On Tue, Aug 21, 2012 at 9:23 AM, Cong Meng <mc@xxxxxxxxxxxxxxxxxx> wrote:
> This patch adds some queue limit parameters into block drive. And inits them
> for sg block drive. Some interfaces are also added for accessing them.
>
> Signed-off-by: Cong Meng <mc@xxxxxxxxxxxxxxxxxx>
> ---
> block/raw-posix.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> block_int.h | 4 +++
> blockdev.c | 15 +++++++++++++
> hw/block-common.h | 3 ++
> 4 files changed, 80 insertions(+), 0 deletions(-)
>
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index 0dce089..a086f89 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -53,6 +53,7 @@
> #include <linux/cdrom.h>
> #include <linux/fd.h>
> #include <linux/fs.h>
> +#include <dirent.h>
> #endif
> #ifdef CONFIG_FIEMAP
> #include <linux/fiemap.h>
> @@ -829,6 +830,62 @@ static int hdev_probe_device(const char *filename)
> return 0;
> }
>
> +static void read_queue_limit(char *path, const char *filename, unsigned int *val)
> +{
> + FILE *f;
> + char *tail = path + strlen(path);
> +
> + pstrcat(path, MAXPATHLEN, filename);
> + f = fopen(path, "r");
> + if (!f) {
> + goto out;
> + }
> +
> + fscanf(f, "%u", val);
> + fclose(f);
> +
> +out:
> + *tail = 0;
> +}
> +
> +static void sg_get_queue_limits(BlockDriverState *bs, const char *filename)
> +{
> + DIR *ffs;
> + struct dirent *d;
> + char path[MAXPATHLEN];
> +
> + snprintf(path, MAXPATHLEN,
> + "/sys/class/scsi_generic/sg%s/device/block/",
> + filename + strlen("/dev/sg"));
> +
> + ffs = opendir(path);
> + if (!ffs) {
> + return;
> + }
> +
> + for (;;) {
> + d = readdir(ffs);
> + if (!d) {
> + return;
Leaks ffs
> + }
> +
> + if (strcmp(d->d_name, ".") == 0 || strcmp(d->d_name, "..") == 0) {
> + continue;
> + }
> +
> + break;
> + }
Not sure where in the kernel the block/ sysfs directory is created for
the device. I wasn't able to check that there is only ever 1
directory entry for a SCSI device's block/. Any ideas whether it's
safe to grab the first directory entry?
> +
> + closedir(ffs);
> +
> + pstrcat(path, MAXPATHLEN, d->d_name);
> + pstrcat(path, MAXPATHLEN, "/queue/");
> +
> + read_queue_limit(path, "max_sectors_kb", &bs->max_sectors);
> + read_queue_limit(path, "max_segments", &bs->max_segments);
> + read_queue_limit(path, "max_segment_size", &bs->max_segment_size);
> +}
> +
> static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
> {
> BDRVRawState *s = bs->opaque;
> @@ -868,6 +925,7 @@ static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
> temp = realpath(filename, resolved_path);
> if (temp && strstart(temp, "/dev/sg", NULL)) {
> bs->sg = 1;
> + sg_get_queue_limits(bs, temp);
> }
> }
> #endif
> diff --git a/block_int.h b/block_int.h
> index d72317f..a9d07a2 100644
> --- a/block_int.h
> +++ b/block_int.h
> @@ -333,6 +333,10 @@ struct BlockDriverState {
>
> /* long-running background operation */
> BlockJob *job;
> +
> + unsigned int max_sectors;
> + unsigned int max_segments;
> + unsigned int max_segment_size;
> };
>
> int get_tmp_filename(char *filename, int size);
> diff --git a/blockdev.c b/blockdev.c
> index 3d75015..e17edbf 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -1191,3 +1191,18 @@ BlockJobInfoList *qmp_query_block_jobs(Error **errp)
> bdrv_iterate(do_qmp_query_block_jobs_one, &prev);
> return dummy.next;
> }
> +
> +unsigned int get_queue_max_sectors(BlockDriverState *bs)
These should be bdrv_get_queue_max_sectors(BlockDriverState *bs) and
should live in block.c.
> +{
> + return (bs->file && bs->file->sg) ? bs->file->max_sectors : 0;
The BlockDriver should be able to provide these values, we shouldn't
reach into bs->file.
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