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epoll: use anonymous inodes
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Cut out lots of code from epoll, by reusing the anonymous inode source
patch (fs/anon_inodes.c).

Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Davide Libenzi authored and Linus Torvalds committed May 11, 2007
1 parent 9c3060b commit da66f7c
Showing 1 changed file with 3 additions and 169 deletions.
172 changes: 3 additions & 169 deletions fs/eventpoll.c
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@
#include <linux/mount.h>
#include <linux/bitops.h>
#include <linux/mutex.h>
#include <linux/anon_inodes.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
Expand Down Expand Up @@ -75,8 +76,6 @@
*/


#define EVENTPOLLFS_MAGIC 0x03111965 /* My birthday should work for this :) */

#define DEBUG_EPOLL 0

#if DEBUG_EPOLL > 0
Expand Down Expand Up @@ -228,8 +227,6 @@ struct ep_pqueue {

static void ep_poll_safewake_init(struct poll_safewake *psw);
static void ep_poll_safewake(struct poll_safewake *psw, wait_queue_head_t *wq);
static int ep_getfd(int *efd, struct inode **einode, struct file **efile,
struct eventpoll *ep);
static int ep_alloc(struct eventpoll **pep);
static void ep_free(struct eventpoll *ep);
static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd);
Expand All @@ -255,11 +252,6 @@ static int ep_events_transfer(struct eventpoll *ep,
int maxevents);
static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
int maxevents, long timeout);
static int eventpollfs_delete_dentry(struct dentry *dentry);
static struct inode *ep_eventpoll_inode(void);
static int eventpollfs_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data, struct vfsmount *mnt);

/*
* This semaphore is used to serialize ep_free() and eventpoll_release_file().
Expand All @@ -275,30 +267,12 @@ static struct kmem_cache *epi_cache __read_mostly;
/* Slab cache used to allocate "struct eppoll_entry" */
static struct kmem_cache *pwq_cache __read_mostly;

/* Virtual fs used to allocate inodes for eventpoll files */
static struct vfsmount *eventpoll_mnt __read_mostly;

/* File callbacks that implement the eventpoll file behaviour */
static const struct file_operations eventpoll_fops = {
.release = ep_eventpoll_close,
.poll = ep_eventpoll_poll
};

/*
* This is used to register the virtual file system from where
* eventpoll inodes are allocated.
*/
static struct file_system_type eventpoll_fs_type = {
.name = "eventpollfs",
.get_sb = eventpollfs_get_sb,
.kill_sb = kill_anon_super,
};

/* Very basic directory entry operations for the eventpoll virtual file system */
static struct dentry_operations eventpollfs_dentry_operations = {
.d_delete = eventpollfs_delete_dentry,
};



/* Fast test to see if the file is an evenpoll file */
Expand Down Expand Up @@ -495,7 +469,8 @@ asmlinkage long sys_epoll_create(int size)
* Creates all the items needed to setup an eventpoll file. That is,
* a file structure, and inode and a free file descriptor.
*/
error = ep_getfd(&fd, &inode, &file, ep);
error = anon_inode_getfd(&fd, &inode, &file, "[eventpoll]",
&eventpoll_fops, ep);
if (error)
goto eexit_2;

Expand Down Expand Up @@ -725,82 +700,6 @@ asmlinkage long sys_epoll_pwait(int epfd, struct epoll_event __user *events,
#endif /* #ifdef TIF_RESTORE_SIGMASK */


/*
* Creates the file descriptor to be used by the epoll interface.
*/
static int ep_getfd(int *efd, struct inode **einode, struct file **efile,
struct eventpoll *ep)
{
struct qstr this;
char name[32];
struct dentry *dentry;
struct inode *inode;
struct file *file;
int error, fd;

/* Get an ready to use file */
error = -ENFILE;
file = get_empty_filp();
if (!file)
goto eexit_1;

/* Allocates an inode from the eventpoll file system */
inode = ep_eventpoll_inode();
if (IS_ERR(inode)) {
error = PTR_ERR(inode);
goto eexit_2;
}

/* Allocates a free descriptor to plug the file onto */
error = get_unused_fd();
if (error < 0)
goto eexit_3;
fd = error;

/*
* Link the inode to a directory entry by creating a unique name
* using the inode number.
*/
error = -ENOMEM;
sprintf(name, "[%lu]", inode->i_ino);
this.name = name;
this.len = strlen(name);
this.hash = inode->i_ino;
dentry = d_alloc(eventpoll_mnt->mnt_sb->s_root, &this);
if (!dentry)
goto eexit_4;
dentry->d_op = &eventpollfs_dentry_operations;
d_add(dentry, inode);
file->f_path.mnt = mntget(eventpoll_mnt);
file->f_path.dentry = dentry;
file->f_mapping = inode->i_mapping;

file->f_pos = 0;
file->f_flags = O_RDONLY;
file->f_op = &eventpoll_fops;
file->f_mode = FMODE_READ;
file->f_version = 0;
file->private_data = ep;

/* Install the new setup file into the allocated fd. */
fd_install(fd, file);

*efd = fd;
*einode = inode;
*efile = file;
return 0;

eexit_4:
put_unused_fd(fd);
eexit_3:
iput(inode);
eexit_2:
put_filp(file);
eexit_1:
return error;
}


static int ep_alloc(struct eventpoll **pep)
{
struct eventpoll *ep = kzalloc(sizeof(*ep), GFP_KERNEL);
Expand Down Expand Up @@ -1553,52 +1452,8 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
return res;
}

static int eventpollfs_delete_dentry(struct dentry *dentry)
{

return 1;
}

static struct inode *ep_eventpoll_inode(void)
{
int error = -ENOMEM;
struct inode *inode = new_inode(eventpoll_mnt->mnt_sb);

if (!inode)
goto eexit_1;

inode->i_fop = &eventpoll_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;

eexit_1:
return ERR_PTR(error);
}

static int
eventpollfs_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, "eventpoll:", NULL, EVENTPOLLFS_MAGIC,
mnt);
}


static int __init eventpoll_init(void)
{
int error;

mutex_init(&epmutex);

/* Initialize the structure used to perform safe poll wait head wake ups */
Expand All @@ -1614,34 +1469,13 @@ static int __init eventpoll_init(void)
sizeof(struct eppoll_entry), 0,
EPI_SLAB_DEBUG|SLAB_PANIC, NULL, NULL);

/*
* Register the virtual file system that will be the source of inodes
* for the eventpoll files
*/
error = register_filesystem(&eventpoll_fs_type);
if (error)
goto epanic;

/* Mount the above commented virtual file system */
eventpoll_mnt = kern_mount(&eventpoll_fs_type);
error = PTR_ERR(eventpoll_mnt);
if (IS_ERR(eventpoll_mnt))
goto epanic;

DNPRINTK(3, (KERN_INFO "[%p] eventpoll: successfully initialized.\n",
current));
return 0;

epanic:
panic("eventpoll_init() failed\n");
}


static void __exit eventpoll_exit(void)
{
/* Undo all operations done inside eventpoll_init() */
unregister_filesystem(&eventpoll_fs_type);
mntput(eventpoll_mnt);
kmem_cache_destroy(pwq_cache);
kmem_cache_destroy(epi_cache);
}
Expand Down

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