Patch "ext4: fix race in ext4_mb_add_n_trim()" has been added to the 3.8-stable tree

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This is a note to let you know that I've just added the patch titled

    ext4: fix race in ext4_mb_add_n_trim()

to the 3.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ext4-fix-race-in-ext4_mb_add_n_trim.patch
and it can be found in the queue-3.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From f1167009711032b0d747ec89a632a626c901a1ad Mon Sep 17 00:00:00 2001
From: Niu Yawei <yawei.niu@xxxxxxxxx>
Date: Fri, 1 Feb 2013 21:31:27 -0500
Subject: ext4: fix race in ext4_mb_add_n_trim()

From: Niu Yawei <yawei.niu@xxxxxxxxx>

commit f1167009711032b0d747ec89a632a626c901a1ad upstream.

In ext4_mb_add_n_trim(), lg_prealloc_lock should be taken when
changing the lg_prealloc_list.

Signed-off-by: Niu Yawei <yawei.niu@xxxxxxxxx>
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/ext4/mballoc.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4136,7 +4136,7 @@ static void ext4_mb_add_n_trim(struct ex
 		/* The max size of hash table is PREALLOC_TB_SIZE */
 		order = PREALLOC_TB_SIZE - 1;
 	/* Add the prealloc space to lg */
-	rcu_read_lock();
+	spin_lock(&lg->lg_prealloc_lock);
 	list_for_each_entry_rcu(tmp_pa, &lg->lg_prealloc_list[order],
 						pa_inode_list) {
 		spin_lock(&tmp_pa->pa_lock);
@@ -4160,12 +4160,12 @@ static void ext4_mb_add_n_trim(struct ex
 	if (!added)
 		list_add_tail_rcu(&pa->pa_inode_list,
 					&lg->lg_prealloc_list[order]);
-	rcu_read_unlock();
+	spin_unlock(&lg->lg_prealloc_lock);
 
 	/* Now trim the list to be not more than 8 elements */
 	if (lg_prealloc_count > 8) {
 		ext4_mb_discard_lg_preallocations(sb, lg,
-						order, lg_prealloc_count);
+						  order, lg_prealloc_count);
 		return;
 	}
 	return ;


Patches currently in stable-queue which might be from yawei.niu@xxxxxxxxx are

queue-3.8/ext4-fix-race-in-ext4_mb_add_n_trim.patch
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