NFSv4/pNFS: Clear NFS_INO_LAYOUTCOMMIT in pnfs_mark_layout_stateid_invalid

Fixes a crash when layout is null during this call stack:

write_inode
    -> nfs4_write_inode
        -> pnfs_layoutcommit_inode

pnfs_set_layoutcommit relies on the lseg refcount to keep the layout
around. Need to clear NFS_INO_LAYOUTCOMMIT otherwise we might attempt
to reference a null layout.

Fixes: fe1cf94 ("pNFS: Clear all layout segment state in pnfs_mark_layout_stateid_invalid")
Signed-off-by: Jonathan Curley <jcurley@purestorage.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

Author: Jonathan Curley

fs/nfs/pnfs.c

@@ -464,6 +464,7 @@ pnfs_mark_layout_stateid_invalid(struct pnfs_layout_hdr *lo,
 	struct pnfs_layout_segment *lseg, *next;
 
 	set_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags);
+	clear_bit(NFS_INO_LAYOUTCOMMIT, &NFS_I(lo->plh_inode)->flags);
 	list_for_each_entry_safe(lseg, next, &lo->plh_segs, pls_list)
 		pnfs_clear_lseg_state(lseg, lseg_list);
 	pnfs_clear_layoutreturn_info(lo);