VFS: (Scripted) Convert S_ISLNK/DIR/REG(dentry->d_inode) to d_is_*(dentry)

Convert the following where appropriate:

 (1) S_ISLNK(dentry->d_inode) to d_is_symlink(dentry).

 (2) S_ISREG(dentry->d_inode) to d_is_reg(dentry).

 (3) S_ISDIR(dentry->d_inode) to d_is_dir(dentry).  This is actually more
     complicated than it appears as some calls should be converted to
     d_can_lookup() instead.  The difference is whether the directory in
     question is a real dir with a ->lookup op or whether it's a fake dir with
     a ->d_automount op.

In some circumstances, we can subsume checks for dentry->d_inode not being
NULL into this, provided we the code isn't in a filesystem that expects
d_inode to be NULL if the dirent really *is* negative (ie. if we're going to
use d_inode() rather than d_backing_inode() to get the inode pointer).

Note that the dentry type field may be set to something other than
DCACHE_MISS_TYPE when d_inode is NULL in the case of unionmount, where the VFS
manages the fall-through from a negative dentry to a lower layer.  In such a
case, the dentry type of the negative union dentry is set to the same as the
type of the lower dentry.

However, if you know d_inode is not NULL at the call site, then you can use
the d_is_xxx() functions even in a filesystem.

There is one further complication: a 0,0 chardev dentry may be labelled
DCACHE_WHITEOUT_TYPE rather than DCACHE_SPECIAL_TYPE.  Strictly, this was
intended for special directory entry types that don't have attached inodes.

The following perl+coccinelle script was used:

use strict;

my @callers;
open($fd, 'git grep -l \'S_IS[A-Z].*->d_inode\' |') ||
    die "Can't grep for S_ISDIR and co. callers";
@callers = <$fd>;
close($fd);
unless (@callers) {
    print "No matches\n";
    exit(0);
}

my @cocci = (
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISLNK(E->d_inode->i_mode)',
    '+ d_is_symlink(E)',
    '',
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISDIR(E->d_inode->i_mode)',
    '+ d_is_dir(E)',
    '',
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISREG(E->d_inode->i_mode)',
    '+ d_is_reg(E)' );

my $coccifile = "tmp.sp.cocci";
open($fd, ">$coccifile") || die $coccifile;
print($fd "$_\n") || die $coccifile foreach (@cocci);
close($fd);

foreach my $file (@callers) {
    chomp $file;
    print "Processing ", $file, "\n";
    system("spatch", "--sp-file", $coccifile, $file, "--in-place", "--no-show-diff") == 0 ||
	die "spatch failed";
}

[AV: overlayfs parts skipped]

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 3 insertions, 3 deletions

diff --git a/security/inode.c b/security/inode.c
index 8e7ca62..131a3c4 100644
--- a/security/inode.c
+++ b/security/inode.c
@@ -203,7 +203,7 @@ void securityfs_remove(struct dentry *dentry)
 	mutex_lock(&parent->d_inode->i_mutex);
 	if (positive(dentry)) {
 		if (dentry->d_inode) {
-			if (S_ISDIR(dentry->d_inode->i_mode))
+			if (d_is_dir(dentry))
 				simple_rmdir(parent->d_inode, dentry);
 			else
 				simple_unlink(parent->d_inode, dentry);
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 79f2c2c..4d1a541 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1799,7 +1799,7 @@ static inline int may_rename(struct inode *old_dir,
 
 	old_dsec = old_dir->i_security;
 	old_isec = old_dentry->d_inode->i_security;
-	old_is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
+	old_is_dir = d_is_dir(old_dentry);
 	new_dsec = new_dir->i_security;
 
 	ad.type = LSM_AUDIT_DATA_DENTRY;
@@ -1829,7 +1829,7 @@ static inline int may_rename(struct inode *old_dir,
 		return rc;
 	if (d_is_positive(new_dentry)) {
 		new_isec = new_dentry->d_inode->i_security;
-		new_is_dir = S_ISDIR(new_dentry->d_inode->i_mode);
+		new_is_dir = d_is_dir(new_dentry);
 		rc = avc_has_perm(sid, new_isec->sid,
 				  new_isec->sclass,
 				  (new_is_dir ? DIR__RMDIR : FILE__UNLINK), &ad);