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![Jan Kara](/assets/img/avatar_default.png)
Currently we allocated anon_inode_inode in anon_inodefs_mount. This is somewhat fragile as if that function ever gets called again, it will overwrite anon_inode_inode pointer. So move the initialization of anon_inode_inode to anon_inode_init(). Signed-off-by: Jan Kara <jack@suse.cz> [ Further simplified on suggestion from Dave Jones ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
179 lines
4.9 KiB
C
179 lines
4.9 KiB
C
/*
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* fs/anon_inodes.c
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*
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* Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org>
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*
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* Thanks to Arnd Bergmann for code review and suggestions.
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* More changes for Thomas Gleixner suggestions.
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*
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*/
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#include <linux/cred.h>
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#include <linux/file.h>
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#include <linux/poll.h>
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#include <linux/sched.h>
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/mount.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/magic.h>
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#include <linux/anon_inodes.h>
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#include <asm/uaccess.h>
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static struct vfsmount *anon_inode_mnt __read_mostly;
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static struct inode *anon_inode_inode;
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/*
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* anon_inodefs_dname() is called from d_path().
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*/
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static char *anon_inodefs_dname(struct dentry *dentry, char *buffer, int buflen)
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{
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return dynamic_dname(dentry, buffer, buflen, "anon_inode:%s",
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dentry->d_name.name);
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}
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static const struct dentry_operations anon_inodefs_dentry_operations = {
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.d_dname = anon_inodefs_dname,
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};
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static struct dentry *anon_inodefs_mount(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data)
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{
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return mount_pseudo(fs_type, "anon_inode:", NULL,
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&anon_inodefs_dentry_operations, ANON_INODE_FS_MAGIC);
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}
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static struct file_system_type anon_inode_fs_type = {
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.name = "anon_inodefs",
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.mount = anon_inodefs_mount,
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.kill_sb = kill_anon_super,
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};
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/**
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* anon_inode_getfile - creates a new file instance by hooking it up to an
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* anonymous inode, and a dentry that describe the "class"
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* of the file
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*
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* @name: [in] name of the "class" of the new file
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* @fops: [in] file operations for the new file
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* @priv: [in] private data for the new file (will be file's private_data)
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* @flags: [in] flags
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*
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* Creates a new file by hooking it on a single inode. This is useful for files
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* that do not need to have a full-fledged inode in order to operate correctly.
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* All the files created with anon_inode_getfile() will share a single inode,
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* hence saving memory and avoiding code duplication for the file/inode/dentry
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* setup. Returns the newly created file* or an error pointer.
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*/
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struct file *anon_inode_getfile(const char *name,
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const struct file_operations *fops,
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void *priv, int flags)
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{
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struct qstr this;
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struct path path;
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struct file *file;
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if (IS_ERR(anon_inode_inode))
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return ERR_PTR(-ENODEV);
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if (fops->owner && !try_module_get(fops->owner))
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return ERR_PTR(-ENOENT);
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/*
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* Link the inode to a directory entry by creating a unique name
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* using the inode sequence number.
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*/
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file = ERR_PTR(-ENOMEM);
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this.name = name;
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this.len = strlen(name);
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this.hash = 0;
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path.dentry = d_alloc_pseudo(anon_inode_mnt->mnt_sb, &this);
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if (!path.dentry)
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goto err_module;
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path.mnt = mntget(anon_inode_mnt);
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/*
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* We know the anon_inode inode count is always greater than zero,
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* so ihold() is safe.
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*/
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ihold(anon_inode_inode);
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d_instantiate(path.dentry, anon_inode_inode);
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file = alloc_file(&path, OPEN_FMODE(flags), fops);
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if (IS_ERR(file))
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goto err_dput;
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file->f_mapping = anon_inode_inode->i_mapping;
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file->f_flags = flags & (O_ACCMODE | O_NONBLOCK);
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file->private_data = priv;
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return file;
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err_dput:
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path_put(&path);
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err_module:
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module_put(fops->owner);
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return file;
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}
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EXPORT_SYMBOL_GPL(anon_inode_getfile);
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/**
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* anon_inode_getfd - creates a new file instance by hooking it up to an
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* anonymous inode, and a dentry that describe the "class"
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* of the file
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*
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* @name: [in] name of the "class" of the new file
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* @fops: [in] file operations for the new file
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* @priv: [in] private data for the new file (will be file's private_data)
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* @flags: [in] flags
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*
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* Creates a new file by hooking it on a single inode. This is useful for files
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* that do not need to have a full-fledged inode in order to operate correctly.
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* All the files created with anon_inode_getfd() will share a single inode,
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* hence saving memory and avoiding code duplication for the file/inode/dentry
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* setup. Returns new descriptor or an error code.
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*/
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int anon_inode_getfd(const char *name, const struct file_operations *fops,
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void *priv, int flags)
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{
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int error, fd;
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struct file *file;
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error = get_unused_fd_flags(flags);
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if (error < 0)
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return error;
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fd = error;
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file = anon_inode_getfile(name, fops, priv, flags);
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if (IS_ERR(file)) {
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error = PTR_ERR(file);
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goto err_put_unused_fd;
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}
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fd_install(fd, file);
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return fd;
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err_put_unused_fd:
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put_unused_fd(fd);
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return error;
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}
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EXPORT_SYMBOL_GPL(anon_inode_getfd);
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static int __init anon_inode_init(void)
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{
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anon_inode_mnt = kern_mount(&anon_inode_fs_type);
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if (IS_ERR(anon_inode_mnt))
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panic("anon_inode_init() kernel mount failed (%ld)\n", PTR_ERR(anon_inode_mnt));
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anon_inode_inode = alloc_anon_inode(anon_inode_mnt->mnt_sb);
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if (IS_ERR(anon_inode_inode))
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panic("anon_inode_init() inode allocation failed (%ld)\n", PTR_ERR(anon_inode_inode));
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return 0;
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}
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fs_initcall(anon_inode_init);
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