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NFSD: Document lack of f_pos_lock in nfsd_readdir()
Al Viro notes that normal system calls hold f_pos_lock when calling ->iterate_shared and ->llseek; however nfsd_readdir() does not take that mutex when calling these methods. It should be safe however because the struct file acquired by nfsd_readdir() is not visible to other threads. Reviewed-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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@ -2102,9 +2102,23 @@ static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
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return cdp->err;
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}
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/*
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* Read entries from a directory.
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* The NFSv3/4 verifier we ignore for now.
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/**
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* nfsd_readdir - Read entries from a directory
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* @rqstp: RPC transaction context
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* @fhp: NFS file handle of directory to be read
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* @offsetp: OUT: seek offset of final entry that was read
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* @cdp: OUT: an eof error value
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* @func: entry filler actor
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*
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* This implementation ignores the NFSv3/4 verifier cookie.
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*
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* NB: normal system calls hold file->f_pos_lock when calling
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* ->iterate_shared and ->llseek, but nfsd_readdir() does not.
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* Because the struct file acquired here is not visible to other
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* threads, it's internal state does not need mutex protection.
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*
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* Returns nfs_ok on success, otherwise an nfsstat code is
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* returned.
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*/
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__be32
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nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp,
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