On Tue, Aug 21, 2012 at 8:23 AM, Cong Meng <m...@linux.vnet.ibm.com> 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 <m...@linux.vnet.ibm.com>
> ---
> 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);
Please handle errors, otherwise *val may be left to uninitialized state.
> + 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"));
> +
I'd init bs->max_sectors etc. here so they are not left uninitialized.
> + ffs = opendir(path);
> + if (!ffs) {
> + return;
> + }
> +
> + for (;;) {
> + d = readdir(ffs);
> + if (!d) {
> + return;
> + }
> +
> + if (strcmp(d->d_name, ".") == 0 || strcmp(d->d_name, "..") == 0) {
> + continue;
> + }
> +
> + break;
> + }
> +
> + 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;
With 32 bit ints and even with 4k sector size, the maximum disk size
would be 16TB which may be soon exceeded by disks on the market.
Please use 64 bit values, probably also for segment values below.
> + 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)
> +{
> + return (bs->file && bs->file->sg) ? bs->file->max_sectors : 0;
> +}
> +
> +unsigned int get_queue_max_segments(BlockDriverState *bs)
> +{
> + return (bs->file && bs->file->sg) ? bs->file->max_segments : 0;
> +}
> +
> +unsigned int get_queue_max_segment_size(BlockDriverState *bs)
> +{
> + return (bs->file && bs->file->sg) ? bs->file->max_segment_size : 0;
> +}
> diff --git a/hw/block-common.h b/hw/block-common.h
> index bb808f7..d47fcd7 100644
> --- a/hw/block-common.h
> +++ b/hw/block-common.h
> @@ -76,4 +76,7 @@ void hd_geometry_guess(BlockDriverState *bs,
> int *ptrans);
> int hd_bios_chs_auto_trans(uint32_t cyls, uint32_t heads, uint32_t secs);
>
> +unsigned int get_queue_max_sectors(BlockDriverState *bs);
> +unsigned int get_queue_max_segments(BlockDriverState *bs);
> +unsigned int get_queue_max_segment_size(BlockDriverState *bs);
> #endif
> --
> 1.7.7.6
>
>
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