1 files changed, 615 insertions, 0 deletions

diff --git a/fs/erofs/super.c b/fs/erofs/super.c
new file mode 100644
index 000000000000..caf9a95173b0
--- /dev/null
+++ b/fs/erofs/super.c
@@ -0,0 +1,615 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017-2018 HUAWEI, Inc.
+ *             http://www.huawei.com/
+ * Created by Gao Xiang <gaoxiang25@huawei.com>
+ */
+#include <linux/module.h>
+#include <linux/buffer_head.h>
+#include <linux/statfs.h>
+#include <linux/parser.h>
+#include <linux/seq_file.h>
+#include "xattr.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/erofs.h>
+
+static struct kmem_cache *erofs_inode_cachep __read_mostly;
+
+void _erofs_err(struct super_block *sb, const char *function,
+		const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	pr_err("(device %s): %s: %pV", sb->s_id, function, &vaf);
+	va_end(args);
+}
+
+void _erofs_info(struct super_block *sb, const char *function,
+		 const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	pr_info("(device %s): %pV", sb->s_id, &vaf);
+	va_end(args);
+}
+
+static void erofs_inode_init_once(void *ptr)
+{
+	struct erofs_inode *vi = ptr;
+
+	inode_init_once(&vi->vfs_inode);
+}
+
+static struct inode *erofs_alloc_inode(struct super_block *sb)
+{
+	struct erofs_inode *vi =
+		kmem_cache_alloc(erofs_inode_cachep, GFP_KERNEL);
+
+	if (!vi)
+		return NULL;
+
+	/* zero out everything except vfs_inode */
+	memset(vi, 0, offsetof(struct erofs_inode, vfs_inode));
+	return &vi->vfs_inode;
+}
+
+static void erofs_free_inode(struct inode *inode)
+{
+	struct erofs_inode *vi = EROFS_I(inode);
+
+	/* be careful of RCU symlink path */
+	if (inode->i_op == &erofs_fast_symlink_iops)
+		kfree(inode->i_link);
+	kfree(vi->xattr_shared_xattrs);
+
+	kmem_cache_free(erofs_inode_cachep, vi);
+}
+
+static bool check_layout_compatibility(struct super_block *sb,
+				       struct erofs_super_block *dsb)
+{
+	const unsigned int feature = le32_to_cpu(dsb->feature_incompat);
+
+	EROFS_SB(sb)->feature_incompat = feature;
+
+	/* check if current kernel meets all mandatory requirements */
+	if (feature & (~EROFS_ALL_FEATURE_INCOMPAT)) {
+		erofs_err(sb,
+			  "unidentified incompatible feature %x, please upgrade kernel version",
+			   feature & ~EROFS_ALL_FEATURE_INCOMPAT);
+		return false;
+	}
+	return true;
+}
+
+static int erofs_read_superblock(struct super_block *sb)
+{
+	struct erofs_sb_info *sbi;
+	struct page *page;
+	struct erofs_super_block *dsb;
+	unsigned int blkszbits;
+	void *data;
+	int ret;
+
+	page = read_mapping_page(sb->s_bdev->bd_inode->i_mapping, 0, NULL);
+	if (!page) {
+		erofs_err(sb, "cannot read erofs superblock");
+		return -EIO;
+	}
+
+	sbi = EROFS_SB(sb);
+
+	data = kmap_atomic(page);
+	dsb = (struct erofs_super_block *)(data + EROFS_SUPER_OFFSET);
+
+	ret = -EINVAL;
+	if (le32_to_cpu(dsb->magic) != EROFS_SUPER_MAGIC_V1) {
+		erofs_err(sb, "cannot find valid erofs superblock");
+		goto out;
+	}
+
+	blkszbits = dsb->blkszbits;
+	/* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */
+	if (blkszbits != LOG_BLOCK_SIZE) {
+		erofs_err(sb, "blksize %u isn't supported on this platform",
+			  1 << blkszbits);
+		goto out;
+	}
+
+	if (!check_layout_compatibility(sb, dsb))
+		goto out;
+
+	sbi->blocks = le32_to_cpu(dsb->blocks);
+	sbi->meta_blkaddr = le32_to_cpu(dsb->meta_blkaddr);
+#ifdef CONFIG_EROFS_FS_XATTR
+	sbi->xattr_blkaddr = le32_to_cpu(dsb->xattr_blkaddr);
+#endif
+	sbi->islotbits = ilog2(sizeof(struct erofs_inode_compact));
+	sbi->root_nid = le16_to_cpu(dsb->root_nid);
+	sbi->inos = le64_to_cpu(dsb->inos);
+
+	sbi->build_time = le64_to_cpu(dsb->build_time);
+	sbi->build_time_nsec = le32_to_cpu(dsb->build_time_nsec);
+
+	memcpy(&sb->s_uuid, dsb->uuid, sizeof(dsb->uuid));
+
+	ret = strscpy(sbi->volume_name, dsb->volume_name,
+		      sizeof(dsb->volume_name));
+	if (ret < 0) {	/* -E2BIG */
+		erofs_err(sb, "bad volume name without NIL terminator");
+		ret = -EFSCORRUPTED;
+		goto out;
+	}
+	ret = 0;
+out:
+	kunmap_atomic(data);
+	put_page(page);
+	return ret;
+}
+
+#ifdef CONFIG_EROFS_FS_ZIP
+static int erofs_build_cache_strategy(struct super_block *sb,
+				      substring_t *args)
+{
+	struct erofs_sb_info *sbi = EROFS_SB(sb);
+	const char *cs = match_strdup(args);
+	int err = 0;
+
+	if (!cs) {
+		erofs_err(sb, "Not enough memory to store cache strategy");
+		return -ENOMEM;
+	}
+
+	if (!strcmp(cs, "disabled")) {
+		sbi->cache_strategy = EROFS_ZIP_CACHE_DISABLED;
+	} else if (!strcmp(cs, "readahead")) {
+		sbi->cache_strategy = EROFS_ZIP_CACHE_READAHEAD;
+	} else if (!strcmp(cs, "readaround")) {
+		sbi->cache_strategy = EROFS_ZIP_CACHE_READAROUND;
+	} else {
+		erofs_err(sb, "Unrecognized cache strategy \"%s\"", cs);
+		err = -EINVAL;
+	}
+	kfree(cs);
+	return err;
+}
+#else
+static int erofs_build_cache_strategy(struct super_block *sb,
+				      substring_t *args)
+{
+	erofs_info(sb, "EROFS compression is disabled, so cache strategy is ignored");
+	return 0;
+}
+#endif
+
+/* set up default EROFS parameters */
+static void erofs_default_options(struct erofs_sb_info *sbi)
+{
+#ifdef CONFIG_EROFS_FS_ZIP
+	sbi->cache_strategy = EROFS_ZIP_CACHE_READAROUND;
+	sbi->max_sync_decompress_pages = 3;
+#endif
+#ifdef CONFIG_EROFS_FS_XATTR
+	set_opt(sbi, XATTR_USER);
+#endif
+#ifdef CONFIG_EROFS_FS_POSIX_ACL
+	set_opt(sbi, POSIX_ACL);
+#endif
+}
+
+enum {
+	Opt_user_xattr,
+	Opt_nouser_xattr,
+	Opt_acl,
+	Opt_noacl,
+	Opt_cache_strategy,
+	Opt_err
+};
+
+static match_table_t erofs_tokens = {
+	{Opt_user_xattr, "user_xattr"},
+	{Opt_nouser_xattr, "nouser_xattr"},
+	{Opt_acl, "acl"},
+	{Opt_noacl, "noacl"},
+	{Opt_cache_strategy, "cache_strategy=%s"},
+	{Opt_err, NULL}
+};
+
+static int erofs_parse_options(struct super_block *sb, char *options)
+{
+	substring_t args[MAX_OPT_ARGS];
+	char *p;
+	int err;
+
+	if (!options)
+		return 0;
+
+	while ((p = strsep(&options, ","))) {
+		int token;
+
+		if (!*p)
+			continue;
+
+		args[0].to = args[0].from = NULL;
+		token = match_token(p, erofs_tokens, args);
+
+		switch (token) {
+#ifdef CONFIG_EROFS_FS_XATTR
+		case Opt_user_xattr:
+			set_opt(EROFS_SB(sb), XATTR_USER);
+			break;
+		case Opt_nouser_xattr:
+			clear_opt(EROFS_SB(sb), XATTR_USER);
+			break;
+#else
+		case Opt_user_xattr:
+			erofs_info(sb, "user_xattr options not supported");
+			break;
+		case Opt_nouser_xattr:
+			erofs_info(sb, "nouser_xattr options not supported");
+			break;
+#endif
+#ifdef CONFIG_EROFS_FS_POSIX_ACL
+		case Opt_acl:
+			set_opt(EROFS_SB(sb), POSIX_ACL);
+			break;
+		case Opt_noacl:
+			clear_opt(EROFS_SB(sb), POSIX_ACL);
+			break;
+#else
+		case Opt_acl:
+			erofs_info(sb, "acl options not supported");
+			break;
+		case Opt_noacl:
+			erofs_info(sb, "noacl options not supported");
+			break;
+#endif
+		case Opt_cache_strategy:
+			err = erofs_build_cache_strategy(sb, args);
+			if (err)
+				return err;
+			break;
+		default:
+			erofs_err(sb, "Unrecognized mount option \"%s\" or missing value", p);
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+
+#ifdef CONFIG_EROFS_FS_ZIP
+static const struct address_space_operations managed_cache_aops;
+
+static int erofs_managed_cache_releasepage(struct page *page, gfp_t gfp_mask)
+{
+	int ret = 1;	/* 0 - busy */
+	struct address_space *const mapping = page->mapping;
+
+	DBG_BUGON(!PageLocked(page));
+	DBG_BUGON(mapping->a_ops != &managed_cache_aops);
+
+	if (PagePrivate(page))
+		ret = erofs_try_to_free_cached_page(mapping, page);
+
+	return ret;
+}
+
+static void erofs_managed_cache_invalidatepage(struct page *page,
+					       unsigned int offset,
+					       unsigned int length)
+{
+	const unsigned int stop = length + offset;
+
+	DBG_BUGON(!PageLocked(page));
+
+	/* Check for potential overflow in debug mode */
+	DBG_BUGON(stop > PAGE_SIZE || stop < length);
+
+	if (offset == 0 && stop == PAGE_SIZE)
+		while (!erofs_managed_cache_releasepage(page, GFP_NOFS))
+			cond_resched();
+}
+
+static const struct address_space_operations managed_cache_aops = {
+	.releasepage = erofs_managed_cache_releasepage,
+	.invalidatepage = erofs_managed_cache_invalidatepage,
+};
+
+static int erofs_init_managed_cache(struct super_block *sb)
+{
+	struct erofs_sb_info *const sbi = EROFS_SB(sb);
+	struct inode *const inode = new_inode(sb);
+
+	if (!inode)
+		return -ENOMEM;
+
+	set_nlink(inode, 1);
+	inode->i_size = OFFSET_MAX;
+
+	inode->i_mapping->a_ops = &managed_cache_aops;
+	mapping_set_gfp_mask(inode->i_mapping,
+			     GFP_NOFS | __GFP_HIGHMEM | __GFP_MOVABLE);
+	sbi->managed_cache = inode;
+	return 0;
+}
+#else
+static int erofs_init_managed_cache(struct super_block *sb) { return 0; }
+#endif
+
+static int erofs_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct inode *inode;
+	struct erofs_sb_info *sbi;
+	int err;
+
+	sb->s_magic = EROFS_SUPER_MAGIC;
+
+	if (!sb_set_blocksize(sb, EROFS_BLKSIZ)) {
+		erofs_err(sb, "failed to set erofs blksize");
+		return -EINVAL;
+	}
+
+	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
+	if (!sbi)
+		return -ENOMEM;
+
+	sb->s_fs_info = sbi;
+	err = erofs_read_superblock(sb);
+	if (err)
+		return err;
+
+	sb->s_flags |= SB_RDONLY | SB_NOATIME;
+	sb->s_maxbytes = MAX_LFS_FILESIZE;
+	sb->s_time_gran = 1;
+
+	sb->s_op = &erofs_sops;
+
+#ifdef CONFIG_EROFS_FS_XATTR
+	sb->s_xattr = erofs_xattr_handlers;
+#endif
+	/* set erofs default mount options */
+	erofs_default_options(sbi);
+
+	err = erofs_parse_options(sb, data);
+	if (err)
+		return err;
+
+	if (test_opt(sbi, POSIX_ACL))
+		sb->s_flags |= SB_POSIXACL;
+	else
+		sb->s_flags &= ~SB_POSIXACL;
+
+#ifdef CONFIG_EROFS_FS_ZIP
+	INIT_RADIX_TREE(&sbi->workstn_tree, GFP_ATOMIC);
+#endif
+
+	/* get the root inode */
+	inode = erofs_iget(sb, ROOT_NID(sbi), true);
+	if (IS_ERR(inode))
+		return PTR_ERR(inode);
+
+	if (!S_ISDIR(inode->i_mode)) {
+		erofs_err(sb, "rootino(nid %llu) is not a directory(i_mode %o)",
+			  ROOT_NID(sbi), inode->i_mode);
+		iput(inode);
+		return -EINVAL;
+	}
+
+	sb->s_root = d_make_root(inode);
+	if (!sb->s_root)
+		return -ENOMEM;
+
+	erofs_shrinker_register(sb);
+	/* sb->s_umount is already locked, SB_ACTIVE and SB_BORN are not set */
+	err = erofs_init_managed_cache(sb);
+	if (err)
+		return err;
+
+	erofs_info(sb, "mounted with opts: %s, root inode @ nid %llu.",
+		   (char *)data, ROOT_NID(sbi));
+	return 0;
+}
+
+static struct dentry *erofs_mount(struct file_system_type *fs_type, int flags,
+				  const char *dev_name, void *data)
+{
+	return mount_bdev(fs_type, flags, dev_name, data, erofs_fill_super);
+}
+
+/*
+ * could be triggered after deactivate_locked_super()
+ * is called, thus including umount and failed to initialize.
+ */
+static void erofs_kill_sb(struct super_block *sb)
+{
+	struct erofs_sb_info *sbi;
+
+	WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC);
+
+	kill_block_super(sb);
+
+	sbi = EROFS_SB(sb);
+	if (!sbi)
+		return;
+	kfree(sbi);
+	sb->s_fs_info = NULL;
+}
+
+/* called when ->s_root is non-NULL */
+static void erofs_put_super(struct super_block *sb)
+{
+	struct erofs_sb_info *const sbi = EROFS_SB(sb);
+
+	DBG_BUGON(!sbi);
+
+	erofs_shrinker_unregister(sb);
+#ifdef CONFIG_EROFS_FS_ZIP
+	iput(sbi->managed_cache);
+	sbi->managed_cache = NULL;
+#endif
+}
+
+static struct file_system_type erofs_fs_type = {
+	.owner          = THIS_MODULE,
+	.name           = "erofs",
+	.mount          = erofs_mount,
+	.kill_sb        = erofs_kill_sb,
+	.fs_flags       = FS_REQUIRES_DEV,
+};
+MODULE_ALIAS_FS("erofs");
+
+static int __init erofs_module_init(void)
+{
+	int err;
+
+	erofs_check_ondisk_layout_definitions();
+
+	erofs_inode_cachep = kmem_cache_create("erofs_inode",
+					       sizeof(struct erofs_inode), 0,
+					       SLAB_RECLAIM_ACCOUNT,
+					       erofs_inode_init_once);
+	if (!erofs_inode_cachep) {
+		err = -ENOMEM;
+		goto icache_err;
+	}
+
+	err = erofs_init_shrinker();
+	if (err)
+		goto shrinker_err;
+
+	err = z_erofs_init_zip_subsystem();
+	if (err)
+		goto zip_err;
+
+	err = register_filesystem(&erofs_fs_type);
+	if (err)
+		goto fs_err;
+
+	return 0;
+
+fs_err:
+	z_erofs_exit_zip_subsystem();
+zip_err:
+	erofs_exit_shrinker();
+shrinker_err:
+	kmem_cache_destroy(erofs_inode_cachep);
+icache_err:
+	return err;
+}
+
+static void __exit erofs_module_exit(void)
+{
+	unregister_filesystem(&erofs_fs_type);
+	z_erofs_exit_zip_subsystem();
+	erofs_exit_shrinker();
+
+	/* Ensure all RCU free inodes are safe before cache is destroyed. */
+	rcu_barrier();
+	kmem_cache_destroy(erofs_inode_cachep);
+}
+
+/* get filesystem statistics */
+static int erofs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	struct super_block *sb = dentry->d_sb;
+	struct erofs_sb_info *sbi = EROFS_SB(sb);
+	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
+
+	buf->f_type = sb->s_magic;
+	buf->f_bsize = EROFS_BLKSIZ;
+	buf->f_blocks = sbi->blocks;
+	buf->f_bfree = buf->f_bavail = 0;
+
+	buf->f_files = ULLONG_MAX;
+	buf->f_ffree = ULLONG_MAX - sbi->inos;
+
+	buf->f_namelen = EROFS_NAME_LEN;
+
+	buf->f_fsid.val[0] = (u32)id;
+	buf->f_fsid.val[1] = (u32)(id >> 32);
+	return 0;
+}
+
+static int erofs_show_options(struct seq_file *seq, struct dentry *root)
+{
+	struct erofs_sb_info *sbi __maybe_unused = EROFS_SB(root->d_sb);
+
+#ifdef CONFIG_EROFS_FS_XATTR
+	if (test_opt(sbi, XATTR_USER))
+		seq_puts(seq, ",user_xattr");
+	else
+		seq_puts(seq, ",nouser_xattr");
+#endif
+#ifdef CONFIG_EROFS_FS_POSIX_ACL
+	if (test_opt(sbi, POSIX_ACL))
+		seq_puts(seq, ",acl");
+	else
+		seq_puts(seq, ",noacl");
+#endif
+#ifdef CONFIG_EROFS_FS_ZIP
+	if (sbi->cache_strategy == EROFS_ZIP_CACHE_DISABLED) {
+		seq_puts(seq, ",cache_strategy=disabled");
+	} else if (sbi->cache_strategy == EROFS_ZIP_CACHE_READAHEAD) {
+		seq_puts(seq, ",cache_strategy=readahead");
+	} else if (sbi->cache_strategy == EROFS_ZIP_CACHE_READAROUND) {
+		seq_puts(seq, ",cache_strategy=readaround");
+	} else {
+		seq_puts(seq, ",cache_strategy=(unknown)");
+		DBG_BUGON(1);
+	}
+#endif
+	return 0;
+}
+
+static int erofs_remount(struct super_block *sb, int *flags, char *data)
+{
+	struct erofs_sb_info *sbi = EROFS_SB(sb);
+	unsigned int org_mnt_opt = sbi->mount_opt;
+	int err;
+
+	DBG_BUGON(!sb_rdonly(sb));
+	err = erofs_parse_options(sb, data);
+	if (err)
+		goto out;
+
+	if (test_opt(sbi, POSIX_ACL))
+		sb->s_flags |= SB_POSIXACL;
+	else
+		sb->s_flags &= ~SB_POSIXACL;
+
+	*flags |= SB_RDONLY;
+	return 0;
+out:
+	sbi->mount_opt = org_mnt_opt;
+	return err;
+}
+
+const struct super_operations erofs_sops = {
+	.put_super = erofs_put_super,
+	.alloc_inode = erofs_alloc_inode,
+	.free_inode = erofs_free_inode,
+	.statfs = erofs_statfs,
+	.show_options = erofs_show_options,
+	.remount_fs = erofs_remount,
+};
+
+module_init(erofs_module_init);
+module_exit(erofs_module_exit);
+
+MODULE_DESCRIPTION("Enhanced ROM File System");
+MODULE_AUTHOR("Gao Xiang, Chao Yu, Miao Xie, CONSUMER BG, HUAWEI Inc.");
+MODULE_LICENSE("GPL");
+