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Commit 7ea6040b authored by John McCutchan's avatar John McCutchan Committed by Linus Torvalds
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[PATCH] inotify: fix event loss on hardlinked files 



People have run into a problem when they do this:

watch (file1, all_events);
watch (file2, some_events);

if file2 is a hard link to file1, some events will be missed because by
default we replace the mask.  The patch below adds a flag IN_MASK_ADD which
will cause inotify to add to the existing mask if present.

Signed-off-by: default avatarJohn McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: default avatarRobert Love <rml@novell.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 8191151d

fs/inotify.c

+8 −1
Original line number Diff line number Diff line
@@ -931,6 +931,7 @@ asmlinkage long sys_inotify_add_watch(int fd, const char __user *path, u32 mask) 
	struct nameidata nd;

	struct file *filp;

	int ret, fput_needed;

	int mask_add = 0;



	filp = fget_light(fd, &fput_needed);

	if (unlikely(!filp))
@@ -953,6 +954,9 @@ asmlinkage long sys_inotify_add_watch(int fd, const char __user *path, u32 mask) 
	down(&inode->inotify_sem);

	down(&dev->sem);



	if (mask & IN_MASK_ADD)

		mask_add = 1;



	/* don't let user-space set invalid bits: we don't want flags set */

	mask &= IN_ALL_EVENTS;

	if (unlikely(!mask)) {
@@ -966,6 +970,9 @@ asmlinkage long sys_inotify_add_watch(int fd, const char __user *path, u32 mask) 
	 */

	old = inode_find_dev(inode, dev);

	if (unlikely(old)) {

		if (mask_add)

			old->mask |= mask;

		else

			old->mask = mask;

		ret = old->wd;

		goto out;

include/linux/inotify.h

+1 −0
Original line number Diff line number Diff line
@@ -47,6 +47,7 @@ struct inotify_event { 
#define IN_MOVE			(IN_MOVED_FROM | IN_MOVED_TO) /* moves */



/* special flags */

#define IN_MASK_ADD		0x20000000	/* add to the mask of an already existing watch */

#define IN_ISDIR		0x40000000	/* event occurred against dir */

#define IN_ONESHOT		0x80000000	/* only send event once */