From: Filipe Manana <fdmanana@xxxxxxxx>
This test currently always fails on btrfs:
generic/471 2s ... - output mismatch (see ...results//generic/471.out.bad)
--- tests/generic/471.out 2020-06-10 19:29:03.850519863 +0100
+++ /home/fdmanana/git/hub/xfstests/results//generic/471.out.bad ...
@@ -2,12 +2,10 @@
pwrite: Resource temporarily unavailable
wrote 8388608/8388608 bytes at offset 0
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-RWF_NOWAIT time is within limits.
+pwrite: Resource temporarily unavailable
+(standard_in) 1: syntax error
+RWF_NOWAIT took seconds
This is because btrfs is a COW filesystem and an attempt to write into a
previously written file range allocating a new extent (or multiple).
The only exceptions are when attempting to write to a file range with a
preallocated/unwritten extent or when writing to a NOCOW file that has
extents allocated in the target range already.
The test currently expects that writing into a previously written file
range succeeds, but that is not true on btrfs since we are not dealing
with a NOCOW file. So to make the test pass on btrfs, set the NOCOW bit
on the file when the filesystem is btrfs.
Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
---
tests/generic/471 | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/tests/generic/471 b/tests/generic/471
index 7513f023..e9856b52 100755
--- a/tests/generic/471
+++ b/tests/generic/471
@@ -37,6 +37,17 @@ fi
mkdir $testdir
+# Btrfs is a COW filesystem, so a RWF_NOWAIT write will always fail with -EAGAIN
+# when writing to a file range except if it's a NOCOW file and an extent for the
+# range already exists or if it's a COW file and preallocated/unwritten extent
+# exists in the target range. So to make sure that the last write succeeds on
+# all filesystems, use a NOCOW file on btrfs.
+if [ $FSTYP == "btrfs" ]; then
+ _require_chattr C
+ touch $testdir/f1
+ $CHATTR_PROG +C $testdir/f1
+fi
+
# Create a file with pwrite nowait (will fail with EAGAIN)
$XFS_IO_PROG -f -d -c "pwrite -N -V 1 -b 1M 0 1M" $testdir/f1
--
2.26.2
