test: fat: add test of non-contiguous file reads

In my patch series to replace fs/fat with "ff.c", I enhanced ff.c to
optimize file reading, so that reads of contiguous clusters are submitted
to the IO device as a single read. This test attempts to torture-test
edge-cases of that enhancement.

BTW, the only way I found to validate that this script actually does
create non-contiguous files was to manually inspect the FAT bitmap in a
hex dump of the FAT image. hdparm --fibmap doesn't work on loop-mounted
filesystems. filefrag -v -e seems to lie about files being contiguous
when they aren't.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>

test/fs/fat-noncontig-test.sh

@@ -0,0 +1,113 @@
+#!/bin/bash
+
+# (C) Copyright 2015 Stephen Warren
+#
+# SPDX-License-Identifier:	GPL-2.0+
+
+# This script tests U-Boot's FAT filesystem code's ability to read non-
+# contiguous files.
+
+# When porting the ff.c FAT parsing code into U-Boot, it was found that ff.c
+# always reads files cluster-by-cluster, which results in poor performance.
+# This was solved by adding a patch to ff.c to coalesce reads of adjacent
+# clusters. Since this patch needed to correctly handle non-contiguous files,
+# this test was written to validate that.
+#
+# To execute the test, simply run it from the U-Boot source root directory:
+#
+#    cd u-boot
+#    ./test/fs/fat-noncontig-test.sh
+#
+# The test will create a FAT filesystem image, record the CRC of a randomly
+# generated file in the image, build U-Boot sandbox, invoke U-Boot sandbox to
+# read the file and validate that the CRCs match. Expected output is shown
+# below. The important part of the log is the penultimate line that contains
+# either "PASS" or "FAILURE".
+#
+#    mkfs.fat 3.0.26 (2014-03-07)
+#
+#
+#    U-Boot 2015.10-rc4-00018-g4b22a3e5513f (Oct 03 2015 - 13:49:23 -0600)
+#
+#    DRAM:  128 MiB
+#    Using default environment
+#
+#    In:    serial
+#    Out:   lcd
+#    Err:   lcd
+#    Net:   No ethernet found.
+#    => host bind 0 sandbox/fat-noncontig.img
+#    => load host 0:0 1000 noncontig.img
+#    33584964 bytes read in 18 ms (1.7 GiB/s)
+#    => crc32 1000 $filesize 0
+#    crc32 for 00001000 ... 02008743 ==> 6a080523
+#    => if itest.l *0 != 2305086a; then echo FAILURE; else echo PASS; fi
+#    PASS
+#    => reset
+#
+# All temporary files used by this script are created in ./sandbox to avoid
+# polluting the source tree. test/fs/fs-test.sh also uses this directory for
+# the same purpose.
+#
+# TODO: Integrate this (and many other corner-cases e.g. different types of
+# FAT) with fs-test.sh so that a single script tests everything filesystem-
+# related.
+
+odir=sandbox
+img=${odir}/fat-noncontig.img
+mnt=${odir}/mnt
+fill=/dev/urandom
+testfn=noncontig.img
+mnttestfn=${mnt}/${testfn}
+crcaddr=0
+loadaddr=1000
+
+for prereq in fallocate mkfs.fat dd crc32; do
+    if [ ! -x "`which $prereq`" ]; then
+        echo "Missing $prereq binary. Exiting!"
+        exit 1
+    fi
+done
+
+make O=${odir} -s sandbox_defconfig && make O=${odir} -s -j8
+
+mkdir -p ${mnt}
+if [ ! -f ${img} ]; then
+    fallocate -l 40M ${img}
+    mkfs.fat ${img}
+
+    sudo mount -o loop,uid=$(id -u) ${img} ${mnt}
+
+    for ((sects=8; sects < 512; sects += 8)); do
+        fn=${mnt}/keep-${sects}.img
+        dd if=${fill} of=${fn} bs=512 count=${sects} >/dev/null 2>&1
+        fn=${mnt}/remove-${sects}.img
+        dd if=${fill} of=${fn} bs=512 count=${sects} >/dev/null 2>&1
+    done
+
+    rm -f ${mnt}/remove-*.img
+
+    # 511 deliberately to trigger a file size that's not a multiple of the
+    # sector size (ignoring sizes that are multiples of both).
+    dd if=${fill} of=${mnttestfn} bs=511 >/dev/null 2>&1
+
+    sudo umount ${mnt}
+fi
+
+sudo mount -o ro,loop,uid=$(id -u) ${img} ${mnt}
+crc=0x`crc32 ${mnttestfn}`
+sudo umount ${mnt}
+
+crc=`printf %02x%02x%02x%02x \
+    $((${crc} & 0xff)) \
+    $(((${crc} >> 8) & 0xff)) \
+    $(((${crc} >> 16) & 0xff)) \
+    $((${crc} >> 24))`
+
+./sandbox/u-boot << EOF
+host bind 0 ${img}
+load host 0:0 ${loadaddr} ${testfn}
+crc32 ${loadaddr} \$filesize ${crcaddr}
+if itest.l *${crcaddr} != ${crc}; then echo FAILURE; else echo PASS; fi
+reset
+EOF