quoted hunk ↗ jump to hunk
+static blk_qc_t __submit_bio_interposed(struct bio *bio)
+{
+ struct bio_list bio_list[2] = { };
+ blk_qc_t ret = BLK_QC_T_NONE;
+
+ current->bio_list = bio_list;
+ if (likely(bio_queue_enter(bio) == 0)) {
+ struct block_device *bdev = bio->bi_bdev;
+
+ if (likely(bdev_has_interposer(bdev))) {
+ bio_set_flag(bio, BIO_INTERPOSED);
+ bdev->bd_interposer->ip_submit_bio(bio);
+ } else {
+ /* interposer was removed */
+ bio_list_add(¤t->bio_list[0], bio);
+ }
+
+ blk_queue_exit(bdev->bd_disk->queue);
+ }
+ current->bio_list = NULL;
+
+ /* Resubmit remaining bios */
+ while ((bio = bio_list_pop(&bio_list[0])))
+ ret = submit_bio_noacct(bio);
+
+ return ret;
+}
+
/**
* submit_bio_noacct - re-submit a bio to the block device layer for I/O
* @bio: The bio describing the location in memory and on the device.@@ -1043,6 +1071,14 @@ blk_qc_t submit_bio_noacct(struct bio *bio)
return BLK_QC_T_NONE;
}
+ /*
+ * Checking the BIO_INTERPOSED flag is necessary so that the bio
+ * created by the bdev_interposer do not get to it for processing.
+ */
+ if (bdev_has_interposer(bio->bi_bdev) &&
+ !bio_flagged(bio, BIO_INTERPOSED))
+ return __submit_bio_interposed(bio);
+
if (!bio->bi_bdev->bd_disk->fops->submit_bio)
return __submit_bio_noacct_mq(bio);
return __submit_bio_noacct(bio);
diff --git a/block/genhd.c b/block/genhd.c
index fcc530164b5a..1ae8516643c8 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -30,6 +30,11 @@
static struct kobject *block_depr;
DECLARE_RWSEM(bdev_lookup_sem);
+/*
+ * Prevents different block-layer interposers from attaching or detaching
+ * to the block device at the same time.
+ */
+DEFINE_MUTEX(bdev_interposer_attach_lock);
This one can and should be marked static.
+int bdev_interposer_attach(struct block_device *bdev, struct bdev_interposer *interposer,
Please avoid the overly long line.
quoted hunk ↗ jump to hunk
+ int ret = 0;
+
+ if (WARN_ON(!interposer))
WARN_ON_ONCE?
quoted hunk ↗ jump to hunk
+ return -EINVAL;
+
+ if (!blk_mq_is_queue_frozen(bdev->bd_disk->queue))
+ return -EPERM;
This probly should be a WARN_ON_ONCE() as well.
quoted hunk ↗ jump to hunk
+
+ mutex_lock(&bdev_interposer_attach_lock);
+ if (bdev_has_interposer(bdev)) {
+ if (bdev->bd_interposer->ip_submit_bio == ip_submit_bio)
+ ret = -EALREADY;
+ else
+ ret = -EBUSY;
+ goto out;
+ }
Do we really need the two different error codes here?
+
+ interposer->ip_submit_bio = ip_submit_bio;
I'd rather let the caller initialize the field instead of passing the
submit function separately.
quoted hunk ↗ jump to hunk
+void bdev_interposer_detach(struct bdev_interposer *interposer,
+ const ip_submit_bio_t ip_submit_bio)
+{
quoted hunk ↗ jump to hunk
+ /* Check if it is really our interposer. */
+ if (WARN_ON(bdev->bd_interposer->ip_submit_bio != ip_submit_bio))
+ goto out;
I don't really see any need to pass ip_submit_bio just for this check.
+ struct bdev_interposer * bd_interposer;
The * goes just before the member name.
quoted hunk ↗ jump to hunk
+/*
+ * block layer interposers structure and functions
+ */
+typedef void (*ip_submit_bio_t) (struct bio *bio);
+
+struct bdev_interposer {
+ ip_submit_bio_t ip_submit_bio;
+ struct block_device *bdev;
Do we need the ip_ prefix here? Also we probably don't really the
the typedef for the function pointer.
+#define bdev_has_interposer(bd) ((bd)->bd_interposer != NULL)
And inline function would be nice here.