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btrfs: scrub: replace max_t()/min_t() with clamp() in scrub_throttle_dev_io()

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[ Upstream commit a7f3dfb8293c4cee99743132d69863a92e8f4875 ]

Replace max_t() followed by min_t() with a single clamp().

As was pointed by David Laight in
https://lore.kernel.org/linux-btrfs/20250906122458.75dfc8f0@pumpkin/
the calculation may overflow u32 when the input value is too large, so
clamp_t() is not used.  In practice the expected values are in range of
megabytes to gigabytes (throughput limit) so the bug would not happen.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: David Sterba <dsterba@suse.com>
[ Use clamp() and add explanation. ]
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Thorsten Blum
2025-09-01 17:01:44 +02:00
committed by Greg Kroah-Hartman
parent 9c50fde908
commit 8e36ab6903
1 changed files with 1 additions and 2 deletions
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fs/btrfs/scrub.c
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@@ -1369,8 +1369,7 @@ static void scrub_throttle_dev_io(struct scrub_ctx *sctx, struct btrfs_device *d
* Slice is divided into intervals when the IO is submitted, adjust by
* bwlimit and maximum of 64 intervals.
*/
div = max_t(u32, 1, (u32)(bwlimit / (16 * 1024 * 1024)));
div = min_t(u32, 64, div);
div = clamp(bwlimit / (16 * 1024 * 1024), 1, 64);
/* Start new epoch, set deadline */
now = ktime_get();