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NFS/localio: fix nfs_local_dio_misaligned tracepoint

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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: 6a218b9c31 ("nfs/localio: do not issue misaligned DIO out-of-order")
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@hammerspace.com>
This commit is contained in:
Mike Snitzer 2026-09-28 11:54:25 -04:00 committed by Anna Schumaker
parent 4fa21ed151
commit 1ea352a0db
2 changed files with 5 additions and 2 deletions
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2
fs/nfs/localio.c
View File

@ -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;

5
fs/nfs/nfstrace.h
View File

@ -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;