loop: move updating lo_flags out of loop_set_status_from_info

While loop_configure simplify assigns the flags passed in by userspace,
loop_set_status only looks at the two changeable flags, and currently
has to do a complicate dance to implement that.

Move assign lo->lo_flags out of loop_set_status_from_info into the
callers and thus drastically simplify the lo_flags handling in
loop_set_status.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250110073750.1582447-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 15e486baa223a5f0a40758007d53fb30b4a65c13..6ea729cdce711ce1717d8d782025d335046a06e0 100644 (file)
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -971,7 +971,6 @@ loop_set_status_from_info(struct loop_device *lo,
 
        memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
        lo->lo_file_name[LO_NAME_SIZE-1] = 0;
-       lo->lo_flags = info->lo_flags;
        return 0;
 }
 
@@ -1069,6 +1068,7 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode,
        error = loop_set_status_from_info(lo, &config->info);
        if (error)
                goto out_unlock;
+       lo->lo_flags = config->info.lo_flags;
 
        if (!(file->f_mode & FMODE_WRITE) || !(mode & BLK_OPEN_WRITE) ||
            !file->f_op->write_iter)
@@ -1258,7 +1258,6 @@ static int
 loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
 {
        int err;
-       int prev_lo_flags;
        bool partscan = false;
        bool size_changed = false;
 
@@ -1280,18 +1279,16 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
        /* I/O need to be drained during transfer transition */
        blk_mq_freeze_queue(lo->lo_queue);
 
-       prev_lo_flags = lo->lo_flags;
-
        err = loop_set_status_from_info(lo, info);
        if (err)
                goto out_unfreeze;
 
-       /* Mask out flags that can't be set using LOOP_SET_STATUS. */
-       lo->lo_flags &= LOOP_SET_STATUS_SETTABLE_FLAGS;
-       /* For those flags, use the previous values instead */
-       lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_SETTABLE_FLAGS;
-       /* For flags that can't be cleared, use previous values too */
-       lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_CLEARABLE_FLAGS;
+       partscan = !(lo->lo_flags & LO_FLAGS_PARTSCAN) &&
+               (info->lo_flags & LO_FLAGS_PARTSCAN);
+
+       lo->lo_flags &= ~(LOOP_SET_STATUS_SETTABLE_FLAGS |
+                         LOOP_SET_STATUS_CLEARABLE_FLAGS);
+       lo->lo_flags |= (info->lo_flags & LOOP_SET_STATUS_SETTABLE_FLAGS);
 
        if (size_changed) {
                loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit,
@@ -1304,12 +1301,8 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
 
 out_unfreeze:
        blk_mq_unfreeze_queue(lo->lo_queue);
-
-       if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) &&
-            !(prev_lo_flags & LO_FLAGS_PARTSCAN)) {
+       if (partscan)
                clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
-               partscan = true;
-       }
 out_unlock:
        mutex_unlock(&lo->lo_mutex);
        if (partscan)