The WRITE_FLUSH, WRITE_FUA, and WRITE_FLUSH_FUA flags have been
introduced as a replacement for WRITE_BARRIER. This was done
to allow richer semantics to be expressed to the block layer.
It is the block layers responsibility to choose the correct way
to implement these semantics.
This change simply updates the bio's to use the new kernel API
which should be absolutely safe. However, since ZFS depends
entirely on this working as designed for correctness we do
want to be careful.
Closes#281
The blk_queue_stackable() queue flag was added in 2.6.27 to handle dm
stacking drivers. Prior to this request stacking drivers were detected
by checking (q->request_fn == NULL), for earlier kernels we revert to
this legacy behavior.
The open_bdev_exclusive() function has been replaced (again) by the
more generic blkdev_get_by_path() function. Additionally, the
counterpart function close_bdev_exclusive() has been replaced by
blkdev_put(). Because these functions are more generic versions
of the functions they replaced the compatibility macro must add
the FMODE_EXCL mask to ensure they are exclusive.
Closes#114
For legacy reasons the zvol.c and vdev_disk.c Linux compatibility
code ended up in sys/blkdev.h and sys/vdev_disk.h headers. While
there are worse places for this code to live it should be in a
linux/blkdev_compat.h header. This change moves this block device
Linux compatibility code in to the linux/blkdev_compat.h header
and updates all the correct #include locations. This is not a
functional change or bug fix, it is just code cleanup.
