On Tue, 2010-12-21 at 23:00 -0500, Fred Isaman wrote:
> 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 <iisaman@xxxxxxxxxx>
> ---
> 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);
Isn't this debugged by now?
> + 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);
Ditto....
> + 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);
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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