[PATCH 1/3] fsnotify: use def_bool in kconfig instead of letting the user choose

[PATCH 1/3] fsnotify: use def_bool in kconfig instead of letting the user choose

[Eric Paris]

fsnotify doens't give the user anything.  If someone chooses inotify or
dnotify it should build fsnotify, if they don't select one it shouldn't be
built.  This patch changes fsnotify to be a def_bool=n and makes everything
else select it.  Also fixes the issue people complained about on lwn where
gdm hung because they didn't have inotify and they didn't get the inotify
build option.....

Signed-off-by: Eric Paris <eparis@redhat.com>
---

 fs/notify/Kconfig         |   12 +-----------
 fs/notify/dnotify/Kconfig |    2 +-
 fs/notify/inotify/Kconfig |    2 +-
 3 files changed, 3 insertions(+), 13 deletions(-)

diff --git a/fs/notify/Kconfig b/fs/notify/Kconfig
index 31dac7e..dffbb09 100644
--- a/fs/notify/Kconfig
+++ b/fs/notify/Kconfig
@@ -1,15 +1,5 @@
 config FSNOTIFY
-	bool "Filesystem notification backend"
-	default y
-	---help---
-	   fsnotify is a backend for filesystem notification.  fsnotify does
-	   not provide any userspace interface but does provide the basis
-	   needed for other notification schemes such as dnotify, inotify,
-	   and fanotify.
-
-	   Say Y here to enable fsnotify suport.
-
-	   If unsure, say Y.
+	def_bool n
 
 source "fs/notify/dnotify/Kconfig"
 source "fs/notify/inotify/Kconfig"
diff --git a/fs/notify/dnotify/Kconfig b/fs/notify/dnotify/Kconfig
index 904ff8d..f9c1ca1 100644
--- a/fs/notify/dnotify/Kconfig
+++ b/fs/notify/dnotify/Kconfig
@@ -1,6 +1,6 @@
 config DNOTIFY
 	bool "Dnotify support"
-	depends on FSNOTIFY
+	select FSNOTIFY
 	default y
 	help
 	  Dnotify is a directory-based per-fd file change notification system
diff --git a/fs/notify/inotify/Kconfig b/fs/notify/inotify/Kconfig
index 5356884..3e56dbf 100644
--- a/fs/notify/inotify/Kconfig
+++ b/fs/notify/inotify/Kconfig
@@ -15,7 +15,7 @@ config INOTIFY
 
 config INOTIFY_USER
 	bool "Inotify support for userspace"
-	depends on FSNOTIFY
+	select FSNOTIFY
 	default y
 	---help---
 	  Say Y here to enable inotify support for userspace, including the

[PATCH 2/3] inotify: check filename before dropping repeat events

[Eric Paris]

inotify drops events if the last event on the queue is the same as the
current event.  But it does 2 things wrong.  First it is comparing old->inode
with new->inode.  But after an event if put on the queue the ->inode is no
longer allowed to be used.  It's possible between the last event and this new
event the inode could be reused and we would falsely match the inode's memory
address between two differing events.

The second problem is that when a file is removed fsnotify is passed the
negative dentry for the removed object rather than the postive dentry from
immediately before the removal.  This mean the (broken) inotify tail drop code
was matching the NULL ->inode of differing events.

The fix is to check the file name which is stored with events when doing the
tail drop instead of wrongly checking the address of the stored ->inode.

Reported-by: Scott James Remnant <scott@ubuntu.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
---

 fs/notify/notification.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/notify/notification.c b/fs/notify/notification.c
index 959b73e..d1fbbea 100644
--- a/fs/notify/notification.c
+++ b/fs/notify/notification.c
@@ -136,10 +136,14 @@ static bool event_compare(struct fsnotify_event *old, struct fsnotify_event *new
 {
 	if ((old->mask == new->mask) &&
 	    (old->to_tell == new->to_tell) &&
-	    (old->data_type == new->data_type)) {
+	    (old->data_type == new->data_type) &&
+	    (old->name_len == new->name_len)) {
 		switch (old->data_type) {
 		case (FSNOTIFY_EVENT_INODE):
-			if (old->inode == new->inode)
+			/* remember, after old was put on the wait_q we aren't
+			 * allowed to look at the inode any more, only thing
+			 * left to check was if the file_name is the same */
+			if (old->name_len && !strcmp(old->file_name, new->file_name))
 				return true;
 			break;
 		case (FSNOTIFY_EVENT_PATH):

[PATCH 3/3] fsnotify: fix inotify tail drop check with path entries

[Eric Paris]

fsnotify drops new events when they are the same as the tail event on the
queue to be sent to userspace.  The problem is that if the event comes with
a path we forget to break out of the switch statement and fall into the
code path which matches on events that do not have any type of file backed
information (things like IN_UNMOUNT and IN_Q_OVERFLOW).  The problem is
that this code thinks all such events should be dropped.  Fix is to add a
break.

Signed-off-by: Eric Paris <eparis@redhat.com>
---

 fs/notify/notification.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/fs/notify/notification.c b/fs/notify/notification.c
index d1fbbea..99d840b 100644
--- a/fs/notify/notification.c
+++ b/fs/notify/notification.c
@@ -150,6 +150,7 @@ static bool event_compare(struct fsnotify_event *old, struct fsnotify_event *new
 			if ((old->path.mnt == new->path.mnt) &&
 			    (old->path.dentry == new->path.dentry))
 				return true;
+			break;
 		case (FSNOTIFY_EVENT_NONE):
 			return true;
 		};