linux-kernel - [PATCH v2 23/77] block/loop: convert to idr

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Message-ID: <20130207182642.GQ2875@htj.dyndns.org>
Date:	Thu, 7 Feb 2013 10:26:42 -0800
From:	Tejun Heo <tj@...nel.org>
To:	akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org
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@...nel.org>
Acked-by: Jens Axboe <axboe@...nel.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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