[PATCH] NFS: check the return value of mempool_alloc()

[xkernel . wang]

From: Xiaoke Wang <xkernel.wang@xxxxxxxxxxx>

The check was first removed in 518662e ("NFS: fix usage of mempools.")
as the passed GFP flags is `GFP_NOIO`.
While now the flag is changed to `GFP_KERNEL` by 2b17d72 ("NFS: Clean
up writeback code"), so it is better to check it.

Signed-off-by: Xiaoke Wang <xkernel.wang@xxxxxxxxxxx>
---
 fs/nfs/write.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index eae9bf1..831fad9 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -106,8 +106,10 @@ static struct nfs_pgio_header *nfs_writehdr_alloc(void)
 {
 	struct nfs_pgio_header *p = mempool_alloc(nfs_wdata_mempool, GFP_KERNEL);
 
-	memset(p, 0, sizeof(*p));
-	p->rw_mode = FMODE_WRITE;
+	if (p) {
+		memset(p, 0, sizeof(*p));
+		p->rw_mode = FMODE_WRITE;
+	}
 	return p;
 }
 
--