The first write after file create fails to take the direct IO
(Peer-to-Peer) path and falls back to slower software copy. The function
get_more_block() sets 'create' to 0 after comparing 'unsigned long
fs_startblk = 0' with 'long long (i_size_read(dio->inode) - 1) >>
i_blkbits = 0xfffffffffffff'.
v2: Instead of casting to loff_t check explicitly if i_size > 0
v3: Use cached dio->i_size instead of i_size_read() which isn't cheap on
32-bit SMP
Signed-off-by: Harish Kasiviswanathan <Harish.Kasiviswanathan@xxxxxxx>
---
fs/direct-io.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 3aafb33..1c33830 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -686,9 +686,8 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio,
* buffer head.
*/
create = dio->op == REQ_OP_WRITE;
- if (dio->flags & DIO_SKIP_HOLES) {
- if (fs_startblk <= ((i_size_read(dio->inode) - 1) >>
- i_blkbits))
+ if (dio->flags & DIO_SKIP_HOLES && dio->i_size) {
+ if (fs_startblk <= ((dio->i_size - 1) >> i_blkbits))
create = 0;
}
--
2.7.4
