#include <linux/ceph/ceph_debug.h>

  #include <linux/module.h>

  #include <linux/sched.h>

  #include <linux/slab.h>

  #include <linux/file.h>

  #include <linux/mount.h>

  #include <linux/namei.h>
  #include <linux/writeback.h>

  #include <linux/falloc.h>

  
  #include "super.h"
  #include "mds_client.h"

  #include "cache.h"

  
  /*
   * Ceph file operations
   *
   * Implement basic open/close functionality, and implement
   * read/write.
   *
   * We implement three modes of file I/O:
   *  - buffered uses the generic_file_aio_{read,write} helpers
   *
   *  - synchronous is used when there is multi-client read/write
   *    sharing, avoids the page cache, and synchronously waits for an
   *    ack from the OSD.
   *
   *  - direct io takes the variant of the sync path that references
   *    user pages directly.
   *
   * fsync() flushes and waits on dirty pages, but just queues metadata
   * for writeback: since the MDS can recover size and mtime there is no
   * need to wait for MDS acknowledgement.
   */

  /*
   * Calculate the length sum of direct io vectors that can
   * be combined into one page vector.
   */
  static size_t dio_get_pagev_size(const struct iov_iter *it)
  {
      const struct iovec *iov = it->iov;
      const struct iovec *iovend = iov + it->nr_segs;
      size_t size;
  
      size = iov->iov_len - it->iov_offset;
      /*
       * An iov can be page vectored when both the current tail
       * and the next base are page aligned.
       */
      while (PAGE_ALIGNED((iov->iov_base + iov->iov_len)) &&
             (++iov < iovend && PAGE_ALIGNED((iov->iov_base)))) {
          size += iov->iov_len;
      }
      dout("dio_get_pagevlen len = %zu
  ", size);
      return size;
  }
  
  /*
   * Allocate a page vector based on (@it, @nbytes).
   * The return value is the tuple describing a page vector,
   * that is (@pages, @page_align, @num_pages).
   */
  static struct page **
  dio_get_pages_alloc(const struct iov_iter *it, size_t nbytes,
  		    size_t *page_align, int *num_pages)
  {
  	struct iov_iter tmp_it = *it;
  	size_t align;
  	struct page **pages;
  	int ret = 0, idx, npages;
  
  	align = (unsigned long)(it->iov->iov_base + it->iov_offset) &
  		(PAGE_SIZE - 1);
  	npages = calc_pages_for(align, nbytes);
  	pages = kmalloc(sizeof(*pages) * npages, GFP_KERNEL);
  	if (!pages) {
  		pages = vmalloc(sizeof(*pages) * npages);
  		if (!pages)
  			return ERR_PTR(-ENOMEM);
  	}
  
  	for (idx = 0; idx < npages; ) {
  		size_t start;
  		ret = iov_iter_get_pages(&tmp_it, pages + idx, nbytes,
  					 npages - idx, &start);
  		if (ret < 0)
  			goto fail;
  
  		iov_iter_advance(&tmp_it, ret);
  		nbytes -= ret;
  		idx += (ret + start + PAGE_SIZE - 1) / PAGE_SIZE;
  	}
  
  	BUG_ON(nbytes != 0);
  	*num_pages = npages;
  	*page_align = align;
  	dout("dio_get_pages_alloc: got %d pages align %zu
  ", npages, align);
  	return pages;
  fail:
  	ceph_put_page_vector(pages, idx, false);
  	return ERR_PTR(ret);
  }

  
  /*
   * Prepare an open request.  Preallocate ceph_cap to avoid an
   * inopportune ENOMEM later.
   */
  static struct ceph_mds_request *
  prepare_open_request(struct super_block *sb, int flags, int create_mode)
  {

  	struct ceph_fs_client *fsc = ceph_sb_to_client(sb);
  	struct ceph_mds_client *mdsc = fsc->mdsc;

  	struct ceph_mds_request *req;
  	int want_auth = USE_ANY_MDS;
  	int op = (flags & O_CREAT) ? CEPH_MDS_OP_CREATE : CEPH_MDS_OP_OPEN;
  
  	if (flags & (O_WRONLY|O_RDWR|O_CREAT|O_TRUNC))
  		want_auth = USE_AUTH_MDS;
  
  	req = ceph_mdsc_create_request(mdsc, op, want_auth);
  	if (IS_ERR(req))
  		goto out;
  	req->r_fmode = ceph_flags_to_mode(flags);
  	req->r_args.open.flags = cpu_to_le32(flags);
  	req->r_args.open.mode = cpu_to_le32(create_mode);

  out:
  	return req;
  }
  
  /*
   * initialize private struct file data.
   * if we fail, clean up by dropping fmode reference on the ceph_inode
   */
  static int ceph_init_file(struct inode *inode, struct file *file, int fmode)
  {
  	struct ceph_file_info *cf;
  	int ret = 0;
  
  	switch (inode->i_mode & S_IFMT) {
  	case S_IFREG:

  		ceph_fscache_register_inode_cookie(inode);
  		ceph_fscache_file_set_cookie(inode, file);

  	case S_IFDIR:
  		dout("init_file %p %p 0%o (regular)
  ", inode, file,
  		     inode->i_mode);

  		cf = kmem_cache_zalloc(ceph_file_cachep, GFP_KERNEL);

  		if (cf == NULL) {
  			ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
  			return -ENOMEM;
  		}
  		cf->fmode = fmode;
  		cf->next_offset = 2;

  		cf->readdir_cache_idx = -1;

  		file->private_data = cf;
  		BUG_ON(inode->i_fop->release != ceph_release);
  		break;
  
  	case S_IFLNK:
  		dout("init_file %p %p 0%o (symlink)
  ", inode, file,
  		     inode->i_mode);
  		ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
  		break;
  
  	default:
  		dout("init_file %p %p 0%o (special)
  ", inode, file,
  		     inode->i_mode);
  		/*
  		 * we need to drop the open ref now, since we don't
  		 * have .release set to ceph_release.
  		 */
  		ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
  		BUG_ON(inode->i_fop->release == ceph_release);
  
  		/* call the proper open fop */
  		ret = inode->i_fop->open(inode, file);
  	}
  	return ret;
  }
  
  /*

   * try renew caps after session gets killed.
   */
  int ceph_renew_caps(struct inode *inode)
  {
  	struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
  	struct ceph_inode_info *ci = ceph_inode(inode);
  	struct ceph_mds_request *req;
  	int err, flags, wanted;
  
  	spin_lock(&ci->i_ceph_lock);
  	wanted = __ceph_caps_file_wanted(ci);
  	if (__ceph_is_any_real_caps(ci) &&
  	    (!(wanted & CEPH_CAP_ANY_WR) == 0 || ci->i_auth_cap)) {
  		int issued = __ceph_caps_issued(ci, NULL);
  		spin_unlock(&ci->i_ceph_lock);
  		dout("renew caps %p want %s issued %s updating mds_wanted
  ",
  		     inode, ceph_cap_string(wanted), ceph_cap_string(issued));
  		ceph_check_caps(ci, 0, NULL);
  		return 0;
  	}
  	spin_unlock(&ci->i_ceph_lock);
  
  	flags = 0;
  	if ((wanted & CEPH_CAP_FILE_RD) && (wanted & CEPH_CAP_FILE_WR))
  		flags = O_RDWR;
  	else if (wanted & CEPH_CAP_FILE_RD)
  		flags = O_RDONLY;
  	else if (wanted & CEPH_CAP_FILE_WR)
  		flags = O_WRONLY;
  #ifdef O_LAZY
  	if (wanted & CEPH_CAP_FILE_LAZYIO)
  		flags |= O_LAZY;
  #endif
  
  	req = prepare_open_request(inode->i_sb, flags, 0);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto out;
  	}
  
  	req->r_inode = inode;
  	ihold(inode);
  	req->r_num_caps = 1;
  	req->r_fmode = -1;
  
  	err = ceph_mdsc_do_request(mdsc, NULL, req);
  	ceph_mdsc_put_request(req);
  out:
  	dout("renew caps %p open result=%d
  ", inode, err);
  	return err < 0 ? err : 0;
  }
  
  /*

   * If we already have the requisite capabilities, we can satisfy
   * the open request locally (no need to request new caps from the
   * MDS).  We do, however, need to inform the MDS (asynchronously)
   * if our wanted caps set expands.
   */
  int ceph_open(struct inode *inode, struct file *file)
  {
  	struct ceph_inode_info *ci = ceph_inode(inode);

  	struct ceph_fs_client *fsc = ceph_sb_to_client(inode->i_sb);
  	struct ceph_mds_client *mdsc = fsc->mdsc;

  	struct ceph_mds_request *req;
  	struct ceph_file_info *cf = file->private_data;

  	int err;
  	int flags, fmode, wanted;
  
  	if (cf) {
  		dout("open file %p is already opened
  ", file);
  		return 0;
  	}
  
  	/* filter out O_CREAT|O_EXCL; vfs did that already.  yuck. */
  	flags = file->f_flags & ~(O_CREAT|O_EXCL);
  	if (S_ISDIR(inode->i_mode))
  		flags = O_DIRECTORY;  /* mds likes to know */
  
  	dout("open inode %p ino %llx.%llx file %p flags %d (%d)
  ", inode,
  	     ceph_vinop(inode), file, flags, file->f_flags);
  	fmode = ceph_flags_to_mode(flags);
  	wanted = ceph_caps_for_mode(fmode);
  
  	/* snapped files are read-only */
  	if (ceph_snap(inode) != CEPH_NOSNAP && (file->f_mode & FMODE_WRITE))
  		return -EROFS;
  
  	/* trivially open snapdir */
  	if (ceph_snap(inode) == CEPH_SNAPDIR) {

  		spin_lock(&ci->i_ceph_lock);

  		__ceph_get_fmode(ci, fmode);

  		spin_unlock(&ci->i_ceph_lock);

  		return ceph_init_file(inode, file, fmode);
  	}
  
  	/*

  	 * No need to block if we have caps on the auth MDS (for
  	 * write) or any MDS (for read).  Update wanted set

  	 * asynchronously.
  	 */

  	spin_lock(&ci->i_ceph_lock);

  	if (__ceph_is_any_real_caps(ci) &&
  	    (((fmode & CEPH_FILE_MODE_WR) == 0) || ci->i_auth_cap)) {

  		int mds_wanted = __ceph_caps_mds_wanted(ci);
  		int issued = __ceph_caps_issued(ci, NULL);
  
  		dout("open %p fmode %d want %s issued %s using existing
  ",
  		     inode, fmode, ceph_cap_string(wanted),
  		     ceph_cap_string(issued));
  		__ceph_get_fmode(ci, fmode);

  		spin_unlock(&ci->i_ceph_lock);

  
  		/* adjust wanted? */
  		if ((issued & wanted) != wanted &&
  		    (mds_wanted & wanted) != wanted &&
  		    ceph_snap(inode) != CEPH_SNAPDIR)
  			ceph_check_caps(ci, 0, NULL);
  
  		return ceph_init_file(inode, file, fmode);
  	} else if (ceph_snap(inode) != CEPH_NOSNAP &&
  		   (ci->i_snap_caps & wanted) == wanted) {
  		__ceph_get_fmode(ci, fmode);

  		spin_unlock(&ci->i_ceph_lock);

  		return ceph_init_file(inode, file, fmode);
  	}

  	spin_unlock(&ci->i_ceph_lock);

  
  	dout("open fmode %d wants %s
  ", fmode, ceph_cap_string(wanted));
  	req = prepare_open_request(inode->i_sb, flags, 0);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto out;
  	}

  	req->r_inode = inode;
  	ihold(inode);

  	req->r_num_caps = 1;

  	err = ceph_mdsc_do_request(mdsc, NULL, req);

  	if (!err)
  		err = ceph_init_file(inode, file, req->r_fmode);
  	ceph_mdsc_put_request(req);
  	dout("open result=%d on %llx.%llx
  ", err, ceph_vinop(inode));
  out:
  	return err;
  }
  
  
  /*

   * Do a lookup + open with a single request.  If we get a non-existent
   * file or symlink, return 1 so the VFS can retry.

   */

  int ceph_atomic_open(struct inode *dir, struct dentry *dentry,

  		     struct file *file, unsigned flags, umode_t mode,

  		     int *opened)

  {

  	struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb);
  	struct ceph_mds_client *mdsc = fsc->mdsc;

  	struct ceph_mds_request *req;

  	struct dentry *dn;

  	struct ceph_acls_info acls = {};

         int mask;

  	int err;

  	dout("atomic_open %p dentry %p '%pd' %s flags %d mode 0%o
  ",
  	     dir, dentry, dentry,

  	     d_unhashed(dentry) ? "unhashed" : "hashed", flags, mode);
  
  	if (dentry->d_name.len > NAME_MAX)
  		return -ENAMETOOLONG;
  
  	err = ceph_init_dentry(dentry);
  	if (err < 0)
  		return err;

  	if (flags & O_CREAT) {
  		err = ceph_pre_init_acls(dir, &mode, &acls);
  		if (err < 0)
  			return err;
  	}

  	/* do the open */
  	req = prepare_open_request(dir->i_sb, flags, mode);

  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto out_acl;
  	}

  	req->r_dentry = dget(dentry);
  	req->r_num_caps = 2;
  	if (flags & O_CREAT) {
  		req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
  		req->r_dentry_unless = CEPH_CAP_FILE_EXCL;

  		if (acls.pagelist) {
  			req->r_pagelist = acls.pagelist;
  			acls.pagelist = NULL;
  		}

  	}

  
         mask = CEPH_STAT_CAP_INODE | CEPH_CAP_AUTH_SHARED;
         if (ceph_security_xattr_wanted(dir))
                 mask |= CEPH_CAP_XATTR_SHARED;
         req->r_args.open.mask = cpu_to_le32(mask);

  	req->r_locked_dir = dir;           /* caller holds dir->i_mutex */

  	err = ceph_mdsc_do_request(mdsc,
  				   (flags & (O_CREAT|O_TRUNC)) ? dir : NULL,
  				   req);

  	err = ceph_handle_snapdir(req, dentry, err);

  	if (err)

  		goto out_req;

  	if ((flags & O_CREAT) && !req->r_reply_info.head->is_dentry)

  		err = ceph_handle_notrace_create(dir, dentry);

  	if (d_in_lookup(dentry)) {

  		dn = ceph_finish_lookup(req, dentry, err);
  		if (IS_ERR(dn))
  			err = PTR_ERR(dn);
  	} else {
  		/* we were given a hashed negative dentry */
  		dn = NULL;
  	}
  	if (err)

  		goto out_req;

  	if (dn || d_really_is_negative(dentry) || d_is_symlink(dentry)) {

  		/* make vfs retry on splice, ENOENT, or symlink */
  		dout("atomic_open finish_no_open on dn %p
  ", dn);
  		err = finish_no_open(file, dn);
  	} else {
  		dout("atomic_open finish_open on dn %p
  ", dn);

  		if (req->r_op == CEPH_MDS_OP_CREATE && req->r_reply_info.has_create_ino) {

  			ceph_init_inode_acls(d_inode(dentry), &acls);

  			*opened |= FILE_CREATED;
  		}

  		err = finish_open(file, dentry, ceph_open, opened);
  	}

  out_req:

  	if (!req->r_err && req->r_target_inode)
  		ceph_put_fmode(ceph_inode(req->r_target_inode), req->r_fmode);

  	ceph_mdsc_put_request(req);

  out_acl:
  	ceph_release_acls_info(&acls);

  	dout("atomic_open result=%d
  ", err);

  	return err;

  }
  
  int ceph_release(struct inode *inode, struct file *file)
  {
  	struct ceph_inode_info *ci = ceph_inode(inode);
  	struct ceph_file_info *cf = file->private_data;
  
  	dout("release inode %p file %p
  ", inode, file);
  	ceph_put_fmode(ci, cf->fmode);
  	if (cf->last_readdir)
  		ceph_mdsc_put_request(cf->last_readdir);
  	kfree(cf->last_name);
  	kfree(cf->dir_info);

  	kmem_cache_free(ceph_file_cachep, cf);

  
  	/* wake up anyone waiting for caps on this inode */

  	wake_up_all(&ci->i_cap_wq);

  	return 0;
  }

  enum {

  	HAVE_RETRIED = 1,
  	CHECK_EOF =    2,
  	READ_INLINE =  3,

  };

  /*

   * Read a range of bytes striped over one or more objects.  Iterate over
   * objects we stripe over.  (That's not atomic, but good enough for now.)
   *
   * If we get a short result from the OSD, check against i_size; we need to
   * only return a short read to the caller if we hit EOF.
   */
  static int striped_read(struct inode *inode,
  			u64 off, u64 len,

  			struct page **pages, int num_pages,

  			int *checkeof)

  {

  	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);

  	struct ceph_inode_info *ci = ceph_inode(inode);

  	u64 pos, this_len, left;

  	loff_t i_size;

  	int page_align, pages_left;
  	int read, ret;

  	struct page **page_pos;

  	bool hit_stripe, was_short;
  
  	/*
  	 * we may need to do multiple reads.  not atomic, unfortunately.
  	 */
  	pos = off;
  	left = len;
  	page_pos = pages;
  	pages_left = num_pages;
  	read = 0;
  
  more:

  	page_align = pos & ~PAGE_MASK;

  	this_len = left;

  	ret = ceph_osdc_readpages(&fsc->client->osdc, ceph_vino(inode),

  				  &ci->i_layout, pos, &this_len,
  				  ci->i_truncate_seq,
  				  ci->i_truncate_size,

  				  page_pos, pages_left, page_align);

  	if (ret == -ENOENT)
  		ret = 0;

  	hit_stripe = this_len < left;
  	was_short = ret >= 0 && ret < this_len;

  	dout("striped_read %llu~%llu (read %u) got %d%s%s
  ", pos, left, read,

  	     ret, hit_stripe ? " HITSTRIPE" : "", was_short ? " SHORT" : "");

  	i_size = i_size_read(inode);

  	if (ret >= 0) {
  		int didpages;

  		if (was_short && (pos + ret < i_size)) {
  			int zlen = min(this_len - ret, i_size - pos - ret);

  			int zoff = (off & ~PAGE_MASK) + read + ret;

  			dout(" zero gap %llu to %llu
  ",

  				pos + ret, pos + ret + zlen);
  			ceph_zero_page_vector_range(zoff, zlen, pages);
  			ret += zlen;

  		}

  		didpages = (page_align + ret) >> PAGE_SHIFT;

  		pos += ret;
  		read = pos - off;
  		left -= ret;
  		page_pos += didpages;
  		pages_left -= didpages;

  		/* hit stripe and need continue*/

  		if (left && hit_stripe && pos < i_size)

  			goto more;
  	}

  	if (read > 0) {

  		ret = read;

  		/* did we bounce off eof? */

  		if (pos + left > i_size)

  			*checkeof = CHECK_EOF;

  	}

  	dout("striped_read returns %d
  ", ret);
  	return ret;
  }
  
  /*
   * Completely synchronous read and write methods.  Direct from __user
   * buffer to osd, or directly to user pages (if O_DIRECT).
   *
   * If the read spans object boundary, just do multiple reads.
   */

  static ssize_t ceph_sync_read(struct kiocb *iocb, struct iov_iter *i,
  				int *checkeof)

  {

  	struct file *file = iocb->ki_filp;

  	struct inode *inode = file_inode(file);

  	struct page **pages;

  	u64 off = iocb->ki_pos;

  	int num_pages, ret;

  	size_t len = iov_iter_count(i);

  	dout("sync_read on file %p %llu~%u %s
  ", file, off,
  	     (unsigned)len,

  	     (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");

  
  	if (!len)
  		return 0;

  	/*
  	 * flush any page cache pages in this range.  this
  	 * will make concurrent normal and sync io slow,
  	 * but it will at least behave sensibly when they are
  	 * in sequence.
  	 */

  	ret = filemap_write_and_wait_range(inode->i_mapping, off,
  						off + len);

  	if (ret < 0)

  		return ret;

  	num_pages = calc_pages_for(off, len);
  	pages = ceph_alloc_page_vector(num_pages, GFP_KERNEL);
  	if (IS_ERR(pages))
  		return PTR_ERR(pages);
  	ret = striped_read(inode, off, len, pages,
  				num_pages, checkeof);
  	if (ret > 0) {
  		int l, k = 0;
  		size_t left = ret;
  
  		while (left) {
  			size_t page_off = off & ~PAGE_MASK;
  			size_t copy = min_t(size_t, left,
  					    PAGE_SIZE - page_off);
  			l = copy_page_to_iter(pages[k++], page_off, copy, i);
  			off += l;
  			left -= l;
  			if (l < copy)

  				break;
  		}

  	}

  	ceph_release_page_vector(pages, num_pages);

  	if (off > iocb->ki_pos) {
  		ret = off - iocb->ki_pos;
  		iocb->ki_pos = off;
  	}

  	dout("sync_read result %d
  ", ret);
  	return ret;
  }

  struct ceph_aio_request {
  	struct kiocb *iocb;
  	size_t total_len;
  	int write;
  	int error;
  	struct list_head osd_reqs;
  	unsigned num_reqs;
  	atomic_t pending_reqs;

  	struct timespec mtime;

  	struct ceph_cap_flush *prealloc_cf;
  };

  struct ceph_aio_work {
  	struct work_struct work;
  	struct ceph_osd_request *req;
  };
  
  static void ceph_aio_retry_work(struct work_struct *work);

  static void ceph_aio_complete(struct inode *inode,
  			      struct ceph_aio_request *aio_req)
  {
  	struct ceph_inode_info *ci = ceph_inode(inode);
  	int ret;
  
  	if (!atomic_dec_and_test(&aio_req->pending_reqs))
  		return;
  
  	ret = aio_req->error;
  	if (!ret)
  		ret = aio_req->total_len;
  
  	dout("ceph_aio_complete %p rc %d
  ", inode, ret);
  
  	if (ret >= 0 && aio_req->write) {
  		int dirty;
  
  		loff_t endoff = aio_req->iocb->ki_pos + aio_req->total_len;
  		if (endoff > i_size_read(inode)) {
  			if (ceph_inode_set_size(inode, endoff))
  				ceph_check_caps(ci, CHECK_CAPS_AUTHONLY, NULL);
  		}
  
  		spin_lock(&ci->i_ceph_lock);
  		ci->i_inline_version = CEPH_INLINE_NONE;
  		dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR,
  					       &aio_req->prealloc_cf);
  		spin_unlock(&ci->i_ceph_lock);
  		if (dirty)
  			__mark_inode_dirty(inode, dirty);
  
  	}
  
  	ceph_put_cap_refs(ci, (aio_req->write ? CEPH_CAP_FILE_WR :
  						CEPH_CAP_FILE_RD));
  
  	aio_req->iocb->ki_complete(aio_req->iocb, ret, 0);
  
  	ceph_free_cap_flush(aio_req->prealloc_cf);
  	kfree(aio_req);
  }

  static void ceph_aio_complete_req(struct ceph_osd_request *req)

  {
  	int rc = req->r_result;
  	struct inode *inode = req->r_inode;
  	struct ceph_aio_request *aio_req = req->r_priv;
  	struct ceph_osd_data *osd_data = osd_req_op_extent_osd_data(req, 0);
  	int num_pages = calc_pages_for((u64)osd_data->alignment,
  				       osd_data->length);
  
  	dout("ceph_aio_complete_req %p rc %d bytes %llu
  ",
  	     inode, rc, osd_data->length);
  
  	if (rc == -EOLDSNAPC) {

  		struct ceph_aio_work *aio_work;
  		BUG_ON(!aio_req->write);
  
  		aio_work = kmalloc(sizeof(*aio_work), GFP_NOFS);
  		if (aio_work) {
  			INIT_WORK(&aio_work->work, ceph_aio_retry_work);
  			aio_work->req = req;
  			queue_work(ceph_inode_to_client(inode)->wb_wq,
  				   &aio_work->work);
  			return;
  		}
  		rc = -ENOMEM;
  	} else if (!aio_req->write) {

  		if (rc == -ENOENT)
  			rc = 0;
  		if (rc >= 0 && osd_data->length > rc) {
  			int zoff = osd_data->alignment + rc;
  			int zlen = osd_data->length - rc;
  			/*
  			 * If read is satisfied by single OSD request,
  			 * it can pass EOF. Otherwise read is within
  			 * i_size.
  			 */
  			if (aio_req->num_reqs == 1) {
  				loff_t i_size = i_size_read(inode);
  				loff_t endoff = aio_req->iocb->ki_pos + rc;
  				if (endoff < i_size)
  					zlen = min_t(size_t, zlen,
  						     i_size - endoff);
  				aio_req->total_len = rc + zlen;
  			}
  
  			if (zlen > 0)
  				ceph_zero_page_vector_range(zoff, zlen,
  							    osd_data->pages);
  		}
  	}

  	ceph_put_page_vector(osd_data->pages, num_pages, !aio_req->write);

  	ceph_osdc_put_request(req);
  
  	if (rc < 0)
  		cmpxchg(&aio_req->error, 0, rc);
  
  	ceph_aio_complete(inode, aio_req);
  	return;
  }

  static void ceph_aio_retry_work(struct work_struct *work)
  {
  	struct ceph_aio_work *aio_work =
  		container_of(work, struct ceph_aio_work, work);
  	struct ceph_osd_request *orig_req = aio_work->req;
  	struct ceph_aio_request *aio_req = orig_req->r_priv;
  	struct inode *inode = orig_req->r_inode;
  	struct ceph_inode_info *ci = ceph_inode(inode);
  	struct ceph_snap_context *snapc;
  	struct ceph_osd_request *req;
  	int ret;
  
  	spin_lock(&ci->i_ceph_lock);
  	if (__ceph_have_pending_cap_snap(ci)) {
  		struct ceph_cap_snap *capsnap =
  			list_last_entry(&ci->i_cap_snaps,
  					struct ceph_cap_snap,
  					ci_item);
  		snapc = ceph_get_snap_context(capsnap->context);
  	} else {
  		BUG_ON(!ci->i_head_snapc);
  		snapc = ceph_get_snap_context(ci->i_head_snapc);
  	}
  	spin_unlock(&ci->i_ceph_lock);
  
  	req = ceph_osdc_alloc_request(orig_req->r_osdc, snapc, 2,
  			false, GFP_NOFS);

  	if (!req) {
  		ret = -ENOMEM;

  		req = orig_req;
  		goto out;
  	}
  
  	req->r_flags =	CEPH_OSD_FLAG_ORDERSNAP |
  			CEPH_OSD_FLAG_ONDISK |
  			CEPH_OSD_FLAG_WRITE;

  	ceph_oloc_copy(&req->r_base_oloc, &orig_req->r_base_oloc);

  	ceph_oid_copy(&req->r_base_oid, &orig_req->r_base_oid);

  	ret = ceph_osdc_alloc_messages(req, GFP_NOFS);
  	if (ret) {
  		ceph_osdc_put_request(req);
  		req = orig_req;
  		goto out;
  	}

  
  	req->r_ops[0] = orig_req->r_ops[0];
  	osd_req_op_init(req, 1, CEPH_OSD_OP_STARTSYNC, 0);

  	req->r_mtime = aio_req->mtime;
  	req->r_data_offset = req->r_ops[0].extent.offset;

  	ceph_osdc_put_request(orig_req);
  
  	req->r_callback = ceph_aio_complete_req;
  	req->r_inode = inode;
  	req->r_priv = aio_req;
  
  	ret = ceph_osdc_start_request(req->r_osdc, req, false);
  out:
  	if (ret < 0) {

  		req->r_result = ret;

  		ceph_aio_complete_req(req);

  	}

  	ceph_put_snap_context(snapc);

  	kfree(aio_work);
  }

  /*

   * Write commit request unsafe callback, called to tell us when a
   * request is unsafe (that is, in flight--has been handed to the
   * messenger to send to its target osd).  It is called again when
   * we've received a response message indicating the request is
   * "safe" (its CEPH_OSD_FLAG_ONDISK flag is set), or when a request
   * is completed early (and unsuccessfully) due to a timeout or
   * interrupt.
   *
   * This is used if we requested both an ACK and ONDISK commit reply
   * from the OSD.

   */

  static void ceph_sync_write_unsafe(struct ceph_osd_request *req, bool unsafe)

  {
  	struct ceph_inode_info *ci = ceph_inode(req->r_inode);

  	dout("%s %p tid %llu %ssafe
  ", __func__, req, req->r_tid,
  		unsafe ? "un" : "");
  	if (unsafe) {
  		ceph_get_cap_refs(ci, CEPH_CAP_FILE_WR);
  		spin_lock(&ci->i_unsafe_lock);
  		list_add_tail(&req->r_unsafe_item,
  			      &ci->i_unsafe_writes);
  		spin_unlock(&ci->i_unsafe_lock);

  
  		complete_all(&req->r_completion);

  	} else {
  		spin_lock(&ci->i_unsafe_lock);
  		list_del_init(&req->r_unsafe_item);
  		spin_unlock(&ci->i_unsafe_lock);
  		ceph_put_cap_refs(ci, CEPH_CAP_FILE_WR);
  	}

  }

  /*
   * Wait on any unsafe replies for the given inode.  First wait on the
   * newest request, and make that the upper bound.  Then, if there are
   * more requests, keep waiting on the oldest as long as it is still older
   * than the original request.
   */
  void ceph_sync_write_wait(struct inode *inode)
  {
  	struct ceph_inode_info *ci = ceph_inode(inode);
  	struct list_head *head = &ci->i_unsafe_writes;
  	struct ceph_osd_request *req;
  	u64 last_tid;
  
  	if (!S_ISREG(inode->i_mode))
  		return;
  
  	spin_lock(&ci->i_unsafe_lock);
  	if (list_empty(head))
  		goto out;
  
  	/* set upper bound as _last_ entry in chain */
  
  	req = list_last_entry(head, struct ceph_osd_request,
  			      r_unsafe_item);
  	last_tid = req->r_tid;
  
  	do {
  		ceph_osdc_get_request(req);
  		spin_unlock(&ci->i_unsafe_lock);
  
  		dout("sync_write_wait on tid %llu (until %llu)
  ",
  		     req->r_tid, last_tid);
  		wait_for_completion(&req->r_safe_completion);
  		ceph_osdc_put_request(req);
  
  		spin_lock(&ci->i_unsafe_lock);
  		/*
  		 * from here on look at first entry in chain, since we
  		 * only want to wait for anything older than last_tid
  		 */
  		if (list_empty(head))
  			break;
  		req = list_first_entry(head, struct ceph_osd_request,
  				       r_unsafe_item);
  	} while (req->r_tid < last_tid);
  out:
  	spin_unlock(&ci->i_unsafe_lock);
  }

  static ssize_t

  ceph_direct_read_write(struct kiocb *iocb, struct iov_iter *iter,
  		       struct ceph_snap_context *snapc,
  		       struct ceph_cap_flush **pcf)

  {

  	struct file *file = iocb->ki_filp;

  	struct inode *inode = file_inode(file);

  	struct ceph_inode_info *ci = ceph_inode(inode);

  	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);

  	struct ceph_vino vino;

  	struct ceph_osd_request *req;
  	struct page **pages;

  	struct ceph_aio_request *aio_req = NULL;
  	int num_pages = 0;

  	int flags;

  	int ret;

  	struct timespec mtime = current_time(inode);

  	size_t count = iov_iter_count(iter);
  	loff_t pos = iocb->ki_pos;
  	bool write = iov_iter_rw(iter) == WRITE;

  	if (write && ceph_snap(file_inode(file)) != CEPH_NOSNAP)

  		return -EROFS;

  	dout("sync_direct_read_write (%s) on file %p %lld~%u
  ",
  	     (write ? "write" : "read"), file, pos, (unsigned)count);

  	ret = filemap_write_and_wait_range(inode->i_mapping, pos, pos + count);

  	if (ret < 0)
  		return ret;

  	if (write) {

  		int ret2 = invalidate_inode_pages2_range(inode->i_mapping,

  					pos >> PAGE_SHIFT,
  					(pos + count) >> PAGE_SHIFT);

  		if (ret2 < 0)

  			dout("invalidate_inode_pages2_range returned %d
  ", ret);

  		flags = CEPH_OSD_FLAG_ORDERSNAP |
  			CEPH_OSD_FLAG_ONDISK |
  			CEPH_OSD_FLAG_WRITE;
  	} else {
  		flags = CEPH_OSD_FLAG_READ;
  	}

  	while (iov_iter_count(iter) > 0) {
  		u64 size = dio_get_pagev_size(iter);
  		size_t start = 0;
  		ssize_t len;

  		vino = ceph_vino(inode);
  		req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,

  					    vino, pos, &size, 0,
  					    /*include a 'startsync' command*/
  					    write ? 2 : 1,
  					    write ? CEPH_OSD_OP_WRITE :
  						    CEPH_OSD_OP_READ,
  					    flags, snapc,

  					    ci->i_truncate_seq,
  					    ci->i_truncate_size,
  					    false);
  		if (IS_ERR(req)) {
  			ret = PTR_ERR(req);

  			break;

  		}

  		len = size;
  		pages = dio_get_pages_alloc(iter, len, &start, &num_pages);

  		if (IS_ERR(pages)) {

  			ceph_osdc_put_request(req);

  			ret = PTR_ERR(pages);

  			break;

  		}
  
  		/*

  		 * To simplify error handling, allow AIO when IO within i_size
  		 * or IO can be satisfied by single OSD request.

  		 */

  		if (pos == iocb->ki_pos && !is_sync_kiocb(iocb) &&
  		    (len == count || pos + count <= i_size_read(inode))) {
  			aio_req = kzalloc(sizeof(*aio_req), GFP_KERNEL);
  			if (aio_req) {
  				aio_req->iocb = iocb;
  				aio_req->write = write;
  				INIT_LIST_HEAD(&aio_req->osd_reqs);
  				if (write) {

  					aio_req->mtime = mtime;

  					swap(aio_req->prealloc_cf, *pcf);
  				}
  			}
  			/* ignore error */
  		}
  
  		if (write) {
  			/*
  			 * throw out any page cache pages in this range. this
  			 * may block.
  			 */
  			truncate_inode_pages_range(inode->i_mapping, pos,

  					(pos+len) | (PAGE_SIZE - 1));

  
  			osd_req_op_init(req, 1, CEPH_OSD_OP_STARTSYNC, 0);

  			req->r_mtime = mtime;

  		}

  		osd_req_op_extent_osd_data_pages(req, 0, pages, len, start,
  						 false, false);

  		if (aio_req) {
  			aio_req->total_len += len;
  			aio_req->num_reqs++;
  			atomic_inc(&aio_req->pending_reqs);
  
  			req->r_callback = ceph_aio_complete_req;
  			req->r_inode = inode;
  			req->r_priv = aio_req;
  			list_add_tail(&req->r_unsafe_item, &aio_req->osd_reqs);
  
  			pos += len;
  			iov_iter_advance(iter, len);
  			continue;
  		}
  
  		ret = ceph_osdc_start_request(req->r_osdc, req, false);

  		if (!ret)
  			ret = ceph_osdc_wait_request(&fsc->client->osdc, req);

  		size = i_size_read(inode);
  		if (!write) {
  			if (ret == -ENOENT)
  				ret = 0;
  			if (ret >= 0 && ret < len && pos + ret < size) {
  				int zlen = min_t(size_t, len - ret,
  						 size - pos - ret);
  				ceph_zero_page_vector_range(start + ret, zlen,
  							    pages);
  				ret += zlen;
  			}
  			if (ret >= 0)
  				len = ret;
  		}

  		ceph_put_page_vector(pages, num_pages, !write);

  		ceph_osdc_put_request(req);

  		if (ret < 0)

  			break;

  		pos += len;
  		iov_iter_advance(iter, len);
  
  		if (!write && pos >= size)

  			break;

  		if (write && pos > size) {
  			if (ceph_inode_set_size(inode, pos))

  				ceph_check_caps(ceph_inode(inode),
  						CHECK_CAPS_AUTHONLY,
  						NULL);
  		}

  	}

  	if (aio_req) {

  		LIST_HEAD(osd_reqs);

  		if (aio_req->num_reqs == 0) {
  			kfree(aio_req);
  			return ret;
  		}
  
  		ceph_get_cap_refs(ci, write ? CEPH_CAP_FILE_WR :
  					      CEPH_CAP_FILE_RD);

  		list_splice(&aio_req->osd_reqs, &osd_reqs);
  		while (!list_empty(&osd_reqs)) {
  			req = list_first_entry(&osd_reqs,

  					       struct ceph_osd_request,
  					       r_unsafe_item);
  			list_del_init(&req->r_unsafe_item);
  			if (ret >= 0)
  				ret = ceph_osdc_start_request(req->r_osdc,
  							      req, false);
  			if (ret < 0) {
  				req->r_result = ret;

  				ceph_aio_complete_req(req);

  			}
  		}
  		return -EIOCBQUEUED;
  	}
  
  	if (ret != -EOLDSNAPC && pos > iocb->ki_pos) {
  		ret = pos - iocb->ki_pos;

  		iocb->ki_pos = pos;

  	}
  	return ret;
  }

  /*
   * Synchronous write, straight from __user pointer or user pages.
   *
   * If write spans object boundary, just do multiple writes.  (For a
   * correct atomic write, we should e.g. take write locks on all
   * objects, rollback on failure, etc.)
   */

  static ssize_t

  ceph_sync_write(struct kiocb *iocb, struct iov_iter *from, loff_t pos,
  		struct ceph_snap_context *snapc)

  {
  	struct file *file = iocb->ki_filp;
  	struct inode *inode = file_inode(file);
  	struct ceph_inode_info *ci = ceph_inode(inode);
  	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);

  	struct ceph_vino vino;
  	struct ceph_osd_request *req;
  	struct page **pages;
  	u64 len;
  	int num_pages;
  	int written = 0;
  	int flags;
  	int check_caps = 0;
  	int ret;

  	struct timespec mtime = current_time(inode);

  	size_t count = iov_iter_count(from);

  
  	if (ceph_snap(file_inode(file)) != CEPH_NOSNAP)
  		return -EROFS;
  
  	dout("sync_write on file %p %lld~%u
  ", file, pos, (unsigned)count);
  
  	ret = filemap_write_and_wait_range(inode->i_mapping, pos, pos + count);
  	if (ret < 0)
  		return ret;
  
  	ret = invalidate_inode_pages2_range(inode->i_mapping,

  					    pos >> PAGE_SHIFT,
  					    (pos + count) >> PAGE_SHIFT);

  	if (ret < 0)
  		dout("invalidate_inode_pages2_range returned %d
  ", ret);
  
  	flags = CEPH_OSD_FLAG_ORDERSNAP |
  		CEPH_OSD_FLAG_ONDISK |
  		CEPH_OSD_FLAG_WRITE |
  		CEPH_OSD_FLAG_ACK;

  	while ((len = iov_iter_count(from)) > 0) {

  		size_t left;
  		int n;

  		vino = ceph_vino(inode);
  		req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,

  					    vino, pos, &len, 0, 1,

  					    CEPH_OSD_OP_WRITE, flags, snapc,
  					    ci->i_truncate_seq,
  					    ci->i_truncate_size,
  					    false);
  		if (IS_ERR(req)) {
  			ret = PTR_ERR(req);

  			break;

  		}
  
  		/*
  		 * write from beginning of first page,
  		 * regardless of io alignment
  		 */

  		num_pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;

  		pages = ceph_alloc_page_vector(num_pages, GFP_KERNEL);

  		if (IS_ERR(pages)) {
  			ret = PTR_ERR(pages);
  			goto out;
  		}

  
  		left = len;
  		for (n = 0; n < num_pages; n++) {

  			size_t plen = min_t(size_t, left, PAGE_SIZE);

  			ret = copy_page_from_iter(pages[n], 0, plen, from);

  			if (ret != plen) {
  				ret = -EFAULT;
  				break;
  			}
  			left -= ret;

  		}

  		if (ret < 0) {
  			ceph_release_page_vector(pages, num_pages);
  			goto out;
  		}

  		/* get a second commit callback */
  		req->r_unsafe_callback = ceph_sync_write_unsafe;
  		req->r_inode = inode;

  		osd_req_op_extent_osd_data_pages(req, 0, pages, len, 0,
  						false, true);

  		req->r_mtime = mtime;

  		ret = ceph_osdc_start_request(&fsc->client->osdc, req, false);
  		if (!ret)
  			ret = ceph_osdc_wait_request(&fsc->client->osdc, req);

  
  out:

  		ceph_osdc_put_request(req);
  		if (ret == 0) {
  			pos += len;
  			written += len;
  
  			if (pos > i_size_read(inode)) {
  				check_caps = ceph_inode_set_size(inode, pos);
  				if (check_caps)
  					ceph_check_caps(ceph_inode(inode),
  							CHECK_CAPS_AUTHONLY,
  							NULL);
  			}
  		} else
  			break;
  	}

  	if (ret != -EOLDSNAPC && written > 0) {

  		ret = written;

  		iocb->ki_pos = pos;

  	}
  	return ret;
  }
  
  /*
   * Wrap generic_file_aio_read with checks for cap bits on the inode.
   * Atomically grab references, so that those bits are not released
   * back to the MDS mid-read.
   *
   * Hmm, the sync read case isn't actually async... should it be?
   */

  static ssize_t ceph_read_iter(struct kiocb *iocb, struct iov_iter *to)

  {
  	struct file *filp = iocb->ki_filp;

  	struct ceph_file_info *fi = filp->private_data;

  	size_t len = iov_iter_count(to);

  	struct inode *inode = file_inode(filp);

  	struct ceph_inode_info *ci = ceph_inode(inode);

  	struct page *pinned_page = NULL;

  	ssize_t ret;

  	int want, got = 0;

  	int retry_op = 0, read = 0;

  again:

  	dout("aio_read %p %llx.%llx %llu~%u trying to get caps on %p
  ",
  	     inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len, inode);

  	if (fi->fmode & CEPH_FILE_MODE_LAZY)
  		want = CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO;
  	else
  		want = CEPH_CAP_FILE_CACHE;

  	ret = ceph_get_caps(ci, CEPH_CAP_FILE_RD, want, -1, &got, &pinned_page);

  	if (ret < 0)

  		return ret;

  	if ((got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0 ||

  	    (iocb->ki_flags & IOCB_DIRECT) ||

  	    (fi->flags & CEPH_F_SYNC)) {

  
  		dout("aio_sync_read %p %llx.%llx %llu~%u got cap refs on %s
  ",
  		     inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len,
  		     ceph_cap_string(got));

  		if (ci->i_inline_version == CEPH_INLINE_NONE) {

  			if (!retry_op && (iocb->ki_flags & IOCB_DIRECT)) {
  				ret = ceph_direct_read_write(iocb, to,
  							     NULL, NULL);
  				if (ret >= 0 && ret < len)
  					retry_op = CHECK_EOF;
  			} else {
  				ret = ceph_sync_read(iocb, to, &retry_op);
  			}

  		} else {
  			retry_op = READ_INLINE;
  		}

  	} else {

  		dout("aio_read %p %llx.%llx %llu~%u got cap refs on %s
  ",

  		     inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len,

  		     ceph_cap_string(got));

  		ret = generic_file_read_iter(iocb, to);

  	}

  	dout("aio_read %p %llx.%llx dropping cap refs on %s = %d
  ",
  	     inode, ceph_vinop(inode), ceph_cap_string(got), (int)ret);

  	if (pinned_page) {

  		put_page(pinned_page);

  		pinned_page = NULL;
  	}

  	ceph_put_cap_refs(ci, got);

  	if (retry_op > HAVE_RETRIED && ret >= 0) {

  		int statret;
  		struct page *page = NULL;
  		loff_t i_size;
  		if (retry_op == READ_INLINE) {

  			page = __page_cache_alloc(GFP_KERNEL);

  			if (!page)
  				return -ENOMEM;
  		}

  		statret = __ceph_do_getattr(inode, page,
  					    CEPH_STAT_CAP_INLINE_DATA, !!page);
  		if (statret < 0) {

  			if (page)
  				__free_page(page);

  			if (statret == -ENODATA) {
  				BUG_ON(retry_op != READ_INLINE);
  				goto again;
  			}
  			return statret;
  		}

  		i_size = i_size_read(inode);
  		if (retry_op == READ_INLINE) {

  			BUG_ON(ret > 0 || read > 0);
  			if (iocb->ki_pos < i_size &&

  			    iocb->ki_pos < PAGE_SIZE) {

  				loff_t end = min_t(loff_t, i_size,
  						   iocb->ki_pos + len);

  				end = min_t(loff_t, end, PAGE_SIZE);

  				if (statret < end)
  					zero_user_segment(page, statret, end);
  				ret = copy_page_to_iter(page,
  						iocb->ki_pos & ~PAGE_MASK,
  						end - iocb->ki_pos, to);
  				iocb->ki_pos += ret;

  				read += ret;
  			}
  			if (iocb->ki_pos < i_size && read < len) {
  				size_t zlen = min_t(size_t, len - read,
  						    i_size - iocb->ki_pos);
  				ret = iov_iter_zero(zlen, to);
  				iocb->ki_pos += ret;
  				read += ret;

  			}
  			__free_pages(page, 0);

  			return read;

  		}

  
  		/* hit EOF or hole? */

  		if (retry_op == CHECK_EOF && iocb->ki_pos < i_size &&

  		    ret < len) {

  			dout("sync_read hit hole, ppos %lld < size %lld"

  			     ", reading more
  ", iocb->ki_pos, i_size);

  			read += ret;

  			len -= ret;

  			retry_op = HAVE_RETRIED;

  			goto again;
  		}
  	}

  	if (ret >= 0)
  		ret += read;

  	return ret;
  }
  
  /*
   * Take cap references to avoid releasing caps to MDS mid-write.
   *
   * If we are synchronous, and write with an old snap context, the OSD
   * may return EOLDSNAPC.  In that case, retry the write.. _after_
   * dropping our cap refs and allowing the pending snap to logically
   * complete _before_ this write occurs.
   *
   * If we are near ENOSPC, write synchronously.
   */

  static ssize_t ceph_write_iter(struct kiocb *iocb, struct iov_iter *from)

  {
  	struct file *file = iocb->ki_filp;

  	struct ceph_file_info *fi = file->private_data;

  	struct inode *inode = file_inode(file);

  	struct ceph_inode_info *ci = ceph_inode(inode);

  	struct ceph_osd_client *osdc =
  		&ceph_sb_to_client(inode->i_sb)->client->osdc;

  	struct ceph_cap_flush *prealloc_cf;

  	ssize_t count, written = 0;

  	int err, want, got;

  	loff_t pos;

  
  	if (ceph_snap(inode) != CEPH_NOSNAP)
  		return -EROFS;

  	prealloc_cf = ceph_alloc_cap_flush();
  	if (!prealloc_cf)
  		return -ENOMEM;

  	inode_lock(inode);

  	/* We can write back this queue in page reclaim */

  	current->backing_dev_info = inode_to_bdi(inode);

  	if (iocb->ki_flags & IOCB_APPEND) {
  		err = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE, false);
  		if (err < 0)
  			goto out;
  	}

  	err = generic_write_checks(iocb, from);
  	if (err <= 0)

  		goto out;

  	pos = iocb->ki_pos;
  	count = iov_iter_count(from);

  	err = file_remove_privs(file);

  	if (err)
  		goto out;
  
  	err = file_update_time(file);
  	if (err)
  		goto out;

  	if (ci->i_inline_version != CEPH_INLINE_NONE) {
  		err = ceph_uninline_data(file, NULL);
  		if (err < 0)
  			goto out;
  	}

  retry_snap:

  	if (ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL)) {

  		err = -ENOSPC;

  		goto out;
  	}

  	dout("aio_write %p %llx.%llx %llu~%zd getting caps. i_size %llu
  ",

  	     inode, ceph_vinop(inode), pos, count, i_size_read(inode));

  	if (fi->fmode & CEPH_FILE_MODE_LAZY)
  		want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
  	else
  		want = CEPH_CAP_FILE_BUFFER;

  	got = 0;

  	err = ceph_get_caps(ci, CEPH_CAP_FILE_WR, want, pos + count,
  			    &got, NULL);

  	if (err < 0)

  		goto out;

  	dout("aio_write %p %llx.%llx %llu~%zd got cap refs on %s
  ",

  	     inode, ceph_vinop(inode), pos, count, ceph_cap_string(got));

  
  	if ((got & (CEPH_CAP_FILE_BUFFER|CEPH_CAP_FILE_LAZYIO)) == 0 ||

  	    (iocb->ki_flags & IOCB_DIRECT) || (fi->flags & CEPH_F_SYNC)) {

  		struct ceph_snap_context *snapc;

  		struct iov_iter data;

  		inode_unlock(inode);

  
  		spin_lock(&ci->i_ceph_lock);
  		if (__ceph_have_pending_cap_snap(ci)) {
  			struct ceph_cap_snap *capsnap =
  					list_last_entry(&ci->i_cap_snaps,
  							struct ceph_cap_snap,
  							ci_item);
  			snapc = ceph_get_snap_context(capsnap->context);
  		} else {
  			BUG_ON(!ci->i_head_snapc);
  			snapc = ceph_get_snap_context(ci->i_head_snapc);
  		}
  		spin_unlock(&ci->i_ceph_lock);

  		/* we might need to revert back to that point */
  		data = *from;

  		if (iocb->ki_flags & IOCB_DIRECT)

  			written = ceph_direct_read_write(iocb, &data, snapc,
  							 &prealloc_cf);

  		else

  			written = ceph_sync_write(iocb, &data, pos, snapc);

  		if (written == -EOLDSNAPC) {
  			dout("aio_write %p %llx.%llx %llu~%u"
  				"got EOLDSNAPC, retrying
  ",
  				inode, ceph_vinop(inode),

  				pos, (unsigned)count);

  			inode_lock(inode);

  			goto retry_snap;
  		}

  		if (written > 0)
  			iov_iter_advance(from, written);

  		ceph_put_snap_context(snapc);

  	} else {

  		/*
  		 * No need to acquire the i_truncate_mutex. Because
  		 * the MDS revokes Fwb caps before sending truncate
  		 * message to us. We can't get Fwb cap while there
  		 * are pending vmtruncate. So write and vmtruncate
  		 * can not run at the same time
  		 */

  		written = generic_perform_write(file, from, pos);

  		if (likely(written >= 0))
  			iocb->ki_pos = pos + written;

  		inode_unlock(inode);

  	}

  	if (written >= 0) {

  		int dirty;

  		spin_lock(&ci->i_ceph_lock);

  		ci->i_inline_version = CEPH_INLINE_NONE;

  		dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR,
  					       &prealloc_cf);

  		spin_unlock(&ci->i_ceph_lock);

  		if (dirty)
  			__mark_inode_dirty(inode, dirty);

  	}

  	dout("aio_write %p %llx.%llx %llu~%u  dropping cap refs on %s
  ",

  	     inode, ceph_vinop(inode), pos, (unsigned)count,

  	     ceph_cap_string(got));

  	ceph_put_cap_refs(ci, got);

  	if (written >= 0) {

  		if (ceph_osdmap_flag(osdc, CEPH_OSDMAP_NEARFULL))

  			iocb->ki_flags |= IOCB_DSYNC;
  
  		written = generic_write_sync(iocb, written);

  	}

  	goto out_unlocked;

  out:

  	inode_unlock(inode);

  out_unlocked:

  	ceph_free_cap_flush(prealloc_cf);

  	current->backing_dev_info = NULL;

  	return written ? written : err;

  }
  
  /*
   * llseek.  be sure to verify file size on SEEK_END.
   */

  static loff_t ceph_llseek(struct file *file, loff_t offset, int whence)

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

  	loff_t i_size;

  	loff_t ret;

  	inode_lock(inode);

  	if (whence == SEEK_END || whence == SEEK_DATA || whence == SEEK_HOLE) {

  		ret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE, false);

  		if (ret < 0)

  			goto out;

  	}

  	i_size = i_size_read(inode);

  	switch (whence) {

  	case SEEK_END:

  		offset += i_size;

  		break;
  	case SEEK_CUR:
  		/*
  		 * Here we special-case the lseek(fd, 0, SEEK_CUR)
  		 * position-querying operation.  Avoid rewriting the "same"
  		 * f_pos value back to the file because a concurrent read(),
  		 * write() or lseek() might have altered it
  		 */
  		if (offset == 0) {

  			ret = file->f_pos;

  			goto out;
  		}
  		offset += file->f_pos;
  		break;

  	case SEEK_DATA:

  		if (offset >= i_size) {

  			ret = -ENXIO;
  			goto out;
  		}
  		break;
  	case SEEK_HOLE:

  		if (offset >= i_size) {

  			ret = -ENXIO;
  			goto out;
  		}

  		offset = i_size;

  		break;

  	}

  	ret = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);

  
  out:

  	inode_unlock(inode);

  	return ret;

  }

  static inline void ceph_zero_partial_page(
  	struct inode *inode, loff_t offset, unsigned size)
  {
  	struct page *page;

  	pgoff_t index = offset >> PAGE_SHIFT;

  
  	page = find_lock_page(inode->i_mapping, index);
  	if (page) {
  		wait_on_page_writeback(page);

  		zero_user(page, offset & (PAGE_SIZE - 1), size);

  		unlock_page(page);

  		put_page(page);

  	}
  }
  
  static void ceph_zero_pagecache_range(struct inode *inode, loff_t offset,
  				      loff_t length)
  {

  	loff_t nearly = round_up(offset, PAGE_SIZE);

  	if (offset < nearly) {
  		loff_t size = nearly - offset;
  		if (length < size)
  			size = length;
  		ceph_zero_partial_page(inode, offset, size);
  		offset += size;
  		length -= size;
  	}

  	if (length >= PAGE_SIZE) {
  		loff_t size = round_down(length, PAGE_SIZE);

  		truncate_pagecache_range(inode, offset, offset + size - 1);
  		offset += size;
  		length -= size;
  	}
  	if (length)
  		ceph_zero_partial_page(inode, offset, length);
  }
  
  static int ceph_zero_partial_object(struct inode *inode,
  				    loff_t offset, loff_t *length)
  {
  	struct ceph_inode_info *ci = ceph_inode(inode);
  	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
  	struct ceph_osd_request *req;
  	int ret = 0;
  	loff_t zero = 0;
  	int op;
  
  	if (!length) {
  		op = offset ? CEPH_OSD_OP_DELETE : CEPH_OSD_OP_TRUNCATE;
  		length = &zero;
  	} else {
  		op = CEPH_OSD_OP_ZERO;
  	}
  
  	req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
  					ceph_vino(inode),
  					offset, length,

  					0, 1, op,

  					CEPH_OSD_FLAG_WRITE |
  					CEPH_OSD_FLAG_ONDISK,
  					NULL, 0, 0, false);
  	if (IS_ERR(req)) {
  		ret = PTR_ERR(req);
  		goto out;
  	}

  	req->r_mtime = inode->i_mtime;

  	ret = ceph_osdc_start_request(&fsc->client->osdc, req, false);
  	if (!ret) {
  		ret = ceph_osdc_wait_request(&fsc->client->osdc, req);
  		if (ret == -ENOENT)
  			ret = 0;
  	}
  	ceph_osdc_put_request(req);
  
  out:
  	return ret;
  }
  
  static int ceph_zero_objects(struct inode *inode, loff_t offset, loff_t length)
  {
  	int ret = 0;
  	struct ceph_inode_info *ci = ceph_inode(inode);

  	s32 stripe_unit = ci->i_layout.stripe_unit;
  	s32 stripe_count = ci->i_layout.stripe_count;
  	s32 object_size = ci->i_layout.object_size;

  	u64 object_set_size = object_size * stripe_count;
  	u64 nearly, t;
  
  	/* round offset up to next period boundary */
  	nearly = offset + object_set_size - 1;
  	t = nearly;
  	nearly -= do_div(t, object_set_size);

  	while (length && offset < nearly) {
  		loff_t size = length;
  		ret = ceph_zero_partial_object(inode, offset, &size);
  		if (ret < 0)
  			return ret;
  		offset += size;
  		length -= size;
  	}
  	while (length >= object_set_size) {
  		int i;
  		loff_t pos = offset;
  		for (i = 0; i < stripe_count; ++i) {
  			ret = ceph_zero_partial_object(inode, pos, NULL);
  			if (ret < 0)
  				return ret;
  			pos += stripe_unit;
  		}
  		offset += object_set_size;
  		length -= object_set_size;
  	}
  	while (length) {
  		loff_t size = length;
  		ret = ceph_zero_partial_object(inode, offset, &size);
  		if (ret < 0)
  			return ret;
  		offset += size;
  		length -= size;
  	}
  	return ret;
  }
  
  static long ceph_fallocate(struct file *file, int mode,
  				loff_t offset, loff_t length)
  {
  	struct ceph_file_info *fi = file->private_data;

  	struct inode *inode = file_inode(file);

  	struct ceph_inode_info *ci = ceph_inode(inode);
  	struct ceph_osd_client *osdc =
  		&ceph_inode_to_client(inode)->client->osdc;

  	struct ceph_cap_flush *prealloc_cf;

  	int want, got = 0;
  	int dirty;
  	int ret = 0;
  	loff_t endoff = 0;
  	loff_t size;

  	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
  		return -EOPNOTSUPP;

  	if (!S_ISREG(inode->i_mode))
  		return -EOPNOTSUPP;

  	prealloc_cf = ceph_alloc_cap_flush();
  	if (!prealloc_cf)
  		return -ENOMEM;

  	inode_lock(inode);

  
  	if (ceph_snap(inode) != CEPH_NOSNAP) {
  		ret = -EROFS;
  		goto unlock;
  	}

  	if (ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL) &&
  	    !(mode & FALLOC_FL_PUNCH_HOLE)) {

  		ret = -ENOSPC;
  		goto unlock;
  	}

  	if (ci->i_inline_version != CEPH_INLINE_NONE) {
  		ret = ceph_uninline_data(file, NULL);
  		if (ret < 0)
  			goto unlock;
  	}

  	size = i_size_read(inode);
  	if (!(mode & FALLOC_FL_KEEP_SIZE))
  		endoff = offset + length;
  
  	if (fi->fmode & CEPH_FILE_MODE_LAZY)
  		want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
  	else
  		want = CEPH_CAP_FILE_BUFFER;

  	ret = ceph_get_caps(ci, CEPH_CAP_FILE_WR, want, endoff, &got, NULL);

  	if (ret < 0)
  		goto unlock;
  
  	if (mode & FALLOC_FL_PUNCH_HOLE) {
  		if (offset < size)
  			ceph_zero_pagecache_range(inode, offset, length);
  		ret = ceph_zero_objects(inode, offset, length);
  	} else if (endoff > size) {
  		truncate_pagecache_range(inode, size, -1);
  		if (ceph_inode_set_size(inode, endoff))
  			ceph_check_caps(ceph_inode(inode),
  				CHECK_CAPS_AUTHONLY, NULL);
  	}
  
  	if (!ret) {
  		spin_lock(&ci->i_ceph_lock);

  		ci->i_inline_version = CEPH_INLINE_NONE;

  		dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR,
  					       &prealloc_cf);

  		spin_unlock(&ci->i_ceph_lock);
  		if (dirty)
  			__mark_inode_dirty(inode, dirty);
  	}
  
  	ceph_put_cap_refs(ci, got);
  unlock:

  	inode_unlock(inode);

  	ceph_free_cap_flush(prealloc_cf);

  	return ret;
  }

  const struct file_operations ceph_file_fops = {
  	.open = ceph_open,
  	.release = ceph_release,
  	.llseek = ceph_llseek,

  	.read_iter = ceph_read_iter,

  	.write_iter = ceph_write_iter,

  	.mmap = ceph_mmap,
  	.fsync = ceph_fsync,

  	.lock = ceph_lock,
  	.flock = ceph_flock,

  	.splice_write = iter_file_splice_write,

  	.unlocked_ioctl = ceph_ioctl,
  	.compat_ioctl	= ceph_ioctl,

  	.fallocate	= ceph_fallocate,

  };