From: David Howells <dhowells@redhat.com>
To: viro@zeniv.linux.org.uk
Cc: dhowells@redhat.com, raven@themaw.net, mszeredi@redhat.com,
christian@brauner.io, linux-api@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 17/19] notifications: sample: Display superblock notifications [ver #16]
Date: Tue, 18 Feb 2020 17:07:07 +0000 [thread overview]
Message-ID: <158204562708.3299825.13250962106287188749.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <158204549488.3299825.3783690177353088425.stgit@warthog.procyon.org.uk>
The notification is run as:
./watch_test
and it then watches "/mnt" for superblock notifications:
# mount -t tmpfs none /mnt
# ./watch_test &
# mount -o remount,ro /mnt
# mount -o remount,rw /mnt
producing:
# ./watch_test
NOTIFY[000]: ty=000003 sy=00 i=03010010
SUPER 157eb57ca7 change=0[readonly]
read() = 16
NOTIFY[000]: ty=000002 sy=04 i=02010010
MOUNT 000001a0 change=4[setattr] aux=0
read() = 16
NOTIFY[000]: ty=000002 sy=04 i=02010010
MOUNT 000001a0 change=4[setattr] aux=0
Signed-off-by: David Howells <dhowells@redhat.com>
---
samples/watch_queue/watch_test.c | 39 +++++++++++++++++++++++++++++++++++++-
1 file changed, 38 insertions(+), 1 deletion(-)
diff --git a/samples/watch_queue/watch_test.c b/samples/watch_queue/watch_test.c
index 49d185150506..eea3bd8c6569 100644
--- a/samples/watch_queue/watch_test.c
+++ b/samples/watch_queue/watch_test.c
@@ -29,6 +29,9 @@
#ifndef __NR_watch_mount
#define __NR_watch_mount -1
#endif
+#ifndef __NR_watch_sb
+#define __NR_watch_sb -1
+#endif
#define BUF_SIZE 256
@@ -82,6 +85,24 @@ static void saw_mount_change(struct watch_notification *n, size_t len)
m->triggered_on, n->subtype, mount_subtypes[n->subtype], m->changed_mount);
}
+static const char *super_subtypes[256] = {
+ [NOTIFY_SUPERBLOCK_READONLY] = "readonly",
+ [NOTIFY_SUPERBLOCK_ERROR] = "error",
+ [NOTIFY_SUPERBLOCK_EDQUOT] = "edquot",
+ [NOTIFY_SUPERBLOCK_NETWORK] = "network",
+};
+
+static void saw_super_change(struct watch_notification *n, size_t len)
+{
+ struct superblock_notification *s = (struct superblock_notification *)n;
+
+ if (len < sizeof(struct superblock_notification))
+ return;
+
+ printf("SUPER %08llx change=%u[%s]\n",
+ s->sb_id, n->subtype, super_subtypes[n->subtype]);
+}
+
/*
* Consume and display events.
*/
@@ -161,6 +182,9 @@ static void consumer(int fd)
case WATCH_TYPE_MOUNT_NOTIFY:
saw_mount_change(&n.n, len);
break;
+ case WATCH_TYPE_SB_NOTIFY:
+ saw_super_change(&n.n, len);
+ break;
}
p += len;
@@ -169,7 +193,7 @@ static void consumer(int fd)
}
static struct watch_notification_filter filter = {
- .nr_filters = 2,
+ .nr_filters = 3,
.filters = {
[0] = {
.type = WATCH_TYPE_KEY_NOTIFY,
@@ -180,6 +204,14 @@ static struct watch_notification_filter filter = {
// Reject move-from notifications
.subtype_filter[0] = UINT_MAX & ~(1 << NOTIFY_MOUNT_MOVE_FROM),
},
+ [2] = {
+ .type = WATCH_TYPE_SB_NOTIFY,
+ // Only accept notification of changes to R/O state
+ .subtype_filter[0] = (1 << NOTIFY_SUPERBLOCK_READONLY),
+ // Only accept notifications of change-to-R/O
+ .info_mask = WATCH_INFO_FLAG_0,
+ .info_filter = WATCH_INFO_FLAG_0,
+ },
},
};
@@ -218,6 +250,11 @@ int main(int argc, char **argv)
exit(1);
}
+ if (syscall(__NR_watch_sb, AT_FDCWD, "/mnt", 0, fd, 0x03) == -1) {
+ perror("watch_sb");
+ exit(1);
+ }
+
consumer(fd);
exit(0);
}
next prev parent reply other threads:[~2020-02-18 17:07 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 17:04 [PATCH 00/19] VFS: Filesystem information and notifications [ver #16] David Howells
2020-02-18 17:05 ` [PATCH 01/19] vfs: syscall: Add fsinfo() to query filesystem information " David Howells
2020-02-19 16:31 ` Darrick J. Wong
2020-02-19 20:07 ` Jann Horn
2020-02-20 10:34 ` David Howells
2020-02-20 15:48 ` Darrick J. Wong
2020-02-20 11:03 ` David Howells
2020-02-20 14:54 ` Jann Horn
2020-02-20 15:31 ` Darrick J. Wong
2020-02-18 17:05 ` [PATCH 02/19] fsinfo: Add syscalls to other arches " David Howells
2020-02-21 14:51 ` Christian Brauner
2020-02-21 18:10 ` Geert Uytterhoeven
2020-02-18 17:05 ` [PATCH 03/19] fsinfo: Provide a bitmap of supported features " David Howells
2020-02-19 16:37 ` Darrick J. Wong
2020-02-20 12:22 ` David Howells
2020-02-18 17:05 ` [PATCH 04/19] vfs: Add mount change counter " David Howells
2020-02-21 14:48 ` Christian Brauner
2020-02-18 17:05 ` [PATCH 05/19] vfs: Introduce a non-repeating system-unique superblock ID " David Howells
2020-02-19 16:53 ` Darrick J. Wong
2020-02-20 12:45 ` David Howells
2020-02-18 17:05 ` [PATCH 06/19] vfs: Allow fsinfo() to look up a mount object by " David Howells
2020-02-21 15:09 ` Christian Brauner
2020-02-18 17:05 ` [PATCH 07/19] vfs: Allow mount information to be queried by fsinfo() " David Howells
2020-02-18 17:05 ` [PATCH 08/19] vfs: fsinfo sample: Mount listing program " David Howells
2020-02-18 17:06 ` [PATCH 09/19] fsinfo: Allow the mount topology propogation flags to be retrieved " David Howells
2020-02-18 17:06 ` [PATCH 10/19] fsinfo: Add API documentation " David Howells
2020-02-18 17:06 ` [PATCH 11/19] afs: Support fsinfo() " David Howells
2020-02-19 21:01 ` Jann Horn
2020-02-20 12:58 ` David Howells
2020-02-20 14:58 ` Jann Horn
2020-02-21 13:26 ` David Howells
2020-02-18 17:06 ` [PATCH 12/19] security: Add hooks to rule on setting a superblock or mount watch " David Howells
2020-02-18 17:06 ` [PATCH 13/19] vfs: Add a mount-notification facility " David Howells
2020-02-19 22:40 ` Jann Horn
2020-02-19 22:55 ` Jann Horn
2020-02-21 12:24 ` David Howells
2020-02-21 15:49 ` Jann Horn
2020-02-21 17:06 ` David Howells
2020-02-21 17:36 ` seq_lock and lockdep_is_held() assertions Jann Horn
2020-02-21 18:02 ` John Stultz
2020-02-18 17:06 ` [PATCH 14/19] notifications: sample: Display mount tree change notifications [ver #16] David Howells
2020-02-18 17:06 ` [PATCH 15/19] vfs: Add superblock " David Howells
2020-02-19 23:08 ` Jann Horn
2020-02-21 14:23 ` David Howells
2020-02-21 15:44 ` Jann Horn
2020-02-21 16:33 ` David Howells
2020-02-21 16:41 ` Jann Horn
2020-02-21 17:11 ` David Howells
2020-02-18 17:06 ` [PATCH 16/19] fsinfo: Provide superblock notification counter " David Howells
2020-02-18 17:07 ` David Howells [this message]
2020-02-18 17:07 ` [PATCH 18/19] ext4: Add example fsinfo information " David Howells
2020-02-19 17:04 ` Darrick J. Wong
2020-02-20 0:53 ` kbuild test robot
2020-02-21 14:43 ` David Howells
2020-02-21 16:26 ` Darrick J. Wong
2020-02-18 17:07 ` [PATCH 19/19] nfs: Add example filesystem " David Howells
2020-02-20 2:13 ` kbuild test robot
2020-02-20 2:20 ` kbuild test robot
2020-02-18 18:12 ` David Howells
2020-02-19 10:23 ` [PATCH 00/19] VFS: Filesystem information and notifications " Stefan Metzmacher
2020-02-19 14:46 ` Christian Brauner
2020-02-19 15:50 ` Darrick J. Wong
2020-02-20 4:42 ` Ian Kent
2020-02-20 9:09 ` Christian Brauner
2020-02-20 11:30 ` Ian Kent
2020-02-19 16:16 ` David Howells
2020-02-21 12:57 ` David Howells
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