On Thu, Apr 15, 2021 at 01:30:11PM +0800, Qu Wenruo wrote:
> Currently mkfs.btrfs will output a warning message if the sectorsize is
> not the same as page size:
> WARNING: the filesystem may not be mountable, sectorsize 4096 doesn't match
> page size 65536
>
> But since btrfs subpage support for 64K page size is comming, this
> output is populating the golden output of fstests, causing tons of false
> alerts.
>
> This patch will make teach mkfs.btrfs to check
> /sys/fs/btrfs/features/supported_sectorsizes, and compare if the sector
> size is supported.
>
> Then only output above warning message if the sector size is not
> supported.
>
> Signed-off-by: Qu Wenruo <w...@suse.com>
> ---
> common/fsfeatures.c | 36 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/common/fsfeatures.c b/common/fsfeatures.c
> index 569208a9e5b1..13b775da9c72 100644
> --- a/common/fsfeatures.c
> +++ b/common/fsfeatures.c
> @@ -16,6 +16,8 @@
>
> #include "kerncompat.h"
> #include <sys/utsname.h>
> +#include <sys/stat.h>
> +#include <fcntl.h>
> #include <linux/version.h>
> #include <unistd.h>
> #include "common/fsfeatures.h"
> @@ -327,8 +329,15 @@ u32 get_running_kernel_version(void)
>
> return version;
> }
> +
> +/*
> + * The buffer size if strlen("4096 8192 16384 32768 65536"),
> + * which is 28, then round up to 32.
> + */
> +#define SUPPORTED_SECTORSIZE_BUF_SIZE 32
> int btrfs_check_sectorsize(u32 sectorsize)
> {
> + bool sectorsize_checked = false;
> u32 page_size = (u32)sysconf(_SC_PAGESIZE);
>
> if (!is_power_of_2(sectorsize)) {
> @@ -340,7 +349,32 @@ int btrfs_check_sectorsize(u32 sectorsize)
> sectorsize);
> return -EINVAL;
> }
> - if (page_size != sectorsize)
> + if (page_size == sectorsize) {
> + sectorsize_checked = true;
> + } else {
> + /*
> + * Check if the sector size is supported
> + */
> + char supported_buf[SUPPORTED_SECTORSIZE_BUF_SIZE] = { 0 };
> + char sectorsize_buf[SUPPORTED_SECTORSIZE_BUF_SIZE] = { 0 };
> + int fd;
> + int ret;
> +
> + fd = open("/sys/fs/btrfs/features/supported_sectorsizes",
> + O_RDONLY);
> + if (fd < 0)
> + goto out;
> + ret = read(fd, supported_buf, sizeof(supported_buf));
> + close(fd);
There are some sysfs helpers, like sysfs_read_file and
sysfs_open_fsid_file that would avoid the boilerplate code. We don't
have a helper for the toplevel sysfs directory so that would need to be
added first.
Now that I look at it, the sysfs_read_file could actually do that in one
go, including open and close. I'll probably do that as a cleanup later
and apply your patch as it's a fix. Thanks.
