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authorJ. Bruce Fields <bfields@redhat.com>2011-09-20 17:14:31 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2013-11-09 00:16:43 -0500
commit146a8595c6399ee6ab4b5cc34c0d28aa4835fdc5 (patch)
treea16a703ef40d72912247d496cd2e3cb7c0f3b9a7
parent8e6d782cab50884ba94324632700e6233a252f6a (diff)
downloadlinux-linaro-stable-146a8595c6399ee6ab4b5cc34c0d28aa4835fdc5.tar.gz
locks: break delegations on link
Cc: Tyler Hicks <tyhicks@canonical.com> Cc: Dustin Kirkland <dustin.kirkland@gazzang.com> Acked-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/ecryptfs/inode.c2
-rw-r--r--fs/namei.c36
-rw-r--r--fs/nfsd/vfs.c2
-rw-r--r--include/linux/fs.h2
4 files changed, 35 insertions, 7 deletions
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index c23b01bb7e04..1c628f023041 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -475,7 +475,7 @@ static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
dget(lower_new_dentry);
lower_dir_dentry = lock_parent(lower_new_dentry);
rc = vfs_link(lower_old_dentry, lower_dir_dentry->d_inode,
- lower_new_dentry);
+ lower_new_dentry, NULL);
if (rc || !lower_new_dentry->d_inode)
goto out_lock;
rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb);
diff --git a/fs/namei.c b/fs/namei.c
index ce7e580e4e14..251178a1e383 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3819,7 +3819,26 @@ SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newn
return sys_symlinkat(oldname, AT_FDCWD, newname);
}
-int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
+/**
+ * vfs_link - create a new link
+ * @old_dentry: object to be linked
+ * @dir: new parent
+ * @new_dentry: where to create the new link
+ * @delegated_inode: returns inode needing a delegation break
+ *
+ * The caller must hold dir->i_mutex
+ *
+ * If vfs_link discovers a delegation on the to-be-linked file in need
+ * of breaking, it will return -EWOULDBLOCK and return a reference to the
+ * inode in delegated_inode. The caller should then break the delegation
+ * and retry. Because breaking a delegation may take a long time, the
+ * caller should drop the i_mutex before doing so.
+ *
+ * Alternatively, a caller may pass NULL for delegated_inode. This may
+ * be appropriate for callers that expect the underlying filesystem not
+ * to be NFS exported.
+ */
+int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode)
{
struct inode *inode = old_dentry->d_inode;
unsigned max_links = dir->i_sb->s_max_links;
@@ -3855,8 +3874,11 @@ int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_de
error = -ENOENT;
else if (max_links && inode->i_nlink >= max_links)
error = -EMLINK;
- else
- error = dir->i_op->link(old_dentry, dir, new_dentry);
+ else {
+ error = try_break_deleg(inode, delegated_inode);
+ if (!error)
+ error = dir->i_op->link(old_dentry, dir, new_dentry);
+ }
if (!error && (inode->i_state & I_LINKABLE)) {
spin_lock(&inode->i_lock);
@@ -3883,6 +3905,7 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
{
struct dentry *new_dentry;
struct path old_path, new_path;
+ struct inode *delegated_inode = NULL;
int how = 0;
int error;
@@ -3921,9 +3944,14 @@ retry:
error = security_path_link(old_path.dentry, &new_path, new_dentry);
if (error)
goto out_dput;
- error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry);
+ error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode);
out_dput:
done_path_create(&new_path, new_dentry);
+ if (delegated_inode) {
+ error = break_deleg_wait(&delegated_inode);
+ if (!error)
+ goto retry;
+ }
if (retry_estale(error, how)) {
how |= LOOKUP_REVAL;
goto retry;
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 45bf0295894d..27ba21b5f383 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1736,7 +1736,7 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
err = nfserrno(host_err);
goto out_dput;
}
- host_err = vfs_link(dold, dirp, dnew);
+ host_err = vfs_link(dold, dirp, dnew, NULL);
if (!host_err) {
err = nfserrno(commit_metadata(ffhp));
if (!err)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 5bcff883fa90..6e36e7118ec1 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1453,7 +1453,7 @@ extern int vfs_create(struct inode *, struct dentry *, umode_t, bool);
extern int vfs_mkdir(struct inode *, struct dentry *, umode_t);
extern int vfs_mknod(struct inode *, struct dentry *, umode_t, dev_t);
extern int vfs_symlink(struct inode *, struct dentry *, const char *);
-extern int vfs_link(struct dentry *, struct inode *, struct dentry *);
+extern int vfs_link(struct dentry *, struct inode *, struct dentry *, struct inode **);
extern int vfs_rmdir(struct inode *, struct dentry *);
extern int vfs_unlink(struct inode *, struct dentry *, struct inode **);
extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *, struct inode **);