On Fri, Aug 16, 2024 at 10:18:43AM +0200, Christoph Hellwig wrote:
> Fix the newly added discard support to only offer a FITRIM range that
> spans the RT device in addition to the main device if the RT device
> actually supports discard. Without this we'll incorrectly accept
> a larger range than actually supported and confuse user space if the
> RT device does not support discard. This can easily happen when the
> main device is a SSD but the RT device is a hard driver.
>
> Move the code around a bit to keep the max_blocks and granularity
> assignments together and explicitly reject that case where only the
> RT device supports discard, as that does not fit the way the FITRIM ABI
> works very well and is a very fringe use case.
Is there more to this than generic/260 failing? And if not, does the
following patch things up for you?
--D
From: Darrick J. Wong <djwong@xxxxxxxxxx>
Subject: [PATCH] generic/260: fix for multi-device xfs with mixed discard support
Fix this test so that it can handle XFS filesystems with a realtime
volume when the data and rt devices do not both support discard.
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
common/rc | 12 ++++++++++-
common/xfs | 65 +++++++++++++++++++++++++++++++++++++++++++++++++-----------
2 files changed, 64 insertions(+), 13 deletions(-)
diff --git a/common/rc b/common/rc
index b718030a59..426f2de43b 100644
--- a/common/rc
+++ b/common/rc
@@ -4207,6 +4207,16 @@ _require_batched_discard()
fi
}
+_bdev_queue_property()
+{
+ local dev="$1"
+ local property="$2"
+ local default="$3"
+
+ local fname="/sys/block/$(_short_dev "$dev")/queue/$property"
+ cat "$fname" 2>/dev/null || echo "$default"
+}
+
# Given a mountpoint and the device associated with that mountpoint, return the
# maximum start offset that the FITRIM command will accept, in units of 1024
# byte blocks.
@@ -4214,7 +4224,7 @@ _discard_max_offset_kb()
{
case "$FSTYP" in
xfs)
- _xfs_discard_max_offset_kb "$1"
+ _xfs_discard_max_offset_kb "$@"
;;
*)
$DF_PROG -k | awk -v dev="$2" -v mnt="$1" '$1 == dev && $7 == mnt { print $3 }'
diff --git a/common/xfs b/common/xfs
index 9501adac4c..5ad60a3ddc 100644
--- a/common/xfs
+++ b/common/xfs
@@ -1882,7 +1882,13 @@ _require_xfs_scratch_atomicswap()
# of 1024 byte blocks.
_xfs_discard_max_offset_kb()
{
+ local mount="$1"
+ local dev="$2"
local statfs
+ local datadev_discard=
+ local rtdev_discard=
+ local dev_discard_max=
+ local rtdev_discard_max=
# Use awk to read the statfs output for the XFS filesystem, compute
# the two possible FITRIM offset maximums, and then use some horrid
@@ -1895,31 +1901,66 @@ _xfs_discard_max_offset_kb()
# 2: Realtime volume size in fsblocks.
# 3: Max FITRIM offset if we can only trim the data volume
# 4: Max FITRIM offset if we can trim the data and rt volumes
- readarray -t statfs < <($XFS_IO_PROG -c 'statfs' "$1" | \
- awk '{g[$1] = $3} END {printf("%d\n%d\n%d\n%d\n%d\n",
+ # 5: Max FITRIM offset if we can only trim the rt volume
+ readarray -t statfs < <($XFS_IO_PROG -c 'statfs' "$mount" | \
+ awk '{g[$1] = $3} END {printf("%d\n%d\n%d\n%d\n%d\n%d\n",
g["geom.bsize"],
g["geom.datablocks"],
g["geom.rtblocks"],
g["geom.bsize"] * g["geom.datablocks"] / 1024,
- g["geom.bsize"] * (g["geom.datablocks"] + g["geom.rtblocks"]) / 1024);}')
+ g["geom.bsize"] * (g["geom.datablocks"] + g["geom.rtblocks"]) / 1024,
+ g["geom.bsize"] * g["geom.rtblocks"] / 1024);}')
# If the kernel supports discarding the realtime volume, then it will
# not reject a FITRIM for fsblock dblks+1, even if the len/minlen
# arguments are absurd.
if [ "${statfs[2]}" -gt 0 ]; then
- if $FSTRIM_PROG -o "$((statfs[0] * statfs[1]))" \
+ case "$dev" in
+ "$SCRATCH_DEV")
+ rtdev_discard_max="$(_bdev_queue_property "$SCRATCH_RTDEV" discard_max_bytes 0)"
+ ;;
+ "$TEST_DEV")
+ rtdev_discard_max="$(_bdev_queue_property "$TEST_RTDEV" discard_max_bytes 0)"
+ ;;
+ *)
+ echo "Unrecognized device $dev" >&2
+ rtdev_discard_max=0
+ ;;
+ esac
+
+ if [ "$rtdev_discard_max" -gt 0 ] &&
+ $FSTRIM_PROG -o "$((statfs[0] * statfs[1]))" \
-l "${statfs[0]}" \
- -m "$((statfs[0] * 2))" "$1" &>/dev/null; then
- # The kernel supports discarding the rt volume, so
- # print out the second answer from above.
- echo "${statfs[4]}"
- return
+ -m "$((statfs[0] * 2))" "$mount" &>/dev/null; then
+ # The kernel supports discarding the rt volume
+ rtdev_discard=2
fi
fi
- # The kernel does not support discarding the rt volume or there is no
- # rt volume. Print out the first answer from above.
- echo "${statfs[3]}"
+ # The kernel supports discarding the rt volume
+ dev_discard_max="$(_bdev_queue_property "$dev" discard_max_bytes 0)"
+ if [ "$dev_discard_max" -gt 0 ]; then
+ datadev_discard=1
+ fi
+
+ case "$datadev_discard$rtdev_discard" in
+ "12")
+ # Both devices support it
+ echo "${statfs[4]}"
+ ;;
+ "1")
+ # Only the data device supports it
+ echo "${statfs[3]}"
+ ;;
+ "2")
+ # Only the rt device supports it
+ echo "${statfs[5]}"
+ ;;
+ *)
+ # No support at all
+ echo 0
+ ;;
+ esac
}
# check if mkfs and the kernel support nocrc (v4) file systems
