[PATCH 4/7] nfsd: reorganize nfsd_create

J. Bruce Fields
2016-07-22T17:49:13Z

From: "J. Bruce Fields" <bfields@redhat.com>

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>
---
fs/nfsd/nfsproc.c | 4 +-
fs/nfsd/vfs.c | 109 ++++++++++++++++++++++++++++--------------------------
fs/nfsd/vfs.h | 3 ++
3 files changed, 61 insertions(+), 55 deletions(-)

diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index c30b12388bf6..8914206c867c 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -358,8 +358,8 @@ 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);
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 7ae3b5a72a4d..9c7830cdaeda 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -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

/*
diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index 2d573ec057f8..3cbb1b33777b 100644
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -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);
--
2.7.4