Return-Path: Received: from mx2.netapp.com ([216.240.18.37]:40898 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752220Ab0LVEBF (ORCPT ); Tue, 21 Dec 2010 23:01:05 -0500 From: Fred Isaman To: linux-nfs@vger.kernel.org Cc: Trond Myklebust Subject: [PATCH 11/15] pnfs: change lo refcounting to atomic_t Date: Tue, 21 Dec 2010 23:00:45 -0500 Message-Id: <1292990449-20057-12-git-send-email-iisaman@netapp.com> In-Reply-To: <1292990449-20057-1-git-send-email-iisaman@netapp.com> References: <1292990449-20057-1-git-send-email-iisaman@netapp.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: Content-Type: text/plain MIME-Version: 1.0 This will be required to allow us to grab reference outside of i_lock. While we are at it, make put_layout_hdr take the same argument as all the related functions. Signed-off-by: Fred Isaman --- fs/nfs/pnfs.c | 50 ++++++++++++++++++++++++++++---------------------- fs/nfs/pnfs.h | 4 ++-- 2 files changed, 30 insertions(+), 24 deletions(-) diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c index 970cc3b..53a0184 100644 --- a/fs/nfs/pnfs.c +++ b/fs/nfs/pnfs.c @@ -177,34 +177,40 @@ EXPORT_SYMBOL_GPL(pnfs_unregister_layoutdriver); * pNFS client layout cache */ +/* Need to hold i_lock if caller does not already hold reference */ static void -get_layout_hdr_locked(struct pnfs_layout_hdr *lo) +get_layout_hdr(struct pnfs_layout_hdr *lo) { - assert_spin_locked(&lo->plh_inode->i_lock); - lo->plh_refcount++; + atomic_inc(&lo->plh_refcount); } static void -put_layout_hdr_locked(struct pnfs_layout_hdr *lo) +destroy_layout_hdr(struct pnfs_layout_hdr *lo) { - assert_spin_locked(&lo->plh_inode->i_lock); - BUG_ON(lo->plh_refcount == 0); + dprintk("%s: freeing layout cache %p\n", __func__, lo); + BUG_ON(!list_empty(&lo->plh_layouts)); + NFS_I(lo->plh_inode)->layout = NULL; + kfree(lo); +} - lo->plh_refcount--; - if (!lo->plh_refcount) { - dprintk("%s: freeing layout cache %p\n", __func__, lo); - BUG_ON(!list_empty(&lo->plh_layouts)); - NFS_I(lo->plh_inode)->layout = NULL; - kfree(lo); - } +static void +put_layout_hdr_locked(struct pnfs_layout_hdr *lo) +{ + BUG_ON(atomic_read(&lo->plh_refcount) == 0); + if (atomic_dec_and_test(&lo->plh_refcount)) + destroy_layout_hdr(lo); } void -put_layout_hdr(struct inode *inode) +put_layout_hdr(struct pnfs_layout_hdr *lo) { - spin_lock(&inode->i_lock); - put_layout_hdr_locked(NFS_I(inode)->layout); - spin_unlock(&inode->i_lock); + struct inode *inode = lo->plh_inode; + + BUG_ON(atomic_read(&lo->plh_refcount) == 0); + if (atomic_dec_and_lock(&lo->plh_refcount, &inode->i_lock)) { + destroy_layout_hdr(lo); + spin_unlock(&inode->i_lock); + } } static void @@ -224,7 +230,7 @@ static void free_lseg(struct pnfs_layout_segment *lseg) BUG_ON(atomic_read(&lseg->pls_refcount) != 0); NFS_SERVER(ino)->pnfs_curr_ld->free_lseg(lseg); /* Matched by get_layout_hdr in pnfs_insert_layout */ - put_layout_hdr(ino); + put_layout_hdr(NFS_I(ino)->layout); } /* The use of tmp_list is necessary because pnfs_curr_ld->free_lseg @@ -481,7 +487,7 @@ pnfs_insert_layout(struct pnfs_layout_hdr *lo, __func__, lseg, lseg->pls_range.iomode, lseg->pls_range.offset, lseg->pls_range.length); } - get_layout_hdr_locked(lo); + get_layout_hdr(lo); dprintk("%s:Return\n", __func__); } @@ -494,7 +500,7 @@ alloc_init_layout_hdr(struct inode *ino) lo = kzalloc(sizeof(struct pnfs_layout_hdr), GFP_KERNEL); if (!lo) return NULL; - lo->plh_refcount = 1; + atomic_set(&lo->plh_refcount, 1); INIT_LIST_HEAD(&lo->plh_layouts); INIT_LIST_HEAD(&lo->plh_segs); lo->plh_inode = ino; @@ -609,7 +615,7 @@ pnfs_update_layout(struct inode *ino, goto out_unlock; atomic_inc(&lo->plh_outstanding); - get_layout_hdr_locked(lo); + get_layout_hdr(lo); if (list_empty(&lo->plh_segs)) { /* The lo must be on the clp list if there is any * chance of a CB_LAYOUTRECALL(FILE) coming in. @@ -632,7 +638,7 @@ pnfs_update_layout(struct inode *ino, spin_unlock(&ino->i_lock); } atomic_dec(&lo->plh_outstanding); - put_layout_hdr(ino); + put_layout_hdr(lo); out: dprintk("%s end, state 0x%lx lseg %p\n", __func__, nfsi->layout->plh_flags, lseg); diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h index 698380d..8aaab56 100644 --- a/fs/nfs/pnfs.h +++ b/fs/nfs/pnfs.h @@ -65,7 +65,7 @@ struct pnfs_layoutdriver_type { }; struct pnfs_layout_hdr { - unsigned long plh_refcount; + atomic_t plh_refcount; struct list_head plh_layouts; /* other client layouts */ struct list_head plh_segs; /* layout segments list */ nfs4_stateid plh_stateid; @@ -147,7 +147,7 @@ void unset_pnfs_layoutdriver(struct nfs_server *); int pnfs_layout_process(struct nfs4_layoutget *lgp); void pnfs_destroy_layout(struct nfs_inode *); void pnfs_destroy_all_layouts(struct nfs_client *); -void put_layout_hdr(struct inode *inode); +void put_layout_hdr(struct pnfs_layout_hdr *lo); int pnfs_choose_layoutget_stateid(nfs4_stateid *dst, struct pnfs_layout_hdr *lo, struct nfs4_state *open_state); -- 1.7.2.1