tcmu: fix free block calculation

The blocks_left calculation does not account for free blocks
between 0 and thresh, so we could be queueing/waiting when
there are enough blocks free.

This has us add in the blocks between 0 and thresh as well as
at the end from thresh to DATA_BLOCK_BITS.

Signed-off-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 965f462eaa22dac3645116fcb89ae1a2bac70fbb..5d1daea5107905859943d3e3bef31d42f864ddc2 100644 (file)
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -637,7 +637,7 @@ static void gather_data_area(struct tcmu_dev *udev, struct tcmu_cmd *cmd,
 
 static inline size_t spc_bitmap_free(unsigned long *bitmap, uint32_t thresh)
 {
-       return DATA_BLOCK_SIZE * (thresh - bitmap_weight(bitmap, thresh));
+       return thresh - bitmap_weight(bitmap, thresh);
 }
 
 /*
@@ -677,8 +677,9 @@ static bool is_ring_space_avail(struct tcmu_dev *udev, struct tcmu_cmd *cmd,
 
        /* try to check and get the data blocks as needed */
        space = spc_bitmap_free(udev->data_bitmap, udev->dbi_thresh);
-       if (space < data_needed) {
-               unsigned long blocks_left = DATA_BLOCK_BITS - udev->dbi_thresh;
+       if ((space * DATA_BLOCK_SIZE) < data_needed) {
+               unsigned long blocks_left = DATA_BLOCK_BITS - udev->dbi_thresh +
+                                               space;
                unsigned long grow;
 
                if (blocks_left < blocks_needed) {