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Commitfb70bf124b("NFSD: Instantiate a struct file when creating a regular NFSv4 file") added the ability to cache an open fd over a compound. There are a couple of problems with the way this currently works: It's racy, as a newly-created nfsd_file can end up with its PENDING bit cleared while the nf is hashed, and the nf_file pointer is still zeroed out. Other tasks can find it in this state and they expect to see a valid nf_file, and can oops if nf_file is NULL. Also, there is no guarantee that we'll end up creating a new nfsd_file if one is already in the hash. If an extant entry is in the hash with a valid nf_file, nfs4_get_vfs_file will clobber its nf_file pointer with the value of op_file and the old nf_file will leak. Fix both issues by making a new nfsd_file_acquirei_opened variant that takes an optional file pointer. If one is present when this is called, we'll take a new reference to it instead of trying to open the file. If the nfsd_file already has a valid nf_file, we'll just ignore the optional file and pass the nfsd_file back as-is. Also rework the tracepoints a bit to allow for an "opened" variant and don't try to avoid counting acquisitions in the case where we already have a cached open file. Fixes:fb70bf124b("NFSD: Instantiate a struct file when creating a regular NFSv4 file") Cc: Trond Myklebust <trondmy@hammerspace.com> Reported-by: Stanislav Saner <ssaner@redhat.com> Reported-and-Tested-by: Ruben Vestergaard <rubenv@drcmr.dk> Reported-and-Tested-by: Torkil Svensgaard <torkil@drcmr.dk> Signed-off-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
68 lines
2.6 KiB
C
68 lines
2.6 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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* 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 rhash_head nf_rhash;
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struct list_head nf_lru;
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struct rcu_head nf_rcu;
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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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unsigned long nf_flags;
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struct inode *nf_inode; /* don't deref */
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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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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 nfsd_file *nfsd_file_get(struct nfsd_file *nf);
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void nfsd_file_close_inode_sync(struct inode *inode);
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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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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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