See previous comments. What guarantees these superblock pointers stay
good as long as they're in the cache?
--b.
On Thu, Sep 26, 2013 at 02:40:31PM -0400, Benny Halevy wrote:
> From: Benny Halevy <bhalevy@xxxxxxxxxxx>
>
> Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
> [pnfsd: alloc_sid should kmalloc a object not a pointer]
> Signed-off-by: Bian Naimeng <biannm@xxxxxxxxxxxxxx>
> Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
> Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxxxxxx>
> ---
> fs/nfsd/nfs4pnfsd.c | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> fs/nfsd/pnfsd.h | 2 +
> 2 files changed, 122 insertions(+)
>
> diff --git a/fs/nfsd/nfs4pnfsd.c b/fs/nfsd/nfs4pnfsd.c
> index cb28207..9a7cbc9 100644
> --- a/fs/nfsd/nfs4pnfsd.c
> +++ b/fs/nfsd/nfs4pnfsd.c
> @@ -25,3 +25,123 @@
>
> #define NFSDDBG_FACILITY NFSDDBG_PNFS
>
> +static DEFINE_SPINLOCK(layout_lock);
> +
> +/* hash table for nfsd4_pnfs_deviceid.sbid */
> +#define SBID_HASH_BITS 8
> +#define SBID_HASH_SIZE (1 << SBID_HASH_BITS)
> +#define SBID_HASH_MASK (SBID_HASH_SIZE - 1)
> +
> +struct sbid_tracker {
> + u64 id;
> + struct super_block *sb;
> + struct list_head hash;
> +};
> +
> +static u64 current_sbid;
> +static struct list_head sbid_hashtbl[SBID_HASH_SIZE];
> +
> +static unsigned long
> +sbid_hashval(struct super_block *sb)
> +{
> + return hash_ptr(sb, SBID_HASH_BITS);
> +}
> +
> +static struct sbid_tracker *
> +alloc_sbid(void)
> +{
> + return kmalloc(sizeof(struct sbid_tracker), GFP_KERNEL);
> +}
> +
> +static void
> +destroy_sbid(struct sbid_tracker *sbid)
> +{
> + spin_lock(&layout_lock);
> + list_del(&sbid->hash);
> + spin_unlock(&layout_lock);
> + kfree(sbid);
> +}
> +
> +void
> +nfsd4_free_pnfs_slabs(void)
> +{
> + int i;
> + struct sbid_tracker *sbid;
> +
> + for (i = 0; i < SBID_HASH_SIZE; i++) {
> + while (!list_empty(&sbid_hashtbl[i])) {
> + sbid = list_first_entry(&sbid_hashtbl[i],
> + struct sbid_tracker,
> + hash);
> + destroy_sbid(sbid);
> + }
> + }
> +}
> +
> +int
> +nfsd4_init_pnfs_slabs(void)
> +{
> + int i;
> +
> + for (i = 0; i < SBID_HASH_SIZE; i++)
> + INIT_LIST_HEAD(&sbid_hashtbl[i]);
> +
> + return 0;
> +}
> +
> +static u64
> +alloc_init_sbid(struct super_block *sb)
> +{
> + struct sbid_tracker *sbid;
> + struct sbid_tracker *new = alloc_sbid();
> + unsigned long hash_idx = sbid_hashval(sb);
> + u64 id = 0;
> +
> + if (likely(new)) {
> + spin_lock(&layout_lock);
> + id = ++current_sbid;
> + new->id = (id << SBID_HASH_BITS) | (hash_idx & SBID_HASH_MASK);
> + id = new->id;
> + BUG_ON(id == 0);
> + new->sb = sb;
> +
> + list_for_each_entry (sbid, &sbid_hashtbl[hash_idx], hash)
> + if (sbid->sb == sb) {
> + kfree(new);
> + id = sbid->id;
> + spin_unlock(&layout_lock);
> + return id;
> + }
> + list_add(&new->hash, &sbid_hashtbl[hash_idx]);
> + spin_unlock(&layout_lock);
> + }
> + return id;
> +}
> +
> +static u64
> +find_create_sbid(struct super_block *sb)
> +{
> + struct sbid_tracker *sbid;
> + unsigned long hash_idx = sbid_hashval(sb);
> + int pos = 0;
> + u64 id = 0;
> +
> + spin_lock(&layout_lock);
> + list_for_each_entry (sbid, &sbid_hashtbl[hash_idx], hash) {
> + pos++;
> + if (sbid->sb != sb)
> + continue;
> + if (pos > 1) {
> + list_del(&sbid->hash);
> + list_add(&sbid->hash, &sbid_hashtbl[hash_idx]);
> + }
> + id = sbid->id;
> + break;
> + }
> + spin_unlock(&layout_lock);
> +
> + if (!id)
> + id = alloc_init_sbid(sb);
> +
> + return id;
> +}
> diff --git a/fs/nfsd/pnfsd.h b/fs/nfsd/pnfsd.h
> index 7c46791..29ea2e7 100644
> --- a/fs/nfsd/pnfsd.h
> +++ b/fs/nfsd/pnfsd.h
> @@ -36,4 +36,6 @@
>
> #include <linux/nfsd/nfsd4_pnfs.h>
>
> +#include "xdr4.h"
> +
> #endif /* LINUX_NFSD_PNFSD_H */
> --
> 1.8.3.1
>
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