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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>
163 lines
5.1 KiB
C
163 lines
5.1 KiB
C
/*
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* fs/cifs/fscache.h - CIFS filesystem cache interface 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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#ifndef _CIFS_FSCACHE_H
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#define _CIFS_FSCACHE_H
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#include <linux/fscache.h>
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#include "cifsglob.h"
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#ifdef CONFIG_CIFS_FSCACHE
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/*
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* Auxiliary data attached to CIFS inode within the cache
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*/
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struct cifs_fscache_inode_auxdata {
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struct timespec last_write_time;
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struct timespec last_change_time;
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u64 eof;
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};
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/*
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* cache.c
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*/
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extern struct fscache_netfs cifs_fscache_netfs;
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extern const struct fscache_cookie_def cifs_fscache_server_index_def;
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extern const struct fscache_cookie_def cifs_fscache_super_index_def;
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extern const struct fscache_cookie_def cifs_fscache_inode_object_def;
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extern int cifs_fscache_register(void);
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extern void cifs_fscache_unregister(void);
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extern char *extract_sharename(const char *);
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/*
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* fscache.c
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*/
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extern void cifs_fscache_get_client_cookie(struct TCP_Server_Info *);
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extern void cifs_fscache_release_client_cookie(struct TCP_Server_Info *);
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extern void cifs_fscache_get_super_cookie(struct cifs_tcon *);
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extern void cifs_fscache_release_super_cookie(struct cifs_tcon *);
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extern void cifs_fscache_release_inode_cookie(struct inode *);
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extern void cifs_fscache_set_inode_cookie(struct inode *, struct file *);
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extern void cifs_fscache_reset_inode_cookie(struct inode *);
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extern void __cifs_fscache_invalidate_page(struct page *, struct inode *);
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extern int cifs_fscache_release_page(struct page *page, gfp_t gfp);
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extern int __cifs_readpage_from_fscache(struct inode *, struct page *);
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extern int __cifs_readpages_from_fscache(struct inode *,
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struct address_space *,
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struct list_head *,
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unsigned *);
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extern void __cifs_fscache_readpages_cancel(struct inode *, struct list_head *);
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extern void __cifs_readpage_to_fscache(struct inode *, struct page *);
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static inline void cifs_fscache_invalidate_page(struct page *page,
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struct inode *inode)
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{
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if (PageFsCache(page))
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__cifs_fscache_invalidate_page(page, inode);
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}
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static inline int cifs_readpage_from_fscache(struct inode *inode,
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struct page *page)
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{
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if (CIFS_I(inode)->fscache)
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return __cifs_readpage_from_fscache(inode, page);
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return -ENOBUFS;
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}
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static inline int cifs_readpages_from_fscache(struct inode *inode,
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struct address_space *mapping,
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struct list_head *pages,
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unsigned *nr_pages)
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{
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if (CIFS_I(inode)->fscache)
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return __cifs_readpages_from_fscache(inode, mapping, pages,
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nr_pages);
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return -ENOBUFS;
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}
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static inline void cifs_readpage_to_fscache(struct inode *inode,
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struct page *page)
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{
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if (PageFsCache(page))
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__cifs_readpage_to_fscache(inode, page);
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}
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static inline void cifs_fscache_readpages_cancel(struct inode *inode,
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struct list_head *pages)
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{
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if (CIFS_I(inode)->fscache)
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return __cifs_fscache_readpages_cancel(inode, pages);
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}
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#else /* CONFIG_CIFS_FSCACHE */
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static inline int cifs_fscache_register(void) { return 0; }
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static inline void cifs_fscache_unregister(void) {}
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static inline void
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cifs_fscache_get_client_cookie(struct TCP_Server_Info *server) {}
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static inline void
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cifs_fscache_release_client_cookie(struct TCP_Server_Info *server) {}
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static inline void cifs_fscache_get_super_cookie(struct cifs_tcon *tcon) {}
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static inline void
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cifs_fscache_release_super_cookie(struct cifs_tcon *tcon) {}
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static inline void cifs_fscache_release_inode_cookie(struct inode *inode) {}
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static inline void cifs_fscache_set_inode_cookie(struct inode *inode,
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struct file *filp) {}
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static inline void cifs_fscache_reset_inode_cookie(struct inode *inode) {}
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static inline int cifs_fscache_release_page(struct page *page, gfp_t gfp)
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{
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return 1; /* May release page */
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}
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static inline void cifs_fscache_invalidate_page(struct page *page,
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struct inode *inode) {}
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static inline int
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cifs_readpage_from_fscache(struct inode *inode, struct page *page)
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{
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return -ENOBUFS;
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}
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static inline int cifs_readpages_from_fscache(struct inode *inode,
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struct address_space *mapping,
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struct list_head *pages,
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unsigned *nr_pages)
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{
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return -ENOBUFS;
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}
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static inline void cifs_readpage_to_fscache(struct inode *inode,
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struct page *page) {}
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static inline void cifs_fscache_readpages_cancel(struct inode *inode,
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struct list_head *pages)
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{
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}
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#endif /* CONFIG_CIFS_FSCACHE */
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#endif /* _CIFS_FSCACHE_H */
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