From: Niu Yawei Date: Sat, 2 Feb 2013 02:31:27 +0000 (-0500) Subject: ext4: fix race in ext4_mb_add_n_trim() X-Git-Tag: v3.8.2~28 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=8a6a8f044a39224fa29b0a0f11092858258194e0;p=karo-tx-linux.git ext4: fix race in ext4_mb_add_n_trim() commit f1167009711032b0d747ec89a632a626c901a1ad upstream. In ext4_mb_add_n_trim(), lg_prealloc_lock should be taken when changing the lg_prealloc_list. Signed-off-by: Niu Yawei Signed-off-by: "Theodore Ts'o" Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 1bf6fe785c4f..061727acd990 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4136,7 +4136,7 @@ static void ext4_mb_add_n_trim(struct ext4_allocation_context *ac) /* The max size of hash table is PREALLOC_TB_SIZE */ order = PREALLOC_TB_SIZE - 1; /* Add the prealloc space to lg */ - rcu_read_lock(); + spin_lock(&lg->lg_prealloc_lock); list_for_each_entry_rcu(tmp_pa, &lg->lg_prealloc_list[order], pa_inode_list) { spin_lock(&tmp_pa->pa_lock); @@ -4160,12 +4160,12 @@ static void ext4_mb_add_n_trim(struct ext4_allocation_context *ac) if (!added) list_add_tail_rcu(&pa->pa_inode_list, &lg->lg_prealloc_list[order]); - rcu_read_unlock(); + spin_unlock(&lg->lg_prealloc_lock); /* Now trim the list to be not more than 8 elements */ if (lg_prealloc_count > 8) { ext4_mb_discard_lg_preallocations(sb, lg, - order, lg_prealloc_count); + order, lg_prealloc_count); return; } return ;