Resguardo inicial

linux-7.2.3/fs/ramfs/Makefile

@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for the linux ramfs routines.
+#
+
+obj-y += ramfs.o
+
+file-mmu-y := file-nommu.o
+file-mmu-$(CONFIG_MMU) := file-mmu.o
+ramfs-objs += inode.o $(file-mmu-y)

linux-7.2.3/fs/ramfs/file-mmu.c

@@ -0,0 +1,55 @@
+/* file-mmu.c: ramfs MMU-based file operations
+ *
+ * Resizable simple ram filesystem for Linux.
+ *
+ * Copyright (C) 2000 Linus Torvalds.
+ *               2000 Transmeta Corp.
+ *
+ * Usage limits added by David Gibson, Linuxcare Australia.
+ * This file is released under the GPL.
+ */
+
+/*
+ * NOTE! This filesystem is probably most useful
+ * not as a real filesystem, but as an example of
+ * how virtual filesystems can be written.
+ *
+ * It doesn't get much simpler than this. Consider
+ * that this file implements the full semantics of
+ * a POSIX-compliant read-write filesystem.
+ *
+ * Note in particular how the filesystem does not
+ * need to implement any data structures of its own
+ * to keep track of the virtual data: using the VFS
+ * caches is sufficient.
+ */
+
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/ramfs.h>
+#include <linux/sched.h>
+
+#include "internal.h"
+
+static unsigned long ramfs_mmu_get_unmapped_area(struct file *file,
+		unsigned long addr, unsigned long len, unsigned long pgoff,
+		unsigned long flags)
+{
+	return mm_get_unmapped_area(file, addr, len, pgoff, flags);
+}
+
+const struct file_operations ramfs_file_operations = {
+	.read_iter	= generic_file_read_iter,
+	.write_iter	= generic_file_write_iter,
+	.mmap_prepare	= generic_file_mmap_prepare,
+	.fsync		= noop_fsync,
+	.splice_read	= filemap_splice_read,
+	.splice_write	= iter_file_splice_write,
+	.llseek		= generic_file_llseek,
+	.get_unmapped_area	= ramfs_mmu_get_unmapped_area,
+};
+
+const struct inode_operations ramfs_file_inode_operations = {
+	.setattr	= simple_setattr,
+	.getattr	= simple_getattr,
+};

linux-7.2.3/fs/ramfs/file-nommu.c

@@ -0,0 +1,273 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* file-nommu.c: no-MMU version of ramfs
+ *
+ * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/backing-dev.h>
+#include <linux/ramfs.h>
+#include <linux/folio_batch.h>
+#include <linux/mman.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#include <linux/uaccess.h>
+#include "internal.h"
+
+static int ramfs_nommu_setattr(struct mnt_idmap *, struct dentry *, struct iattr *);
+static unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
+						   unsigned long addr,
+						   unsigned long len,
+						   unsigned long pgoff,
+						   unsigned long flags);
+static int ramfs_nommu_mmap_prepare(struct vm_area_desc *desc);
+
+static unsigned ramfs_mmap_capabilities(struct file *file)
+{
+	return NOMMU_MAP_DIRECT | NOMMU_MAP_COPY | NOMMU_MAP_READ |
+		NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;
+}
+
+const struct file_operations ramfs_file_operations = {
+	.mmap_capabilities	= ramfs_mmap_capabilities,
+	.mmap_prepare		= ramfs_nommu_mmap_prepare,
+	.get_unmapped_area	= ramfs_nommu_get_unmapped_area,
+	.read_iter		= generic_file_read_iter,
+	.write_iter		= generic_file_write_iter,
+	.fsync			= noop_fsync,
+	.splice_read		= filemap_splice_read,
+	.splice_write		= iter_file_splice_write,
+	.llseek			= generic_file_llseek,
+};
+
+const struct inode_operations ramfs_file_inode_operations = {
+	.setattr		= ramfs_nommu_setattr,
+	.getattr		= simple_getattr,
+};
+
+/*****************************************************************************/
+/*
+ * add a contiguous set of pages into a ramfs inode when it's truncated from
+ * size 0 on the assumption that it's going to be used for an mmap of shared
+ * memory
+ */
+int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
+{
+	unsigned long npages, xpages, loop;
+	struct page *pages;
+	unsigned order;
+	void *data;
+	int ret;
+	gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
+
+	/* make various checks */
+	order = get_order(newsize);
+	if (unlikely(order > MAX_PAGE_ORDER))
+		return -EFBIG;
+
+	ret = inode_newsize_ok(inode, newsize);
+	if (ret)
+		return ret;
+
+	i_size_write(inode, newsize);
+
+	/* allocate enough contiguous pages to be able to satisfy the
+	 * request */
+	pages = alloc_pages(gfp, order);
+	if (!pages)
+		return -ENOMEM;
+
+	/* split the high-order page into an array of single pages */
+	xpages = 1UL << order;
+	npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+	split_page(pages, order);
+
+	/* trim off any pages we don't actually require */
+	for (loop = npages; loop < xpages; loop++)
+		__free_page(pages + loop);
+
+	/* clear the memory we allocated */
+	newsize = PAGE_SIZE * npages;
+	data = page_address(pages);
+	memset(data, 0, newsize);
+
+	/* attach all the pages to the inode's address space */
+	for (loop = 0; loop < npages; loop++) {
+		struct page *page = pages + loop;
+
+		ret = add_to_page_cache_lru(page, inode->i_mapping, loop,
+					gfp);
+		if (ret < 0)
+			goto add_error;
+
+		/* prevent the page from being discarded on memory pressure */
+		SetPageDirty(page);
+		SetPageUptodate(page);
+
+		unlock_page(page);
+		put_page(page);
+	}
+
+	return 0;
+
+add_error:
+	while (loop < npages)
+		__free_page(pages + loop++);
+	return ret;
+}
+
+/*****************************************************************************/
+/*
+ *
+ */
+static int ramfs_nommu_resize(struct inode *inode, loff_t newsize, loff_t size)
+{
+	int ret;
+
+	/* assume a truncate from zero size is going to be for the purposes of
+	 * shared mmap */
+	if (size == 0) {
+		if (unlikely(newsize >> 32))
+			return -EFBIG;
+
+		return ramfs_nommu_expand_for_mapping(inode, newsize);
+	}
+
+	/* check that a decrease in size doesn't cut off any shared mappings */
+	if (newsize < size) {
+		ret = nommu_shrink_inode_mappings(inode, size, newsize);
+		if (ret < 0)
+			return ret;
+	}
+
+	truncate_setsize(inode, newsize);
+	return 0;
+}
+
+/*****************************************************************************/
+/*
+ * handle a change of attributes
+ * - we're specifically interested in a change of size
+ */
+static int ramfs_nommu_setattr(struct mnt_idmap *idmap,
+			       struct dentry *dentry, struct iattr *ia)
+{
+	struct inode *inode = d_inode(dentry);
+	unsigned int old_ia_valid = ia->ia_valid;
+	int ret = 0;
+
+	/* POSIX UID/GID verification for setting inode attributes */
+	ret = setattr_prepare(&nop_mnt_idmap, dentry, ia);
+	if (ret)
+		return ret;
+
+	/* pick out size-changing events */
+	if (ia->ia_valid & ATTR_SIZE) {
+		loff_t size = inode->i_size;
+
+		if (ia->ia_size != size) {
+			ret = ramfs_nommu_resize(inode, ia->ia_size, size);
+			if (ret < 0 || ia->ia_valid == ATTR_SIZE)
+				goto out;
+		} else {
+			/* we skipped the truncate but must still update
+			 * timestamps
+			 */
+			ia->ia_valid |= ATTR_MTIME|ATTR_CTIME;
+		}
+	}
+
+	setattr_copy(&nop_mnt_idmap, inode, ia);
+ out:
+	ia->ia_valid = old_ia_valid;
+	return ret;
+}
+
+/*****************************************************************************/
+/*
+ * try to determine where a shared mapping can be made
+ * - we require that:
+ *   - the pages to be mapped must exist
+ *   - the pages be physically contiguous in sequence
+ */
+static unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
+					    unsigned long addr, unsigned long len,
+					    unsigned long pgoff, unsigned long flags)
+{
+	unsigned long maxpages, lpages, nr_folios, loop, ret, nr_pages, pfn;
+	struct inode *inode = file_inode(file);
+	struct folio_batch fbatch;
+	loff_t isize;
+
+	/* the mapping mustn't extend beyond the EOF */
+	lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	isize = i_size_read(inode);
+
+	ret = -ENOSYS;
+	maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	if (pgoff >= maxpages)
+		goto out;
+
+	if (maxpages - pgoff < lpages)
+		goto out;
+
+	/* gang-find the pages */
+	folio_batch_init(&fbatch);
+	nr_pages = 0;
+repeat:
+	nr_folios = filemap_get_folios_contig(inode->i_mapping, &pgoff,
+			ULONG_MAX, &fbatch);
+	if (!nr_folios) {
+		ret = -ENOSYS;
+		return ret;
+	}
+
+	if (ret == -ENOSYS) {
+		ret = (unsigned long) folio_address(fbatch.folios[0]);
+		pfn = folio_pfn(fbatch.folios[0]);
+	}
+	/* check the pages for physical adjacency */
+	for (loop = 0; loop < nr_folios; loop++) {
+		if (pfn + nr_pages != folio_pfn(fbatch.folios[loop])) {
+			ret = -ENOSYS;
+			goto out_free; /* leave if not physical adjacent */
+		}
+		nr_pages += folio_nr_pages(fbatch.folios[loop]);
+		if (nr_pages >= lpages)
+			goto out_free; /* successfully found desired pages*/
+	}
+
+	if (nr_pages < lpages) {
+		folio_batch_release(&fbatch);
+		goto repeat; /* loop if pages are missing */
+	}
+	/* okay - all conditions fulfilled */
+
+out_free:
+	folio_batch_release(&fbatch);
+out:
+	return ret;
+}
+
+/*****************************************************************************/
+/*
+ * set up a mapping for shared memory segments
+ */
+static int ramfs_nommu_mmap_prepare(struct vm_area_desc *desc)
+{
+	if (!is_nommu_shared_vma_flags(&desc->vma_flags))
+		return -ENOSYS;
+
+	file_accessed(desc->file);
+	desc->vm_ops = &generic_file_vm_ops;
+	return 0;
+}

linux-7.2.3/fs/ramfs/inode.c

@@ -0,0 +1,329 @@
+/*
+ * Resizable simple ram filesystem for Linux.
+ *
+ * Copyright (C) 2000 Linus Torvalds.
+ *               2000 Transmeta Corp.
+ *
+ * Usage limits added by David Gibson, Linuxcare Australia.
+ * This file is released under the GPL.
+ */
+
+/*
+ * NOTE! This filesystem is probably most useful
+ * not as a real filesystem, but as an example of
+ * how virtual filesystems can be written.
+ *
+ * It doesn't get much simpler than this. Consider
+ * that this file implements the full semantics of
+ * a POSIX-compliant read-write filesystem.
+ *
+ * Note in particular how the filesystem does not
+ * need to implement any data structures of its own
+ * to keep track of the virtual data: using the VFS
+ * caches is sufficient.
+ */
+
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/backing-dev.h>
+#include <linux/ramfs.h>
+#include <linux/sched.h>
+#include <linux/parser.h>
+#include <linux/magic.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
+#include <linux/seq_file.h>
+#include "internal.h"
+
+struct ramfs_mount_opts {
+	umode_t mode;
+};
+
+struct ramfs_fs_info {
+	struct ramfs_mount_opts mount_opts;
+};
+
+#define RAMFS_DEFAULT_MODE	0755
+
+static const struct super_operations ramfs_ops;
+static const struct inode_operations ramfs_dir_inode_operations;
+
+struct inode *ramfs_get_inode(struct super_block *sb,
+				const struct inode *dir, umode_t mode, dev_t dev)
+{
+	struct inode * inode = new_inode(sb);
+
+	if (inode) {
+		inode->i_ino = get_next_ino();
+		inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
+		inode->i_mapping->a_ops = &ram_aops;
+		mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
+		mapping_set_unevictable(inode->i_mapping);
+		simple_inode_init_ts(inode);
+		switch (mode & S_IFMT) {
+		default:
+			init_special_inode(inode, mode, dev);
+			break;
+		case S_IFREG:
+			inode->i_op = &ramfs_file_inode_operations;
+			inode->i_fop = &ramfs_file_operations;
+			break;
+		case S_IFDIR:
+			inode->i_op = &ramfs_dir_inode_operations;
+			inode->i_fop = &simple_dir_operations;
+
+			/* directory inodes start off with i_nlink == 2 (for "." entry) */
+			inc_nlink(inode);
+			break;
+		case S_IFLNK:
+			inode->i_op = &page_symlink_inode_operations;
+			inode_nohighmem(inode);
+			break;
+		}
+	}
+	return inode;
+}
+
+/*
+ * File creation. Allocate an inode, and we're done..
+ */
+/* SMP-safe */
+static int
+ramfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
+	    struct dentry *dentry, umode_t mode, dev_t dev)
+{
+	struct inode * inode = ramfs_get_inode(dir->i_sb, dir, mode, dev);
+	int error = -ENOSPC;
+
+	if (inode) {
+		error = security_inode_init_security(inode, dir,
+						     &dentry->d_name, NULL,
+						     NULL);
+		if (error) {
+			iput(inode);
+			goto out;
+		}
+
+		d_make_persistent(dentry, inode);
+		error = 0;
+		inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
+	}
+out:
+	return error;
+}
+
+static struct dentry *ramfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
+				 struct dentry *dentry, umode_t mode)
+{
+	int retval = ramfs_mknod(&nop_mnt_idmap, dir, dentry, mode | S_IFDIR, 0);
+	if (!retval)
+		inc_nlink(dir);
+	return ERR_PTR(retval);
+}
+
+static int ramfs_create(struct mnt_idmap *idmap, struct inode *dir,
+			struct dentry *dentry, umode_t mode, bool excl)
+{
+	return ramfs_mknod(&nop_mnt_idmap, dir, dentry, mode | S_IFREG, 0);
+}
+
+static int ramfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
+			 struct dentry *dentry, const char *symname)
+{
+	struct inode *inode;
+	int error = -ENOSPC;
+
+	inode = ramfs_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0);
+	if (inode) {
+		int l = strlen(symname)+1;
+
+		error = security_inode_init_security(inode, dir,
+						     &dentry->d_name, NULL,
+						     NULL);
+		if (error) {
+			iput(inode);
+			goto out;
+		}
+
+		error = page_symlink(inode, symname, l);
+		if (!error) {
+			d_make_persistent(dentry, inode);
+			inode_set_mtime_to_ts(dir,
+					      inode_set_ctime_current(dir));
+		} else
+			iput(inode);
+	}
+out:
+	return error;
+}
+
+static int ramfs_tmpfile(struct mnt_idmap *idmap,
+			 struct inode *dir, struct file *file, umode_t mode)
+{
+	struct inode *inode;
+	int error;
+
+	inode = ramfs_get_inode(dir->i_sb, dir, mode, 0);
+	if (!inode)
+		return -ENOSPC;
+
+	error = security_inode_init_security(inode, dir,
+					     &file_dentry(file)->d_name, NULL,
+					     NULL);
+	if (error) {
+		iput(inode);
+		goto out;
+	}
+
+	d_tmpfile(file, inode);
+out:
+	return finish_open_simple(file, error);
+}
+
+static const struct inode_operations ramfs_dir_inode_operations = {
+	.create		= ramfs_create,
+	.lookup		= simple_lookup,
+	.link		= simple_link,
+	.unlink		= simple_unlink,
+	.symlink	= ramfs_symlink,
+	.mkdir		= ramfs_mkdir,
+	.rmdir		= simple_rmdir,
+	.mknod		= ramfs_mknod,
+	.rename		= simple_rename,
+	.tmpfile	= ramfs_tmpfile,
+};
+
+/*
+ * Display the mount options in /proc/mounts.
+ */
+static int ramfs_show_options(struct seq_file *m, struct dentry *root)
+{
+	struct ramfs_fs_info *fsi = root->d_sb->s_fs_info;
+
+	if (fsi->mount_opts.mode != RAMFS_DEFAULT_MODE)
+		seq_printf(m, ",mode=%o", fsi->mount_opts.mode);
+	return 0;
+}
+
+static const struct super_operations ramfs_ops = {
+	.statfs		= simple_statfs,
+	.drop_inode	= inode_just_drop,
+	.show_options	= ramfs_show_options,
+};
+
+enum ramfs_param {
+	Opt_mode,
+};
+
+const struct fs_parameter_spec ramfs_fs_parameters[] = {
+	fsparam_u32oct("mode",	Opt_mode),
+	{}
+};
+
+static int ramfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	struct fs_parse_result result;
+	struct ramfs_fs_info *fsi = fc->s_fs_info;
+	int opt;
+
+	opt = fs_parse(fc, ramfs_fs_parameters, param, &result);
+	if (opt == -ENOPARAM) {
+		opt = vfs_parse_fs_param_source(fc, param);
+		if (opt != -ENOPARAM)
+			return opt;
+		/*
+		 * We might like to report bad mount options here;
+		 * but traditionally ramfs has ignored all mount options,
+		 * and as it is used as a !CONFIG_SHMEM simple substitute
+		 * for tmpfs, better continue to ignore other mount options.
+		 */
+		return 0;
+	}
+	if (opt < 0)
+		return opt;
+
+	switch (opt) {
+	case Opt_mode:
+		fsi->mount_opts.mode = result.uint_32 & S_IALLUGO;
+		break;
+	}
+
+	return 0;
+}
+
+static int ramfs_fill_super(struct super_block *sb, struct fs_context *fc)
+{
+	struct ramfs_fs_info *fsi = sb->s_fs_info;
+	struct inode *inode;
+
+	sb->s_maxbytes		= MAX_LFS_FILESIZE;
+	sb->s_blocksize		= PAGE_SIZE;
+	sb->s_blocksize_bits	= PAGE_SHIFT;
+	sb->s_magic		= RAMFS_MAGIC;
+	sb->s_op		= &ramfs_ops;
+	sb->s_d_flags		= DCACHE_DONTCACHE;
+	sb->s_time_gran		= 1;
+
+	inode = ramfs_get_inode(sb, NULL, S_IFDIR | fsi->mount_opts.mode, 0);
+	sb->s_root = d_make_root(inode);
+	if (!sb->s_root)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int ramfs_get_tree(struct fs_context *fc)
+{
+	return get_tree_nodev(fc, ramfs_fill_super);
+}
+
+static void ramfs_free_fc(struct fs_context *fc)
+{
+	kfree(fc->s_fs_info);
+}
+
+static const struct fs_context_operations ramfs_context_ops = {
+	.free		= ramfs_free_fc,
+	.parse_param	= ramfs_parse_param,
+	.get_tree	= ramfs_get_tree,
+};
+
+int ramfs_init_fs_context(struct fs_context *fc)
+{
+	struct ramfs_fs_info *fsi;
+
+	fsi = kzalloc_obj(*fsi);
+	if (!fsi)
+		return -ENOMEM;
+
+	fsi->mount_opts.mode = RAMFS_DEFAULT_MODE;
+	fc->s_fs_info = fsi;
+	fc->ops = &ramfs_context_ops;
+	return 0;
+}
+
+void ramfs_kill_sb(struct super_block *sb)
+{
+	kfree(sb->s_fs_info);
+	kill_anon_super(sb);
+}
+
+static struct file_system_type ramfs_fs_type = {
+	.name		= "ramfs",
+	.init_fs_context = ramfs_init_fs_context,
+	.parameters	= ramfs_fs_parameters,
+	.kill_sb	= ramfs_kill_sb,
+	.fs_flags	= FS_USERNS_MOUNT,
+};
+
+static int __init init_ramfs_fs(void)
+{
+	return register_filesystem(&ramfs_fs_type);
+}
+fs_initcall(init_ramfs_fs);

linux-7.2.3/fs/ramfs/internal.h

@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* internal.h: ramfs internal definitions
+ *
+ * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+
+extern const struct inode_operations ramfs_file_inode_operations;