From: Darrick J. Wong <djwong@xxxxxxxxxx>
The formulae used to compute the number of parent pointers that we have
to create in a child file in order to generate a particular xattr
structure are not even close to correct -- the first one needs a bit of
adjustment, but the second one is way off and creates far too many
files.
Fix the computation, and document where the magic numbers come from.
Cc: <fstests@xxxxxxxxxxxxxxx> # v2024.06.27
Fixes: 0c02207d61af9a ("populate: create hardlinks for parent pointers")
Signed-off-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
---
common/populate | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/common/populate b/common/populate
index 4cf9c0691956a3..c907e04efd0ea9 100644
--- a/common/populate
+++ b/common/populate
@@ -473,13 +473,18 @@ _scratch_xfs_populate() {
__populate_create_dir "${SCRATCH_MNT}/PPTRS" 1 '' \
--hardlink --format "two_%d"
- # Create one xattr leaf block of parent pointers
- nr="$((blksz * 2 / 16))"
+ # Create one xattr leaf block of parent pointers. The name is
+ # 8 bytes and, the handle is 12 bytes, which rounds up to 24
+ # bytes per record, plus xattr structure overhead.
+ nr="$((blksz / 24))"
__populate_create_dir "${SCRATCH_MNT}/PPTRS" ${nr} '' \
--hardlink --format "many%04d"
- # Create multiple xattr leaf blocks of large parent pointers
- nr="$((blksz * 16 / 16))"
+ # Create multiple xattr leaf blocks of large parent pointers.
+ # The name is 256 bytes and the handle is 12 bytes, which
+ # rounds up to 272 bytes per record, plus xattr structure
+ # overhead.
+ nr="$((blksz * 2 / 272))"
__populate_create_dir "${SCRATCH_MNT}/PPTRS" ${nr} '' \
--hardlink --format "y%0254d"
