From: Christoph Hellwig hch@lst.de
commit b9684a71fca793213378dd410cd11675d973eaa1 upstream.
Historically we did distinguish between a flag that surpressed partition scanning, and a combinations of the minors variable and another flag if any partitions were supported. This was generally confusing and doesn't make much sense, but some corner case uses of the loop driver actually do want to support manually added partitions on a device that does not actively scan for partitions. To make things worsee the loop driver also wants to dynamically toggle the scanning for partitions on a live gendisk, which makes the disk->flags updates non-atomic.
Introduce a new GD_SUPPRESS_PART_SCAN bit in disk->state that disables just scanning for partitions, and toggle that instead of GENHD_FL_NO_PART in the loop driver.
Fixes: 1ebe2e5f9d68 ("block: remove GENHD_FL_EXT_DEVT") Reported-by: Ming Lei ming.lei@redhat.com Signed-off-by: Christoph Hellwig hch@lst.de Reviewed-by: Ming Lei ming.lei@redhat.com Link: https://lore.kernel.org/r/20220527055806.1972352-1-hch@lst.de Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- block/genhd.c | 2 ++ drivers/block/loop.c | 8 ++++---- include/linux/genhd.h | 1 + 3 files changed, 7 insertions(+), 4 deletions(-)
--- a/block/genhd.c +++ b/block/genhd.c @@ -380,6 +380,8 @@ int disk_scan_partitions(struct gendisk
if (disk->flags & (GENHD_FL_NO_PART | GENHD_FL_HIDDEN)) return -EINVAL; + if (test_bit(GD_SUPPRESS_PART_SCAN, &disk->state)) + return -EINVAL; if (disk->open_partitions) return -EBUSY;
--- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1067,7 +1067,7 @@ static int loop_configure(struct loop_de lo->lo_flags |= LO_FLAGS_PARTSCAN; partscan = lo->lo_flags & LO_FLAGS_PARTSCAN; if (partscan) - lo->lo_disk->flags &= ~GENHD_FL_NO_PART; + clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
loop_global_unlock(lo, is_loop); if (partscan) @@ -1186,7 +1186,7 @@ static void __loop_clr_fd(struct loop_de */ lo->lo_flags = 0; if (!part_shift) - lo->lo_disk->flags |= GENHD_FL_NO_PART; + set_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state); mutex_lock(&lo->lo_mutex); lo->lo_state = Lo_unbound; mutex_unlock(&lo->lo_mutex); @@ -1296,7 +1296,7 @@ out_unfreeze:
if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) && !(prev_lo_flags & LO_FLAGS_PARTSCAN)) { - lo->lo_disk->flags &= ~GENHD_FL_NO_PART; + clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state); partscan = true; } out_unlock: @@ -2028,7 +2028,7 @@ static int loop_add(int i) * userspace tools. Parameters like this in general should be avoided. */ if (!part_shift) - disk->flags |= GENHD_FL_NO_PART; + set_bit(GD_SUPPRESS_PART_SCAN, &disk->state); atomic_set(&lo->lo_refcnt, 0); mutex_init(&lo->lo_mutex); lo->lo_number = i; --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -110,6 +110,7 @@ struct gendisk { #define GD_READ_ONLY 1 #define GD_DEAD 2 #define GD_NATIVE_CAPACITY 3 +#define GD_SUPPRESS_PART_SCAN 5
struct mutex open_mutex; /* open/close mutex */ unsigned open_partitions; /* number of open partitions */