The patch titled
Subject: ocfs2: remove BUG_ON(!empty_extent) in __ocfs2_rotate_tree_left()
has been added to the -mm tree. Its filename is
ocfs2-remove-bug_onempty_extent-in-__ocfs2_rotate_tree_left.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ocfs2-remove-bug_onempty_extent-in-__ocfs2_rotate_tree_left.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ocfs2-remove-bug_onempty_extent-in-__ocfs2_rotate_tree_left.patch
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From: Xue jiufei <xuejiufei@xxxxxxxxxx>
Subject: ocfs2: remove BUG_ON(!empty_extent) in __ocfs2_rotate_tree_left()
ocfs2_rotate_tree_left() calls __ocfs2_rotate_tree_left() for left
rotation while non-rightmost path containing an empty extent in the leaf
block. __ocfs2_rotate_tree_left() returns -EAGAIN if right subtree having an
empty extent and pass the empty_extent_path to caller. The caller
ocfs2_rotate_tree_left() will restart rotation from the returned path.
It will trigger the BUG_ON(!ocfs2_is_empty_extent) when the et on disk
is as follows:
eb0 is the leaf block of path(say path_a) passed to
ocfs2_rotate_tree_left, which has an empty rec[0].
eb1 is the leaf block of path(say path_b) that just right to path_a, which
has no empty record.
eb2 is the leaf block of path(say path_c) that just right to path_b, which
has an empty rec[0]. And path_c is also the rightmost path.
Now we want to remove the empty rec[0] in eb0:
ocfs2_rotate_tree_left:
-> call __ocfs2_rotate_tree_left with path_a as its input *path*
-> call ocfs2_rotate_subtree_left with path_a as its input
*left_path* and path_b as its input *right_path*. it will move
rec[0] in eb1 to eb0, and rec[0] in eb0 is not empty now.
-> continue to call ocfs2_rotate_subtree_left with path_b as its
input *left_path* and path_c as its input *right_path*, and
return -EAGAIN because eb2 has an empty rec[0]
-> call __ocfs2_rotate_tree_left with path_c as it input, rotate all
records in eb2 to left and return 0.
-> call __ocfs2_rotate_tree_left with path_a as its input, and triggers
the BUG_ON(!ocfs2_is_empty_extent) as the rec[0] in eb0 is not empty.
So the BUG_ON() should be removed and return 0 if rec[0] is no longer an
empty extent.
Signed-off-by: joyce.xue <xuejiufei@xxxxxxxxxx>
Cc: Mark Fasheh <mfasheh@xxxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ocfs2/alloc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN fs/ocfs2/alloc.c~ocfs2-remove-bug_onempty_extent-in-__ocfs2_rotate_tree_left fs/ocfs2/alloc.c
--- a/fs/ocfs2/alloc.c~ocfs2-remove-bug_onempty_extent-in-__ocfs2_rotate_tree_left
+++ a/fs/ocfs2/alloc.c
@@ -2925,7 +2925,8 @@ static int __ocfs2_rotate_tree_left(hand
struct ocfs2_path *right_path = NULL;
struct super_block *sb = ocfs2_metadata_cache_get_super(et->et_ci);
- BUG_ON(!ocfs2_is_empty_extent(&(path_leaf_el(path)->l_recs[0])));
+ if (!ocfs2_is_empty_extent(&(path_leaf_el(path)->l_recs[0])))
+ return 0;
*empty_extent_path = NULL;
_
Patches currently in -mm which might be from xuejiufei@xxxxxxxxxx are
ocfs2-return-error-while-ocfs2_figure_merge_contig_type-failing.patch
ocfs2-remove-bug_onempty_extent-in-__ocfs2_rotate_tree_left.patch
ocfs2-dlm-fix-race-between-purge-and-get-lock-resource.patch
ocfs2-flush-inode-data-to-disk-and-free-inode-when-i_count-becomes-zero.patch
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