From: Dave Chinner <dchinner@xxxxxxxxxx>
We need the zero block tracking structure allocation to succeed.
Silently failing and potentially allowing data corruption is not an
option. Add a mempool to ensure this allocation will always succeed.
Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
fs/direct-io.c | 14 +++++++++++---
1 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 368abec..dfc5d9a 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -161,12 +161,22 @@ struct dio_zero_block_head {
static struct dio_zero_block_head dio_zero_blocks[DIO_ZERO_BLOCK_NR];
#define to_dio_zero_head(zb) (&dio_zero_blocks[zb % DIO_ZERO_BLOCK_NR])
+/* a small mempool just to guarantee progress. */
+#define DIO_ZERO_BLOCK_ENTRIES 2
+static mempool_t *dio_zero_block_pool;
+
static int __init
dio_init_zero_block(void)
{
int i;
+ dio_zero_block_pool = mempool_create_kmalloc_pool(
+ DIO_ZERO_BLOCK_ENTRIES,
+ sizeof(struct dio_zero_block));
+ if (!dio_zero_block_pool)
+ panic("dio: can't create zero block pool");
+
for (i = 0; i < DIO_ZERO_BLOCK_NR; i++) {
spin_lock_init(&dio_zero_blocks[i].lock);
INIT_LIST_HEAD(&dio_zero_blocks[i].list);
@@ -184,9 +194,7 @@ dio_start_zero_block(struct dio *dio, sector_t zero_block)
struct dio_zero_block_head *zbh = to_dio_zero_head(zero_block);
struct dio_zero_block *zb;
- zb = kmalloc(sizeof(*zb), GFP_NOIO);
- if (!zb)
- return;
+ zb = mempool_alloc(dio_zero_block_pool, GFP_NOIO);
INIT_LIST_HEAD(&zb->dio_list);
init_waitqueue_head(&zb->wq);
zb->zero_block = zero_block;
--
1.7.1
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