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Linux 4.8 compat: Fix removal of bio->bi_rw member
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All users of bio->bi_rw have been replaced with compatibility wrappers.
This allows the kernel specific logic to be abstracted away, and for
each of the supported cases to be documented with the wrapper.  The
updated interfaces are as follows:

* void blk_queue_set_write_cache(struct request_queue *, bool, bool)
* boolean_t bio_is_flush(struct bio *)
* boolean_t bio_is_fua(struct bio *)
* boolean_t bio_is_discard(struct bio *)
* boolean_t bio_is_secure_erase(struct bio *)
* VDEV_WRITE_FLUSH_FUA

Signed-off-by: Brian Behlendorf <[email protected]>
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behlendorf committed Aug 10, 2016
1 parent 52af1f6 commit 26938f3
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Showing 4 changed files with 190 additions and 77 deletions.
67 changes: 67 additions & 0 deletions config/kernel-bio-op.m4
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,67 @@
dnl #
dnl # Linux 4.8 API,
dnl #
dnl # The bio_op() helper was introduced as a replacement for explicitly
dnl # checking the bio->bi_rw flags. The following checks are used to
dnl # detect if a specific operation is supported.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_REQ_OP_DISCARD], [
AC_MSG_CHECKING([whether REQ_OP_DISCARD is defined])
ZFS_LINUX_TRY_COMPILE([
#include <linux/blk_types.h>
],[
enum req_op op __attribute__ ((unused)) = REQ_OP_DISCARD;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_REQ_OP_DISCARD, 1,
[REQ_OP_DISCARD is defined])
],[
AC_MSG_RESULT(no)
])
])

AC_DEFUN([ZFS_AC_KERNEL_REQ_OP_SECURE_ERASE], [
AC_MSG_CHECKING([whether REQ_OP_SECURE_ERASE is defined])
ZFS_LINUX_TRY_COMPILE([
#include <linux/blk_types.h>
],[
enum req_op op __attribute__ ((unused)) = REQ_OP_SECURE_ERASE;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_REQ_OP_SECURE_DISCARD, 1,
[REQ_OP_SECURE_ERASE is defined])
],[
AC_MSG_RESULT(no)
])
])


AC_DEFUN([ZFS_AC_KERNEL_REQ_OP_FLUSH], [
AC_MSG_CHECKING([whether REQ_OP_FLUSH is defined])
ZFS_LINUX_TRY_COMPILE([
#include <linux/blk_types.h>
],[
enum req_op op __attribute__ ((unused)) = REQ_OP_FLUSH;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_REQ_OP_FLUSH, 1,
[REQ_OP_FLUSH is defined])
],[
AC_MSG_RESULT(no)
])
])

AC_DEFUN([ZFS_AC_KERNEL_BIO_BI_OPF], [
AC_MSG_CHECKING([whether bio->bi_opf is defined])
ZFS_LINUX_TRY_COMPILE([
#include <linux/bio.h>
],[
struct bio bio __attribute__ ((unused));
bio.bi_opf = 0;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_BIO_BI_OPF, 1, [bio->bi_opf is defined])
],[
AC_MSG_RESULT(no)
])
])
4 changes: 4 additions & 0 deletions config/kernel.m4
View file
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,10 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
ZFS_AC_KERNEL_BIO_BVEC_ITER
ZFS_AC_KERNEL_BIO_FAILFAST_DTD
ZFS_AC_KERNEL_REQ_FAILFAST_MASK
ZFS_AC_KERNEL_REQ_OP_DISCARD
ZFS_AC_KERNEL_REQ_OP_SECURE_ERASE
ZFS_AC_KERNEL_REQ_OP_FLUSH
ZFS_AC_KERNEL_BIO_BI_OPF
ZFS_AC_KERNEL_BIO_END_IO_T_ARGS
ZFS_AC_KERNEL_BIO_RW_BARRIER
ZFS_AC_KERNEL_BIO_RW_DISCARD
Expand Down
165 changes: 109 additions & 56 deletions include/linux/blkdev_compat.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -37,35 +37,24 @@ typedef unsigned __bitwise__ fmode_t;
#endif /* HAVE_FMODE_T */

/*
* 2.6.36 API change,
* 4.7 - 4.x API,
* The blk_queue_write_cache() interface has replaced blk_queue_flush()
* interface. However, the new interface is GPL-only thus we implement
* our own trivial wrapper when the GPL-only version is detected.
*
* 2.6.36 - 4.6 API,
* The blk_queue_flush() interface has replaced blk_queue_ordered()
* interface. However, while the old interface was available to all the
* new one is GPL-only. Thus if the GPL-only version is detected we
* implement our own trivial helper compatibility funcion. The hope is
* that long term this function will be opened up.
*/
#if defined(HAVE_BLK_QUEUE_FLUSH) && defined(HAVE_BLK_QUEUE_FLUSH_GPL_ONLY)
#define blk_queue_flush __blk_queue_flush
static inline void
__blk_queue_flush(struct request_queue *q, unsigned int flags)
{
q->flush_flags = flags & (REQ_FLUSH | REQ_FUA);
}
#endif /* HAVE_BLK_QUEUE_FLUSH && HAVE_BLK_QUEUE_FLUSH_GPL_ONLY */

/*
* 4.7 API change,
* The blk_queue_write_cache() interface has replaced blk_queue_flush()
* interface. However, while the new interface is GPL-only. Thus if the
* GPL-only version is detected we implement our own trivial helper
* compatibility funcion.
* implement our own trivial helper.
*
* 2.6.x - 2.6.35
* Legacy blk_queue_ordered() interface.
*/
#if defined(HAVE_BLK_QUEUE_WRITE_CACHE) && \
defined(HAVE_BLK_QUEUE_WRITE_CACHE_GPL_ONLY)
#define blk_queue_write_cache __blk_queue_write_cache
static inline void
__blk_queue_write_cache(struct request_queue *q, bool wc, bool fua)
blk_queue_set_write_cache(struct request_queue *q, bool wc, bool fua)
{
#if defined(HAVE_BLK_QUEUE_WRITE_CACHE_GPL_ONLY)
spin_lock_irq(q->queue_lock);
if (wc)
queue_flag_set(QUEUE_FLAG_WC, q);
Expand All @@ -76,8 +65,19 @@ __blk_queue_write_cache(struct request_queue *q, bool wc, bool fua)
else
queue_flag_clear(QUEUE_FLAG_FUA, q);
spin_unlock_irq(q->queue_lock);
}
#elif defined(HAVE_BLK_QUEUE_WRITE_CACHE)
blk_queue_write_cache(q, wc, fua);
#elif defined(HAVE_BLK_QUEUE_FLUSH_GPL_ONLY)
if (wc)
q->flush_flags |= REQ_FLUSH;
if (fua)
q->flush_flags |= REQ_FUA;
#elif defined(HAVE_BLK_QUEUE_FLUSH)
blk_queue_flush(q, (wc ? REQ_FLUSH : 0) | (fua ? REQ_FUA : 0));
#else
blk_queue_ordered(q, QUEUE_ORDERED_DRAIN, NULL);
#endif
}

/*
* Most of the blk_* macros were removed in 2.6.36. Ostensibly this was
Expand Down Expand Up @@ -301,68 +301,121 @@ bio_set_flags_failfast(struct block_device *bdev, int *flags)
* 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.
*
* The existence of these flags implies that REQ_FLUSH an REQ_FUA are
* defined. Thus we can safely define VDEV_REQ_FLUSH and VDEV_REQ_FUA
* compatibility macros.
*
* Linux 4.8 renamed the REQ_FLUSH to REQ_PREFLUSH but there was no
* functional change in behavior.
*/
#ifdef WRITE_FLUSH_FUA

#define VDEV_WRITE_FLUSH_FUA WRITE_FLUSH_FUA
#ifdef REQ_PREFLUSH
#define VDEV_REQ_FLUSH REQ_PREFLUSH
#define VDEV_REQ_FUA REQ_FUA
#else
#define VDEV_REQ_FLUSH REQ_FLUSH
#define VDEV_REQ_FUA REQ_FUA
#define VDEV_WRITE_FLUSH_FUA WRITE_BARRIER
#endif

/*
* 4.8 - 4.x API,
* REQ_OP_FLUSH
*
* 4.8-rc0 - 4.8-rc1,
* REQ_PREFLUSH
*
* 2.6.36 - 4.7 API,
* REQ_FLUSH
*
* 2.6.x - 2.6.35 API,
* HAVE_BIO_RW_BARRIER
*
* Used to determine if a cache flush has been requested. This check has
* been left intentionally broad in order to cover both a legacy flush
* and the new preflush behavior introduced in Linux 4.8. This is correct
* in all cases but may have a performance impact for some kernels. It
* has the advantage of minimizing kernel specific changes in the zvol code.
*/
static inline boolean_t
bio_is_flush(struct bio *bio)
{
#if defined(HAVE_REQ_OP_FLUSH) && defined(HAVE_BIO_BI_OPF)
return ((bio_op(bio) == REQ_OP_FLUSH) || (bio->bi_opf & REQ_PREFLUSH));
#elif defined(REQ_PREFLUSH) && defined(HAVE_BIO_BI_OPF)
return (bio->bi_opf & REQ_PREFLUSH);
#elif defined(REQ_PREFLUSH) && !defined(HAVE_BIO_BI_OPF)
return (bio->bi_rw & REQ_PREFLUSH);
#elif defined(REQ_FLUSH)
return (bio->bi_rw & REQ_FLUSH);
#elif defined(HAVE_BIO_RW_BARRIER)
return (bio->bi_rw & (1 << BIO_RW_BARRIER));
#else

#define VDEV_WRITE_FLUSH_FUA WRITE_BARRIER
#ifdef HAVE_BIO_RW_BARRIER
#define VDEV_REQ_FLUSH (1 << BIO_RW_BARRIER)
#define VDEV_REQ_FUA (1 << BIO_RW_BARRIER)
#else
#define VDEV_REQ_FLUSH REQ_HARDBARRIER
#define VDEV_REQ_FUA REQ_FUA
#error "Allowing the build will cause flush requests to be ignored. Please "
"file an issue report at: https://github.com/zfsonlinux/zfs/issues/new"
#endif
}

/*
* 4.8 - 4.x API,
* REQ_FUA flag moved to bio->bi_opf
*
* 2.6.x - 4.7 API,
* REQ_FUA
*/
static inline boolean_t
bio_is_fua(struct bio *bio)
{
#if defined(HAVE_BIO_BI_OPF)
return (bio->bi_opf & REQ_FUA);
#elif defined(REQ_FUA)
return (bio->bi_rw & REQ_FUA);
#else
#error "Allowing the build will cause fua requests to be ignored. Please "
"file an issue report at: https://github.com/zfsonlinux/zfs/issues/new"
#endif
}

/*
* 2.6.28 - 2.6.35 API,
* BIO_RW_DISCARD
* 4.8 - 4.x API,
* REQ_OP_DISCARD
*
* 2.6.36 - 4.7 API,
* REQ_DISCARD
*
* 4.8 - 4.x API,
* REQ_OP_DISCARD
* 2.6.28 - 2.6.35 API,
* BIO_RW_DISCARD
*
* In all cases the normal I/O path is used for discards. The only
* difference is how the kernel tags individual I/Os as discards.
*/
#ifdef QUEUE_FLAG_DISCARD
static inline boolean_t
bio_is_discard(struct bio *bio)
{
#if defined(HAVE_BIO_RW_DISCARD)
return (bio->bi_rw & (1 << BIO_RW_DISCARD));
#if defined(HAVE_REQ_OP_DISCARD)
return (bio_op(bio) == REQ_OP_DISCARD);
#elif defined(REQ_DISCARD)
return (bio->bi_rw & REQ_DISCARD);
#elif defined(HAVE_BIO_RW_DISCARD)
return (bio->bi_rw & (1 << BIO_RW_DISCARD));
#else
return (bio_op(bio) == REQ_OP_DISCARD);
#error "Allowing the build will cause discard requests to become writes "
"potentially triggering the DMU_MAX_ACCESS assertion. Please file "
"an issue report at: https://github.com/zfsonlinux/zfs/issues/new"
#endif
}

/*
* 4.8 - 4.x API,
* REQ_OP_SECURE_ERASE
*
* 2.6.36 - 4.7 API,
* REQ_SECURE
*
* 2.6.x - 2.6.35 API,
* Unsupported by kernel
*/
static inline boolean_t
bio_is_secure_erase(struct bio *bio)
{
#if defined(HAVE_REQ_OP_SECURE_ERASE)
return (bio_op(bio) == REQ_OP_SECURE_ERASE);
#elif defined(REQ_SECURE)
return (bio->bi_rw & REQ_SECURE);
#else
#error "Allowing the build will cause discard requests to become writes "
"potentially triggering the DMU_MAX_ACCESS assertion. Please file a "
"an issue report at: https://github.com/zfsonlinux/zfs/issues/new"
return (0);
#endif
}

/*
* 2.6.33 API change
Expand Down
31 changes: 10 additions & 21 deletions module/zfs/zvol.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -707,20 +707,16 @@ zvol_discard(struct bio *bio)
return (SET_ERROR(EIO));

/*
* Align the request to volume block boundaries when REQ_SECURE is
* available, but not requested. If we don't, then this will force
* dnode_free_range() to zero out the unaligned parts, which is slow
* (read-modify-write) and useless since we are not freeing any space
* by doing so. Kernels that do not support REQ_SECURE (2.6.32 through
* 2.6.35) will not receive this optimization.
* Align the request to volume block boundaries when a secure erase is
* not required. This will prevent dnode_free_range() from zeroing out
* the unaligned parts which is slow (read-modify-write) and useless
* since we are not freeing any space by doing so.
*/
#ifdef REQ_SECURE
if (!(bio->bi_rw & REQ_SECURE)) {
if (!bio_is_secure_erase(bio)) {
start = P2ROUNDUP(start, zv->zv_volblocksize);
end = P2ALIGN(end, zv->zv_volblocksize);
size = end - start;
}
#endif

if (start >= end)
return (0);
Expand Down Expand Up @@ -812,7 +808,7 @@ zvol_request(struct request_queue *q, struct bio *bio)
goto out2;
}

if (bio_is_discard(bio)) {
if (bio_is_discard(bio) || bio_is_secure_erase(bio)) {
error = zvol_discard(bio);
goto out2;
}
Expand All @@ -821,14 +817,14 @@ zvol_request(struct request_queue *q, struct bio *bio)
* Some requests are just for flush and nothing else.
*/
if (uio.uio_resid == 0) {
if (bio->bi_rw & VDEV_REQ_FLUSH)
if (bio_is_flush(bio))
zil_commit(zv->zv_zilog, ZVOL_OBJ);
goto out2;
}

error = zvol_write(zv, &uio,
((bio->bi_rw & (VDEV_REQ_FUA|VDEV_REQ_FLUSH)) ||
zv->zv_objset->os_sync == ZFS_SYNC_ALWAYS));
bio_is_flush(bio) || bio_is_fua(bio) ||
zv->zv_objset->os_sync == ZFS_SYNC_ALWAYS);
} else
error = zvol_read(zv, &uio);

Expand Down Expand Up @@ -1290,14 +1286,7 @@ zvol_alloc(dev_t dev, const char *name)
goto out_kmem;

blk_queue_make_request(zv->zv_queue, zvol_request);

#ifdef HAVE_BLK_QUEUE_WRITE_CACHE
blk_queue_write_cache(zv->zv_queue, B_TRUE, B_TRUE);
#elif defined(HAVE_BLK_QUEUE_FLUSH)
blk_queue_flush(zv->zv_queue, VDEV_REQ_FLUSH | VDEV_REQ_FUA);
#else
blk_queue_ordered(zv->zv_queue, QUEUE_ORDERED_DRAIN, NULL);
#endif /* HAVE_BLK_QUEUE_FLUSH */
blk_queue_set_write_cache(zv->zv_queue, B_TRUE, B_TRUE);

zv->zv_disk = alloc_disk(ZVOL_MINORS);
if (zv->zv_disk == NULL)
Expand Down

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