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There have been reports of races that cause NFSv4 OPEN(CREATE) to return an error even though the requested file was created. NFSv4 does not provide a status code for this case. To mitigate some of these problems, reorganize the NFSv4 OPEN(CREATE) logic to allocate resources before the file is actually created, and open the new file while the parent directory is still locked. Two new APIs are added: + Add an API that works like nfsd_file_acquire() but does not open the underlying file. The OPEN(CREATE) path can use this API when it already has an open file. + Add an API that is kin to dentry_open(). NFSD needs to create a file and grab an open "struct file *" atomically. The alloc_empty_file() has to be done before the inode create. If it fails (for example, because the NFS server has exceeded its max_files limit), we avoid creating the file and can still return an error to the NFS client. BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=382 Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Tested-by: JianHong Yin <jiyin@redhat.com>
65 lines
2.5 KiB
C
65 lines
2.5 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 hlist_node nf_node;
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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_BREAK_READ (2)
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#define NFSD_FILE_BREAK_WRITE (3)
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#define NFSD_FILE_REFERENCED (4)
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unsigned long nf_flags;
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struct inode *nf_inode;
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unsigned int nf_hashval;
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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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};
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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(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_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
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unsigned int may_flags, struct nfsd_file **nfp);
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int nfsd_file_cache_stats_open(struct inode *, struct file *);
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#endif /* _FS_NFSD_FILECACHE_H */
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