On Tue, 11 Jun 2024 at 07:24, Christoph Hellwig <hch@xxxxxx> wrote:
>
> Move the cache control settings into the queue_limits so that they
> can be set atomically and all I/O is frozen when changing the
> flags.
>
> Add new features and flags field for the driver set flags, and internal
> (usually sysfs-controlled) flags in the block layer. Note that we'll
> eventually remove enough field from queue_limits to bring it back to the
> previous size.
>
> The disable flag is inverted compared to the previous meaning, which
> means it now survives a rescan, similar to the max_sectors and
> max_discard_sectors user limits.
>
> The FLUSH and FUA flags are now inherited by blk_stack_limits, which
> simplified the code in dm a lot, but also causes a slight behavior
> change in that dm-switch and dm-unstripe now advertise a write cache
> despite setting num_flush_bios to 0. The I/O path will handle this
> gracefully, but as far as I can tell the lack of num_flush_bios
> and thus flush support is a pre-existing data integrity bug in those
> targets that really needs fixing, after which a non-zero num_flush_bios
> should be required in dm for targets that map to underlying devices.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Acked-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> # For MMC
FYI, for now I don't expect any other patches in my mmc tree to clash
with this for v6.11, assuming that is the target.
Kind regards
Uffe
> ---
> .../block/writeback_cache_control.rst | 67 +++++++++++--------
> arch/um/drivers/ubd_kern.c | 2 +-
> block/blk-core.c | 2 +-
> block/blk-flush.c | 9 ++-
> block/blk-mq-debugfs.c | 2 -
> block/blk-settings.c | 29 ++------
> block/blk-sysfs.c | 29 +++++---
> block/blk-wbt.c | 4 +-
> drivers/block/drbd/drbd_main.c | 2 +-
> drivers/block/loop.c | 9 +--
> drivers/block/nbd.c | 14 ++--
> drivers/block/null_blk/main.c | 12 ++--
> drivers/block/ps3disk.c | 7 +-
> drivers/block/rnbd/rnbd-clt.c | 10 +--
> drivers/block/ublk_drv.c | 8 ++-
> drivers/block/virtio_blk.c | 20 ++++--
> drivers/block/xen-blkfront.c | 9 ++-
> drivers/md/bcache/super.c | 7 +-
> drivers/md/dm-table.c | 39 +++--------
> drivers/md/md.c | 8 ++-
> drivers/mmc/core/block.c | 42 ++++++------
> drivers/mmc/core/queue.c | 12 ++--
> drivers/mmc/core/queue.h | 3 +-
> drivers/mtd/mtd_blkdevs.c | 5 +-
> drivers/nvdimm/pmem.c | 4 +-
> drivers/nvme/host/core.c | 7 +-
> drivers/nvme/host/multipath.c | 6 --
> drivers/scsi/sd.c | 28 +++++---
> include/linux/blkdev.h | 38 +++++++++--
> 29 files changed, 227 insertions(+), 207 deletions(-)
>
> diff --git a/Documentation/block/writeback_cache_control.rst b/Documentation/block/writeback_cache_control.rst
> index b208488d0aae85..9cfe27f90253c7 100644
> --- a/Documentation/block/writeback_cache_control.rst
> +++ b/Documentation/block/writeback_cache_control.rst
> @@ -46,41 +46,50 @@ worry if the underlying devices need any explicit cache flushing and how
> the Forced Unit Access is implemented. The REQ_PREFLUSH and REQ_FUA flags
> may both be set on a single bio.
>
> +Feature settings for block drivers
> +----------------------------------
>
> -Implementation details for bio based block drivers
> ---------------------------------------------------------------
> +For devices that do not support volatile write caches there is no driver
> +support required, the block layer completes empty REQ_PREFLUSH requests before
> +entering the driver and strips off the REQ_PREFLUSH and REQ_FUA bits from
> +requests that have a payload.
>
> -These drivers will always see the REQ_PREFLUSH and REQ_FUA bits as they sit
> -directly below the submit_bio interface. For remapping drivers the REQ_FUA
> -bits need to be propagated to underlying devices, and a global flush needs
> -to be implemented for bios with the REQ_PREFLUSH bit set. For real device
> -drivers that do not have a volatile cache the REQ_PREFLUSH and REQ_FUA bits
> -on non-empty bios can simply be ignored, and REQ_PREFLUSH requests without
> -data can be completed successfully without doing any work. Drivers for
> -devices with volatile caches need to implement the support for these
> -flags themselves without any help from the block layer.
> +For devices with volatile write caches the driver needs to tell the block layer
> +that it supports flushing caches by setting the
>
> + BLK_FEAT_WRITE_CACHE
>
> -Implementation details for request_fn based block drivers
> ----------------------------------------------------------
> +flag in the queue_limits feature field. For devices that also support the FUA
> +bit the block layer needs to be told to pass on the REQ_FUA bit by also setting
> +the
>
> -For devices that do not support volatile write caches there is no driver
> -support required, the block layer completes empty REQ_PREFLUSH requests before
> -entering the driver and strips off the REQ_PREFLUSH and REQ_FUA bits from
> -requests that have a payload. For devices with volatile write caches the
> -driver needs to tell the block layer that it supports flushing caches by
> -doing::
> + BLK_FEAT_FUA
> +
> +flag in the features field of the queue_limits structure.
> +
> +Implementation details for bio based block drivers
> +--------------------------------------------------
> +
> +For bio based drivers the REQ_PREFLUSH and REQ_FUA bit are simplify passed on
> +to the driver if the drivers sets the BLK_FEAT_WRITE_CACHE flag and the drivers
> +needs to handle them.
> +
> +*NOTE*: The REQ_FUA bit also gets passed on when the BLK_FEAT_FUA flags is
> +_not_ set. Any bio based driver that sets BLK_FEAT_WRITE_CACHE also needs to
> +handle REQ_FUA.
>
> - blk_queue_write_cache(sdkp->disk->queue, true, false);
> +For remapping drivers the REQ_FUA bits need to be propagated to underlying
> +devices, and a global flush needs to be implemented for bios with the
> +REQ_PREFLUSH bit set.
>
> -and handle empty REQ_OP_FLUSH requests in its prep_fn/request_fn. Note that
> -REQ_PREFLUSH requests with a payload are automatically turned into a sequence
> -of an empty REQ_OP_FLUSH request followed by the actual write by the block
> -layer. For devices that also support the FUA bit the block layer needs
> -to be told to pass through the REQ_FUA bit using::
> +Implementation details for blk-mq drivers
> +-----------------------------------------
>
> - blk_queue_write_cache(sdkp->disk->queue, true, true);
> +When the BLK_FEAT_WRITE_CACHE flag is set, REQ_OP_WRITE | REQ_PREFLUSH requests
> +with a payload are automatically turned into a sequence of a REQ_OP_FLUSH
> +request followed by the actual write by the block layer.
>
> -and the driver must handle write requests that have the REQ_FUA bit set
> -in prep_fn/request_fn. If the FUA bit is not natively supported the block
> -layer turns it into an empty REQ_OP_FLUSH request after the actual write.
> +When the BLK_FEA_FUA flags is set, the REQ_FUA bit simplify passed on for the
> +REQ_OP_WRITE request, else a REQ_OP_FLUSH request is sent by the block layer
> +after the completion of the write request for bio submissions with the REQ_FUA
> +bit set.
> diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
> index cdcb75a68989dd..19e01691ea0ea7 100644
> --- a/arch/um/drivers/ubd_kern.c
> +++ b/arch/um/drivers/ubd_kern.c
> @@ -835,6 +835,7 @@ static int ubd_add(int n, char **error_out)
> struct queue_limits lim = {
> .max_segments = MAX_SG,
> .seg_boundary_mask = PAGE_SIZE - 1,
> + .features = BLK_FEAT_WRITE_CACHE,
> };
> struct gendisk *disk;
> int err = 0;
> @@ -882,7 +883,6 @@ static int ubd_add(int n, char **error_out)
> }
>
> blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
> - blk_queue_write_cache(disk->queue, true, false);
> disk->major = UBD_MAJOR;
> disk->first_minor = n << UBD_SHIFT;
> disk->minors = 1 << UBD_SHIFT;
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 82c3ae22d76d88..2b45a4df9a1aa1 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -782,7 +782,7 @@ void submit_bio_noacct(struct bio *bio)
> if (WARN_ON_ONCE(bio_op(bio) != REQ_OP_WRITE &&
> bio_op(bio) != REQ_OP_ZONE_APPEND))
> goto end_io;
> - if (!test_bit(QUEUE_FLAG_WC, &q->queue_flags)) {
> + if (!bdev_write_cache(bdev)) {
> bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA);
> if (!bio_sectors(bio)) {
> status = BLK_STS_OK;
> diff --git a/block/blk-flush.c b/block/blk-flush.c
> index 2234f8b3fc05f2..30b9d5033a2b85 100644
> --- a/block/blk-flush.c
> +++ b/block/blk-flush.c
> @@ -381,8 +381,8 @@ static void blk_rq_init_flush(struct request *rq)
> bool blk_insert_flush(struct request *rq)
> {
> struct request_queue *q = rq->q;
> - unsigned long fflags = q->queue_flags; /* may change, cache */
> struct blk_flush_queue *fq = blk_get_flush_queue(q, rq->mq_ctx);
> + bool supports_fua = q->limits.features & BLK_FEAT_FUA;
> unsigned int policy = 0;
>
> /* FLUSH/FUA request must never be merged */
> @@ -394,11 +394,10 @@ bool blk_insert_flush(struct request *rq)
> /*
> * Check which flushes we need to sequence for this operation.
> */
> - if (fflags & (1UL << QUEUE_FLAG_WC)) {
> + if (blk_queue_write_cache(q)) {
> if (rq->cmd_flags & REQ_PREFLUSH)
> policy |= REQ_FSEQ_PREFLUSH;
> - if (!(fflags & (1UL << QUEUE_FLAG_FUA)) &&
> - (rq->cmd_flags & REQ_FUA))
> + if ((rq->cmd_flags & REQ_FUA) && !supports_fua)
> policy |= REQ_FSEQ_POSTFLUSH;
> }
>
> @@ -407,7 +406,7 @@ bool blk_insert_flush(struct request *rq)
> * REQ_PREFLUSH and FUA for the driver.
> */
> rq->cmd_flags &= ~REQ_PREFLUSH;
> - if (!(fflags & (1UL << QUEUE_FLAG_FUA)))
> + if (!supports_fua)
> rq->cmd_flags &= ~REQ_FUA;
>
> /*
> diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
> index 770c0c2b72faaa..e8b9db7c30c455 100644
> --- a/block/blk-mq-debugfs.c
> +++ b/block/blk-mq-debugfs.c
> @@ -93,8 +93,6 @@ static const char *const blk_queue_flag_name[] = {
> QUEUE_FLAG_NAME(INIT_DONE),
> QUEUE_FLAG_NAME(STABLE_WRITES),
> QUEUE_FLAG_NAME(POLL),
> - QUEUE_FLAG_NAME(WC),
> - QUEUE_FLAG_NAME(FUA),
> QUEUE_FLAG_NAME(DAX),
> QUEUE_FLAG_NAME(STATS),
> QUEUE_FLAG_NAME(REGISTERED),
> diff --git a/block/blk-settings.c b/block/blk-settings.c
> index f11c8676eb4c67..536ee202fcdccb 100644
> --- a/block/blk-settings.c
> +++ b/block/blk-settings.c
> @@ -261,6 +261,9 @@ static int blk_validate_limits(struct queue_limits *lim)
> lim->misaligned = 0;
> }
>
> + if (!(lim->features & BLK_FEAT_WRITE_CACHE))
> + lim->features &= ~BLK_FEAT_FUA;
> +
> err = blk_validate_integrity_limits(lim);
> if (err)
> return err;
> @@ -454,6 +457,8 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
> {
> unsigned int top, bottom, alignment, ret = 0;
>
> + t->features |= (b->features & BLK_FEAT_INHERIT_MASK);
> +
> t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
> t->max_user_sectors = min_not_zero(t->max_user_sectors,
> b->max_user_sectors);
> @@ -711,30 +716,6 @@ void blk_set_queue_depth(struct request_queue *q, unsigned int depth)
> }
> EXPORT_SYMBOL(blk_set_queue_depth);
>
> -/**
> - * blk_queue_write_cache - configure queue's write cache
> - * @q: the request queue for the device
> - * @wc: write back cache on or off
> - * @fua: device supports FUA writes, if true
> - *
> - * Tell the block layer about the write cache of @q.
> - */
> -void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua)
> -{
> - if (wc) {
> - blk_queue_flag_set(QUEUE_FLAG_HW_WC, q);
> - blk_queue_flag_set(QUEUE_FLAG_WC, q);
> - } else {
> - blk_queue_flag_clear(QUEUE_FLAG_HW_WC, q);
> - blk_queue_flag_clear(QUEUE_FLAG_WC, q);
> - }
> - if (fua)
> - blk_queue_flag_set(QUEUE_FLAG_FUA, q);
> - else
> - blk_queue_flag_clear(QUEUE_FLAG_FUA, q);
> -}
> -EXPORT_SYMBOL_GPL(blk_queue_write_cache);
> -
> int bdev_alignment_offset(struct block_device *bdev)
> {
> struct request_queue *q = bdev_get_queue(bdev);
> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
> index 5c787965b7d09e..4f524c1d5e08bd 100644
> --- a/block/blk-sysfs.c
> +++ b/block/blk-sysfs.c
> @@ -423,32 +423,41 @@ static ssize_t queue_io_timeout_store(struct request_queue *q, const char *page,
>
> static ssize_t queue_wc_show(struct request_queue *q, char *page)
> {
> - if (test_bit(QUEUE_FLAG_WC, &q->queue_flags))
> - return sprintf(page, "write back\n");
> -
> - return sprintf(page, "write through\n");
> + if (q->limits.features & BLK_FLAGS_WRITE_CACHE_DISABLED)
> + return sprintf(page, "write through\n");
> + return sprintf(page, "write back\n");
> }
>
> static ssize_t queue_wc_store(struct request_queue *q, const char *page,
> size_t count)
> {
> + struct queue_limits lim;
> + bool disable;
> + int err;
> +
> if (!strncmp(page, "write back", 10)) {
> - if (!test_bit(QUEUE_FLAG_HW_WC, &q->queue_flags))
> - return -EINVAL;
> - blk_queue_flag_set(QUEUE_FLAG_WC, q);
> + disable = false;
> } else if (!strncmp(page, "write through", 13) ||
> - !strncmp(page, "none", 4)) {
> - blk_queue_flag_clear(QUEUE_FLAG_WC, q);
> + !strncmp(page, "none", 4)) {
> + disable = true;
> } else {
> return -EINVAL;
> }
>
> + lim = queue_limits_start_update(q);
> + if (disable)
> + lim.flags |= BLK_FLAGS_WRITE_CACHE_DISABLED;
> + else
> + lim.flags &= ~BLK_FLAGS_WRITE_CACHE_DISABLED;
> + err = queue_limits_commit_update(q, &lim);
> + if (err)
> + return err;
> return count;
> }
>
> static ssize_t queue_fua_show(struct request_queue *q, char *page)
> {
> - return sprintf(page, "%u\n", test_bit(QUEUE_FLAG_FUA, &q->queue_flags));
> + return sprintf(page, "%u\n", !!(q->limits.features & BLK_FEAT_FUA));
> }
>
> static ssize_t queue_dax_show(struct request_queue *q, char *page)
> diff --git a/block/blk-wbt.c b/block/blk-wbt.c
> index 64472134dd26df..1a5e4b049ecd1d 100644
> --- a/block/blk-wbt.c
> +++ b/block/blk-wbt.c
> @@ -206,8 +206,8 @@ static void wbt_rqw_done(struct rq_wb *rwb, struct rq_wait *rqw,
> */
> if (wb_acct & WBT_DISCARD)
> limit = rwb->wb_background;
> - else if (test_bit(QUEUE_FLAG_WC, &rwb->rqos.disk->queue->queue_flags) &&
> - !wb_recent_wait(rwb))
> + else if (blk_queue_write_cache(rwb->rqos.disk->queue) &&
> + !wb_recent_wait(rwb))
> limit = 0;
> else
> limit = rwb->wb_normal;
> diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
> index 113b441d4d3670..bf42a46781fa21 100644
> --- a/drivers/block/drbd/drbd_main.c
> +++ b/drivers/block/drbd/drbd_main.c
> @@ -2697,6 +2697,7 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig
> * connect.
> */
> .max_hw_sectors = DRBD_MAX_BIO_SIZE_SAFE >> 8,
> + .features = BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA,
> };
>
> device = minor_to_device(minor);
> @@ -2736,7 +2737,6 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig
> disk->private_data = device;
>
> blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, disk->queue);
> - blk_queue_write_cache(disk->queue, true, true);
>
> device->md_io.page = alloc_page(GFP_KERNEL);
> if (!device->md_io.page)
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index 2c4a5eb3a6a7f9..0b23fdc4e2edcc 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -985,6 +985,9 @@ static int loop_reconfigure_limits(struct loop_device *lo, unsigned short bsize)
> lim.logical_block_size = bsize;
> lim.physical_block_size = bsize;
> lim.io_min = bsize;
> + lim.features &= ~BLK_FEAT_WRITE_CACHE;
> + if (file->f_op->fsync && !(lo->lo_flags & LO_FLAGS_READ_ONLY))
> + lim.features |= BLK_FEAT_WRITE_CACHE;
> if (!backing_bdev || bdev_nonrot(backing_bdev))
> blk_queue_flag_set(QUEUE_FLAG_NONROT, lo->lo_queue);
> else
> @@ -1078,9 +1081,6 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode,
> lo->old_gfp_mask = mapping_gfp_mask(mapping);
> mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
>
> - if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
> - blk_queue_write_cache(lo->lo_queue, true, false);
> -
> error = loop_reconfigure_limits(lo, config->block_size);
> if (WARN_ON_ONCE(error))
> goto out_unlock;
> @@ -1131,9 +1131,6 @@ static void __loop_clr_fd(struct loop_device *lo, bool release)
> struct file *filp;
> gfp_t gfp = lo->old_gfp_mask;
>
> - if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags))
> - blk_queue_write_cache(lo->lo_queue, false, false);
> -
> /*
> * Freeze the request queue when unbinding on a live file descriptor and
> * thus an open device. When called from ->release we are guaranteed
> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> index 44b8c671921e5c..cb1c86a6a3fb9d 100644
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -342,12 +342,14 @@ static int __nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
> lim.max_hw_discard_sectors = UINT_MAX;
> else
> lim.max_hw_discard_sectors = 0;
> - if (!(nbd->config->flags & NBD_FLAG_SEND_FLUSH))
> - blk_queue_write_cache(nbd->disk->queue, false, false);
> - else if (nbd->config->flags & NBD_FLAG_SEND_FUA)
> - blk_queue_write_cache(nbd->disk->queue, true, true);
> - else
> - blk_queue_write_cache(nbd->disk->queue, true, false);
> + if (!(nbd->config->flags & NBD_FLAG_SEND_FLUSH)) {
> + lim.features &= ~(BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA);
> + } else if (nbd->config->flags & NBD_FLAG_SEND_FUA) {
> + lim.features |= BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA;
> + } else {
> + lim.features |= BLK_FEAT_WRITE_CACHE;
> + lim.features &= ~BLK_FEAT_FUA;
> + }
> lim.logical_block_size = blksize;
> lim.physical_block_size = blksize;
> error = queue_limits_commit_update(nbd->disk->queue, &lim);
> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
> index 631dca2e4e8442..73e4aecf5bb492 100644
> --- a/drivers/block/null_blk/main.c
> +++ b/drivers/block/null_blk/main.c
> @@ -1928,6 +1928,13 @@ static int null_add_dev(struct nullb_device *dev)
> goto out_cleanup_tags;
> }
>
> + if (dev->cache_size > 0) {
> + set_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);
> + lim.features |= BLK_FEAT_WRITE_CACHE;
> + if (dev->fua)
> + lim.features |= BLK_FEAT_FUA;
> + }
> +
> nullb->disk = blk_mq_alloc_disk(nullb->tag_set, &lim, nullb);
> if (IS_ERR(nullb->disk)) {
> rv = PTR_ERR(nullb->disk);
> @@ -1940,11 +1947,6 @@ static int null_add_dev(struct nullb_device *dev)
> nullb_setup_bwtimer(nullb);
> }
>
> - if (dev->cache_size > 0) {
> - set_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);
> - blk_queue_write_cache(nullb->q, true, dev->fua);
> - }
> -
> nullb->q->queuedata = nullb;
> blk_queue_flag_set(QUEUE_FLAG_NONROT, nullb->q);
>
> diff --git a/drivers/block/ps3disk.c b/drivers/block/ps3disk.c
> index b810ac0a5c4b97..8b73cf459b5937 100644
> --- a/drivers/block/ps3disk.c
> +++ b/drivers/block/ps3disk.c
> @@ -388,9 +388,8 @@ static int ps3disk_probe(struct ps3_system_bus_device *_dev)
> .max_segments = -1,
> .max_segment_size = dev->bounce_size,
> .dma_alignment = dev->blk_size - 1,
> + .features = BLK_FEAT_WRITE_CACHE,
> };
> -
> - struct request_queue *queue;
> struct gendisk *gendisk;
>
> if (dev->blk_size < 512) {
> @@ -447,10 +446,6 @@ static int ps3disk_probe(struct ps3_system_bus_device *_dev)
> goto fail_free_tag_set;
> }
>
> - queue = gendisk->queue;
> -
> - blk_queue_write_cache(queue, true, false);
> -
> priv->gendisk = gendisk;
> gendisk->major = ps3disk_major;
> gendisk->first_minor = devidx * PS3DISK_MINORS;
> diff --git a/drivers/block/rnbd/rnbd-clt.c b/drivers/block/rnbd/rnbd-clt.c
> index b7ffe03c61606d..02c4b173182719 100644
> --- a/drivers/block/rnbd/rnbd-clt.c
> +++ b/drivers/block/rnbd/rnbd-clt.c
> @@ -1389,6 +1389,12 @@ static int rnbd_client_setup_device(struct rnbd_clt_dev *dev,
> le32_to_cpu(rsp->max_discard_sectors);
> }
>
> + if (rsp->cache_policy & RNBD_WRITEBACK) {
> + lim.features |= BLK_FEAT_WRITE_CACHE;
> + if (rsp->cache_policy & RNBD_FUA)
> + lim.features |= BLK_FEAT_FUA;
> + }
> +
> dev->gd = blk_mq_alloc_disk(&dev->sess->tag_set, &lim, dev);
> if (IS_ERR(dev->gd))
> return PTR_ERR(dev->gd);
> @@ -1397,10 +1403,6 @@ static int rnbd_client_setup_device(struct rnbd_clt_dev *dev,
>
> blk_queue_flag_set(QUEUE_FLAG_SAME_COMP, dev->queue);
> blk_queue_flag_set(QUEUE_FLAG_SAME_FORCE, dev->queue);
> - blk_queue_write_cache(dev->queue,
> - !!(rsp->cache_policy & RNBD_WRITEBACK),
> - !!(rsp->cache_policy & RNBD_FUA));
> -
> return rnbd_clt_setup_gen_disk(dev, rsp, idx);
> }
>
> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> index 4e159948c912c2..e45c65c1848d31 100644
> --- a/drivers/block/ublk_drv.c
> +++ b/drivers/block/ublk_drv.c
> @@ -487,8 +487,6 @@ static void ublk_dev_param_basic_apply(struct ublk_device *ub)
> struct request_queue *q = ub->ub_disk->queue;
> const struct ublk_param_basic *p = &ub->params.basic;
>
> - blk_queue_write_cache(q, p->attrs & UBLK_ATTR_VOLATILE_CACHE,
> - p->attrs & UBLK_ATTR_FUA);
> if (p->attrs & UBLK_ATTR_ROTATIONAL)
> blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
> else
> @@ -2210,6 +2208,12 @@ static int ublk_ctrl_start_dev(struct ublk_device *ub, struct io_uring_cmd *cmd)
> lim.max_zone_append_sectors = p->max_zone_append_sectors;
> }
>
> + if (ub->params.basic.attrs & UBLK_ATTR_VOLATILE_CACHE) {
> + lim.features |= BLK_FEAT_WRITE_CACHE;
> + if (ub->params.basic.attrs & UBLK_ATTR_FUA)
> + lim.features |= BLK_FEAT_FUA;
> + }
> +
> if (wait_for_completion_interruptible(&ub->completion) != 0)
> return -EINTR;
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 378b241911ca87..b1a3c293528519 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -1100,6 +1100,7 @@ cache_type_store(struct device *dev, struct device_attribute *attr,
> struct gendisk *disk = dev_to_disk(dev);
> struct virtio_blk *vblk = disk->private_data;
> struct virtio_device *vdev = vblk->vdev;
> + struct queue_limits lim;
> int i;
>
> BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
> @@ -1108,7 +1109,17 @@ cache_type_store(struct device *dev, struct device_attribute *attr,
> return i;
>
> virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i);
> - blk_queue_write_cache(disk->queue, virtblk_get_cache_mode(vdev), false);
> +
> + lim = queue_limits_start_update(disk->queue);
> + if (virtblk_get_cache_mode(vdev))
> + lim.features |= BLK_FEAT_WRITE_CACHE;
> + else
> + lim.features &= ~BLK_FEAT_WRITE_CACHE;
> + blk_mq_freeze_queue(disk->queue);
> + i = queue_limits_commit_update(disk->queue, &lim);
> + blk_mq_unfreeze_queue(disk->queue);
> + if (i)
> + return i;
> return count;
> }
>
> @@ -1504,6 +1515,9 @@ static int virtblk_probe(struct virtio_device *vdev)
> if (err)
> goto out_free_tags;
>
> + if (virtblk_get_cache_mode(vdev))
> + lim.features |= BLK_FEAT_WRITE_CACHE;
> +
> vblk->disk = blk_mq_alloc_disk(&vblk->tag_set, &lim, vblk);
> if (IS_ERR(vblk->disk)) {
> err = PTR_ERR(vblk->disk);
> @@ -1519,10 +1533,6 @@ static int virtblk_probe(struct virtio_device *vdev)
> vblk->disk->fops = &virtblk_fops;
> vblk->index = index;
>
> - /* configure queue flush support */
> - blk_queue_write_cache(vblk->disk->queue, virtblk_get_cache_mode(vdev),
> - false);
> -
> /* If disk is read-only in the host, the guest should obey */
> if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
> set_disk_ro(vblk->disk, 1);
> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> index 9794ac2d3299d1..de38e025769b14 100644
> --- a/drivers/block/xen-blkfront.c
> +++ b/drivers/block/xen-blkfront.c
> @@ -956,6 +956,12 @@ static void blkif_set_queue_limits(const struct blkfront_info *info,
> lim->max_secure_erase_sectors = UINT_MAX;
> }
>
> + if (info->feature_flush) {
> + lim->features |= BLK_FEAT_WRITE_CACHE;
> + if (info->feature_fua)
> + lim->features |= BLK_FEAT_FUA;
> + }
> +
> /* Hard sector size and max sectors impersonate the equiv. hardware. */
> lim->logical_block_size = info->sector_size;
> lim->physical_block_size = info->physical_sector_size;
> @@ -1150,9 +1156,6 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
> info->sector_size = sector_size;
> info->physical_sector_size = physical_sector_size;
>
> - blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
> - info->feature_fua ? true : false);
> -
> pr_info("blkfront: %s: %s %s %s %s %s %s %s\n",
> info->gd->disk_name, flush_info(info),
> "persistent grants:", info->feature_persistent ?
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index 4d11fc664cb0b8..cb6595c8b5514e 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -897,7 +897,6 @@ static int bcache_device_init(struct bcache_device *d, unsigned int block_size,
> sector_t sectors, struct block_device *cached_bdev,
> const struct block_device_operations *ops)
> {
> - struct request_queue *q;
> const size_t max_stripes = min_t(size_t, INT_MAX,
> SIZE_MAX / sizeof(atomic_t));
> struct queue_limits lim = {
> @@ -909,6 +908,7 @@ static int bcache_device_init(struct bcache_device *d, unsigned int block_size,
> .io_min = block_size,
> .logical_block_size = block_size,
> .physical_block_size = block_size,
> + .features = BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA,
> };
> uint64_t n;
> int idx;
> @@ -975,12 +975,7 @@ static int bcache_device_init(struct bcache_device *d, unsigned int block_size,
> d->disk->fops = ops;
> d->disk->private_data = d;
>
> - q = d->disk->queue;
> -
> blk_queue_flag_set(QUEUE_FLAG_NONROT, d->disk->queue);
> -
> - blk_queue_write_cache(q, true, true);
> -
> return 0;
>
> out_bioset_exit:
> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index fd789eeb62d943..fbe125d55e25b4 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -1686,34 +1686,16 @@ int dm_calculate_queue_limits(struct dm_table *t,
> return validate_hardware_logical_block_alignment(t, limits);
> }
>
> -static int device_flush_capable(struct dm_target *ti, struct dm_dev *dev,
> - sector_t start, sector_t len, void *data)
> -{
> - unsigned long flush = (unsigned long) data;
> - struct request_queue *q = bdev_get_queue(dev->bdev);
> -
> - return (q->queue_flags & flush);
> -}
> -
> -static bool dm_table_supports_flush(struct dm_table *t, unsigned long flush)
> +/*
> + * Check if an target requires flush support even if none of the underlying
> + * devices need it (e.g. to persist target-specific metadata).
> + */
> +static bool dm_table_supports_flush(struct dm_table *t)
> {
> - /*
> - * Require at least one underlying device to support flushes.
> - * t->devices includes internal dm devices such as mirror logs
> - * so we need to use iterate_devices here, which targets
> - * supporting flushes must provide.
> - */
> for (unsigned int i = 0; i < t->num_targets; i++) {
> struct dm_target *ti = dm_table_get_target(t, i);
>
> - if (!ti->num_flush_bios)
> - continue;
> -
> - if (ti->flush_supported)
> - return true;
> -
> - if (ti->type->iterate_devices &&
> - ti->type->iterate_devices(ti, device_flush_capable, (void *) flush))
> + if (ti->num_flush_bios && ti->flush_supported)
> return true;
> }
>
> @@ -1855,7 +1837,6 @@ static int device_requires_stable_pages(struct dm_target *ti,
> int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
> struct queue_limits *limits)
> {
> - bool wc = false, fua = false;
> int r;
>
> if (dm_table_supports_nowait(t))
> @@ -1876,12 +1857,8 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
> if (!dm_table_supports_secure_erase(t))
> limits->max_secure_erase_sectors = 0;
>
> - if (dm_table_supports_flush(t, (1UL << QUEUE_FLAG_WC))) {
> - wc = true;
> - if (dm_table_supports_flush(t, (1UL << QUEUE_FLAG_FUA)))
> - fua = true;
> - }
> - blk_queue_write_cache(q, wc, fua);
> + if (dm_table_supports_flush(t))
> + limits->features |= BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA;
>
> if (dm_table_supports_dax(t, device_not_dax_capable)) {
> blk_queue_flag_set(QUEUE_FLAG_DAX, q);
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 67ece2cd725f50..2f4c5d1755d857 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -5785,7 +5785,10 @@ struct mddev *md_alloc(dev_t dev, char *name)
> int partitioned;
> int shift;
> int unit;
> - int error ;
> + int error;
> + struct queue_limits lim = {
> + .features = BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA,
> + };
>
> /*
> * Wait for any previous instance of this device to be completely
> @@ -5825,7 +5828,7 @@ struct mddev *md_alloc(dev_t dev, char *name)
> */
> mddev->hold_active = UNTIL_STOP;
>
> - disk = blk_alloc_disk(NULL, NUMA_NO_NODE);
> + disk = blk_alloc_disk(&lim, NUMA_NO_NODE);
> if (IS_ERR(disk)) {
> error = PTR_ERR(disk);
> goto out_free_mddev;
> @@ -5843,7 +5846,6 @@ struct mddev *md_alloc(dev_t dev, char *name)
> disk->fops = &md_fops;
> disk->private_data = mddev;
>
> - blk_queue_write_cache(disk->queue, true, true);
> disk->events |= DISK_EVENT_MEDIA_CHANGE;
> mddev->gendisk = disk;
> error = add_disk(disk);
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index 367509b5b6466c..2c9963248fcbd6 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -2466,8 +2466,7 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
> struct mmc_blk_data *md;
> int devidx, ret;
> char cap_str[10];
> - bool cache_enabled = false;
> - bool fua_enabled = false;
> + unsigned int features = 0;
>
> devidx = ida_alloc_max(&mmc_blk_ida, max_devices - 1, GFP_KERNEL);
> if (devidx < 0) {
> @@ -2499,7 +2498,24 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
> */
> md->read_only = mmc_blk_readonly(card);
>
> - md->disk = mmc_init_queue(&md->queue, card);
> + if (mmc_host_cmd23(card->host)) {
> + if ((mmc_card_mmc(card) &&
> + card->csd.mmca_vsn >= CSD_SPEC_VER_3) ||
> + (mmc_card_sd(card) &&
> + card->scr.cmds & SD_SCR_CMD23_SUPPORT))
> + md->flags |= MMC_BLK_CMD23;
> + }
> +
> + if (md->flags & MMC_BLK_CMD23 &&
> + ((card->ext_csd.rel_param & EXT_CSD_WR_REL_PARAM_EN) ||
> + card->ext_csd.rel_sectors)) {
> + md->flags |= MMC_BLK_REL_WR;
> + features |= (BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA);
> + } else if (mmc_cache_enabled(card->host)) {
> + features |= BLK_FEAT_WRITE_CACHE;
> + }
> +
> + md->disk = mmc_init_queue(&md->queue, card, features);
> if (IS_ERR(md->disk)) {
> ret = PTR_ERR(md->disk);
> goto err_kfree;
> @@ -2539,26 +2555,6 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
>
> set_capacity(md->disk, size);
>
> - if (mmc_host_cmd23(card->host)) {
> - if ((mmc_card_mmc(card) &&
> - card->csd.mmca_vsn >= CSD_SPEC_VER_3) ||
> - (mmc_card_sd(card) &&
> - card->scr.cmds & SD_SCR_CMD23_SUPPORT))
> - md->flags |= MMC_BLK_CMD23;
> - }
> -
> - if (md->flags & MMC_BLK_CMD23 &&
> - ((card->ext_csd.rel_param & EXT_CSD_WR_REL_PARAM_EN) ||
> - card->ext_csd.rel_sectors)) {
> - md->flags |= MMC_BLK_REL_WR;
> - fua_enabled = true;
> - cache_enabled = true;
> - }
> - if (mmc_cache_enabled(card->host))
> - cache_enabled = true;
> -
> - blk_queue_write_cache(md->queue.queue, cache_enabled, fua_enabled);
> -
> string_get_size((u64)size, 512, STRING_UNITS_2,
> cap_str, sizeof(cap_str));
> pr_info("%s: %s %s %s%s\n",
> diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
> index 241cdc2b2a2a3b..97ff993d31570c 100644
> --- a/drivers/mmc/core/queue.c
> +++ b/drivers/mmc/core/queue.c
> @@ -344,10 +344,12 @@ static const struct blk_mq_ops mmc_mq_ops = {
> };
>
> static struct gendisk *mmc_alloc_disk(struct mmc_queue *mq,
> - struct mmc_card *card)
> + struct mmc_card *card, unsigned int features)
> {
> struct mmc_host *host = card->host;
> - struct queue_limits lim = { };
> + struct queue_limits lim = {
> + .features = features,
> + };
> struct gendisk *disk;
>
> if (mmc_can_erase(card))
> @@ -413,10 +415,12 @@ static inline bool mmc_merge_capable(struct mmc_host *host)
> * mmc_init_queue - initialise a queue structure.
> * @mq: mmc queue
> * @card: mmc card to attach this queue
> + * @features: block layer features (BLK_FEAT_*)
> *
> * Initialise a MMC card request queue.
> */
> -struct gendisk *mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card)
> +struct gendisk *mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
> + unsigned int features)
> {
> struct mmc_host *host = card->host;
> struct gendisk *disk;
> @@ -460,7 +464,7 @@ struct gendisk *mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card)
> return ERR_PTR(ret);
>
>
> - disk = mmc_alloc_disk(mq, card);
> + disk = mmc_alloc_disk(mq, card, features);
> if (IS_ERR(disk))
> blk_mq_free_tag_set(&mq->tag_set);
> return disk;
> diff --git a/drivers/mmc/core/queue.h b/drivers/mmc/core/queue.h
> index 9ade3bcbb714e4..1498840a4ea008 100644
> --- a/drivers/mmc/core/queue.h
> +++ b/drivers/mmc/core/queue.h
> @@ -94,7 +94,8 @@ struct mmc_queue {
> struct work_struct complete_work;
> };
>
> -struct gendisk *mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card);
> +struct gendisk *mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
> + unsigned int features);
> extern void mmc_cleanup_queue(struct mmc_queue *);
> extern void mmc_queue_suspend(struct mmc_queue *);
> extern void mmc_queue_resume(struct mmc_queue *);
> diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
> index 3caa0717d46c01..1b9f57f231e8be 100644
> --- a/drivers/mtd/mtd_blkdevs.c
> +++ b/drivers/mtd/mtd_blkdevs.c
> @@ -336,6 +336,8 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
> lim.logical_block_size = tr->blksize;
> if (tr->discard)
> lim.max_hw_discard_sectors = UINT_MAX;
> + if (tr->flush)
> + lim.features |= BLK_FEAT_WRITE_CACHE;
>
> /* Create gendisk */
> gd = blk_mq_alloc_disk(new->tag_set, &lim, new);
> @@ -373,9 +375,6 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
> spin_lock_init(&new->queue_lock);
> INIT_LIST_HEAD(&new->rq_list);
>
> - if (tr->flush)
> - blk_queue_write_cache(new->rq, true, false);
> -
> blk_queue_flag_set(QUEUE_FLAG_NONROT, new->rq);
> blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, new->rq);
>
> diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
> index 598fe2e89bda45..aff818469c114c 100644
> --- a/drivers/nvdimm/pmem.c
> +++ b/drivers/nvdimm/pmem.c
> @@ -455,6 +455,7 @@ static int pmem_attach_disk(struct device *dev,
> .logical_block_size = pmem_sector_size(ndns),
> .physical_block_size = PAGE_SIZE,
> .max_hw_sectors = UINT_MAX,
> + .features = BLK_FEAT_WRITE_CACHE,
> };
> int nid = dev_to_node(dev), fua;
> struct resource *res = &nsio->res;
> @@ -495,6 +496,8 @@ static int pmem_attach_disk(struct device *dev,
> dev_warn(dev, "unable to guarantee persistence of writes\n");
> fua = 0;
> }
> + if (fua)
> + lim.features |= BLK_FEAT_FUA;
>
> if (!devm_request_mem_region(dev, res->start, resource_size(res),
> dev_name(&ndns->dev))) {
> @@ -543,7 +546,6 @@ static int pmem_attach_disk(struct device *dev,
> }
> pmem->virt_addr = addr;
>
> - blk_queue_write_cache(q, true, fua);
> blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
> blk_queue_flag_set(QUEUE_FLAG_SYNCHRONOUS, q);
> if (pmem->pfn_flags & PFN_MAP)
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 5a673fa5cb2612..9fc5e36fe2e55e 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -2056,7 +2056,6 @@ static int nvme_update_ns_info_generic(struct nvme_ns *ns,
> static int nvme_update_ns_info_block(struct nvme_ns *ns,
> struct nvme_ns_info *info)
> {
> - bool vwc = ns->ctrl->vwc & NVME_CTRL_VWC_PRESENT;
> struct queue_limits lim;
> struct nvme_id_ns_nvm *nvm = NULL;
> struct nvme_zone_info zi = {};
> @@ -2106,6 +2105,11 @@ static int nvme_update_ns_info_block(struct nvme_ns *ns,
> ns->head->ids.csi == NVME_CSI_ZNS)
> nvme_update_zone_info(ns, &lim, &zi);
>
> + if (ns->ctrl->vwc & NVME_CTRL_VWC_PRESENT)
> + lim.features |= BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA;
> + else
> + lim.features &= ~(BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA);
> +
> /*
> * Register a metadata profile for PI, or the plain non-integrity NVMe
> * metadata masquerading as Type 0 if supported, otherwise reject block
> @@ -2132,7 +2136,6 @@ static int nvme_update_ns_info_block(struct nvme_ns *ns,
> if ((id->dlfeat & 0x7) == 0x1 && (id->dlfeat & (1 << 3)))
> ns->head->features |= NVME_NS_DEAC;
> set_disk_ro(ns->disk, nvme_ns_is_readonly(ns, info));
> - blk_queue_write_cache(ns->disk->queue, vwc, vwc);
> set_bit(NVME_NS_READY, &ns->flags);
> blk_mq_unfreeze_queue(ns->disk->queue);
>
> diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
> index 12c59db02539e5..3d0e23a0a4ddd8 100644
> --- a/drivers/nvme/host/multipath.c
> +++ b/drivers/nvme/host/multipath.c
> @@ -521,7 +521,6 @@ static void nvme_requeue_work(struct work_struct *work)
> int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head)
> {
> struct queue_limits lim;
> - bool vwc = false;
>
> mutex_init(&head->lock);
> bio_list_init(&head->requeue_list);
> @@ -562,11 +561,6 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head)
> if (ctrl->tagset->nr_maps > HCTX_TYPE_POLL &&
> ctrl->tagset->map[HCTX_TYPE_POLL].nr_queues)
> blk_queue_flag_set(QUEUE_FLAG_POLL, head->disk->queue);
> -
> - /* we need to propagate up the VMC settings */
> - if (ctrl->vwc & NVME_CTRL_VWC_PRESENT)
> - vwc = true;
> - blk_queue_write_cache(head->disk->queue, vwc, vwc);
> return 0;
> }
>
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index 5bfed61c70db8f..8764ea14c9b881 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -120,17 +120,18 @@ static const char *sd_cache_types[] = {
> "write back, no read (daft)"
> };
>
> -static void sd_set_flush_flag(struct scsi_disk *sdkp)
> +static void sd_set_flush_flag(struct scsi_disk *sdkp,
> + struct queue_limits *lim)
> {
> - bool wc = false, fua = false;
> -
> if (sdkp->WCE) {
> - wc = true;
> + lim->features |= BLK_FEAT_WRITE_CACHE;
> if (sdkp->DPOFUA)
> - fua = true;
> + lim->features |= BLK_FEAT_FUA;
> + else
> + lim->features &= ~BLK_FEAT_FUA;
> + } else {
> + lim->features &= ~(BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA);
> }
> -
> - blk_queue_write_cache(sdkp->disk->queue, wc, fua);
> }
>
> static ssize_t
> @@ -168,9 +169,18 @@ cache_type_store(struct device *dev, struct device_attribute *attr,
> wce = (ct & 0x02) && !sdkp->write_prot ? 1 : 0;
>
> if (sdkp->cache_override) {
> + struct queue_limits lim;
> +
> sdkp->WCE = wce;
> sdkp->RCD = rcd;
> - sd_set_flush_flag(sdkp);
> +
> + lim = queue_limits_start_update(sdkp->disk->queue);
> + sd_set_flush_flag(sdkp, &lim);
> + blk_mq_freeze_queue(sdkp->disk->queue);
> + ret = queue_limits_commit_update(sdkp->disk->queue, &lim);
> + blk_mq_unfreeze_queue(sdkp->disk->queue);
> + if (ret)
> + return ret;
> return count;
> }
>
> @@ -3659,7 +3669,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
> * We now have all cache related info, determine how we deal
> * with flush requests.
> */
> - sd_set_flush_flag(sdkp);
> + sd_set_flush_flag(sdkp, &lim);
>
> /* Initial block count limit based on CDB TRANSFER LENGTH field size. */
> dev_max = sdp->use_16_for_rw ? SD_MAX_XFER_BLOCKS : SD_DEF_XFER_BLOCKS;
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index c792d4d81e5fcc..4e8931a2c76b07 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -282,6 +282,28 @@ static inline bool blk_op_is_passthrough(blk_opf_t op)
> return op == REQ_OP_DRV_IN || op == REQ_OP_DRV_OUT;
> }
>
> +/* flags set by the driver in queue_limits.features */
> +enum {
> + /* supports a a volatile write cache */
> + BLK_FEAT_WRITE_CACHE = (1u << 0),
> +
> + /* supports passing on the FUA bit */
> + BLK_FEAT_FUA = (1u << 1),
> +};
> +
> +/*
> + * Flags automatically inherited when stacking limits.
> + */
> +#define BLK_FEAT_INHERIT_MASK \
> + (BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA)
> +
> +
> +/* internal flags in queue_limits.flags */
> +enum {
> + /* do not send FLUSH or FUA command despite advertised write cache */
> + BLK_FLAGS_WRITE_CACHE_DISABLED = (1u << 31),
> +};
> +
> /*
> * BLK_BOUNCE_NONE: never bounce (default)
> * BLK_BOUNCE_HIGH: bounce all highmem pages
> @@ -292,6 +314,8 @@ enum blk_bounce {
> };
>
> struct queue_limits {
> + unsigned int features;
> + unsigned int flags;
> enum blk_bounce bounce;
> unsigned long seg_boundary_mask;
> unsigned long virt_boundary_mask;
> @@ -536,12 +560,9 @@ struct request_queue {
> #define QUEUE_FLAG_ADD_RANDOM 10 /* Contributes to random pool */
> #define QUEUE_FLAG_SYNCHRONOUS 11 /* always completes in submit context */
> #define QUEUE_FLAG_SAME_FORCE 12 /* force complete on same CPU */
> -#define QUEUE_FLAG_HW_WC 13 /* Write back caching supported */
> #define QUEUE_FLAG_INIT_DONE 14 /* queue is initialized */
> #define QUEUE_FLAG_STABLE_WRITES 15 /* don't modify blks until WB is done */
> #define QUEUE_FLAG_POLL 16 /* IO polling enabled if set */
> -#define QUEUE_FLAG_WC 17 /* Write back caching */
> -#define QUEUE_FLAG_FUA 18 /* device supports FUA writes */
> #define QUEUE_FLAG_DAX 19 /* device supports DAX */
> #define QUEUE_FLAG_STATS 20 /* track IO start and completion times */
> #define QUEUE_FLAG_REGISTERED 22 /* queue has been registered to a disk */
> @@ -951,7 +972,6 @@ void queue_limits_stack_bdev(struct queue_limits *t, struct block_device *bdev,
> sector_t offset, const char *pfx);
> extern void blk_queue_update_dma_pad(struct request_queue *, unsigned int);
> extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);
> -extern void blk_queue_write_cache(struct request_queue *q, bool enabled, bool fua);
>
> struct blk_independent_access_ranges *
> disk_alloc_independent_access_ranges(struct gendisk *disk, int nr_ia_ranges);
> @@ -1305,14 +1325,20 @@ static inline bool bdev_stable_writes(struct block_device *bdev)
> return test_bit(QUEUE_FLAG_STABLE_WRITES, &q->queue_flags);
> }
>
> +static inline bool blk_queue_write_cache(struct request_queue *q)
> +{
> + return (q->limits.features & BLK_FEAT_WRITE_CACHE) &&
> + (q->limits.flags & BLK_FLAGS_WRITE_CACHE_DISABLED);
> +}
> +
> static inline bool bdev_write_cache(struct block_device *bdev)
> {
> - return test_bit(QUEUE_FLAG_WC, &bdev_get_queue(bdev)->queue_flags);
> + return blk_queue_write_cache(bdev_get_queue(bdev));
> }
>
> static inline bool bdev_fua(struct block_device *bdev)
> {
> - return test_bit(QUEUE_FLAG_FUA, &bdev_get_queue(bdev)->queue_flags);
> + return bdev_get_queue(bdev)->limits.features & BLK_FEAT_FUA;
> }
>
> static inline bool bdev_nowait(struct block_device *bdev)
> --
> 2.43.0
>
>
