* [PATCH] splice: allow direct splicing with chardevs
@ 2022-05-20 9:57 Jason A. Donenfeld
2022-05-20 14:34 ` Jens Axboe
0 siblings, 1 reply; 4+ messages in thread
From: Jason A. Donenfeld @ 2022-05-20 9:57 UTC (permalink / raw)
To: linux-kernel, viro; +Cc: Jason A. Donenfeld, Jens Axboe
The original direct splicing mechanism from Jens required the input to
be a regular file because it was avoiding the special socket case. It
also recognized blkdevs as being close enough to a regular file. But it
forgot about chardevs, which behave the same way and work fine here.
This commit adds the missing S_ISCHR condition so that chardevs such as
/dev/urandom can be directly spliced without strangely returning
-EINVAL.
Cc: Jens Axboe <axboe@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Fixes: b92ce5589374 ("[PATCH] splice: add direct fd <-> fd splicing support")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
fs/splice.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/splice.c b/fs/splice.c
index 047b79db8eb5..7e673b1786fb 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -824,7 +824,7 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
* piped splicing for that!
*/
i_mode = file_inode(in)->i_mode;
- if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
+ if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISCHR(i_mode)))
return -EINVAL;
/*
--
2.35.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] splice: allow direct splicing with chardevs
2022-05-20 9:57 [PATCH] splice: allow direct splicing with chardevs Jason A. Donenfeld
@ 2022-05-20 14:34 ` Jens Axboe
2022-05-26 21:19 ` Jason A. Donenfeld
0 siblings, 1 reply; 4+ messages in thread
From: Jens Axboe @ 2022-05-20 14:34 UTC (permalink / raw)
To: Jason A. Donenfeld, linux-kernel, viro; +Cc: Jens Axboe
On 5/20/22 3:57 AM, Jason A. Donenfeld wrote:
> The original direct splicing mechanism from Jens required the input to
> be a regular file because it was avoiding the special socket case. It
> also recognized blkdevs as being close enough to a regular file. But it
> forgot about chardevs, which behave the same way and work fine here.
>
> This commit adds the missing S_ISCHR condition so that chardevs such as
> /dev/urandom can be directly spliced without strangely returning
> -EINVAL.
Should be fine to turn this on for char devices:
Reviewed-by: Jens Axboe <axboe@kernel.dk>
--
Jens Axboe
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] splice: allow direct splicing with chardevs
2022-05-20 14:34 ` Jens Axboe
@ 2022-05-26 21:19 ` Jason A. Donenfeld
2022-06-08 12:49 ` Jason A. Donenfeld
0 siblings, 1 reply; 4+ messages in thread
From: Jason A. Donenfeld @ 2022-05-26 21:19 UTC (permalink / raw)
To: viro; +Cc: linux-kernel, Jens Axboe
Hey Al,
On 5/20/22, Jens Axboe <axboe@kernel.dk> wrote:
> On 5/20/22 3:57 AM, Jason A. Donenfeld wrote:
>> The original direct splicing mechanism from Jens required the input to
>> be a regular file because it was avoiding the special socket case. It
>> also recognized blkdevs as being close enough to a regular file. But it
>> forgot about chardevs, which behave the same way and work fine here.
>>
>> This commit adds the missing S_ISCHR condition so that chardevs such as
>> /dev/urandom can be directly spliced without strangely returning
>> -EINVAL.
>
> Should be fine to turn this on for char devices:
>
> Reviewed-by: Jens Axboe <axboe@kernel.dk>
>
Was wondering if this would make 5.19. That'd be nice, as it's the
release in which we switch to read_iter().
Jason
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] splice: allow direct splicing with chardevs
2022-05-26 21:19 ` Jason A. Donenfeld
@ 2022-06-08 12:49 ` Jason A. Donenfeld
0 siblings, 0 replies; 4+ messages in thread
From: Jason A. Donenfeld @ 2022-06-08 12:49 UTC (permalink / raw)
To: viro; +Cc: linux-kernel, Jens Axboe
Hey again,
On Thu, May 26, 2022 at 11:19:46PM +0200, Jason A. Donenfeld wrote:
> Hey Al,
>
> On 5/20/22, Jens Axboe <axboe@kernel.dk> wrote:
> > On 5/20/22 3:57 AM, Jason A. Donenfeld wrote:
> >> The original direct splicing mechanism from Jens required the input to
> >> be a regular file because it was avoiding the special socket case. It
> >> also recognized blkdevs as being close enough to a regular file. But it
> >> forgot about chardevs, which behave the same way and work fine here.
> >>
> >> This commit adds the missing S_ISCHR condition so that chardevs such as
> >> /dev/urandom can be directly spliced without strangely returning
> >> -EINVAL.
> >
> > Should be fine to turn this on for char devices:
> >
> > Reviewed-by: Jens Axboe <axboe@kernel.dk>
> >
>
> Was wondering if this would make 5.19. That'd be nice, as it's the
> release in which we switch to read_iter().
Just thought I should ping once more on this. Should probably be queued
up somewhat soon for 5.19 if it's to make 5.19, which I would really
appreciate.
Jason
^ permalink raw reply [flat|nested] 4+ messages in thread
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2022-05-20 9:57 [PATCH] splice: allow direct splicing with chardevs Jason A. Donenfeld
2022-05-20 14:34 ` Jens Axboe
2022-05-26 21:19 ` Jason A. Donenfeld
2022-06-08 12:49 ` Jason A. Donenfeld
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