[PATCH] jffs2: Fix serious write stall due to erase

[Joakim Tjernlund]

Drop the alloc_sem before erasing flash in
jffs2_garbage_collect_pass().
Otherwise writes are put on hold until the erase
has finised.

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund at transmode.se>
---

 I am fairly sure it is safe to unlock the alloc_sem before
 calling jffs2_erase_pending_blocks(). Extra confirmation
 would be great though.

 This problem was introduced in 2.6.35

 fs/jffs2/gc.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/jffs2/gc.c b/fs/jffs2/gc.c
index f5e96bd..b5f7175 100644
--- a/fs/jffs2/gc.c
+++ b/fs/jffs2/gc.c
@@ -218,13 +218,14 @@ int jffs2_garbage_collect_pass(struct jffs2_sb_info *c)
 	if (!list_empty(&c->erase_complete_list) ||
 	    !list_empty(&c->erase_pending_list)) {
 		spin_unlock(&c->erase_completion_lock);
+		mutex_unlock(&c->alloc_sem);
 		D1(printk(KERN_DEBUG "jffs2_garbage_collect_pass() erasing pending blocks\n"));
-		if (jffs2_erase_pending_blocks(c, 1)) {
-			mutex_unlock(&c->alloc_sem);
+		if (jffs2_erase_pending_blocks(c, 1))
 			return 0;
-		}
+
 		D1(printk(KERN_DEBUG "No progress from erasing blocks; doing GC anyway\n"));
 		spin_lock(&c->erase_completion_lock);
+		mutex_lock(&c->alloc_sem);
 	}
 
 	/* First, work out which block we're garbage-collecting */
-- 
1.7.2.2