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![Arjan van de Ven](/assets/img/avatar_default.png)
Many struct inode_operations in the kernel can be "const". Marking them const moves these to the .rodata section, which avoids false sharing with potential dirty data. In addition it'll catch accidental writes at compile time to these shared resources. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
222 lines
4.9 KiB
C
222 lines
4.9 KiB
C
/*
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FUSE: Filesystem in Userspace
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Copyright (C) 2001-2006 Miklos Szeredi <miklos@szeredi.hu>
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This program can be distributed under the terms of the GNU GPL.
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See the file COPYING.
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*/
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#include "fuse_i.h"
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#include <linux/init.h>
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#include <linux/module.h>
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#define FUSE_CTL_SUPER_MAGIC 0x65735543
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/*
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* This is non-NULL when the single instance of the control filesystem
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* exists. Protected by fuse_mutex
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*/
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static struct super_block *fuse_control_sb;
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static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file)
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{
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struct fuse_conn *fc;
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mutex_lock(&fuse_mutex);
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fc = file->f_path.dentry->d_inode->i_private;
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if (fc)
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fc = fuse_conn_get(fc);
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mutex_unlock(&fuse_mutex);
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return fc;
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}
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static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
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if (fc) {
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fuse_abort_conn(fc);
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fuse_conn_put(fc);
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}
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return count;
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}
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static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf,
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size_t len, loff_t *ppos)
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{
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char tmp[32];
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size_t size;
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if (!*ppos) {
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struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
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if (!fc)
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return 0;
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file->private_data=(void *)(long)atomic_read(&fc->num_waiting);
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fuse_conn_put(fc);
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}
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size = sprintf(tmp, "%ld\n", (long)file->private_data);
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return simple_read_from_buffer(buf, len, ppos, tmp, size);
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}
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static const struct file_operations fuse_ctl_abort_ops = {
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.open = nonseekable_open,
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.write = fuse_conn_abort_write,
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};
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static const struct file_operations fuse_ctl_waiting_ops = {
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.open = nonseekable_open,
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.read = fuse_conn_waiting_read,
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};
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static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
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struct fuse_conn *fc,
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const char *name,
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int mode, int nlink,
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const struct inode_operations *iop,
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const struct file_operations *fop)
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{
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struct dentry *dentry;
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struct inode *inode;
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BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
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dentry = d_alloc_name(parent, name);
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if (!dentry)
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return NULL;
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fc->ctl_dentry[fc->ctl_ndents++] = dentry;
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inode = new_inode(fuse_control_sb);
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if (!inode)
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return NULL;
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inode->i_mode = mode;
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inode->i_uid = fc->user_id;
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inode->i_gid = fc->group_id;
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inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
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/* setting ->i_op to NULL is not allowed */
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if (iop)
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inode->i_op = iop;
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inode->i_fop = fop;
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inode->i_nlink = nlink;
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inode->i_private = fc;
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d_add(dentry, inode);
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return dentry;
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}
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/*
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* Add a connection to the control filesystem (if it exists). Caller
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* must hold fuse_mutex
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*/
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int fuse_ctl_add_conn(struct fuse_conn *fc)
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{
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struct dentry *parent;
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char name[32];
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if (!fuse_control_sb)
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return 0;
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parent = fuse_control_sb->s_root;
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inc_nlink(parent->d_inode);
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sprintf(name, "%llu", (unsigned long long) fc->id);
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parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
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&simple_dir_inode_operations,
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&simple_dir_operations);
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if (!parent)
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goto err;
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if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
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NULL, &fuse_ctl_waiting_ops) ||
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!fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
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NULL, &fuse_ctl_abort_ops))
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goto err;
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return 0;
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err:
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fuse_ctl_remove_conn(fc);
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return -ENOMEM;
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}
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/*
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* Remove a connection from the control filesystem (if it exists).
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* Caller must hold fuse_mutex
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*/
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void fuse_ctl_remove_conn(struct fuse_conn *fc)
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{
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int i;
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if (!fuse_control_sb)
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return;
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for (i = fc->ctl_ndents - 1; i >= 0; i--) {
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struct dentry *dentry = fc->ctl_dentry[i];
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dentry->d_inode->i_private = NULL;
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d_drop(dentry);
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dput(dentry);
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}
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fuse_control_sb->s_root->d_inode->i_nlink--;
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}
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static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent)
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{
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struct tree_descr empty_descr = {""};
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struct fuse_conn *fc;
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int err;
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err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
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if (err)
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return err;
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mutex_lock(&fuse_mutex);
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BUG_ON(fuse_control_sb);
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fuse_control_sb = sb;
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list_for_each_entry(fc, &fuse_conn_list, entry) {
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err = fuse_ctl_add_conn(fc);
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if (err) {
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fuse_control_sb = NULL;
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mutex_unlock(&fuse_mutex);
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return err;
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}
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}
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mutex_unlock(&fuse_mutex);
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return 0;
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}
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static int fuse_ctl_get_sb(struct file_system_type *fs_type, int flags,
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const char *dev_name, void *raw_data,
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struct vfsmount *mnt)
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{
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return get_sb_single(fs_type, flags, raw_data,
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fuse_ctl_fill_super, mnt);
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}
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static void fuse_ctl_kill_sb(struct super_block *sb)
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{
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struct fuse_conn *fc;
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mutex_lock(&fuse_mutex);
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fuse_control_sb = NULL;
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list_for_each_entry(fc, &fuse_conn_list, entry)
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fc->ctl_ndents = 0;
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mutex_unlock(&fuse_mutex);
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kill_litter_super(sb);
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}
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static struct file_system_type fuse_ctl_fs_type = {
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.owner = THIS_MODULE,
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.name = "fusectl",
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.get_sb = fuse_ctl_get_sb,
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.kill_sb = fuse_ctl_kill_sb,
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};
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int __init fuse_ctl_init(void)
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{
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return register_filesystem(&fuse_ctl_fs_type);
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}
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void fuse_ctl_cleanup(void)
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{
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unregister_filesystem(&fuse_ctl_fs_type);
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}
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