On Thu, Dec 03, 2015 at 05:16:46PM -0600, Eric Sandeen wrote:
> Now that we allow logical-sector-sized DIOs even if our xfs
> filesystem is set to physical-sector-sized "sectors," we can
> allow the creation of filesystem images with block and sector
> sizes down to the host device's logical sector size, rather
> than the filesystem's sector size.
>
> So in platform_findsizes(), change our query of the filesystem
> to a query of the device, and use that for sector size in the
> S_IFREG case.
>
> This allows the creation of i.e. a 2k block sized image on
> an xfs filesystem w/ 4k sector size created on a 4k/512
> block device, which would otherwise fail today.
>
> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
>
> This feels like about my 5th stab at this; it seems like
> the correct thing to do but by now my brain is full.
> Seem sane?
I'm not sure I like the idea of encoding blkid functionality
into libxfs, especially as blkid support is optional:
commit 6635d6ab510c58996f5ed3f212148db5e3c299ba
Author: Jan Tulak <jtulak@xxxxxxxxxx>
Date: Wed Oct 14 10:57:39 2015 +1100
build: make libblkid usage optional
> Still needs a run through xfstests but wanted to see if this
> was obviously bonkers or not...?
>
> (I don't know why copy/Makefile needs a $(LIBBLKID), either...)
Because libxfs now has a dependency on libblkid, and libxfs is a
static library so it doesn't resolve undefined extern objects as the
library is built. That is only done when linking binaries....
> index 885016a..3a8dc12 100644
> --- a/libxfs/linux.c
> +++ b/libxfs/linux.c
> @@ -24,6 +24,7 @@
> #include <sys/mount.h>
> #include <sys/ioctl.h>
> #include <sys/sysinfo.h>
> +#include <blkid/blkid.h>
>
> #include "libxfs_priv.h"
> #include "xfs_fs.h"
> @@ -142,18 +143,29 @@ platform_findsizes(char *path, int fd, long long *sz, int *bsz)
> progname, path, strerror(errno));
> exit(1);
> }
> +
> if ((st.st_mode & S_IFMT) == S_IFREG) {
> - struct xfs_fsop_geom_v1 geom = { 0 };
> + int fd;
> + char *hostfs_dev_path; /* path to host fs device */
>
> *sz = (long long)(st.st_size >> 9);
> - if (ioctl(fd, XFS_IOC_FSGEOMETRY_V1, &geom) < 0) {
> - /*
> - * fall back to BBSIZE; mkfs might fail if there's a
> - * size mismatch between the image & the host fs...
> - */
> - *bsz = BBSIZE;
> - } else
> - *bsz = geom.sectsize;
> +
> + /*
> + * Default to BBSIZE; mkfs might fail if there's a
> + * size mismatch between the image & the host fs...
> + */
> + *bsz = BBSIZE;
> +
> + /* Get logical sector size of host device */
> + hostfs_dev_path = blkid_devno_to_devname(st.st_dev);
> + if (hostfs_dev_path) {
> + fd = open(hostfs_dev_path, O_RDONLY);
> + if (fd >= 0)
> + if (ioctl(fd, BLKSSZGET, bsz) < 0)
> + *bsz = BBSIZE;
> + close(fd);
> + free(hostfs_dev_path);
> + }
So the current behaviour is to use the underlying filesystem
sector size, but we might have a 4k fs sector on a 512 physical
sector device, and you want to detect this, right? The logical
sector size is exposed by the filesystem in the XFS_IOC_DIOINFO
information. i.e:
case XFS_IOC_DIOINFO: {
struct dioattr da;
xfs_buftarg_t *target =
XFS_IS_REALTIME_INODE(ip) ?
mp->m_rtdev_targp : mp->m_ddev_targp;
da.d_mem = da.d_miniosz = target->bt_logical_sectorsize;
da.d_maxiosz = INT_MAX & ~(da.d_miniosz - 1);
if (copy_to_user(arg, &da, sizeof(da)))
return -EFAULT;
return 0;
}
Isn't this exactly what XFS_IOC_DIOINFO is for?
(Oh, and "old kernels don't support...." simply means the distros
will have a kernel patch to backport, too....)
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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