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Subject[PATCH 001 of 20] knfsd: nfsd: make all exp_finding functions return -errno's on err

From: J. Bruce Fields <bfields@puzzle.fieldses.org>

Currently exp_find(), exp_get_by_name(), and friends, return an export on
success, and on failure return:

errors -EAGAIN (drop this request pending an upcall) or
-ETIMEDOUT (an upcall has timed out), or
return NULL, which can mean either that there was a memory allocation
failure, or that an export was not found, or that a passed-in
export lacks an auth_domain.

Many callers seem to assume that NULL means that an export was not found, which
may lead to bugs in the case of a memory allocation failure.

Modify these functions to distinguish between the two NULL cases by returning
either -ENOENT or -ENOMEM. They now never return NULL. We get to simplify
some code in the process.

We return -ENOENT in the case of a missing auth_domain. This case should
probably be removed (or converted to a bug) after confirming that it can never
happen.

Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>

### Diffstat output
./fs/nfsd/export.c | 58 +++++++++++++++++++++--------------------------------
./fs/nfsd/nfsfh.c | 11 ++++------
./fs/nfsd/vfs.c | 9 +++-----
3 files changed, 32 insertions(+), 46 deletions(-)

diff .prev/fs/nfsd/export.c ./fs/nfsd/export.c
--- .prev/fs/nfsd/export.c 2007-07-10 11:19:59.000000000 +1000
+++ ./fs/nfsd/export.c 2007-07-10 11:20:09.000000000 +1000
@@ -739,16 +739,18 @@ exp_find_key(svc_client *clp, int fsid_t
int err;

if (!clp)
- return NULL;
+ return ERR_PTR(-ENOENT);

key.ek_client = clp;
key.ek_fsidtype = fsid_type;
memcpy(key.ek_fsid, fsidv, key_len(fsid_type));

ek = svc_expkey_lookup(&key);
- if (ek != NULL)
- if ((err = cache_check(&svc_expkey_cache, &ek->h, reqp)))
- ek = ERR_PTR(err);
+ if (ek == NULL)
+ return ERR_PTR(-ENOMEM);
+ err = cache_check(&svc_expkey_cache, &ek->h, reqp);
+ if (err)
+ return ERR_PTR(err);
return ek;
}

@@ -809,30 +811,21 @@ exp_get_by_name(svc_client *clp, struct
struct cache_req *reqp)
{
struct svc_export *exp, key;
+ int err;

if (!clp)
- return NULL;
+ return ERR_PTR(-ENOENT);

key.ex_client = clp;
key.ex_mnt = mnt;
key.ex_dentry = dentry;

exp = svc_export_lookup(&key);
- if (exp != NULL) {
- int err;
-
- err = cache_check(&svc_export_cache, &exp->h, reqp);
- switch (err) {
- case 0: break;
- case -EAGAIN:
- case -ETIMEDOUT:
- exp = ERR_PTR(err);
- break;
- default:
- exp = NULL;
- }
- }
-
+ if (exp == NULL)
+ return ERR_PTR(-ENOMEM);
+ err = cache_check(&svc_export_cache, &exp->h, reqp);
+ if (err)
+ return ERR_PTR(err);
return exp;
}

@@ -848,7 +841,7 @@ exp_parent(svc_client *clp, struct vfsmo
dget(dentry);
exp = exp_get_by_name(clp, mnt, dentry, reqp);

- while (exp == NULL && !IS_ROOT(dentry)) {
+ while (PTR_ERR(exp) == -ENOENT && !IS_ROOT(dentry)) {
struct dentry *parent;

parent = dget_parent(dentry);
@@ -901,7 +894,7 @@ static void exp_fsid_unhash(struct svc_e
return;

ek = exp_get_fsid_key(exp->ex_client, exp->ex_fsid);
- if (ek && !IS_ERR(ek)) {
+ if (!IS_ERR(ek)) {
ek->h.expiry_time = get_seconds()-1;
cache_put(&ek->h, &svc_expkey_cache);
}
@@ -939,7 +932,7 @@ static void exp_unhash(struct svc_export
struct inode *inode = exp->ex_dentry->d_inode;

ek = exp_get_key(exp->ex_client, inode->i_sb->s_dev, inode->i_ino);
- if (ek && !IS_ERR(ek)) {
+ if (!IS_ERR(ek)) {
ek->h.expiry_time = get_seconds()-1;
cache_put(&ek->h, &svc_expkey_cache);
}
@@ -990,13 +983,12 @@ exp_export(struct nfsctl_export *nxp)

/* must make sure there won't be an ex_fsid clash */
if ((nxp->ex_flags & NFSEXP_FSID) &&
- (fsid_key = exp_get_fsid_key(clp, nxp->ex_dev)) &&
- !IS_ERR(fsid_key) &&
+ (!IS_ERR(fsid_key = exp_get_fsid_key(clp, nxp->ex_dev))) &&
fsid_key->ek_mnt &&
(fsid_key->ek_mnt != nd.mnt || fsid_key->ek_dentry != nd.dentry) )
goto finish;

- if (exp) {
+ if (!IS_ERR(exp)) {
/* just a flags/id/fsid update */

exp_fsid_unhash(exp);
@@ -1105,7 +1097,7 @@ exp_unexport(struct nfsctl_export *nxp)
err = -EINVAL;
exp = exp_get_by_name(dom, nd.mnt, nd.dentry, NULL);
path_release(&nd);
- if (!exp)
+ if (IS_ERR(exp))
goto out_domain;

exp_do_unexport(exp);
@@ -1150,10 +1142,6 @@ exp_rootfh(svc_client *clp, char *path,
err = PTR_ERR(exp);
goto out;
}
- if (!exp) {
- dprintk("nfsd: exp_rootfh export not found.\n");
- goto out;
- }

/*
* fh must be initialized before calling fh_compose
@@ -1177,13 +1165,13 @@ exp_find(struct auth_domain *clp, int fs
{
struct svc_export *exp;
struct svc_expkey *ek = exp_find_key(clp, fsid_type, fsidv, reqp);
- if (!ek || IS_ERR(ek))
+ if (IS_ERR(ek))
return ERR_PTR(PTR_ERR(ek));

exp = exp_get_by_name(clp, ek->ek_mnt, ek->ek_dentry, reqp);
cache_put(&ek->h, &svc_expkey_cache);

- if (!exp || IS_ERR(exp))
+ if (IS_ERR(exp))
return ERR_PTR(PTR_ERR(exp));
return exp;
}
@@ -1205,10 +1193,10 @@ exp_pseudoroot(struct auth_domain *clp,
mk_fsid(FSID_NUM, fsidv, 0, 0, 0, NULL);

exp = exp_find(clp, FSID_NUM, fsidv, creq);
+ if (PTR_ERR(exp) == -ENOENT)
+ return nfserr_perm;
if (IS_ERR(exp))
return nfserrno(PTR_ERR(exp));
- if (exp == NULL)
- return nfserr_perm;
rv = fh_compose(fhp, exp, exp->ex_dentry, NULL);
exp_put(exp);
return rv;
diff .prev/fs/nfsd/nfsfh.c ./fs/nfsd/nfsfh.c
--- .prev/fs/nfsd/nfsfh.c 2007-07-10 11:19:59.000000000 +1000
+++ ./fs/nfsd/nfsfh.c 2007-07-10 11:20:09.000000000 +1000
@@ -160,15 +160,14 @@ fh_verify(struct svc_rqst *rqstp, struct
&rqstp->rq_chandle);
}

- if (IS_ERR(exp) && (PTR_ERR(exp) == -EAGAIN
- || PTR_ERR(exp) == -ETIMEDOUT)) {
- error = nfserrno(PTR_ERR(exp));
+ error = nfserr_stale;
+ if (PTR_ERR(exp) == -ENOENT)
goto out;
- }

- error = nfserr_stale;
- if (!exp || IS_ERR(exp))
+ if (IS_ERR(exp)) {
+ error = nfserrno(PTR_ERR(exp));
goto out;
+ }

/* Check if the request originated from a secure port. */
error = nfserr_perm;
diff .prev/fs/nfsd/vfs.c ./fs/nfsd/vfs.c
--- .prev/fs/nfsd/vfs.c 2007-07-10 11:19:59.000000000 +1000
+++ ./fs/nfsd/vfs.c 2007-07-10 11:20:09.000000000 +1000
@@ -192,15 +192,14 @@ nfsd_lookup(struct svc_rqst *rqstp, stru

exp2 = exp_parent(exp->ex_client, mnt, dentry,
&rqstp->rq_chandle);
- if (IS_ERR(exp2)) {
+ if (PTR_ERR(exp2) == -ENOENT) {
+ dput(dentry);
+ dentry = dget(dparent);
+ } else if (IS_ERR(exp2)) {
host_err = PTR_ERR(exp2);
dput(dentry);
mntput(mnt);
goto out_nfserr;
- }
- if (!exp2) {
- dput(dentry);
- dentry = dget(dparent);
} else {
exp_put(exp);
exp = exp2;
-
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