Merge uncontroversial parts of branch 'readlink' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull partial readlink cleanups from Miklos Szeredi.

This is the uncontroversial part of the readlink cleanup patch-set that
simplifies the default readlink handling.

Miklos and Al are still discussing the rest of the series.

* git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  vfs: make generic_readlink() static
  vfs: remove ".readlink = generic_readlink" assignments
  vfs: default to generic_readlink()
  vfs: replace calling i_op->readlink with vfs_readlink()
  proc/self: use generic_readlink
  ecryptfs: use vfs_get_link()
  bad_inode: add missing i_op initializers

Documentation/filesystems/porting

@@ -596,3 +596,7 @@ in your dentry operations instead.
 [mandatory]
 	->rename() has an added flags argument.  Any flags not handled by the
         filesystem should result in EINVAL being returned.
+--
+[recommended]
+	->readlink is optional for symlinks.  Don't set, unless filesystem needs
+	to fake something for readlink(2).

Documentation/filesystems/vfs.txt

@@ -451,9 +451,6 @@ otherwise noted.
 	exist; this is checked by the VFS.  Unlike plain rename,
 	source and target may be of different type.
 
-  readlink: called by the readlink(2) system call. Only required if
-	you want to support reading symbolic links
-
   get_link: called by the VFS to follow a symbolic link to the
 	inode it points to.  Only required if you want to support
 	symbolic links.  This method returns the symlink body
@@ -468,6 +465,12 @@ otherwise noted.
 	argument.  If request can't be handled without leaving RCU mode,
 	have it return ERR_PTR(-ECHILD).
 
+  readlink: this is now just an override for use by readlink(2) for the
+	cases when ->get_link uses nd_jump_link() or object is not in
+	fact a symlink.  Normally filesystems should only implement
+	->get_link for symlinks and readlink(2) will automatically use
+	that.
+
   permission: called by the VFS to check for access rights on a POSIX-like
   	filesystem.
 

drivers/staging/lustre/lustre/llite/symlink.c

@@ -149,7 +149,6 @@ static const char *ll_get_link(struct dentry *dentry,
 }
 
 const struct inode_operations ll_fast_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.setattr	= ll_setattr,
 	.get_link	= ll_get_link,
 	.getattr	= ll_getattr,

fs/9p/vfs_inode.c

@@ -1464,7 +1464,6 @@ static const struct inode_operations v9fs_file_inode_operations = {
 };
 
 static const struct inode_operations v9fs_symlink_inode_operations = {
-	.readlink = generic_readlink,
 	.get_link = v9fs_vfs_get_link,
 	.getattr = v9fs_vfs_getattr,
 	.setattr = v9fs_vfs_setattr,

fs/9p/vfs_inode_dotl.c

@@ -979,7 +979,6 @@ const struct inode_operations v9fs_file_inode_operations_dotl = {
 };
 
 const struct inode_operations v9fs_symlink_inode_operations_dotl = {
-	.readlink = generic_readlink,
 	.get_link = v9fs_vfs_get_link_dotl,
 	.getattr = v9fs_vfs_getattr_dotl,
 	.setattr = v9fs_vfs_setattr_dotl,

fs/affs/symlink.c

@@ -70,7 +70,6 @@ const struct address_space_operations affs_symlink_aops = {
 };
 
 const struct inode_operations affs_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
 	.setattr	= affs_notify_change,
 };

fs/autofs4/symlink.c

@@ -25,6 +25,5 @@ static const char *autofs4_get_link(struct dentry *dentry,
 }
 
 const struct inode_operations autofs4_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= autofs4_get_link
 };

fs/bad_inode.c

@@ -106,6 +106,50 @@ static ssize_t bad_inode_listxattr(struct dentry *dentry, char *buffer,
 	return -EIO;
 }
 
+static const char *bad_inode_get_link(struct dentry *dentry,
+				      struct inode *inode,
+				      struct delayed_call *done)
+{
+	return ERR_PTR(-EIO);
+}
+
+static struct posix_acl *bad_inode_get_acl(struct inode *inode, int type)
+{
+	return ERR_PTR(-EIO);
+}
+
+static int bad_inode_fiemap(struct inode *inode,
+			    struct fiemap_extent_info *fieinfo, u64 start,
+			    u64 len)
+{
+	return -EIO;
+}
+
+static int bad_inode_update_time(struct inode *inode, struct timespec *time,
+				 int flags)
+{
+	return -EIO;
+}
+
+static int bad_inode_atomic_open(struct inode *inode, struct dentry *dentry,
+				 struct file *file, unsigned int open_flag,
+				 umode_t create_mode, int *opened)
+{
+	return -EIO;
+}
+
+static int bad_inode_tmpfile(struct inode *inode, struct dentry *dentry,
+			     umode_t mode)
+{
+	return -EIO;
+}
+
+static int bad_inode_set_acl(struct inode *inode, struct posix_acl *acl,
+			     int type)
+{
+	return -EIO;
+}
+
 static const struct inode_operations bad_inode_ops =
 {
 	.create		= bad_inode_create,
@@ -118,14 +162,17 @@ static const struct inode_operations bad_inode_ops =
 	.mknod		= bad_inode_mknod,
 	.rename		= bad_inode_rename2,
 	.readlink	= bad_inode_readlink,
-	/* follow_link must be no-op, otherwise unmounting this inode
-	   won't work */
-	/* put_link returns void */
-	/* truncate returns void */
 	.permission	= bad_inode_permission,
 	.getattr	= bad_inode_getattr,
 	.setattr	= bad_inode_setattr,
 	.listxattr	= bad_inode_listxattr,
+	.get_link	= bad_inode_get_link,
+	.get_acl	= bad_inode_get_acl,
+	.fiemap		= bad_inode_fiemap,
+	.update_time	= bad_inode_update_time,
+	.atomic_open	= bad_inode_atomic_open,
+	.tmpfile	= bad_inode_tmpfile,
+	.set_acl	= bad_inode_set_acl,
 };
 
 

fs/btrfs/inode.c

@@ -10653,7 +10653,6 @@ static const struct inode_operations btrfs_special_inode_operations = {
 	.update_time	= btrfs_update_time,
 };
 static const struct inode_operations btrfs_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
 	.getattr	= btrfs_getattr,
 	.setattr	= btrfs_setattr,

fs/ceph/inode.c

@@ -1869,7 +1869,6 @@ retry:
  * symlinks
  */
 static const struct inode_operations ceph_symlink_iops = {
-	.readlink = generic_readlink,
 	.get_link = simple_get_link,
 	.setattr = ceph_setattr,
 	.getattr = ceph_getattr,

fs/cifs/cifsfs.c

@@ -914,7 +914,6 @@ const struct inode_operations cifs_file_inode_ops = {
 };
 
 const struct inode_operations cifs_symlink_inode_ops = {
-	.readlink = generic_readlink,
 	.get_link = cifs_get_link,
 	.permission = cifs_permission,
 	.listxattr = cifs_listxattr,

fs/coda/cnode.c

@@ -17,7 +17,6 @@ static inline int coda_fideq(struct CodaFid *fid1, struct CodaFid *fid2)
 }
 
 static const struct inode_operations coda_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
 	.setattr	= coda_setattr,
 };

fs/configfs/symlink.c

@@ -305,7 +305,6 @@ static const char *configfs_get_link(struct dentry *dentry,
 
 const struct inode_operations configfs_symlink_inode_operations = {
 	.get_link = configfs_get_link,
-	.readlink = generic_readlink,
 	.setattr = configfs_setattr,
 };
 

fs/ecryptfs/inode.c

@@ -631,28 +631,23 @@ out_lock:
 
 static char *ecryptfs_readlink_lower(struct dentry *dentry, size_t *bufsiz)
 {
+	DEFINE_DELAYED_CALL(done);
 	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
-	char *lower_buf;
+	const char *link;
 	char *buf;
-	mm_segment_t old_fs;
 	int rc;
 
-	lower_buf = kmalloc(PATH_MAX, GFP_KERNEL);
-	if (!lower_buf)
-		return ERR_PTR(-ENOMEM);
-	old_fs = get_fs();
-	set_fs(get_ds());
-	rc = d_inode(lower_dentry)->i_op->readlink(lower_dentry,
-						   (char __user *)lower_buf,
-						   PATH_MAX);
-	set_fs(old_fs);
-	if (rc < 0)
-		goto out;
+	link = vfs_get_link(lower_dentry, &done);
+	if (IS_ERR(link))
+		return ERR_CAST(link);
+
 	rc = ecryptfs_decode_and_decrypt_filename(&buf, bufsiz, dentry->d_sb,
-						  lower_buf, rc);
-out:
-	kfree(lower_buf);
-	return rc ? ERR_PTR(rc) : buf;
+						  link, strlen(link));
+	do_delayed_call(&done);
+	if (rc)
+		return ERR_PTR(rc);
+
+	return buf;
 }
 
 static const char *ecryptfs_get_link(struct dentry *dentry,
@@ -1089,7 +1084,6 @@ out:
 }
 
 const struct inode_operations ecryptfs_symlink_iops = {
-	.readlink = generic_readlink,
 	.get_link = ecryptfs_get_link,
 	.permission = ecryptfs_permission,
 	.setattr = ecryptfs_setattr,

fs/ext2/symlink.c

@@ -21,7 +21,6 @@
 #include "xattr.h"
 
 const struct inode_operations ext2_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
 	.setattr	= ext2_setattr,
 #ifdef CONFIG_EXT2_FS_XATTR
@@ -30,7 +29,6 @@ const struct inode_operations ext2_symlink_inode_operations = {
 };
  
 const struct inode_operations ext2_fast_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= simple_get_link,
 	.setattr	= ext2_setattr,
 #ifdef CONFIG_EXT2_FS_XATTR

fs/ext4/symlink.c

@@ -83,21 +83,18 @@ errout:
 }
 
 const struct inode_operations ext4_encrypted_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= ext4_encrypted_get_link,
 	.setattr	= ext4_setattr,
 	.listxattr	= ext4_listxattr,
 };
 
 const struct inode_operations ext4_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
 	.setattr	= ext4_setattr,
 	.listxattr	= ext4_listxattr,
 };
 
 const struct inode_operations ext4_fast_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= simple_get_link,
 	.setattr	= ext4_setattr,
 	.listxattr	= ext4_listxattr,

fs/f2fs/namei.c

@@ -1075,7 +1075,6 @@ errout:
 }
 
 const struct inode_operations f2fs_encrypted_symlink_inode_operations = {
-	.readlink       = generic_readlink,
 	.get_link       = f2fs_encrypted_get_link,
 	.getattr	= f2fs_getattr,
 	.setattr	= f2fs_setattr,
@@ -1105,7 +1104,6 @@ const struct inode_operations f2fs_dir_inode_operations = {
 };
 
 const struct inode_operations f2fs_symlink_inode_operations = {
-	.readlink       = generic_readlink,
 	.get_link       = f2fs_get_link,
 	.getattr	= f2fs_getattr,
 	.setattr	= f2fs_setattr,

fs/fuse/dir.c

@@ -1831,7 +1831,6 @@ static const struct inode_operations fuse_common_inode_operations = {
 static const struct inode_operations fuse_symlink_inode_operations = {
 	.setattr	= fuse_setattr,
 	.get_link	= fuse_get_link,
-	.readlink	= generic_readlink,
 	.getattr	= fuse_getattr,
 	.listxattr	= fuse_listxattr,
 };

fs/gfs2/inode.c

@@ -2067,7 +2067,6 @@ const struct inode_operations gfs2_dir_iops = {
 };
 
 const struct inode_operations gfs2_symlink_iops = {
-	.readlink = generic_readlink,
 	.get_link = gfs2_get_link,
 	.permission = gfs2_permission,
 	.setattr = gfs2_setattr,

fs/hostfs/hostfs_kern.c

@@ -920,7 +920,6 @@ static const char *hostfs_get_link(struct dentry *dentry,
 }
 
 static const struct inode_operations hostfs_link_iops = {
-	.readlink	= generic_readlink,
 	.get_link	= hostfs_get_link,
 };
 

fs/jffs2/symlink.c

@@ -13,7 +13,6 @@
 
 const struct inode_operations jffs2_symlink_inode_operations =
 {
-	.readlink =	generic_readlink,
 	.get_link =	simple_get_link,
 	.setattr =	jffs2_setattr,
 	.listxattr =	jffs2_listxattr,

fs/jfs/symlink.c

@@ -22,14 +22,12 @@
 #include "jfs_xattr.h"
 
 const struct inode_operations jfs_fast_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= simple_get_link,
 	.setattr	= jfs_setattr,
 	.listxattr	= jfs_listxattr,
 };
 
 const struct inode_operations jfs_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
 	.setattr	= jfs_setattr,
 	.listxattr	= jfs_listxattr,

fs/kernfs/symlink.c

@@ -135,7 +135,6 @@ static const char *kernfs_iop_get_link(struct dentry *dentry,
 
 const struct inode_operations kernfs_symlink_iops = {
 	.listxattr	= kernfs_iop_listxattr,
-	.readlink	= generic_readlink,
 	.get_link	= kernfs_iop_get_link,
 	.setattr	= kernfs_iop_setattr,
 	.getattr	= kernfs_iop_getattr,

fs/libfs.c

@@ -1131,7 +1131,6 @@ EXPORT_SYMBOL(simple_get_link);
 
 const struct inode_operations simple_symlink_inode_operations = {
 	.get_link = simple_get_link,
-	.readlink = generic_readlink
 };
 EXPORT_SYMBOL(simple_symlink_inode_operations);
 

fs/minix/inode.c

@@ -434,7 +434,6 @@ static const struct address_space_operations minix_aops = {
 };
 
 static const struct inode_operations minix_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
 	.getattr	= minix_getattr,
 };

fs/namei.c

@@ -4606,7 +4606,8 @@ out:
  * have ->get_link() not calling nd_jump_link().  Using (or not using) it
  * for any given inode is up to filesystem.
  */
-int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+static int generic_readlink(struct dentry *dentry, char __user *buffer,
+			    int buflen)
 {
 	DEFINE_DELAYED_CALL(done);
 	struct inode *inode = d_inode(dentry);
@@ -4622,7 +4623,36 @@ int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
 	do_delayed_call(&done);
 	return res;
 }
-EXPORT_SYMBOL(generic_readlink);
+
+/**
+ * vfs_readlink - copy symlink body into userspace buffer
+ * @dentry: dentry on which to get symbolic link
+ * @buffer: user memory pointer
+ * @buflen: size of buffer
+ *
+ * Does not touch atime.  That's up to the caller if necessary
+ *
+ * Does not call security hook.
+ */
+int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+{
+	struct inode *inode = d_inode(dentry);
+
+	if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) {
+		if (unlikely(inode->i_op->readlink))
+			return inode->i_op->readlink(dentry, buffer, buflen);
+
+		if (!d_is_symlink(dentry))
+			return -EINVAL;
+
+		spin_lock(&inode->i_lock);
+		inode->i_opflags |= IOP_DEFAULT_READLINK;
+		spin_unlock(&inode->i_lock);
+	}
+
+	return generic_readlink(dentry, buffer, buflen);
+}
+EXPORT_SYMBOL(vfs_readlink);
 
 /**
  * vfs_get_link - get symlink body
@@ -4739,7 +4769,6 @@ int page_symlink(struct inode *inode, const char *symname, int len)
 EXPORT_SYMBOL(page_symlink);
 
 const struct inode_operations page_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
 };
 EXPORT_SYMBOL(page_symlink_inode_operations);

fs/ncpfs/inode.c

@@ -243,7 +243,6 @@ static void ncp_set_attr(struct inode *inode, struct ncp_entry_info *nwinfo)
 
 #if defined(CONFIG_NCPFS_EXTRAS) || defined(CONFIG_NCPFS_NFS_NS)
 static const struct inode_operations ncp_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
 	.setattr	= ncp_notify_change,
 };

fs/nfs/symlink.c

@@ -77,7 +77,6 @@ static const char *nfs_get_link(struct dentry *dentry,
  * symlinks can't do much...
  */
 const struct inode_operations nfs_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= nfs_get_link,
 	.getattr	= nfs_getattr,
 	.setattr	= nfs_setattr,

fs/nfsd/nfs4xdr.c

@@ -3605,10 +3605,10 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd
 	if (!p)
 		return nfserr_resource;
 	/*
-	 * XXX: By default, the ->readlink() VFS op will truncate symlinks
-	 * if they would overflow the buffer.  Is this kosher in NFSv4?  If
-	 * not, one easy fix is: if ->readlink() precisely fills the buffer,
-	 * assume that truncation occurred, and return NFS4ERR_RESOURCE.
+	 * XXX: By default, vfs_readlink() will truncate symlinks if they
+	 * would overflow the buffer.  Is this kosher in NFSv4?  If not, one
+	 * easy fix is: if vfs_readlink() precisely fills the buffer, assume
+	 * that truncation occurred, and return NFS4ERR_RESOURCE.
 	 */
 	nfserr = nfsd_readlink(readlink->rl_rqstp, readlink->rl_fhp,
 						(char *)p, &maxcount);

fs/nfsd/vfs.c

@@ -1450,7 +1450,6 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
 __be32
 nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
 {
-	struct inode	*inode;
 	mm_segment_t	oldfs;
 	__be32		err;
 	int		host_err;
@@ -1462,10 +1461,9 @@ nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
 
 	path.mnt = fhp->fh_export->ex_path.mnt;
 	path.dentry = fhp->fh_dentry;
-	inode = d_inode(path.dentry);
 
 	err = nfserr_inval;
-	if (!inode->i_op->readlink)
+	if (!d_is_symlink(path.dentry))
 		goto out;
 
 	touch_atime(&path);
@@ -1474,7 +1472,7 @@ nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
 	 */
 
 	oldfs = get_fs(); set_fs(KERNEL_DS);
-	host_err = inode->i_op->readlink(path.dentry, (char __user *)buf, *lenp);
+	host_err = vfs_readlink(path.dentry, (char __user *)buf, *lenp);
 	set_fs(oldfs);
 
 	if (host_err < 0)

fs/nilfs2/namei.c

@@ -568,7 +568,6 @@ const struct inode_operations nilfs_special_inode_operations = {
 };
 
 const struct inode_operations nilfs_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
 	.permission     = nilfs_permission,
 };

fs/ocfs2/symlink.c

@@ -87,7 +87,6 @@ const struct address_space_operations ocfs2_fast_symlink_aops = {
 };
 
 const struct inode_operations ocfs2_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
 	.getattr	= ocfs2_getattr,
 	.setattr	= ocfs2_setattr,

fs/orangefs/symlink.c

@@ -9,7 +9,6 @@
 #include "orangefs-bufmap.h"
 
 const struct inode_operations orangefs_symlink_inode_operations = {
-	.readlink = generic_readlink,
 	.get_link = simple_get_link,
 	.setattr = orangefs_setattr,
 	.getattr = orangefs_getattr,

fs/overlayfs/inode.c

@@ -296,7 +296,6 @@ static const struct inode_operations ovl_file_inode_operations = {
 static const struct inode_operations ovl_symlink_inode_operations = {
 	.setattr	= ovl_setattr,
 	.get_link	= ovl_get_link,
-	.readlink	= generic_readlink,
 	.getattr	= ovl_getattr,
 	.listxattr	= ovl_listxattr,
 	.update_time	= ovl_update_time,

fs/proc/inode.c

@@ -425,7 +425,6 @@ static const char *proc_get_link(struct dentry *dentry,
 }
 
 const struct inode_operations proc_link_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= proc_get_link,
 };
 

fs/proc/self.c

@@ -6,18 +6,6 @@
 /*
  * /proc/self:
  */
-static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
-			      int buflen)
-{
-	struct pid_namespace *ns = dentry->d_sb->s_fs_info;
-	pid_t tgid = task_tgid_nr_ns(current, ns);
-	char tmp[PROC_NUMBUF];
-	if (!tgid)
-		return -ENOENT;
-	sprintf(tmp, "%d", tgid);
-	return readlink_copy(buffer, buflen, tmp);
-}
-
 static const char *proc_self_get_link(struct dentry *dentry,
 				      struct inode *inode,
 				      struct delayed_call *done)
@@ -38,7 +26,6 @@ static const char *proc_self_get_link(struct dentry *dentry,
 }
 
 static const struct inode_operations proc_self_inode_operations = {
-	.readlink	= proc_self_readlink,
 	.get_link	= proc_self_get_link,
 };
 

fs/proc/thread_self.c

@@ -6,19 +6,6 @@
 /*
  * /proc/thread_self:
  */
-static int proc_thread_self_readlink(struct dentry *dentry, char __user *buffer,
-			      int buflen)
-{
-	struct pid_namespace *ns = dentry->d_sb->s_fs_info;
-	pid_t tgid = task_tgid_nr_ns(current, ns);
-	pid_t pid = task_pid_nr_ns(current, ns);
-	char tmp[PROC_NUMBUF + 6 + PROC_NUMBUF];
-	if (!pid)
-		return -ENOENT;
-	sprintf(tmp, "%d/task/%d", tgid, pid);
-	return readlink_copy(buffer, buflen, tmp);
-}
-
 static const char *proc_thread_self_get_link(struct dentry *dentry,
 					     struct inode *inode,
 					     struct delayed_call *done)
@@ -40,7 +27,6 @@ static const char *proc_thread_self_get_link(struct dentry *dentry,
 }
 
 static const struct inode_operations proc_thread_self_inode_operations = {
-	.readlink	= proc_thread_self_readlink,
 	.get_link	= proc_thread_self_get_link,
 };
 

fs/reiserfs/namei.c

@@ -1665,7 +1665,6 @@ const struct inode_operations reiserfs_dir_inode_operations = {
  * stuff added
  */
 const struct inode_operations reiserfs_symlink_inode_operations = {
-	.readlink = generic_readlink,
 	.get_link	= page_get_link,
 	.setattr = reiserfs_setattr,
 	.listxattr = reiserfs_listxattr,

fs/squashfs/symlink.c

@@ -118,7 +118,6 @@ const struct address_space_operations squashfs_symlink_aops = {
 };
 
 const struct inode_operations squashfs_symlink_inode_ops = {
-	.readlink = generic_readlink,
 	.get_link = page_get_link,
 	.listxattr = squashfs_listxattr
 };

fs/stat.c

@@ -329,12 +329,14 @@ retry:
 		struct inode *inode = d_backing_inode(path.dentry);
 
 		error = empty ? -ENOENT : -EINVAL;
-		if (inode->i_op->readlink) {
+		/*
+		 * AFS mountpoints allow readlink(2) but are not symlinks
+		 */
+		if (d_is_symlink(path.dentry) || inode->i_op->readlink) {
 			error = security_inode_readlink(path.dentry);
 			if (!error) {
 				touch_atime(&path);
-				error = inode->i_op->readlink(path.dentry,
-							      buf, bufsiz);
+				error = vfs_readlink(path.dentry, buf, bufsiz);
 			}
 		}
 		path_put(&path);

fs/sysv/inode.c

@@ -145,7 +145,6 @@ static inline void write3byte(struct sysv_sb_info *sbi,
 }
 
 static const struct inode_operations sysv_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
 	.getattr	= sysv_getattr,
 };

fs/ubifs/file.c

@@ -1733,7 +1733,6 @@ const struct inode_operations ubifs_file_inode_operations = {
 };
 
 const struct inode_operations ubifs_symlink_inode_operations = {
-	.readlink    = generic_readlink,
 	.get_link    = ubifs_get_link,
 	.setattr     = ubifs_setattr,
 	.getattr     = ubifs_getattr,

fs/xfs/xfs_ioctl.c

@@ -287,7 +287,7 @@ xfs_readlink_by_handle(
 		return PTR_ERR(dentry);
 
 	/* Restrict this handle operation to symlinks only. */
-	if (!d_inode(dentry)->i_op->readlink) {
+	if (!d_is_symlink(dentry)) {
 		error = -EINVAL;
 		goto out_dput;
 	}
@@ -297,7 +297,7 @@ xfs_readlink_by_handle(
 		goto out_dput;
 	}
 
-	error = d_inode(dentry)->i_op->readlink(dentry, hreq->ohandle, olen);
+	error = vfs_readlink(dentry, hreq->ohandle, olen);
 
  out_dput:
 	dput(dentry);

fs/xfs/xfs_iops.c

@@ -1120,7 +1120,6 @@ static const struct inode_operations xfs_dir_ci_inode_operations = {
 };
 
 static const struct inode_operations xfs_symlink_inode_operations = {
-	.readlink		= generic_readlink,
 	.get_link		= xfs_vn_get_link,
 	.getattr		= xfs_vn_getattr,
 	.setattr		= xfs_vn_setattr,
@@ -1129,7 +1128,6 @@ static const struct inode_operations xfs_symlink_inode_operations = {
 };
 
 static const struct inode_operations xfs_inline_symlink_inode_operations = {
-	.readlink		= generic_readlink,
 	.get_link		= xfs_vn_get_link_inline,
 	.getattr		= xfs_vn_getattr,
 	.setattr		= xfs_vn_setattr,

include/linux/fs.h

@@ -543,6 +543,7 @@ is_uncached_acl(struct posix_acl *acl)
 #define IOP_LOOKUP	0x0002
 #define IOP_NOFOLLOW	0x0004
 #define IOP_XATTR	0x0008
+#define IOP_DEFAULT_READLINK	0x0010
 
 /*
  * Keep mostly read-only and often accessed (especially for
@@ -2867,7 +2868,6 @@ extern int __page_symlink(struct inode *inode, const char *symname, int len,
 extern int page_symlink(struct inode *inode, const char *symname, int len);
 extern const struct inode_operations page_symlink_inode_operations;
 extern void kfree_link(void *);
-extern int generic_readlink(struct dentry *, char __user *, int);
 extern void generic_fillattr(struct inode *, struct kstat *);
 int vfs_getattr_nosec(struct path *path, struct kstat *stat);
 extern int vfs_getattr(struct path *, struct kstat *);
@@ -2888,6 +2888,7 @@ extern int vfs_lstat(const char __user *, struct kstat *);
 extern int vfs_fstat(unsigned int, struct kstat *);
 extern int vfs_fstatat(int , const char __user *, struct kstat *, int);
 extern const char *vfs_get_link(struct dentry *, struct delayed_call *);
+extern int vfs_readlink(struct dentry *, char __user *, int);
 
 extern int __generic_block_fiemap(struct inode *inode,
 				  struct fiemap_extent_info *fieinfo,

mm/shmem.c

@@ -3212,7 +3212,6 @@ static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
 #endif /* CONFIG_TMPFS_XATTR */
 
 static const struct inode_operations shmem_short_symlink_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= simple_get_link,
 #ifdef CONFIG_TMPFS_XATTR
 	.listxattr	= shmem_listxattr,
@@ -3220,7 +3219,6 @@ static const struct inode_operations shmem_short_symlink_operations = {
 };
 
 static const struct inode_operations shmem_symlink_inode_operations = {
-	.readlink	= generic_readlink,
 	.get_link	= shmem_get_link,
 #ifdef CONFIG_TMPFS_XATTR
 	.listxattr	= shmem_listxattr,