From 7533afa1d27ba1234146d31d2402c195cf195962 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Tue, 7 Feb 2023 08:33:06 -0500 Subject: [PATCH] dm: send just one event on resize, not two Device mapper sends an uevent when the device is suspended, using the function set_capacity_and_notify. However, this causes a race condition with udev. Udev skips scanning dm devices that are suspended. If we send an uevent while we are suspended, udev will be racing with device mapper resume code. If the device mapper resume code wins the race, udev will process the uevent after the device is resumed and it will properly scan the device. However, if udev wins the race, it will receive the uevent, find out that the dm device is suspended and skip scanning the device. This causes bugs such as systemd unmounting the device - see https://bugzilla.redhat.com/show_bug.cgi?id=2158628 This commit fixes this race. We replace the function set_capacity_and_notify with set_capacity, so that the uevent is not sent at this point. In do_resume, we detect if the capacity has changed and we pass a boolean variable need_resize_uevent to dm_kobject_uevent. dm_kobject_uevent adds "RESIZE=1" to the uevent if need_resize_uevent is set. Signed-off-by: Mikulas Patocka Tested-by: Peter Rajnoha Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer --- drivers/md/dm-ioctl.c | 13 ++++++++++--- drivers/md/dm.c | 27 +++++++++++++-------------- drivers/md/dm.h | 2 +- 3 files changed, 24 insertions(+), 18 deletions(-) diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index 9160159ef8816..a3b86716f606d 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -482,7 +482,7 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param, dm_table_event(table); dm_put_live_table(hc->md, srcu_idx); - if (!dm_kobject_uevent(hc->md, KOBJ_CHANGE, param->event_nr)) + if (!dm_kobject_uevent(hc->md, KOBJ_CHANGE, param->event_nr, false)) param->flags |= DM_UEVENT_GENERATED_FLAG; md = hc->md; @@ -995,7 +995,7 @@ static int dev_remove(struct file *filp, struct dm_ioctl *param, size_t param_si dm_ima_measure_on_device_remove(md, false); - if (!dm_kobject_uevent(md, KOBJ_REMOVE, param->event_nr)) + if (!dm_kobject_uevent(md, KOBJ_REMOVE, param->event_nr, false)) param->flags |= DM_UEVENT_GENERATED_FLAG; dm_put(md); @@ -1128,6 +1128,7 @@ static int do_resume(struct dm_ioctl *param) struct hash_cell *hc; struct mapped_device *md; struct dm_table *new_map, *old_map = NULL; + bool need_resize_uevent = false; down_write(&_hash_lock); @@ -1148,6 +1149,8 @@ static int do_resume(struct dm_ioctl *param) /* Do we need to load a new map ? */ if (new_map) { + sector_t old_size, new_size; + /* Suspend if it isn't already suspended */ if (param->flags & DM_SKIP_LOCKFS_FLAG) suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG; @@ -1156,6 +1159,7 @@ static int do_resume(struct dm_ioctl *param) if (!dm_suspended_md(md)) dm_suspend(md, suspend_flags); + old_size = dm_get_size(md); old_map = dm_swap_table(md, new_map); if (IS_ERR(old_map)) { dm_sync_table(md); @@ -1163,6 +1167,9 @@ static int do_resume(struct dm_ioctl *param) dm_put(md); return PTR_ERR(old_map); } + new_size = dm_get_size(md); + if (old_size && new_size && old_size != new_size) + need_resize_uevent = true; if (dm_table_get_mode(new_map) & FMODE_WRITE) set_disk_ro(dm_disk(md), 0); @@ -1175,7 +1182,7 @@ static int do_resume(struct dm_ioctl *param) if (!r) { dm_ima_measure_on_device_resume(md, new_map ? true : false); - if (!dm_kobject_uevent(md, KOBJ_CHANGE, param->event_nr)) + if (!dm_kobject_uevent(md, KOBJ_CHANGE, param->event_nr, need_resize_uevent)) param->flags |= DM_UEVENT_GENERATED_FLAG; } } diff --git a/drivers/md/dm.c b/drivers/md/dm.c index b424a6ee27baf..c391a618fb711 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2172,10 +2172,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t, if (size != dm_get_size(md)) memset(&md->geometry, 0, sizeof(md->geometry)); - if (!get_capacity(md->disk)) - set_capacity(md->disk, size); - else - set_capacity_and_notify(md->disk, size); + set_capacity(md->disk, size); dm_table_event_callback(t, event_callback, md); @@ -2968,23 +2965,25 @@ EXPORT_SYMBOL_GPL(dm_internal_resume_fast); * Event notification. *---------------------------------------------------------------*/ int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action, - unsigned cookie) + unsigned cookie, bool need_resize_uevent) { int r; unsigned noio_flag; char udev_cookie[DM_COOKIE_LENGTH]; - char *envp[] = { udev_cookie, NULL }; - - noio_flag = memalloc_noio_save(); - - if (!cookie) - r = kobject_uevent(&disk_to_dev(md->disk)->kobj, action); - else { + char *envp[3] = { NULL, NULL, NULL }; + char **envpp = envp; + if (cookie) { snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u", DM_COOKIE_ENV_VAR_NAME, cookie); - r = kobject_uevent_env(&disk_to_dev(md->disk)->kobj, - action, envp); + *envpp++ = udev_cookie; } + if (need_resize_uevent) { + *envpp++ = "RESIZE=1"; + } + + noio_flag = memalloc_noio_save(); + + r = kobject_uevent_env(&disk_to_dev(md->disk)->kobj, action, envp); memalloc_noio_restore(noio_flag); diff --git a/drivers/md/dm.h b/drivers/md/dm.h index 5201df03ce402..a9a3ffcad084c 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -203,7 +203,7 @@ int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode, void dm_put_table_device(struct mapped_device *md, struct dm_dev *d); int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action, - unsigned cookie); + unsigned cookie, bool need_resize_uevent); void dm_internal_suspend(struct mapped_device *md); void dm_internal_resume(struct mapped_device *md); -- 2.39.2