From: Mike Snitzer <snitzer@kernel.org>
To: Trond Myklebust <trondmy@kernel.org>, Anna Schumaker <anna@kernel.org>
Cc: linux-nfs@vger.kernel.org
Subject: [PATCH] NFS/localio: fix nfs_local_dio_misaligned tracepoint
Date: Wed, 8 Jul 2026 17:36:10 -0400 [thread overview]
Message-ID: <20260708213610.19001-1-snitzer@kernel.org> (raw)
The intended focus of nfs_local_iters_setup_dio()'s call to
trace_nfs_local_dio_misaligned() is on the middle segment being
misaligned, yet the @offset passed in was local_dio->start_len.
It would appear this was a cut-n-paste bug from the preceding
nfs_local_iter_setup() call that passes local_dio->start_len.
Fix this by passing the @offset as local_dio->middle_offset and
calculate the start segment's offset rather than assume.
Example traces, before this fix:
python3-32744 [006] .l... 132946.352360:
nfs_local_dio_write: fileid=00:33:1286 fhandle=0xf1f7c10b
offset=1048759 count=1048576 mem_align=4 offset_align=512
start=1048759+329 middle=1049088+1048064 end=2097152+183
python3-32744 [006] .l... 132946.352360:
nfs_local_dio_misaligned: fileid=00:33:1286 fhandle=0xf1f7c10b
offset=329 count=1048064 mem_align=4 offset_align=512
start=329+329 middle=1049088+1048064 end=2097152+183
After this fix:
python3-32744 [006] .l... 132946.352360:
nfs_local_dio_write: fileid=00:33:1286 fhandle=0xf1f7c10b
offset=1048759 count=1048576 mem_align=4 offset_align=512
start=1048759+329 middle=1049088+1048064 end=2097152+183
python3-32744 [006] .l... 132946.352360:
nfs_local_dio_misaligned: fileid=00:33:1286 fhandle=0xf1f7c10b
offset=1049088 count=1048064 mem_align=4 offset_align=512
start=1048759+329 middle=1049088+1048064 end=2097152+183
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
---
fs/nfs/localio.c | 2 +-
fs/nfs/nfstrace.h | 5 ++++-
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/nfs/localio.c b/fs/nfs/localio.c
index f42b6112a613..63c38dea50cc 100644
--- a/fs/nfs/localio.c
+++ b/fs/nfs/localio.c
@@ -446,7 +446,7 @@ nfs_local_iters_setup_dio(struct nfs_local_kiocb *iocb, int rw,
if (unlikely(!iocb->iter_is_dio_aligned[n_iters])) {
trace_nfs_local_dio_misaligned(iocb->hdr->inode,
- local_dio->start_len, local_dio->middle_len, local_dio);
+ local_dio->middle_offset, local_dio->middle_len, local_dio);
return 0; /* no DIO-aligned IO possible */
}
iocb->end_iter_index = n_iters;
diff --git a/fs/nfs/nfstrace.h b/fs/nfs/nfstrace.h
index c70debb88aa1..2e1932962a81 100644
--- a/fs/nfs/nfstrace.h
+++ b/fs/nfs/nfstrace.h
@@ -1772,7 +1772,10 @@ DECLARE_EVENT_CLASS(nfs_local_dio_class,
__entry->count = count;
__entry->mem_align = local_dio->mem_align;
__entry->offset_align = local_dio->offset_align;
- __entry->start = offset;
+ if (local_dio->start_len)
+ __entry->start = local_dio->middle_offset - local_dio->start_len;
+ else
+ __entry->start = 0;
__entry->start_len = local_dio->start_len;
__entry->middle = local_dio->middle_offset;
__entry->middle_len = local_dio->middle_len;
--
2.43.0
reply other threads:[~2026-07-08 21:36 UTC|newest]
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