bdi: replace BDI_CAP_STABLE_WRITES with a queue and a sb flag

The BDI_CAP_STABLE_WRITES is one of the few bits of information in the
backing_dev_info shared between the block drivers and the writeback code.
To help untangling the dependency replace it with a queue flag and a
superblock flag derived from it.  This also helps with the case of e.g.
a file system requiring stable writes due to its own checksumming, but
not forcing it on other users of the block device like the swap code.

One downside is that we an't support the stable_pages_required bdi
attribute in sysfs anymore.  It is replaced with a queue attribute which
also is writable for easier testing.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-integrity.c b/block/blk-integrity.c
index c03705cbb9c9f20b9f5f9f2b123fc5883e4287ec..2b36a8f9b81390e9efdfe30711c8369de8d44992 100644 (file)
--- a/block/blk-integrity.c
+++ b/block/blk-integrity.c
@@ -408,7 +408,7 @@ void blk_integrity_register(struct gendisk *disk, struct blk_integrity *template
        bi->tuple_size = template->tuple_size;
        bi->tag_size = template->tag_size;
 
-       disk->queue->backing_dev_info->capabilities |= BDI_CAP_STABLE_WRITES;
+       blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, disk->queue);
 
 #ifdef CONFIG_BLK_INLINE_ENCRYPTION
        if (disk->queue->ksm) {
@@ -428,7 +428,7 @@ EXPORT_SYMBOL(blk_integrity_register);
  */
 void blk_integrity_unregister(struct gendisk *disk)
 {
-       disk->queue->backing_dev_info->capabilities &= ~BDI_CAP_STABLE_WRITES;
+       blk_queue_flag_clear(QUEUE_FLAG_STABLE_WRITES, disk->queue);
        memset(&disk->queue->integrity, 0, sizeof(struct blk_integrity));
 }
 EXPORT_SYMBOL(blk_integrity_unregister);

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 645b7f800cb827795444ae6405263d8a9f1c3bf8..3094542e12ae0fa468f242a897b1d08b35fbe83f 100644 (file)
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -116,6 +116,7 @@ static const char *const blk_queue_flag_name[] = {
        QUEUE_FLAG_NAME(SAME_FORCE),
        QUEUE_FLAG_NAME(DEAD),
        QUEUE_FLAG_NAME(INIT_DONE),
+       QUEUE_FLAG_NAME(STABLE_WRITES),
        QUEUE_FLAG_NAME(POLL),
        QUEUE_FLAG_NAME(WC),
        QUEUE_FLAG_NAME(FUA),

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 869ed21a9edcab078dacde2c65d6b11066492ab6..76b54c7750b07ee1b0b634e459be9d1c24101ef1 100644 (file)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -287,6 +287,7 @@ queue_##name##_store(struct request_queue *q, const char *page, size_t count) \
 QUEUE_SYSFS_BIT_FNS(nonrot, NONROT, 1);
 QUEUE_SYSFS_BIT_FNS(random, ADD_RANDOM, 0);
 QUEUE_SYSFS_BIT_FNS(iostats, IO_STAT, 0);
+QUEUE_SYSFS_BIT_FNS(stable_writes, STABLE_WRITES, 0);
 #undef QUEUE_SYSFS_BIT_FNS
 
 static ssize_t queue_zoned_show(struct request_queue *q, char *page)
@@ -613,6 +614,7 @@ static struct queue_sysfs_entry queue_hw_sector_size_entry = {
 QUEUE_RW_ENTRY(queue_nonrot, "rotational");
 QUEUE_RW_ENTRY(queue_iostats, "iostats");
 QUEUE_RW_ENTRY(queue_random, "add_random");
+QUEUE_RW_ENTRY(queue_stable_writes, "stable_writes");
 
 static struct attribute *queue_attrs[] = {
        &queue_requests_entry.attr,
@@ -645,6 +647,7 @@ static struct attribute *queue_attrs[] = {
        &queue_nomerges_entry.attr,
        &queue_rq_affinity_entry.attr,
        &queue_iostats_entry.attr,
+       &queue_stable_writes_entry.attr,
        &queue_random_entry.attr,
        &queue_poll_entry.attr,
        &queue_wc_entry.attr,

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 5d3923c0997ce0e479b17d63231c2ab9bc947265..cf5b016358cdab975ca601973c7a591f13aeb158 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -5022,7 +5022,7 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
        }
 
        if (!ceph_test_opt(rbd_dev->rbd_client->client, NOCRC))
-               q->backing_dev_info->capabilities |= BDI_CAP_STABLE_WRITES;
+               blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, q);
 
        /*
         * disk_release() expects a queue ref from add_disk() and will

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index e21ca844d7c291475e8aac05038112924201c51a..bff3d4021c18e17ac43f80edf76f17b84c30f6d9 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1955,7 +1955,7 @@ static int zram_add(void)
        if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
                blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX);
 
-       zram->disk->queue->backing_dev_info->capabilities |= BDI_CAP_STABLE_WRITES;
+       blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, zram->disk->queue);
        device_add_disk(NULL, zram->disk, zram_disk_attr_groups);
 
        strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index ef2757012f59d533db640308324b630dd6abaabe..405d7cf10eb97366fd9713f7e16890acbe4179f3 100644 (file)
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1815,7 +1815,7 @@ static int device_requires_stable_pages(struct dm_target *ti,
 {
        struct request_queue *q = bdev_get_queue(dev->bdev);
 
-       return q && bdi_cap_stable_pages_required(q->backing_dev_info);
+       return q && blk_queue_stable_writes(q);
 }
 
 /*
@@ -1900,9 +1900,9 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
         * because they do their own checksumming.
         */
        if (dm_table_requires_stable_pages(t))
-               q->backing_dev_info->capabilities |= BDI_CAP_STABLE_WRITES;
+               blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, q);
        else
-               q->backing_dev_info->capabilities &= ~BDI_CAP_STABLE_WRITES;
+               blk_queue_flag_clear(QUEUE_FLAG_STABLE_WRITES, q);
 
        /*
         * Determine whether or not this queue's I/O timings contribute

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 7ace1f76b14736feb13cb28078313ade5c807e03..d589d26c86ea3f3bfbb98ed205ab011beb6946d3 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -6638,14 +6638,14 @@ raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
        if (!conf)
                err = -ENODEV;
        else if (new != conf->skip_copy) {
+               struct request_queue *q = mddev->queue;
+
                mddev_suspend(mddev);
                conf->skip_copy = new;
                if (new)
-                       mddev->queue->backing_dev_info->capabilities |=
-                               BDI_CAP_STABLE_WRITES;
+                       blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, q);
                else
-                       mddev->queue->backing_dev_info->capabilities &=
-                               ~BDI_CAP_STABLE_WRITES;
+                       blk_queue_flag_clear(QUEUE_FLAG_STABLE_WRITES, q);
                mddev_resume(mddev);
        }
        mddev_unlock(mddev);

diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
index 6c022ef0f84d7278a5a1073c4cfd03f5b1bf4ad8..80fe3852ce0f7575187f70a87c4bc98d52979215 100644 (file)
--- a/drivers/mmc/core/queue.c
+++ b/drivers/mmc/core/queue.c
@@ -472,8 +472,7 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card)
        }
 
        if (mmc_host_is_spi(host) && host->use_spi_crc)
-               mq->queue->backing_dev_info->capabilities |=
-                       BDI_CAP_STABLE_WRITES;
+               blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, mq->queue);
 
        mq->queue->queuedata = mq;
        blk_queue_rq_timeout(mq->queue, 60 * HZ);

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 741c9bfa8e14c78aefcf0020d3110e5e8278f90f..c190c56bf7020d0cfc49def5975e1e6f18d169ec 100644 (file)
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3926,8 +3926,7 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid)
                goto out_free_ns;
 
        if (ctrl->opts && ctrl->opts->data_digest)
-               ns->queue->backing_dev_info->capabilities
-                       |= BDI_CAP_STABLE_WRITES;
+               blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, ns->queue);
 
        blk_queue_flag_set(QUEUE_FLAG_NONROT, ns->queue);
        if (ctrl->ops->flags & NVME_F_PCI_P2PDMA)

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index d4ba736c6c8905cda938db0d15ea4b540e50ccf0..74896be40c17699f5f2453620abaaae02b56fcb7 100644 (file)
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -673,13 +673,9 @@ void nvme_mpath_add_disk(struct nvme_ns *ns, struct nvme_id_ns *id)
                nvme_mpath_set_live(ns);
        }
 
-       if (bdi_cap_stable_pages_required(ns->queue->backing_dev_info)) {
-               struct gendisk *disk = ns->head->disk;
-
-               if (disk)
-                       disk->queue->backing_dev_info->capabilities |=
-                                       BDI_CAP_STABLE_WRITES;
-       }
+       if (blk_queue_stable_writes(ns->queue) && ns->head->disk)
+               blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES,
+                                  ns->head->disk->queue);
 }
 
 void nvme_mpath_remove_disk(struct nvme_ns_head *head)

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index b5dd1caae5e92d03f050bdc427985f24c41917a0..a622f334c933f572a6c8b7ba118b5d3cb8d4f852 100644 (file)
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -962,8 +962,8 @@ static int iscsi_sw_tcp_slave_configure(struct scsi_device *sdev)
        struct iscsi_conn *conn = session->leadconn;
 
        if (conn->datadgst_en)
-               sdev->request_queue->backing_dev_info->capabilities
-                       |= BDI_CAP_STABLE_WRITES;
+               blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES,
+                                  sdev->request_queue);
        blk_queue_dma_alignment(sdev->request_queue, 0);
        return 0;
 }

diff --git a/fs/super.c b/fs/super.c
index 904459b351199597d512db5228fe6db322c991e6..a51c2083cd6b181ad64f9fd8d7ef09b2bc7184bc 100644 (file)
--- a/fs/super.c
+++ b/fs/super.c
@@ -1256,6 +1256,8 @@ static int set_bdev_super(struct super_block *s, void *data)
        s->s_dev = s->s_bdev->bd_dev;
        s->s_bdi = bdi_get(s->s_bdev->bd_bdi);
 
+       if (blk_queue_stable_writes(s->s_bdev->bd_disk->queue))
+               s->s_iflags |= SB_I_STABLE_WRITES;
        return 0;
 }
 

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 860ea33571bce5486be5409df5f9017a1328a8bb..5da4ea3dd0cc5ce65259e5ec575ebfb08eaadabd 100644 (file)
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -126,7 +126,6 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
 #define BDI_CAP_NO_ACCT_DIRTY  0x00000001
 #define BDI_CAP_NO_WRITEBACK   0x00000002
 #define BDI_CAP_NO_ACCT_WB     0x00000004
-#define BDI_CAP_STABLE_WRITES  0x00000008
 #define BDI_CAP_STRICTLIMIT    0x00000010
 #define BDI_CAP_CGROUP_WRITEBACK 0x00000020
 
@@ -170,11 +169,6 @@ static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
 long congestion_wait(int sync, long timeout);
 long wait_iff_congested(int sync, long timeout);
 
-static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
-{
-       return bdi->capabilities & BDI_CAP_STABLE_WRITES;
-}
-
 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
 {
        return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 282f5ca424f14ab1a02cf878fc32dc7eeff12cc6..8e77f12de522140cb07f7643daac084449b29e00 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -606,6 +606,7 @@ struct request_queue {
 #define QUEUE_FLAG_SAME_FORCE  12      /* force complete on same CPU */
 #define QUEUE_FLAG_DEAD                13      /* queue tear-down finished */
 #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 */
@@ -635,6 +636,8 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q);
 #define blk_queue_noxmerges(q) \
        test_bit(QUEUE_FLAG_NOXMERGES, &(q)->queue_flags)
 #define blk_queue_nonrot(q)    test_bit(QUEUE_FLAG_NONROT, &(q)->queue_flags)
+#define blk_queue_stable_writes(q) \
+       test_bit(QUEUE_FLAG_STABLE_WRITES, &(q)->queue_flags)
 #define blk_queue_io_stat(q)   test_bit(QUEUE_FLAG_IO_STAT, &(q)->queue_flags)
 #define blk_queue_add_random(q)        test_bit(QUEUE_FLAG_ADD_RANDOM, &(q)->queue_flags)
 #define blk_queue_discard(q)   test_bit(QUEUE_FLAG_DISCARD, &(q)->queue_flags)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index fbd74df5ce5f346986d25168e898540a6fe47342..222465b7cf417873d2d464220c888ec993bcf5bc 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1385,6 +1385,7 @@ extern int send_sigurg(struct fown_struct *fown);
 #define SB_I_CGROUPWB  0x00000001      /* cgroup-aware writeback enabled */
 #define SB_I_NOEXEC    0x00000002      /* Ignore executables on this fs */
 #define SB_I_NODEV     0x00000004      /* Ignore devices on this fs */
+#define SB_I_STABLE_WRITES 0x00000008  /* don't modify blks until WB is done */
 
 /* sb->s_iflags to limit user namespace mounts */
 #define SB_I_USERNS_VISIBLE            0x00000010 /* fstype already mounted */

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 2dac3be61271278c60ec9cdbb128d40a9831ce86..8e3802bf03a968ad874d8150929853d0adfdf556 100644 (file)
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -204,10 +204,9 @@ static ssize_t stable_pages_required_show(struct device *dev,
                                          struct device_attribute *attr,
                                          char *page)
 {
-       struct backing_dev_info *bdi = dev_get_drvdata(dev);
-
-       return snprintf(page, PAGE_SIZE-1, "%d\n",
-                       bdi_cap_stable_pages_required(bdi) ? 1 : 0);
+       dev_warn_once(dev,
+               "the stable_pages_required attribute has been removed. Use the stable_writes queue attribute instead.\n");
+       return snprintf(page, PAGE_SIZE-1, "%d\n", 0);
 }
 static DEVICE_ATTR_RO(stable_pages_required);
 

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 4e4ddd67b71e589ede9a4679f61da802190de8a2..e9c36521461aaa3cfbd210886d9f3a9bced43e8a 100644 (file)
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2849,7 +2849,7 @@ EXPORT_SYMBOL_GPL(wait_on_page_writeback);
  */
 void wait_for_stable_page(struct page *page)
 {
-       if (bdi_cap_stable_pages_required(inode_to_bdi(page->mapping->host)))
+       if (page->mapping->host->i_sb->s_iflags & SB_I_STABLE_WRITES)
                wait_on_page_writeback(page);
 }
 EXPORT_SYMBOL_GPL(wait_for_stable_page);

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 96a7c47dd533e48bccfa8e56203cc22b7d9e4fda..65ef407512b5b096ccce7a4106305cbd37035c03 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3237,7 +3237,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
                goto bad_swap_unlock_inode;
        }
 
-       if (bdi_cap_stable_pages_required(inode_to_bdi(inode)))
+       if (p->bdev && blk_queue_stable_writes(p->bdev->bd_disk->queue))
                p->flags |= SWP_STABLE_WRITES;
 
        if (p->bdev && p->bdev->bd_disk->fops->rw_page)