/*
 *   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)\n",
                 __func__, server, server->fscache);
}

void cifs_fscache_release_client_cookie(struct TCP_Server_Info *server)
{
        cifs_dbg(FYI, "%s: (0x%p/0x%p)\n",
                 __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)\n",
                 __func__, server->fscache, tcon->fscache);
}

void cifs_fscache_release_super_cookie(struct cifs_tcon *tcon)
{
        cifs_dbg(FYI, "%s: (0x%p)\n", __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)\n",
                         __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)\n", __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)\n", __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\n",
                         __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)\n",
                         __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)\n", __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\n",
                 __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\n", __func__);
                return ret;
        case -ENOBUFS:  /* page won't be cached */
        case -ENODATA:  /* page not in cache */
                cifs_dbg(FYI, "%s: %d\n", __func__, ret);
                return 1;

        default:
                cifs_dbg(VFS, "unknown error ret = %d\n", 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)\n",
                 __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\n", __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\n", __func__);
                return 1;

        default:
                cifs_dbg(FYI, "unknown error ret = %d\n", 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)\n",
                 __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)\n",
                 __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)\n", __func__, page, cookie);
        fscache_wait_on_page_write(cookie, page);
        fscache_uncache_page(cookie, page);
}