Re: jbd2: Convert jbd2_slab_create_sem to mutex

From: Andrew Morton
Date: Sat Oct 16 2010 - 17:09:33 EST


On Sat, 16 Oct 2010 22:34:39 +0200 (CEST) Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:

> jbd2_slab_create_sem is used as a mutex, so make it one.
>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> ---
> fs/jbd2/journal.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> Index: linux-next/fs/jbd2/journal.c
> ===================================================================
> --- linux-next.orig/fs/jbd2/journal.c
> +++ linux-next/fs/jbd2/journal.c
> @@ -1838,7 +1838,7 @@ size_t journal_tag_bytes(journal_t *jour
> */
> #define JBD2_MAX_SLABS 8
> static struct kmem_cache *jbd2_slab[JBD2_MAX_SLABS];
> -static DECLARE_MUTEX(jbd2_slab_create_sem);
> +static DEFINE_MUTEX(jbd2_slab_create_mutex);
>
> static const char *jbd2_slab_names[JBD2_MAX_SLABS] = {
> "jbd2_1k", "jbd2_2k", "jbd2_4k", "jbd2_8k",
> @@ -1870,16 +1870,16 @@ static int jbd2_journal_create_slab(size
>
> if (unlikely(i < 0))
> i = 0;
> - down(&jbd2_slab_create_sem);
> + mutex_lock(&jbd2_slab_create_mutex);
> if (jbd2_slab[i]) {
> - up(&jbd2_slab_create_sem);
> + mutex_unlock(&jbd2_slab_create_mutex);
> return 0; /* Already created */
> }
>
> slab_size = 1 << (i+10);
> jbd2_slab[i] = kmem_cache_create(jbd2_slab_names[i], slab_size,
> slab_size, 0, NULL);
> - up(&jbd2_slab_create_sem);
> + mutex_unlock(&jbd2_slab_create_mutex);
> if (!jbd2_slab[i]) {
> printk(KERN_EMERG "JBD2: no memory for jbd2_slab cache\n");
> return -ENOMEM;

gad, whodidthat.

We may as well make it local to jbd2_journal_create_slab() also.
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