From 1ea352a0db8bcb6ff6820e9a8715aac0aa3c761f Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Mon, 28 Sep 2026 11:54:25 -0400 Subject: [PATCH] NFS/localio: fix nfs_local_dio_misaligned tracepoint 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 Fixes: 6a218b9c3183e ("nfs/localio: do not issue misaligned DIO out-of-order") Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer Signed-off-by: Anna Schumaker --- 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 b15c1732c869..a32c76df72db 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;