Created attachment 219540 [details] convert 32 bit zfs_iocparm_t to 64 bit When 32 bit applications use libzfs to access ZFS data, they always fail in zfs_open(), with 32 bit "zfs list" and "zpool list" crashing. This is because /usr/src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c function zfsdev_ioctl() checks for: ---snip--- if (len != sizeof(zfs_iocparm_t)) { ---snip--- On amd64, sizeof(zfs_iocparm_t) is 24, as in /usr/src/sys/cddl/contrib/opensolaris/common/zfs/zfs_ioctl_compat.h we have: ---snip--- typedef struct zfs_iocparm { uint32_t zfs_ioctl_version; uint64_t zfs_cmd; uint64_t zfs_cmd_size; } zfs_iocparm_t; ---snip--- which has its fields aligned to 8 byte boundaries. On i386, they are aligned to 4 byte boundaries, sizeof(zfs_iocparm_t) is only 20, and every ioctl fails with EINVAL. This affects Wine as it runs many 32 bit apps. Since Windows is case-insensitive, Wine has to slowly scan the entire directory when doing file I/O on a case-sensitive filesystem, to match filenames case-insensitively. ZFS can create filesystems with casesensitivity=insensitive, allowing Wine to skip the slow scan and speeding up file I/O considerably for some apps. When developing a patch to Wine to check that casesensitivity property and use it when insensitive (https://source.winehq.org/patches/data/195726) I noticed zfs_open() always fails, which led me to this bug. The attached patch correctly converts the 32 bit zfs_iocparm_t to 64 bit, and allows at least Wine to work correctly. I haven't yet had a chance to test whether it fixes 32 bit versions of the "zpool" and "zfs" tools (which probably use more elaborate ioctls).
zfs-devel@ is disused.
With further tests, I see that 32 bit "zpool" and "zfs" commands go from crashing to fully working with this patch. I can successfully zpool create, zpool destroy, zpool list, zpool status, zfs list, zfs create, zfs get all, etc.