• Robert Love's avatar
    [PATCH] inotify · 0eeca283
    Robert Love authored
    
    inotify is intended to correct the deficiencies of dnotify, particularly
    its inability to scale and its terrible user interface:
    
            * dnotify requires the opening of one fd per each directory
              that you intend to watch. This quickly results in too many
              open files and pins removable media, preventing unmount.
            * dnotify is directory-based. You only learn about changes to
              directories. Sure, a change to a file in a directory affects
              the directory, but you are then forced to keep a cache of
              stat structures.
            * dnotify's interface to user-space is awful.  Signals?
    
    inotify provides a more usable, simple, powerful solution to file change
    notification:
    
            * inotify's interface is a system call that returns a fd, not SIGIO.
    	  You get a single fd, which is select()-able.
            * inotify has an event that says "the filesystem that the item
              you were watching is on was unmounted."
            * inotify can watch directories or files.
    
    Inotify is currently used by Beagle (a desktop search infrastructure),
    Gamin (a FAM replacement), and other projects.
    
    See Documentation/filesystems/inotify.txt.
    Signed-off-by: default avatarRobert Love <rml@novell.com>
    Cc: John McCutchan <ttb@tentacle.dhs.org>
    Cc: Christoph Hellwig <hch@lst.de>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    0eeca283
fsnotify.h 5.91 KB
#ifndef _LINUX_FS_NOTIFY_H
#define _LINUX_FS_NOTIFY_H

/*
 * include/linux/fsnotify.h - generic hooks for filesystem notification, to
 * reduce in-source duplication from both dnotify and inotify.
 *
 * We don't compile any of this away in some complicated menagerie of ifdefs.
 * Instead, we rely on the code inside to optimize away as needed.
 *
 * (C) Copyright 2005 Robert Love
 */

#ifdef __KERNEL__

#include <linux/dnotify.h>
#include <linux/inotify.h>

/*
 * fsnotify_move - file old_name at old_dir was moved to new_name at new_dir
 */
static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
				 const char *old_name, const char *new_name,
				 int isdir)
{
	u32 cookie = inotify_get_cookie();

	if (old_dir == new_dir)
		inode_dir_notify(old_dir, DN_RENAME);
	else {
		inode_dir_notify(old_dir, DN_DELETE);
		inode_dir_notify(new_dir, DN_CREATE);
	}

	if (isdir)
		isdir = IN_ISDIR;
	inotify_inode_queue_event(old_dir, IN_MOVED_FROM|isdir,cookie,old_name);
	inotify_inode_queue_event(new_dir, IN_MOVED_TO|isdir, cookie, new_name);
}

/*
 * fsnotify_unlink - file was unlinked
 */
static inline void fsnotify_unlink(struct dentry *dentry, struct inode *dir)
{
	struct inode *inode = dentry->d_inode;

	inode_dir_notify(dir, DN_DELETE);
	inotify_inode_queue_event(dir, IN_DELETE, 0, dentry->d_name.name);
	inotify_inode_queue_event(inode, IN_DELETE_SELF, 0, NULL);

	inotify_inode_is_dead(inode);
}

/*
 * fsnotify_rmdir - directory was removed
 */
static inline void fsnotify_rmdir(struct dentry *dentry, struct inode *inode,
				  struct inode *dir)
{
	inode_dir_notify(dir, DN_DELETE);
	inotify_inode_queue_event(dir,IN_DELETE|IN_ISDIR,0,dentry->d_name.name);
	inotify_inode_queue_event(inode, IN_DELETE_SELF | IN_ISDIR, 0, NULL);
	inotify_inode_is_dead(inode);
}

/*
 * fsnotify_create - 'name' was linked in
 */
static inline void fsnotify_create(struct inode *inode, const char *name)
{
	inode_dir_notify(inode, DN_CREATE);
	inotify_inode_queue_event(inode, IN_CREATE, 0, name);
}

/*
 * fsnotify_mkdir - directory 'name' was created
 */
static inline void fsnotify_mkdir(struct inode *inode, const char *name)
{
	inode_dir_notify(inode, DN_CREATE);
	inotify_inode_queue_event(inode, IN_CREATE | IN_ISDIR, 0, name);
}

/*
 * fsnotify_access - file was read
 */
static inline void fsnotify_access(struct dentry *dentry)
{
	struct inode *inode = dentry->d_inode;
	u32 mask = IN_ACCESS;

	if (S_ISDIR(inode->i_mode))
		mask |= IN_ISDIR;

	dnotify_parent(dentry, DN_ACCESS);
	inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
	inotify_inode_queue_event(inode, mask, 0, NULL);
}

/*
 * fsnotify_modify - file was modified
 */
static inline void fsnotify_modify(struct dentry *dentry)
{
	struct inode *inode = dentry->d_inode;
	u32 mask = IN_MODIFY;

	if (S_ISDIR(inode->i_mode))
		mask |= IN_ISDIR;

	dnotify_parent(dentry, DN_MODIFY);
	inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
	inotify_inode_queue_event(inode, mask, 0, NULL);
}

/*
 * fsnotify_open - file was opened
 */
static inline void fsnotify_open(struct dentry *dentry)
{
	struct inode *inode = dentry->d_inode;
	u32 mask = IN_OPEN;

	if (S_ISDIR(inode->i_mode))
		mask |= IN_ISDIR;

	inotify_inode_queue_event(inode, mask, 0, NULL);
	inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
}

/*
 * fsnotify_close - file was closed
 */
static inline void fsnotify_close(struct file *file)
{
	struct dentry *dentry = file->f_dentry;
	struct inode *inode = dentry->d_inode;
	const char *name = dentry->d_name.name;
	mode_t mode = file->f_mode;
	u32 mask = (mode & FMODE_WRITE) ? IN_CLOSE_WRITE : IN_CLOSE_NOWRITE;

	if (S_ISDIR(inode->i_mode))
		mask |= IN_ISDIR;

	inotify_dentry_parent_queue_event(dentry, mask, 0, name);
	inotify_inode_queue_event(inode, mask, 0, NULL);
}

/*
 * fsnotify_xattr - extended attributes were changed
 */
static inline void fsnotify_xattr(struct dentry *dentry)
{
	struct inode *inode = dentry->d_inode;
	u32 mask = IN_ATTRIB;

	if (S_ISDIR(inode->i_mode))
		mask |= IN_ISDIR;

	inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
	inotify_inode_queue_event(inode, mask, 0, NULL);
}

/*
 * fsnotify_change - notify_change event.  file was modified and/or metadata
 * was changed.
 */
static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
{
	struct inode *inode = dentry->d_inode;
	int dn_mask = 0;
	u32 in_mask = 0;

	if (ia_valid & ATTR_UID) {
		in_mask |= IN_ATTRIB;
		dn_mask |= DN_ATTRIB;
	}
	if (ia_valid & ATTR_GID) {
		in_mask |= IN_ATTRIB;
		dn_mask |= DN_ATTRIB;
	}
	if (ia_valid & ATTR_SIZE) {
		in_mask |= IN_MODIFY;
		dn_mask |= DN_MODIFY;
	}
	/* both times implies a utime(s) call */
	if ((ia_valid & (ATTR_ATIME | ATTR_MTIME)) == (ATTR_ATIME | ATTR_MTIME))
	{
		in_mask |= IN_ATTRIB;
		dn_mask |= DN_ATTRIB;
	} else if (ia_valid & ATTR_ATIME) {
		in_mask |= IN_ACCESS;
		dn_mask |= DN_ACCESS;
	} else if (ia_valid & ATTR_MTIME) {
		in_mask |= IN_MODIFY;
		dn_mask |= DN_MODIFY;
	}
	if (ia_valid & ATTR_MODE) {
		in_mask |= IN_ATTRIB;
		dn_mask |= DN_ATTRIB;
	}

	if (dn_mask)
		dnotify_parent(dentry, dn_mask);
	if (in_mask) {
		if (S_ISDIR(inode->i_mode))
			in_mask |= IN_ISDIR;
		inotify_inode_queue_event(inode, in_mask, 0, NULL);
		inotify_dentry_parent_queue_event(dentry, in_mask, 0,
						  dentry->d_name.name);
	}
}

#ifdef CONFIG_INOTIFY	/* inotify helpers */

/*
 * fsnotify_oldname_init - save off the old filename before we change it
 */
static inline const char *fsnotify_oldname_init(const char *name)
{
	return kstrdup(name, GFP_KERNEL);
}

/*
 * fsnotify_oldname_free - free the name we got from fsnotify_oldname_init
 */
static inline void fsnotify_oldname_free(const char *old_name)
{
	kfree(old_name);
}

#else	/* CONFIG_INOTIFY */

static inline const char *fsnotify_oldname_init(const char *name)
{
	return NULL;
}

static inline void fsnotify_oldname_free(const char *old_name)
{
}

#endif	/* ! CONFIG_INOTIFY */

#endif	/* __KERNEL__ */

#endif	/* _LINUX_FS_NOTIFY_H */