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NFS: Refactor nfs_instantiate() for dentry referencing callers

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Since commit b0c6108ecf ("nfs_instantiate(): prevent multiple aliases for
directory inode"), nfs_instantiate() may succeed without actually
instantiating the dentry that was passed in.  That can be problematic for
some callers in NFSv3, so this patch breaks things up so we can get the
actual dentry obtained.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Benjamin Coddington 2019-09-13 08:29:02 -04:00 committed by Anna Schumaker
parent 8593e01078
commit 406cd91533
2 changed files with 30 additions and 14 deletions
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41
fs/nfs/dir.c
View File

@ -1669,24 +1669,23 @@ static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)
#endif /* CONFIG_NFSV4 */
/*
* Code common to create, mkdir, and mknod.
*/
int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle,
struct dentry *
nfs_add_or_obtain(struct dentry *dentry, struct nfs_fh *fhandle,
struct nfs_fattr *fattr,
struct nfs4_label *label)
{
struct dentry *parent = dget_parent(dentry);
struct inode *dir = d_inode(parent);
struct inode *inode;
struct dentry *d;
int error = -EACCES;
struct dentry *d = NULL;
int error;
d_drop(dentry);
/* We may have been initialized further down */
if (d_really_is_positive(dentry))
goto out;
if (fhandle->size == 0) {
error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, NULL);
if (error)
@ -1702,18 +1701,32 @@ int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle,
}
inode = nfs_fhget(dentry->d_sb, fhandle, fattr, label);
d = d_splice_alias(inode, dentry);
if (IS_ERR(d)) {
error = PTR_ERR(d);
goto out_error;
}
dput(d);
out:
dput(parent);
return 0;
return d;
out_error:
nfs_mark_for_revalidate(dir);
dput(parent);
return error;
d = ERR_PTR(error);
goto out;
}
EXPORT_SYMBOL_GPL(nfs_add_or_obtain);
/*
* Code common to create, mkdir, and mknod.
*/
int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle,
struct nfs_fattr *fattr,
struct nfs4_label *label)
{
struct dentry *d;
d = nfs_add_or_obtain(dentry, fhandle, fattr, label);
if (IS_ERR(d))
return PTR_ERR(d);
/* Callers don't care */
dput(d);
return 0;
}
EXPORT_SYMBOL_GPL(nfs_instantiate);

3
include/linux/nfs_fs.h
View File

@ -490,6 +490,9 @@ extern const struct file_operations nfs_dir_operations;
extern const struct dentry_operations nfs_dentry_operations;
extern void nfs_force_lookup_revalidate(struct inode *dir);
extern struct dentry *nfs_add_or_obtain(struct dentry *dentry,
struct nfs_fh *fh, struct nfs_fattr *fattr,
struct nfs4_label *label);
extern int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fh,
struct nfs_fattr *fattr, struct nfs4_label *label);
extern int nfs_may_open(struct inode *inode, const struct cred *cred, int openflags);