Messages in this thread | | | Date | Wed, 23 Nov 2022 18:57:41 +0100 | Subject | Re: Kernel 6.0.5 breaks virtual machines that boot from nfs mounted qcow2 images | From | Anders Blomdell <> |
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On 2022-11-23 18:51, Chuck Lever III wrote: > >> On Nov 23, 2022, at 12:49 PM, Benjamin Coddington <bcodding@redhat.com> wrote: >> >> On 23 Nov 2022, at 5:08, Anders Blomdell wrote: >> >>> Our problems turned out to be a fallout of Al Viros's splice rework, where nfsd reads with non-zero offsets and not ending >>> on a page boundary failed to remap the last page. I belive that this is a decent fix for that problem (tested on v6.1-rc6, >>> 6.0.7 and 6.0.9) >>> >>> ---- a/fs/nfsd/vfs.c >>> +++ b/fs/nfsd/vfs.c >>> @@ -873,7 +873,7 @@ nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf, >>> unsigned offset = buf->offset; >>> page += offset / PAGE_SIZE; >>> - for (int i = sd->len; i > 0; i -= PAGE_SIZE) >>> + for (int i = sd->len + offset % PAGE_SIZE; i > 0; i -= PAGE_SIZE) >>> svc_rqst_replace_page(rqstp, page++); >>> if (rqstp->rq_res.page_len == 0) // first call >>> rqstp->rq_res.page_base = offset % PAGE_SIZE; >> >> >> Does anyone have insight into how we could possibly have caught this in testing? > > Was also wondering this. I had though fstests (via fsx) would have exercised > this usage scenario. My guess is that one has to look very hard at qcow2 handling in qemu...
/Anders
-- Anders Blomdell Email: anders.blomdell@control.lth.se Department of Automatic Control Lund University Phone: +46 46 222 4625 P.O. Box 118 SE-221 00 Lund, Sweden
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