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;

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

  	if (__mandatory_lock(&ip->i_inode) && fl->fl_type != F_UNLCK)

  		return -ENOLCK;

  	if (cmd == F_CANCELLK) {
  		/* Hack: */
  		cmd = F_SETLK;
  		fl->fl_type = F_UNLCK;
  	}

  	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
  		return -EIO;

  	if (IS_GETLK(cmd))

  		return dlm_posix_get(ls->ls_dlm, ip->i_no_addr, file, fl);

  	else if (fl->fl_type == F_UNLCK)

  		return dlm_posix_unlock(ls->ls_dlm, ip->i_no_addr, file, fl);

  	else

  		return dlm_posix_lock(ls->ls_dlm, ip->i_no_addr, file, cmd, fl);

  }

  static int do_flock(struct file *file, int cmd, struct file_lock *fl)
  {

  	struct gfs2_file *fp = file->private_data;

  	struct gfs2_holder *fl_gh = &fp->f_fl_gh;

  	struct gfs2_inode *ip = GFS2_I(file->f_path.dentry->d_inode);

  	struct gfs2_glock *gl;
  	unsigned int state;
  	int flags;
  	int error = 0;
  
  	state = (fl->fl_type == F_WRLCK) ? LM_ST_EXCLUSIVE : LM_ST_SHARED;

  	flags = (IS_SETLKW(cmd) ? 0 : LM_FLAG_TRY) | GL_EXACT | GL_NOCACHE;

  	mutex_lock(&fp->f_fl_mutex);

  
  	gl = fl_gh->gh_gl;
  	if (gl) {
  		if (fl_gh->gh_state == state)
  			goto out;

  		flock_lock_file_wait(file,

  				     &(struct file_lock){.fl_type = F_UNLCK});

  		gfs2_glock_dq_wait(fl_gh);
  		gfs2_holder_reinit(state, flags, fl_gh);

  	} else {

  		error = gfs2_glock_get(GFS2_SB(&ip->i_inode), ip->i_no_addr,
  				       &gfs2_flock_glops, CREATE, &gl);

  		if (error)
  			goto out;

  		gfs2_holder_init(gl, state, flags, fl_gh);
  		gfs2_glock_put(gl);

  	}

  	error = gfs2_glock_nq(fl_gh);
  	if (error) {
  		gfs2_holder_uninit(fl_gh);
  		if (error == GLR_TRYFAILED)
  			error = -EAGAIN;
  	} else {
  		error = flock_lock_file_wait(file, fl);

  		gfs2_assert_warn(GFS2_SB(&ip->i_inode), !error);

  	}

  out:

  	mutex_unlock(&fp->f_fl_mutex);

  	return error;
  }
  
  static void do_unflock(struct file *file, struct file_lock *fl)
  {

  	struct gfs2_file *fp = file->private_data;

  	struct gfs2_holder *fl_gh = &fp->f_fl_gh;

  	mutex_lock(&fp->f_fl_mutex);

  	flock_lock_file_wait(file, fl);

  	if (fl_gh->gh_gl) {
  		gfs2_glock_dq_wait(fl_gh);
  		gfs2_holder_uninit(fl_gh);
  	}

  	mutex_unlock(&fp->f_fl_mutex);

  }
  
  /**
   * gfs2_flock - acquire/release a flock lock on a file
   * @file: the file pointer
   * @cmd: either modify or retrieve lock state, possibly wait
   * @fl: type and range of lock
   *
   * Returns: errno
   */
  
  static int gfs2_flock(struct file *file, int cmd, struct file_lock *fl)
  {

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

  	if (fl->fl_type & LOCK_MAND)
  		return -EOPNOTSUPP;

  	if (fl->fl_type == F_UNLCK) {
  		do_unflock(file, fl);
  		return 0;

  	} else {

  		return do_flock(file, cmd, fl);

  	}

  }

  const struct file_operations gfs2_file_fops = {

  	.llseek		= gfs2_llseek,

  	.read		= do_sync_read,

  	.aio_read	= generic_file_aio_read,

  	.write		= do_sync_write,

  	.aio_write	= gfs2_file_aio_write,

  	.unlocked_ioctl	= gfs2_ioctl,
  	.mmap		= gfs2_mmap,
  	.open		= gfs2_open,
  	.release	= gfs2_close,
  	.fsync		= gfs2_fsync,
  	.lock		= gfs2_lock,

  	.flock		= gfs2_flock,
  	.splice_read	= generic_file_splice_read,
  	.splice_write	= generic_file_splice_write,

  	.setlease	= gfs2_setlease,

  	.fallocate	= gfs2_fallocate,

  };

  const struct file_operations gfs2_dir_fops = {

  	.readdir	= gfs2_readdir,
  	.unlocked_ioctl	= gfs2_ioctl,
  	.open		= gfs2_open,
  	.release	= gfs2_close,
  	.fsync		= gfs2_fsync,
  	.lock		= gfs2_lock,
  	.flock		= gfs2_flock,

  	.llseek		= default_llseek,

  };

  #endif /* CONFIG_GFS2_FS_LOCKING_DLM */

  const struct file_operations gfs2_file_fops_nolock = {

  	.llseek		= gfs2_llseek,
  	.read		= do_sync_read,
  	.aio_read	= generic_file_aio_read,
  	.write		= do_sync_write,

  	.aio_write	= gfs2_file_aio_write,

  	.unlocked_ioctl	= gfs2_ioctl,
  	.mmap		= gfs2_mmap,
  	.open		= gfs2_open,
  	.release	= gfs2_close,
  	.fsync		= gfs2_fsync,
  	.splice_read	= generic_file_splice_read,
  	.splice_write	= generic_file_splice_write,

  	.setlease	= generic_setlease,

  	.fallocate	= gfs2_fallocate,

  };

  const struct file_operations gfs2_dir_fops_nolock = {

  	.readdir	= gfs2_readdir,
  	.unlocked_ioctl	= gfs2_ioctl,
  	.open		= gfs2_open,
  	.release	= gfs2_close,
  	.fsync		= gfs2_fsync,

  	.llseek		= default_llseek,

  };