From: Lachlan McIlroy Date: Mon, 6 May 2013 03:10:00 +0000 (-0400) Subject: ext4: limit group search loop for non-extent files X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=e6155736ad76b2070652745f9e54cdea3f0d8567;p=openwrt%2Fstaging%2Fblogic.git ext4: limit group search loop for non-extent files In the case where we are allocating for a non-extent file, we must limit the groups we allocate from to those below 2^32 blocks, and ext4_mb_regular_allocator() attempts to do this initially by putting a cap on ngroups for the subsequent search loop. However, the initial target group comes in from the allocation context (ac), and it may already be beyond the artificially limited ngroups. In this case, the limit if (group == ngroups) group = 0; at the top of the loop is never true, and the loop will run away. Catch this case inside the loop and reset the search to start at group 0. [sandeen@redhat.com: add commit msg & comments] Signed-off-by: Lachlan McIlroy Signed-off-by: Eric Sandeen Signed-off-by: "Theodore Ts'o" Cc: stable@vger.kernel.org --- diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index a11ea4d6164c..39d30f12d98d 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2105,7 +2105,11 @@ repeat: group = ac->ac_g_ex.fe_group; for (i = 0; i < ngroups; group++, i++) { - if (group == ngroups) + /* + * Artificially restricted ngroups for non-extent + * files makes group > ngroups possible on first loop. + */ + if (group >= ngroups) group = 0; /* This now checks without needing the buddy page */