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, jannh@google.com, darrick.wong@oracle.com,
linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 06/17] watch_queue: sample: Display superblock notifications [ver #17]
Date: Fri, 21 Feb 2020 18:02:36 +0000 [thread overview]
Message-ID: <158230815634.2185128.9507318728078606539.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <158230810644.2185128.16726948836367716086.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:[~2020-02-21 18:02 UTC|newest]
Thread overview: 117+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-21 18:01 [PATCH 00/17] VFS: Filesystem information and notifications [ver #17] David Howells
2020-02-21 18:01 ` [PATCH 01/17] watch_queue: Add security hooks to rule on setting mount and sb watches " David Howells
2020-02-21 18:02 ` [PATCH 02/17] watch_queue: Implement mount topology and attribute change notifications " David Howells
2020-02-21 18:02 ` [PATCH 03/17] watch_queue: sample: Display mount tree " David Howells
2020-02-21 18:02 ` [PATCH 04/17] watch_queue: Introduce a non-repeating system-unique superblock ID " David Howells
2020-02-21 18:02 ` [PATCH 05/17] watch_queue: Add superblock notifications " David Howells
2020-02-21 18:02 ` David Howells [this message]
2020-02-21 18:02 ` [PATCH 07/17] fsinfo: Add fsinfo() syscall to query filesystem information " David Howells
2020-02-26 2:29 ` Aleksa Sarai
2020-02-28 14:44 ` David Howells
2020-02-21 18:02 ` [PATCH 08/17] fsinfo: Provide a bitmap of supported features " David Howells
2020-02-21 18:03 ` [PATCH 09/17] fsinfo: Allow fsinfo() to look up a mount object by ID " David Howells
2020-02-21 18:03 ` [PATCH 10/17] fsinfo: Allow mount information to be queried " David Howells
2020-03-04 14:58 ` Miklos Szeredi
2020-03-04 16:10 ` Miklos Szeredi
2020-02-21 18:03 ` [PATCH 11/17] fsinfo: sample: Mount listing program " David Howells
2020-02-21 18:03 ` [PATCH 12/17] fsinfo: Allow the mount topology propogation flags to be retrieved " David Howells
2020-02-21 18:03 ` [PATCH 13/17] fsinfo: Query superblock unique ID and notification counter " David Howells
2020-02-21 18:03 ` [PATCH 14/17] fsinfo: Add API documentation " David Howells
2020-02-21 18:03 ` [PATCH 15/17] fsinfo: Add support for AFS " David Howells
2020-02-21 18:03 ` [PATCH 16/17] fsinfo: Add example support for Ext4 " David Howells
2020-02-21 18:04 ` [PATCH 17/17] fsinfo: Add example support for NFS " David Howells
2020-02-21 20:21 ` [PATCH 00/17] VFS: Filesystem information and notifications " James Bottomley
2020-02-24 10:24 ` Miklos Szeredi
2020-02-24 14:55 ` James Bottomley
2020-02-24 15:28 ` Miklos Szeredi
2020-02-25 12:13 ` Steven Whitehouse
2020-02-25 15:28 ` James Bottomley
2020-02-25 15:47 ` Steven Whitehouse
2020-02-26 9:11 ` Miklos Szeredi
2020-02-26 10:51 ` Steven Whitehouse
2020-02-27 5:06 ` Ian Kent
2020-02-27 9:36 ` Miklos Szeredi
2020-02-27 11:34 ` Ian Kent
2020-02-27 13:45 ` Miklos Szeredi
2020-02-27 15:14 ` Karel Zak
2020-02-28 0:43 ` Ian Kent
2020-02-28 8:35 ` Miklos Szeredi
2020-02-28 12:27 ` Greg Kroah-Hartman
2020-02-28 16:24 ` Miklos Szeredi
2020-02-28 17:15 ` Al Viro
2020-03-02 8:43 ` Miklos Szeredi
2020-03-02 10:34 ` Karel Zak
2020-02-28 16:42 ` David Howells
2020-02-28 15:08 ` James Bottomley
2020-02-28 15:40 ` Miklos Szeredi
2020-02-28 0:12 ` Ian Kent
2020-02-28 15:52 ` Christian Brauner
2020-02-28 16:36 ` David Howells
2020-03-02 9:09 ` Miklos Szeredi
2020-03-02 9:38 ` Greg Kroah-Hartman
2020-03-03 5:27 ` Ian Kent
2020-03-03 7:46 ` Miklos Szeredi
2020-03-06 16:25 ` Miklos Szeredi
2020-03-06 19:43 ` Al Viro
2020-03-06 19:54 ` Miklos Szeredi
2020-03-06 19:58 ` Al Viro
2020-03-06 20:05 ` Al Viro
2020-03-06 20:11 ` Miklos Szeredi
2020-03-06 20:37 ` Al Viro
2020-03-06 20:38 ` Al Viro
2020-03-06 20:45 ` Al Viro
2020-03-06 20:49 ` Al Viro
2020-03-06 20:51 ` Miklos Szeredi
2020-03-06 21:28 ` Al Viro
2020-03-06 20:56 ` Al Viro
2020-03-06 20:51 ` Miklos Szeredi
2020-03-07 9:48 ` Greg Kroah-Hartman
2020-03-07 20:48 ` Miklos Szeredi
2020-03-03 9:12 ` David Howells
2020-03-03 9:26 ` Miklos Szeredi
2020-03-03 9:48 ` Miklos Szeredi
2020-03-03 10:21 ` Steven Whitehouse
2020-03-03 10:32 ` Miklos Szeredi
2020-03-03 11:09 ` Ian Kent
2020-03-03 10:00 ` Christian Brauner
2020-03-03 10:13 ` Miklos Szeredi
2020-03-03 10:25 ` Christian Brauner
2020-03-03 11:33 ` Miklos Szeredi
2020-03-03 11:56 ` Christian Brauner
2020-03-03 11:38 ` Karel Zak
2020-03-03 13:03 ` Greg Kroah-Hartman
2020-03-03 13:14 ` Greg Kroah-Hartman
2020-03-03 13:34 ` Miklos Szeredi
2020-03-03 13:43 ` Greg Kroah-Hartman
2020-03-03 14:10 ` Greg Kroah-Hartman
2020-03-03 14:13 ` Jann Horn
2020-03-03 14:24 ` Greg Kroah-Hartman
2020-03-03 15:44 ` Jens Axboe
2020-03-03 16:37 ` Greg Kroah-Hartman
2020-03-03 16:51 ` Jeff Layton
2020-03-03 16:55 ` Jens Axboe
2020-03-03 19:02 ` Jeff Layton
2020-03-03 19:07 ` Jens Axboe
2020-03-03 19:23 ` Jens Axboe
2020-03-03 19:43 ` Jeff Layton
2020-03-03 20:33 ` Jens Axboe
2020-03-03 21:03 ` Jeff Layton
2020-03-03 21:20 ` Jens Axboe
2020-03-03 14:10 ` Miklos Szeredi
2020-03-03 14:29 ` Greg Kroah-Hartman
2020-03-03 14:40 ` Jann Horn
2020-03-03 16:51 ` Greg Kroah-Hartman
2020-03-03 16:57 ` Jann Horn
2020-03-03 20:15 ` Greg Kroah-Hartman
2020-03-03 14:40 ` David Howells
2020-03-04 4:20 ` Ian Kent
2020-03-03 14:19 ` David Howells
2020-03-03 16:59 ` Greg Kroah-Hartman
2020-03-03 14:23 ` Christian Brauner
2020-03-03 15:23 ` Greg Kroah-Hartman
2020-03-03 15:53 ` David Howells
2020-03-04 2:01 ` Ian Kent
2020-03-04 15:22 ` Karel Zak
2020-03-04 16:49 ` Greg Kroah-Hartman
2020-03-04 17:55 ` Karel Zak
2020-03-03 14:09 ` David Howells
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