402cb8dda9
Attach copies of the index key and auxiliary data to the fscache cookie so
that:
(1) The callbacks to the netfs for this stuff can be eliminated. This
can simplify things in the cache as the information is still
available, even after the cache has relinquished the cookie.
(2) Simplifies the locking requirements of accessing the information as we
don't have to worry about the netfs object going away on us.
(3) The cache can do lazy updating of the coherency information on disk.
As long as the cache is flushed before reboot/poweroff, there's no
need to update the coherency info on disk every time it changes.
(4) Cookies can be hashed or put in a tree as the index key is easily
available. This allows:
(a) Checks for duplicate cookies can be made at the top fscache layer
rather than down in the bowels of the cache backend.
(b) Caching can be added to a netfs object that has a cookie if the
cache is brought online after the netfs object is allocated.
A certain amount of space is made in the cookie for inline copies of the
data, but if it won't fit there, extra memory will be allocated for it.
The downside of this is that live cache operation requires more memory.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Anna Schumaker <anna.schumaker@netapp.com>
Tested-by: Steve Dickson <steved@redhat.com>
151 lines
3.8 KiB
C
151 lines
3.8 KiB
C
/*
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* fs/cifs/cache.c - CIFS filesystem cache index structure definitions
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*
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* Copyright (c) 2010 Novell, Inc.
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* Authors(s): Suresh Jayaraman (sjayaraman@suse.de>
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published
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* by the Free Software Foundation; either version 2.1 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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* the GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "fscache.h"
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#include "cifs_debug.h"
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/*
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* CIFS filesystem definition for FS-Cache
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*/
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struct fscache_netfs cifs_fscache_netfs = {
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.name = "cifs",
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.version = 0,
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};
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/*
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* Register CIFS for caching with FS-Cache
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*/
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int cifs_fscache_register(void)
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{
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return fscache_register_netfs(&cifs_fscache_netfs);
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}
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/*
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* Unregister CIFS for caching
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*/
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void cifs_fscache_unregister(void)
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{
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fscache_unregister_netfs(&cifs_fscache_netfs);
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}
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/*
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* Server object for FS-Cache
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*/
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const struct fscache_cookie_def cifs_fscache_server_index_def = {
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.name = "CIFS.server",
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.type = FSCACHE_COOKIE_TYPE_INDEX,
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};
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/*
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* Auxiliary data attached to CIFS superblock within the cache
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*/
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struct cifs_fscache_super_auxdata {
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u64 resource_id; /* unique server resource id */
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};
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char *extract_sharename(const char *treename)
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{
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const char *src;
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char *delim, *dst;
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int len;
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/* skip double chars at the beginning */
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src = treename + 2;
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/* share name is always preceded by '\\' now */
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delim = strchr(src, '\\');
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if (!delim)
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return ERR_PTR(-EINVAL);
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delim++;
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len = strlen(delim);
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/* caller has to free the memory */
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dst = kstrndup(delim, len, GFP_KERNEL);
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if (!dst)
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return ERR_PTR(-ENOMEM);
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return dst;
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}
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static enum
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fscache_checkaux cifs_fscache_super_check_aux(void *cookie_netfs_data,
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const void *data,
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uint16_t datalen)
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{
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struct cifs_fscache_super_auxdata auxdata;
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const struct cifs_tcon *tcon = cookie_netfs_data;
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if (datalen != sizeof(auxdata))
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return FSCACHE_CHECKAUX_OBSOLETE;
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memset(&auxdata, 0, sizeof(auxdata));
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auxdata.resource_id = tcon->resource_id;
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if (memcmp(data, &auxdata, datalen) != 0)
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return FSCACHE_CHECKAUX_OBSOLETE;
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return FSCACHE_CHECKAUX_OKAY;
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}
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/*
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* Superblock object for FS-Cache
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*/
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const struct fscache_cookie_def cifs_fscache_super_index_def = {
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.name = "CIFS.super",
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.type = FSCACHE_COOKIE_TYPE_INDEX,
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.check_aux = cifs_fscache_super_check_aux,
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};
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static void
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cifs_fscache_inode_get_attr(const void *cookie_netfs_data, uint64_t *size)
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{
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const struct cifsInodeInfo *cifsi = cookie_netfs_data;
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*size = cifsi->vfs_inode.i_size;
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}
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static enum
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fscache_checkaux cifs_fscache_inode_check_aux(void *cookie_netfs_data,
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const void *data,
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uint16_t datalen)
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{
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struct cifs_fscache_inode_auxdata auxdata;
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struct cifsInodeInfo *cifsi = cookie_netfs_data;
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if (datalen != sizeof(auxdata))
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return FSCACHE_CHECKAUX_OBSOLETE;
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memset(&auxdata, 0, sizeof(auxdata));
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auxdata.eof = cifsi->server_eof;
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auxdata.last_write_time = cifsi->vfs_inode.i_mtime;
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auxdata.last_change_time = cifsi->vfs_inode.i_ctime;
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if (memcmp(data, &auxdata, datalen) != 0)
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return FSCACHE_CHECKAUX_OBSOLETE;
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return FSCACHE_CHECKAUX_OKAY;
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}
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const struct fscache_cookie_def cifs_fscache_inode_object_def = {
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.name = "CIFS.uniqueid",
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.type = FSCACHE_COOKIE_TYPE_DATAFILE,
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.get_attr = cifs_fscache_inode_get_attr,
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.check_aux = cifs_fscache_inode_check_aux,
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};
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