target: Fix max_unmap_lba_count calc overflow

commit ea263c7fada4af8ec7fe5fcfd6e7d7705a89351b upstream.

max_discard_sectors only 32bits, and some non scsi backend
devices will set this to the max 0xffffffff, so we can end up
overflowing during the max_unmap_lba_count calculation.

This fixes a regression caused by my patch:

commit 8a9ebe717a133ba7bc90b06047f43cc6b8bcb8b3
Author: Mike Christie <mchristi@redhat.com>
Date:   Mon Jan 18 14:09:27 2016 -0600

    target: Fix WRITE_SAME/DISCARD conversion to linux 512b sectors

which can result in extra discards being sent to due the overflow
causing max_unmap_lba_count to be smaller than what the backing
device can actually support.

Signed-off-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index e366b812f0e14bd91c913633dc8827ca76f478ec..7c3ba7d711f1036e4bcb48bb06533e26b9ec01bf 100644 (file)
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -1583,13 +1583,15 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
  * in ATA and we need to set TPE=1
  */
 bool target_configure_unmap_from_queue(struct se_dev_attrib *attrib,
-                                      struct request_queue *q, int block_size)
+                                      struct request_queue *q)
 {
+       int block_size = queue_logical_block_size(q);
+
        if (!blk_queue_discard(q))
                return false;
 
-       attrib->max_unmap_lba_count = (q->limits.max_discard_sectors << 9) /
-                                                               block_size;
+       attrib->max_unmap_lba_count =
+               q->limits.max_discard_sectors >> (ilog2(block_size) - 9);
        /*
         * Currently hardcoded to 1 in Linux/SCSI code..
         */

diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index 6fe5b503f6e17c3c0e99e9432019b0e8b1e0d09b..d8bf1d9c723d9ba105ecd41e081d08e093c32573 100644 (file)
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -165,8 +165,7 @@ static int fd_configure_device(struct se_device *dev)
                        dev_size, div_u64(dev_size, fd_dev->fd_block_size),
                        fd_dev->fd_block_size);
 
-               if (target_configure_unmap_from_queue(&dev->dev_attrib, q,
-                                                     fd_dev->fd_block_size))
+               if (target_configure_unmap_from_queue(&dev->dev_attrib, q))
                        pr_debug("IFILE: BLOCK Discard support available,"
                                 " disabled by default\n");
                /*

diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index 357b9fb614990db3b38b8b200fed45ec28cb5c41..f66e677ee5e52edadd88f3e2fdf70a826d3cbe1e 100644 (file)
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -126,8 +126,7 @@ static int iblock_configure_device(struct se_device *dev)
        dev->dev_attrib.hw_max_sectors = queue_max_hw_sectors(q);
        dev->dev_attrib.hw_queue_depth = q->nr_requests;
 
-       if (target_configure_unmap_from_queue(&dev->dev_attrib, q,
-                                             dev->dev_attrib.hw_block_size))
+       if (target_configure_unmap_from_queue(&dev->dev_attrib, q))
                pr_debug("IBLOCK: BLOCK Discard support available,"
                         " disabled by default\n");
 

diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index 522ae25a61a700e67d3d6f472706ece534266308..c519c126ee14e2e74ec1d59866e0ef8ee562e7fa 100644 (file)
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -96,6 +96,6 @@ void  array_free(void *array, int n);
 
 sector_t target_to_linux_sector(struct se_device *dev, sector_t lb);
 bool target_configure_unmap_from_queue(struct se_dev_attrib *attrib,
-                                      struct request_queue *q, int block_size);
+                                      struct request_queue *q);
 
 #endif /* TARGET_CORE_BACKEND_H */