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Fri, 12 Mar 2021 10:45:23 -0500 X-MC-Unique: -Ho6l87aMy6-rtkb91-Feg-1 Received: from mail.veeam.com (prgmbx01.amust.local [172.24.0.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx4.veeam.com (Postfix) with ESMTPS id F1A3B88818; Fri, 12 Mar 2021 18:45:21 +0300 (MSK) Received: from prgdevlinuxpatch01.amust.local (172.24.14.5) by prgmbx01.amust.local (172.24.0.171) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.721.2; Fri, 12 Mar 2021 16:45:19 +0100 From: Sergei Shtepa To: Christoph Hellwig , Mike Snitzer , Alasdair Kergon , Hannes Reinecke , Jens Axboe , , , , Date: Fri, 12 Mar 2021 18:44:55 +0300 Message-ID: <1615563895-28565-4-git-send-email-sergei.shtepa@veeam.com> In-Reply-To: <1615563895-28565-1-git-send-email-sergei.shtepa@veeam.com> References: <1615563895-28565-1-git-send-email-sergei.shtepa@veeam.com> MIME-Version: 1.0 X-Originating-IP: [172.24.14.5] X-ClientProxiedBy: prgmbx02.amust.local (172.24.0.172) To prgmbx01.amust.local (172.24.0.171) X-EsetResult: clean, is OK X-EsetId: 37303A29D2A50B58627366 X-Veeam-MMEX: True X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-loop: dm-devel@redhat.com Cc: pavel.tide@veeam.com, sergei.shtepa@veeam.com Subject: [dm-devel] [PATCH v7 3/3] dm: add DM_INTERPOSED_FLAG X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com DM_INTERPOSED_FLAG allow to create DM targets on "the fly". Underlying block device opens without a flag FMODE_EXCL. DM target receives bio from the original device via bdev_interposer. Signed-off-by: Sergei Shtepa --- drivers/md/dm-core.h | 3 ++ drivers/md/dm-ioctl.c | 13 ++++++++ drivers/md/dm-table.c | 61 +++++++++++++++++++++++++++++------ drivers/md/dm.c | 38 +++++++++++++++------- include/linux/device-mapper.h | 1 + include/uapi/linux/dm-ioctl.h | 6 ++++ 6 files changed, 101 insertions(+), 21 deletions(-) diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h index 5953ff2bd260..9eae419c7b18 100644 --- a/drivers/md/dm-core.h +++ b/drivers/md/dm-core.h @@ -114,6 +114,9 @@ struct mapped_device { bool init_tio_pdu:1; struct srcu_struct io_barrier; + + /* attach target via block-layer interposer */ + bool is_interposed; }; void disable_discard(struct mapped_device *md); diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index 5e306bba4375..2b4c9557c283 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1267,6 +1267,11 @@ static inline fmode_t get_mode(struct dm_ioctl *param) return mode; } +static inline bool get_interposer_flag(struct dm_ioctl *param) +{ + return (param->flags & DM_INTERPOSED_FLAG); +} + static int next_target(struct dm_target_spec *last, uint32_t next, void *end, struct dm_target_spec **spec, char **target_params) { @@ -1293,6 +1298,10 @@ static int populate_table(struct dm_table *table, DMWARN("populate_table: no targets specified"); return -EINVAL; } + if (table->md->is_interposed && (param->target_count != 1)) { + DMWARN("%s: with interposer should be specified only one target", __func__); + return -EINVAL; + } for (i = 0; i < param->target_count; i++) { @@ -1338,6 +1347,8 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si if (!md) return -ENXIO; + md->is_interposed = get_interposer_flag(param); + r = dm_table_create(&t, get_mode(param), param->target_count, md); if (r) goto err; @@ -2098,6 +2109,8 @@ int __init dm_early_create(struct dm_ioctl *dmi, if (r) goto err_hash_remove; + md->is_interposed = get_interposer_flag(dmi); + /* add targets */ for (i = 0; i < dmi->target_count; i++) { r = dm_table_add_target(t, spec_array[i]->target_type, diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 95391f78b8d5..f6e2eb3f8949 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -225,12 +225,13 @@ void dm_table_destroy(struct dm_table *t) /* * See if we've already got a device in the list. */ -static struct dm_dev_internal *find_device(struct list_head *l, dev_t dev) +static struct dm_dev_internal *find_device(struct list_head *l, dev_t dev, bool is_interposed) { struct dm_dev_internal *dd; list_for_each_entry (dd, l, list) - if (dd->dm_dev->bdev->bd_dev == dev) + if ((dd->dm_dev->bdev->bd_dev == dev) && + (dd->dm_dev->is_interposed == is_interposed)) return dd; return NULL; @@ -358,6 +359,18 @@ dev_t dm_get_dev_t(const char *path) } EXPORT_SYMBOL_GPL(dm_get_dev_t); +static inline void dm_disk_freeze(struct gendisk *disk) +{ + blk_mq_freeze_queue(disk->queue); + blk_mq_quiesce_queue(disk->queue); +} + +static inline void dm_disk_unfreeze(struct gendisk *disk) +{ + blk_mq_unquiesce_queue(disk->queue); + blk_mq_unfreeze_queue(disk->queue); +} + /* * Add a device to the list, or just increment the usage count if * it's already present. @@ -385,7 +398,7 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, return -ENODEV; } - dd = find_device(&t->devices, dev); + dd = find_device(&t->devices, dev, t->md->is_interposed); if (!dd) { dd = kmalloc(sizeof(*dd), GFP_KERNEL); if (!dd) @@ -398,15 +411,38 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, refcount_set(&dd->count, 1); list_add(&dd->list, &t->devices); - goto out; - } else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) { r = upgrade_mode(dd, mode, t->md); if (r) return r; + refcount_inc(&dd->count); } - refcount_inc(&dd->count); -out: + + if (t->md->is_interposed) { + struct block_device *original = dd->dm_dev->bdev; + struct block_device *interposer = t->md->disk->part0; + + if ((ti->begin != 0) || (ti->len < bdev_nr_sectors(original))) { + dm_put_device(ti, dd->dm_dev); + DMERR("The interposer device should not be less than the original."); + return -EINVAL; + } + + /* + * Attach mapped interposer device to original. + * It is quite convenient that device mapper creates + * one disk for one block device. + */ + dm_disk_freeze(original->bd_disk); + r = bdev_interposer_attach(original, interposer); + dm_disk_unfreeze(original->bd_disk); + if (r) { + dm_put_device(ti, dd->dm_dev); + DMERR("Failed to attach dm interposer."); + return r; + } + } + *result = dd->dm_dev; return 0; } @@ -446,6 +482,7 @@ void dm_put_device(struct dm_target *ti, struct dm_dev *d) { int found = 0; struct list_head *devices = &ti->table->devices; + struct mapped_device *md = ti->table->md; struct dm_dev_internal *dd; list_for_each_entry(dd, devices, list) { @@ -456,11 +493,17 @@ void dm_put_device(struct dm_target *ti, struct dm_dev *d) } if (!found) { DMWARN("%s: device %s not in table devices list", - dm_device_name(ti->table->md), d->name); + dm_device_name(md), d->name); return; } + if (md->is_interposed) { + dm_disk_freeze(d->bdev->bd_disk); + bdev_interposer_detach(d->bdev); + dm_disk_unfreeze(d->bdev->bd_disk); + } + if (refcount_dec_and_test(&dd->count)) { - dm_put_table_device(ti->table->md, d); + dm_put_table_device(md, d); list_del(&dd->list); kfree(dd); } diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 50b693d776d6..466bf70a66b0 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -762,16 +762,24 @@ static int open_table_device(struct table_device *td, dev_t dev, BUG_ON(td->dm_dev.bdev); - bdev = blkdev_get_by_dev(dev, td->dm_dev.mode | FMODE_EXCL, _dm_claim_ptr); - if (IS_ERR(bdev)) - return PTR_ERR(bdev); + if (md->is_interposed) { - r = bd_link_disk_holder(bdev, dm_disk(md)); - if (r) { - blkdev_put(bdev, td->dm_dev.mode | FMODE_EXCL); - return r; + bdev = blkdev_get_by_dev(dev, td->dm_dev.mode, NULL); + if (IS_ERR(bdev)) + return PTR_ERR(bdev); + } else { + bdev = blkdev_get_by_dev(dev, td->dm_dev.mode | FMODE_EXCL, _dm_claim_ptr); + if (IS_ERR(bdev)) + return PTR_ERR(bdev); + + r = bd_link_disk_holder(bdev, dm_disk(md)); + if (r) { + blkdev_put(bdev, td->dm_dev.mode | FMODE_EXCL); + return r; + } } + td->dm_dev.is_interposed = md->is_interposed; td->dm_dev.bdev = bdev; td->dm_dev.dax_dev = dax_get_by_host(bdev->bd_disk->disk_name); return 0; @@ -785,20 +793,26 @@ static void close_table_device(struct table_device *td, struct mapped_device *md if (!td->dm_dev.bdev) return; - bd_unlink_disk_holder(td->dm_dev.bdev, dm_disk(md)); - blkdev_put(td->dm_dev.bdev, td->dm_dev.mode | FMODE_EXCL); + if (td->dm_dev.is_interposed) + blkdev_put(td->dm_dev.bdev, td->dm_dev.mode); + else { + bd_unlink_disk_holder(td->dm_dev.bdev, dm_disk(md)); + blkdev_put(td->dm_dev.bdev, td->dm_dev.mode | FMODE_EXCL); + } put_dax(td->dm_dev.dax_dev); td->dm_dev.bdev = NULL; td->dm_dev.dax_dev = NULL; } static struct table_device *find_table_device(struct list_head *l, dev_t dev, - fmode_t mode) + fmode_t mode, bool is_interposed) { struct table_device *td; list_for_each_entry(td, l, list) - if (td->dm_dev.bdev->bd_dev == dev && td->dm_dev.mode == mode) + if (td->dm_dev.bdev->bd_dev == dev && + td->dm_dev.mode == mode && + td->dm_dev.is_interposed == is_interposed) return td; return NULL; @@ -811,7 +825,7 @@ int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode, struct table_device *td; mutex_lock(&md->table_devices_lock); - td = find_table_device(&md->table_devices, dev, mode); + td = find_table_device(&md->table_devices, dev, mode, md->is_interposed); if (!td) { td = kmalloc_node(sizeof(*td), GFP_KERNEL, md->numa_node_id); if (!td) { diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 7f4ac87c0b32..76a6dfb1cb29 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -159,6 +159,7 @@ struct dm_dev { struct block_device *bdev; struct dax_device *dax_dev; fmode_t mode; + bool is_interposed; char name[16]; }; diff --git a/include/uapi/linux/dm-ioctl.h b/include/uapi/linux/dm-ioctl.h index fcff6669137b..fc4d06bb3dbb 100644 --- a/include/uapi/linux/dm-ioctl.h +++ b/include/uapi/linux/dm-ioctl.h @@ -362,4 +362,10 @@ enum { */ #define DM_INTERNAL_SUSPEND_FLAG (1 << 18) /* Out */ +/* + * If set, the underlying device should open without FMODE_EXCL + * and attach mapped device via bdev_interposer. + */ +#define DM_INTERPOSED_FLAG (1 << 19) /* In */ + #endif /* _LINUX_DM_IOCTL_H */