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authorLarry Chen <lchen@suse.com>2018-11-30 14:08:56 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-11-30 14:56:13 -0800
commite21e57445a64598b29a6f629688f9b9a39e7242a (patch)
tree7113749d5accde51794de92c4f0f96eabd76a957
parent08be37b798921af207e78082fe261a6ca8be5024 (diff)
ocfs2: fix deadlock caused by ocfs2_defrag_extent()
ocfs2_defrag_extent may fall into deadlock. ocfs2_ioctl_move_extents ocfs2_ioctl_move_extents ocfs2_move_extents ocfs2_defrag_extent ocfs2_lock_allocators_move_extents ocfs2_reserve_clusters inode_lock GLOBAL_BITMAP_SYSTEM_INODE __ocfs2_flush_truncate_log inode_lock GLOBAL_BITMAP_SYSTEM_INODE As backtrace shows above, ocfs2_reserve_clusters() will call inode_lock against the global bitmap if local allocator has not sufficient cluters. Once global bitmap could meet the demand, ocfs2_reserve_cluster will return success with global bitmap locked. After ocfs2_reserve_cluster(), if truncate log is full, __ocfs2_flush_truncate_log() will definitely fall into deadlock because it needs to inode_lock global bitmap, which has already been locked. To fix this bug, we could remove from ocfs2_lock_allocators_move_extents() the code which intends to lock global allocator, and put the removed code after __ocfs2_flush_truncate_log(). ocfs2_lock_allocators_move_extents() is referred by 2 places, one is here, the other does not need the data allocator context, which means this patch does not affect the caller so far. Link: http://lkml.kernel.org/r/20181101071422.14470-1-lchen@suse.com Signed-off-by: Larry Chen <lchen@suse.com> Reviewed-by: Changwei Ge <ge.changwei@h3c.com> Cc: Mark Fasheh <mark@fasheh.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Junxiao Bi <junxiao.bi@oracle.com> Cc: Joseph Qi <jiangqi903@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/ocfs2/move_extents.c47
1 files changed, 26 insertions, 21 deletions
diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c
index 3f1685d7d43b..1565dd8e8856 100644
--- a/fs/ocfs2/move_extents.c
+++ b/fs/ocfs2/move_extents.c
@@ -157,18 +157,14 @@ out:
}
/*
- * lock allocators, and reserving appropriate number of bits for
- * meta blocks and data clusters.
- *
- * in some cases, we don't need to reserve clusters, just let data_ac
- * be NULL.
+ * lock allocator, and reserve appropriate number of bits for
+ * meta blocks.
*/
-static int ocfs2_lock_allocators_move_extents(struct inode *inode,
+static int ocfs2_lock_meta_allocator_move_extents(struct inode *inode,
struct ocfs2_extent_tree *et,
u32 clusters_to_move,
u32 extents_to_split,
struct ocfs2_alloc_context **meta_ac,
- struct ocfs2_alloc_context **data_ac,
int extra_blocks,
int *credits)
{
@@ -193,13 +189,6 @@ static int ocfs2_lock_allocators_move_extents(struct inode *inode,
goto out;
}
- if (data_ac) {
- ret = ocfs2_reserve_clusters(osb, clusters_to_move, data_ac);
- if (ret) {
- mlog_errno(ret);
- goto out;
- }
- }
*credits += ocfs2_calc_extend_credits(osb->sb, et->et_root_el);
@@ -259,10 +248,10 @@ static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
}
}
- ret = ocfs2_lock_allocators_move_extents(inode, &context->et, *len, 1,
- &context->meta_ac,
- &context->data_ac,
- extra_blocks, &credits);
+ ret = ocfs2_lock_meta_allocator_move_extents(inode, &context->et,
+ *len, 1,
+ &context->meta_ac,
+ extra_blocks, &credits);
if (ret) {
mlog_errno(ret);
goto out;
@@ -285,6 +274,21 @@ static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
}
}
+ /*
+ * Make sure ocfs2_reserve_cluster is called after
+ * __ocfs2_flush_truncate_log, otherwise, dead lock may happen.
+ *
+ * If ocfs2_reserve_cluster is called
+ * before __ocfs2_flush_truncate_log, dead lock on global bitmap
+ * may happen.
+ *
+ */
+ ret = ocfs2_reserve_clusters(osb, *len, &context->data_ac);
+ if (ret) {
+ mlog_errno(ret);
+ goto out_unlock_mutex;
+ }
+
handle = ocfs2_start_trans(osb, credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
@@ -617,9 +621,10 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
}
}
- ret = ocfs2_lock_allocators_move_extents(inode, &context->et, len, 1,
- &context->meta_ac,
- NULL, extra_blocks, &credits);
+ ret = ocfs2_lock_meta_allocator_move_extents(inode, &context->et,
+ len, 1,
+ &context->meta_ac,
+ extra_blocks, &credits);
if (ret) {
mlog_errno(ret);
goto out;