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/fs/autofs4/expire.c b/fs/autofs4/expire.c
index bfdbaba..11dd118 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -374,7 +374,7 @@ static struct dentry *should_expire(struct dentry *dentry,
 		return NULL;
 	}
 
-	if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)) {
+	if (dentry->d_inode && d_is_symlink(dentry)) {
 		DPRINTK("checking symlink %p %pd", dentry, dentry);
 		/*
 		 * A symlink can't be "busy" in the usual sense so
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index 7ba355b..7e44fdd 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -371,7 +371,7 @@ static struct vfsmount *autofs4_d_automount(struct path *path)
 	 * having d_mountpoint() true, so there's no need to call back
 	 * to the daemon.
 	 */
-	if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)) {
+	if (dentry->d_inode && d_is_symlink(dentry)) {
 		spin_unlock(&sbi->fs_lock);
 		goto done;
 	}
@@ -485,7 +485,7 @@ static int autofs4_d_manage(struct dentry *dentry, bool rcu_walk)
 		 * an incorrect ELOOP error return.
 		 */
 		if ((!d_mountpoint(dentry) && !simple_empty(dentry)) ||
-		    (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)))
+		    (dentry->d_inode && d_is_symlink(dentry)))
 			status = -EISDIR;
 	}
 	spin_unlock(&sbi->fs_lock);