/*
   *  linux/fs/nfs/file.c
   *
   *  Copyright (C) 1992  Rick Sladkey
   *
   *  Changes Copyright (C) 1994 by Florian La Roche
   *   - Do not copy data too often around in the kernel.
   *   - In nfs_file_read the return value of kmalloc wasn't checked.
   *   - Put in a better version of read look-ahead buffering. Original idea
   *     and implementation by Wai S Kok elekokws@ee.nus.sg.
   *
   *  Expire cache on write to a file by Wai S Kok (Oct 1994).
   *
   *  Total rewrite of read side for new NFS buffer cache.. Linus.
   *
   *  nfs regular file handling functions
   */

  #include <linux/module.h>

  #include <linux/time.h>
  #include <linux/kernel.h>
  #include <linux/errno.h>
  #include <linux/fcntl.h>
  #include <linux/stat.h>
  #include <linux/nfs_fs.h>
  #include <linux/nfs_mount.h>
  #include <linux/mm.h>

  #include <linux/pagemap.h>

  #include <linux/gfp.h>

  #include <linux/swap.h>

  
  #include <asm/uaccess.h>

  
  #include "delegation.h"

  #include "internal.h"

  #include "iostat.h"

  #include "fscache.h"

  #include "pnfs.h"

  #include "nfstrace.h"

  #define NFSDBG_FACILITY		NFSDBG_FILE

  static const struct vm_operations_struct nfs_file_vm_ops;

  /* Hack for future NFS swap support */
  #ifndef IS_SWAPFILE
  # define IS_SWAPFILE(inode)	(0)
  #endif

  int nfs_check_flags(int flags)

  {
  	if ((flags & (O_APPEND | O_DIRECT)) == (O_APPEND | O_DIRECT))
  		return -EINVAL;
  
  	return 0;
  }

  EXPORT_SYMBOL_GPL(nfs_check_flags);

  
  /*
   * Open file
   */
  static int
  nfs_file_open(struct inode *inode, struct file *filp)
  {

  	int res;

  	dprintk("NFS: open file(%pD2)
  ", filp);

  	nfs_inc_stats(inode, NFSIOS_VFSOPEN);

  	res = nfs_check_flags(filp->f_flags);
  	if (res)
  		return res;

  	res = nfs_open(inode, filp);

  	return res;
  }

  int

  nfs_file_release(struct inode *inode, struct file *filp)
  {

  	dprintk("NFS: release(%pD2)
  ", filp);

  	nfs_inc_stats(inode, NFSIOS_VFSRELEASE);

  	nfs_file_clear_open_context(filp);
  	return 0;

  }

  EXPORT_SYMBOL_GPL(nfs_file_release);

  /**
   * nfs_revalidate_size - Revalidate the file size
   * @inode - pointer to inode struct
   * @file - pointer to struct file
   *
   * Revalidates the file length. This is basically a wrapper around
   * nfs_revalidate_inode() that takes into account the fact that we may
   * have cached writes (in which case we don't care about the server's
   * idea of what the file length is), or O_DIRECT (in which case we
   * shouldn't trust the cache).
   */
  static int nfs_revalidate_file_size(struct inode *inode, struct file *filp)
  {
  	struct nfs_server *server = NFS_SERVER(inode);
  	struct nfs_inode *nfsi = NFS_I(inode);

  	if (nfs_have_delegated_attributes(inode))
  		goto out_noreval;

  	if (filp->f_flags & O_DIRECT)
  		goto force_reval;

  	if (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
  		goto force_reval;
  	if (nfs_attribute_timeout(inode))
  		goto force_reval;
  out_noreval:
  	return 0;

  force_reval:
  	return __nfs_revalidate_inode(server, inode);
  }

  loff_t nfs_file_llseek(struct file *filp, loff_t offset, int whence)

  {

  	dprintk("NFS: llseek file(%pD2, %lld, %d)
  ",
  			filp, offset, whence);

  	/*

  	 * whence == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate

  	 * the cached file length
  	 */

  	if (whence != SEEK_SET && whence != SEEK_CUR) {

  		struct inode *inode = filp->f_mapping->host;

  		int retval = nfs_revalidate_file_size(inode, filp);
  		if (retval < 0)
  			return (loff_t)retval;

  	}

  	return generic_file_llseek(filp, offset, whence);

  }

  EXPORT_SYMBOL_GPL(nfs_file_llseek);

  /*
   * Flush all dirty pages, and check for write errors.

   */

  static int

  nfs_file_flush(struct file *file, fl_owner_t id)

  {

  	struct inode	*inode = file_inode(file);

  	dprintk("NFS: flush(%pD2)
  ", file);

  	nfs_inc_stats(inode, NFSIOS_VFSFLUSH);

  	if ((file->f_mode & FMODE_WRITE) == 0)
  		return 0;

  	/* Flush writes to the server and return any errors */

  	return vfs_fsync(file, 0);

  }

  ssize_t

  nfs_file_read(struct kiocb *iocb, struct iov_iter *to)

  {

  	struct inode *inode = file_inode(iocb->ki_filp);

  	ssize_t result;

  	if (iocb->ki_flags & IOCB_DIRECT)

  		return nfs_file_direct_read(iocb, to);

  	dprintk("NFS: read(%pD2, %zu@%lu)
  ",

  		iocb->ki_filp,

  		iov_iter_count(to), (unsigned long) iocb->ki_pos);

  	nfs_start_io_read(inode);
  	result = nfs_revalidate_mapping(inode, iocb->ki_filp->f_mapping);

  	if (!result) {

  		result = generic_file_read_iter(iocb, to);

  		if (result > 0)
  			nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, result);
  	}

  	nfs_end_io_read(inode);

  	return result;
  }

  EXPORT_SYMBOL_GPL(nfs_file_read);

  int

  nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
  {

  	struct inode *inode = file_inode(file);

  	int	status;

  	dprintk("NFS: mmap(%pD2)
  ", file);

  	/* Note: generic_file_mmap() returns ENOSYS on nommu systems
  	 *       so we call that before revalidating the mapping
  	 */
  	status = generic_file_mmap(file, vma);

  	if (!status) {
  		vma->vm_ops = &nfs_file_vm_ops;

  		status = nfs_revalidate_mapping(inode, file->f_mapping);

  	}

  	return status;
  }

  EXPORT_SYMBOL_GPL(nfs_file_mmap);

  
  /*
   * Flush any dirty pages for this process, and check for write errors.
   * The return status from this call provides a reliable indication of
   * whether any write errors occurred for this process.

   *
   * Notice that it clears the NFS_CONTEXT_ERROR_WRITE before synching to
   * disk, but it retrieves and clears ctx->error after synching, despite
   * the two being set at the same time in nfs_context_set_write_error().
   * This is because the former is used to notify the _next_ call to

   * nfs_file_write() that a write error occurred, and hence cause it to

   * fall back to doing a synchronous write.

   */

  static int

  nfs_file_fsync_commit(struct file *file, loff_t start, loff_t end, int datasync)

  {

  	struct nfs_open_context *ctx = nfs_file_open_context(file);

  	struct inode *inode = file_inode(file);

  	int have_error, do_resend, status;

  	int ret = 0;

  	dprintk("NFS: fsync file(%pD2) datasync %d
  ", file, datasync);

  	nfs_inc_stats(inode, NFSIOS_VFSFSYNC);

  	do_resend = test_and_clear_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags);

  	have_error = test_and_clear_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
  	status = nfs_commit_inode(inode, FLUSH_SYNC);
  	have_error |= test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);

  	if (have_error) {

  		ret = xchg(&ctx->error, 0);

  		if (ret)
  			goto out;
  	}
  	if (status < 0) {

  		ret = status;

  		goto out;
  	}
  	do_resend |= test_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags);
  	if (do_resend)
  		ret = -EAGAIN;
  out:

  	return ret;
  }

  int

  nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
  {
  	int ret;

  	struct inode *inode = file_inode(file);

  	trace_nfs_fsync_enter(inode);

  	do {
  		ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
  		if (ret != 0)
  			break;

  		ret = nfs_file_fsync_commit(file, start, end, datasync);

  		if (!ret)
  			ret = pnfs_sync_inode(inode, !!datasync);

  		/*
  		 * If nfs_file_fsync_commit detected a server reboot, then
  		 * resend all dirty pages that might have been covered by
  		 * the NFS_CONTEXT_RESEND_WRITES flag
  		 */
  		start = 0;
  		end = LLONG_MAX;

  	} while (ret == -EAGAIN);

  	trace_nfs_fsync_exit(inode, ret);

  	return ret;

  }

  EXPORT_SYMBOL_GPL(nfs_file_fsync);

  
  /*

   * Decide whether a read/modify/write cycle may be more efficient
   * then a modify/write/read cycle when writing to a page in the
   * page cache.
   *
   * The modify/write/read cycle may occur if a page is read before
   * being completely filled by the writer.  In this situation, the
   * page must be completely written to stable storage on the server
   * before it can be refilled by reading in the page from the server.
   * This can lead to expensive, small, FILE_SYNC mode writes being
   * done.
   *
   * It may be more efficient to read the page first if the file is
   * open for reading in addition to writing, the page is not marked
   * as Uptodate, it is not dirty or waiting to be committed,
   * indicating that it was previously allocated and then modified,
   * that there were valid bytes of data in that range of the file,
   * and that the new data won't completely replace the old data in
   * that range of the file.
   */
  static int nfs_want_read_modify_write(struct file *file, struct page *page,
  			loff_t pos, unsigned len)
  {
  	unsigned int pglen = nfs_page_length(page);

  	unsigned int offset = pos & (PAGE_SIZE - 1);

  	unsigned int end = offset + len;

  	if (pnfs_ld_read_whole_page(file->f_mapping->host)) {
  		if (!PageUptodate(page))
  			return 1;
  		return 0;
  	}

  	if ((file->f_mode & FMODE_READ) &&	/* open for read? */
  	    !PageUptodate(page) &&		/* Uptodate? */
  	    !PagePrivate(page) &&		/* i/o request already? */
  	    pglen &&				/* valid bytes of file? */
  	    (end < pglen || offset))		/* replace all valid bytes? */
  		return 1;
  	return 0;
  }
  
  /*

   * This does the "real" work of the write. We must allocate and lock the
   * page to be sent back to the generic routine, which then copies the
   * data from user space.

   *
   * 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 nfs_write_begin(struct file *file, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned flags,
  			struct page **pagep, void **fsdata)

  {

  	int ret;

  	pgoff_t index = pos >> PAGE_SHIFT;

  	struct page *page;

  	int once_thru = 0;

  	dfprintk(PAGECACHE, "NFS: write_begin(%pD2(%lu), %u@%lld)
  ",

  		file, mapping->host->i_ino, len, (long long) pos);

  start:

  	page = grab_cache_page_write_begin(mapping, index, flags);

  	if (!page)
  		return -ENOMEM;
  	*pagep = page;
  
  	ret = nfs_flush_incompatible(file, page);
  	if (ret) {
  		unlock_page(page);

  		put_page(page);

  	} else if (!once_thru &&
  		   nfs_want_read_modify_write(file, page, pos, len)) {
  		once_thru = 1;
  		ret = nfs_readpage(file, page);

  		put_page(page);

  		if (!ret)
  			goto start;

  	}
  	return ret;

  }

  static int nfs_write_end(struct file *file, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned copied,
  			struct page *page, void *fsdata)

  {

  	unsigned offset = pos & (PAGE_SIZE - 1);

  	struct nfs_open_context *ctx = nfs_file_open_context(file);

  	int status;

  	dfprintk(PAGECACHE, "NFS: write_end(%pD2(%lu), %u@%lld)
  ",

  		file, mapping->host->i_ino, len, (long long) pos);

  	/*
  	 * Zero any uninitialised parts of the page, and then mark the page
  	 * as up to date if it turns out that we're extending the file.
  	 */
  	if (!PageUptodate(page)) {
  		unsigned pglen = nfs_page_length(page);

  		unsigned end = offset + copied;

  
  		if (pglen == 0) {
  			zero_user_segments(page, 0, offset,

  					end, PAGE_SIZE);

  			SetPageUptodate(page);
  		} else if (end >= pglen) {

  			zero_user_segment(page, end, PAGE_SIZE);

  			if (offset == 0)
  				SetPageUptodate(page);
  		} else

  			zero_user_segment(page, pglen, PAGE_SIZE);

  	}

  	status = nfs_updatepage(file, page, offset, copied);

  
  	unlock_page(page);

  	put_page(page);

  	if (status < 0)
  		return status;

  	NFS_I(mapping->host)->write_io += copied;

  	if (nfs_ctx_key_to_expire(ctx, mapping->host)) {

  		status = nfs_wb_all(mapping->host);
  		if (status < 0)
  			return status;
  	}

  	return copied;

  }

  /*
   * Partially or wholly invalidate a page
   * - Release the private state associated with a page if undergoing complete
   *   page invalidation

   * - Called if either PG_private or PG_fscache is set on the page

   * - Caller holds page lock
   */

  static void nfs_invalidate_page(struct page *page, unsigned int offset,
  				unsigned int length)

  {

  	dfprintk(PAGECACHE, "NFS: invalidate_page(%p, %u, %u)
  ",
  		 page, offset, length);

  	if (offset != 0 || length < PAGE_SIZE)

  		return;

  	/* Cancel any unstarted writes on this page */

  	nfs_wb_page_cancel(page_file_mapping(page)->host, page);

  
  	nfs_fscache_invalidate_page(page, page->mapping->host);

  }

  /*
   * Attempt to release the private state associated with a page

   * - Called if either PG_private or PG_fscache is set on the page

   * - Caller holds page lock
   * - Return true (may release page) or false (may not)
   */

  static int nfs_release_page(struct page *page, gfp_t gfp)
  {

  	dfprintk(PAGECACHE, "NFS: release_page(%p)
  ", page);

  	/* If PagePrivate() is set, then the page is not freeable */

  	if (PagePrivate(page))
  		return 0;
  	return nfs_fscache_release_page(page, gfp);

  }

  static void nfs_check_dirty_writeback(struct page *page,
  				bool *dirty, bool *writeback)
  {
  	struct nfs_inode *nfsi;
  	struct address_space *mapping = page_file_mapping(page);
  
  	if (!mapping || PageSwapCache(page))
  		return;
  
  	/*
  	 * Check if an unstable page is currently being committed and
  	 * if so, have the VM treat it as if the page is under writeback
  	 * so it will not block due to pages that will shortly be freeable.
  	 */
  	nfsi = NFS_I(mapping->host);

  	if (atomic_read(&nfsi->commit_info.rpcs_out)) {

  		*writeback = true;
  		return;
  	}
  
  	/*
  	 * If PagePrivate() is set, then the page is not freeable and as the
  	 * inode is not being committed, it's not going to be cleaned in the
  	 * near future so treat it as dirty
  	 */
  	if (PagePrivate(page))
  		*dirty = true;
  }

  /*
   * Attempt to clear the private state associated with a page when an error
   * occurs that requires the cached contents of an inode to be written back or
   * destroyed

   * - Called if either PG_private or fscache is set on the page

   * - Caller holds page lock
   * - Return 0 if successful, -error otherwise
   */

  static int nfs_launder_page(struct page *page)
  {

  	struct inode *inode = page_file_mapping(page)->host;

  	struct nfs_inode *nfsi = NFS_I(inode);

  
  	dfprintk(PAGECACHE, "NFS: launder_page(%ld, %llu)
  ",
  		inode->i_ino, (long long)page_offset(page));

  	nfs_fscache_wait_on_page_write(nfsi, page);

  	return nfs_wb_launder_page(inode, page);

  }

  static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
  						sector_t *span)
  {

  	struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);

  	*span = sis->pages;

  	return rpc_clnt_swap_activate(clnt);

  }
  
  static void nfs_swap_deactivate(struct file *file)
  {

  	struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);

  	rpc_clnt_swap_deactivate(clnt);

  }

  const struct address_space_operations nfs_file_aops = {

  	.readpage = nfs_readpage,
  	.readpages = nfs_readpages,

  	.set_page_dirty = __set_page_dirty_nobuffers,

  	.writepage = nfs_writepage,
  	.writepages = nfs_writepages,

  	.write_begin = nfs_write_begin,
  	.write_end = nfs_write_end,

  	.invalidatepage = nfs_invalidate_page,
  	.releasepage = nfs_release_page,

  	.direct_IO = nfs_direct_IO,

  #ifdef CONFIG_MIGRATION

  	.migratepage = nfs_migrate_page,

  #endif

  	.launder_page = nfs_launder_page,

  	.is_dirty_writeback = nfs_check_dirty_writeback,

  	.error_remove_page = generic_error_remove_page,

  	.swap_activate = nfs_swap_activate,
  	.swap_deactivate = nfs_swap_deactivate,

  };

  /*
   * Notification that a PTE pointing to an NFS page is about to be made
   * writable, implying that someone is about to modify the page through a
   * shared-writable mapping
   */

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

  {

  	struct page *page = vmf->page;

  	struct file *filp = vma->vm_file;

  	struct inode *inode = file_inode(filp);

  	unsigned pagelen;

  	int ret = VM_FAULT_NOPAGE;

  	struct address_space *mapping;

  	dfprintk(PAGECACHE, "NFS: vm_page_mkwrite(%pD2(%lu), offset %lld)
  ",

  		filp, filp->f_mapping->host->i_ino,

  		(long long)page_offset(page));

  	sb_start_pagefault(inode->i_sb);

  	/* make sure the cache has finished storing the page */

  	nfs_fscache_wait_on_page_write(NFS_I(inode), page);

  	wait_on_bit_action(&NFS_I(inode)->flags, NFS_INO_INVALIDATING,
  			nfs_wait_bit_killable, TASK_KILLABLE);

  	lock_page(page);

  	mapping = page_file_mapping(page);

  	if (mapping != inode->i_mapping)

  		goto out_unlock;

  	wait_on_page_writeback(page);

  	pagelen = nfs_page_length(page);

  	if (pagelen == 0)
  		goto out_unlock;

  	ret = VM_FAULT_LOCKED;
  	if (nfs_flush_incompatible(filp, page) == 0 &&
  	    nfs_updatepage(filp, page, 0, pagelen) == 0)
  		goto out;

  	ret = VM_FAULT_SIGBUS;

  out_unlock:
  	unlock_page(page);

  out:

  	sb_end_pagefault(inode->i_sb);

  	return ret;

  }

  static const struct vm_operations_struct nfs_file_vm_ops = {

  	.fault = filemap_fault,

  	.map_pages = filemap_map_pages,

  	.page_mkwrite = nfs_vm_page_mkwrite,
  };

  static int nfs_need_check_write(struct file *filp, struct inode *inode)

  {
  	struct nfs_open_context *ctx;

  	ctx = nfs_file_open_context(filp);

  	if (test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags) ||

  	    nfs_ctx_key_to_expire(ctx, inode))

  		return 1;
  	return 0;
  }

  ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from)

  {

  	struct file *file = iocb->ki_filp;
  	struct inode *inode = file_inode(file);

  	unsigned long written = 0;

  	ssize_t result;

  	result = nfs_key_timeout_notify(file, inode);

  	if (result)
  		return result;

  	if (iocb->ki_flags & IOCB_DIRECT)

  		return nfs_file_direct_write(iocb, from);

  	dprintk("NFS: write(%pD2, %zu@%Ld)
  ",

  		file, iov_iter_count(from), (long long) iocb->ki_pos);

  	if (IS_SWAPFILE(inode))
  		goto out_swapfile;

  	/*
  	 * O_APPEND implies that we must revalidate the file length.
  	 */

  	if (iocb->ki_flags & IOCB_APPEND) {

  		result = nfs_revalidate_file_size(inode, file);

  		if (result)
  			goto out;

  	}

  	nfs_start_io_write(inode);

  	result = generic_write_checks(iocb, from);
  	if (result > 0) {
  		current->backing_dev_info = inode_to_bdi(inode);
  		result = generic_perform_write(file, from, iocb->ki_pos);
  		current->backing_dev_info = NULL;
  	}

  	nfs_end_io_write(inode);

  	if (result <= 0)

  		goto out;

  	result = generic_write_sync(iocb, result);
  	if (result < 0)
  		goto out;
  	written = result;

  	iocb->ki_pos += written;

  	/* Return error values */

  	if (nfs_need_check_write(file, inode)) {

  		int err = vfs_fsync(file, 0);

  		if (err < 0)
  			result = err;
  	}

  	nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written);

  out:
  	return result;
  
  out_swapfile:
  	printk(KERN_INFO "NFS: attempt to write to active swap file!
  ");

  	return -EBUSY;

  }

  EXPORT_SYMBOL_GPL(nfs_file_write);

  static int
  do_getlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)

  {
  	struct inode *inode = filp->f_mapping->host;
  	int status = 0;

  	unsigned int saved_type = fl->fl_type;

  	/* Try local locking first */

  	posix_test_lock(filp, fl);
  	if (fl->fl_type != F_UNLCK) {
  		/* found a conflict */

  		goto out;

  	}

  	fl->fl_type = saved_type;

  	if (NFS_PROTO(inode)->have_delegation(inode, FMODE_READ))

  		goto out_noconflict;

  	if (is_local)

  		goto out_noconflict;
  
  	status = NFS_PROTO(inode)->lock(filp, cmd, fl);
  out:

  	return status;

  out_noconflict:
  	fl->fl_type = F_UNLCK;
  	goto out;

  }

  static int
  do_unlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)

  {
  	struct inode *inode = filp->f_mapping->host;

  	struct nfs_lock_context *l_ctx;

  	int status;

  	/*
  	 * Flush all pending writes before doing anything
  	 * with locks..
  	 */

  	vfs_fsync(filp, 0);

  	l_ctx = nfs_get_lock_context(nfs_file_open_context(filp));
  	if (!IS_ERR(l_ctx)) {

  		status = nfs_iocounter_wait(l_ctx);

  		nfs_put_lock_context(l_ctx);
  		if (status < 0)
  			return status;
  	}

  	/* NOTE: special case
  	 * 	If we're signalled while cleaning up locks on process exit, we
  	 * 	still need to complete the unlock.
  	 */

  	/*
  	 * Use local locking if mounted with "-onolock" or with appropriate
  	 * "-olocal_lock="
  	 */
  	if (!is_local)

  		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
  	else

  		status = locks_lock_file_wait(filp, fl);

  	return status;
  }

  static int
  do_setlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)

  {
  	struct inode *inode = filp->f_mapping->host;

  	int status;

  	/*
  	 * Flush all pending writes before doing anything
  	 * with locks..
  	 */

  	status = nfs_sync_mapping(filp->f_mapping);
  	if (status != 0)

  		goto out;

  	/*
  	 * Use local locking if mounted with "-onolock" or with appropriate
  	 * "-olocal_lock="
  	 */
  	if (!is_local)

  		status = NFS_PROTO(inode)->lock(filp, cmd, fl);

  	else

  		status = locks_lock_file_wait(filp, fl);

  	if (status < 0)
  		goto out;

  	/*

  	 * Revalidate the cache if the server has time stamps granular
  	 * enough to detect subsecond changes.  Otherwise, clear the
  	 * cache to prevent missing any changes.
  	 *

  	 * This makes locking act as a cache coherency point.
  	 */

  	nfs_sync_mapping(filp->f_mapping);

  	if (!NFS_PROTO(inode)->have_delegation(inode, FMODE_READ))
  		nfs_zap_mapping(inode, filp->f_mapping);

  out:

  	return status;
  }
  
  /*
   * Lock a (portion of) a file
   */

  int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)

  {

  	struct inode *inode = filp->f_mapping->host;

  	int ret = -ENOLCK;

  	int is_local = 0;

  	dprintk("NFS: lock(%pD2, t=%x, fl=%x, r=%lld:%lld)
  ",
  			filp, fl->fl_type, fl->fl_flags,

  			(long long)fl->fl_start, (long long)fl->fl_end);

  	nfs_inc_stats(inode, NFSIOS_VFSLOCK);

  
  	/* No mandatory locks over NFS */

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

  		goto out_err;

  	if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FCNTL)
  		is_local = 1;

  	if (NFS_PROTO(inode)->lock_check_bounds != NULL) {
  		ret = NFS_PROTO(inode)->lock_check_bounds(fl);
  		if (ret < 0)
  			goto out_err;
  	}

  
  	if (IS_GETLK(cmd))

  		ret = do_getlk(filp, cmd, fl, is_local);

  	else if (fl->fl_type == F_UNLCK)

  		ret = do_unlk(filp, cmd, fl, is_local);

  	else

  		ret = do_setlk(filp, cmd, fl, is_local);

  out_err:
  	return ret;

  }

  EXPORT_SYMBOL_GPL(nfs_lock);

  
  /*
   * Lock a (portion of) a file
   */

  int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)

  {

  	struct inode *inode = filp->f_mapping->host;
  	int is_local = 0;

  	dprintk("NFS: flock(%pD2, t=%x, fl=%x)
  ",
  			filp, fl->fl_type, fl->fl_flags);

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

  	/*
  	 * The NFSv4 protocol doesn't support LOCK_MAND, which is not part of
  	 * any standard. In principle we might be able to support LOCK_MAND
  	 * on NFSv2/3 since NLMv3/4 support DOS share modes, but for now the
  	 * NFS code is not set up for it.
  	 */
  	if (fl->fl_type & LOCK_MAND)
  		return -EINVAL;

  	if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK)
  		is_local = 1;

  	/* We're simulating flock() locks using posix locks on the server */

  	if (fl->fl_type == F_UNLCK)

  		return do_unlk(filp, cmd, fl, is_local);
  	return do_setlk(filp, cmd, fl, is_local);

  }

  EXPORT_SYMBOL_GPL(nfs_flock);

  const struct file_operations nfs_file_operations = {
  	.llseek		= nfs_file_llseek,

  	.read_iter	= nfs_file_read,

  	.write_iter	= nfs_file_write,

  	.mmap		= nfs_file_mmap,
  	.open		= nfs_file_open,
  	.flush		= nfs_file_flush,
  	.release	= nfs_file_release,
  	.fsync		= nfs_file_fsync,
  	.lock		= nfs_lock,
  	.flock		= nfs_flock,

  	.splice_read	= generic_file_splice_read,

  	.splice_write	= iter_file_splice_write,

  	.check_flags	= nfs_check_flags,

  	.setlease	= simple_nosetlease,

  };

  EXPORT_SYMBOL_GPL(nfs_file_operations);