2023-07-26 10:37:49

by Hao Xu

Subject: [PATCH 2/7] xfs: add nowait support for xfs_seek_iomap_begin()

From: Hao Xu <[email protected]>

To support nowait llseek(), IOMAP_NOWAIT semantics should be respected.
In xfs, xfs_seek_iomap_begin() is the only place which may be blocked
by ilock and extent loading. Let's turn it into trylock logic just like
what we've done in xfs_readdir().

Signed-off-by: Hao Xu <[email protected]>
---
fs/xfs/xfs_iomap.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 18c8f168b153..bbd7c6b27701 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -1294,7 +1294,9 @@ xfs_seek_iomap_begin(
if (xfs_is_shutdown(mp))
return -EIO;

- lockmode = xfs_ilock_data_map_shared(ip);
+ lockmode = xfs_ilock_data_map_shared_generic(ip, flags & IOMAP_NOWAIT);
+ if (!lockmode)
+ return -EAGAIN;
error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
if (error)
goto out_unlock;
--
2.25.1

2023-07-26 22:26:22

by Darrick J. Wong

Subject: Re: [PATCH 2/7] xfs: add nowait support for xfs_seek_iomap_begin()

On Thu, Jul 27, 2023 at 07:55:47AM +1000, Dave Chinner wrote:
> On Wed, Jul 26, 2023 at 06:25:58PM +0800, Hao Xu wrote:
> > From: Hao Xu <[email protected]>
> >
> > To support nowait llseek(), IOMAP_NOWAIT semantics should be respected.
> > In xfs, xfs_seek_iomap_begin() is the only place which may be blocked
> > by ilock and extent loading. Let's turn it into trylock logic just like
> > what we've done in xfs_readdir().
> >
> > Signed-off-by: Hao Xu <[email protected]>
> > ---
> > fs/xfs/xfs_iomap.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> > index 18c8f168b153..bbd7c6b27701 100644
> > --- a/fs/xfs/xfs_iomap.c
> > +++ b/fs/xfs/xfs_iomap.c
> > @@ -1294,7 +1294,9 @@ xfs_seek_iomap_begin(
> > if (xfs_is_shutdown(mp))
> > return -EIO;
> >
> > - lockmode = xfs_ilock_data_map_shared(ip);
> > + lockmode = xfs_ilock_data_map_shared_generic(ip, flags & IOMAP_NOWAIT);
>
> What does this magic XFS function I can't find anywhere in this
> patch set do?

It's in (iirc) the io_uring getdents patchset that wasn't cc'd to
linux-xfs and that I haven't looked at yet.

--D

> -Dave.
> --
> Dave Chinner
> [email protected]

2023-07-27 12:24:17

by Hao Xu

Subject: Re: [PATCH 2/7] xfs: add nowait support for xfs_seek_iomap_begin()

On 7/27/23 06:14, Darrick J. Wong wrote:
> On Thu, Jul 27, 2023 at 07:55:47AM +1000, Dave Chinner wrote:
>> On Wed, Jul 26, 2023 at 06:25:58PM +0800, Hao Xu wrote:
>>> From: Hao Xu <[email protected]>
>>>
>>> To support nowait llseek(), IOMAP_NOWAIT semantics should be respected.
>>> In xfs, xfs_seek_iomap_begin() is the only place which may be blocked
>>> by ilock and extent loading. Let's turn it into trylock logic just like
>>> what we've done in xfs_readdir().
>>>
>>> Signed-off-by: Hao Xu <[email protected]>
>>> ---
>>> fs/xfs/xfs_iomap.c | 4 +++-
>>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
>>> index 18c8f168b153..bbd7c6b27701 100644
>>> --- a/fs/xfs/xfs_iomap.c
>>> +++ b/fs/xfs/xfs_iomap.c
>>> @@ -1294,7 +1294,9 @@ xfs_seek_iomap_begin(
>>> if (xfs_is_shutdown(mp))
>>> return -EIO;
>>>
>>> - lockmode = xfs_ilock_data_map_shared(ip);
>>> + lockmode = xfs_ilock_data_map_shared_generic(ip, flags & IOMAP_NOWAIT);
>>
>> What does this magic XFS function I can't find anywhere in this
>> patch set do?

Sorry, forgot to say, It was xfs_ilock_for_readdir() in io_uring
getdents patchset, I changed the name since it is now used for
lseek as well.

>
> It's in (iirc) the io_uring getdents patchset that wasn't cc'd to
> linux-xfs and that I haven't looked at yet.
>

Hi Darrick, I forwarded the xfs related patch in that series. Forgot to
cc xfs list at the beginning. I'll make xfs list be Cc-ed when sending
next version. Sorry for inconvenience.

Regards,
Hao

> --D
>
>> -Dave.
>> --
>> Dave Chinner
>> [email protected]