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>
This commit is contained in:
parent
08be37b798
commit
e21e57445a
fs/ocfs2
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@ -157,18 +157,14 @@ out:
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}
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}
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/*
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/*
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* lock allocators, and reserving appropriate number of bits for
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* lock allocator, and reserve appropriate number of bits for
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* meta blocks and data clusters.
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* meta blocks.
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*
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* in some cases, we don't need to reserve clusters, just let data_ac
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* be NULL.
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*/
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*/
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static int ocfs2_lock_allocators_move_extents(struct inode *inode,
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static int ocfs2_lock_meta_allocator_move_extents(struct inode *inode,
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struct ocfs2_extent_tree *et,
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struct ocfs2_extent_tree *et,
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u32 clusters_to_move,
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u32 clusters_to_move,
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u32 extents_to_split,
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u32 extents_to_split,
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struct ocfs2_alloc_context **meta_ac,
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struct ocfs2_alloc_context **meta_ac,
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struct ocfs2_alloc_context **data_ac,
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int extra_blocks,
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int extra_blocks,
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int *credits)
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int *credits)
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{
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{
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@ -193,13 +189,6 @@ static int ocfs2_lock_allocators_move_extents(struct inode *inode,
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goto out;
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goto out;
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}
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}
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if (data_ac) {
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ret = ocfs2_reserve_clusters(osb, clusters_to_move, data_ac);
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if (ret) {
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mlog_errno(ret);
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goto out;
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}
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}
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*credits += ocfs2_calc_extend_credits(osb->sb, et->et_root_el);
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*credits += ocfs2_calc_extend_credits(osb->sb, et->et_root_el);
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@ -259,10 +248,10 @@ static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
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}
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}
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}
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}
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ret = ocfs2_lock_allocators_move_extents(inode, &context->et, *len, 1,
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ret = ocfs2_lock_meta_allocator_move_extents(inode, &context->et,
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&context->meta_ac,
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*len, 1,
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&context->data_ac,
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&context->meta_ac,
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extra_blocks, &credits);
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extra_blocks, &credits);
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if (ret) {
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if (ret) {
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mlog_errno(ret);
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mlog_errno(ret);
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goto out;
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goto out;
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@ -285,6 +274,21 @@ static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
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}
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}
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}
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}
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/*
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* Make sure ocfs2_reserve_cluster is called after
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* __ocfs2_flush_truncate_log, otherwise, dead lock may happen.
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*
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* If ocfs2_reserve_cluster is called
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* before __ocfs2_flush_truncate_log, dead lock on global bitmap
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* may happen.
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*
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*/
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ret = ocfs2_reserve_clusters(osb, *len, &context->data_ac);
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if (ret) {
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mlog_errno(ret);
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goto out_unlock_mutex;
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}
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handle = ocfs2_start_trans(osb, credits);
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handle = ocfs2_start_trans(osb, credits);
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if (IS_ERR(handle)) {
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if (IS_ERR(handle)) {
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ret = PTR_ERR(handle);
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ret = PTR_ERR(handle);
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@ -617,9 +621,10 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
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}
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}
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}
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}
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ret = ocfs2_lock_allocators_move_extents(inode, &context->et, len, 1,
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ret = ocfs2_lock_meta_allocator_move_extents(inode, &context->et,
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&context->meta_ac,
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len, 1,
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NULL, extra_blocks, &credits);
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&context->meta_ac,
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extra_blocks, &credits);
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if (ret) {
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if (ret) {
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mlog_errno(ret);
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mlog_errno(ret);
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goto out;
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goto out;
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