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Commit a073dbff authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFSv4.1: Fix a race in pNFS layoutcommit 



We need to clear the NFS_LSEG_LAYOUTCOMMIT bits atomically with the
NFS_INO_LAYOUTCOMMIT bit, otherwise we may end up with situations
where the two are out of sync.
The first half of the problem is to ensure that pnfs_layoutcommit_inode
clears the NFS_LSEG_LAYOUTCOMMIT bit through pnfs_list_write_lseg.
We still need to keep the reference to those segments until the RPC call
is finished, so in order to make it clear _where_ those references come
from, we add a helper pnfs_list_write_lseg_done() that cleans up after
pnfs_list_write_lseg.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: default avatarBenny Halevy <bhalevy@tonian.com>
Cc: stable@vger.kernel.org
parent 4376c946

fs/nfs/nfs4proc.c

+0 −14
Original line number Diff line number Diff line
@@ -6416,22 +6416,8 @@ nfs4_layoutcommit_done(struct rpc_task *task, void *calldata) 
static void nfs4_layoutcommit_release(void *calldata)

{

	struct nfs4_layoutcommit_data *data = calldata;

	struct pnfs_layout_segment *lseg, *tmp;

	unsigned long *bitlock = &NFS_I(data->args.inode)->flags;



	pnfs_cleanup_layoutcommit(data);

	/* Matched by references in pnfs_set_layoutcommit */

	list_for_each_entry_safe(lseg, tmp, &data->lseg_list, pls_lc_list) {

		list_del_init(&lseg->pls_lc_list);

		if (test_and_clear_bit(NFS_LSEG_LAYOUTCOMMIT,

				       &lseg->pls_flags))

			pnfs_put_lseg(lseg);

	}



	clear_bit_unlock(NFS_INO_LAYOUTCOMMITTING, bitlock);

	smp_mb__after_clear_bit();

	wake_up_bit(bitlock, NFS_INO_LAYOUTCOMMITTING);



	put_rpccred(data->cred);

	kfree(data);

}

fs/nfs/pnfs.c

+18 −1
Original line number Diff line number Diff line
@@ -1746,11 +1746,27 @@ static void pnfs_list_write_lseg(struct inode *inode, struct list_head *listp) 


	list_for_each_entry(lseg, &NFS_I(inode)->layout->plh_segs, pls_list) {

		if (lseg->pls_range.iomode == IOMODE_RW &&

		    test_bit(NFS_LSEG_LAYOUTCOMMIT, &lseg->pls_flags))

		    test_and_clear_bit(NFS_LSEG_LAYOUTCOMMIT, &lseg->pls_flags))

			list_add(&lseg->pls_lc_list, listp);

	}

}



static void pnfs_list_write_lseg_done(struct inode *inode, struct list_head *listp)

{

	struct pnfs_layout_segment *lseg, *tmp;

	unsigned long *bitlock = &NFS_I(inode)->flags;



	/* Matched by references in pnfs_set_layoutcommit */

	list_for_each_entry_safe(lseg, tmp, listp, pls_lc_list) {

		list_del_init(&lseg->pls_lc_list);

		pnfs_put_lseg(lseg);

	}



	clear_bit_unlock(NFS_INO_LAYOUTCOMMITTING, bitlock);

	smp_mb__after_clear_bit();

	wake_up_bit(bitlock, NFS_INO_LAYOUTCOMMITTING);

}



void pnfs_set_lo_fail(struct pnfs_layout_segment *lseg)

{

	pnfs_layout_io_set_failed(lseg->pls_layout, lseg->pls_range.iomode);
@@ -1795,6 +1811,7 @@ void pnfs_cleanup_layoutcommit(struct nfs4_layoutcommit_data *data) 


	if (nfss->pnfs_curr_ld->cleanup_layoutcommit)

		nfss->pnfs_curr_ld->cleanup_layoutcommit(data);

	pnfs_list_write_lseg_done(data->args.inode, &data->lseg_list);

}



/*