Store a hint in the nfsnode to detect sequential access of the file.
Kick off a readahead only when sequential access is detected. This eliminates wasteful readaheads in random file access. Submitted by: Mohan Srinivasan mohans at yahoo-inc dot com Obtained from: Yahoo!
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02a85ee096
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4342aac774
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=138644
@ -421,8 +421,10 @@ nfs_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred)
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/*
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* Start the read ahead(s), as required.
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* The readahead is kicked off only if sequential access
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* is detected, based on the readahead hint (ra_expect_lbn).
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*/
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if (nmp->nm_readahead > 0) {
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if (nmp->nm_readahead > 0 && np->ra_expect_lbn == lbn) {
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for (nra = 0; nra < nmp->nm_readahead && nra < seqcount &&
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(off_t)(lbn + 1 + nra) * biosize < np->n_size; nra++) {
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rabn = lbn + 1 + nra;
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@ -448,6 +450,7 @@ nfs_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred)
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}
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}
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}
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np->ra_expect_lbn = lbn + 1;
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}
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/*
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@ -434,6 +434,7 @@ nfs_open(struct vop_open_args *ap)
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np->n_mtime = vattr.va_mtime;
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}
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}
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np->ra_expect_lbn = 0;
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return (0);
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}
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@ -126,6 +126,7 @@ struct nfsnode {
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struct nfs4_fctx n_wfc;
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u_char *n_name; /* leaf name, for v4 OPEN op */
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uint32_t n_namelen;
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daddr_t ra_expect_lbn;
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};
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#define n_atim n_un1.nf_atim
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