* [PATCH] xfs: ensure f_bfree returned by statfs() is non-negative
@ 2020-05-11 2:45 Zheng Bin
2020-05-12 11:54 ` Brian Foster
0 siblings, 1 reply; 2+ messages in thread
From: Zheng Bin @ 2020-05-11 2:45 UTC (permalink / raw)
To: bfoster, dchinner, sandeen, darrick.wong, linux-xfs; +Cc: yi.zhang, zhengbin13
Construct an img like this:
dd if=/dev/zero of=xfs.img bs=1M count=20
mkfs.xfs -d agcount=1 xfs.img
xfs_db -x xfs.img
sb 0
write fdblocks 0
agf 0
write freeblks 0
write longest 0
quit
mount it, df -h /mnt(xfs mount point), will show this:
Filesystem Size Used Avail Use% Mounted on
/dev/loop0 17M -64Z -32K 100% /mnt
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zheng Bin <zhengbin13@huawei.com>
---
fs/xfs/xfs_super.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index e80bd2c4c279..aae469f73efe 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -807,7 +807,8 @@ xfs_fs_statfs(
statp->f_blocks = sbp->sb_dblocks - lsize;
spin_unlock(&mp->m_sb_lock);
- statp->f_bfree = fdblocks - mp->m_alloc_set_aside;
+ /* make sure statp->f_bfree does not underflow */
+ statp->f_bfree = max_t(int64_t, fdblocks - mp->m_alloc_set_aside, 0);
statp->f_bavail = statp->f_bfree;
fakeinos = XFS_FSB_TO_INO(mp, statp->f_bfree);
--
2.26.0.106.g9fadedd
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] xfs: ensure f_bfree returned by statfs() is non-negative
2020-05-11 2:45 [PATCH] xfs: ensure f_bfree returned by statfs() is non-negative Zheng Bin
@ 2020-05-12 11:54 ` Brian Foster
0 siblings, 0 replies; 2+ messages in thread
From: Brian Foster @ 2020-05-12 11:54 UTC (permalink / raw)
To: Zheng Bin; +Cc: dchinner, sandeen, darrick.wong, linux-xfs, yi.zhang
On Mon, May 11, 2020 at 10:45:24AM +0800, Zheng Bin wrote:
> Construct an img like this:
>
> dd if=/dev/zero of=xfs.img bs=1M count=20
> mkfs.xfs -d agcount=1 xfs.img
> xfs_db -x xfs.img
> sb 0
> write fdblocks 0
> agf 0
> write freeblks 0
> write longest 0
> quit
>
> mount it, df -h /mnt(xfs mount point), will show this:
> Filesystem Size Used Avail Use% Mounted on
> /dev/loop0 17M -64Z -32K 100% /mnt
>
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Zheng Bin <zhengbin13@huawei.com>
> ---
Seems reasonable to me:
Reviewed-by: Brian Foster <bfoster@redhat.com>
> fs/xfs/xfs_super.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index e80bd2c4c279..aae469f73efe 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -807,7 +807,8 @@ xfs_fs_statfs(
> statp->f_blocks = sbp->sb_dblocks - lsize;
> spin_unlock(&mp->m_sb_lock);
>
> - statp->f_bfree = fdblocks - mp->m_alloc_set_aside;
> + /* make sure statp->f_bfree does not underflow */
> + statp->f_bfree = max_t(int64_t, fdblocks - mp->m_alloc_set_aside, 0);
> statp->f_bavail = statp->f_bfree;
>
> fakeinos = XFS_FSB_TO_INO(mp, statp->f_bfree);
> --
> 2.26.0.106.g9fadedd
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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