xfs/014: try a few times to create speculative preallocations

This test checks that speculative file preallocations are transferred to
threads writing other files when space is low.  Since we have background
threads to clear those preallocations, it's possible that the test
program might not get a speculative preallocation on the first try.

This problem has become more pronounced since the introduction of
background inode inactivation since userspace no longer has direct
control over the timing of file blocks being released from unlinked
files.  As a result, the author has seen an increase in sporadic
warnings from this test about speculative preallocations not appearing.

Therefore, modify the function to try up to five times to create the
speculative preallocation before emitting warnings that then cause
golden output failures.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

diff --git a/tests/xfs/014 b/tests/xfs/014
index a605b359a8cfd28451bf4ab97a6dc53d1449275a..1f0ebac3447ce5facb49053f6ffcaba04e9df729 100755 (executable)
--- a/tests/xfs/014
+++ b/tests/xfs/014
@@ -33,27 +33,36 @@ _cleanup()
 # failure.
 _spec_prealloc_file()
 {
 # failure.
 _spec_prealloc_file()
 {

-       file=$1
-
-       rm -f $file
-
-       # a few file extending open-write-close cycles should be enough to
-       # trigger the fs to retain preallocation. write 256k in 32k intervals to
-       # be sure
-       for i in $(seq 0 32768 262144); do
-               $XFS_IO_PROG -f -c "pwrite $i 32k" $file >> $seqres.full
+       local file=$1
+       local prealloc_size=0
+       local i=0
+
+       # Now that we have background garbage collection processes that can be
+       # triggered by low space/quota conditions, it's possible that we won't
+       # succeed in creating a speculative preallocation on the first try.
+       for ((tries = 0; tries < 5 && prealloc_size == 0; tries++)); do
+               rm -f $file
+
+               # a few file extending open-write-close cycles should be enough
+               # to trigger the fs to retain preallocation. write 256k in 32k
+               # intervals to be sure
+               for i in $(seq 0 32768 262144); do
+                       $XFS_IO_PROG -f -c "pwrite $i 32k" $file >> $seqres.full
+               done
+
+               # write a 4k aligned amount of data to keep the calculations
+               # simple
+               $XFS_IO_PROG -c "pwrite 0 128m" $file >> $seqres.full
+
+               size=`_get_filesize $file`
+               blocks=`stat -c "%b" $file`
+               blocksize=`stat -c "%B" $file`
+
+               prealloc_size=$((blocks * blocksize - size))

        done
 
        done
 

-       # write a 4k aligned amount of data to keep the calculations simple
-       $XFS_IO_PROG -c "pwrite 0 128m" $file >> $seqres.full
-
-       size=`_get_filesize $file`
-       blocks=`stat -c "%b" $file`
-       blocksize=`stat -c "%B" $file`
-
-       prealloc_size=$((blocks * blocksize - size))

        if [ $prealloc_size -eq 0 ]; then
        if [ $prealloc_size -eq 0 ]; then

-               echo "Warning: No speculative preallocation for $file." \
+               echo "Warning: No speculative preallocation for $file after $tries iterations." \

                        "Check use of the allocsize= mount option."
        fi
 
                        "Check use of the allocsize= mount option."
        fi