| Message ID | 162561730547.543423.5029188797370208051.stgit@locust (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fstests: random fixes | expand |
On 7/6/21 5:21 PM, Darrick J. Wong wrote: > From: Darrick J. Wong <djwong@kernel.org> > > Once in a very long while, the fallocate calls in this test will fail > due to ENOSPC conditions. While in theory this test is careful only to > allocate at most 160M of space from a 256M filesystem, there's a twist > on XFS: speculative preallocation. > > The first loop in this test is an 80M appending write done in units of > 4k. Once the file size hits 64k, XFS will begin speculatively > preallocating blocks past the end of the file; as the file grows larger, > so will the speculative preallocation. > > Since the pwrite/rm loop races with the fallocate/rm loop, it's possible > that the fallocate loop will free that file just before the buffered > write extends the speculative preallocation out to 160MB. With fs and > log overhead, that doesn't leave enough free space to start the 80MB > fallocate request, which tries to avoid disappointing the caller by > freeing all speculative preallocations. That fails if the pwriter > thread owns the IOLOCK on $testfile1, so fallocate returns ENOSPC and > the test fails. > > The simple solution here is to disable speculative preallocation by > setting an extent size hint if the fs is XFS. > Ok, makes sense Reviewed-by: Allison Henderson <allison.henderson@oracle.com> > Signed-off-by: Darrick J. Wong <djwong@kernel.org> > --- > tests/generic/371 | 8 ++++++++ > 1 file changed, 8 insertions(+) > > > diff --git a/tests/generic/371 b/tests/generic/371 > index c94fa85e..a2fdaf7b 100755 > --- a/tests/generic/371 > +++ b/tests/generic/371 > @@ -18,10 +18,18 @@ _begin_fstest auto quick enospc prealloc > _supported_fs generic > _require_scratch > _require_xfs_io_command "falloc" > +test "$FSTYP" = "xfs" && _require_xfs_io_command "extsize" > > _scratch_mkfs_sized $((256 * 1024 * 1024)) >> $seqres.full 2>&1 > _scratch_mount > > +# Disable speculative post-EOF preallocation on XFS, which can grow fast enough > +# that a racing fallocate then fails. > +if [ "$FSTYP" = "xfs" ]; then > + alloc_sz="$(_get_file_block_size $SCRATCH_MNT)" > + $XFS_IO_PROG -c "extsize $alloc_sz" $SCRATCH_MNT >> $seqres.full > +fi > + > testfile1=$SCRATCH_MNT/testfile1 > testfile2=$SCRATCH_MNT/testfile2 > >
diff --git a/tests/generic/371 b/tests/generic/371 index c94fa85e..a2fdaf7b 100755 --- a/tests/generic/371 +++ b/tests/generic/371 @@ -18,10 +18,18 @@ _begin_fstest auto quick enospc prealloc _supported_fs generic _require_scratch _require_xfs_io_command "falloc" +test "$FSTYP" = "xfs" && _require_xfs_io_command "extsize" _scratch_mkfs_sized $((256 * 1024 * 1024)) >> $seqres.full 2>&1 _scratch_mount +# Disable speculative post-EOF preallocation on XFS, which can grow fast enough +# that a racing fallocate then fails. +if [ "$FSTYP" = "xfs" ]; then + alloc_sz="$(_get_file_block_size $SCRATCH_MNT)" + $XFS_IO_PROG -c "extsize $alloc_sz" $SCRATCH_MNT >> $seqres.full +fi + testfile1=$SCRATCH_MNT/testfile1 testfile2=$SCRATCH_MNT/testfile2