fuse_direct_io() expects this to return either 0 or a negative
error code, but on success it may return a positive value.
fuse_direct_io() may return this same value when the subsequent
I/O operation doesn't transfer any data, which means that it will
return a positive value when no bytes were transferred. This is
obviously problematic.
Fix fuse_get_user_pages() to return 0 on success. This will in
turn make it so that fuse_direct_io() returns 0 if no bytes are
transferred.
Fixes: 742f992708df ("fuse: return patrial success from fuse_direct_io()")
Signed-off-by: Seth Forshee <[email protected]>
---
fs/fuse/file.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index b5c616c5ec98..78af5c0996b8 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1295,7 +1295,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
*nbytesp = nbytes;
- return ret;
+ return ret < 0 ? ret : 0;
}
static inline int fuse_iter_npages(const struct iov_iter *ii_p)
--
1.9.1
Hi Seth,
On 04/19/2016 03:43 PM, Seth Forshee wrote:
> fuse_direct_io() expects this to return either 0 or a negative
> error code, but on success it may return a positive value.
> fuse_direct_io() may return this same value when the subsequent
> I/O operation doesn't transfer any data, which means that it will
> return a positive value when no bytes were transferred. This is
> obviously problematic.
>
> Fix fuse_get_user_pages() to return 0 on success. This will in
> turn make it so that fuse_direct_io() returns 0 if no bytes are
> transferred.
>
> Fixes: 742f992708df ("fuse: return patrial success from fuse_direct_io()")
> Signed-off-by: Seth Forshee <[email protected]>
> ---
> fs/fuse/file.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index b5c616c5ec98..78af5c0996b8 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -1295,7 +1295,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
>
> *nbytesp = nbytes;
>
> - return ret;
> + return ret < 0 ? ret : 0;
> }
>
> static inline int fuse_iter_npages(const struct iov_iter *ii_p)
I have already sent a patch to the list that does exactly the same thing :)
https://sourceforge.net/p/fuse/mailman/message/34966327/
Thanks,
Ashish
On Tue, Apr 19, 2016 at 03:57:52PM -0700, Ashish Samant wrote:
> Hi Seth,
> On 04/19/2016 03:43 PM, Seth Forshee wrote:
> >fuse_direct_io() expects this to return either 0 or a negative
> >error code, but on success it may return a positive value.
> >fuse_direct_io() may return this same value when the subsequent
> >I/O operation doesn't transfer any data, which means that it will
> >return a positive value when no bytes were transferred. This is
> >obviously problematic.
> >
> >Fix fuse_get_user_pages() to return 0 on success. This will in
> >turn make it so that fuse_direct_io() returns 0 if no bytes are
> >transferred.
> >
> >Fixes: 742f992708df ("fuse: return patrial success from fuse_direct_io()")
> >Signed-off-by: Seth Forshee <[email protected]>
> >---
> > fs/fuse/file.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> >diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> >index b5c616c5ec98..78af5c0996b8 100644
> >--- a/fs/fuse/file.c
> >+++ b/fs/fuse/file.c
> >@@ -1295,7 +1295,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
> > *nbytesp = nbytes;
> >- return ret;
> >+ return ret < 0 ? ret : 0;
> > }
> > static inline int fuse_iter_npages(const struct iov_iter *ii_p)
>
>
> I have already sent a patch to the list that does exactly the same thing :)
>
> https://sourceforge.net/p/fuse/mailman/message/34966327/
Oops, should have checked the list first I guess :-)
But that's from several weeks ago, and it's still not applied? This is
causing big problems for lxcfs on 4.6-rc kernels, so it's definitely a
regression and needs to get fixed.
Thanks,
Seth
On Wed, Apr 20, 2016 at 5:43 PM, Seth Forshee
<[email protected]> wrote:
> On Tue, Apr 19, 2016 at 03:57:52PM -0700, Ashish Samant wrote:
>> Hi Seth,
>> On 04/19/2016 03:43 PM, Seth Forshee wrote:
>> >fuse_direct_io() expects this to return either 0 or a negative
>> >error code, but on success it may return a positive value.
>> >fuse_direct_io() may return this same value when the subsequent
>> >I/O operation doesn't transfer any data, which means that it will
>> >return a positive value when no bytes were transferred. This is
>> >obviously problematic.
>> >
>> >Fix fuse_get_user_pages() to return 0 on success. This will in
>> >turn make it so that fuse_direct_io() returns 0 if no bytes are
>> >transferred.
>> >
>> >Fixes: 742f992708df ("fuse: return patrial success from fuse_direct_io()")
>> >Signed-off-by: Seth Forshee <[email protected]>
>> >---
>> > fs/fuse/file.c | 2 +-
>> > 1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> >diff --git a/fs/fuse/file.c b/fs/fuse/file.c
>> >index b5c616c5ec98..78af5c0996b8 100644
>> >--- a/fs/fuse/file.c
>> >+++ b/fs/fuse/file.c
>> >@@ -1295,7 +1295,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
>> > *nbytesp = nbytes;
>> >- return ret;
>> >+ return ret < 0 ? ret : 0;
>> > }
>> > static inline int fuse_iter_npages(const struct iov_iter *ii_p)
>>
>>
>> I have already sent a patch to the list that does exactly the same thing :)
>>
>> https://sourceforge.net/p/fuse/mailman/message/34966327/
>
> Oops, should have checked the list first I guess :-)
>
> But that's from several weeks ago, and it's still not applied? This is
> causing big problems for lxcfs on 4.6-rc kernels, so it's definitely a
> regression and needs to get fixed.
Applied, thanks.
Miklos