fscache.c

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/*
 *   fs/cifs/fscache.c - CIFS filesystem cache interface
 *
 *   Copyright (c) 2010 Novell, Inc.
 *   Author(s): Suresh Jayaraman <[email protected]>
 *
 *   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);
    cFYI(1, "%s: (0x%p/0x%p)", __func__, server,
            server->fscache);
}

void cifs_fscache_release_client_cookie(struct TCP_Server_Info *server)
{
    cFYI(1, "%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);
    cFYI(1, "%s: (0x%p/0x%p)", __func__, server->fscache,
            tcon->fscache);
}

void cifs_fscache_release_super_cookie(struct cifs_tcon *tcon)
{
    cFYI(1, "%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);
        cFYI(1, "%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) {
        cFYI(1, "%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) {
        cFYI(1, "%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);
        cFYI(1, "%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);

        cFYI(1, "%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)
{
    cFYI(1, "%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;

    cFYI(1, "%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 */
        cFYI(1, "%s: submitted", __func__);
        return ret;
    case -ENOBUFS:  /* page won't be cached */
    case -ENODATA:  /* page not in cache */
        cFYI(1, "%s: %d", __func__, ret);
        return 1;

    default:
        cERROR(1, "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;

    cFYI(1, "%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 */
        cFYI(1, "%s: submitted", __func__);
        return ret;

    case -ENOBUFS:  /* some pages are not cached and can't be */
    case -ENODATA:  /* some pages are not cached */
        cFYI(1, "%s: no page", __func__);
        return 1;

    default:
        cFYI(1, "unknown error ret = %d", ret);
    }

    return ret;
}

void __cifs_readpage_to_fscache(struct inode *inode, struct page *page)
{
    int ret;

    cFYI(1, "%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_invalidate_page(struct page *page, struct inode *inode)
{
    struct cifsInodeInfo *cifsi = CIFS_I(inode);
    struct fscache_cookie *cookie = cifsi->fscache;

    cFYI(1, "%s: (0x%p/0x%p)", __func__, page, cookie);
    fscache_wait_on_page_write(cookie, page);
    fscache_uncache_page(cookie, page);
}