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Subject[PATCH v2 23/77] block/loop: convert to idr_alloc()
Subject: block/loop: convert to idr_alloc()

Convert to the much saner new idr interface.

v2: loop_add() treats -1 @i as request for any free ID while any other
negative trigger -EINVAL. The v1 conversion treated any negative
number as valid request for any free ID. While this doesn't make
any difference for in-kernel users, loop_add() is almost directly
visible to userland via LOOP_CTL_ADD and this behavior change is
userland-visible. Restore -EINVAL on < -1.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jens Axboe <axboe@kernel.dk>
---
Another mistake I noticed while auditing the conversions again. I
don't think this would actually affect anybody but no reason to change
the behavior.

Thanks.

drivers/block/loop.c | 21 +++++----------------
1 file changed, 5 insertions(+), 16 deletions(-)

--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1624,30 +1624,19 @@ static int loop_add(struct loop_device *
if (!lo)
goto out;

- if (!idr_pre_get(&loop_index_idr, GFP_KERNEL))
- goto out_free_dev;
-
+ /* allocate id, if @id >= 0, we're requesting that specific id */
if (i >= 0) {
- int m;
-
- /* create specific i in the index */
- err = idr_get_new_above(&loop_index_idr, lo, i, &m);
- if (err >= 0 && i != m) {
- idr_remove(&loop_index_idr, m);
+ err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
+ if (err == -ENOSPC)
err = -EEXIST;
- }
} else if (i == -1) {
- int m;
-
- /* get next free nr */
- err = idr_get_new(&loop_index_idr, lo, &m);
- if (err >= 0)
- i = m;
+ err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
} else {
err = -EINVAL;
}
if (err < 0)
goto out_free_dev;
+ i = err;

err = -ENOMEM;
lo->lo_queue = blk_alloc_queue(GFP_KERNEL);

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