From: Tang Junhui <tang.junhui@xxxxxxxxxx> Hello Ryan Harper > From: Ryan Harper <ryan.harper@xxxxxxxxxxxxx> > > BugLink: http://bugs.launchpad.net/bugs/1729145 > > A bug is preventing /dev/bcache/by-uuid links from being created after reboot. > It appears that since the initramfs loads the bcache module which probes and > finds all of the cache devices and backing devices I am just curious, is initramfs or the loaded bcache module probes and finds all of the cache devices and backing devices? As far as I known, bcache never does this thing, and all the bcache devices were registered by uevent message through udev rules. > then once the rootfs is > mounted and udev gets to run, the bcache kernel module does not emit the > CACHED_UUID value into the environment if the underlying devices are already registered. > > With this patch, instead of just failing with "device already registered" > the kernel emits another uevent with CACHED_UUID which would be processed > another time to set up a symlink. > > > - decouple emitting a cached_dev CHANGE uevent which includes dev.uuid > and dev.label from bch_cached_dev_run() which only happens when a > bcacheX device is bound to the actual backing block device (bcache0 -> vdb) > > - update bch_cached_dev_run() to invoke bch_cached_dev_emit_change() as > needed; no functional code path changes here > > - Modify register_bcache to detect a re-registering of a bcache > cached_dev, and in that case call bcache_cached_dev_emit_change() to > > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Ryan Harper <ryan.harper@xxxxxxxxxxxxx> > Signed-off-by: Joseph Salisbury <joseph.salisbury@xxxxxxxxxxxxx> > --- > drivers/md/bcache/bcache.h | 1 + > drivers/md/bcache/super.c | 53 +++++++++++++++++++++++++++++++++++++--------- > 2 files changed, 44 insertions(+), 10 deletions(-) > > diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h > index 02619ca..8ed7e7a 100644 > --- a/drivers/md/bcache/bcache.h > +++ b/drivers/md/bcache/bcache.h > @@ -906,6 +906,7 @@ int bch_flash_dev_create(struct cache_set *c, uint64_t size); > > int bch_cached_dev_attach(struct cached_dev *, struct cache_set *); > void bch_cached_dev_detach(struct cached_dev *); > +void bch_cached_dev_emit_change(struct cached_dev *); > void bch_cached_dev_run(struct cached_dev *); > void bcache_device_stop(struct bcache_device *); > > diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c > index 04608da..9ff0aac 100644 > --- a/drivers/md/bcache/super.c > +++ b/drivers/md/bcache/super.c > @@ -834,7 +834,7 @@ static void calc_cached_dev_sectors(struct cache_set *c) > c->cached_dev_sectors = sectors; > } > > -void bch_cached_dev_run(struct cached_dev *dc) > +void bch_cached_dev_emit_change(struct cached_dev *dc) > { > struct bcache_device *d = &dc->disk; > char buf[SB_LABEL_SIZE + 1]; > @@ -849,9 +849,18 @@ void bch_cached_dev_run(struct cached_dev *dc) > buf[SB_LABEL_SIZE] = '\0'; > env[2] = kasprintf(GFP_KERNEL, "CACHED_LABEL=%s", buf); > > + /* won't show up in the uevent file, use udevadm monitor -e instead > + * only class / kset properties are persistent */ > + kobject_uevent_env(&disk_to_dev(d->disk)->kobj, KOBJ_CHANGE, env); > + kfree(env[1]); > + kfree(env[2]); > + > +} > + > +void bch_cached_dev_run(struct cached_dev *dc) > +{ > + struct bcache_device *d = &dc->disk; > if (atomic_xchg(&dc->running, 1)) { > - kfree(env[1]); > - kfree(env[2]); > return; > } > > @@ -867,11 +876,9 @@ void bch_cached_dev_run(struct cached_dev *dc) > > add_disk(d->disk); > bd_link_disk_holder(dc->bdev, dc->disk.disk); > - /* won't show up in the uevent file, use udevadm monitor -e instead > - * only class / kset properties are persistent */ > - kobject_uevent_env(&disk_to_dev(d->disk)->kobj, KOBJ_CHANGE, env); > - kfree(env[1]); > - kfree(env[2]); > + > + /* emit change event */ > + bch_cached_dev_emit_change(dc); > > if (sysfs_create_link(&d->kobj, &disk_to_dev(d->disk)->kobj, "dev") || > sysfs_create_link(&disk_to_dev(d->disk)->kobj, &d->kobj, "bcache")) > @@ -1916,6 +1923,21 @@ static bool bch_is_open_backing(struct block_device *bdev) { > return false; > } > > +static struct cached_dev *bch_find_cached_dev(struct block_device *bdev) { > + struct cache_set *c, *tc; > + struct cached_dev *dc, *t; > + > + list_for_each_entry_safe(c, tc, &bch_cache_sets, list) > + list_for_each_entry_safe(dc, t, &c->cached_devs, list) > + if (dc->bdev == bdev) > + return dc; > + list_for_each_entry_safe(dc, t, &uncached_devices, list) > + if (dc->bdev == bdev) > + return dc; > + > + return NULL; > +} > + > static bool bch_is_open_cache(struct block_device *bdev) { > struct cache_set *c, *tc; > struct cache *ca; > @@ -1941,6 +1963,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr, > struct cache_sb *sb = NULL; > struct block_device *bdev = NULL; > struct page *sb_page = NULL; > + struct cached_dev *dc = NULL; > > if (!try_module_get(THIS_MODULE)) > return -EBUSY; > @@ -1957,10 +1980,20 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr, > if (bdev == ERR_PTR(-EBUSY)) { > bdev = lookup_bdev(strim(path), 0); > mutex_lock(&bch_register_lock); > - if (!IS_ERR(bdev) && bch_is_open(bdev)) > + if (!IS_ERR(bdev) && bch_is_open(bdev)) { > err = "device already registered"; > - else > + /* emit CHANGE event for backing devices to export > + * CACHED_{UUID/LABEL} values to udev */ > + if (bch_is_open_backing(bdev)) { > + dc = bch_find_cached_dev(bdev); > + if (dc) { > + bch_cached_dev_emit_change(dc); > + err = "device already registered (emitting change event)"; > + } > + } > + } else { > err = "device busy"; > + } > mutex_unlock(&bch_register_lock); > if (!IS_ERR(bdev)) > bdput(bdev); > -- > 2.7.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-bcache" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html Thanks Tang Junhui -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
