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linux-next/fs/nfsd/filecache.h
Trond Myklebust 689827cd5b nfsd: convert file cache to use over/underflow safe refcount
Use the 'refcount_t' type instead of 'atomic_t' for improved
refcounting safety.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2020-02-06 11:22:55 -05:00

65 lines
2.4 KiB
C

#ifndef _FS_NFSD_FILECACHE_H
#define _FS_NFSD_FILECACHE_H
#include <linux/fsnotify_backend.h>
/*
* This is the fsnotify_mark container that nfsd attaches to the files that it
* is holding open. Note that we have a separate refcount here aside from the
* one in the fsnotify_mark. We only want a single fsnotify_mark attached to
* the inode, and for each nfsd_file to hold a reference to it.
*
* The fsnotify_mark is itself refcounted, but that's not sufficient to tell us
* how to put that reference. If there are still outstanding nfsd_files that
* reference the mark, then we would want to call fsnotify_put_mark on it.
* If there were not, then we'd need to call fsnotify_destroy_mark. Since we
* can't really tell the difference, we use the nfm_mark to keep track of how
* many nfsd_files hold references to the mark. When that counter goes to zero
* then we know to call fsnotify_destroy_mark on it.
*/
struct nfsd_file_mark {
struct fsnotify_mark nfm_mark;
refcount_t nfm_ref;
};
/*
* A representation of a file that has been opened by knfsd. These are hashed
* in the hashtable by inode pointer value. Note that this object doesn't
* hold a reference to the inode by itself, so the nf_inode pointer should
* never be dereferenced, only used for comparison.
*/
struct nfsd_file {
struct hlist_node nf_node;
struct list_head nf_lru;
struct rcu_head nf_rcu;
struct file *nf_file;
const struct cred *nf_cred;
struct net *nf_net;
#define NFSD_FILE_HASHED (0)
#define NFSD_FILE_PENDING (1)
#define NFSD_FILE_BREAK_READ (2)
#define NFSD_FILE_BREAK_WRITE (3)
#define NFSD_FILE_REFERENCED (4)
unsigned long nf_flags;
struct inode *nf_inode;
unsigned int nf_hashval;
refcount_t nf_ref;
unsigned char nf_may;
struct nfsd_file_mark *nf_mark;
struct rw_semaphore nf_rwsem;
};
int nfsd_file_cache_init(void);
void nfsd_file_cache_purge(struct net *);
void nfsd_file_cache_shutdown(void);
int nfsd_file_cache_start_net(struct net *net);
void nfsd_file_cache_shutdown_net(struct net *net);
void nfsd_file_put(struct nfsd_file *nf);
struct nfsd_file *nfsd_file_get(struct nfsd_file *nf);
void nfsd_file_close_inode_sync(struct inode *inode);
bool nfsd_file_is_cached(struct inode *inode);
__be32 nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
unsigned int may_flags, struct nfsd_file **nfp);
int nfsd_file_cache_stats_open(struct inode *, struct file *);
#endif /* _FS_NFSD_FILECACHE_H */