Commit fbf4bcc9 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Fix an ABBA spinlock issue in pnfs_update_layout() 



We need to drop the inode spinlock while calling nfs4_select_rw_stateid(),
since nfs4_copy_delegation_stateid() could take the delegation lock.
Note that it is safe to do this, since all other calls to
pnfs_update_layout() for that inode will find themselves blocked by
the lock we hold on NFS_LAYOUT_FIRST_LAYOUTGET.

Fixes: fc51b1cf ("NFS: Beware when dereferencing the delegation cred")
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent 8f3d9f35

fs/nfs/pnfs.c

+2 −1
Original line number Diff line number Diff line
@@ -2023,6 +2023,7 @@ pnfs_update_layout(struct inode *ino, 
			goto lookup_again;

		}



		spin_unlock(&ino->i_lock);

		first = true;

		status = nfs4_select_rw_stateid(ctx->state,

					iomode == IOMODE_RW ? FMODE_WRITE : FMODE_READ,
@@ -2032,12 +2033,12 @@ pnfs_update_layout(struct inode *ino, 
			trace_pnfs_update_layout(ino, pos, count,

					iomode, lo, lseg,

					PNFS_UPDATE_LAYOUT_INVALID_OPEN);

			spin_unlock(&ino->i_lock);

			nfs4_schedule_stateid_recovery(server, ctx->state);

			pnfs_clear_first_layoutget(lo);

			pnfs_put_layout_hdr(lo);

			goto lookup_again;

		}

		spin_lock(&ino->i_lock);

	} else {

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

	}