From 1fd8bc7cd889bd73d07a83cb32d674ac68f99153 Mon Sep 17 00:00:00 2001 From: Yang Erkun Date: Sat, 14 Dec 2024 17:30:05 +0800 Subject: [PATCH] maple_tree: reload mas before the second call for mas_empty_area Change the LONG_MAX in simple_offset_add to 1024, and do latter: [root@fedora ~]# mkdir /tmp/dir [root@fedora ~]# for i in {1..1024}; do touch /tmp/dir/$i; done touch: cannot touch '/tmp/dir/1024': Device or resource busy [root@fedora ~]# rm /tmp/dir/123 [root@fedora ~]# touch /tmp/dir/1024 [root@fedora ~]# rm /tmp/dir/100 [root@fedora ~]# touch /tmp/dir/1025 touch: cannot touch '/tmp/dir/1025': Device or resource busy After we delete file 100, actually this is a empty entry, but the latter create failed unexpected. mas_alloc_cyclic has two chance to find empty entry. First find the entry with range range_lo and range_hi, if no empty entry exist, and range_lo > min, retry find with range min and range_hi. However, the first call mas_empty_area may mark mas as EBUSY, and the second call for mas_empty_area will return false directly. Fix this by reload mas before second call for mas_empty_area. [Liam.Howlett@Oracle.com: fix mas_alloc_cyclic() second search] Link: https://lore.kernel.org/all/20241216060600.287B4C4CED0@smtp.kernel.org/ Link: https://lkml.kernel.org/r/20241216190113.1226145-2-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20241214093005.72284-1-yangerkun@huaweicloud.com Fixes: 9b6713cc7522 ("maple_tree: Add mtree_alloc_cyclic()") Signed-off-by: Yang Erkun Signed-off-by: Liam R. Howlett Cc: Christian Brauner Cc: Chuck Lever says: Cc: Liam R. Howlett Cc: Signed-off-by: Andrew Morton --- lib/maple_tree.c | 1 + 1 file changed, 1 insertion(+) diff --git a/lib/maple_tree.c b/lib/maple_tree.c index d0ae808f3a149..047397136f15b 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -4354,6 +4354,7 @@ int mas_alloc_cyclic(struct ma_state *mas, unsigned long *startp, ret = 1; } if (ret < 0 && range_lo > min) { + mas_reset(mas); ret = mas_empty_area(mas, min, range_hi, 1); if (ret == 0) ret = 1;