From ec5fb97d947f42e47d93298e1800112fbd4cdfb0 Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Fri, 1 Nov 2024 13:45:24 +0100 Subject: [PATCH] util.c: add fsync_close() helper, use where appropriate Using genimage directly on an eMMC on target, I'm seeing that the BLKRRPART ioctl fails with EBUSY, presumably because there's still lots of data in flight, and then subsequent parts of my bootstrap procedure fail because the expected partitions can't be found. Whenever we've written some data, we really should ensure that all data has hit the disk before proceeding, and close() itself is not synchronous. Add a fsync_close() helper that does exactly what it says on the tin. Use that wherever we close an fd that has been open for writing and actually written to (i.e., no point in doing that in the reload_partitions() function). Currently, the return value of these close() calls are ignored, so at least for now continue to do that, but at least we do see an error message in case something went wrong. A test case is updated to reflect the new, and more accurate, disk usage. It turns out that the lack of this fsync'ing has really created images which later (long after genimage is done and the test framework has accepted them) would increase in disk usage, i.e. once the kernel gets around to write out any buffered data. With current master, one can observe this: $ mkdir images input tmp $ dd if=/dev/zero of=input/part1.img bs=512 count=7 && dd if=/dev/zero of=input/part2.img bs=512 count=11 && touch input/part3.img $ ./genimage --outputpath=images --inputpath=input --rootpath=/no/such/dir --tmppath=tmp --config test/hdimage.config $ date ; du -B 1 images/test.hdimage-2 Fri Nov 1 08:20:39 PM CET 2024 61440 images/test.hdimage-2 # Let time pass... $ date ; du -B 1 images/test.hdimage-2 Fri Nov 1 08:21:10 PM CET 2024 65536 images/test.hdimage-2 Signed-off-by: Rasmus Villemoes --- test/hdimage.test | 2 +- util.c | 21 +++++++++++++++++---- 2 files changed, 18 insertions(+), 5 deletions(-) diff --git a/test/hdimage.test b/test/hdimage.test index 61e1429..4be3b6c 100755 --- a/test/hdimage.test +++ b/test/hdimage.test @@ -34,7 +34,7 @@ test_expect_success fdisk,sfdisk "hdimage" " test_cmp '${testdir}/hdimage.fdisk' hdimage.fdisk && check_size images/test.hdimage-2 11539968 && sfdisk_validate images/test.hdimage-2 && - check_disk_usage_range images/test.hdimage-2 61290 65376 && + check_disk_usage_range images/test.hdimage-2 61290 65536 && sanitized_fdisk_sfdisk images/test.hdimage-2 > hdimage.fdisk-2 && test_cmp '${testdir}/hdimage.fdisk-2' hdimage.fdisk-2 " diff --git a/util.c b/util.c index 08201f1..fa61ebd 100644 --- a/util.c +++ b/util.c @@ -187,6 +187,19 @@ void debug(const char *fmt, ...) va_end(args); } +static int fsync_close(struct image *image, int fd) +{ + int a, b; + + a = fsync(fd); + if (a) + image_error(image, "fsync() failed: %s\n", strerror(errno)); + b = close(fd); + if (b) + image_error(image, "close() failed: %s\n", strerror(errno)); + return (a || b) ? -1 : 0; +} + /* * printf wrapper around 'system' */ @@ -519,7 +532,7 @@ int prepare_image(struct image *image, unsigned long long size) * than necessary. */ ret = ftruncate(fd, size); - close(fd); + fsync_close(image, fd); if (ret < 0) { ret = -errno; image_error(image, "failed to truncate %s to %lld: %s\n", @@ -634,7 +647,7 @@ int insert_image(struct image *image, struct image *sub, out: if (fd >= 0) - close(fd); + fsync_close(image, fd); if (in_fd >= 0) close(in_fd); free(extents); @@ -671,7 +684,7 @@ int insert_data(struct image *image, const void *_data, const char *outfile, data += now; } err_out: - close(outf); + fsync_close(image, outf); return ret; } @@ -709,7 +722,7 @@ int extend_file(struct image *image, size_t size) } ret = 0; out: - close(f); + fsync_close(image, f); return ret; }