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Subject[PATCH 03/25] staging: erofs: add super block operations
Date
This commit adds erofs super block operations, including (u)mount,
remount_fs, show_options, statfs, in addition to some private
icache management functions.

Signed-off-by: Miao Xie <miaoxie@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
drivers/staging/erofs/super.c | 415 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 415 insertions(+)
create mode 100644 drivers/staging/erofs/super.c

diff --git a/drivers/staging/erofs/super.c b/drivers/staging/erofs/super.c
new file mode 100644
index 0000000..98ae03d
--- /dev/null
+++ b/drivers/staging/erofs/super.c
@@ -0,0 +1,415 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/drivers/staging/erofs/super.c
+ *
+ * Copyright (C) 2017-2018 HUAWEI, Inc.
+ * http://www.huawei.com/
+ * Created by Gao Xiang <gaoxiang25@huawei.com>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+#include <linux/module.h>
+#include <linux/buffer_head.h>
+#include <linux/statfs.h>
+#include <linux/parser.h>
+#include "internal.h"
+
+static struct kmem_cache *erofs_inode_cachep __read_mostly;
+
+static void init_once(void *ptr)
+{
+ struct erofs_vnode *vi = ptr;
+
+ inode_init_once(&vi->vfs_inode);
+}
+
+static int erofs_init_inode_cache(void)
+{
+ erofs_inode_cachep = kmem_cache_create("erofs_inode",
+ sizeof(struct erofs_vnode), 0,
+ SLAB_RECLAIM_ACCOUNT, init_once);
+
+ return erofs_inode_cachep != NULL ? 0 : -ENOMEM;
+}
+
+static void erofs_exit_inode_cache(void)
+{
+ BUG_ON(erofs_inode_cachep == NULL);
+ kmem_cache_destroy(erofs_inode_cachep);
+}
+
+static struct inode *alloc_inode(struct super_block *sb)
+{
+ struct erofs_vnode *vi =
+ kmem_cache_alloc(erofs_inode_cachep, GFP_KERNEL);
+
+ if (vi == NULL)
+ return NULL;
+
+ /* zero out everything except vfs_inode */
+ memset(vi, 0, offsetof(struct erofs_vnode, vfs_inode));
+ return &vi->vfs_inode;
+}
+
+static void i_callback(struct rcu_head *head)
+{
+ struct inode *inode = container_of(head, struct inode, i_rcu);
+ struct erofs_vnode *vi = EROFS_V(inode);
+
+ /* be careful RCU symlink path (see ext4_inode_info->i_data)! */
+ if (is_inode_fast_symlink(inode))
+ kfree(inode->i_link);
+
+ kfree(vi->xattr_shared_xattrs);
+
+ kmem_cache_free(erofs_inode_cachep, vi);
+}
+
+static void destroy_inode(struct inode *inode)
+{
+ call_rcu(&inode->i_rcu, i_callback);
+}
+
+static int superblock_read(struct super_block *sb)
+{
+ struct erofs_sb_info *sbi;
+ struct buffer_head *bh;
+ struct erofs_super_block *layout;
+ unsigned blkszbits;
+ int ret;
+
+ bh = sb_bread(sb, 0);
+
+ if (bh == NULL) {
+ errln("cannot read erofs superblock");
+ return -EIO;
+ }
+
+ sbi = EROFS_SB(sb);
+ layout = (struct erofs_super_block *)((u8 *)bh->b_data
+ + EROFS_SUPER_OFFSET);
+
+ ret = -EINVAL;
+ if (le32_to_cpu(layout->magic) != EROFS_SUPER_MAGIC_V1) {
+ errln("cannot find valid erofs superblock");
+ goto out;
+ }
+
+ blkszbits = layout->blkszbits;
+ /* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */
+ if (unlikely(blkszbits != LOG_BLOCK_SIZE)) {
+ errln("blksize %u isn't supported on this platform",
+ 1 << blkszbits);
+ goto out;
+ }
+
+ sbi->blocks = le32_to_cpu(layout->blocks);
+ sbi->meta_blkaddr = le32_to_cpu(layout->meta_blkaddr);
+ sbi->islotbits = ffs(sizeof(struct erofs_inode_v1)) - 1;
+
+ sbi->root_nid = le16_to_cpu(layout->root_nid);
+ sbi->inos = le64_to_cpu(layout->inos);
+
+ sbi->build_time = le64_to_cpu(layout->build_time);
+ sbi->build_time_nsec = le32_to_cpu(layout->build_time_nsec);
+
+ memcpy(&sb->s_uuid, layout->uuid, sizeof(layout->uuid));
+ memcpy(sbi->volume_name, layout->volume_name,
+ sizeof(layout->volume_name));
+
+ ret = 0;
+out:
+ brelse(bh);
+ return ret;
+}
+
+static void default_options(struct erofs_sb_info *sbi)
+{
+}
+
+enum {
+ Opt_err
+};
+
+static match_table_t erofs_tokens = {
+ {Opt_err, NULL}
+};
+
+static int parse_options(struct super_block *sb, char *options)
+{
+ substring_t args[MAX_OPT_ARGS];
+ char *p;
+
+ if (!options)
+ return 0;
+
+ while ((p = strsep(&options, ",")) != NULL) {
+ int token;
+
+ if (!*p)
+ continue;
+
+ args[0].to = args[0].from = NULL;
+ token = match_token(p, erofs_tokens, args);
+
+ switch (token) {
+ default:
+ errln("Unrecognized mount option \"%s\" "
+ "or missing value", p);
+ return -EINVAL;
+ }
+ }
+ return 0;
+}
+
+static int erofs_read_super(struct super_block *sb,
+ const char *dev_name, void *data, int silent)
+{
+ struct inode *inode;
+ struct erofs_sb_info *sbi;
+ int err = -EINVAL;
+
+ infoln("read_super, device -> %s", dev_name);
+ infoln("options -> %s", (char *)data);
+
+ if (unlikely(!sb_set_blocksize(sb, EROFS_BLKSIZ))) {
+ errln("failed to set erofs blksize");
+ goto err;
+ }
+
+ sbi = kzalloc(sizeof(struct erofs_sb_info), GFP_KERNEL);
+ if (unlikely(sbi == NULL)) {
+ err = -ENOMEM;
+ goto err;
+ }
+ sb->s_fs_info = sbi;
+
+ err = superblock_read(sb);
+ if (err)
+ goto err_sbread;
+
+ sb->s_magic = EROFS_SUPER_MAGIC;
+ sb->s_flags |= MS_RDONLY | MS_NOATIME;
+ sb->s_maxbytes = MAX_LFS_FILESIZE;
+ sb->s_time_gran = 1;
+
+ sb->s_op = &erofs_sops;
+
+ /* set erofs default mount options */
+ default_options(sbi);
+
+ err = parse_options(sb, data);
+ if (err)
+ goto err_parseopt;
+
+ if (!silent)
+ infoln("root inode @ nid %llu", ROOT_NID(sbi));
+
+ /* get the root inode */
+ inode = erofs_iget(sb, ROOT_NID(sbi), true);
+ if (IS_ERR(inode)) {
+ err = PTR_ERR(inode);
+ goto err_iget;
+ }
+
+ if (!S_ISDIR(inode->i_mode)) {
+ errln("rootino(nid %llu) is not a directory(i_mode %o)",
+ ROOT_NID(sbi), inode->i_mode);
+ err = -EINVAL;
+ goto err_isdir;
+ }
+
+ sb->s_root = d_make_root(inode);
+ if (sb->s_root == NULL) {
+ err = -ENOMEM;
+ goto err_makeroot;
+ }
+
+ /* save the device name to sbi */
+ sbi->dev_name = __getname();
+ if (sbi->dev_name == NULL) {
+ err = -ENOMEM;
+ goto err_devname;
+ }
+
+ snprintf(sbi->dev_name, PATH_MAX, "%s", dev_name);
+ sbi->dev_name[PATH_MAX - 1] = '\0';
+
+ /*
+ * We already have a positive dentry, which was instantiated
+ * by d_make_root. Just need to d_rehash it.
+ */
+ d_rehash(sb->s_root);
+
+ if (!silent)
+ infoln("mounted on %s with opts: %s.", dev_name,
+ (char *)data);
+ return 0;
+ /*
+ * please add a label for each exit point and use
+ * the following name convention, thus new features
+ * can be integrated easily without renaming labels.
+ */
+err_devname:
+ dput(sb->s_root);
+err_makeroot:
+err_isdir:
+ if (sb->s_root == NULL)
+ iput(inode);
+err_iget:
+err_parseopt:
+err_sbread:
+ sb->s_fs_info = NULL;
+ kfree(sbi);
+err:
+ return err;
+}
+
+/*
+ * could be triggered after deactivate_locked_super()
+ * is called, thus including umount and failed to initialize.
+ */
+static void erofs_put_super(struct super_block *sb)
+{
+ struct erofs_sb_info *sbi = EROFS_SB(sb);
+
+ /* for cases which are failed in "read_super" */
+ if (sbi == NULL)
+ return;
+
+ WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC);
+
+ infoln("unmounted for %s", sbi->dev_name);
+ __putname(sbi->dev_name);
+
+ kfree(sbi);
+ sb->s_fs_info = NULL;
+}
+
+
+struct erofs_mount_private {
+ const char *dev_name;
+ char *options;
+};
+
+/* support mount_bdev() with options */
+static int erofs_fill_super(struct super_block *sb,
+ void *_priv, int silent)
+{
+ struct erofs_mount_private *priv = _priv;
+
+ return erofs_read_super(sb, priv->dev_name,
+ priv->options, silent);
+}
+
+static struct dentry *erofs_mount(
+ struct file_system_type *fs_type, int flags,
+ const char *dev_name, void *data)
+{
+ struct erofs_mount_private priv = {
+ .dev_name = dev_name,
+ .options = data
+ };
+
+ return mount_bdev(fs_type, flags, dev_name,
+ &priv, erofs_fill_super);
+}
+
+static void erofs_kill_sb(struct super_block *sb)
+{
+ kill_block_super(sb);
+}
+
+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();
+ infoln("initializing erofs " EROFS_VERSION);
+
+ err = erofs_init_inode_cache();
+ if (err)
+ goto icache_err;
+
+ err = register_filesystem(&erofs_fs_type);
+ if (err)
+ goto fs_err;
+
+ infoln("successfully to initialize erofs");
+ return 0;
+
+fs_err:
+ erofs_exit_inode_cache();
+icache_err:
+ return err;
+}
+
+static void __exit erofs_module_exit(void)
+{
+ unregister_filesystem(&erofs_fs_type);
+ erofs_exit_inode_cache();
+ infoln("successfully finalize erofs");
+}
+
+/* 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)
+{
+ return 0;
+}
+
+static int erofs_remount(struct super_block *sb, int *flags, char *data)
+{
+ BUG_ON(!sb_rdonly(sb));
+
+ *flags |= MS_RDONLY;
+ return 0;
+}
+
+const struct super_operations erofs_sops = {
+ .put_super = erofs_put_super,
+ .alloc_inode = alloc_inode,
+ .destroy_inode = destroy_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, Yu Chao, Miao Xie, CONSUMER BG, HUAWEI Inc.");
+MODULE_LICENSE("GPL");
+
--
1.9.1
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