Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 7 Jun 2024 07:04:41 +0100 | Subject | Re: [PATCH v3 07/21] fs: xfs: align args->minlen for forced allocation alignment | From | John Garry <> |
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On 06/06/2024 17:22, John Garry wrote: > >> i.e. why didn't it round the start offset down to 48? >> Answering that question will tell you where the bug is. > > After xfs_bmap_compute_alignments() -> xfs_bmap_extsize_align(), > ap->offset=48 - that seems ok. > > Maybe the problem is in xfs_bmap_process_allocated_extent(). For the > problematic case when calling that function: > > args->fsbno=7840 args->len=16 ap->offset=48 orig_offset=56 orig_length=24 > > So, as the comment reads there, we could not satisfy the original length > request, so we move up the position of the extent. > > I assume that we just don't want to do that for forcealign, correct? >
JFYI, after making this following change, my stress test ran overnight:
@@ -3506,13 +3513,15 @@ xfs_bmap_process_allocated_extent( * very fragmented so we're unlikely to be able to satisfy the * hints anyway. */ + if (!xfs_inode_has_forcealign(ap->ip)) { if (ap->length <= orig_length) ap->offset = orig_offset; else if (ap->offset + ap->length < orig_offset + orig_length) ap->offset = orig_offset + orig_length - ap->length; - + } +
>> >> Of course, if the allocation start is rounded down to 48, then >> the length should be rounded up to 32 to cover the entire range we >> are writing new data to.
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