#include <linux/ceph/ceph_debug.h>

  #include <linux/module.h>

  #include <linux/sched.h>

  #include <linux/slab.h>

  #include <linux/file.h>
  #include <linux/namei.h>
  #include <linux/writeback.h>
  
  #include "super.h"
  #include "mds_client.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.
   */
  
  
  /*
   * 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);

  	req->r_args.open.preferred = cpu_to_le32(-1);

  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:
  	case S_IFDIR:
  		dout("init_file %p %p 0%o (regular)
  ", inode, file,
  		     inode->i_mode);
  		cf = kmem_cache_alloc(ceph_file_cachep, GFP_NOFS | __GFP_ZERO);
  		if (cf == NULL) {
  			ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
  			return -ENOMEM;
  		}
  		cf->fmode = fmode;
  		cf->next_offset = 2;
  		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;
  }
  
  /*
   * If the filp already has private_data, that means the file was
   * already opened by intent during lookup, and we do nothing.
   *
   * 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;

  	struct inode *parent_inode = NULL;

  	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;

  	if (flags & (O_CREAT|O_TRUNC))
  		parent_inode = ceph_get_dentry_parent_inode(file->f_dentry);

  	err = ceph_mdsc_do_request(mdsc, parent_inode, req);

  	iput(parent_inode);

  	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 this succeeds, but some subsequent check in the vfs
   * may_open() fails, the struct *file gets cleaned up (i.e.
   * ceph_release gets called).  So fear not!
   */
  /*
   * flags
   *  path_lookup_open   -> LOOKUP_OPEN
   *  path_lookup_create -> LOOKUP_OPEN|LOOKUP_CREATE
   */
  struct dentry *ceph_lookup_open(struct inode *dir, struct dentry *dentry,
  				struct nameidata *nd, int mode,
  				int locked_dir)
  {

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

  	struct file *file;

  	struct ceph_mds_request *req;

  	struct dentry *ret;

  	int err;

  	int flags = nd->intent.open.flags;

  
  	dout("ceph_lookup_open dentry %p '%.*s' flags %d mode 0%o
  ",
  	     dentry, dentry->d_name.len, dentry->d_name.name, flags, mode);
  
  	/* do the open */
  	req = prepare_open_request(dir->i_sb, flags, mode);
  	if (IS_ERR(req))

  		return ERR_CAST(req);

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

  		err = ceph_handle_notrace_create(dir, dentry);

  	if (err)
  		goto out;
  	file = lookup_instantiate_filp(nd, req->r_dentry, ceph_open);
  	if (IS_ERR(file))
  		err = PTR_ERR(file);
  out:
  	ret = ceph_finish_lookup(req, dentry, err);

  	ceph_mdsc_put_request(req);

  	dout("ceph_lookup_open result=%p
  ", ret);
  	return ret;

  }
  
  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);
  	dput(cf->dentry);
  	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;
  }
  
  /*

   * 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, bool o_direct,

  			unsigned long buf_align)

  {

  	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);

  	struct ceph_inode_info *ci = ceph_inode(inode);
  	u64 pos, this_len;

  	int io_align, page_align;

  	int left, pages_left;
  	int read;
  	struct page **page_pos;
  	int ret;
  	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;

  	io_align = off & ~PAGE_MASK;

  
  more:

  	if (o_direct)

  		page_align = (pos - io_align + buf_align) & ~PAGE_MASK;

  	else
  		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~%u (read %u) got %d%s%s
  ", pos, left, read,
  	     ret, hit_stripe ? " HITSTRIPE" : "", was_short ? " SHORT" : "");
  
  	if (ret > 0) {

  		int didpages = (page_align + ret) >> PAGE_CACHE_SHIFT;

  
  		if (read < pos - off) {
  			dout(" zero gap %llu to %llu
  ", off + read, pos);

  			ceph_zero_page_vector_range(page_align + read,

  						    pos - off - read, pages);

  		}
  		pos += ret;
  		read = pos - off;
  		left -= ret;
  		page_pos += didpages;
  		pages_left -= didpages;
  
  		/* hit stripe? */
  		if (left && hit_stripe)
  			goto more;
  	}
  
  	if (was_short) {

  		/* did we bounce off eof? */
  		if (pos + left > inode->i_size)
  			*checkeof = 1;
  
  		/* zero trailing bytes (inside i_size) */
  		if (left > 0 && pos < inode->i_size) {
  			if (pos + left > inode->i_size)
  				left = inode->i_size - pos;
  
  			dout("zero tail %d
  ", left);

  			ceph_zero_page_vector_range(page_align + read, left,

  						    pages);

  			read += left;

  		}

  	}

  	if (ret >= 0)
  		ret = read;
  	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 file *file, char __user *data,

  			      unsigned len, loff_t *poff, int *checkeof)

  {
  	struct inode *inode = file->f_dentry->d_inode;
  	struct page **pages;
  	u64 off = *poff;

  	int num_pages, ret;

  
  	dout("sync_read on file %p %llu~%u %s
  ", file, off, len,
  	     (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");

  	if (file->f_flags & O_DIRECT) {
  		num_pages = calc_pages_for((unsigned long)data, len);

  		pages = ceph_get_direct_page_vector(data, num_pages, true);

  	} else {
  		num_pages = calc_pages_for(off, len);

  		pages = ceph_alloc_page_vector(num_pages, GFP_NOFS);

  	}

  	if (IS_ERR(pages))
  		return PTR_ERR(pages);

  	/*
  	 * 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(inode->i_mapping);
  	if (ret < 0)
  		goto done;

  	ret = striped_read(inode, off, len, pages, num_pages, checkeof,

  			   file->f_flags & O_DIRECT,
  			   (unsigned long)data & ~PAGE_MASK);

  
  	if (ret >= 0 && (file->f_flags & O_DIRECT) == 0)

  		ret = ceph_copy_page_vector_to_user(pages, data, off, ret);

  	if (ret >= 0)
  		*poff = off + ret;

  done:

  	if (file->f_flags & O_DIRECT)

  		ceph_put_page_vector(pages, num_pages, true);

  	else
  		ceph_release_page_vector(pages, num_pages);
  	dout("sync_read result %d
  ", ret);
  	return ret;
  }
  
  /*
   * Write commit callback, called if we requested both an ACK and
   * ONDISK commit reply from the OSD.
   */
  static void sync_write_commit(struct ceph_osd_request *req,
  			      struct ceph_msg *msg)
  {
  	struct ceph_inode_info *ci = ceph_inode(req->r_inode);
  
  	dout("sync_write_commit %p tid %llu
  ", req, req->r_tid);
  	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);
  }
  
  /*
   * Synchronous write, straight from __user pointer or user pages (if
   * O_DIRECT).
   *
   * 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 file *file, const char __user *data,
  			       size_t left, loff_t *offset)
  {
  	struct inode *inode = file->f_dentry->d_inode;
  	struct ceph_inode_info *ci = ceph_inode(inode);

  	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);

  	struct ceph_osd_request *req;
  	struct page **pages;
  	int num_pages;
  	long long unsigned pos;
  	u64 len;
  	int written = 0;
  	int flags;
  	int do_sync = 0;
  	int check_caps = 0;

  	int page_align, io_align;

  	unsigned long buf_align;

  	int ret;
  	struct timespec mtime = CURRENT_TIME;
  
  	if (ceph_snap(file->f_dentry->d_inode) != CEPH_NOSNAP)
  		return -EROFS;
  
  	dout("sync_write on file %p %lld~%u %s
  ", file, *offset,
  	     (unsigned)left, (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");
  
  	if (file->f_flags & O_APPEND)
  		pos = i_size_read(inode);
  	else
  		pos = *offset;

  	ret = filemap_write_and_wait_range(inode->i_mapping, pos, pos + left);
  	if (ret < 0)
  		return ret;
  
  	ret = invalidate_inode_pages2_range(inode->i_mapping,
  					    pos >> PAGE_CACHE_SHIFT,
  					    (pos + left) >> PAGE_CACHE_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;
  	if ((file->f_flags & (O_SYNC|O_DIRECT)) == 0)
  		flags |= CEPH_OSD_FLAG_ACK;
  	else
  		do_sync = 1;
  
  	/*
  	 * we may need to do multiple writes here if we span an object
  	 * boundary.  this isn't atomic, unfortunately.  :(
  	 */
  more:

  	io_align = pos & ~PAGE_MASK;
  	buf_align = (unsigned long)data & ~PAGE_MASK;

  	len = left;

  	if (file->f_flags & O_DIRECT) {

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

  		page_align = (pos - io_align + buf_align) & ~PAGE_MASK;
  		num_pages = calc_pages_for((unsigned long)data, len);
  	} else {

  		page_align = pos & ~PAGE_MASK;

  		num_pages = calc_pages_for(pos, len);
  	}

  	req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,

  				    ceph_vino(inode), pos, &len,
  				    CEPH_OSD_OP_WRITE, flags,
  				    ci->i_snap_realm->cached_context,
  				    do_sync,
  				    ci->i_truncate_seq, ci->i_truncate_size,

  				    &mtime, false, 2, page_align);

  	if (!req)
  		return -ENOMEM;

  	if (file->f_flags & O_DIRECT) {

  		pages = ceph_get_direct_page_vector(data, num_pages, false);

  		if (IS_ERR(pages)) {
  			ret = PTR_ERR(pages);
  			goto out;
  		}
  
  		/*
  		 * throw out any page cache pages in this range. this
  		 * may block.
  		 */

  		truncate_inode_pages_range(inode->i_mapping, pos,

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

  	} else {

  		pages = ceph_alloc_page_vector(num_pages, GFP_NOFS);

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

  		ret = ceph_copy_user_to_page_vector(pages, data, pos, len);

  		if (ret < 0) {
  			ceph_release_page_vector(pages, num_pages);
  			goto out;
  		}
  
  		if ((file->f_flags & O_SYNC) == 0) {
  			/* get a second commit callback */
  			req->r_safe_callback = sync_write_commit;
  			req->r_own_pages = 1;
  		}
  	}
  	req->r_pages = pages;
  	req->r_num_pages = num_pages;
  	req->r_inode = inode;

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

  	if (!ret) {
  		if (req->r_safe_callback) {
  			/*
  			 * Add to inode unsafe list only after we
  			 * start_request so that a tid has been assigned.
  			 */
  			spin_lock(&ci->i_unsafe_lock);

  			list_add_tail(&req->r_unsafe_item,
  				      &ci->i_unsafe_writes);

  			spin_unlock(&ci->i_unsafe_lock);
  			ceph_get_cap_refs(ci, CEPH_CAP_FILE_WR);
  		}

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

  		if (ret < 0 && req->r_safe_callback) {
  			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);
  		}

  	}
  
  	if (file->f_flags & O_DIRECT)

  		ceph_put_page_vector(pages, num_pages, false);

  	else if (file->f_flags & O_SYNC)
  		ceph_release_page_vector(pages, num_pages);
  
  out:
  	ceph_osdc_put_request(req);
  	if (ret == 0) {
  		pos += len;
  		written += len;
  		left -= len;

  		data += written;

  		if (left)
  			goto more;
  
  		ret = written;
  		*offset = pos;
  		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);
  	}
  	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_aio_read(struct kiocb *iocb, const struct iovec *iov,
  			     unsigned long nr_segs, loff_t pos)
  {
  	struct file *filp = iocb->ki_filp;

  	struct ceph_file_info *fi = filp->private_data;

  	loff_t *ppos = &iocb->ki_pos;
  	size_t len = iov->iov_len;
  	struct inode *inode = filp->f_dentry->d_inode;
  	struct ceph_inode_info *ci = ceph_inode(inode);

  	void __user *base = iov->iov_base;

  	ssize_t ret;

  	int want, got = 0;

  	int checkeof = 0, read = 0;

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

  again:

  	__ceph_do_pending_vmtruncate(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, &got, -1);

  	if (ret < 0)
  		goto out;
  	dout("aio_read %p %llx.%llx %llu~%u got cap refs on %s
  ",
  	     inode, ceph_vinop(inode), pos, (unsigned)len,
  	     ceph_cap_string(got));

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

  	    (iocb->ki_filp->f_flags & O_DIRECT) ||

  	    (inode->i_sb->s_flags & MS_SYNCHRONOUS) ||
  	    (fi->flags & CEPH_F_SYNC))

  		/* hmm, this isn't really async... */

  		ret = ceph_sync_read(filp, base, len, ppos, &checkeof);

  	else
  		ret = generic_file_aio_read(iocb, iov, nr_segs, pos);
  
  out:
  	dout("aio_read %p %llx.%llx dropping cap refs on %s = %d
  ",
  	     inode, ceph_vinop(inode), ceph_cap_string(got), (int)ret);
  	ceph_put_cap_refs(ci, got);

  
  	if (checkeof && ret >= 0) {
  		int statret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE);
  
  		/* hit EOF or hole? */
  		if (statret == 0 && *ppos < inode->i_size) {

  			dout("aio_read sync_read hit hole, ppos %lld < size %lld, reading more
  ", *ppos, inode->i_size);

  			read += ret;
  			base += ret;
  			len -= ret;
  			checkeof = 0;
  			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_aio_write(struct kiocb *iocb, const struct iovec *iov,
  		       unsigned long nr_segs, loff_t pos)
  {
  	struct file *file = iocb->ki_filp;

  	struct ceph_file_info *fi = file->private_data;

  	struct inode *inode = file->f_dentry->d_inode;
  	struct ceph_inode_info *ci = ceph_inode(inode);

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

  	loff_t endoff = pos + iov->iov_len;

  	int want, got = 0;

  	int ret, err;

  
  	if (ceph_snap(inode) != CEPH_NOSNAP)
  		return -EROFS;
  
  retry_snap:
  	if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL))
  		return -ENOSPC;
  	__ceph_do_pending_vmtruncate(inode);
  	dout("aio_write %p %llx.%llx %llu~%u getting caps. i_size %llu
  ",
  	     inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,
  	     inode->i_size);

  	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, &got, endoff);

  	if (ret < 0)

  		goto out_put;

  
  	dout("aio_write %p %llx.%llx %llu~%u  got cap refs on %s
  ",
  	     inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,
  	     ceph_cap_string(got));

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

  	    (iocb->ki_filp->f_flags & O_DIRECT) ||

  	    (inode->i_sb->s_flags & MS_SYNCHRONOUS) ||
  	    (fi->flags & CEPH_F_SYNC)) {

  		ret = ceph_sync_write(file, iov->iov_base, iov->iov_len,
  			&iocb->ki_pos);
  	} else {

  		/*
  		 * buffered write; drop Fw early to avoid slow
  		 * revocation if we get stuck on balance_dirty_pages
  		 */
  		int dirty;

  		spin_lock(&ci->i_ceph_lock);

  		dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR);

  		spin_unlock(&ci->i_ceph_lock);

  		ceph_put_cap_refs(ci, got);

  		ret = generic_file_aio_write(iocb, iov, nr_segs, pos);

  		if ((ret >= 0 || ret == -EIOCBQUEUED) &&
  		    ((file->f_flags & O_SYNC) || IS_SYNC(file->f_mapping->host)

  		     || ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_NEARFULL))) {

  			err = vfs_fsync_range(file, pos, pos + ret - 1, 1);

  			if (err < 0)
  				ret = err;
  		}

  
  		if (dirty)
  			__mark_inode_dirty(inode, dirty);
  		goto out;

  	}

  	if (ret >= 0) {

  		int dirty;

  		spin_lock(&ci->i_ceph_lock);

  		dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR);

  		spin_unlock(&ci->i_ceph_lock);

  		if (dirty)
  			__mark_inode_dirty(inode, dirty);

  	}

  out_put:

  	dout("aio_write %p %llx.%llx %llu~%u  dropping cap refs on %s
  ",
  	     inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,
  	     ceph_cap_string(got));
  	ceph_put_cap_refs(ci, got);

  out:

  	if (ret == -EOLDSNAPC) {
  		dout("aio_write %p %llx.%llx %llu~%u got EOLDSNAPC, retrying
  ",
  		     inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len);
  		goto retry_snap;
  	}
  
  	return ret;
  }
  
  /*
   * llseek.  be sure to verify file size on SEEK_END.
   */
  static loff_t ceph_llseek(struct file *file, loff_t offset, int origin)
  {
  	struct inode *inode = file->f_mapping->host;
  	int ret;
  
  	mutex_lock(&inode->i_mutex);
  	__ceph_do_pending_vmtruncate(inode);

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

  		ret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE);
  		if (ret < 0) {
  			offset = ret;
  			goto out;
  		}

  	}
  
  	switch (origin) {
  	case SEEK_END:

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

  	case SEEK_DATA:
  		if (offset >= inode->i_size) {
  			ret = -ENXIO;
  			goto out;
  		}
  		break;
  	case SEEK_HOLE:
  		if (offset >= inode->i_size) {
  			ret = -ENXIO;
  			goto out;
  		}
  		offset = inode->i_size;
  		break;

  	}
  
  	if (offset < 0 || offset > inode->i_sb->s_maxbytes) {
  		offset = -EINVAL;
  		goto out;
  	}
  
  	/* Special lock needed here? */
  	if (offset != file->f_pos) {
  		file->f_pos = offset;
  		file->f_version = 0;
  	}
  
  out:
  	mutex_unlock(&inode->i_mutex);
  	return offset;
  }
  
  const struct file_operations ceph_file_fops = {
  	.open = ceph_open,
  	.release = ceph_release,
  	.llseek = ceph_llseek,
  	.read = do_sync_read,
  	.write = do_sync_write,
  	.aio_read = ceph_aio_read,
  	.aio_write = ceph_aio_write,
  	.mmap = ceph_mmap,
  	.fsync = ceph_fsync,

  	.lock = ceph_lock,
  	.flock = ceph_flock,

  	.splice_read = generic_file_splice_read,
  	.splice_write = generic_file_splice_write,
  	.unlocked_ioctl = ceph_ioctl,
  	.compat_ioctl	= ceph_ioctl,
  };