2020-12-13 15:11:01

by chenlei0x

Subject: [PATCH] xfs: clean code for setting bma length in xfs_bmapi_write

From: Lei Chen <[email protected]>

xfs_bmapi_write may need alloc blocks when it encounters a hole
or delay extent. When setting bma.length, it does not need comparing
MAXEXTLEN and the length that the caller wants, because
xfs_bmapi_allocate will handle every thing properly for bma.length.

Signed-off-by: Lei Chen <[email protected]>
---
fs/xfs/libxfs/xfs_bmap.c | 13 +------------
1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index dcf56bc..e1b6ac6 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -4417,18 +4417,7 @@ struct xfs_iread_state {
bma.wasdel = wasdelay;
bma.offset = bno;
bma.flags = flags;
-
- /*
- * There's a 32/64 bit type mismatch between the
- * allocation length request (which can be 64 bits in
- * length) and the bma length request, which is
- * xfs_extlen_t and therefore 32 bits. Hence we have to
- * check for 32-bit overflows and handle them here.
- */
- if (len > (xfs_filblks_t)MAXEXTLEN)
- bma.length = MAXEXTLEN;
- else
- bma.length = len;
+ bma.length = len;

ASSERT(len > 0);
ASSERT(bma.length > 0);
--
1.8.3.1

2020-12-13 16:01:06

by Gao Xiang

Subject: Re: [PATCH] xfs: clean code for setting bma length in xfs_bmapi_write

On Sat, Dec 12, 2020 at 08:48:17PM +0800, [email protected] wrote:
> From: Lei Chen <[email protected]>
>
> xfs_bmapi_write may need alloc blocks when it encounters a hole
> or delay extent. When setting bma.length, it does not need comparing
> MAXEXTLEN and the length that the caller wants, because
> xfs_bmapi_allocate will handle every thing properly for bma.length.
>
> Signed-off-by: Lei Chen <[email protected]>
> ---
> fs/xfs/libxfs/xfs_bmap.c | 13 +------------
> 1 file changed, 1 insertion(+), 12 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index dcf56bc..e1b6ac6 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -4417,18 +4417,7 @@ struct xfs_iread_state {
> bma.wasdel = wasdelay;
> bma.offset = bno;
> bma.flags = flags;
> -
> - /*
> - * There's a 32/64 bit type mismatch between the
> - * allocation length request (which can be 64 bits in
> - * length) and the bma length request, which is
> - * xfs_extlen_t and therefore 32 bits. Hence we have to
> - * check for 32-bit overflows and handle them here.
> - */
> - if (len > (xfs_filblks_t)MAXEXTLEN)
> - bma.length = MAXEXTLEN;
> - else
> - bma.length = len;
> + bma.length = len;

After refering to the definition of struct xfs_bmalloca, so I think
bma.length is still a xfs_extlen_t ===> uint32_t, so I'm afraid the commit
a99ebf43f49f ("xfs: fix allocation length overflow in xfs_bmapi_write()")

and the reason for adding this is still valid for now?

Thanks,
Gao Xiang