Re: [PATCH V5 2/2] common/populate: Ensure that S_IFDIR.FMT_BTREE is in btree format

["Darrick J. Wong" <djwong@kernel.org>]

On Sat, Dec 10, 2022 at 09:57:24PM +0800, Zorro Lang wrote:
> On Fri, Dec 09, 2022 at 08:37:41AM -0800, Darrick J. Wong wrote:
> > On Thu, Dec 08, 2022 at 03:28:43PM +0800, Ziyang Zhang 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).
> > > 
> > > Reviewed-by: Zorro Lang <zlang@redhat.com>
> > > Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
> > > Suggested-by: "Darrick J. Wong" <djwong@kernel.org>
> > > Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
> > > Signed-off-by: Ziyang Zhang <ZiyangZhang@linux.alibaba.com>
> > > ---
> > >  common/populate | 34 +++++++++++++++++++++++++++++++++-
> > >  common/xfs      |  9 +++++++++
> > >  2 files changed, 42 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/common/populate b/common/populate
> > > index 6e004997..0d334a13 100644
> > > --- a/common/populate
> > > +++ b/common/populate
> > > @@ -71,6 +71,37 @@ __populate_create_dir() {
> > >  	done
> > >  }
> > >  
> > > +# Create a large directory and ensure that it's a btree format
> > > +__populate_xfs_create_btree_dir() {
> > > +	local name="$1"
> > > +	local isize="$2"
> > > +	local missing="$3"
> > > +	local icore_size="$(_xfs_inode_core_bytes)"
> > 
> > Doesn't this helper require a path argument now?
> 
> What kind of "path" argument? I think he copy it from __populate_create_dir(),
> and keep using the "name" as the root path to create files/dir.

This path argument, from
https://lore.kernel.org/fstests/20221208072843.1866615-2-ZiyangZhang@linux.alibaba.com/T/#u

+# Number of bytes reserved for only the inode record, excluding the
+# immediate fork areas.
+_xfs_get_inode_core_bytes()
+{
+	local dir="$1"
+
+	if _xfs_has_feature "$dir" crc; then

--D

> > 
> > --D
> > 
> > > +	# 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="$(((isize - icore_size) / 16))"
> > > +	local nr=0
> > > +
> > > +	mkdir -p "${name}"
> > > +	while true; do
> > > +		local creat=mkdir
> > > +		test "$((nr % 20))" -eq 0 && creat=touch
> > > +		$creat "${name}/$(printf "%.08d" "$nr")"
> > > +		if [ "$((nr % 40))" -eq 0 ]; then
> > > +			local nextents="$(_xfs_get_fsxattr nextents $name)"
> > > +			[ $nextents -gt $max_nextents ] && break
> > > +		fi
> > > +		nr=$((nr+1))
> > > +	done
> > > +
> > > +	test -z "${missing}" && return
> > > +	seq 1 2 "${nr}" | while read d; do
> > > +		rm -rf "${name}/$(printf "%.08d" "$d")"
> > > +	done
> > > +}
> > > +
> > >  # Add a bunch of attrs to a file
> > >  __populate_create_attr() {
> > >  	name="$1"
> > > @@ -176,6 +207,7 @@ _scratch_xfs_populate() {
> > >  
> > >  	blksz="$(stat -f -c '%s' "${SCRATCH_MNT}")"
> > >  	dblksz="$(_xfs_get_dir_blocksize "$SCRATCH_MNT")"
> > > +	isize="$(_xfs_get_inode_size "$SCRATCH_MNT")"
> > >  	crc="$(_xfs_has_feature "$SCRATCH_MNT" crc -v)"
> > >  	if [ $crc -eq 1 ]; then
> > >  		leaf_hdr_size=64
> > > @@ -226,7 +258,7 @@ _scratch_xfs_populate() {
> > >  
> > >  	# - BTREE
> > >  	echo "+ btree dir"
> > > -	__populate_create_dir "${SCRATCH_MNT}/S_IFDIR.FMT_BTREE" "$((128 * dblksz / 40))" true
> > > +	__populate_xfs_create_btree_dir "${SCRATCH_MNT}/S_IFDIR.FMT_BTREE" "$isize" true
> > >  
> > >  	# Symlinks
> > >  	# - FMT_LOCAL
> > > diff --git a/common/xfs b/common/xfs
> > > index 674384a9..7aaa63c7 100644
> > > --- a/common/xfs
> > > +++ b/common/xfs
> > > @@ -1487,6 +1487,15 @@ _require_xfsrestore_xflag()
> > >  			_notrun 'xfsrestore does not support -x flag.'
> > >  }
> > >  
> > > +# Number of bytes reserved for a full inode record, which includes the
> > > +# immediate fork areas.
> > > +_xfs_get_inode_size()
> > > +{
> > > +	local mntpoint="$1"
> > > +
> > > +	$XFS_INFO_PROG "$mntpoint" | sed -n '/meta-data=.*isize/s/^.*isize=\([0-9]*\).*$/\1/p'
> > > +}
> > > +
> > >  # Number of bytes reserved for only the inode record, excluding the
> > >  # immediate fork areas.
> > >  _xfs_get_inode_core_bytes()
> > > -- 
> > > 2.18.4
> > > 
> > 
>