Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

7 files changed, 777 insertions, 0 deletions

diff --git a/fs/qnx4/Kconfig b/fs/qnx4/Kconfig
new file mode 100644
index 0000000000..a2eb826e76
--- /dev/null
+++ b/fs/qnx4/Kconfig
@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config QNX4FS_FS
+	tristate "QNX4 file system support (read only)"
+	depends on BLOCK
+	select BUFFER_HEAD
+	help
+	  This is the file system used by the real-time operating systems
+	  QNX 4 and QNX 6 (the latter is also called QNX RTP).
+	  Further information is available at <http://www.qnx.com/>.
+	  Say Y if you intend to mount QNX hard disks or floppies.
+
+	  To compile this file system support as a module, choose M here: the
+	  module will be called qnx4.
+
+	  If you don't know whether you need it, then you don't need it:
+	  answer N.
diff --git a/fs/qnx4/Makefile b/fs/qnx4/Makefile
new file mode 100644
index 0000000000..42d4fc263a
--- /dev/null
+++ b/fs/qnx4/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for the linux qnx4-filesystem routines.
+#
+
+obj-$(CONFIG_QNX4FS_FS) += qnx4.o
+
+qnx4-objs := inode.o dir.o namei.o bitmap.o
diff --git a/fs/qnx4/bitmap.c b/fs/qnx4/bitmap.c
new file mode 100644
index 0000000000..163afc4ba4
--- /dev/null
+++ b/fs/qnx4/bitmap.c
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * QNX4 file system, Linux implementation.
+ *
+ * Version : 0.2.1
+ *
+ * Using parts of the xiafs filesystem.
+ *
+ * History :
+ *
+ * 28-05-1998 by Richard Frowijn : first release.
+ * 20-06-1998 by Frank Denis : basic optimisations.
+ * 25-06-1998 by Frank Denis : qnx4_is_free, qnx4_set_bitmap, qnx4_bmap .
+ * 28-06-1998 by Frank Denis : qnx4_free_inode (to be fixed) .
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/bitops.h>
+#include "qnx4.h"
+
+unsigned long qnx4_count_free_blocks(struct super_block *sb)
+{
+	int start = le32_to_cpu(qnx4_sb(sb)->BitMap->di_first_xtnt.xtnt_blk) - 1;
+	int total = 0;
+	int total_free = 0;
+	int offset = 0;
+	int size = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size);
+	struct buffer_head *bh;
+
+	while (total < size) {
+		int bytes = min(size - total, QNX4_BLOCK_SIZE);
+
+		if ((bh = sb_bread(sb, start + offset)) == NULL) {
+			printk(KERN_ERR "qnx4: I/O error in counting free blocks\n");
+			break;
+		}
+		total_free += bytes * BITS_PER_BYTE -
+				memweight(bh->b_data, bytes);
+		brelse(bh);
+		total += bytes;
+		offset++;
+	}
+
+	return total_free;
+}
diff --git a/fs/qnx4/dir.c b/fs/qnx4/dir.c
new file mode 100644
index 0000000000..66645a5a35
--- /dev/null
+++ b/fs/qnx4/dir.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * QNX4 file system, Linux implementation.
+ *
+ * Version : 0.2.1
+ *
+ * Using parts of the xiafs filesystem.
+ *
+ * History :
+ *
+ * 28-05-1998 by Richard Frowijn : first release.
+ * 20-06-1998 by Frank Denis : Linux 2.1.99+ & dcache support.
+ */
+
+#include <linux/buffer_head.h>
+#include "qnx4.h"
+
+/*
+ * A qnx4 directory entry is an inode entry or link info
+ * depending on the status field in the last byte. The
+ * first byte is where the name start either way, and a
+ * zero means it's empty.
+ *
+ * Also, due to a bug in gcc, we don't want to use the
+ * real (differently sized) name arrays in the inode and
+ * link entries, but always the 'de_name[]' one in the
+ * fake struct entry.
+ *
+ * See
+ *
+ *   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578#c6
+ *
+ * for details, but basically gcc will take the size of the
+ * 'name' array from one of the used union entries randomly.
+ *
+ * This use of 'de_name[]' (48 bytes) avoids the false positive
+ * warnings that would happen if gcc decides to use 'inode.di_name'
+ * (16 bytes) even when the pointer and size were to come from
+ * 'link.dl_name' (48 bytes).
+ *
+ * In all cases the actual name pointer itself is the same, it's
+ * only the gcc internal 'what is the size of this field' logic
+ * that can get confused.
+ */
+union qnx4_directory_entry {
+	struct {
+		const char de_name[48];
+		u8 de_pad[15];
+		u8 de_status;
+	};
+	struct qnx4_inode_entry inode;
+	struct qnx4_link_info link;
+};
+
+static int qnx4_readdir(struct file *file, struct dir_context *ctx)
+{
+	struct inode *inode = file_inode(file);
+	unsigned int offset;
+	struct buffer_head *bh;
+	unsigned long blknum;
+	int ix, ino;
+	int size;
+
+	QNX4DEBUG((KERN_INFO "qnx4_readdir:i_size = %ld\n", (long) inode->i_size));
+	QNX4DEBUG((KERN_INFO "pos                 = %ld\n", (long) ctx->pos));
+
+	while (ctx->pos < inode->i_size) {
+		blknum = qnx4_block_map(inode, ctx->pos >> QNX4_BLOCK_SIZE_BITS);
+		bh = sb_bread(inode->i_sb, blknum);
+		if (bh == NULL) {
+			printk(KERN_ERR "qnx4_readdir: bread failed (%ld)\n", blknum);
+			return 0;
+		}
+		ix = (ctx->pos >> QNX4_DIR_ENTRY_SIZE_BITS) % QNX4_INODES_PER_BLOCK;
+		for (; ix < QNX4_INODES_PER_BLOCK; ix++, ctx->pos += QNX4_DIR_ENTRY_SIZE) {
+			union qnx4_directory_entry *de;
+
+			offset = ix * QNX4_DIR_ENTRY_SIZE;
+			de = (union qnx4_directory_entry *) (bh->b_data + offset);
+
+			if (!de->de_name[0])
+				continue;
+			if (!(de->de_status & (QNX4_FILE_USED|QNX4_FILE_LINK)))
+				continue;
+			if (!(de->de_status & QNX4_FILE_LINK)) {
+				size = sizeof(de->inode.di_fname);
+				ino = blknum * QNX4_INODES_PER_BLOCK + ix - 1;
+			} else {
+				size = sizeof(de->link.dl_fname);
+				ino = ( le32_to_cpu(de->link.dl_inode_blk) - 1 ) *
+					QNX4_INODES_PER_BLOCK +
+					de->link.dl_inode_ndx;
+			}
+			size = strnlen(de->de_name, size);
+			QNX4DEBUG((KERN_INFO "qnx4_readdir:%.*s\n", size, name));
+			if (!dir_emit(ctx, de->de_name, size, ino, DT_UNKNOWN)) {
+				brelse(bh);
+				return 0;
+			}
+		}
+		brelse(bh);
+	}
+	return 0;
+}
+
+const struct file_operations qnx4_dir_operations =
+{
+	.llseek		= generic_file_llseek,
+	.read		= generic_read_dir,
+	.iterate_shared	= qnx4_readdir,
+	.fsync		= generic_file_fsync,
+};
+
+const struct inode_operations qnx4_dir_inode_operations =
+{
+	.lookup		= qnx4_lookup,
+};
diff --git a/fs/qnx4/inode.c b/fs/qnx4/inode.c
new file mode 100644
index 0000000000..a7171f5532
--- /dev/null
+++ b/fs/qnx4/inode.c
@@ -0,0 +1,423 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * QNX4 file system, Linux implementation.
+ *
+ * Version : 0.2.1
+ *
+ * Using parts of the xiafs filesystem.
+ *
+ * History :
+ *
+ * 01-06-1998 by Richard Frowijn : first release.
+ * 20-06-1998 by Frank Denis : Linux 2.1.99+ support, boot signature, misc.
+ * 30-06-1998 by Frank Denis : first step to write inodes.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/highuid.h>
+#include <linux/pagemap.h>
+#include <linux/buffer_head.h>
+#include <linux/writeback.h>
+#include <linux/statfs.h>
+#include "qnx4.h"
+
+#define QNX4_VERSION  4
+#define QNX4_BMNAME   ".bitmap"
+
+static const struct super_operations qnx4_sops;
+
+static struct inode *qnx4_alloc_inode(struct super_block *sb);
+static void qnx4_free_inode(struct inode *inode);
+static int qnx4_remount(struct super_block *sb, int *flags, char *data);
+static int qnx4_statfs(struct dentry *, struct kstatfs *);
+
+static const struct super_operations qnx4_sops =
+{
+	.alloc_inode	= qnx4_alloc_inode,
+	.free_inode	= qnx4_free_inode,
+	.statfs		= qnx4_statfs,
+	.remount_fs	= qnx4_remount,
+};
+
+static int qnx4_remount(struct super_block *sb, int *flags, char *data)
+{
+	struct qnx4_sb_info *qs;
+
+	sync_filesystem(sb);
+	qs = qnx4_sb(sb);
+	qs->Version = QNX4_VERSION;
+	*flags |= SB_RDONLY;
+	return 0;
+}
+
+static int qnx4_get_block( struct inode *inode, sector_t iblock, struct buffer_head *bh, int create )
+{
+	unsigned long phys;
+
+	QNX4DEBUG((KERN_INFO "qnx4: qnx4_get_block inode=[%ld] iblock=[%ld]\n",inode->i_ino,iblock));
+
+	phys = qnx4_block_map( inode, iblock );
+	if ( phys ) {
+		// logical block is before EOF
+		map_bh(bh, inode->i_sb, phys);
+	}
+	return 0;
+}
+
+static inline u32 try_extent(qnx4_xtnt_t *extent, u32 *offset)
+{
+	u32 size = le32_to_cpu(extent->xtnt_size);
+	if (*offset < size)
+		return le32_to_cpu(extent->xtnt_blk) + *offset - 1;
+	*offset -= size;
+	return 0;
+}
+
+unsigned long qnx4_block_map( struct inode *inode, long iblock )
+{
+	int ix;
+	long i_xblk;
+	struct buffer_head *bh = NULL;
+	struct qnx4_xblk *xblk = NULL;
+	struct qnx4_inode_entry *qnx4_inode = qnx4_raw_inode(inode);
+	u16 nxtnt = le16_to_cpu(qnx4_inode->di_num_xtnts);
+	u32 offset = iblock;
+	u32 block = try_extent(&qnx4_inode->di_first_xtnt, &offset);
+
+	if (block) {
+		// iblock is in the first extent. This is easy.
+	} else {
+		// iblock is beyond first extent. We have to follow the extent chain.
+		i_xblk = le32_to_cpu(qnx4_inode->di_xblk);
+		ix = 0;
+		while ( --nxtnt > 0 ) {
+			if ( ix == 0 ) {
+				// read next xtnt block.
+				bh = sb_bread(inode->i_sb, i_xblk - 1);
+				if ( !bh ) {
+					QNX4DEBUG((KERN_ERR "qnx4: I/O error reading xtnt block [%ld])\n", i_xblk - 1));
+					return -EIO;
+				}
+				xblk = (struct qnx4_xblk*)bh->b_data;
+				if ( memcmp( xblk->xblk_signature, "IamXblk", 7 ) ) {
+					QNX4DEBUG((KERN_ERR "qnx4: block at %ld is not a valid xtnt\n", qnx4_inode->i_xblk));
+					return -EIO;
+				}
+			}
+			block = try_extent(&xblk->xblk_xtnts[ix], &offset);
+			if (block) {
+				// got it!
+				break;
+			}
+			if ( ++ix >= xblk->xblk_num_xtnts ) {
+				i_xblk = le32_to_cpu(xblk->xblk_next_xblk);
+				ix = 0;
+				brelse( bh );
+				bh = NULL;
+			}
+		}
+		if ( bh )
+			brelse( bh );
+	}
+
+	QNX4DEBUG((KERN_INFO "qnx4: mapping block %ld of inode %ld = %ld\n",iblock,inode->i_ino,block));
+	return block;
+}
+
+static int qnx4_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	struct super_block *sb = dentry->d_sb;
+	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
+
+	buf->f_type    = sb->s_magic;
+	buf->f_bsize   = sb->s_blocksize;
+	buf->f_blocks  = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size) * 8;
+	buf->f_bfree   = qnx4_count_free_blocks(sb);
+	buf->f_bavail  = buf->f_bfree;
+	buf->f_namelen = QNX4_NAME_MAX;
+	buf->f_fsid    = u64_to_fsid(id);
+
+	return 0;
+}
+
+/*
+ * Check the root directory of the filesystem to make sure
+ * it really _is_ a qnx4 filesystem, and to check the size
+ * of the directory entry.
+ */
+static const char *qnx4_checkroot(struct super_block *sb,
+				  struct qnx4_super_block *s)
+{
+	struct buffer_head *bh;
+	struct qnx4_inode_entry *rootdir;
+	int rd, rl;
+	int i, j;
+
+	if (s->RootDir.di_fname[0] != '/' || s->RootDir.di_fname[1] != '\0')
+		return "no qnx4 filesystem (no root dir).";
+	QNX4DEBUG((KERN_NOTICE "QNX4 filesystem found on dev %s.\n", sb->s_id));
+	rd = le32_to_cpu(s->RootDir.di_first_xtnt.xtnt_blk) - 1;
+	rl = le32_to_cpu(s->RootDir.di_first_xtnt.xtnt_size);
+	for (j = 0; j < rl; j++) {
+		bh = sb_bread(sb, rd + j);	/* root dir, first block */
+		if (bh == NULL)
+			return "unable to read root entry.";
+		rootdir = (struct qnx4_inode_entry *) bh->b_data;
+		for (i = 0; i < QNX4_INODES_PER_BLOCK; i++, rootdir++) {
+			QNX4DEBUG((KERN_INFO "rootdir entry found : [%s]\n", rootdir->di_fname));
+			if (strcmp(rootdir->di_fname, QNX4_BMNAME) != 0)
+				continue;
+			qnx4_sb(sb)->BitMap = kmemdup(rootdir,
+						      sizeof(struct qnx4_inode_entry),
+						      GFP_KERNEL);
+			brelse(bh);
+			if (!qnx4_sb(sb)->BitMap)
+				return "not enough memory for bitmap inode";
+			/* keep bitmap inode known */
+			return NULL;
+		}
+		brelse(bh);
+	}
+	return "bitmap file not found.";
+}
+
+static int qnx4_fill_super(struct super_block *s, void *data, int silent)
+{
+	struct buffer_head *bh;
+	struct inode *root;
+	const char *errmsg;
+	struct qnx4_sb_info *qs;
+
+	qs = kzalloc(sizeof(struct qnx4_sb_info), GFP_KERNEL);
+	if (!qs)
+		return -ENOMEM;
+	s->s_fs_info = qs;
+
+	sb_set_blocksize(s, QNX4_BLOCK_SIZE);
+
+	s->s_op = &qnx4_sops;
+	s->s_magic = QNX4_SUPER_MAGIC;
+	s->s_flags |= SB_RDONLY;	/* Yup, read-only yet */
+	s->s_time_min = 0;
+	s->s_time_max = U32_MAX;
+
+	/* Check the superblock signature. Since the qnx4 code is
+	   dangerous, we should leave as quickly as possible
+	   if we don't belong here... */
+	bh = sb_bread(s, 1);
+	if (!bh) {
+		printk(KERN_ERR "qnx4: unable to read the superblock\n");
+		return -EINVAL;
+	}
+
+ 	/* check before allocating dentries, inodes, .. */
+	errmsg = qnx4_checkroot(s, (struct qnx4_super_block *) bh->b_data);
+	brelse(bh);
+	if (errmsg != NULL) {
+ 		if (!silent)
+			printk(KERN_ERR "qnx4: %s\n", errmsg);
+		return -EINVAL;
+	}
+
+ 	/* does root not have inode number QNX4_ROOT_INO ?? */
+	root = qnx4_iget(s, QNX4_ROOT_INO * QNX4_INODES_PER_BLOCK);
+	if (IS_ERR(root)) {
+		printk(KERN_ERR "qnx4: get inode failed\n");
+		return PTR_ERR(root);
+ 	}
+
+ 	s->s_root = d_make_root(root);
+ 	if (s->s_root == NULL)
+ 		return -ENOMEM;
+
+	return 0;
+}
+
+static void qnx4_kill_sb(struct super_block *sb)
+{
+	struct qnx4_sb_info *qs = qnx4_sb(sb);
+	kill_block_super(sb);
+	if (qs) {
+		kfree(qs->BitMap);
+		kfree(qs);
+	}
+}
+
+static int qnx4_read_folio(struct file *file, struct folio *folio)
+{
+	return block_read_full_folio(folio, qnx4_get_block);
+}
+
+static sector_t qnx4_bmap(struct address_space *mapping, sector_t block)
+{
+	return generic_block_bmap(mapping,block,qnx4_get_block);
+}
+
+static const struct address_space_operations qnx4_aops = {
+	.read_folio	= qnx4_read_folio,
+	.bmap		= qnx4_bmap
+};
+
+struct inode *qnx4_iget(struct super_block *sb, unsigned long ino)
+{
+	struct buffer_head *bh;
+	struct qnx4_inode_entry *raw_inode;
+	int block;
+	struct qnx4_inode_entry *qnx4_inode;
+	struct inode *inode;
+
+	inode = iget_locked(sb, ino);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+	if (!(inode->i_state & I_NEW))
+		return inode;
+
+	qnx4_inode = qnx4_raw_inode(inode);
+	inode->i_mode = 0;
+
+	QNX4DEBUG((KERN_INFO "reading inode : [%d]\n", ino));
+	if (!ino) {
+		printk(KERN_ERR "qnx4: bad inode number on dev %s: %lu is "
+				"out of range\n",
+		       sb->s_id, ino);
+		iget_failed(inode);
+		return ERR_PTR(-EIO);
+	}
+	block = ino / QNX4_INODES_PER_BLOCK;
+
+	if (!(bh = sb_bread(sb, block))) {
+		printk(KERN_ERR "qnx4: major problem: unable to read inode from dev "
+		       "%s\n", sb->s_id);
+		iget_failed(inode);
+		return ERR_PTR(-EIO);
+	}
+	raw_inode = ((struct qnx4_inode_entry *) bh->b_data) +
+	    (ino % QNX4_INODES_PER_BLOCK);
+
+	inode->i_mode    = le16_to_cpu(raw_inode->di_mode);
+	i_uid_write(inode, (uid_t)le16_to_cpu(raw_inode->di_uid));
+	i_gid_write(inode, (gid_t)le16_to_cpu(raw_inode->di_gid));
+	set_nlink(inode, le16_to_cpu(raw_inode->di_nlink));
+	inode->i_size    = le32_to_cpu(raw_inode->di_size);
+	inode->i_mtime.tv_sec   = le32_to_cpu(raw_inode->di_mtime);
+	inode->i_mtime.tv_nsec = 0;
+	inode->i_atime.tv_sec   = le32_to_cpu(raw_inode->di_atime);
+	inode->i_atime.tv_nsec = 0;
+	inode_set_ctime(inode, le32_to_cpu(raw_inode->di_ctime), 0);
+	inode->i_blocks  = le32_to_cpu(raw_inode->di_first_xtnt.xtnt_size);
+
+	memcpy(qnx4_inode, raw_inode, QNX4_DIR_ENTRY_SIZE);
+	if (S_ISREG(inode->i_mode)) {
+		inode->i_fop = &generic_ro_fops;
+		inode->i_mapping->a_ops = &qnx4_aops;
+		qnx4_i(inode)->mmu_private = inode->i_size;
+	} else if (S_ISDIR(inode->i_mode)) {
+		inode->i_op = &qnx4_dir_inode_operations;
+		inode->i_fop = &qnx4_dir_operations;
+	} else if (S_ISLNK(inode->i_mode)) {
+		inode->i_op = &page_symlink_inode_operations;
+		inode_nohighmem(inode);
+		inode->i_mapping->a_ops = &qnx4_aops;
+		qnx4_i(inode)->mmu_private = inode->i_size;
+	} else {
+		printk(KERN_ERR "qnx4: bad inode %lu on dev %s\n",
+			ino, sb->s_id);
+		iget_failed(inode);
+		brelse(bh);
+		return ERR_PTR(-EIO);
+	}
+	brelse(bh);
+	unlock_new_inode(inode);
+	return inode;
+}
+
+static struct kmem_cache *qnx4_inode_cachep;
+
+static struct inode *qnx4_alloc_inode(struct super_block *sb)
+{
+	struct qnx4_inode_info *ei;
+	ei = alloc_inode_sb(sb, qnx4_inode_cachep, GFP_KERNEL);
+	if (!ei)
+		return NULL;
+	return &ei->vfs_inode;
+}
+
+static void qnx4_free_inode(struct inode *inode)
+{
+	kmem_cache_free(qnx4_inode_cachep, qnx4_i(inode));
+}
+
+static void init_once(void *foo)
+{
+	struct qnx4_inode_info *ei = (struct qnx4_inode_info *) foo;
+
+	inode_init_once(&ei->vfs_inode);
+}
+
+static int init_inodecache(void)
+{
+	qnx4_inode_cachep = kmem_cache_create("qnx4_inode_cache",
+					     sizeof(struct qnx4_inode_info),
+					     0, (SLAB_RECLAIM_ACCOUNT|
+						SLAB_MEM_SPREAD|SLAB_ACCOUNT),
+					     init_once);
+	if (qnx4_inode_cachep == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+static void destroy_inodecache(void)
+{
+	/*
+	 * Make sure all delayed rcu free inodes are flushed before we
+	 * destroy cache.
+	 */
+	rcu_barrier();
+	kmem_cache_destroy(qnx4_inode_cachep);
+}
+
+static struct dentry *qnx4_mount(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data)
+{
+	return mount_bdev(fs_type, flags, dev_name, data, qnx4_fill_super);
+}
+
+static struct file_system_type qnx4_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "qnx4",
+	.mount		= qnx4_mount,
+	.kill_sb	= qnx4_kill_sb,
+	.fs_flags	= FS_REQUIRES_DEV,
+};
+MODULE_ALIAS_FS("qnx4");
+
+static int __init init_qnx4_fs(void)
+{
+	int err;
+
+	err = init_inodecache();
+	if (err)
+		return err;
+
+	err = register_filesystem(&qnx4_fs_type);
+	if (err) {
+		destroy_inodecache();
+		return err;
+	}
+
+	printk(KERN_INFO "QNX4 filesystem 0.2.3 registered.\n");
+	return 0;
+}
+
+static void __exit exit_qnx4_fs(void)
+{
+	unregister_filesystem(&qnx4_fs_type);
+	destroy_inodecache();
+}
+
+module_init(init_qnx4_fs)
+module_exit(exit_qnx4_fs)
+MODULE_LICENSE("GPL");
+
diff --git a/fs/qnx4/namei.c b/fs/qnx4/namei.c
new file mode 100644
index 0000000000..8d72221735
--- /dev/null
+++ b/fs/qnx4/namei.c
@@ -0,0 +1,122 @@
+// SPDX-License-Identifier: GPL-2.0
+/* 
+ * QNX4 file system, Linux implementation.
+ * 
+ * Version : 0.2.1
+ * 
+ * Using parts of the xiafs filesystem.
+ * 
+ * History :
+ * 
+ * 01-06-1998 by Richard Frowijn : first release.
+ * 21-06-1998 by Frank Denis : dcache support, fixed error codes.
+ * 04-07-1998 by Frank Denis : first step for rmdir/unlink.
+ */
+
+#include <linux/buffer_head.h>
+#include "qnx4.h"
+
+
+/*
+ * check if the filename is correct. For some obscure reason, qnx writes a
+ * new file twice in the directory entry, first with all possible options at 0
+ * and for a second time the way it is, they want us not to access the qnx
+ * filesystem when whe are using linux.
+ */
+static int qnx4_match(int len, const char *name,
+		      struct buffer_head *bh, unsigned long *offset)
+{
+	struct qnx4_inode_entry *de;
+	int namelen, thislen;
+
+	if (bh == NULL) {
+		printk(KERN_WARNING "qnx4: matching unassigned buffer !\n");
+		return 0;
+	}
+	de = (struct qnx4_inode_entry *) (bh->b_data + *offset);
+	*offset += QNX4_DIR_ENTRY_SIZE;
+	if ((de->di_status & QNX4_FILE_LINK) != 0) {
+		namelen = QNX4_NAME_MAX;
+	} else {
+		namelen = QNX4_SHORT_NAME_MAX;
+	}
+	thislen = strlen( de->di_fname );
+	if ( thislen > namelen )
+		thislen = namelen;
+	if (len != thislen) {
+		return 0;
+	}
+	if (strncmp(name, de->di_fname, len) == 0) {
+		if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) != 0) {
+			return 1;
+		}
+	}
+	return 0;
+}
+
+static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
+	   const char *name, struct qnx4_inode_entry **res_dir, int *ino)
+{
+	unsigned long block, offset, blkofs;
+	struct buffer_head *bh;
+
+	*res_dir = NULL;
+	bh = NULL;
+	block = offset = blkofs = 0;
+	while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
+		if (!bh) {
+			block = qnx4_block_map(dir, blkofs);
+			if (block)
+				bh = sb_bread(dir->i_sb, block);
+			if (!bh) {
+				blkofs++;
+				continue;
+			}
+		}
+		*res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
+		if (qnx4_match(len, name, bh, &offset)) {
+			*ino = block * QNX4_INODES_PER_BLOCK +
+			    (offset / QNX4_DIR_ENTRY_SIZE) - 1;
+			return bh;
+		}
+		if (offset < bh->b_size) {
+			continue;
+		}
+		brelse(bh);
+		bh = NULL;
+		offset = 0;
+		blkofs++;
+	}
+	brelse(bh);
+	*res_dir = NULL;
+	return NULL;
+}
+
+struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
+{
+	int ino;
+	struct qnx4_inode_entry *de;
+	struct qnx4_link_info *lnk;
+	struct buffer_head *bh;
+	const char *name = dentry->d_name.name;
+	int len = dentry->d_name.len;
+	struct inode *foundinode = NULL;
+
+	if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))
+		goto out;
+	/* The entry is linked, let's get the real info */
+	if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {
+		lnk = (struct qnx4_link_info *) de;
+		ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) *
+                    QNX4_INODES_PER_BLOCK +
+		    lnk->dl_inode_ndx;
+	}
+	brelse(bh);
+
+	foundinode = qnx4_iget(dir->i_sb, ino);
+	if (IS_ERR(foundinode))
+		QNX4DEBUG((KERN_ERR "qnx4: lookup->iget -> error %ld\n",
+			   PTR_ERR(foundinode)));
+out:
+	return d_splice_alias(foundinode, dentry);
+}
diff --git a/fs/qnx4/qnx4.h b/fs/qnx4/qnx4.h
new file mode 100644
index 0000000000..6283705466
--- /dev/null
+++ b/fs/qnx4/qnx4.h
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/fs.h>
+#include <linux/qnx4_fs.h>
+
+#define QNX4_DEBUG 0
+
+#if QNX4_DEBUG
+#define QNX4DEBUG(X) printk X
+#else
+#define QNX4DEBUG(X) (void) 0
+#endif
+
+struct qnx4_sb_info {
+	unsigned int		Version;	/* may be useful */
+	struct qnx4_inode_entry	*BitMap;	/* useful */
+};
+
+struct qnx4_inode_info {
+	struct qnx4_inode_entry raw;
+	loff_t mmu_private;
+	struct inode vfs_inode;
+};
+
+extern struct inode *qnx4_iget(struct super_block *, unsigned long);
+extern struct dentry *qnx4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags);
+extern unsigned long qnx4_count_free_blocks(struct super_block *sb);
+extern unsigned long qnx4_block_map(struct inode *inode, long iblock);
+
+extern const struct inode_operations qnx4_dir_inode_operations;
+extern const struct file_operations qnx4_dir_operations;
+extern int qnx4_is_free(struct super_block *sb, long block);
+
+static inline struct qnx4_sb_info *qnx4_sb(struct super_block *sb)
+{
+	return sb->s_fs_info;
+}
+
+static inline struct qnx4_inode_info *qnx4_i(struct inode *inode)
+{
+	return container_of(inode, struct qnx4_inode_info, vfs_inode);
+}
+
+static inline struct qnx4_inode_entry *qnx4_raw_inode(struct inode *inode)
+{
+	return &qnx4_i(inode)->raw;
+}