summaryrefslogtreecommitdiff
path: root/block/holder.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2021-08-30 18:52:11 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-08-30 18:52:11 -0700
commit679369114e55f422dc593d0628cfde1d04ae59b3 (patch)
tree7eb717f5ee39e8a4035d3b03da5a7f26643405af /block/holder.c
parent8596e589b787732c8346f0482919e83cc9362db1 (diff)
parent1d1cf156dc176e30eeaced5cf1450d582d387b81 (diff)
Merge tag 'for-5.15/block-2021-08-30' of git://git.kernel.dk/linux-block
Pull block updates from Jens Axboe: "Nothing major in here - lots of good cleanups and tech debt handling, which is also evident in the diffstats. In particular: - Add disk sequence numbers (Matteo) - Discard merge fix (Ming) - Relax disk zoned reporting restrictions (Niklas) - Bio error handling zoned leak fix (Pavel) - Start of proper add_disk() error handling (Luis, Christoph) - blk crypto fix (Eric) - Non-standard GPT location support (Dmitry) - IO priority improvements and cleanups (Damien)o - blk-throtl improvements (Chunguang) - diskstats_show() stack reduction (Abd-Alrhman) - Loop scheduler selection (Bart) - Switch block layer to use kmap_local_page() (Christoph) - Remove obsolete disk_name helper (Christoph) - block_device refcounting improvements (Christoph) - Ensure gendisk always has a request queue reference (Christoph) - Misc fixes/cleanups (Shaokun, Oliver, Guoqing)" * tag 'for-5.15/block-2021-08-30' of git://git.kernel.dk/linux-block: (129 commits) sg: pass the device name to blk_trace_setup block, bfq: cleanup the repeated declaration blk-crypto: fix check for too-large dun_bytes blk-zoned: allow BLKREPORTZONE without CAP_SYS_ADMIN blk-zoned: allow zone management send operations without CAP_SYS_ADMIN block: mark blkdev_fsync static block: refine the disk_live check in del_gendisk mmc: sdhci-tegra: Enable MMC_CAP2_ALT_GPT_TEGRA mmc: block: Support alternative_gpt_sector() operation partitions/efi: Support non-standard GPT location block: Add alternative_gpt_sector() operation bio: fix page leak bio_add_hw_page failure block: remove CONFIG_DEBUG_BLOCK_EXT_DEVT block: remove a pointless call to MINOR() in device_add_disk null_blk: add error handling support for add_disk() virtio_blk: add error handling support for add_disk() block: add error handling for device_add_disk / add_disk block: return errors from disk_alloc_events block: return errors from blk_integrity_add block: call blk_register_queue earlier in device_add_disk ...
Diffstat (limited to 'block/holder.c')
-rw-r--r--block/holder.c174
1 files changed, 174 insertions, 0 deletions
diff --git a/block/holder.c b/block/holder.c
new file mode 100644
index 000000000000..9dc084182337
--- /dev/null
+++ b/block/holder.c
@@ -0,0 +1,174 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/genhd.h>
+
+struct bd_holder_disk {
+ struct list_head list;
+ struct block_device *bdev;
+ int refcnt;
+};
+
+static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
+ struct gendisk *disk)
+{
+ struct bd_holder_disk *holder;
+
+ list_for_each_entry(holder, &disk->slave_bdevs, list)
+ if (holder->bdev == bdev)
+ return holder;
+ return NULL;
+}
+
+static int add_symlink(struct kobject *from, struct kobject *to)
+{
+ return sysfs_create_link(from, to, kobject_name(to));
+}
+
+static void del_symlink(struct kobject *from, struct kobject *to)
+{
+ sysfs_remove_link(from, kobject_name(to));
+}
+
+static int __link_disk_holder(struct block_device *bdev, struct gendisk *disk)
+{
+ int ret;
+
+ ret = add_symlink(disk->slave_dir, bdev_kobj(bdev));
+ if (ret)
+ return ret;
+ ret = add_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
+ if (ret)
+ del_symlink(disk->slave_dir, bdev_kobj(bdev));
+ return ret;
+}
+
+/**
+ * bd_link_disk_holder - create symlinks between holding disk and slave bdev
+ * @bdev: the claimed slave bdev
+ * @disk: the holding disk
+ *
+ * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
+ *
+ * This functions creates the following sysfs symlinks.
+ *
+ * - from "slaves" directory of the holder @disk to the claimed @bdev
+ * - from "holders" directory of the @bdev to the holder @disk
+ *
+ * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
+ * passed to bd_link_disk_holder(), then:
+ *
+ * /sys/block/dm-0/slaves/sda --> /sys/block/sda
+ * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
+ *
+ * The caller must have claimed @bdev before calling this function and
+ * ensure that both @bdev and @disk are valid during the creation and
+ * lifetime of these symlinks.
+ *
+ * CONTEXT:
+ * Might sleep.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
+{
+ struct bd_holder_disk *holder;
+ int ret = 0;
+
+ mutex_lock(&disk->open_mutex);
+
+ WARN_ON_ONCE(!bdev->bd_holder);
+
+ /* FIXME: remove the following once add_disk() handles errors */
+ if (WARN_ON(!bdev->bd_holder_dir))
+ goto out_unlock;
+
+ holder = bd_find_holder_disk(bdev, disk);
+ if (holder) {
+ holder->refcnt++;
+ goto out_unlock;
+ }
+
+ holder = kzalloc(sizeof(*holder), GFP_KERNEL);
+ if (!holder) {
+ ret = -ENOMEM;
+ goto out_unlock;
+ }
+
+ INIT_LIST_HEAD(&holder->list);
+ holder->bdev = bdev;
+ holder->refcnt = 1;
+ if (disk->slave_dir) {
+ ret = __link_disk_holder(bdev, disk);
+ if (ret) {
+ kfree(holder);
+ goto out_unlock;
+ }
+ }
+
+ list_add(&holder->list, &disk->slave_bdevs);
+ /*
+ * del_gendisk drops the initial reference to bd_holder_dir, so we need
+ * to keep our own here to allow for cleanup past that point.
+ */
+ kobject_get(bdev->bd_holder_dir);
+
+out_unlock:
+ mutex_unlock(&disk->open_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(bd_link_disk_holder);
+
+static void __unlink_disk_holder(struct block_device *bdev,
+ struct gendisk *disk)
+{
+ del_symlink(disk->slave_dir, bdev_kobj(bdev));
+ del_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
+}
+
+/**
+ * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
+ * @bdev: the calimed slave bdev
+ * @disk: the holding disk
+ *
+ * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
+ *
+ * CONTEXT:
+ * Might sleep.
+ */
+void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
+{
+ struct bd_holder_disk *holder;
+
+ mutex_lock(&disk->open_mutex);
+ holder = bd_find_holder_disk(bdev, disk);
+ if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
+ if (disk->slave_dir)
+ __unlink_disk_holder(bdev, disk);
+ kobject_put(bdev->bd_holder_dir);
+ list_del_init(&holder->list);
+ kfree(holder);
+ }
+ mutex_unlock(&disk->open_mutex);
+}
+EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
+
+int bd_register_pending_holders(struct gendisk *disk)
+{
+ struct bd_holder_disk *holder;
+ int ret;
+
+ mutex_lock(&disk->open_mutex);
+ list_for_each_entry(holder, &disk->slave_bdevs, list) {
+ ret = __link_disk_holder(holder->bdev, disk);
+ if (ret)
+ goto out_undo;
+ }
+ mutex_unlock(&disk->open_mutex);
+ return 0;
+
+out_undo:
+ list_for_each_entry_continue_reverse(holder, &disk->slave_bdevs, list)
+ __unlink_disk_holder(holder->bdev, disk);
+ mutex_unlock(&disk->open_mutex);
+ return ret;
+}
generated by cgit (git 2.34.1) at 2025-03-26 15:14:21 +0000