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

[Joakim Tjernlund]

David, pretty please :)

  Jocke
>
> 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
>
>
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