Re: About the try to remove cross-release feature entirely by Ingo
On Fri, Jan 05, 2018 at 11:49:41AM -0500, bfields wrote: > On Mon, Jan 01, 2018 at 02:18:55AM -0800, Matthew Wilcox wrote: > > On Sat, Dec 30, 2017 at 06:00:57PM -0500, Theodore Ts'o wrote: > > > On Sat, Dec 30, 2017 at 05:40:28PM -0500, Theodore Ts'o wrote: > > > > On Sat, Dec 30, 2017 at 12:44:17PM -0800, Matthew Wilcox wrote: > > > > > > > > > > I'm not sure I agree with this part. What if we add a new TCP lock > > > > > class > > > > > for connections which are used for filesystems/network block > > > > > devices/...? > > > > > Yes, it'll be up to each user to set the lockdep classification > > > > > correctly, > > > > > but that's a relatively small number of places to add annotations, > > > > > and I don't see why it wouldn't work. > > > > > > > > I was exagerrating a bit for effect, I admit. (but only a bit). > > > > I feel like there's been rather too much of that recently. Can we stick > > to facts as far as possible, please? > > > > > > It can probably be for all TCP connections that are used by kernel > > > > code (as opposed to userspace-only TCP connections). But it would > > > > probably have to be each and every device-mapper instance, each and > > > > every block device, each and every mounted file system, each and every > > > > bdi object, etc. > > > > > > Clarification: all TCP connections that are used by kernel code would > > > need to be in their own separate lock class. All TCP connections used > > > only by userspace could be in their own shared lock class. You can't > > > use a one lock class for all kernel-used TCP connections, because of > > > the Network Block Device mounted on a local file system which is then > > > exported via NFS and squirted out yet another TCP connection problem. > > > > So the false positive you're concerned about is write-comes-in-over-NFS > > (with socket lock held), NFS sends a write request to local filesystem, > > I'm confused, what lock does Ted think the NFS server is holding over > NFS processing? Sorry, I meant "over RPC processing". I'll confess to no understanding of socket locking. The server RPC code doesn't take any itself except in a couple places on setup and tear down of a connection. We wouldn't actually want any exclusive per-connection lock held across RPC processing because we want to be able to handle multiple concurrent RPCs per connection. We do need a little locking just to make sure multiple server threads replying to the same client don't accidentally corrupt their replies by interleaving. But even there we're using our own lock, held only while transmitting the reply (after all the work's done and reply encoded). --b.
Re: About the try to remove cross-release feature entirely by Ingo
On Mon, Jan 01, 2018 at 02:18:55AM -0800, Matthew Wilcox wrote: > On Sat, Dec 30, 2017 at 06:00:57PM -0500, Theodore Ts'o wrote: > > On Sat, Dec 30, 2017 at 05:40:28PM -0500, Theodore Ts'o wrote: > > > On Sat, Dec 30, 2017 at 12:44:17PM -0800, Matthew Wilcox wrote: > > > > > > > > I'm not sure I agree with this part. What if we add a new TCP lock > > > > class > > > > for connections which are used for filesystems/network block > > > > devices/...? > > > > Yes, it'll be up to each user to set the lockdep classification > > > > correctly, > > > > but that's a relatively small number of places to add annotations, > > > > and I don't see why it wouldn't work. > > > > > > I was exagerrating a bit for effect, I admit. (but only a bit). > > I feel like there's been rather too much of that recently. Can we stick > to facts as far as possible, please? > > > > It can probably be for all TCP connections that are used by kernel > > > code (as opposed to userspace-only TCP connections). But it would > > > probably have to be each and every device-mapper instance, each and > > > every block device, each and every mounted file system, each and every > > > bdi object, etc. > > > > Clarification: all TCP connections that are used by kernel code would > > need to be in their own separate lock class. All TCP connections used > > only by userspace could be in their own shared lock class. You can't > > use a one lock class for all kernel-used TCP connections, because of > > the Network Block Device mounted on a local file system which is then > > exported via NFS and squirted out yet another TCP connection problem. > > So the false positive you're concerned about is write-comes-in-over-NFS > (with socket lock held), NFS sends a write request to local filesystem, I'm confused, what lock does Ted think the NFS server is holding over NFS processing? --b.
Re: [PATCH v2 6/6] nfsd: Check queue type before submitting a SCSI request
Feel free to add
Acked-by: J. Bruce Fields
if you need it.--b.
On Wed, May 31, 2017 at 02:43:50PM -0700, Bart Van Assche wrote:
> Since using scsi_req() is only allowed against request queues for
> which struct scsi_request is the first member of their private
> request data, refuse to submit SCSI commands against a queue for
> which this is not the case.
>
> References: commit 82ed4db499b8 ("block: split scsi_request out of struct
> request")
> Signed-off-by: Bart Van Assche
> Reviewed-by: Hannes Reinecke
> Reviewed-by: Christoph Hellwig
> Cc: J. Bruce Fields
> Cc: Jeff Layton
> Cc: Omar Sandoval
> Cc: linux-...@vger.kernel.org
> ---
> fs/nfsd/blocklayout.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
> index fb5213afc854..47ed19c53f2e 100644
> --- a/fs/nfsd/blocklayout.c
> +++ b/fs/nfsd/blocklayout.c
> @@ -219,6 +219,9 @@ static int nfsd4_scsi_identify_device(struct block_device
> *bdev,
> u8 *buf, *d, type, assoc;
> int error;
>
> + if (WARN_ON_ONCE(!blk_queue_scsi_passthrough(q)))
> + return -EINVAL;
> +
> buf = kzalloc(bufflen, GFP_KERNEL);
> if (!buf)
> return -ENOMEM;
> --
> 2.12.2
Re: [PATCH 06/19] nfsd: Check private request size before submitting a SCSI request
On Thu, May 25, 2017 at 11:43:14AM -0700, Bart Van Assche wrote:
> Since using scsi_req() is only allowed against request queues for
> which struct scsi_request is the first member of their private
> request data, refuse to submit SCSI commands against a queue for
> which this is not the case.
Is it possible we could catch this earlier and avoid giving out the
layout in the first place?
--b.
>
> References: commit 82ed4db499b8 ("block: split scsi_request out of struct
> request")
> Signed-off-by: Bart Van Assche
> Reviewed-by: Hannes Reinecke
> Cc: J. Bruce Fields
> Cc: Jeff Layton
> Cc: Jens Axboe
> Cc: Christoph Hellwig
> Cc: Omar Sandoval
> Cc: linux-...@vger.kernel.org
> Cc: linux-block@vger.kernel.org
> ---
> fs/nfsd/blocklayout.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
> index fb5213afc854..38e14cf7e74a 100644
> --- a/fs/nfsd/blocklayout.c
> +++ b/fs/nfsd/blocklayout.c
> @@ -219,6 +219,9 @@ static int nfsd4_scsi_identify_device(struct block_device
> *bdev,
> u8 *buf, *d, type, assoc;
> int error;
>
> + if (WARN_ON_ONCE(!blk_queue_scsi_pdu(q)))
> + return -EINVAL;
> +
> buf = kzalloc(bufflen, GFP_KERNEL);
> if (!buf)
> return -ENOMEM;
> --
> 2.12.2
Re: [PATCH 05/18] nfsd: Check private request size before submitting a SCSI request
ACK as far as I'm concerned.--b.
On Fri, May 19, 2017 at 11:30:03AM -0700, Bart Van Assche wrote:
> Since using scsi_req() is only allowed against request queues for which
> struct scsi_request is the first member of their private request
> data, refuse to register block layer queues for which the private
> data is smaller than struct scsi_request.
>
> References: commit 82ed4db499b8 ("block: split scsi_request out of struct
> request")
> Signed-off-by: Bart Van Assche
> Cc: J. Bruce Fields
> Cc: Jeff Layton
> Cc: Jens Axboe
> Cc: Christoph Hellwig
> Cc: Omar Sandoval
> Cc: Hannes Reinecke
> Cc: linux-...@vger.kernel.org
> Cc: linux-block@vger.kernel.org
> ---
> fs/nfsd/blocklayout.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
> index fb5213afc854..90d1df31491b 100644
> --- a/fs/nfsd/blocklayout.c
> +++ b/fs/nfsd/blocklayout.c
> @@ -219,6 +219,9 @@ static int nfsd4_scsi_identify_device(struct block_device
> *bdev,
> u8 *buf, *d, type, assoc;
> int error;
>
> + if (WARN_ON_ONCE(blk_queue_cmd_size(q) < sizeof(struct scsi_request)))
> + return -EINVAL;
> +
> buf = kzalloc(bufflen, GFP_KERNEL);
> if (!buf)
> return -ENOMEM;
> --
> 2.12.2
