Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-wi0-f171.google.com ([209.85.212.171]:48239 "EHLO mail-wi0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753635Ab3JBOcg (ORCPT ); Wed, 2 Oct 2013 10:32:36 -0400 Received: by mail-wi0-f171.google.com with SMTP id hm2so7385489wib.4 for ; Wed, 02 Oct 2013 07:32:34 -0700 (PDT) Message-ID: <524C2E80.8040407@primarydata.com> Date: Wed, 02 Oct 2013 17:32:32 +0300 From: Benny Halevy MIME-Version: 1.0 To: "J. Bruce Fields" CC: linux-nfs@vger.kernel.org Subject: Re: [PATCH RFC v0 10/49] pnfsd: use sbid hash table to map super_blocks to devid major identifiers References: <52447EA0.7070004@primarydata.com> <1380220831-13136-1-git-send-email-bhalevy@primarydata.com> <20131001221433.GB30994@pad.fieldses.org> In-Reply-To: <20131001221433.GB30994@pad.fieldses.org> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-nfs-owner@vger.kernel.org List-ID: On 2013-10-02 01:14, J. Bruce Fields wrote: > See previous comments. What guarantees these superblock pointers stay > good as long as they're in the cache? Currently, the dependency on nfsd.ko should hold them but that should go away. Trying to think about referencing svc_export instead, we use find_sbid_id to get to the superblock in nfsd4_getdevinfo since we have no current fh. And we need the superblock to call into the fs sb->s_pnfs_op->get_device_info later in nfsd4_encode_getdevinfo. Just to make sure, we can safely get to the sb via exp->ex_path.dentry->d_inode->i_sb right? Benny > > --b. > > On Thu, Sep 26, 2013 at 02:40:31PM -0400, Benny Halevy wrote: >> From: Benny Halevy >> >> Signed-off-by: Benny Halevy >> [pnfsd: alloc_sid should kmalloc a object not a pointer] >> Signed-off-by: Bian Naimeng >> Signed-off-by: Benny Halevy >> Signed-off-by: Benny Halevy >> --- >> 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 >> >> +#include "xdr4.h" >> + >> #endif /* LINUX_NFSD_PNFSD_H */ >> -- >> 1.8.3.1 >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >