/*
   *   fs/cifs/fscache.c - CIFS filesystem cache interface
   *
   *   Copyright (c) 2010 Novell, Inc.
   *   Author(s): Suresh Jayaraman <sjayaraman@suse.de>
   *
   *   This library is free software; you can redistribute it and/or modify
   *   it under the terms of the GNU Lesser General Public License as published
   *   by the Free Software Foundation; either version 2.1 of the License, or
   *   (at your option) any later version.
   *
   *   This library is distributed in the hope that it will be useful,
   *   but WITHOUT ANY WARRANTY; without even the implied warranty of
   *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
   *   the GNU Lesser General Public License for more details.
   *
   *   You should have received a copy of the GNU Lesser General Public License
   *   along with this library; if not, write to the Free Software
   *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
   */
  #include "fscache.h"
  #include "cifsglob.h"
  #include "cifs_debug.h"
  #include "cifs_fs_sb.h"
  
  void cifs_fscache_get_client_cookie(struct TCP_Server_Info *server)
  {
  	server->fscache =
  		fscache_acquire_cookie(cifs_fscache_netfs.primary_index,
  				&cifs_fscache_server_index_def, server, true);
  	cifs_dbg(FYI, "%s: (0x%p/0x%p)
  ",
  		 __func__, server, server->fscache);
  }
  
  void cifs_fscache_release_client_cookie(struct TCP_Server_Info *server)
  {
  	cifs_dbg(FYI, "%s: (0x%p/0x%p)
  ",
  		 __func__, server, server->fscache);
  	fscache_relinquish_cookie(server->fscache, 0);
  	server->fscache = NULL;
  }
  
  void cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
  {
  	struct TCP_Server_Info *server = tcon->ses->server;
  
  	tcon->fscache =
  		fscache_acquire_cookie(server->fscache,
  				&cifs_fscache_super_index_def, tcon, true);
  	cifs_dbg(FYI, "%s: (0x%p/0x%p)
  ",
  		 __func__, server->fscache, tcon->fscache);
  }
  
  void cifs_fscache_release_super_cookie(struct cifs_tcon *tcon)
  {
  	cifs_dbg(FYI, "%s: (0x%p)
  ", __func__, tcon->fscache);
  	fscache_relinquish_cookie(tcon->fscache, 0);
  	tcon->fscache = NULL;
  }
  
  static void cifs_fscache_enable_inode_cookie(struct inode *inode)
  {
  	struct cifsInodeInfo *cifsi = CIFS_I(inode);
  	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
  	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
  
  	if (cifsi->fscache)
  		return;
  
  	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_FSCACHE) {
  		cifsi->fscache = fscache_acquire_cookie(tcon->fscache,
  				&cifs_fscache_inode_object_def, cifsi, true);
  		cifs_dbg(FYI, "%s: got FH cookie (0x%p/0x%p)
  ",
  			 __func__, tcon->fscache, cifsi->fscache);
  	}
  }
  
  void cifs_fscache_release_inode_cookie(struct inode *inode)
  {
  	struct cifsInodeInfo *cifsi = CIFS_I(inode);
  
  	if (cifsi->fscache) {
  		cifs_dbg(FYI, "%s: (0x%p)
  ", __func__, cifsi->fscache);
  		fscache_relinquish_cookie(cifsi->fscache, 0);
  		cifsi->fscache = NULL;
  	}
  }
  
  static void cifs_fscache_disable_inode_cookie(struct inode *inode)
  {
  	struct cifsInodeInfo *cifsi = CIFS_I(inode);
  
  	if (cifsi->fscache) {
  		cifs_dbg(FYI, "%s: (0x%p)
  ", __func__, cifsi->fscache);
  		fscache_uncache_all_inode_pages(cifsi->fscache, inode);
  		fscache_relinquish_cookie(cifsi->fscache, 1);
  		cifsi->fscache = NULL;
  	}
  }
  
  void cifs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
  {
  	if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
  		cifs_fscache_disable_inode_cookie(inode);
  	else
  		cifs_fscache_enable_inode_cookie(inode);
  }
  
  void cifs_fscache_reset_inode_cookie(struct inode *inode)
  {
  	struct cifsInodeInfo *cifsi = CIFS_I(inode);
  	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
  	struct fscache_cookie *old = cifsi->fscache;
  
  	if (cifsi->fscache) {
  		/* retire the current fscache cache and get a new one */
  		fscache_relinquish_cookie(cifsi->fscache, 1);
  
  		cifsi->fscache = fscache_acquire_cookie(
  					cifs_sb_master_tcon(cifs_sb)->fscache,
  					&cifs_fscache_inode_object_def,
  					cifsi, true);
  		cifs_dbg(FYI, "%s: new cookie 0x%p oldcookie 0x%p
  ",
  			 __func__, cifsi->fscache, old);
  	}
  }
  
  int cifs_fscache_release_page(struct page *page, gfp_t gfp)
  {
  	if (PageFsCache(page)) {
  		struct inode *inode = page->mapping->host;
  		struct cifsInodeInfo *cifsi = CIFS_I(inode);
  
  		cifs_dbg(FYI, "%s: (0x%p/0x%p)
  ",
  			 __func__, page, cifsi->fscache);
  		if (!fscache_maybe_release_page(cifsi->fscache, page, gfp))
  			return 0;
  	}
  
  	return 1;
  }
  
  static void cifs_readpage_from_fscache_complete(struct page *page, void *ctx,
  						int error)
  {
  	cifs_dbg(FYI, "%s: (0x%p/%d)
  ", __func__, page, error);
  	if (!error)
  		SetPageUptodate(page);
  	unlock_page(page);
  }
  
  /*
   * Retrieve a page from FS-Cache
   */
  int __cifs_readpage_from_fscache(struct inode *inode, struct page *page)
  {
  	int ret;
  
  	cifs_dbg(FYI, "%s: (fsc:%p, p:%p, i:0x%p
  ",
  		 __func__, CIFS_I(inode)->fscache, page, inode);
  	ret = fscache_read_or_alloc_page(CIFS_I(inode)->fscache, page,
  					 cifs_readpage_from_fscache_complete,
  					 NULL,
  					 GFP_KERNEL);
  	switch (ret) {
  
  	case 0: /* page found in fscache, read submitted */
  		cifs_dbg(FYI, "%s: submitted
  ", __func__);
  		return ret;
  	case -ENOBUFS:	/* page won't be cached */
  	case -ENODATA:	/* page not in cache */
  		cifs_dbg(FYI, "%s: %d
  ", __func__, ret);
  		return 1;
  
  	default:
  		cifs_dbg(VFS, "unknown error ret = %d
  ", ret);
  	}
  	return ret;
  }
  
  /*
   * Retrieve a set of pages from FS-Cache
   */
  int __cifs_readpages_from_fscache(struct inode *inode,
  				struct address_space *mapping,
  				struct list_head *pages,
  				unsigned *nr_pages)
  {
  	int ret;
  
  	cifs_dbg(FYI, "%s: (0x%p/%u/0x%p)
  ",
  		 __func__, CIFS_I(inode)->fscache, *nr_pages, inode);
  	ret = fscache_read_or_alloc_pages(CIFS_I(inode)->fscache, mapping,
  					  pages, nr_pages,
  					  cifs_readpage_from_fscache_complete,
  					  NULL,
  					  mapping_gfp_mask(mapping));
  	switch (ret) {
  	case 0:	/* read submitted to the cache for all pages */
  		cifs_dbg(FYI, "%s: submitted
  ", __func__);
  		return ret;
  
  	case -ENOBUFS:	/* some pages are not cached and can't be */
  	case -ENODATA:	/* some pages are not cached */
  		cifs_dbg(FYI, "%s: no page
  ", __func__);
  		return 1;
  
  	default:
  		cifs_dbg(FYI, "unknown error ret = %d
  ", ret);
  	}
  
  	return ret;
  }
  
  void __cifs_readpage_to_fscache(struct inode *inode, struct page *page)
  {
  	int ret;
  
  	cifs_dbg(FYI, "%s: (fsc: %p, p: %p, i: %p)
  ",
  		 __func__, CIFS_I(inode)->fscache, page, inode);
  	ret = fscache_write_page(CIFS_I(inode)->fscache, page, GFP_KERNEL);
  	if (ret != 0)
  		fscache_uncache_page(CIFS_I(inode)->fscache, page);
  }
  
  void __cifs_fscache_readpages_cancel(struct inode *inode, struct list_head *pages)
  {
  	cifs_dbg(FYI, "%s: (fsc: %p, i: %p)
  ",
  		 __func__, CIFS_I(inode)->fscache, inode);
  	fscache_readpages_cancel(CIFS_I(inode)->fscache, pages);
  }
  
  void __cifs_fscache_invalidate_page(struct page *page, struct inode *inode)
  {
  	struct cifsInodeInfo *cifsi = CIFS_I(inode);
  	struct fscache_cookie *cookie = cifsi->fscache;
  
  	cifs_dbg(FYI, "%s: (0x%p/0x%p)
  ", __func__, page, cookie);
  	fscache_wait_on_page_write(cookie, page);
  	fscache_uncache_page(cookie, page);
  }