Hi Darrick, On Thu, Dec 01, 2022 at 07:52:44AM -0800, Darrick J. Wong wrote: > On Thu, Dec 01, 2022 at 04:12:08PM +0800, Gao Xiang wrote: > > Sometimes "$((128 * dblksz / 40))" dirents cannot make sure that > > S_IFDIR.FMT_BTREE could become btree format for its DATA fork. > > > > Actually we just observed it can fail after apply our inode > > extent-to-btree workaround. The root cause is that the kernel may be > > too good at allocating consecutive blocks so that the data fork is > > still in extents format. > > > > Therefore instead of using a fixed number, let's make sure the number > > of extents is large enough than (inode size - inode core size) / > > sizeof(xfs_bmbt_rec_t). > > > > Suggested-by: "Darrick J. Wong" <djwong@xxxxxxxxxx> > > Cc: Ziyang Zhang <ZiyangZhang@xxxxxxxxxxxxxxxxx> > > Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> > > --- > > common/populate | 22 +++++++++++++++++++++- > > 1 file changed, 21 insertions(+), 1 deletion(-) > > > > diff --git a/common/populate b/common/populate > > index 6e004997..e179a300 100644 > > --- a/common/populate > > +++ b/common/populate > > @@ -71,6 +71,25 @@ __populate_create_dir() { > > done > > } > > > > +# Create a large directory and ensure that it's a btree format > > +__populate_create_btree_dir() { > > Since this encodes behavior specific to xfs, this ought to be called > > __populate_xfs_create_btree_dir > > or something like that. > > > + name="$1" > > + isize="$2" > > These ought to be local variables, e.g. > > local name="$1" > local isize="$2" > > So that they don't pollute the global name scope. Yay bash. > > > + > > + mkdir -p "${name}" > > + d=0 > > + while true; do > > + creat=mkdir > > + test "$((d % 20))" -eq 0 && creat=touch > > + $creat "${name}/$(printf "%.08d" "$d")" > > + if [ "$((d % 40))" -eq 0 ]; then > > + nexts="$($XFS_IO_PROG -c "stat" $name | grep 'fsxattr.nextents' | sed -e 's/^.*nextents = //g' -e 's/\([0-9]*\).*$/\1/g')" > > _xfs_get_fsxattr... > > > + [ "$nexts" -gt "$(((isize - 176) / 16))" ] && break > > Only need to calculate this once if you declare this at the top: > > # We need enough extents to guarantee that the data fork is in > # btree format. Cycling the mount to use xfs_db is too slow, so > # watch for when the extent count exceeds the space after the > # inode core. > local max_nextents="$(((isize - 176) / 16))" > > and then you can do: > > [[ $nexts -gt $max_nextents ]] && break > > Also not a fan of hardcoding 176 around fstests, but I don't know how > we'd detect that at all. > > # Number of bytes reserved for only the inode record, excluding the > # immediate fork areas. > _xfs_inode_core_bytes() > { > echo 176 > } > > I guess? Or extract it from tests/xfs/122.out? Thanks for your comments. I guess hard-coded 176 in _xfs_inode_core_bytes() is fine for now (It seems a bit weird to extract a number from a test expected result..) Otherwise I agree with your comments. I will ask Ziyang to follow your comments and send out v2. Thanks, Gao Xiang