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Re: [Qemu-devel] [PATCH v4 2/5] raw-posix: Factor block size detection o
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH v4 2/5] raw-posix: Factor block size detection out of raw_probe_alignment() |
Date: |
Tue, 16 Dec 2014 17:55:14 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) |
Ekaterina Tumanova <address@hidden> writes:
> Put it in new probe_logical_blocksize().
>
> Signed-off-by: Ekaterina Tumanova <address@hidden>
> ---
> block/raw-posix.c | 41 ++++++++++++++++++++++++-----------------
> 1 file changed, 24 insertions(+), 17 deletions(-)
>
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index e51293a..38172ca 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -217,11 +217,31 @@ static int raw_normalize_devicepath(const char
> **filename)
> }
> #endif
>
> +/*
> + * Get logical block size via ioctl. On success return 0. Otherwise -errno.
> + */
> +static int probe_logical_blocksize(int fd, unsigned int *sector_size)
> +{
> +#if defined(BLKSSZGET)
> +# define SECTOR_SIZE BLKSSZGET
> +#elif defined(DKIOCGETBLOCKSIZE)
> +# define SECTOR_SIZE DKIOCGETBLOCKSIZE
> +#elif defined(DIOCGSECTORSIZE)
> +# define SECTOR_SIZE DIOCGSECTORSIZE
> +#else
> + return -ENOTSUP
> +#endif
> + if (ioctl(fd, SECTOR_SIZE, sector_size) < 0) {
> + return -errno;
> + }
> + return 0;
> +#undef SECTOR_SIZE
> +}
> +
> static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp)
> {
> BDRVRawState *s = bs->opaque;
> char *buf;
> - unsigned int sector_size;
>
> /* For /dev/sg devices the alignment is not really used.
> With buffered I/O, we don't have any restrictions. */
> @@ -231,25 +251,12 @@ static void raw_probe_alignment(BlockDriverState *bs,
> int fd, Error **errp)
> return;
> }
>
> - /* Try a few ioctls to get the right size */
> bs->request_alignment = 0;
> s->buf_align = 0;
> -
> -#ifdef BLKSSZGET
> - if (ioctl(fd, BLKSSZGET, §or_size) >= 0) {
> - bs->request_alignment = sector_size;
> - }
> -#endif
> -#ifdef DKIOCGETBLOCKSIZE
> - if (ioctl(fd, DKIOCGETBLOCKSIZE, §or_size) >= 0) {
> - bs->request_alignment = sector_size;
> + /* Let's try to use the logical blocksize for the alignment. */
> + if (probe_logical_blocksize(fd, &bs->request_alignment) < 0) {
> + bs->request_alignment = 0;
> }
> -#endif
> -#ifdef DIOCGSECTORSIZE
> - if (ioctl(fd, DIOCGSECTORSIZE, §or_size) >= 0) {
> - bs->request_alignment = sector_size;
> - }
> -#endif
> #ifdef CONFIG_XFS
> if (s->is_xfs) {
> struct dioattr da;
New in v4: this isn't just factoring out code, you also change it!
Before: try BLKSSZGET (if defined), DKIOCGETBLOCKSIZE (if defined),
DIOCGSECTORSIZE (if defined) in order until. The last one to succeed
wins. If none succeeds, assume 0.
After: use BLKSSZGET if defined, else try DKIOCGETBLOCKSIZE if defined,
else try DIOCGSECTORSIZE if defined, else assume 0.
Your change may well be an improvement. But your commit message should
explain *why* it's an improvement.
I guess I'd do a separate patch for that, but since the code patch seems
obvious enough as it is, you may just improve its commit message and
call it a day.
- [Qemu-devel] [PATCH v4 0/5] Geometry and blocksize detection for backing devices., Ekaterina Tumanova, 2014/12/16
- [Qemu-devel] [PATCH v4 1/5] block: add bdrv functions for geometry and blocksize, Ekaterina Tumanova, 2014/12/16
- [Qemu-devel] [PATCH v4 2/5] raw-posix: Factor block size detection out of raw_probe_alignment(), Ekaterina Tumanova, 2014/12/16
- Re: [Qemu-devel] [PATCH v4 2/5] raw-posix: Factor block size detection out of raw_probe_alignment(),
Markus Armbruster <=
- [Qemu-devel] [PATCH v4 3/5] block: Add driver methods to probe blocksizes and geometry, Ekaterina Tumanova, 2014/12/16
- [Qemu-devel] [PATCH v4 5/5] BlockConf: Call backend functions to detect geometry and blocksizes, Ekaterina Tumanova, 2014/12/16
- [Qemu-devel] [PATCH v4 4/5] block-backend: Add wrappers for blocksizes and geometry probing, Ekaterina Tumanova, 2014/12/16
- Re: [Qemu-devel] [PATCH v4 0/5] Geometry and blocksize detection for backing devices., Christian Borntraeger, 2014/12/16
- Re: [Qemu-devel] [PATCH v4 0/5] Geometry and blocksize detection for backing devices., Markus Armbruster, 2014/12/16