Re: [PATCH 3/7] btrfs: use i_size_read() instead of open code

2017-11-15 Thread David Sterba 
On Tue, Nov 07, 2017 at 07:44:59AM +0800, Anand Jain wrote:
> 
> 
> On 11/07/2017 12:52 AM, David Sterba wrote:
> > On Mon, Nov 06, 2017 at 04:36:14PM +0800, Anand Jain wrote:
> >> As i_size_read() takes care of 32bit smp or preempt cases as well.
> > 
> > Can bdev->bd_inode->i_size change so that we need to use the
> > i_size_read()? My answer is 'no'.
> 
>   Hm. Right I was looking at it only from the theoretical point of view.
> 
>   And I presume you mean to say disk resize at the block layer is not
>   really a practically achievable concern.

There are some safety checks, at least if there are bios in flight on
the partition when it's mounted.
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Re: [PATCH 3/7] btrfs: use i_size_read() instead of open code

2017-11-06 Thread Anand Jain 



On 11/07/2017 12:52 AM, David Sterba wrote:

On Mon, Nov 06, 2017 at 04:36:14PM +0800, Anand Jain wrote:

As i_size_read() takes care of 32bit smp or preempt cases as well.


Can bdev->bd_inode->i_size change so that we need to use the
i_size_read()? My answer is 'no'.


 Hm. Right I was looking at it only from the theoretical point of view.

 And I presume you mean to say disk resize at the block layer is not
 really a practically achievable concern.

Thanks, Anand
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Re: [PATCH 3/7] btrfs: use i_size_read() instead of open code

2017-11-06 Thread David Sterba 
On Mon, Nov 06, 2017 at 04:36:14PM +0800, Anand Jain wrote:
> As i_size_read() takes care of 32bit smp or preempt cases as well.

Can bdev->bd_inode->i_size change so that we need to use the
i_size_read()? My answer is 'no'. You haven't provided any reasoning
why it should be otherwise.
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[PATCH 3/7] btrfs: use i_size_read() instead of open code

2017-11-06 Thread Anand Jain 
As i_size_read() takes care of 32bit smp or preempt cases as well.

Signed-off-by: Anand Jain 
---
 fs/btrfs/ioctl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index b0465020972a..86e7f5abd740 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1532,7 +1532,7 @@ static noinline int btrfs_ioctl_resize(struct file *file,
}
 
if (!new_size)
-   new_size = device->bdev->bd_inode->i_size;
+   new_size = i_size_read(device->bdev->bd_inode);
 
old_size = btrfs_device_get_total_bytes(device);
 
@@ -1554,7 +1554,7 @@ static noinline int btrfs_ioctl_resize(struct file *file,
ret = -EINVAL;
goto out_mutex;
}
-   if (new_size > device->bdev->bd_inode->i_size) {
+   if (new_size > i_size_read(device->bdev->bd_inode)) {
ret = -EFBIG;
goto out_mutex;
}
-- 
2.13.1

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