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: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 07425b8d606e7dd060746f57785f25153694b152..5638b60b419234d0126ad2c510e047e392a8f14d 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 703f885deac176e13116d9349187ad249fa29e04..03bfa49b55903ae312fde30d51e0fbae865aa327 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 91c625ac40d1d7d3b0a332a146dd9b04907282d5..7ee927d9c3ac070248f50690f45d51ea59ecbe0c 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 e006e10e08a979f07ecdbf75835b1a4c94997be3..a09a83603c52d43b7bad79b622959b7ebe95ed87 100644 (file)
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -97,6 +97,6 @@ sense_reason_t        transport_generic_map_mem_to_cmd(struct se_cmd *,
 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 */