Hi David, I was surprised to see this because I'm working on the very same problem. But since I didn't have a reproducer I've painstakingly worked through the map reload related code. I don't know if my changes have fixed the problem but I can post them for you to try them out. The main reason I would prefer to use my changes (if they do fix the problem) is that I found quite a few problems with the map reload not working properly which lead to spending a bunch of time on that. One of the changes fixes the valid entry lookup and removes setting the entry negative in lookup_prune_one_cache() and I think fixes the devid handling in do_readmap_mount(). I'm not quite finished the series yet so I'll post it when I have, hopefully today. Umm, I probably should give your reproducer a go ... perhaps later ... Ian On 1/8/25 23:22, David Disseldorp wrote:
This effectively reverts commit 21ce28d ("autofs-5.1.4 - mark removed cache entry negative"), which causes the kernel to stall in autofs_wait for the following workload: cat > /etc/auto.direct <<EOF echo "/nfs/share $mount_args ${NFS_SERVER}:/${NFS_SHARE}" EOF setsid --fork automount --debug --foreground &> /automount.log sleep 1 touch /test.run setsid --fork /bin/bash -c \ "while [[ -f /test.run ]]; do df -ia >> /test.log; sleep 1; done" echo "df loop logging to /test.log" sleep 2 echo "changing and reloading auto.direct" echo > /etc/auto.direct killall -HUP automount sleep 2 echo "unmounting..." umount /nfs/share || echo "umount failed" The current behaviour sees us hit: handle_packet_missing_direct:1352: can't find map entry for () ...which doesn't respond to the kernel, triggering the stall. This approach adds a new MOUNT_FLAG_STALE flag to track removed map entries. While keeping enough state around to respond for the handle_packet_missing_direct case. RFC: - needs further testing (e.g. indirect maps) - I'm not familiar with the codebase so this may be the wrong approach - we may need a background job to purge MOUNT_FLAG_STALE entries? Signed-off-by: David Disseldorp <ddiss@xxxxxxx> --- daemon/direct.c | 8 ++++++-- daemon/indirect.c | 8 ++++++-- daemon/lookup.c | 11 ++++------- include/automount.h | 3 +++ 4 files changed, 19 insertions(+), 11 deletions(-) diff --git a/daemon/direct.c b/daemon/direct.c index 42baac8..5e78c40 100644 --- a/daemon/direct.c +++ b/daemon/direct.c @@ -1389,8 +1389,12 @@ int handle_packet_missing_direct(struct autofs_point *ap, autofs_packet_missing_ return 0; }- /* Check if we recorded a mount fail for this key */- if (me->status >= monotonic_time(NULL)) { + /* + * Check if we recorded a mount fail for this key, or the entry has + * been removed. + */ + if (me->status >= monotonic_time(NULL) || + me->flags & MOUNT_FLAG_STALE) { ops->send_fail(ap->logopt, ioctlfd, pkt->wait_queue_token, -ENOENT); ops->close(ap->logopt, ioctlfd); diff --git a/daemon/indirect.c b/daemon/indirect.c index 7d4aad7..934bb74 100644 --- a/daemon/indirect.c +++ b/daemon/indirect.c @@ -798,8 +798,12 @@ int handle_packet_missing_indirect(struct autofs_point *ap, autofs_packet_missinme = lookup_source_mapent(ap, pkt->name, LKP_DISTINCT);if (me) { - /* Check if we recorded a mount fail for this key */ - if (me->status >= monotonic_time(NULL)) { + /* + * Check if we recorded a mount fail for this key, or the entry + * has been removed. + */ + if (me->status >= monotonic_time(NULL) || + me->flags & MOUNT_FLAG_STALE) { ops->send_fail(ap->logopt, ap->ioctlfd, pkt->wait_queue_token, -ENOENT); cache_unlock(me->mc); diff --git a/daemon/lookup.c b/daemon/lookup.c index dc77948..ad0b460 100644 --- a/daemon/lookup.c +++ b/daemon/lookup.c @@ -1416,15 +1416,12 @@ void lookup_prune_one_cache(struct autofs_point *ap, struct mapent_cache *mc, ti if (valid && valid->mc == mc) { /* * We've found a map entry that has been removed from - * the current cache so it isn't really valid. Set the - * mapent negative to prevent further mount requests + * the current cache so it isn't really valid. Flag the + * mapent stale to prevent further mount requests * using the cache entry. */ - debug(ap->logopt, "removed map entry detected, mark negative"); - if (valid->mapent) { - free(valid->mapent); - valid->mapent = NULL; - } + debug(ap->logopt, "removed map entry detected, mark stale"); + valid->flags |= MOUNT_FLAG_STALE; cache_unlock(valid->mc); valid = NULL; } diff --git a/include/automount.h b/include/automount.h index 9548db8..007d020 100644 --- a/include/automount.h +++ b/include/automount.h @@ -548,6 +548,9 @@ struct kernel_mod_version { /* Indicator for applications to ignore the mount entry */ #define MOUNT_FLAG_IGNORE 0x1000+/* map has been removed, but we can't clean up yet */+#define MOUNT_FLAG_STALE 0x2000 + struct autofs_point { pthread_t thid; char *path; /* Mount point name */
