Commit f1167009 authored by Niu Yawei's avatar Niu Yawei Committed by Theodore Ts'o

ext4: fix race in ext4_mb_add_n_trim()

In ext4_mb_add_n_trim(), lg_prealloc_lock should be taken when
changing the lg_prealloc_list.
Signed-off-by: default avatarNiu Yawei <yawei.niu@intel.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
parent 87e69873
...@@ -4136,7 +4136,7 @@ static void ext4_mb_add_n_trim(struct ext4_allocation_context *ac) ...@@ -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 */ /* The max size of hash table is PREALLOC_TB_SIZE */
order = PREALLOC_TB_SIZE - 1; order = PREALLOC_TB_SIZE - 1;
/* Add the prealloc space to lg */ /* 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], list_for_each_entry_rcu(tmp_pa, &lg->lg_prealloc_list[order],
pa_inode_list) { pa_inode_list) {
spin_lock(&tmp_pa->pa_lock); spin_lock(&tmp_pa->pa_lock);
...@@ -4160,12 +4160,12 @@ static void ext4_mb_add_n_trim(struct ext4_allocation_context *ac) ...@@ -4160,12 +4160,12 @@ static void ext4_mb_add_n_trim(struct ext4_allocation_context *ac)
if (!added) if (!added)
list_add_tail_rcu(&pa->pa_inode_list, list_add_tail_rcu(&pa->pa_inode_list,
&lg->lg_prealloc_list[order]); &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 */ /* Now trim the list to be not more than 8 elements */
if (lg_prealloc_count > 8) { if (lg_prealloc_count > 8) {
ext4_mb_discard_lg_preallocations(sb, lg, ext4_mb_discard_lg_preallocations(sb, lg,
order, lg_prealloc_count); order, lg_prealloc_count);
return; return;
} }
return ; return ;
......
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