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[PATCH] inotify: fix event loss on hardlinked files

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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: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
John McCutchan 2005-09-06 15:18:02 -07:00 committed by Linus Torvalds
parent 8191151d09
commit 7ea6040b0e
2 changed files with 9 additions and 1 deletions
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9
fs/inotify.c
View File

@ -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)) {
@ -966,7 +970,10 @@ asmlinkage long sys_inotify_add_watch(int fd, const char __user *path, u32 mask)
*/
old = inode_find_dev(inode, dev);
if (unlikely(old)) {
old->mask = mask;
if (mask_add)
old->mask |= mask;
else
old->mask = mask;
ret = old->wd;
goto out;
}

1
include/linux/inotify.h
View File

@ -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 */