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c25a89770d
Instead of calling xchg() and unrcu_pointer() before
nfsd_file_put_local(), we now pass pointer to the __rcu pointer and call
xchg() and unrcu_pointer() inside that function.
Where unrcu_pointer() is currently called the internals of "struct
nfsd_file" are not known and that causes older compilers such as gcc-8
to complain.
In some cases we have a __kernel (aka normal) pointer not an __rcu
pointer so we need to cast it to __rcu first. This is strictly a
weakening so no information is lost. Somewhat surprisingly, this cast
is accepted by gcc-8.
This has the pleasing result that the cmpxchg() which sets ro_file and
rw_file, and also the xchg() which clears them, are both now in the nfsd
code.
Reported-by: Pali Rohár <pali@kernel.org>
Reported-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Fixes: 86e0041225 ("nfs: cache all open LOCALIO nfsd_file(s) in client")
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
83 lines
3.2 KiB
C
83 lines
3.2 KiB
C
#ifndef _FS_NFSD_FILECACHE_H
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#define _FS_NFSD_FILECACHE_H
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#include <linux/fsnotify_backend.h>
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/*
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* Limit the time that the list_lru_one lock is held during
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* an LRU scan.
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*/
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#define NFSD_FILE_GC_BATCH (16UL)
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/*
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* This is the fsnotify_mark container that nfsd attaches to the files that it
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* is holding open. Note that we have a separate refcount here aside from the
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* one in the fsnotify_mark. We only want a single fsnotify_mark attached to
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* the inode, and for each nfsd_file to hold a reference to it.
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*
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* The fsnotify_mark is itself refcounted, but that's not sufficient to tell us
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* how to put that reference. If there are still outstanding nfsd_files that
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* reference the mark, then we would want to call fsnotify_put_mark on it.
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* If there were not, then we'd need to call fsnotify_destroy_mark. Since we
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* can't really tell the difference, we use the nfm_mark to keep track of how
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* many nfsd_files hold references to the mark. When that counter goes to zero
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* then we know to call fsnotify_destroy_mark on it.
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*/
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struct nfsd_file_mark {
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struct fsnotify_mark nfm_mark;
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refcount_t nfm_ref;
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};
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/*
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* A representation of a file that has been opened by knfsd. These are hashed
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* in the hashtable by inode pointer value. Note that this object doesn't
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* hold a reference to the inode by itself, so the nf_inode pointer should
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* never be dereferenced, only used for comparison.
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*/
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struct nfsd_file {
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struct rhlist_head nf_rlist;
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void *nf_inode;
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struct file *nf_file;
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const struct cred *nf_cred;
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struct net *nf_net;
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#define NFSD_FILE_HASHED (0)
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#define NFSD_FILE_PENDING (1)
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#define NFSD_FILE_REFERENCED (2)
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#define NFSD_FILE_GC (3)
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#define NFSD_FILE_RECENT (4)
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unsigned long nf_flags;
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refcount_t nf_ref;
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unsigned char nf_may;
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struct nfsd_file_mark *nf_mark;
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struct list_head nf_lru;
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struct list_head nf_gc;
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struct rcu_head nf_rcu;
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ktime_t nf_birthtime;
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};
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int nfsd_file_cache_init(void);
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void nfsd_file_cache_purge(struct net *);
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void nfsd_file_cache_shutdown(void);
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int nfsd_file_cache_start_net(struct net *net);
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void nfsd_file_cache_shutdown_net(struct net *net);
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void nfsd_file_put(struct nfsd_file *nf);
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struct net *nfsd_file_put_local(struct nfsd_file __rcu **nf);
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struct nfsd_file *nfsd_file_get_local(struct nfsd_file *nf);
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struct nfsd_file *nfsd_file_get(struct nfsd_file *nf);
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struct file *nfsd_file_file(struct nfsd_file *nf);
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void nfsd_file_close_inode_sync(struct inode *inode);
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void nfsd_file_net_dispose(struct nfsd_net *nn);
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bool nfsd_file_is_cached(struct inode *inode);
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__be32 nfsd_file_acquire_gc(struct svc_rqst *rqstp, struct svc_fh *fhp,
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unsigned int may_flags, struct nfsd_file **nfp);
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__be32 nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
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unsigned int may_flags, struct nfsd_file **nfp);
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__be32 nfsd_file_acquire_opened(struct svc_rqst *rqstp, struct svc_fh *fhp,
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unsigned int may_flags, struct file *file,
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struct nfsd_file **nfp);
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__be32 nfsd_file_acquire_local(struct net *net, struct svc_cred *cred,
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struct auth_domain *client, struct svc_fh *fhp,
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unsigned int may_flags, struct nfsd_file **pnf);
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int nfsd_file_cache_stats_show(struct seq_file *m, void *v);
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#endif /* _FS_NFSD_FILECACHE_H */
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