ata: libata-scsi: fix ata_dsm_trim_pages() kernel-docgrafted

make htmldocs fails with:

  Documentation/driver-api/libata:604: ./drivers/ata/libata-scsi.c:2301:
  ERROR: Unexpected indentation. [docutils]

The Return: section of ata_dsm_trim_pages() ends its first sentence with
a colon and continues with an indented bullet list. reStructuredText
requires a blank line before an indented block, so docutils chokes on
the list.

Simply adding the missing blank line does not work either: Return: is a
kernel-doc "special section", which is terminated by the first blank
line, so the bullet list would end up in the Description section,
detached from the sentence introducing it.

Spell the two bounds out as prose instead, so that the Return: section
stays self-contained. Documentation-only change.

Fixes: e64e6b5dc867 ("ata: libata-scsi: scale DSM TRIM payload by MAX PAGES PER DSM COMMAND")
Reported-by: Thomas Huth <thuth@redhat.com>
Closes: https://lore.kernel.org/linux-ide/b0a0b8e8-cc4f-4c7b-8bc5-fee0712d405a@redhat.com/
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Link: https://lore.kernel.org/r/20260916130031.29990-2-cassel@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>

6 files changed, 1265 insertions, 0 deletions

diff --git a/fs/cramfs/Kconfig b/fs/cramfs/Kconfig
new file mode 100644
index 000000000..4612c9bbf
--- /dev/null
+++ b/fs/cramfs/Kconfig
@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config CRAMFS
+	tristate "Compressed ROM file system support (cramfs)"
+	select ZLIB_INFLATE
+	help
+	  Saying Y here includes support for CramFs (Compressed ROM File
+	  System).  CramFs is designed to be a simple, small, and compressed
+	  file system for ROM based embedded systems.  CramFs is read-only,
+	  limited to 256MB file systems (with 16MB files), and doesn't support
+	  16/32 bits uid/gid, hard links and timestamps.
+
+	  See <file:Documentation/filesystems/cramfs.rst> and
+	  <file:fs/cramfs/README> for further information.
+
+	  To compile this as a module, choose M here: the module will be called
+	  cramfs.  Note that the root file system (the one containing the
+	  directory /) cannot be compiled as a module.
+
+	  This filesystem is limited in capabilities and performance on
+	  purpose to remain small and low on RAM usage. It is most suitable
+	  for small embedded systems. If you have ample RAM to spare, you may
+	  consider a more capable compressed filesystem such as SquashFS
+	  which is much better in terms of performance and features.
+
+	  If unsure, say N.
+
+config CRAMFS_BLOCKDEV
+	bool "Support CramFs image over a regular block device" if EXPERT
+	depends on CRAMFS && BLOCK
+	default y
+	help
+	  This option allows the CramFs driver to load data from a regular
+	  block device such a disk partition or a ramdisk.
+
+config CRAMFS_MTD
+	bool "Support CramFs image directly mapped in physical memory"
+	depends on CRAMFS && CRAMFS <= MTD
+	default y if !CRAMFS_BLOCKDEV
+	help
+	  This option allows the CramFs driver to load data directly from
+	  a linear addressed memory range (usually non-volatile memory
+	  like flash) instead of going through the block device layer.
+	  This saves some memory since no intermediate buffering is
+	  necessary.
+
+	  The location of the CramFs image is determined by a
+	  MTD device capable of direct memory mapping e.g. from
+	  the 'physmap' map driver or a resulting MTD partition.
+	  For example, this would mount the cramfs image stored in
+	  the MTD partition named "xip_fs" on the /mnt mountpoint:
+
+	  mount -t cramfs mtd:xip_fs /mnt
+
+	  If unsure, say N.
diff --git a/fs/cramfs/Makefile b/fs/cramfs/Makefile
new file mode 100644
index 000000000..8c3ed2982
--- /dev/null
+++ b/fs/cramfs/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for the linux cramfs routines.
+#
+
+obj-$(CONFIG_CRAMFS) += cramfs.o
+
+cramfs-objs := inode.o uncompress.o
diff --git a/fs/cramfs/README b/fs/cramfs/README
new file mode 100644
index 000000000..c0052a11a
--- /dev/null
+++ b/fs/cramfs/README
@@ -0,0 +1,107 @@
+Notes on Filesystem Layout
+--------------------------
+
+These notes describe what mkcramfs generates.  Kernel requirements are
+a bit looser, e.g. it doesn't care if the <file_data> items are
+swapped around (though it does care that directory entries (inodes) in
+a given directory are contiguous, as this is used by readdir).
+
+All data is currently in host-endian format; neither mkcramfs nor the
+kernel ever do swabbing.  (See section `Block Size' below.)
+
+<filesystem>:
+	<superblock>
+	<directory_structure>
+	<data>
+
+<superblock>: struct cramfs_super (see cramfs_fs.h).
+
+<directory_structure>:
+	For each file:
+		struct cramfs_inode (see cramfs_fs.h).
+		Filename.  Not generally null-terminated, but it is
+		 null-padded to a multiple of 4 bytes.
+
+The order of inode traversal is described as "width-first" (not to be
+confused with breadth-first); i.e. like depth-first but listing all of
+a directory's entries before recursing down its subdirectories: the
+same order as `ls -AUR' (but without the /^\..*:$/ directory header
+lines); put another way, the same order as `find -type d -exec
+ls -AU1 {} \;'.
+
+Beginning in 2.4.7, directory entries are sorted.  This optimization
+allows cramfs_lookup to return more quickly when a filename does not
+exist, speeds up user-space directory sorts, etc.
+
+<data>:
+	One <file_data> for each file that's either a symlink or a
+	 regular file of non-zero st_size.
+
+<file_data>:
+	nblocks * <block_pointer>
+	 (where nblocks = (st_size - 1) / blksize + 1)
+	nblocks * <block>
+	padding to multiple of 4 bytes
+
+The i'th <block_pointer> for a file stores the byte offset of the
+*end* of the i'th <block> (i.e. one past the last byte, which is the
+same as the start of the (i+1)'th <block> if there is one).  The first
+<block> immediately follows the last <block_pointer> for the file.
+<block_pointer>s are each 32 bits long.
+
+When the CRAMFS_FLAG_EXT_BLOCK_POINTERS capability bit is set, each
+<block_pointer>'s top bits may contain special flags as follows:
+
+CRAMFS_BLK_FLAG_UNCOMPRESSED (bit 31):
+	The block data is not compressed and should be copied verbatim.
+
+CRAMFS_BLK_FLAG_DIRECT_PTR (bit 30):
+	The <block_pointer> stores the actual block start offset and not
+	its end, shifted right by 2 bits. The block must therefore be
+	aligned to a 4-byte boundary. The block size is either blksize
+	if CRAMFS_BLK_FLAG_UNCOMPRESSED is also specified, otherwise
+	the compressed data length is included in the first 2 bytes of
+	the block data. This is used to allow discontiguous data layout
+	and specific data block alignments e.g. for XIP applications.
+
+
+The order of <file_data>'s is a depth-first descent of the directory
+tree, i.e. the same order as `find -size +0 \( -type f -o -type l \)
+-print'.
+
+
+<block>: The i'th <block> is the output of zlib's compress function
+applied to the i'th blksize-sized chunk of the input data if the
+corresponding CRAMFS_BLK_FLAG_UNCOMPRESSED <block_ptr> bit is not set,
+otherwise it is the input data directly.
+(For the last <block> of the file, the input may of course be smaller.)
+Each <block> may be a different size.  (See <block_pointer> above.)
+
+<block>s are merely byte-aligned, not generally u32-aligned.
+
+When CRAMFS_BLK_FLAG_DIRECT_PTR is specified then the corresponding
+<block> may be located anywhere and not necessarily contiguous with
+the previous/next blocks. In that case it is minimally u32-aligned.
+If CRAMFS_BLK_FLAG_UNCOMPRESSED is also specified then the size is always
+blksize except for the last block which is limited by the file length.
+If CRAMFS_BLK_FLAG_DIRECT_PTR is set and CRAMFS_BLK_FLAG_UNCOMPRESSED
+is not set then the first 2 bytes of the block contains the size of the
+remaining block data as this cannot be determined from the placement of
+logically adjacent blocks.
+
+
+Holes
+-----
+
+This kernel supports cramfs holes (i.e. [efficient representation of]
+blocks in uncompressed data consisting entirely of NUL bytes), but by
+default mkcramfs doesn't test for & create holes, since cramfs in
+kernels up to at least 2.3.39 didn't support holes.  Run mkcramfs
+with -z if you want it to create files that can have holes in them.
+
+
+Tools
+-----
+
+The cramfs user-space tools, including mkcramfs and cramfsck, are
+located at <https://github.com/npitre/cramfs-tools>.
diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
new file mode 100644
index 000000000..d4cd03f4f
--- /dev/null
+++ b/fs/cramfs/inode.c
@@ -0,0 +1,1012 @@
+/*
+ * Compressed rom filesystem for Linux.
+ *
+ * Copyright (C) 1999 Linus Torvalds.
+ *
+ * This file is released under the GPL.
+ */
+
+/*
+ * These are the VFS interfaces to the compressed rom filesystem.
+ * The actual compression is based on zlib, see the other files.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/filelock.h>
+#include <linux/pagemap.h>
+#include <linux/ramfs.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/blkdev.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/super.h>
+#include <linux/fs_context.h>
+#include <linux/slab.h>
+#include <linux/vfs.h>
+#include <linux/mutex.h>
+#include <uapi/linux/cramfs_fs.h>
+#include <linux/uaccess.h>
+
+#include "internal.h"
+
+/*
+ * cramfs super-block data in memory
+ */
+struct cramfs_sb_info {
+	unsigned long magic;
+	unsigned long size;
+	unsigned long blocks;
+	unsigned long files;
+	unsigned long flags;
+	void *linear_virt_addr;
+	resource_size_t linear_phys_addr;
+	size_t mtd_point_size;
+};
+
+static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb)
+{
+	return sb->s_fs_info;
+}
+
+static const struct super_operations cramfs_ops;
+static const struct inode_operations cramfs_dir_inode_operations;
+static const struct file_operations cramfs_directory_operations;
+static const struct file_operations cramfs_physmem_fops;
+static const struct address_space_operations cramfs_aops;
+
+static DEFINE_MUTEX(read_mutex);
+
+
+/* These macros may change in future, to provide better st_ino semantics. */
+#define OFFSET(x)	((x)->i_ino)
+
+static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset)
+{
+	if (!cino->offset)
+		return offset + 1;
+	if (!cino->size)
+		return offset + 1;
+
+	/*
+	 * The file mode test fixes buggy mkcramfs implementations where
+	 * cramfs_inode->offset is set to a non zero value for entries
+	 * which did not contain data, like devices node and fifos.
+	 */
+	switch (cino->mode & S_IFMT) {
+	case S_IFREG:
+	case S_IFDIR:
+	case S_IFLNK:
+		return cino->offset << 2;
+	default:
+		break;
+	}
+	return offset + 1;
+}
+
+static struct inode *get_cramfs_inode(struct super_block *sb,
+	const struct cramfs_inode *cramfs_inode, unsigned int offset)
+{
+	struct inode *inode;
+	static struct timespec64 zerotime;
+
+	inode = iget_locked(sb, cramino(cramfs_inode, offset));
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+	if (!(inode_state_read_once(inode) & I_NEW))
+		return inode;
+
+	switch (cramfs_inode->mode & S_IFMT) {
+	case S_IFREG:
+		inode->i_fop = &generic_ro_fops;
+		inode->i_data.a_ops = &cramfs_aops;
+		if (IS_ENABLED(CONFIG_CRAMFS_MTD) &&
+		    CRAMFS_SB(sb)->flags & CRAMFS_FLAG_EXT_BLOCK_POINTERS &&
+		    CRAMFS_SB(sb)->linear_phys_addr)
+			inode->i_fop = &cramfs_physmem_fops;
+		break;
+	case S_IFDIR:
+		inode->i_op = &cramfs_dir_inode_operations;
+		inode->i_fop = &cramfs_directory_operations;
+		break;
+	case S_IFLNK:
+		inode->i_op = &page_symlink_inode_operations;
+		inode_nohighmem(inode);
+		inode->i_data.a_ops = &cramfs_aops;
+		break;
+	case S_IFCHR:
+	case S_IFBLK:
+	case S_IFIFO:
+	case S_IFSOCK:
+		init_special_inode(inode, cramfs_inode->mode,
+				old_decode_dev(cramfs_inode->size));
+		break;
+	default:
+		printk(KERN_DEBUG "CRAMFS: Invalid file type 0%04o for inode %llu.\n",
+		       inode->i_mode, inode->i_ino);
+		iget_failed(inode);
+		return ERR_PTR(-EIO);
+	}
+
+	inode->i_mode = cramfs_inode->mode;
+	i_uid_write(inode, cramfs_inode->uid);
+	i_gid_write(inode, cramfs_inode->gid);
+
+	/* if the lower 2 bits are zero, the inode contains data */
+	if (!(inode->i_ino & 3)) {
+		inode->i_size = cramfs_inode->size;
+		inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
+	}
+
+	/* Struct copy intentional */
+	inode_set_mtime_to_ts(inode,
+			      inode_set_atime_to_ts(inode, inode_set_ctime_to_ts(inode, zerotime)));
+	/* inode->i_nlink is left 1 - arguably wrong for directories,
+	   but it's the best we can do without reading the directory
+	   contents.  1 yields the right result in GNU find, even
+	   without -noleaf option. */
+
+	unlock_new_inode(inode);
+
+	return inode;
+}
+
+/*
+ * We have our own block cache: don't fill up the buffer cache
+ * with the rom-image, because the way the filesystem is set
+ * up the accesses should be fairly regular and cached in the
+ * page cache and dentry tree anyway..
+ *
+ * This also acts as a way to guarantee contiguous areas of up to
+ * BLKS_PER_BUF*PAGE_SIZE, so that the caller doesn't need to
+ * worry about end-of-buffer issues even when decompressing a full
+ * page cache.
+ *
+ * Note: This is all optimized away at compile time when
+ *       CONFIG_CRAMFS_BLOCKDEV=n.
+ */
+#define READ_BUFFERS (2)
+/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
+#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
+
+/*
+ * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
+ * data that takes up more space than the original and with unlucky
+ * alignment.
+ */
+#define BLKS_PER_BUF_SHIFT	(2)
+#define BLKS_PER_BUF		(1 << BLKS_PER_BUF_SHIFT)
+#define BUFFER_SIZE		(BLKS_PER_BUF*PAGE_SIZE)
+
+static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
+static unsigned buffer_blocknr[READ_BUFFERS];
+static struct super_block *buffer_dev[READ_BUFFERS];
+static int next_buffer;
+
+/*
+ * Populate our block cache and return a pointer to it.
+ */
+static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
+				unsigned int len)
+{
+	struct address_space *mapping = sb->s_bdev->bd_mapping;
+	struct file_ra_state ra = {};
+	struct page *pages[BLKS_PER_BUF];
+	unsigned i, blocknr, buffer;
+	unsigned long devsize;
+	char *data;
+
+	if (!len)
+		return NULL;
+	blocknr = offset >> PAGE_SHIFT;
+	offset &= PAGE_SIZE - 1;
+
+	/* Check if an existing buffer already has the data.. */
+	for (i = 0; i < READ_BUFFERS; i++) {
+		unsigned int blk_offset;
+
+		if (buffer_dev[i] != sb)
+			continue;
+		if (blocknr < buffer_blocknr[i])
+			continue;
+		blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT;
+		blk_offset += offset;
+		if (blk_offset > BUFFER_SIZE ||
+		    blk_offset + len > BUFFER_SIZE)
+			continue;
+		return read_buffers[i] + blk_offset;
+	}
+
+	devsize = bdev_nr_bytes(sb->s_bdev) >> PAGE_SHIFT;
+
+	/* Ok, read in BLKS_PER_BUF pages completely first. */
+	file_ra_state_init(&ra, mapping);
+	page_cache_sync_readahead(mapping, &ra, NULL, blocknr, BLKS_PER_BUF);
+
+	for (i = 0; i < BLKS_PER_BUF; i++) {
+		struct page *page = NULL;
+
+		if (blocknr + i < devsize) {
+			page = read_mapping_page(mapping, blocknr + i, NULL);
+			/* synchronous error? */
+			if (IS_ERR(page))
+				page = NULL;
+		}
+		pages[i] = page;
+	}
+
+	buffer = next_buffer;
+	next_buffer = NEXT_BUFFER(buffer);
+	buffer_blocknr[buffer] = blocknr;
+	buffer_dev[buffer] = sb;
+
+	data = read_buffers[buffer];
+	for (i = 0; i < BLKS_PER_BUF; i++) {
+		struct page *page = pages[i];
+
+		if (page) {
+			memcpy_from_page(data, page, 0, PAGE_SIZE);
+			put_page(page);
+		} else
+			memset(data, 0, PAGE_SIZE);
+		data += PAGE_SIZE;
+	}
+	return read_buffers[buffer] + offset;
+}
+
+/*
+ * Return a pointer to the linearly addressed cramfs image in memory.
+ */
+static void *cramfs_direct_read(struct super_block *sb, unsigned int offset,
+				unsigned int len)
+{
+	struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
+
+	if (!len)
+		return NULL;
+	if (len > sbi->size || offset > sbi->size - len)
+		return page_address(ZERO_PAGE(0));
+	return sbi->linear_virt_addr + offset;
+}
+
+/*
+ * Returns a pointer to a buffer containing at least LEN bytes of
+ * filesystem starting at byte offset OFFSET into the filesystem.
+ */
+static void *cramfs_read(struct super_block *sb, unsigned int offset,
+			 unsigned int len)
+{
+	struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
+
+	if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sbi->linear_virt_addr)
+		return cramfs_direct_read(sb, offset, len);
+	else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
+		return cramfs_blkdev_read(sb, offset, len);
+	else
+		return NULL;
+}
+
+/*
+ * For a mapping to be possible, we need a range of uncompressed and
+ * contiguous blocks. Return the offset for the first block and number of
+ * valid blocks for which that is true, or zero otherwise.
+ */
+static u32 cramfs_get_block_range(struct inode *inode, u32 pgoff, u32 *pages)
+{
+	struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
+	int i;
+	u32 *blockptrs, first_block_addr;
+
+	/*
+	 * We can dereference memory directly here as this code may be
+	 * reached only when there is a direct filesystem image mapping
+	 * available in memory.
+	 */
+	blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode) + pgoff * 4);
+	first_block_addr = blockptrs[0] & ~CRAMFS_BLK_FLAGS;
+	i = 0;
+	do {
+		u32 block_off = i * (PAGE_SIZE >> CRAMFS_BLK_DIRECT_PTR_SHIFT);
+		u32 expect = (first_block_addr + block_off) |
+			     CRAMFS_BLK_FLAG_DIRECT_PTR |
+			     CRAMFS_BLK_FLAG_UNCOMPRESSED;
+		if (blockptrs[i] != expect) {
+			pr_debug("range: block %d/%d got %#x expects %#x\n",
+				 pgoff+i, pgoff + *pages - 1,
+				 blockptrs[i], expect);
+			if (i == 0)
+				return 0;
+			break;
+		}
+	} while (++i < *pages);
+
+	*pages = i;
+	return first_block_addr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
+}
+
+#ifdef CONFIG_MMU
+
+/*
+ * Return true if the last page of a file in the filesystem image contains
+ * some other data that doesn't belong to that file. It is assumed that the
+ * last block is CRAMFS_BLK_FLAG_DIRECT_PTR | CRAMFS_BLK_FLAG_UNCOMPRESSED
+ * (verified by cramfs_get_block_range() and directly accessible in memory.
+ */
+static bool cramfs_last_page_is_shared(struct inode *inode)
+{
+	struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
+	u32 partial, last_page, blockaddr, *blockptrs;
+	char *tail_data;
+
+	partial = offset_in_page(inode->i_size);
+	if (!partial)
+		return false;
+	last_page = inode->i_size >> PAGE_SHIFT;
+	blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode));
+	blockaddr = blockptrs[last_page] & ~CRAMFS_BLK_FLAGS;
+	blockaddr <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
+	tail_data = sbi->linear_virt_addr + blockaddr + partial;
+	return memchr_inv(tail_data, 0, PAGE_SIZE - partial) ? true : false;
+}
+
+static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct inode *inode = file_inode(file);
+	struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
+	unsigned int pages, max_pages, offset;
+	unsigned long address, pgoff = vma->vm_pgoff;
+	char *bailout_reason;
+	int ret;
+
+	ret = generic_file_readonly_mmap(file, vma);
+	if (ret)
+		return ret;
+
+	/*
+	 * Now try to pre-populate ptes for this vma with a direct
+	 * mapping avoiding memory allocation when possible.
+	 */
+
+	/* Could COW work here? */
+	bailout_reason = "vma is writable";
+	if (vma->vm_flags & VM_WRITE)
+		goto bailout;
+
+	max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	bailout_reason = "beyond file limit";
+	if (pgoff >= max_pages)
+		goto bailout;
+	pages = min(vma_pages(vma), max_pages - pgoff);
+
+	offset = cramfs_get_block_range(inode, pgoff, &pages);
+	bailout_reason = "unsuitable block layout";
+	if (!offset)
+		goto bailout;
+	address = sbi->linear_phys_addr + offset;
+	bailout_reason = "data is not page aligned";
+	if (!PAGE_ALIGNED(address))
+		goto bailout;
+
+	/* Don't map the last page if it contains some other data */
+	if (pgoff + pages == max_pages && cramfs_last_page_is_shared(inode)) {
+		pr_debug("mmap: %pD: last page is shared\n", file);
+		pages--;
+	}
+
+	if (!pages) {
+		bailout_reason = "no suitable block remaining";
+		goto bailout;
+	}
+
+	if (pages == vma_pages(vma)) {
+		/*
+		 * The entire vma is mappable. remap_pfn_range() will
+		 * make it distinguishable from a non-direct mapping
+		 * in /proc/<pid>/maps by substituting the file offset
+		 * with the actual physical address.
+		 */
+		ret = remap_pfn_range(vma, vma->vm_start, address >> PAGE_SHIFT,
+				      pages * PAGE_SIZE, vma->vm_page_prot);
+	} else {
+		/*
+		 * Let's create a mixed map if we can't map it all.
+		 * The normal paging machinery will take care of the
+		 * unpopulated ptes via cramfs_read_folio().
+		 */
+		int i;
+		vm_flags_set(vma, VM_MIXEDMAP);
+		for (i = 0; i < pages && !ret; i++) {
+			vm_fault_t vmf;
+			unsigned long off = i * PAGE_SIZE;
+			vmf = vmf_insert_mixed(vma, vma->vm_start + off,
+					PHYS_PFN(address + off));
+			if (vmf & VM_FAULT_ERROR)
+				ret = vm_fault_to_errno(vmf, 0);
+		}
+	}
+
+	if (!ret)
+		pr_debug("mapped %pD[%lu] at 0x%08lx (%u/%lu pages) "
+			 "to vma 0x%08lx, page_prot 0x%llx\n", file,
+			 pgoff, address, pages, vma_pages(vma), vma->vm_start,
+			 (unsigned long long)pgprot_val(vma->vm_page_prot));
+	return ret;
+
+bailout:
+	pr_debug("%pD[%lu]: direct mmap impossible: %s\n",
+		 file, pgoff, bailout_reason);
+	/* Didn't manage any direct map, but normal paging is still possible */
+	return 0;
+}
+
+#else /* CONFIG_MMU */
+
+static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	return is_nommu_shared_mapping(vma->vm_flags) ? 0 : -ENOSYS;
+}
+
+static unsigned long cramfs_physmem_get_unmapped_area(struct file *file,
+			unsigned long addr, unsigned long len,
+			unsigned long pgoff, unsigned long flags)
+{
+	struct inode *inode = file_inode(file);
+	struct super_block *sb = inode->i_sb;
+	struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
+	unsigned int pages, block_pages, max_pages, offset;
+
+	pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	if (pgoff >= max_pages || pages > max_pages - pgoff)
+		return -EINVAL;
+	block_pages = pages;
+	offset = cramfs_get_block_range(inode, pgoff, &block_pages);
+	if (!offset || block_pages != pages)
+		return -ENOSYS;
+	addr = sbi->linear_phys_addr + offset;
+	pr_debug("get_unmapped for %pD ofs %#lx siz %lu at 0x%08lx\n",
+		 file, pgoff*PAGE_SIZE, len, addr);
+	return addr;
+}
+
+static unsigned int cramfs_physmem_mmap_capabilities(struct file *file)
+{
+	return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT |
+	       NOMMU_MAP_READ | NOMMU_MAP_EXEC;
+}
+
+#endif /* CONFIG_MMU */
+
+static const struct file_operations cramfs_physmem_fops = {
+	.llseek			= generic_file_llseek,
+	.read_iter		= generic_file_read_iter,
+	.splice_read		= filemap_splice_read,
+	.mmap			= cramfs_physmem_mmap,
+#ifndef CONFIG_MMU
+	.get_unmapped_area	= cramfs_physmem_get_unmapped_area,
+	.mmap_capabilities	= cramfs_physmem_mmap_capabilities,
+#endif
+};
+
+static void cramfs_kill_sb(struct super_block *sb)
+{
+	struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
+
+	generic_shutdown_super(sb);
+
+	if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sb->s_mtd) {
+		if (sbi && sbi->mtd_point_size)
+			mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size);
+		put_mtd_device(sb->s_mtd);
+		sb->s_mtd = NULL;
+	} else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) {
+		sync_blockdev(sb->s_bdev);
+		fs_bdev_file_release(sb->s_bdev_file, sb);
+	}
+	kfree(sbi);
+}
+
+static int cramfs_reconfigure(struct fs_context *fc)
+{
+	sync_filesystem(fc->root->d_sb);
+	fc->sb_flags |= SB_RDONLY;
+	return 0;
+}
+
+static int cramfs_read_super(struct super_block *sb, struct fs_context *fc,
+			     struct cramfs_super *super)
+{
+	struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
+	unsigned long root_offset;
+	bool silent = fc->sb_flags & SB_SILENT;
+
+	/* We don't know the real size yet */
+	sbi->size = PAGE_SIZE;
+
+	/* Read the first block and get the superblock from it */
+	mutex_lock(&read_mutex);
+	memcpy(super, cramfs_read(sb, 0, sizeof(*super)), sizeof(*super));
+	mutex_unlock(&read_mutex);
+
+	/* Do sanity checks on the superblock */
+	if (super->magic != CRAMFS_MAGIC) {
+		/* check for wrong endianness */
+		if (super->magic == CRAMFS_MAGIC_WEND) {
+			if (!silent)
+				errorfc(fc, "wrong endianness");
+			return -EINVAL;
+		}
+
+		/* check at 512 byte offset */
+		mutex_lock(&read_mutex);
+		memcpy(super,
+		       cramfs_read(sb, 512, sizeof(*super)),
+		       sizeof(*super));
+		mutex_unlock(&read_mutex);
+		if (super->magic != CRAMFS_MAGIC) {
+			if (super->magic == CRAMFS_MAGIC_WEND && !silent)
+				errorfc(fc, "wrong endianness");
+			else if (!silent)
+				errorfc(fc, "wrong magic");
+			return -EINVAL;
+		}
+	}
+
+	/* get feature flags first */
+	if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) {
+		errorfc(fc, "unsupported filesystem features");
+		return -EINVAL;
+	}
+
+	/* Check that the root inode is in a sane state */
+	if (!S_ISDIR(super->root.mode)) {
+		errorfc(fc, "root is not a directory");
+		return -EINVAL;
+	}
+	/* correct strange, hard-coded permissions of mkcramfs */
+	super->root.mode |= 0555;
+
+	root_offset = super->root.offset << 2;
+	if (super->flags & CRAMFS_FLAG_FSID_VERSION_2) {
+		sbi->size = super->size;
+		sbi->blocks = super->fsid.blocks;
+		sbi->files = super->fsid.files;
+	} else {
+		sbi->size = 1<<28;
+		sbi->blocks = 0;
+		sbi->files = 0;
+	}
+	sbi->magic = super->magic;
+	sbi->flags = super->flags;
+	if (root_offset == 0)
+		infofc(fc, "empty filesystem");
+	else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
+		 ((root_offset != sizeof(struct cramfs_super)) &&
+		  (root_offset != 512 + sizeof(struct cramfs_super))))
+	{
+		errorfc(fc, "bad root offset %lu", root_offset);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int cramfs_finalize_super(struct super_block *sb,
+				 struct cramfs_inode *cramfs_root)
+{
+	struct inode *root;
+
+	/* Set it all up.. */
+	sb->s_flags |= SB_RDONLY;
+	sb->s_time_min = 0;
+	sb->s_time_max = 0;
+	sb->s_op = &cramfs_ops;
+	root = get_cramfs_inode(sb, cramfs_root, 0);
+	if (IS_ERR(root))
+		return PTR_ERR(root);
+	sb->s_root = d_make_root(root);
+	if (!sb->s_root)
+		return -ENOMEM;
+	return 0;
+}
+
+static int cramfs_blkdev_fill_super(struct super_block *sb, struct fs_context *fc)
+{
+	struct cramfs_sb_info *sbi;
+	struct cramfs_super super;
+	int i, err;
+
+	sbi = kzalloc_obj(struct cramfs_sb_info);
+	if (!sbi)
+		return -ENOMEM;
+	sb->s_fs_info = sbi;
+
+	/* Invalidate the read buffers on mount: think disk change.. */
+	for (i = 0; i < READ_BUFFERS; i++)
+		buffer_blocknr[i] = -1;
+
+	err = cramfs_read_super(sb, fc, &super);
+	if (err)
+		return err;
+	return cramfs_finalize_super(sb, &super.root);
+}
+
+static int cramfs_mtd_fill_super(struct super_block *sb, struct fs_context *fc)
+{
+	struct cramfs_sb_info *sbi;
+	struct cramfs_super super;
+	int err;
+
+	sbi = kzalloc_obj(struct cramfs_sb_info);
+	if (!sbi)
+		return -ENOMEM;
+	sb->s_fs_info = sbi;
+
+	/* Map only one page for now.  Will remap it when fs size is known. */
+	err = mtd_point(sb->s_mtd, 0, PAGE_SIZE, &sbi->mtd_point_size,
+			&sbi->linear_virt_addr, &sbi->linear_phys_addr);
+	if (err || sbi->mtd_point_size != PAGE_SIZE) {
+		pr_err("unable to get direct memory access to mtd:%s\n",
+		       sb->s_mtd->name);
+		return err ? : -ENODATA;
+	}
+
+	pr_info("checking physical address %pap for linear cramfs image\n",
+		&sbi->linear_phys_addr);
+	err = cramfs_read_super(sb, fc, &super);
+	if (err)
+		return err;
+
+	/* Remap the whole filesystem now */
+	pr_info("linear cramfs image on mtd:%s appears to be %lu KB in size\n",
+		sb->s_mtd->name, sbi->size/1024);
+	mtd_unpoint(sb->s_mtd, 0, PAGE_SIZE);
+	err = mtd_point(sb->s_mtd, 0, sbi->size, &sbi->mtd_point_size,
+			&sbi->linear_virt_addr, &sbi->linear_phys_addr);
+	if (err || sbi->mtd_point_size != sbi->size) {
+		pr_err("unable to get direct memory access to mtd:%s\n",
+		       sb->s_mtd->name);
+		return err ? : -ENODATA;
+	}
+
+	return cramfs_finalize_super(sb, &super.root);
+}
+
+static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	struct super_block *sb = dentry->d_sb;
+	u64 id = 0;
+
+	if (sb->s_bdev)
+		id = huge_encode_dev(sb->s_bdev->bd_dev);
+	else if (sb->s_dev)
+		id = huge_encode_dev(sb->s_dev);
+
+	buf->f_type = CRAMFS_MAGIC;
+	buf->f_bsize = PAGE_SIZE;
+	buf->f_blocks = CRAMFS_SB(sb)->blocks;
+	buf->f_bfree = 0;
+	buf->f_bavail = 0;
+	buf->f_files = CRAMFS_SB(sb)->files;
+	buf->f_ffree = 0;
+	buf->f_fsid = u64_to_fsid(id);
+	buf->f_namelen = CRAMFS_MAXPATHLEN;
+	return 0;
+}
+
+/*
+ * Read a cramfs directory entry.
+ */
+static int cramfs_readdir(struct file *file, struct dir_context *ctx)
+{
+	struct inode *inode = file_inode(file);
+	struct super_block *sb = inode->i_sb;
+	char *buf;
+	unsigned int offset;
+
+	/* Offset within the thing. */
+	if (ctx->pos >= inode->i_size)
+		return 0;
+	offset = ctx->pos;
+	/* Directory entries are always 4-byte aligned */
+	if (offset & 3)
+		return -EINVAL;
+
+	buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	while (offset < inode->i_size) {
+		struct cramfs_inode *de;
+		unsigned long nextoffset;
+		char *name;
+		ino_t ino;
+		umode_t mode;
+		int namelen;
+
+		mutex_lock(&read_mutex);
+		de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
+		name = (char *)(de+1);
+
+		/*
+		 * Namelengths on disk are shifted by two
+		 * and the name padded out to 4-byte boundaries
+		 * with zeroes.
+		 */
+		namelen = de->namelen << 2;
+		memcpy(buf, name, namelen);
+		ino = cramino(de, OFFSET(inode) + offset);
+		mode = de->mode;
+		mutex_unlock(&read_mutex);
+		nextoffset = offset + sizeof(*de) + namelen;
+		for (;;) {
+			if (!namelen) {
+				kfree(buf);
+				return -EIO;
+			}
+			if (buf[namelen-1])
+				break;
+			namelen--;
+		}
+		if (!dir_emit(ctx, buf, namelen, ino, mode >> 12))
+			break;
+
+		ctx->pos = offset = nextoffset;
+	}
+	kfree(buf);
+	return 0;
+}
+
+/*
+ * Lookup and fill in the inode data..
+ */
+static struct dentry *cramfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
+{
+	unsigned int offset = 0;
+	struct inode *inode = NULL;
+	int sorted;
+
+	mutex_lock(&read_mutex);
+	sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
+	while (offset < dir->i_size) {
+		struct cramfs_inode *de;
+		char *name;
+		int namelen, retval;
+		int dir_off = OFFSET(dir) + offset;
+
+		de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
+		name = (char *)(de+1);
+
+		/* Try to take advantage of sorted directories */
+		if (sorted && (dentry->d_name.name[0] < name[0]))
+			break;
+
+		namelen = de->namelen << 2;
+		offset += sizeof(*de) + namelen;
+
+		/* Quick check that the name is roughly the right length */
+		if (((dentry->d_name.len + 3) & ~3) != namelen)
+			continue;
+
+		for (;;) {
+			if (!namelen) {
+				inode = ERR_PTR(-EIO);
+				goto out;
+			}
+			if (name[namelen-1])
+				break;
+			namelen--;
+		}
+		if (namelen != dentry->d_name.len)
+			continue;
+		retval = memcmp(dentry->d_name.name, name, namelen);
+		if (retval > 0)
+			continue;
+		if (!retval) {
+			inode = get_cramfs_inode(dir->i_sb, de, dir_off);
+			break;
+		}
+		/* else (retval < 0) */
+		if (sorted)
+			break;
+	}
+out:
+	mutex_unlock(&read_mutex);
+	return d_splice_alias(inode, dentry);
+}
+
+static int cramfs_read_folio(struct file *file, struct folio *folio)
+{
+	struct inode *inode = folio->mapping->host;
+	u32 maxblock;
+	int bytes_filled;
+	void *pgdata;
+	bool success = false;
+
+	maxblock = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	bytes_filled = 0;
+	pgdata = kmap_local_folio(folio, 0);
+
+	if (folio->index < maxblock) {
+		struct super_block *sb = inode->i_sb;
+		u32 blkptr_offset = OFFSET(inode) + folio->index * 4;
+		u32 block_ptr, block_start, block_len;
+		bool uncompressed, direct;
+
+		mutex_lock(&read_mutex);
+		block_ptr = *(u32 *) cramfs_read(sb, blkptr_offset, 4);
+		uncompressed = (block_ptr & CRAMFS_BLK_FLAG_UNCOMPRESSED);
+		direct = (block_ptr & CRAMFS_BLK_FLAG_DIRECT_PTR);
+		block_ptr &= ~CRAMFS_BLK_FLAGS;
+
+		if (direct) {
+			/*
+			 * The block pointer is an absolute start pointer,
+			 * shifted by 2 bits. The size is included in the
+			 * first 2 bytes of the data block when compressed,
+			 * or PAGE_SIZE otherwise.
+			 */
+			block_start = block_ptr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
+			if (uncompressed) {
+				block_len = PAGE_SIZE;
+				/* if last block: cap to file length */
+				if (folio->index == maxblock - 1)
+					block_len =
+						offset_in_page(inode->i_size);
+			} else {
+				block_len = *(u16 *)
+					cramfs_read(sb, block_start, 2);
+				block_start += 2;
+			}
+		} else {
+			/*
+			 * The block pointer indicates one past the end of
+			 * the current block (start of next block). If this
+			 * is the first block then it starts where the block
+			 * pointer table ends, otherwise its start comes
+			 * from the previous block's pointer.
+			 */
+			block_start = OFFSET(inode) + maxblock * 4;
+			if (folio->index)
+				block_start = *(u32 *)
+					cramfs_read(sb, blkptr_offset - 4, 4);
+			/* Beware... previous ptr might be a direct ptr */
+			if (unlikely(block_start & CRAMFS_BLK_FLAG_DIRECT_PTR)) {
+				/* See comments on earlier code. */
+				u32 prev_start = block_start;
+				block_start = prev_start & ~CRAMFS_BLK_FLAGS;
+				block_start <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
+				if (prev_start & CRAMFS_BLK_FLAG_UNCOMPRESSED) {
+					block_start += PAGE_SIZE;
+				} else {
+					block_len = *(u16 *)
+						cramfs_read(sb, block_start, 2);
+					block_start += 2 + block_len;
+				}
+			}
+			block_start &= ~CRAMFS_BLK_FLAGS;
+			block_len = block_ptr - block_start;
+		}
+
+		if (block_len == 0)
+			; /* hole */
+		else if (unlikely(block_len > 2*PAGE_SIZE ||
+				  (uncompressed && block_len > PAGE_SIZE))) {
+			mutex_unlock(&read_mutex);
+			pr_err("bad data blocksize %u\n", block_len);
+			goto err;
+		} else if (uncompressed) {
+			memcpy(pgdata,
+			       cramfs_read(sb, block_start, block_len),
+			       block_len);
+			bytes_filled = block_len;
+		} else {
+			bytes_filled = cramfs_uncompress_block(pgdata,
+				 PAGE_SIZE,
+				 cramfs_read(sb, block_start, block_len),
+				 block_len);
+		}
+		mutex_unlock(&read_mutex);
+		if (unlikely(bytes_filled < 0))
+			goto err;
+	}
+
+	memset(pgdata + bytes_filled, 0, PAGE_SIZE - bytes_filled);
+	flush_dcache_folio(folio);
+
+	success = true;
+err:
+	kunmap_local(pgdata);
+	folio_end_read(folio, success);
+	return 0;
+}
+
+static const struct address_space_operations cramfs_aops = {
+	.read_folio = cramfs_read_folio
+};
+
+/*
+ * Our operations:
+ */
+
+/*
+ * A directory can only readdir
+ */
+static const struct file_operations cramfs_directory_operations = {
+	.llseek		= generic_file_llseek,
+	.read		= generic_read_dir,
+	.iterate_shared	= cramfs_readdir,
+	.setlease	= generic_setlease,
+};
+
+static const struct inode_operations cramfs_dir_inode_operations = {
+	.lookup		= cramfs_lookup,
+};
+
+static const struct super_operations cramfs_ops = {
+	.statfs		= cramfs_statfs,
+};
+
+static int cramfs_get_tree(struct fs_context *fc)
+{
+	int ret = -ENOPROTOOPT;
+
+	if (IS_ENABLED(CONFIG_CRAMFS_MTD)) {
+		ret = get_tree_mtd(fc, cramfs_mtd_fill_super);
+		if (!ret)
+			return 0;
+	}
+	if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
+		ret = get_tree_bdev(fc, cramfs_blkdev_fill_super);
+	return ret;
+}
+
+static const struct fs_context_operations cramfs_context_ops = {
+	.get_tree	= cramfs_get_tree,
+	.reconfigure	= cramfs_reconfigure,
+};
+
+/*
+ * Set up the filesystem mount context.
+ */
+static int cramfs_init_fs_context(struct fs_context *fc)
+{
+	fc->ops = &cramfs_context_ops;
+	return 0;
+}
+
+static struct file_system_type cramfs_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "cramfs",
+	.init_fs_context = cramfs_init_fs_context,
+	.kill_sb	= cramfs_kill_sb,
+	.fs_flags	= FS_REQUIRES_DEV,
+};
+MODULE_ALIAS_FS("cramfs");
+
+static int __init init_cramfs_fs(void)
+{
+	int rv;
+
+	rv = cramfs_uncompress_init();
+	if (rv < 0)
+		return rv;
+	rv = register_filesystem(&cramfs_fs_type);
+	if (rv < 0)
+		cramfs_uncompress_exit();
+	return rv;
+}
+
+static void __exit exit_cramfs_fs(void)
+{
+	cramfs_uncompress_exit();
+	unregister_filesystem(&cramfs_fs_type);
+}
+
+module_init(init_cramfs_fs)
+module_exit(exit_cramfs_fs)
+MODULE_DESCRIPTION("Compressed ROM file system support");
+MODULE_LICENSE("GPL");
diff --git a/fs/cramfs/internal.h b/fs/cramfs/internal.h
new file mode 100644
index 000000000..349d71272
--- /dev/null
+++ b/fs/cramfs/internal.h
@@ -0,0 +1,4 @@
+/* Uncompression interfaces to the underlying zlib */
+int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen);
+int cramfs_uncompress_init(void);
+void cramfs_uncompress_exit(void);
diff --git a/fs/cramfs/uncompress.c b/fs/cramfs/uncompress.c
new file mode 100644
index 000000000..975d98fc2
--- /dev/null
+++ b/fs/cramfs/uncompress.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * uncompress.c
+ *
+ * (C) Copyright 1999 Linus Torvalds
+ *
+ * cramfs interfaces to the uncompression library. There's really just
+ * three entrypoints:
+ *
+ *  - cramfs_uncompress_init() - called to initialize the thing.
+ *  - cramfs_uncompress_exit() - tell me when you're done
+ *  - cramfs_uncompress_block() - uncompress a block.
+ *
+ * NOTE NOTE NOTE! The uncompression is entirely single-threaded. We
+ * only have one stream, and we'll initialize it only once even if it
+ * then is used by multiple filesystems.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/vmalloc.h>
+#include <linux/zlib.h>
+#include "internal.h"
+
+static z_stream stream;
+static int initialized;
+
+/* Returns length of decompressed data. */
+int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen)
+{
+	int err;
+
+	stream.next_in = src;
+	stream.avail_in = srclen;
+
+	stream.next_out = dst;
+	stream.avail_out = dstlen;
+
+	err = zlib_inflateReset(&stream);
+	if (err != Z_OK) {
+		pr_err("zlib_inflateReset error %d\n", err);
+		zlib_inflateEnd(&stream);
+		zlib_inflateInit(&stream);
+	}
+
+	err = zlib_inflate(&stream, Z_FINISH);
+	if (err != Z_STREAM_END)
+		goto err;
+	return stream.total_out;
+
+err:
+	pr_err("Error %d while decompressing!\n", err);
+	pr_err("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen);
+	return -EIO;
+}
+
+int cramfs_uncompress_init(void)
+{
+	if (!initialized++) {
+		stream.workspace = vmalloc(zlib_inflate_workspacesize());
+		if (!stream.workspace) {
+			initialized = 0;
+			return -ENOMEM;
+		}
+		stream.next_in = NULL;
+		stream.avail_in = 0;
+		zlib_inflateInit(&stream);
+	}
+	return 0;
+}
+
+void cramfs_uncompress_exit(void)
+{
+	if (!--initialized) {
+		zlib_inflateEnd(&stream);
+		vfree(stream.workspace);
+	}
+}