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nfsd: reorganize nfsd_create

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There's some odd logic in nfsd_create() that allows it to be called with
the parent directory either locked or unlocked.  The only already-locked
caller is NFSv2's nfsd_proc_create().  It's less confusing to split out
the unlocked case into a separate function which the NFSv2 code can call
directly.

Also fix some comments while we're here.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
J. Bruce Fields 2016-07-20 16:16:06 -04:00
parent e75b23f9e3
commit b44061d0b9
3 changed files with 61 additions and 55 deletions
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4
fs/nfsd/nfsproc.c
View File

@ -359,8 +359,8 @@ nfsd_proc_create(struct svc_rqst *rqstp, struct nfsd_createargs *argp,
nfserr = 0;
if (!inode) {
/* File doesn't exist. Create it and set attrs */
nfserr = nfsd_create(rqstp, dirfhp, argp->name, argp->len,
attr, type, rdev, newfhp);
nfserr = nfsd_create_locked(rqstp, dirfhp, argp->name,
argp->len, attr, type, rdev, newfhp);
} else if (type == S_IFREG) {
dprintk("nfsd: existing %s, valid=%x, size=%ld\n",
argp->name, attr->ia_valid, (long) attr->ia_size);

109
fs/nfsd/vfs.c
View File

@ -1135,16 +1135,9 @@ nfsd_check_ignore_resizing(struct iattr *iap)
iap->ia_valid &= ~ATTR_SIZE;
}
/*
* Create a file (regular, directory, device, fifo); UNIX sockets
* not yet implemented.
* If the response fh has been verified, the parent directory should
* already be locked. Note that the parent directory is left locked.
*
* N.B. Every call to nfsd_create needs an fh_put for _both_ fhp and resfhp
*/
/* The parent directory should already be locked: */
__be32
nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
char *fname, int flen, struct iattr *iap,
int type, dev_t rdev, struct svc_fh *resfhp)
{
@ -1154,50 +1147,15 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
__be32 err2;
int host_err;
err = nfserr_exist;
if (isdotent(fname, flen))
goto out;
/*
* Even though it is a create, first let's see if we are even allowed
* to peek inside the parent
*/
err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
if (err)
goto out;
dentry = fhp->fh_dentry;
dirp = d_inode(dentry);
/*
* Check whether the response file handle has been verified yet.
* If it has, the parent directory should already be locked.
*/
if (!resfhp->fh_dentry) {
host_err = fh_want_write(fhp);
if (host_err)
goto out_nfserr;
/* called from nfsd_proc_mkdir, or possibly nfsd3_proc_create */
fh_lock_nested(fhp, I_MUTEX_PARENT);
dchild = lookup_one_len(fname, dentry, flen);
host_err = PTR_ERR(dchild);
if (IS_ERR(dchild))
goto out_nfserr;
err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
if (err)
goto out;
} else {
/* called from nfsd_proc_create */
dchild = dget(resfhp->fh_dentry);
if (!fhp->fh_locked) {
/* not actually possible */
printk(KERN_ERR
"nfsd_create: parent %pd2 not locked!\n",
dchild = dget(resfhp->fh_dentry);
if (!fhp->fh_locked) {
WARN_ONCE(1, "nfsd_create: parent %pd2 not locked!\n",
dentry);
err = nfserr_io;
goto out;
}
err = nfserr_io;
goto out;
}
/*
* Make sure the child dentry is still negative ...
@ -1225,9 +1183,6 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
goto out;
}
/*
* Get the dir op function pointer.
*/
err = 0;
host_err = 0;
switch (type) {
@ -1254,7 +1209,7 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
/*
* nfsd_create_setattr already committed the child. Transactional
* filesystems had a chance to commit changes for both parent and
* child * simultaneously making the following commit_metadata a
* child simultaneously making the following commit_metadata a
* noop.
*/
err2 = nfserrno(commit_metadata(fhp));
@ -1275,6 +1230,54 @@ out_nfserr:
goto out;
}
/*
* Create a filesystem object (regular, directory, special).
* Note that the parent directory is left locked.
*
* N.B. Every call to nfsd_create needs an fh_put for _both_ fhp and resfhp
*/
__be32
nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
char *fname, int flen, struct iattr *iap,
int type, dev_t rdev, struct svc_fh *resfhp)
{
struct dentry *dentry, *dchild = NULL;
struct inode *dirp;
__be32 err;
int host_err;
if (isdotent(fname, flen))
return nfserr_exist;
/*
* Even though it is a create, first let's see if we are even allowed
* to peek inside the parent
*/
err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
if (err)
return err;
dentry = fhp->fh_dentry;
dirp = d_inode(dentry);
host_err = fh_want_write(fhp);
if (host_err)
return nfserrno(host_err);
fh_lock_nested(fhp, I_MUTEX_PARENT);
dchild = lookup_one_len(fname, dentry, flen);
host_err = PTR_ERR(dchild);
if (IS_ERR(dchild))
return nfserrno(host_err);
err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
if (err) {
dput(dchild);
return err;
}
return nfsd_create_locked(rqstp, fhp, fname, flen, iap, type,
rdev, resfhp);
}
#ifdef CONFIG_NFSD_V3
/*

3
fs/nfsd/vfs.h
View File

@ -59,6 +59,9 @@ __be32 nfsd4_vfs_fallocate(struct svc_rqst *, struct svc_fh *,
__be32 nfsd4_clone_file_range(struct file *, u64, struct file *,
u64, u64);
#endif /* CONFIG_NFSD_V4 */
__be32 nfsd_create_locked(struct svc_rqst *, struct svc_fh *,
char *name, int len, struct iattr *attrs,
int type, dev_t rdev, struct svc_fh *res);
__be32 nfsd_create(struct svc_rqst *, struct svc_fh *,
char *name, int len, struct iattr *attrs,
int type, dev_t rdev, struct svc_fh *res);