/*
   *  linux/fs/nfs/file.c
   *
   *  Copyright (C) 1992  Rick Sladkey
   */

  #include <linux/fs.h>

  #include <linux/file.h>

  #include <linux/falloc.h>

  #include <linux/nfs_fs.h>

  #include <uapi/linux/btrfs.h>	/* BTRFS_IOC_CLONE/BTRFS_IOC_CLONE_RANGE */

  #include "delegation.h"

  #include "internal.h"

  #include "iostat.h"

  #include "fscache.h"

  #include "pnfs.h"

  #include "nfstrace.h"

  #ifdef CONFIG_NFS_V4_2
  #include "nfs42.h"
  #endif

  #define NFSDBG_FACILITY		NFSDBG_FILE
  
  static int
  nfs4_file_open(struct inode *inode, struct file *filp)
  {
  	struct nfs_open_context *ctx;

  	struct dentry *dentry = file_dentry(filp);

  	struct dentry *parent = NULL;
  	struct inode *dir;
  	unsigned openflags = filp->f_flags;
  	struct iattr attr;
  	int err;

  	/*
  	 * If no cached dentry exists or if it's negative, NFSv4 handled the
  	 * opens in ->lookup() or ->create().
  	 *
  	 * We only get this far for a cached positive dentry.  We skipped
  	 * revalidation, so handle it here by dropping the dentry and returning
  	 * -EOPENSTALE.  The VFS will retry the lookup/create/open.
  	 */

  	dprintk("NFS: open file(%pd2)
  ", dentry);

  	err = nfs_check_flags(openflags);
  	if (err)
  		return err;

  	if ((openflags & O_ACCMODE) == 3)
  		openflags--;
  
  	/* We can't create new files here */
  	openflags &= ~(O_CREAT|O_EXCL);
  
  	parent = dget_parent(dentry);

  	dir = d_inode(parent);

  	ctx = alloc_nfs_open_context(file_dentry(filp), filp->f_mode);

  	err = PTR_ERR(ctx);
  	if (IS_ERR(ctx))
  		goto out;
  
  	attr.ia_valid = ATTR_OPEN;
  	if (openflags & O_TRUNC) {
  		attr.ia_valid |= ATTR_SIZE;
  		attr.ia_size = 0;

  		nfs_sync_inode(inode);

  	}

  	inode = NFS_PROTO(dir)->open_context(dir, ctx, openflags, &attr, NULL);

  	if (IS_ERR(inode)) {
  		err = PTR_ERR(inode);
  		switch (err) {
  		case -EPERM:
  		case -EACCES:
  		case -EDQUOT:
  		case -ENOSPC:
  		case -EROFS:
  			goto out_put_ctx;
  		default:
  			goto out_drop;
  		}
  	}

  	if (inode != d_inode(dentry))

  		goto out_drop;
  
  	nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
  	nfs_file_set_open_context(filp, ctx);

  	nfs_fscache_open_file(inode, filp);

  	err = 0;
  
  out_put_ctx:
  	put_nfs_open_context(ctx);
  out:
  	dput(parent);
  	return err;
  
  out_drop:
  	d_drop(dentry);
  	err = -EOPENSTALE;
  	goto out_put_ctx;
  }

  /*
   * Flush all dirty pages, and check for write errors.
   */
  static int
  nfs4_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;
  
  	/*
  	 * If we're holding a write delegation, then check if we're required
  	 * to flush the i/o on close. If not, then just start the i/o now.
  	 */
  	if (!nfs4_delegation_flush_on_close(inode))
  		return filemap_fdatawrite(file->f_mapping);
  
  	/* Flush writes to the server and return any errors */
  	return vfs_fsync(file, 0);
  }

  #ifdef CONFIG_NFS_V4_2
  static loff_t nfs4_file_llseek(struct file *filep, loff_t offset, int whence)
  {
  	loff_t ret;
  
  	switch (whence) {
  	case SEEK_HOLE:
  	case SEEK_DATA:
  		ret = nfs42_proc_llseek(filep, offset, whence);
  		if (ret != -ENOTSUPP)
  			return ret;
  	default:
  		return nfs_file_llseek(filep, offset, whence);
  	}
  }

  
  static long nfs42_fallocate(struct file *filep, int mode, loff_t offset, loff_t len)
  {
  	struct inode *inode = file_inode(filep);
  	long ret;
  
  	if (!S_ISREG(inode->i_mode))
  		return -EOPNOTSUPP;

  	if ((mode != 0) && (mode != (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE)))

  		return -EOPNOTSUPP;
  
  	ret = inode_newsize_ok(inode, offset + len);
  	if (ret < 0)
  		return ret;

  	if (mode & FALLOC_FL_PUNCH_HOLE)

  		return nfs42_proc_deallocate(filep, offset, len);
  	return nfs42_proc_allocate(filep, offset, len);

  }

  static int nfs42_clone_file_range(struct file *src_file, loff_t src_off,
  		struct file *dst_file, loff_t dst_off, u64 count)

  {
  	struct inode *dst_inode = file_inode(dst_file);

  	struct nfs_server *server = NFS_SERVER(dst_inode);

  	struct inode *src_inode = file_inode(src_file);

  	unsigned int bs = server->clone_blksize;

  	bool same_inode = false;

  	int ret;

  	/* check alignment w.r.t. clone_blksize */
  	ret = -EINVAL;
  	if (bs) {
  		if (!IS_ALIGNED(src_off, bs) || !IS_ALIGNED(dst_off, bs))

  			goto out;

  		if (!IS_ALIGNED(count, bs) && i_size_read(src_inode) != (src_off + count))

  			goto out;

  	}

  	if (src_inode == dst_inode)
  		same_inode = true;

  	/* XXX: do we lock at all? what if server needs CB_RECALL_LAYOUT? */

  	if (same_inode) {

  		inode_lock(src_inode);

  	} else if (dst_inode < src_inode) {

  		inode_lock_nested(dst_inode, I_MUTEX_PARENT);
  		inode_lock_nested(src_inode, I_MUTEX_CHILD);

  	} else {

  		inode_lock_nested(src_inode, I_MUTEX_PARENT);
  		inode_lock_nested(dst_inode, I_MUTEX_CHILD);

  	}
  
  	/* flush all pending writes on both src and dst so that server
  	 * has the latest data */
  	ret = nfs_sync_inode(src_inode);
  	if (ret)
  		goto out_unlock;
  	ret = nfs_sync_inode(dst_inode);
  	if (ret)
  		goto out_unlock;

  	ret = nfs42_proc_clone(src_file, dst_file, src_off, dst_off, count);

  
  	/* truncate inode page cache of the dst range so that future reads can fetch
  	 * new data from server */
  	if (!ret)
  		truncate_inode_pages_range(&dst_inode->i_data, dst_off, dst_off + count - 1);
  
  out_unlock:

  	if (same_inode) {

  		inode_unlock(src_inode);

  	} else if (dst_inode < src_inode) {

  		inode_unlock(src_inode);
  		inode_unlock(dst_inode);

  	} else {

  		inode_unlock(dst_inode);
  		inode_unlock(src_inode);

  	}

  out:

  	return ret;
  }

  #endif /* CONFIG_NFS_V4_2 */

  const struct file_operations nfs4_file_operations = {

  	.read_iter	= nfs_file_read,

  	.write_iter	= nfs_file_write,

  	.mmap		= nfs_file_mmap,
  	.open		= nfs4_file_open,

  	.flush		= nfs4_file_flush,

  	.release	= nfs_file_release,

  	.fsync		= nfs_file_fsync,

  	.lock		= nfs_lock,
  	.flock		= nfs_flock,
  	.splice_read	= nfs_file_splice_read,

  	.splice_write	= iter_file_splice_write,

  	.check_flags	= nfs_check_flags,

  	.setlease	= simple_nosetlease,

  #ifdef CONFIG_NFS_V4_2
  	.llseek		= nfs4_file_llseek,
  	.fallocate	= nfs42_fallocate,

  	.clone_file_range = nfs42_clone_file_range,

  #else
  	.llseek		= nfs_file_llseek,
  #endif

  };