mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-22 20:23:57 +08:00
99829b8329
Building on the previous change to anon_inode_getfd, this patch introduces support for handling of O_NONBLOCK in addition to the already supported O_CLOEXEC. Following patches will take advantage of this support. As can be seen, the additional support for supporting this functionality is minimal. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Acked-by: Davide Libenzi <davidel@xmailserver.org> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
193 lines
4.9 KiB
C
193 lines
4.9 KiB
C
/*
|
|
* fs/anon_inodes.c
|
|
*
|
|
* Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org>
|
|
*
|
|
* Thanks to Arnd Bergmann for code review and suggestions.
|
|
* More changes for Thomas Gleixner suggestions.
|
|
*
|
|
*/
|
|
|
|
#include <linux/file.h>
|
|
#include <linux/poll.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/init.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/module.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/magic.h>
|
|
#include <linux/anon_inodes.h>
|
|
|
|
#include <asm/uaccess.h>
|
|
|
|
static struct vfsmount *anon_inode_mnt __read_mostly;
|
|
static struct inode *anon_inode_inode;
|
|
static const struct file_operations anon_inode_fops;
|
|
|
|
static int anon_inodefs_get_sb(struct file_system_type *fs_type, int flags,
|
|
const char *dev_name, void *data,
|
|
struct vfsmount *mnt)
|
|
{
|
|
return get_sb_pseudo(fs_type, "anon_inode:", NULL, ANON_INODE_FS_MAGIC,
|
|
mnt);
|
|
}
|
|
|
|
static int anon_inodefs_delete_dentry(struct dentry *dentry)
|
|
{
|
|
/*
|
|
* We faked vfs to believe the dentry was hashed when we created it.
|
|
* Now we restore the flag so that dput() will work correctly.
|
|
*/
|
|
dentry->d_flags |= DCACHE_UNHASHED;
|
|
return 1;
|
|
}
|
|
|
|
static struct file_system_type anon_inode_fs_type = {
|
|
.name = "anon_inodefs",
|
|
.get_sb = anon_inodefs_get_sb,
|
|
.kill_sb = kill_anon_super,
|
|
};
|
|
static struct dentry_operations anon_inodefs_dentry_operations = {
|
|
.d_delete = anon_inodefs_delete_dentry,
|
|
};
|
|
|
|
/**
|
|
* anon_inode_getfd - creates a new file instance by hooking it up to an
|
|
* anonymous inode, and a dentry that describe the "class"
|
|
* of the file
|
|
*
|
|
* @name: [in] name of the "class" of the new file
|
|
* @fops: [in] file operations for the new file
|
|
* @priv: [in] private data for the new file (will be file's private_data)
|
|
* @flags: [in] flags
|
|
*
|
|
* Creates a new file by hooking it on a single inode. This is useful for files
|
|
* that do not need to have a full-fledged inode in order to operate correctly.
|
|
* All the files created with anon_inode_getfd() will share a single inode,
|
|
* hence saving memory and avoiding code duplication for the file/inode/dentry
|
|
* setup. Returns new descriptor or -error.
|
|
*/
|
|
int anon_inode_getfd(const char *name, const struct file_operations *fops,
|
|
void *priv, int flags)
|
|
{
|
|
struct qstr this;
|
|
struct dentry *dentry;
|
|
struct file *file;
|
|
int error, fd;
|
|
|
|
if (IS_ERR(anon_inode_inode))
|
|
return -ENODEV;
|
|
|
|
error = get_unused_fd_flags(flags);
|
|
if (error < 0)
|
|
return error;
|
|
fd = error;
|
|
|
|
/*
|
|
* Link the inode to a directory entry by creating a unique name
|
|
* using the inode sequence number.
|
|
*/
|
|
error = -ENOMEM;
|
|
this.name = name;
|
|
this.len = strlen(name);
|
|
this.hash = 0;
|
|
dentry = d_alloc(anon_inode_mnt->mnt_sb->s_root, &this);
|
|
if (!dentry)
|
|
goto err_put_unused_fd;
|
|
|
|
/*
|
|
* We know the anon_inode inode count is always greater than zero,
|
|
* so we can avoid doing an igrab() and we can use an open-coded
|
|
* atomic_inc().
|
|
*/
|
|
atomic_inc(&anon_inode_inode->i_count);
|
|
|
|
dentry->d_op = &anon_inodefs_dentry_operations;
|
|
/* Do not publish this dentry inside the global dentry hash table */
|
|
dentry->d_flags &= ~DCACHE_UNHASHED;
|
|
d_instantiate(dentry, anon_inode_inode);
|
|
|
|
error = -ENFILE;
|
|
file = alloc_file(anon_inode_mnt, dentry,
|
|
FMODE_READ | FMODE_WRITE, fops);
|
|
if (!file)
|
|
goto err_dput;
|
|
file->f_mapping = anon_inode_inode->i_mapping;
|
|
|
|
file->f_pos = 0;
|
|
file->f_flags = O_RDWR | (flags & O_NONBLOCK);
|
|
file->f_version = 0;
|
|
file->private_data = priv;
|
|
|
|
fd_install(fd, file);
|
|
|
|
return fd;
|
|
|
|
err_dput:
|
|
dput(dentry);
|
|
err_put_unused_fd:
|
|
put_unused_fd(fd);
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL_GPL(anon_inode_getfd);
|
|
|
|
/*
|
|
* A single inode exists for all anon_inode files. Contrary to pipes,
|
|
* anon_inode inodes have no associated per-instance data, so we need
|
|
* only allocate one of them.
|
|
*/
|
|
static struct inode *anon_inode_mkinode(void)
|
|
{
|
|
struct inode *inode = new_inode(anon_inode_mnt->mnt_sb);
|
|
|
|
if (!inode)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
inode->i_fop = &anon_inode_fops;
|
|
|
|
/*
|
|
* Mark the inode dirty from the very beginning,
|
|
* that way it will never be moved to the dirty
|
|
* list because mark_inode_dirty() will think
|
|
* that it already _is_ on the dirty list.
|
|
*/
|
|
inode->i_state = I_DIRTY;
|
|
inode->i_mode = S_IRUSR | S_IWUSR;
|
|
inode->i_uid = current->fsuid;
|
|
inode->i_gid = current->fsgid;
|
|
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
|
|
return inode;
|
|
}
|
|
|
|
static int __init anon_inode_init(void)
|
|
{
|
|
int error;
|
|
|
|
error = register_filesystem(&anon_inode_fs_type);
|
|
if (error)
|
|
goto err_exit;
|
|
anon_inode_mnt = kern_mount(&anon_inode_fs_type);
|
|
if (IS_ERR(anon_inode_mnt)) {
|
|
error = PTR_ERR(anon_inode_mnt);
|
|
goto err_unregister_filesystem;
|
|
}
|
|
anon_inode_inode = anon_inode_mkinode();
|
|
if (IS_ERR(anon_inode_inode)) {
|
|
error = PTR_ERR(anon_inode_inode);
|
|
goto err_mntput;
|
|
}
|
|
|
|
return 0;
|
|
|
|
err_mntput:
|
|
mntput(anon_inode_mnt);
|
|
err_unregister_filesystem:
|
|
unregister_filesystem(&anon_inode_fs_type);
|
|
err_exit:
|
|
panic(KERN_ERR "anon_inode_init() failed (%d)\n", error);
|
|
}
|
|
|
|
fs_initcall(anon_inode_init);
|
|
|