Update for 2.6.39

git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@3462 d57e44dd-8a1f-0410-8b47-8ef2f437770f
2026-05-19 03:31:26 +00:00 · 2011-05-20 00:52:34 +00:00
parent 3a2ba412c3
commit b5a41deb28
7 changed files with 1021 additions and 18 deletions
--- a/iscsi-scst/kernel/patches/put_page_callback-2.6.39.patch
+++ b/iscsi-scst/kernel/patches/put_page_callback-2.6.39.patch
@@ -0,0 +1,390 @@
+diff -upkr linux-2.6.39/include/linux/mm_types.h linux-2.6.39/include/linux/mm_types.h
+--- linux-2.6.39/include/linux/mm_types.h	2011-05-19 00:06:34.000000000 -0400
+++ linux-2.6.39/include/linux/mm_types.h	2011-05-19 10:46:24.669812999 -0400
+@@ -100,6 +100,18 @@ struct page {
+ 	 */
+ 	void *shadow;
+ #endif
+
+#if defined(CONFIG_TCP_ZERO_COPY_TRANSFER_COMPLETION_NOTIFICATION)
+	/*
+	 * Used to implement support for notification on zero-copy TCP transfer
+	 * completion. It might look as not good to have this field here and
+	 * it's better to have it in struct sk_buff, but it would make the code
+	 * much more complicated and fragile, since all skb then would have to
+	 * contain only pages with the same value in this field.
+	 */
+	 void *net_priv;
+#endif
+
+ };
+ 
+ /*
+diff -upkr linux-2.6.39/include/linux/net.h linux-2.6.39/include/linux/net.h
+--- linux-2.6.39/include/linux/net.h	2011-05-19 00:06:34.000000000 -0400
+++ linux-2.6.39/include/linux/net.h	2011-05-19 10:46:24.669812999 -0400
+@@ -60,6 +60,7 @@ typedef enum {
+ #include <linux/fcntl.h>	/* For O_CLOEXEC and O_NONBLOCK */
+ #include <linux/kmemcheck.h>
+ #include <linux/rcupdate.h>
+#include <linux/mm.h>
+ 
+ struct poll_table_struct;
+ struct pipe_inode_info;
+@@ -294,5 +295,44 @@ extern int kernel_sock_shutdown(struct s
+ extern struct ratelimit_state net_ratelimit_state;
+ #endif
+ 
+#if defined(CONFIG_TCP_ZERO_COPY_TRANSFER_COMPLETION_NOTIFICATION)
+/* Support for notification on zero-copy TCP transfer completion */
+typedef void (*net_get_page_callback_t)(struct page *page);
+typedef void (*net_put_page_callback_t)(struct page *page);
+
+extern net_get_page_callback_t net_get_page_callback;
+extern net_put_page_callback_t net_put_page_callback;
+
+extern int net_set_get_put_page_callbacks(
+	net_get_page_callback_t get_callback,
+	net_put_page_callback_t put_callback);
+
+/*
+ * See comment for net_set_get_put_page_callbacks() why those functions
+ * don't need any protection.
+ */
+static inline void net_get_page(struct page *page)
+{
+	if (page->net_priv != 0)
+		net_get_page_callback(page);
+	get_page(page);
+}
+static inline void net_put_page(struct page *page)
+{
+	if (page->net_priv != 0)
+		net_put_page_callback(page);
+	put_page(page);
+}
+#else
+static inline void net_get_page(struct page *page)
+{
+	get_page(page);
+}
+static inline void net_put_page(struct page *page)
+{
+	put_page(page);
+}
+#endif /* CONFIG_TCP_ZERO_COPY_TRANSFER_COMPLETION_NOTIFICATION */
+
+ #endif /* __KERNEL__ */
+ #endif	/* _LINUX_NET_H */
+diff -upkr linux-2.6.39/net/core/dev.c linux-2.6.39/net/core/dev.c
+--- linux-2.6.39/net/core/dev.c	2011-05-19 00:06:34.000000000 -0400
+++ linux-2.6.39/net/core/dev.c	2011-05-19 10:46:24.669812999 -0400
+@@ -3418,7 +3418,7 @@ pull:
+ 		skb_shinfo(skb)->frags[0].size -= grow;
+ 
+ 		if (unlikely(!skb_shinfo(skb)->frags[0].size)) {
+-			put_page(skb_shinfo(skb)->frags[0].page);
+			net_put_page(skb_shinfo(skb)->frags[0].page);
+ 			memmove(skb_shinfo(skb)->frags,
+ 				skb_shinfo(skb)->frags + 1,
+ 				--skb_shinfo(skb)->nr_frags * sizeof(skb_frag_t));
+diff -upkr linux-2.6.39/net/core/skbuff.c linux-2.6.39/net/core/skbuff.c
+--- linux-2.6.39/net/core/skbuff.c	2011-05-19 00:06:34.000000000 -0400
+++ linux-2.6.39/net/core/skbuff.c	2011-05-19 10:46:24.669812999 -0400
+@@ -76,13 +76,13 @@ static struct kmem_cache *skbuff_fclone_
+ static void sock_pipe_buf_release(struct pipe_inode_info *pipe,
+ 				  struct pipe_buffer *buf)
+ {
+-	put_page(buf->page);
+	net_put_page(buf->page);
+ }
+ 
+ static void sock_pipe_buf_get(struct pipe_inode_info *pipe,
+ 				struct pipe_buffer *buf)
+ {
+-	get_page(buf->page);
+	net_get_page(buf->page);
+ }
+ 
+ static int sock_pipe_buf_steal(struct pipe_inode_info *pipe,
+@@ -325,7 +325,7 @@ static void skb_release_data(struct sk_b
+ 		if (skb_shinfo(skb)->nr_frags) {
+ 			int i;
+ 			for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
+-				put_page(skb_shinfo(skb)->frags[i].page);
+				net_put_page(skb_shinfo(skb)->frags[i].page);
+ 		}
+ 
+ 		if (skb_has_frag_list(skb))
+@@ -732,7 +732,7 @@ struct sk_buff *pskb_copy(struct sk_buff
+ 
+ 		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+ 			skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
+-			get_page(skb_shinfo(n)->frags[i].page);
+			net_get_page(skb_shinfo(n)->frags[i].page);
+ 		}
+ 		skb_shinfo(n)->nr_frags = i;
+ 	}
+@@ -819,7 +819,7 @@ int pskb_expand_head(struct sk_buff *skb
+ 		kfree(skb->head);
+ 	} else {
+ 		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
+-			get_page(skb_shinfo(skb)->frags[i].page);
+			net_get_page(skb_shinfo(skb)->frags[i].page);
+ 
+ 		if (skb_has_frag_list(skb))
+ 			skb_clone_fraglist(skb);
+@@ -1097,7 +1097,7 @@ drop_pages:
+ 		skb_shinfo(skb)->nr_frags = i;
+ 
+ 		for (; i < nfrags; i++)
+-			put_page(skb_shinfo(skb)->frags[i].page);
+			net_put_page(skb_shinfo(skb)->frags[i].page);
+ 
+ 		if (skb_has_frag_list(skb))
+ 			skb_drop_fraglist(skb);
+@@ -1266,7 +1266,7 @@ pull_pages:
+ 	k = 0;
+ 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+ 		if (skb_shinfo(skb)->frags[i].size <= eat) {
+-			put_page(skb_shinfo(skb)->frags[i].page);
+			net_put_page(skb_shinfo(skb)->frags[i].page);
+ 			eat -= skb_shinfo(skb)->frags[i].size;
+ 		} else {
+ 			skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
+@@ -1367,7 +1367,7 @@ EXPORT_SYMBOL(skb_copy_bits);
+  */
+ static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
+ {
+-	put_page(spd->pages[i]);
+	net_put_page(spd->pages[i]);
+ }
+ 
+ static inline struct page *linear_to_page(struct page *page, unsigned int *len,
+@@ -1391,7 +1391,7 @@ new_page:
+ 		off = sk->sk_sndmsg_off;
+ 		mlen = PAGE_SIZE - off;
+ 		if (mlen < 64 && mlen < *len) {
+-			put_page(p);
+			net_put_page(p);
+ 			goto new_page;
+ 		}
+ 
+@@ -1401,7 +1401,7 @@ new_page:
+ 	memcpy(page_address(p) + off, page_address(page) + *offset, *len);
+ 	sk->sk_sndmsg_off += *len;
+ 	*offset = off;
+-	get_page(p);
+	net_get_page(p);
+ 
+ 	return p;
+ }
+@@ -1423,7 +1423,7 @@ static inline int spd_fill_page(struct s
+ 		if (!page)
+ 			return 1;
+ 	} else
+-		get_page(page);
+		net_get_page(page);
+ 
+ 	spd->pages[spd->nr_pages] = page;
+ 	spd->partial[spd->nr_pages].len = *len;
+@@ -2056,7 +2056,7 @@ static inline void skb_split_no_header(s
+ 				 *    where splitting is expensive.
+ 				 * 2. Split is accurately. We make this.
+ 				 */
+-				get_page(skb_shinfo(skb)->frags[i].page);
+				net_get_page(skb_shinfo(skb)->frags[i].page);
+ 				skb_shinfo(skb1)->frags[0].page_offset += len - pos;
+ 				skb_shinfo(skb1)->frags[0].size -= len - pos;
+ 				skb_shinfo(skb)->frags[i].size	= len - pos;
+@@ -2178,7 +2178,7 @@ int skb_shift(struct sk_buff *tgt, struc
+ 			to++;
+ 
+ 		} else {
+-			get_page(fragfrom->page);
+			net_get_page(fragfrom->page);
+ 			fragto->page = fragfrom->page;
+ 			fragto->page_offset = fragfrom->page_offset;
+ 			fragto->size = todo;
+@@ -2200,7 +2200,7 @@ int skb_shift(struct sk_buff *tgt, struc
+ 		fragto = &skb_shinfo(tgt)->frags[merge];
+ 
+ 		fragto->size += fragfrom->size;
+-		put_page(fragfrom->page);
+		net_put_page(fragfrom->page);
+ 	}
+ 
+ 	/* Reposition in the original skb */
+@@ -2598,7 +2598,7 @@ struct sk_buff *skb_segment(struct sk_bu
+ 
+ 		while (pos < offset + len && i < nfrags) {
+ 			*frag = skb_shinfo(skb)->frags[i];
+-			get_page(frag->page);
+			net_get_page(frag->page);
+ 			size = frag->size;
+ 
+ 			if (pos < offset) {
+diff -upkr linux-2.6.39/net/ipv4/ip_output.c linux-2.6.39/net/ipv4/ip_output.c
+--- linux-2.6.39/net/ipv4/ip_output.c	2011-05-19 00:06:34.000000000 -0400
+++ linux-2.6.39/net/ipv4/ip_output.c	2011-05-19 10:47:39.565813000 -0400
+@@ -985,7 +985,7 @@ alloc_new_skb:
+ 						err = -EMSGSIZE;
+ 						goto error;
+ 					}
+-					get_page(page);
+					net_get_page(page);
+ 					skb_fill_page_desc(skb, i, page, off, 0);
+ 					frag = &skb_shinfo(skb)->frags[i];
+ 				}
+@@ -1220,7 +1220,7 @@ ssize_t	ip_append_page(struct sock *sk, 
+ 		if (skb_can_coalesce(skb, i, page, offset)) {
+ 			skb_shinfo(skb)->frags[i-1].size += len;
+ 		} else if (i < MAX_SKB_FRAGS) {
+-			get_page(page);
+			net_get_page(page);
+ 			skb_fill_page_desc(skb, i, page, offset, len);
+ 		} else {
+ 			err = -EMSGSIZE;
+diff -upkr linux-2.6.39/net/ipv4/Makefile linux-2.6.39/net/ipv4/Makefile
+--- linux-2.6.39/net/ipv4/Makefile	2011-05-19 00:06:34.000000000 -0400
+++ linux-2.6.39/net/ipv4/Makefile	2011-05-19 10:46:24.669812999 -0400
+@@ -48,6 +48,7 @@ obj-$(CONFIG_TCP_CONG_LP) += tcp_lp.o
+ obj-$(CONFIG_TCP_CONG_YEAH) += tcp_yeah.o
+ obj-$(CONFIG_TCP_CONG_ILLINOIS) += tcp_illinois.o
+ obj-$(CONFIG_NETLABEL) += cipso_ipv4.o
+obj-$(CONFIG_TCP_ZERO_COPY_TRANSFER_COMPLETION_NOTIFICATION) += tcp_zero_copy.o
+ 
+ obj-$(CONFIG_XFRM) += xfrm4_policy.o xfrm4_state.o xfrm4_input.o \
+ 		      xfrm4_output.o
+diff -upkr linux-2.6.39/net/ipv4/tcp.c linux-2.6.39/net/ipv4/tcp.c
+--- linux-2.6.39/net/ipv4/tcp.c	2011-05-19 00:06:34.000000000 -0400
+++ linux-2.6.39/net/ipv4/tcp.c	2011-05-19 10:46:24.673813002 -0400
+@@ -815,7 +815,7 @@ new_segment:
+ 		if (can_coalesce) {
+ 			skb_shinfo(skb)->frags[i - 1].size += copy;
+ 		} else {
+-			get_page(page);
+			net_get_page(page);
+ 			skb_fill_page_desc(skb, i, page, offset, copy);
+ 		}
+ 
+@@ -1021,7 +1021,7 @@ new_segment:
+ 					goto new_segment;
+ 				} else if (page) {
+ 					if (off == PAGE_SIZE) {
+-						put_page(page);
+						net_put_page(page);
+ 						TCP_PAGE(sk) = page = NULL;
+ 						off = 0;
+ 					}
+@@ -1062,9 +1062,9 @@ new_segment:
+ 				} else {
+ 					skb_fill_page_desc(skb, i, page, off, copy);
+ 					if (TCP_PAGE(sk)) {
+-						get_page(page);
+						net_get_page(page);
+ 					} else if (off + copy < PAGE_SIZE) {
+-						get_page(page);
+						net_get_page(page);
+ 						TCP_PAGE(sk) = page;
+ 					}
+ 				}
+diff -upkr linux-2.6.39/net/ipv4/tcp_output.c linux-2.6.39/net/ipv4/tcp_output.c
+--- linux-2.6.39/net/ipv4/tcp_output.c	2011-05-19 00:06:34.000000000 -0400
+++ linux-2.6.39/net/ipv4/tcp_output.c	2011-05-19 10:46:24.673813002 -0400
+@@ -1095,7 +1095,7 @@ static void __pskb_trim_head(struct sk_b
+ 	k = 0;
+ 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+ 		if (skb_shinfo(skb)->frags[i].size <= eat) {
+-			put_page(skb_shinfo(skb)->frags[i].page);
+			net_put_page(skb_shinfo(skb)->frags[i].page);
+ 			eat -= skb_shinfo(skb)->frags[i].size;
+ 		} else {
+ 			skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
+diff -upkr linux-2.6.39/net/ipv4/tcp_zero_copy.c linux-2.6.39/net/ipv4/tcp_zero_copy.c
+--- linux-2.6.39/net/ipv4/tcp_zero_copy.c	2011-05-19 10:44:53.685813002 -0400
+++ linux-2.6.39/net/ipv4/tcp_zero_copy.c	2011-05-19 10:46:24.673813002 -0400
+@@ -0,0 +1,49 @@
+/*
+ *	Support routines for TCP zero copy transmit
+ *
+ *	Created by Vladislav Bolkhovitin
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      version 2 as published by the Free Software Foundation.
+ */
+
+#include <linux/skbuff.h>
+
+net_get_page_callback_t net_get_page_callback __read_mostly;
+EXPORT_SYMBOL(net_get_page_callback);
+
+net_put_page_callback_t net_put_page_callback __read_mostly;
+EXPORT_SYMBOL(net_put_page_callback);
+
+/*
+ * Caller of this function must ensure that at the moment when it's called
+ * there are no pages in the system with net_priv field set to non-zero
+ * value. Hence, this function, as well as net_get_page() and net_put_page(),
+ * don't need any protection.
+ */
+int net_set_get_put_page_callbacks(
+	net_get_page_callback_t get_callback,
+	net_put_page_callback_t put_callback)
+{
+	int res = 0;
+
+	if ((net_get_page_callback != NULL) && (get_callback != NULL) &&
+	    (net_get_page_callback != get_callback)) {
+		res = -EBUSY;
+		goto out;
+	}
+
+	if ((net_put_page_callback != NULL) && (put_callback != NULL) &&
+	    (net_put_page_callback != put_callback)) {
+		res = -EBUSY;
+		goto out;
+	}
+
+	net_get_page_callback = get_callback;
+	net_put_page_callback = put_callback;
+
+out:
+	return res;
+}
+EXPORT_SYMBOL(net_set_get_put_page_callbacks);
+diff -upkr linux-2.6.39/net/ipv6/ip6_output.c linux-2.6.39/net/ipv6/ip6_output.c
+--- linux-2.6.39/net/ipv6/ip6_output.c	2011-05-19 00:06:34.000000000 -0400
+++ linux-2.6.39/net/ipv6/ip6_output.c	2011-05-19 10:46:24.673813002 -0400
+@@ -1444,7 +1444,7 @@ alloc_new_skb:
+ 						err = -EMSGSIZE;
+ 						goto error;
+ 					}
+-					get_page(page);
+					net_get_page(page);
+ 					skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0);
+ 					frag = &skb_shinfo(skb)->frags[i];
+ 				}
+diff -upkr linux-2.6.39/net/Kconfig linux-2.6.39/net/Kconfig
+--- linux-2.6.39/net/Kconfig	2011-05-19 00:06:34.000000000 -0400
+++ linux-2.6.39/net/Kconfig	2011-05-19 10:46:24.673813002 -0400
+@@ -72,6 +72,18 @@ config INET
+ 
+ 	  Short answer: say Y.
+ 
+config TCP_ZERO_COPY_TRANSFER_COMPLETION_NOTIFICATION
+	bool "TCP/IP zero-copy transfer completion notification"
+        depends on INET
+        default SCST_ISCSI
+	---help---
+	  Adds support for sending a notification upon completion of a
+          zero-copy TCP/IP transfer. This can speed up certain TCP/IP
+          software. Currently this is only used by the iSCSI target driver
+          iSCSI-SCST.
+
+          If unsure, say N.
+
+ if INET
+ source "net/ipv4/Kconfig"
+ source "net/ipv6/Kconfig"
--- a/qla2x00t/qla_mid.c
+++ b/qla2x00t/qla_mid.c
@@ -9,7 +9,6 @@
 #include <linux/version.h>
 #include <linux/moduleparam.h>
 #include <linux/vmalloc.h>
-#include <linux/smp_lock.h>
 #include <linux/list.h>

 #include <scsi/scsi_tcq.h>
--- a/scst/kernel/scst_exec_req_fifo-2.6.39.patch
+++ b/scst/kernel/scst_exec_req_fifo-2.6.39.patch
@@ -0,0 +1,532 @@
+diff -upkr linux-2.6.39/block/blk-map.c linux-2.6.39/block/blk-map.c
+--- linux-2.6.39/block/blk-map.c	2011-05-19 00:06:34.000000000 -0400
+++ linux-2.6.39/block/blk-map.c	2011-05-19 10:49:02.753812997 -0400
+@@ -5,6 +5,8 @@
+ #include <linux/module.h>
+ #include <linux/bio.h>
+ #include <linux/blkdev.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+ #include <scsi/sg.h>		/* for struct sg_iovec */
+ 
+ #include "blk.h"
+@@ -274,6 +276,339 @@ int blk_rq_unmap_user(struct bio *bio)
+ }
+ EXPORT_SYMBOL(blk_rq_unmap_user);
+ 
+struct blk_kern_sg_work {
+	atomic_t bios_inflight;
+	struct sg_table sg_table;
+	struct scatterlist *src_sgl;
+};
+
+static void blk_free_kern_sg_work(struct blk_kern_sg_work *bw)
+{
+	struct sg_table *sgt = &bw->sg_table;
+	struct scatterlist *sg;
+	int i;
+
+	for_each_sg(sgt->sgl, sg, sgt->orig_nents, i) {
+		struct page *pg = sg_page(sg);
+		if (pg == NULL)
+			break;
+		__free_page(pg);
+	}
+
+	sg_free_table(sgt);
+	kfree(bw);
+	return;
+}
+
+static void blk_bio_map_kern_endio(struct bio *bio, int err)
+{
+	struct blk_kern_sg_work *bw = bio->bi_private;
+
+	if (bw != NULL) {
+		/* Decrement the bios in processing and, if zero, free */
+		BUG_ON(atomic_read(&bw->bios_inflight) <= 0);
+		if (atomic_dec_and_test(&bw->bios_inflight)) {
+			if ((bio_data_dir(bio) == READ) && (err == 0)) {
+				unsigned long flags;
+
+				local_irq_save(flags);	/* to protect KMs */
+				sg_copy(bw->src_sgl, bw->sg_table.sgl, 0, 0,
+					KM_BIO_DST_IRQ, KM_BIO_SRC_IRQ);
+				local_irq_restore(flags);
+			}
+			blk_free_kern_sg_work(bw);
+		}
+	}
+
+	bio_put(bio);
+	return;
+}
+
+static int blk_rq_copy_kern_sg(struct request *rq, struct scatterlist *sgl,
+			       int nents, struct blk_kern_sg_work **pbw,
+			       gfp_t gfp, gfp_t page_gfp)
+{
+	int res = 0, i;
+	struct scatterlist *sg;
+	struct scatterlist *new_sgl;
+	int new_sgl_nents;
+	size_t len = 0, to_copy;
+	struct blk_kern_sg_work *bw;
+
+	bw = kzalloc(sizeof(*bw), gfp);
+	if (bw == NULL)
+		goto out;
+
+	bw->src_sgl = sgl;
+
+	for_each_sg(sgl, sg, nents, i)
+		len += sg->length;
+	to_copy = len;
+
+	new_sgl_nents = PFN_UP(len);
+
+	res = sg_alloc_table(&bw->sg_table, new_sgl_nents, gfp);
+	if (res != 0)
+		goto err_free;
+
+	new_sgl = bw->sg_table.sgl;
+
+	for_each_sg(new_sgl, sg, new_sgl_nents, i) {
+		struct page *pg;
+
+		pg = alloc_page(page_gfp);
+		if (pg == NULL)
+			goto err_free;
+
+		sg_assign_page(sg, pg);
+		sg->length = min_t(size_t, PAGE_SIZE, len);
+
+		len -= PAGE_SIZE;
+	}
+
+	if (rq_data_dir(rq) == WRITE) {
+		/*
+		 * We need to limit amount of copied data to to_copy, because
+		 * sgl might have the last element in sgl not marked as last in
+		 * SG chaining.
+		 */
+		sg_copy(new_sgl, sgl, 0, to_copy,
+			KM_USER0, KM_USER1);
+	}
+
+	*pbw = bw;
+	/*
+	 * REQ_COPY_USER name is misleading. It should be something like
+	 * REQ_HAS_TAIL_SPACE_FOR_PADDING.
+	 */
+	rq->cmd_flags |= REQ_COPY_USER;
+
+out:
+	return res;
+
+err_free:
+	blk_free_kern_sg_work(bw);
+	res = -ENOMEM;
+	goto out;
+}
+
+static int __blk_rq_map_kern_sg(struct request *rq, struct scatterlist *sgl,
+	int nents, struct blk_kern_sg_work *bw, gfp_t gfp)
+{
+	int res;
+	struct request_queue *q = rq->q;
+	int rw = rq_data_dir(rq);
+	int max_nr_vecs, i;
+	size_t tot_len;
+	bool need_new_bio;
+	struct scatterlist *sg, *prev_sg = NULL;
+	struct bio *bio = NULL, *hbio = NULL, *tbio = NULL;
+	int bios;
+
+	if (unlikely((sgl == NULL) || (sgl->length == 0) || (nents <= 0))) {
+		WARN_ON(1);
+		res = -EINVAL;
+		goto out;
+	}
+
+	/*
+	 * Let's keep each bio allocation inside a single page to decrease
+	 * probability of failure.
+	 */
+	max_nr_vecs =  min_t(size_t,
+		((PAGE_SIZE - sizeof(struct bio)) / sizeof(struct bio_vec)),
+		BIO_MAX_PAGES);
+
+	need_new_bio = true;
+	tot_len = 0;
+	bios = 0;
+	for_each_sg(sgl, sg, nents, i) {
+		struct page *page = sg_page(sg);
+		void *page_addr = page_address(page);
+		size_t len = sg->length, l;
+		size_t offset = sg->offset;
+
+		tot_len += len;
+		prev_sg = sg;
+
+		/*
+		 * Each segment must be aligned on DMA boundary and
+		 * not on stack. The last one may have unaligned
+		 * length as long as the total length is aligned to
+		 * DMA padding alignment.
+		 */
+		if (i == nents - 1)
+			l = 0;
+		else
+			l = len;
+		if (((sg->offset | l) & queue_dma_alignment(q)) ||
+		    (page_addr && object_is_on_stack(page_addr + sg->offset))) {
+			res = -EINVAL;
+			goto out_free_bios;
+		}
+
+		while (len > 0) {
+			size_t bytes;
+			int rc;
+
+			if (need_new_bio) {
+				bio = bio_kmalloc(gfp, max_nr_vecs);
+				if (bio == NULL) {
+					res = -ENOMEM;
+					goto out_free_bios;
+				}
+
+				if (rw == WRITE)
+					bio->bi_rw |= REQ_WRITE;
+
+				bios++;
+				bio->bi_private = bw;
+				bio->bi_end_io = blk_bio_map_kern_endio;
+
+				if (hbio == NULL)
+					hbio = tbio = bio;
+				else
+					tbio = tbio->bi_next = bio;
+			}
+
+			bytes = min_t(size_t, len, PAGE_SIZE - offset);
+
+			rc = bio_add_pc_page(q, bio, page, bytes, offset);
+			if (rc < bytes) {
+				if (unlikely(need_new_bio || (rc < 0))) {
+					if (rc < 0)
+						res = rc;
+					else
+						res = -EIO;
+					goto out_free_bios;
+				} else {
+					need_new_bio = true;
+					len -= rc;
+					offset += rc;
+					continue;
+				}
+			}
+
+			need_new_bio = false;
+			offset = 0;
+			len -= bytes;
+			page = nth_page(page, 1);
+		}
+	}
+
+	if (hbio == NULL) {
+		res = -EINVAL;
+		goto out_free_bios;
+	}
+
+	/* Total length must be aligned on DMA padding alignment */
+	if ((tot_len & q->dma_pad_mask) &&
+	    !(rq->cmd_flags & REQ_COPY_USER)) {
+		res = -EINVAL;
+		goto out_free_bios;
+	}
+
+	if (bw != NULL)
+		atomic_set(&bw->bios_inflight, bios);
+
+	while (hbio != NULL) {
+		bio = hbio;
+		hbio = hbio->bi_next;
+		bio->bi_next = NULL;
+
+		blk_queue_bounce(q, &bio);
+
+		res = blk_rq_append_bio(q, rq, bio);
+		if (unlikely(res != 0)) {
+			bio->bi_next = hbio;
+			hbio = bio;
+			/* We can have one or more bios bounced */
+			goto out_unmap_bios;
+		}
+	}
+
+	res = 0;
+
+	rq->buffer = NULL;
+out:
+	return res;
+
+out_unmap_bios:
+	blk_rq_unmap_kern_sg(rq, res);
+
+out_free_bios:
+	while (hbio != NULL) {
+		bio = hbio;
+		hbio = hbio->bi_next;
+		bio_put(bio);
+	}
+	goto out;
+}
+
+/**
+ * blk_rq_map_kern_sg - map kernel data to a request, for REQ_TYPE_BLOCK_PC
+ * @rq:		request to fill
+ * @sgl:	area to map
+ * @nents:	number of elements in @sgl
+ * @gfp:	memory allocation flags
+ *
+ * Description:
+ *    Data will be mapped directly if possible. Otherwise a bounce
+ *    buffer will be used.
+ */
+int blk_rq_map_kern_sg(struct request *rq, struct scatterlist *sgl,
+		       int nents, gfp_t gfp)
+{
+	int res;
+
+	res = __blk_rq_map_kern_sg(rq, sgl, nents, NULL, gfp);
+	if (unlikely(res != 0)) {
+		struct blk_kern_sg_work *bw = NULL;
+
+		res = blk_rq_copy_kern_sg(rq, sgl, nents, &bw,
+				gfp, rq->q->bounce_gfp | gfp);
+		if (unlikely(res != 0))
+			goto out;
+
+		res = __blk_rq_map_kern_sg(rq, bw->sg_table.sgl,
+				bw->sg_table.nents, bw, gfp);
+		if (res != 0) {
+			blk_free_kern_sg_work(bw);
+			goto out;
+		}
+	}
+
+	rq->buffer = NULL;
+
+out:
+	return res;
+}
+EXPORT_SYMBOL(blk_rq_map_kern_sg);
+
+/**
+ * blk_rq_unmap_kern_sg - unmap a request with kernel sg
+ * @rq:		request to unmap
+ * @err:	non-zero error code
+ *
+ * Description:
+ *    Unmap a rq previously mapped by blk_rq_map_kern_sg(). Must be called
+ *    only in case of an error!
+ */
+void blk_rq_unmap_kern_sg(struct request *rq, int err)
+{
+	struct bio *bio = rq->bio;
+
+	while (bio) {
+		struct bio *b = bio;
+		bio = bio->bi_next;
+		b->bi_end_io(b, err);
+	}
+	rq->bio = NULL;
+
+	return;
+}
+EXPORT_SYMBOL(blk_rq_unmap_kern_sg);
+
+ /**
+  * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage
+  * @q:		request queue where request should be inserted
+diff -upkr linux-2.6.39/include/linux/blkdev.h linux-2.6.39/include/linux/blkdev.h
+--- linux-2.6.39/include/linux/blkdev.h	2011-05-19 00:06:34.000000000 -0400
+++ linux-2.6.39/include/linux/blkdev.h	2011-05-19 10:49:02.753812997 -0400
+@@ -592,6 +592,8 @@ extern unsigned long blk_max_low_pfn, bl
+ #define BLK_DEFAULT_SG_TIMEOUT	(60 * HZ)
+ #define BLK_MIN_SG_TIMEOUT	(7 * HZ)
+ 
+#define SCSI_EXEC_REQ_FIFO_DEFINED
+
+ #ifdef CONFIG_BOUNCE
+ extern int init_emergency_isa_pool(void);
+ extern void blk_queue_bounce(struct request_queue *q, struct bio **bio);
+@@ -707,6 +709,9 @@ extern int blk_rq_map_kern(struct reques
+ extern int blk_rq_map_user_iov(struct request_queue *, struct request *,
+ 			       struct rq_map_data *, struct sg_iovec *, int,
+ 			       unsigned int, gfp_t);
+extern int blk_rq_map_kern_sg(struct request *rq, struct scatterlist *sgl,
+			      int nents, gfp_t gfp);
+extern void blk_rq_unmap_kern_sg(struct request *rq, int err);
+ extern int blk_execute_rq(struct request_queue *, struct gendisk *,
+ 			  struct request *, int);
+ extern void blk_execute_rq_nowait(struct request_queue *, struct gendisk *,
+diff -upkr linux-2.6.39/include/linux/scatterlist.h linux-2.6.39/include/linux/scatterlist.h
+--- linux-2.6.39/include/linux/scatterlist.h	2011-05-19 00:06:34.000000000 -0400
+++ linux-2.6.39/include/linux/scatterlist.h	2011-05-19 10:49:02.753812997 -0400
+@@ -3,6 +3,7 @@
+ 
+ #include <asm/types.h>
+ #include <asm/scatterlist.h>
+#include <asm/kmap_types.h>
+ #include <linux/mm.h>
+ #include <linux/string.h>
+ #include <asm/io.h>
+@@ -218,6 +219,10 @@ size_t sg_copy_from_buffer(struct scatte
+ size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
+ 			 void *buf, size_t buflen);
+ 
+int sg_copy(struct scatterlist *dst_sg, struct scatterlist *src_sg,
+	    int nents_to_copy, size_t copy_len,
+	    enum km_type d_km_type, enum km_type s_km_type);
+
+ /*
+  * Maximum number of entries that will be allocated in one piece, if
+  * a list larger than this is required then chaining will be utilized.
+diff -upkr linux-2.6.39/lib/scatterlist.c linux-2.6.39/lib/scatterlist.c
+--- linux-2.6.39/lib/scatterlist.c	2011-05-19 00:06:34.000000000 -0400
+++ linux-2.6.39/lib/scatterlist.c	2011-05-19 10:49:02.753812997 -0400
+@@ -517,3 +517,132 @@ size_t sg_copy_to_buffer(struct scatterl
+ 	return sg_copy_buffer(sgl, nents, buf, buflen, 1);
+ }
+ EXPORT_SYMBOL(sg_copy_to_buffer);
+
+/*
+ * Can switch to the next dst_sg element, so, to copy to strictly only
+ * one dst_sg element, it must be either last in the chain, or
+ * copy_len == dst_sg->length.
+ */
+static int sg_copy_elem(struct scatterlist **pdst_sg, size_t *pdst_len,
+			size_t *pdst_offs, struct scatterlist *src_sg,
+			size_t copy_len,
+			enum km_type d_km_type, enum km_type s_km_type)
+{
+	int res = 0;
+	struct scatterlist *dst_sg;
+	size_t src_len, dst_len, src_offs, dst_offs;
+	struct page *src_page, *dst_page;
+
+	dst_sg = *pdst_sg;
+	dst_len = *pdst_len;
+	dst_offs = *pdst_offs;
+	dst_page = sg_page(dst_sg);
+
+	src_page = sg_page(src_sg);
+	src_len = src_sg->length;
+	src_offs = src_sg->offset;
+
+	do {
+		void *saddr, *daddr;
+		size_t n;
+
+		saddr = kmap_atomic(src_page +
+					 (src_offs >> PAGE_SHIFT), s_km_type) +
+				    (src_offs & ~PAGE_MASK);
+		daddr = kmap_atomic(dst_page +
+					(dst_offs >> PAGE_SHIFT), d_km_type) +
+				    (dst_offs & ~PAGE_MASK);
+
+		if (((src_offs & ~PAGE_MASK) == 0) &&
+		    ((dst_offs & ~PAGE_MASK) == 0) &&
+		    (src_len >= PAGE_SIZE) && (dst_len >= PAGE_SIZE) &&
+		    (copy_len >= PAGE_SIZE)) {
+			copy_page(daddr, saddr);
+			n = PAGE_SIZE;
+		} else {
+			n = min_t(size_t, PAGE_SIZE - (dst_offs & ~PAGE_MASK),
+					  PAGE_SIZE - (src_offs & ~PAGE_MASK));
+			n = min(n, src_len);
+			n = min(n, dst_len);
+			n = min_t(size_t, n, copy_len);
+			memcpy(daddr, saddr, n);
+		}
+		dst_offs += n;
+		src_offs += n;
+
+		kunmap_atomic(saddr, s_km_type);
+		kunmap_atomic(daddr, d_km_type);
+
+		res += n;
+		copy_len -= n;
+		if (copy_len == 0)
+			goto out;
+
+		src_len -= n;
+		dst_len -= n;
+		if (dst_len == 0) {
+			dst_sg = sg_next(dst_sg);
+			if (dst_sg == NULL)
+				goto out;
+			dst_page = sg_page(dst_sg);
+			dst_len = dst_sg->length;
+			dst_offs = dst_sg->offset;
+		}
+	} while (src_len > 0);
+
+out:
+	*pdst_sg = dst_sg;
+	*pdst_len = dst_len;
+	*pdst_offs = dst_offs;
+	return res;
+}
+
+/**
+ * sg_copy - copy one SG vector to another
+ * @dst_sg:	destination SG
+ * @src_sg:	source SG
+ * @nents_to_copy: maximum number of entries to copy
+ * @copy_len:	maximum amount of data to copy. If 0, then copy all.
+ * @d_km_type:	kmap_atomic type for the destination SG
+ * @s_km_type:	kmap_atomic type for the source SG
+ *
+ * Description:
+ *    Data from the source SG vector will be copied to the destination SG
+ *    vector. End of the vectors will be determined by sg_next() returning
+ *    NULL. Returns number of bytes copied.
+ */
+int sg_copy(struct scatterlist *dst_sg, struct scatterlist *src_sg,
+	    int nents_to_copy, size_t copy_len,
+	    enum km_type d_km_type, enum km_type s_km_type)
+{
+	int res = 0;
+	size_t dst_len, dst_offs;
+
+	if (copy_len == 0)
+		copy_len = 0x7FFFFFFF; /* copy all */
+
+	if (nents_to_copy == 0)
+		nents_to_copy = 0x7FFFFFFF; /* copy all */
+
+	dst_len = dst_sg->length;
+	dst_offs = dst_sg->offset;
+
+	do {
+		int copied = sg_copy_elem(&dst_sg, &dst_len, &dst_offs,
+				src_sg, copy_len, d_km_type, s_km_type);
+		copy_len -= copied;
+		res += copied;
+		if ((copy_len == 0) || (dst_sg == NULL))
+			goto out;
+
+		nents_to_copy--;
+		if (nents_to_copy == 0)
+			goto out;
+
+		src_sg = sg_next(src_sg);
+	} while (src_sg != NULL);
+
+out:
+	return res;
+}
+EXPORT_SYMBOL(sg_copy);
--- a/scst/src/dev_handlers/scst_vdisk.c
+++ b/scst/src/dev_handlers/scst_vdisk.c
@@ -2936,6 +2936,9 @@ static void blockio_exec_rw(struct scst_cmd *cmd, struct scst_vdisk_thr *thr,
 	struct scst_blockio_work *blockio_work;
 	int bios = 0;
 	gfp_t gfp_mask = (cmd->noio_mem_alloc ? GFP_NOIO : GFP_KERNEL);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 39)
+	struct blk_plug plug;
+#endif

 	TRACE_ENTRY();

@@ -3041,6 +3044,10 @@ static void blockio_exec_rw(struct scst_cmd *cmd, struct scst_vdisk_thr *thr,
 	/* +1 to prevent erroneous too early command completion */
 	atomic_set(&blockio_work->bios_inflight, bios+1);

+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 39)
+	blk_start_plug(&plug);
+#endif
+
 	while (hbio) {
 		bio = hbio;
 		hbio = hbio->bi_next;
@@ -3048,8 +3055,12 @@ static void blockio_exec_rw(struct scst_cmd *cmd, struct scst_vdisk_thr *thr,
 		submit_bio((write != 0), bio);
 	}

-	if (q && q->unplug_fn)
-		q->unplug_fn(q);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 39)
+	blk_finish_plug(&plug);
+#else
+ 	if (q && q->unplug_fn)
+ 		q->unplug_fn(q);
+#endif

 	blockio_check_finish(blockio_work);

--- a/scst/src/scst_pres.c
+++ b/scst/src/scst_pres.c
@@ -567,7 +567,8 @@ out:

 #ifndef CONFIG_SCST_PROC

-/* Abstract vfs_unlink & path_put for different kernel versions */
+/* Abstract vfs_unlink() for different kernel versions (as possible) */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 39)
 static inline void scst_pr_vfs_unlink_and_put(struct nameidata *nd)
 {
 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,25)
@@ -580,7 +581,15 @@ static inline void scst_pr_vfs_unlink_and_put(struct nameidata *nd)
 	path_put(&nd->path);
 #endif
 }
+#else
+static inline void scst_pr_vfs_unlink_and_put(struct path *path)
+{
+	vfs_unlink(path->dentry->d_parent->d_inode, path->dentry);
+	path_put(path);
+}
+#endif

+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 39)
 static inline void scst_pr_path_put(struct nameidata *nd)
 {
 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,25)
@@ -590,6 +599,7 @@ static inline void scst_pr_path_put(struct nameidata *nd)
 	path_put(&nd->path);
 #endif
 }
+#endif

 #if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 29)
 static int scst_pr_vfs_fsync(struct file *file, loff_t loff, loff_t len)
@@ -906,13 +916,18 @@ static void scst_pr_remove_device_files(struct scst_tgt_dev *tgt_dev)
 {
 	int res = 0;
 	struct scst_device *dev = tgt_dev->dev;
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 39)
 	struct nameidata nd;
+#else
+	struct path path;
+#endif
 	mm_segment_t old_fs = get_fs();

 	TRACE_ENTRY();

 	set_fs(KERNEL_DS);

+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 39)
 	res = path_lookup(dev->pr_file_name, 0, &nd);
 	if (!res)
 		scst_pr_vfs_unlink_and_put(&nd);
@@ -926,6 +941,21 @@ static void scst_pr_remove_device_files(struct scst_tgt_dev *tgt_dev)
 	else
 		TRACE_DBG("Unable to lookup file '%s' - error %d",
 			dev->pr_file_name1, res);
+#else
+	res = kern_path(dev->pr_file_name, 0, &path);
+	if (!res)
+		scst_pr_vfs_unlink_and_put(&path);
+	else
+		TRACE_DBG("Unable to lookup file '%s' - error %d",
+			dev->pr_file_name, res);
+
+	res = kern_path(dev->pr_file_name1, 0, &path);
+	if (!res)
+		scst_pr_vfs_unlink_and_put(&path);
+	else
+		TRACE_DBG("Unable to lookup file '%s' - error %d",
+			dev->pr_file_name1, res);
+#endif

 	set_fs(old_fs);

@@ -1104,6 +1134,7 @@ write_error:

 write_error_close:
 	filp_close(file, NULL);
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 39)
 	{
 		struct nameidata nd;
 		int rc;
@@ -1115,20 +1146,44 @@ write_error_close:
 			TRACE_PR("Unable to lookup '%s' - error %d",
 				dev->pr_file_name, rc);
 	}
+#else
+	{
+		struct path path;
+		int rc;
+
+		rc = kern_path(dev->pr_file_name, 0, &path);
+		if (!rc)
+			scst_pr_vfs_unlink_and_put(&path);
+		else
+			TRACE_PR("Unable to lookup '%s' - error %d",
+				dev->pr_file_name, rc);
+	}
+#endif
 	goto out_set_fs;
 }

 static int scst_pr_check_pr_path(void)
 {
 	int res;
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 39)
 	struct nameidata nd;
+#else
+	struct path path;
+#endif
+
 	mm_segment_t old_fs = get_fs();

 	TRACE_ENTRY();

 	set_fs(KERNEL_DS);

+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 39)
 	res = path_lookup(SCST_PR_DIR, 0, &nd);
+	scst_pr_path_put(&nd);
+#else
+	res = kern_path(SCST_PR_DIR, 0, &path);
+	path_put(&path);
+#endif
 	if (res != 0) {
 		PRINT_ERROR("Unable to find %s (err %d), you should create "
 			"this directory manually or reinstall SCST",
@@ -1136,8 +1191,6 @@ static int scst_pr_check_pr_path(void)
 		goto out_setfs;
 	}

-	scst_pr_path_put(&nd);
-
 out_setfs:
 	set_fs(old_fs);

--- a/scst/src/scst_targ.c
+++ b/scst/src/scst_targ.c
@@ -2635,9 +2635,11 @@ static inline int scst_real_exec(struct scst_cmd *cmd)
 	res = scst_do_real_exec(cmd);
 	if (likely(res == SCST_EXEC_COMPLETED)) {
 		scst_post_exec_sn(cmd, true);
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 39)
 		if (cmd->dev->scsi_dev != NULL)
 			generic_unplug_device(
 				cmd->dev->scsi_dev->request_queue);
+#endif
 	} else
 		sBUG();

@@ -2740,7 +2742,6 @@ static int scst_exec(struct scst_cmd **active_cmd)
 {
 	struct scst_cmd *cmd = *active_cmd;
 	struct scst_cmd *ref_cmd;
-	struct scst_device *dev = cmd->dev;
 	int res = SCST_CMD_STATE_RES_CONT_NEXT, count = 0;

 	TRACE_ENTRY();
@@ -2805,8 +2806,10 @@ done:
 	if (count == 0)
 		goto out_put;

-	if (dev->scsi_dev != NULL)
-		generic_unplug_device(dev->scsi_dev->request_queue);
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 39)
+	if (ref_cmd->dev->scsi_dev != NULL)
+		generic_unplug_device(ref_cmd->dev->scsi_dev->request_queue);
+#endif

 out_put:
 	__scst_cmd_put(ref_cmd);
--- a/scst_local/scst_local.c
+++ b/scst_local/scst_local.c
@@ -917,10 +917,16 @@ static int scst_local_send_resp(struct scsi_cmnd *cmnd,
 * This does the heavy lifting ... we pass all the commands on to the
 * target driver and have it do its magic ...
 */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 37) && \
+    defined(CONFIG_SCST_LOCAL_FORCE_DIRECT_PROCESSING)
+static int scst_local_queuecommand(struct Scsi_Host *host,
+	struct scsi_cmnd *SCpnt)
+#else
 static int scst_local_queuecommand_lck(struct scsi_cmnd *SCpnt,
 				       void (*done)(struct scsi_cmnd *))
 	__acquires(&h->host_lock)
 	__releases(&h->host_lock)
+#endif
 {
 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 25))
 	struct scst_local_tgt_specific *tgt_specific = NULL;
@@ -1071,23 +1077,32 @@ static int scst_local_queuecommand_lck(struct scsi_cmnd *SCpnt,

 /*
 * Although starting from 2.6.37 queuecommand() called with no host_lock
- * held, in reality without DEF_SCSI_QCMD() this doesn't work and leading
- * to various problems like commands lost under highload. So, until that fixed
- * we have to go ahead under host_lock, although absolutely don't need it.
- *
- * NOTE! At the moment in scst_estimate_context*() returning DIRECT contexts
- * disabled, so this option doesn't have any real effect.
+ * held, in fact without DEF_SCSI_QCMD() it doesn't work and leading
+ * to various problems like hangs under highload. Most likely, it is caused
+ * by some not reenrable block layer function(s). So, until that changed, we
+ * have to go ahead with extra context switch. In this regard doesn't matter
+ * much if we under host_lock or not (although we absolutely don't need this
+ * lock), so let's have simpler code with DEF_SCSI_QCMD().
 */
 #ifdef CONFIG_SCST_LOCAL_FORCE_DIRECT_PROCESSING
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 37)
+	scst_cmd_init_done(scst_cmd, SCST_CONTEXT_DIRECT);
+#else
 	{
+		/*
+		 * NOTE! At the moment in scst_estimate_context*() returning
+		 * DIRECT contexts disabled, so this option doesn't have any
+		 * real effect.
+		 */
 		struct Scsi_Host *h = SCpnt->device->host;
 		spin_unlock_irq(h->host_lock);
 		scst_cmd_init_done(scst_cmd, scst_estimate_context_atomic());
 		spin_lock_irq(h->host_lock);
 	}
+#endif
 #else
 	/*
-	 * Unfortunately, we called with IRQs disabled, so have no choice,
+	 * We called with IRQs disabled, so have no choice,
 	 * except to pass to the thread context.
 	 */
 	scst_cmd_init_done(scst_cmd, SCST_CONTEXT_THREAD);
@@ -1097,7 +1112,8 @@ static int scst_local_queuecommand_lck(struct scsi_cmnd *SCpnt,
 	return 0;
 }

-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 37)
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 37) && \
+    !defined(CONFIG_SCST_LOCAL_FORCE_DIRECT_PROCESSING)
 /*
 * See comment in scst_local_queuecommand_lck() near
 * CONFIG_SCST_LOCAL_FORCE_DIRECT_PROCESSING
@@ -1940,4 +1956,3 @@ static void __exit scst_local_exit(void)

 device_initcall(scst_local_init);
 module_exit(scst_local_exit);
-