On Mon, Jun 27, 2022 at 08:19:15AM +0800, Sam Li wrote:
> Use sysfs attribute files to get the zoned device information in case
> that ioctl() commands of zone management interface won't work. It can
> return long type of value like chunk_sectors, zoned_append_max_bytes,
> max_open_zones, max_active_zones.
> ---
> block/file-posix.c | 37 +++++++++++++++++++++++++------------
> 1 file changed, 25 insertions(+), 12 deletions(-)
>
> diff --git a/block/file-posix.c b/block/file-posix.c
> index 1b8b0d351f..73c2cdfbca 100644
> --- a/block/file-posix.c
> +++ b/block/file-posix.c
> @@ -1216,15 +1216,19 @@ static int hdev_get_max_hw_transfer(int fd, struct
> stat *st)
> #endif
> }
>
> -static int hdev_get_max_segments(int fd, struct stat *st)
> -{
> +/*
> + * Get zoned device information (chunk_sectors, zoned_append_max_bytes,
> + * max_open_zones, max_active_zones) through sysfs attribute files.
This function is also used to get max_segments, which is not related to
zoned devices. How about:
Get a block queue sysfs attribute value.
> + */
> +static long get_sysfs_long_val(int fd, struct stat *st,
> + const char *attribute) {
> #ifdef CONFIG_LINUX
> char buf[32];
> const char *end;
> char *sysfspath = NULL;
> int ret;
> int sysfd = -1;
> - long max_segments;
> + long val;
>
> if (S_ISCHR(st->st_mode)) {
> if (ioctl(fd, SG_GET_SG_TABLESIZE, &ret) == 0) {
> @@ -1237,8 +1241,9 @@ static int hdev_get_max_segments(int fd, struct stat
> *st)
> return -ENOTSUP;
> }
>
> - sysfspath = g_strdup_printf("/sys/dev/block/%u:%u/queue/max_segments",
> - major(st->st_rdev), minor(st->st_rdev));
> + sysfspath = g_strdup_printf("/sys/dev/block/%u:%u/queue/%s",
> + major(st->st_rdev), minor(st->st_rdev),
> + attribute);
> sysfd = open(sysfspath, O_RDONLY);
> if (sysfd == -1) {
> ret = -errno;
> @@ -1256,9 +1261,9 @@ static int hdev_get_max_segments(int fd, struct stat
> *st)
> }
> buf[ret] = 0;
> /* The file is ended with '\n', pass 'end' to accept that. */
> - ret = qemu_strtol(buf, &end, 10, &max_segments);
> + ret = qemu_strtol(buf, &end, 10, &val);
> if (ret == 0 && end && *end == '\n') {
> - ret = max_segments;
> + ret = val;
> }
>
> out:
> @@ -1272,6 +1277,15 @@ out:
> #endif
> }
>
> +static int hdev_get_max_segments(int fd, struct stat *st) {
> + int ret;
> + ret = get_sysfs_long_val(fd, st, "max_segments");
> + if (ret < 0) {
> + return -1;
This hides the actual error number. The if statement can be dropped and
the function can be simplified to:
static int hdev_get_max_segments(int fd, struct stat *st) {
return get_sysfs_long_val(fd, st, "max_segments");
}
Whether you want to keep the tiny helper function or inline
get_sysfs_long_val(fd, st, "max_segments") into the caller is up to you.
> + }
> + return ret;
> +}
> +
> static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
> {
> BDRVRawState *s = bs->opaque;
> @@ -1872,6 +1886,7 @@ static int handle_aiocb_zone_report(void *opaque) {
>
> static int handle_aiocb_zone_mgmt(void *opaque) {
> RawPosixAIOData *aiocb = opaque;
> + BlockDriverState *s = aiocb->bs;
> int fd = aiocb->aio_fildes;
> int64_t offset = aiocb->aio_offset;
> int64_t len = aiocb->aio_nbytes;
> @@ -1884,11 +1899,9 @@ static int handle_aiocb_zone_mgmt(void *opaque) {
> int64_t zone_size_mask;
> int ret;
>
> - ret = ioctl(fd, BLKGETZONESZ, &zone_size);
> - if (ret) {
> - return -1;
> - }
> -
> + g_autofree struct stat *file = g_new(struct stat, 1);
> + stat(s->filename, file);
There is no need to allocate struct stat using g_new(). It's a small
struct that can be on the stack.
Also, fstat(fd, &st) is preferred when the file descriptor is already
open because it avoids race conditions due to file renaming/path
traversal.
Here is how this could be written:
struct stat st;
if (fstat(fd, &st) < 0) {
return -errno;
}
> + zone_size = get_sysfs_long_val(fd, file, "chunk_sectors");
> zone_size_mask = zone_size - 1;
> if (offset & zone_size_mask) {
> error_report("offset is not the start of a zone");
> --
> 2.35.3
>
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