On Dec 22, 2010, at 4:47 PM, Trond Myklebust wrote:
> 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....
OK, I'll remove those.
Fred
>
>> + 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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