Re: [PATCH v2] xfs: check the remaining length of extent after roundup

From: Darrick J. Wong
Date: Thu Nov 07 2024 - 15:05:47 EST


On Thu, Nov 07, 2024 at 04:40:44PM +0800, Jinliang Zheng wrote:
> In xfs_alloc_compute_diff(), ensure that the remaining length of extent
> still meets the wantlen requirements after newbno1 is rounded.

What problem are you observing?

--D

> Signed-off-by: Jinliang Zheng <alexjlzheng@xxxxxxxxxxx>
> ---
> Changelog:
>
> V2: Fix the error logic
>
> V1: https://lore.kernel.org/linux-xfs/20241107070300.13535-1-alexjlzheng@xxxxxxxxxxx/#R
> ---
> fs/xfs/libxfs/xfs_alloc.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index 22bdbb3e9980..1d4cc75b7318 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -393,7 +393,8 @@ xfs_alloc_compute_diff(
> * grows in the short term.
> */
> if (freebno >= wantbno || (userdata && freeend < wantend)) {
> - if ((newbno1 = roundup(freebno, alignment)) >= freeend)
> + newbno1 = roundup(freebno, alignment);
> + if (newbno1 >= freeend || newbno1 > freeend - wantlen)
> newbno1 = NULLAGBLOCK;
> } else if (freeend >= wantend && alignment > 1) {
> newbno1 = roundup(wantbno, alignment);
> @@ -414,6 +415,8 @@ xfs_alloc_compute_diff(
> newbno1 = newbno2;
> } else if (newbno2 != NULLAGBLOCK)
> newbno1 = newbno2;
> + if (newbno1 > freeend - wantlen)
> + newbno1 = NULLAGBLOCK;
> } else if (freeend >= wantend) {
> newbno1 = wantbno;
> } else if (alignment > 1) {
> --
> 2.41.1
>
>