From eab7e2e647c348b418e8715ecaca0177e1b473c7 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 27 Mar 2006 01:15:00 -0800 Subject: [PATCH] [PATCH] knfsd: Break the hard linkage from svc_expkey to svc_export Current svc_expkey holds a pointer to the svc_export structure, so updates to that structure have to be in-place, which is a wart on the whole cache infrastruct. So we break that linkage and just do a second lookup. If this became a performance issue, it would be possible to put a direct link back in which was only used conditionally. i.e. when an object is replaced in the cache, we set a flag in the old object. When dereferencing the link from svc_expkey, if the flag is set, we drop the reference and do a fresh lookup. Signed-off-by: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/nfsd/export.c | 60 ++++++++++++++++++++++++++++++--------------- include/linux/nfsd/export.h | 20 +++------------ 2 files changed, 44 insertions(+), 36 deletions(-) diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index ac09977..587829e 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -73,8 +73,10 @@ void expkey_put(struct cache_head *item, struct cache_detail *cd) if (cache_put(item, cd)) { struct svc_expkey *key = container_of(item, struct svc_expkey, h); if (test_bit(CACHE_VALID, &item->flags) && - !test_bit(CACHE_NEGATIVE, &item->flags)) - exp_put(key->ek_export); + !test_bit(CACHE_NEGATIVE, &item->flags)) { + dput(key->ek_dentry); + mntput(key->ek_mnt); + } auth_domain_put(key->ek_client); kfree(key); } @@ -164,26 +166,18 @@ static int expkey_parse(struct cache_detail *cd, char *mesg, int mlen) } else { struct nameidata nd; struct svc_expkey *ek; - struct svc_export *exp; err = path_lookup(buf, 0, &nd); if (err) goto out; dprintk("Found the path %s\n", buf); - exp = exp_get_by_name(dom, nd.mnt, nd.dentry, NULL); - - err = -ENOENT; - if (!exp) - goto out_nd; - key.ek_export = exp; - dprintk("And found export\n"); + key.ek_mnt = nd.mnt; + key.ek_dentry = nd.dentry; ek = svc_expkey_lookup(&key, 1); if (ek) expkey_put(&ek->h, &svc_expkey_cache); - exp_put(exp); err = 0; - out_nd: path_release(&nd); } cache_flush(); @@ -214,7 +208,7 @@ static int expkey_show(struct seq_file *m, if (test_bit(CACHE_VALID, &h->flags) && !test_bit(CACHE_NEGATIVE, &h->flags)) { seq_printf(m, " "); - seq_path(m, ek->ek_export->ex_mnt, ek->ek_export->ex_dentry, "\\ \t\n"); + seq_path(m, ek->ek_mnt, ek->ek_dentry, "\\ \t\n"); } seq_printf(m, "\n"); return 0; @@ -252,8 +246,8 @@ static inline void svc_expkey_init(struct svc_expkey *new, struct svc_expkey *it static inline void svc_expkey_update(struct svc_expkey *new, struct svc_expkey *item) { - cache_get(&item->ek_export->h); - new->ek_export = item->ek_export; + new->ek_mnt = mntget(item->ek_mnt); + new->ek_dentry = dget(item->ek_dentry); } static DefineSimpleCacheLookup(svc_expkey,0) /* no inplace updates */ @@ -519,7 +513,8 @@ static int exp_set_key(svc_client *clp, int fsid_type, u32 *fsidv, key.ek_client = clp; key.ek_fsidtype = fsid_type; memcpy(key.ek_fsid, fsidv, key_len(fsid_type)); - key.ek_export = exp; + key.ek_mnt = exp->ex_mnt; + key.ek_dentry = exp->ex_dentry; key.h.expiry_time = NEVER; key.h.flags = 0; @@ -741,8 +736,8 @@ exp_export(struct nfsctl_export *nxp) if ((nxp->ex_flags & NFSEXP_FSID) && (fsid_key = exp_get_fsid_key(clp, nxp->ex_dev)) && !IS_ERR(fsid_key) && - fsid_key->ek_export && - fsid_key->ek_export != exp) + fsid_key->ek_mnt && + (fsid_key->ek_mnt != nd.mnt || fsid_key->ek_dentry != nd.dentry) ) goto finish; if (exp) { @@ -912,6 +907,24 @@ out: return err; } +struct svc_export * +exp_find(struct auth_domain *clp, int fsid_type, u32 *fsidv, + struct cache_req *reqp) +{ + struct svc_export *exp; + struct svc_expkey *ek = exp_find_key(clp, fsid_type, fsidv, reqp); + if (!ek || IS_ERR(ek)) + return ERR_PTR(PTR_ERR(ek)); + + exp = exp_get_by_name(clp, ek->ek_mnt, ek->ek_dentry, reqp); + expkey_put(&ek->h, &svc_expkey_cache); + + if (!exp || IS_ERR(exp)) + return ERR_PTR(PTR_ERR(exp)); + return exp; +} + + /* * Called when we need the filehandle for the root of the pseudofs, * for a given NFSv4 client. The root is defined to be the @@ -922,6 +935,7 @@ exp_pseudoroot(struct auth_domain *clp, struct svc_fh *fhp, struct cache_req *creq) { struct svc_expkey *fsid_key; + struct svc_export *exp; int rv; u32 fsidv[2]; @@ -933,8 +947,14 @@ exp_pseudoroot(struct auth_domain *clp, struct svc_fh *fhp, if (!fsid_key || IS_ERR(fsid_key)) return nfserr_perm; - rv = fh_compose(fhp, fsid_key->ek_export, - fsid_key->ek_export->ex_dentry, NULL); + exp = exp_get_by_name(clp, fsid_key->ek_mnt, fsid_key->ek_dentry, creq); + if (exp == NULL) + rv = nfserr_perm; + else if (IS_ERR(exp)) + rv = nfserrno(PTR_ERR(exp)); + else + rv = fh_compose(fhp, exp, + fsid_key->ek_dentry, NULL); expkey_put(&fsid_key->h, &svc_expkey_cache); return rv; } diff --git a/include/linux/nfsd/export.h b/include/linux/nfsd/export.h index 6bad476..d52e0b7 100644 --- a/include/linux/nfsd/export.h +++ b/include/linux/nfsd/export.h @@ -67,7 +67,8 @@ struct svc_expkey { int ek_fsidtype; u32 ek_fsid[3]; - struct svc_export * ek_export; + struct vfsmount * ek_mnt; + struct dentry * ek_dentry; }; #define EX_SECURE(exp) (!((exp)->ex_flags & NFSEXP_INSECURE_PORT)) @@ -114,22 +115,9 @@ static inline void exp_get(struct svc_export *exp) { cache_get(&exp->h); } -static inline struct svc_export * +extern struct svc_export * exp_find(struct auth_domain *clp, int fsid_type, u32 *fsidv, - struct cache_req *reqp) -{ - struct svc_expkey *ek = exp_find_key(clp, fsid_type, fsidv, reqp); - if (ek && !IS_ERR(ek)) { - struct svc_export *exp = ek->ek_export; - int err; - exp_get(exp); - expkey_put(&ek->h, &svc_expkey_cache); - if ((err = cache_check(&svc_export_cache, &exp->h, reqp))) - exp = ERR_PTR(err); - return exp; - } else - return ERR_PTR(PTR_ERR(ek)); -} + struct cache_req *reqp); #endif /* __KERNEL__ */ -- 2.7.4