This needs to be linked with -lkeyutils. It is run like: ./watch_test and watches "/" for mount changes and the current session keyring for key changes: # keyctl add user a a @s 1035096409 # keyctl unlink 1035096409 @s # mount -t tmpfs none /mnt/nfsv3tcp/ # umount /mnt/nfsv3tcp producing: # ./watch_test ptrs h=4 t=2 m=20003 NOTIFY[00000004-00000002] ty=0003 sy=0002 i=01000010 KEY 2ffc2e5d change=2[linked] aux=1035096409 ptrs h=6 t=4 m=20003 NOTIFY[00000006-00000004] ty=0003 sy=0003 i=01000010 KEY 2ffc2e5d change=3[unlinked] aux=1035096409 ptrs h=8 t=6 m=20003 NOTIFY[00000008-00000006] ty=0001 sy=0000 i=02000010 MOUNT 00000013 change=0[new_mount] aux=168 ptrs h=a t=8 m=20003 NOTIFY[0000000a-00000008] ty=0001 sy=0001 i=02000010 MOUNT 00000013 change=1[unmount] aux=168 Other events may be produced, such as with a failing disk: ptrs h=5 t=2 m=6000004 NOTIFY[00000005-00000002] ty=0004 sy=0006 i=04000018 BLOCK 00800050 e=6[critical medium] s=5be8 This corresponds to: print_req_error: critical medium error, dev sdf, sector 23528 flags 0 in dmesg. Signed-off-by: David Howells <dhowells@xxxxxxxxxx> --- samples/watch_queue/watch_test.c | 76 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 76 insertions(+) diff --git a/samples/watch_queue/watch_test.c b/samples/watch_queue/watch_test.c index f792c13614f4..0018ecac188a 100644 --- a/samples/watch_queue/watch_test.c +++ b/samples/watch_queue/watch_test.c @@ -30,6 +30,12 @@ #ifndef __NR_watch_devices #define __NR_watch_devices -1 #endif +#ifndef __NR_watch_mount +#define __NR_watch_mount -1 +#endif +#ifndef __NR_watch_sb +#define __NR_watch_sb -1 +#endif #define BUF_SIZE 4 @@ -61,6 +67,47 @@ static void saw_key_change(struct watch_notification *n) k->key_id, n->subtype, key_subtypes[n->subtype], k->aux); } +static const char *mount_subtypes[256] = { + [NOTIFY_MOUNT_NEW_MOUNT] = "new_mount", + [NOTIFY_MOUNT_UNMOUNT] = "unmount", + [NOTIFY_MOUNT_EXPIRY] = "expiry", + [NOTIFY_MOUNT_READONLY] = "readonly", + [NOTIFY_MOUNT_SETATTR] = "setattr", + [NOTIFY_MOUNT_MOVE_FROM] = "move_from", + [NOTIFY_MOUNT_MOVE_TO] = "move_to", +}; + +static void saw_mount_change(struct watch_notification *n) +{ + struct mount_notification *m = (struct mount_notification *)n; + unsigned int len = (n->info & WATCH_INFO_LENGTH) >> WATCH_INFO_LENGTH__SHIFT; + + if (len != sizeof(struct mount_notification) / WATCH_LENGTH_GRANULARITY) + return; + + printf("MOUNT %08x change=%u[%s] aux=%u\n", + 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) +{ + struct superblock_notification *s = (struct superblock_notification *)n; + unsigned int len = (n->info & WATCH_INFO_LENGTH) >> WATCH_INFO_LENGTH__SHIFT; + + if (len < sizeof(struct superblock_notification) / WATCH_LENGTH_GRANULARITY) + return; + + printf("SUPER %08llx change=%u[%s]\n", + s->sb_id, n->subtype, super_subtypes[n->subtype]); +} + static const char *block_subtypes[256] = { [NOTIFY_BLOCK_ERROR_TIMEOUT] = "timeout", [NOTIFY_BLOCK_ERROR_NO_SPACE] = "critical space allocation", @@ -159,6 +206,12 @@ static int consumer(int fd, struct watch_queue_buffer *buf) case WATCH_TYPE_USB_NOTIFY: saw_usb_event(n); break; + case WATCH_TYPE_MOUNT_NOTIFY: + saw_mount_change(n); + break; + case WATCH_TYPE_SB_NOTIFY: + saw_super_change(n); + break; } tail += (n->info & WATCH_INFO_LENGTH) >> WATCH_INFO_LENGTH__SHIFT; @@ -186,6 +239,19 @@ static struct watch_notification_filter filter = { .type = WATCH_TYPE_USB_NOTIFY, .subtype_filter[0] = UINT_MAX, }, + [3] = { + .type = WATCH_TYPE_MOUNT_NOTIFY, + // Reject move-from notifications + .subtype_filter[0] = UINT_MAX & ~(1 << NOTIFY_MOUNT_MOVE_FROM), + }, + [4] = { + .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, + }, }, }; @@ -229,5 +295,15 @@ int main(int argc, char **argv) exit(1); } + if (syscall(__NR_watch_mount, AT_FDCWD, "/", 0, fd, 0x02) == -1) { + perror("watch_mount"); + exit(1); + } + + if (syscall(__NR_watch_sb, AT_FDCWD, "/mnt", 0, fd, 0x03) == -1) { + perror("watch_sb"); + exit(1); + } + return consumer(fd, buf); }