Commit 13c13a6a authored by Trond Myklebust's avatar Trond Myklebust
Browse files

pNFS: Fix missing layoutreturn calls 



The layoutreturn code currently relies on pnfs_put_lseg() to initiate the
RPC call when conditions are right. A problem arises when we want to
free the layout segment from inside an inode->i_lock section (e.g. in
pnfs_clear_request_commit()), since we cannot sleep.

The workaround is to move the actual call to pnfs_send_layoutreturn()
to pnfs_put_layout_hdr(), which doesn't have this restriction.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent 92e963f5

fs/nfs/pnfs.c

+56 −62
Original line number Diff line number Diff line
@@ -52,9 +52,7 @@ static DEFINE_SPINLOCK(pnfs_spinlock); 
 */

static LIST_HEAD(pnfs_modules_tbl);



static int

pnfs_send_layoutreturn(struct pnfs_layout_hdr *lo, const nfs4_stateid *stateid,

		       enum pnfs_iomode iomode, bool sync);

static void pnfs_layoutreturn_before_put_layout_hdr(struct pnfs_layout_hdr *lo);



/* Return the registered pnfs layout driver module matching given id */

static struct pnfs_layoutdriver_type *
@@ -243,6 +241,8 @@ pnfs_put_layout_hdr(struct pnfs_layout_hdr *lo) 
{

	struct inode *inode = lo->plh_inode;



	pnfs_layoutreturn_before_put_layout_hdr(lo);



	if (atomic_dec_and_lock(&lo->plh_refcount, &inode->i_lock)) {

		if (!list_empty(&lo->plh_segs))

			WARN_ONCE(1, "NFS: BUG unfreed layout segments.\n");
@@ -345,58 +345,6 @@ pnfs_layout_remove_lseg(struct pnfs_layout_hdr *lo, 
	rpc_wake_up(&NFS_SERVER(inode)->roc_rpcwaitq);

}



/* Return true if layoutreturn is needed */

static bool

pnfs_layout_need_return(struct pnfs_layout_hdr *lo,

			struct pnfs_layout_segment *lseg)

{

	struct pnfs_layout_segment *s;



	if (!test_and_clear_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags))

		return false;



	list_for_each_entry(s, &lo->plh_segs, pls_list)

		if (s != lseg && test_bit(NFS_LSEG_LAYOUTRETURN, &s->pls_flags))

			return false;



	return true;

}



static bool

pnfs_prepare_layoutreturn(struct pnfs_layout_hdr *lo)

{

	if (test_and_set_bit(NFS_LAYOUT_RETURN, &lo->plh_flags))

		return false;

	lo->plh_return_iomode = 0;

	pnfs_get_layout_hdr(lo);

	clear_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE, &lo->plh_flags);

	return true;

}



static void pnfs_layoutreturn_before_put_lseg(struct pnfs_layout_segment *lseg,

		struct pnfs_layout_hdr *lo, struct inode *inode)

{

	lo = lseg->pls_layout;

	inode = lo->plh_inode;



	spin_lock(&inode->i_lock);

	if (pnfs_layout_need_return(lo, lseg)) {

		nfs4_stateid stateid;

		enum pnfs_iomode iomode;

		bool send;



		nfs4_stateid_copy(&stateid, &lo->plh_stateid);

		iomode = lo->plh_return_iomode;

		send = pnfs_prepare_layoutreturn(lo);

		spin_unlock(&inode->i_lock);

		if (send) {

			/* Send an async layoutreturn so we dont deadlock */

			pnfs_send_layoutreturn(lo, &stateid, iomode, false);

		}

	} else

		spin_unlock(&inode->i_lock);

}



void

pnfs_put_lseg(struct pnfs_layout_segment *lseg)

{
@@ -410,15 +358,8 @@ pnfs_put_lseg(struct pnfs_layout_segment *lseg) 
		atomic_read(&lseg->pls_refcount),

		test_bit(NFS_LSEG_VALID, &lseg->pls_flags));



	/* Handle the case where refcount != 1 */

	if (atomic_add_unless(&lseg->pls_refcount, -1, 1))

		return;



	lo = lseg->pls_layout;

	inode = lo->plh_inode;

	/* Do we need a layoutreturn? */

	if (test_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags))

		pnfs_layoutreturn_before_put_lseg(lseg, lo, inode);



	if (atomic_dec_and_lock(&lseg->pls_refcount, &inode->i_lock)) {

		if (test_bit(NFS_LSEG_VALID, &lseg->pls_flags)) {
@@ -937,6 +878,17 @@ void pnfs_clear_layoutreturn_waitbit(struct pnfs_layout_hdr *lo) 
	rpc_wake_up(&NFS_SERVER(lo->plh_inode)->roc_rpcwaitq);

}



static bool

pnfs_prepare_layoutreturn(struct pnfs_layout_hdr *lo)

{

	if (test_and_set_bit(NFS_LAYOUT_RETURN, &lo->plh_flags))

		return false;

	lo->plh_return_iomode = 0;

	pnfs_get_layout_hdr(lo);

	clear_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE, &lo->plh_flags);

	return true;

}



static int

pnfs_send_layoutreturn(struct pnfs_layout_hdr *lo, const nfs4_stateid *stateid,

		       enum pnfs_iomode iomode, bool sync)
@@ -971,6 +923,48 @@ out: 
	return status;

}



/* Return true if layoutreturn is needed */

static bool

pnfs_layout_need_return(struct pnfs_layout_hdr *lo)

{

	struct pnfs_layout_segment *s;



	if (!test_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE, &lo->plh_flags))

		return false;



	/* Defer layoutreturn until all lsegs are done */

	list_for_each_entry(s, &lo->plh_segs, pls_list) {

		if (test_bit(NFS_LSEG_LAYOUTRETURN, &s->pls_flags))

			return false;

	}



	return true;

}



static void pnfs_layoutreturn_before_put_layout_hdr(struct pnfs_layout_hdr *lo)

{

	struct inode *inode= lo->plh_inode;



	if (!test_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE, &lo->plh_flags))

		return;

	spin_lock(&inode->i_lock);

	if (pnfs_layout_need_return(lo)) {

		nfs4_stateid stateid;

		enum pnfs_iomode iomode;

		bool send;



		nfs4_stateid_copy(&stateid, &lo->plh_stateid);

		iomode = lo->plh_return_iomode;

		send = pnfs_prepare_layoutreturn(lo);

		spin_unlock(&inode->i_lock);

		if (send) {

			/* Send an async layoutreturn so we dont deadlock */

			pnfs_send_layoutreturn(lo, &stateid, iomode, false);

		}

	} else

		spin_unlock(&inode->i_lock);

}



/*

 * Initiates a LAYOUTRETURN(FILE), and removes the pnfs_layout_hdr

 * when the layout segment list is empty.

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