0eeca28300
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: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
109 lines
3.3 KiB
C
109 lines
3.3 KiB
C
/*
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* Inode based directory notification for Linux
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*
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* Copyright (C) 2005 John McCutchan
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*/
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#ifndef _LINUX_INOTIFY_H
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#define _LINUX_INOTIFY_H
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#include <linux/types.h>
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/*
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* struct inotify_event - structure read from the inotify device for each event
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*
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* When you are watching a directory, you will receive the filename for events
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* such as IN_CREATE, IN_DELETE, IN_OPEN, IN_CLOSE, ..., relative to the wd.
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*/
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struct inotify_event {
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__s32 wd; /* watch descriptor */
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__u32 mask; /* watch mask */
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__u32 cookie; /* cookie to synchronize two events */
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__u32 len; /* length (including nulls) of name */
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char name[0]; /* stub for possible name */
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};
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/* the following are legal, implemented events that user-space can watch for */
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#define IN_ACCESS 0x00000001 /* File was accessed */
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#define IN_MODIFY 0x00000002 /* File was modified */
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#define IN_ATTRIB 0x00000004 /* Metadata changed */
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#define IN_CLOSE_WRITE 0x00000008 /* Writtable file was closed */
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#define IN_CLOSE_NOWRITE 0x00000010 /* Unwrittable file closed */
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#define IN_OPEN 0x00000020 /* File was opened */
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#define IN_MOVED_FROM 0x00000040 /* File was moved from X */
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#define IN_MOVED_TO 0x00000080 /* File was moved to Y */
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#define IN_CREATE 0x00000100 /* Subfile was created */
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#define IN_DELETE 0x00000200 /* Subfile was deleted */
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#define IN_DELETE_SELF 0x00000400 /* Self was deleted */
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/* the following are legal events. they are sent as needed to any watch */
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#define IN_UNMOUNT 0x00002000 /* Backing fs was unmounted */
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#define IN_Q_OVERFLOW 0x00004000 /* Event queued overflowed */
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#define IN_IGNORED 0x00008000 /* File was ignored */
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/* helper events */
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#define IN_CLOSE (IN_CLOSE_WRITE | IN_CLOSE_NOWRITE) /* close */
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#define IN_MOVE (IN_MOVED_FROM | IN_MOVED_TO) /* moves */
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/* special flags */
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#define IN_ISDIR 0x40000000 /* event occurred against dir */
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#define IN_ONESHOT 0x80000000 /* only send event once */
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/*
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* All of the events - we build the list by hand so that we can add flags in
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* the future and not break backward compatibility. Apps will get only the
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* events that they originally wanted. Be sure to add new events here!
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*/
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#define IN_ALL_EVENTS (IN_ACCESS | IN_MODIFY | IN_ATTRIB | IN_CLOSE_WRITE | \
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IN_CLOSE_NOWRITE | IN_OPEN | IN_MOVED_FROM | \
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IN_MOVED_TO | IN_DELETE | IN_CREATE | IN_DELETE_SELF)
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#ifdef __KERNEL__
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#include <linux/dcache.h>
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#include <linux/fs.h>
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#include <linux/config.h>
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#ifdef CONFIG_INOTIFY
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extern void inotify_inode_queue_event(struct inode *, __u32, __u32,
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const char *);
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extern void inotify_dentry_parent_queue_event(struct dentry *, __u32, __u32,
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const char *);
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extern void inotify_unmount_inodes(struct list_head *);
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extern void inotify_inode_is_dead(struct inode *);
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extern u32 inotify_get_cookie(void);
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#else
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static inline void inotify_inode_queue_event(struct inode *inode,
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__u32 mask, __u32 cookie,
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const char *filename)
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{
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}
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static inline void inotify_dentry_parent_queue_event(struct dentry *dentry,
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__u32 mask, __u32 cookie,
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const char *filename)
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{
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}
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static inline void inotify_unmount_inodes(struct list_head *list)
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{
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}
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static inline void inotify_inode_is_dead(struct inode *inode)
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{
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}
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static inline u32 inotify_get_cookie(void)
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{
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return 0;
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}
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#endif /* CONFIG_INOTIFY */
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#endif /* __KERNEL __ */
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#endif /* _LINUX_INOTIFY_H */
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