From: Hannes Reinecke hare@suse.de
stable inclusion from linux-4.19.171 commit 97c5846e04532a0651da7016b4d35862993ea56d
--------------------------------
commit 809b1e4945774c9ec5619a8f4e2189b7b3833c0c upstream.
This reverts commit 644bda6f3460 ("dm table: fall back to getting device using name_to_dev_t()")
dm_get_dev_t() is just used to convert an arbitrary 'path' string into a dev_t. It doesn't presume that the device is present; that check will be done later, as the only caller is dm_get_device(), which does a dm_get_table_device() later on, which will properly open the device.
So if the path string already _is_ in major:minor representation we can convert it directly, avoiding a recursion into the filesystem to lookup the block device.
This avoids a hang in multipath_message() when the filesystem is inaccessible.
Fixes: 644bda6f3460 ("dm table: fall back to getting device using name_to_dev_t()") Cc: stable@vger.kernel.org Signed-off-by: Hannes Reinecke hare@suse.de Signed-off-by: Martin Wilck mwilck@suse.com Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com Signed-off-by: Cheng Jian cj.chengjian@huawei.com --- drivers/md/dm-table.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 4ac9ac151fd3..418671ba057a 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -431,14 +431,23 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, { int r; dev_t dev; + unsigned int major, minor; + char dummy; struct dm_dev_internal *dd; struct dm_table *t = ti->table;
BUG_ON(!t);
- dev = dm_get_dev_t(path); - if (!dev) - return -ENODEV; + if (sscanf(path, "%u:%u%c", &major, &minor, &dummy) == 2) { + /* Extract the major/minor numbers */ + dev = MKDEV(major, minor); + if (MAJOR(dev) != major || MINOR(dev) != minor) + return -EOVERFLOW; + } else { + dev = dm_get_dev_t(path); + if (!dev) + return -ENODEV; + }
dd = find_device(&t->devices, dev); if (!dd) {