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Subject[patch 093/114] ext4: Fix lockdep warning

2.6.28-stable review patch. If anyone has any objections, please let us know.

------------------
From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

(cherry picked from commit ba4439165f0f0d25b2fe065cf0c1ff8130b802eb)

We should not call ext4_mb_add_n_trim while holding alloc_semp.

=============================================
[ INFO: possible recursive locking detected ]
2.6.29-rc4-git1-dirty #124
---------------------------------------------
ffsb/3116 is trying to acquire lock:
(&meta_group_info[i]->alloc_sem){----}, at: [<ffffffff8035a6e8>]
ext4_mb_load_buddy+0xd2/0x343
but task is already holding lock:
(&meta_group_info[i]->alloc_sem){----}, at: [<ffffffff8035a6e8>]
ext4_mb_load_buddy+0xd2/0x343
http://bugzilla.kernel.org/show_bug.cgi?id=12672

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/ext4/mballoc.c | 29 ++++++++++++++++-------------
1 file changed, 16 insertions(+), 13 deletions(-)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4456,23 +4456,26 @@ static int ext4_mb_release_context(struc
pa->pa_free -= ac->ac_b_ex.fe_len;
pa->pa_len -= ac->ac_b_ex.fe_len;
spin_unlock(&pa->pa_lock);
- /*
- * We want to add the pa to the right bucket.
- * Remove it from the list and while adding
- * make sure the list to which we are adding
- * doesn't grow big.
- */
- if (likely(pa->pa_free)) {
- spin_lock(pa->pa_obj_lock);
- list_del_rcu(&pa->pa_inode_list);
- spin_unlock(pa->pa_obj_lock);
- ext4_mb_add_n_trim(ac);
- }
}
- ext4_mb_put_pa(ac, ac->ac_sb, pa);
}
if (ac->alloc_semp)
up_read(ac->alloc_semp);
+ if (pa) {
+ /*
+ * We want to add the pa to the right bucket.
+ * Remove it from the list and while adding
+ * make sure the list to which we are adding
+ * doesn't grow big. We need to release
+ * alloc_semp before calling ext4_mb_add_n_trim()
+ */
+ if (pa->pa_linear && likely(pa->pa_free)) {
+ spin_lock(pa->pa_obj_lock);
+ list_del_rcu(&pa->pa_inode_list);
+ spin_unlock(pa->pa_obj_lock);
+ ext4_mb_add_n_trim(ac);
+ }
+ ext4_mb_put_pa(ac, ac->ac_sb, pa);
+ }
if (ac->ac_bitmap_page)
page_cache_release(ac->ac_bitmap_page);
if (ac->ac_buddy_page)



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