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Subject[PATCH 3/4] staging/lustre/llite: avoid nonatomic memory alloc under spinlock
Date
From: Lai Siyao <lai.siyao@intel.com>

ll_intent_drop_lock() may sleep in memory allocation, which
should not be called inside spinlock.

Signed-off-by: Lai Siyao <lai.siyao@intel.com>
Signed-off-by: Jian Yu <jian.yu@intel.com>
Reviewed-on: http://review.whamcloud.com/10674
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-2272
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
---
drivers/staging/lustre/lustre/llite/statahead.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/lustre/lustre/llite/statahead.c b/drivers/staging/lustre/lustre/llite/statahead.c
index fe732fa..b75562c 100644
--- a/drivers/staging/lustre/lustre/llite/statahead.c
+++ b/drivers/staging/lustre/lustre/llite/statahead.c
@@ -706,11 +706,21 @@ static int ll_statahead_interpret(struct ptlrpc_request *req,
struct ll_inode_info *lli = ll_i2info(dir);
struct ll_statahead_info *sai = NULL;
struct ll_sa_entry *entry;
+ __u64 handle = 0;
int wakeup;

if (it_disposition(it, DISP_LOOKUP_NEG))
rc = -ENOENT;

+ if (rc == 0) {
+ /* release ibits lock ASAP to avoid deadlock when statahead
+ * thread enqueues lock on parent in readdir and another
+ * process enqueues lock on child with parent lock held, eg.
+ * unlink. */
+ handle = it->d.lustre.it_lock_handle;
+ ll_intent_drop_lock(it);
+ }
+
spin_lock(&lli->lli_sa_lock);
/* stale entry */
if (unlikely(lli->lli_sai == NULL ||
@@ -745,8 +755,7 @@ static int ll_statahead_interpret(struct ptlrpc_request *req,
* when statahead thread tries to enqueue lock on parent
* for readpage and other tries to enqueue lock on child
* with parent's lock held, for example: unlink. */
- entry->se_handle = it->d.lustre.it_lock_handle;
- ll_intent_drop_lock(it);
+ entry->se_handle = handle;
wakeup = sa_received_empty(sai);
list_add_tail(&entry->se_list,
&sai->sai_entries_received);
--
2.1.0


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