lib/commands/toolcontext.c   |  2 ++

 lib/config/config_settings.h |  3 +++

 lib/config/defaults.h        |  1 +

 lib/device/bcache.c          | 42 ++++++++++++++++++++++++++++++++++++++++++

 lib/label/label.c            | 17 +++++++++++++----

 lib/misc/lvm-globals.c       | 11 +++++++++++

 lib/misc/lvm-globals.h       |  2 ++

 7 files changed, 74 insertions(+), 4 deletions(-)

diff --git a/lib/commands/toolcontext.c b/lib/commands/toolcontext.c

index 2b72645..4d3f744 100644

--- a/lib/commands/toolcontext.c

+++ b/lib/commands/toolcontext.c

@@ -341,6 +341,8 @@ static void _init_logging(struct cmd_context *cmd)

 	    find_config_tree_bool(cmd, global_test_CFG, NULL);

 	init_test(cmd->default_settings.test);

+	init_use_aio(find_config_tree_bool(cmd, global_use_aio_CFG, NULL));

+

 	/* Settings for logging to file */

 	if (find_config_tree_bool(cmd, log_overwrite_CFG, NULL))

 		append = 0;

diff --git a/lib/config/config_settings.h b/lib/config/config_settings.h

index 6d79087..2de3fd4 100644

--- a/lib/config/config_settings.h

+++ b/lib/config/config_settings.h

@@ -947,6 +947,9 @@ cfg(global_lvdisplay_shows_full_device_path_CFG, "lvdisplay_shows_full_device_pa

 	"Previously this was always shown as /dev/vgname/lvname even when that\n"

 	"was never a valid path in the /dev filesystem.\n")

+cfg(global_use_aio_CFG, "use_aio", global_CFG_SECTION, CFG_DEFAULT_COMMENTED, CFG_TYPE_BOOL, DEFAULT_USE_AIO, vsn(2, 2, 183), NULL, 0, NULL,

+	"Use async I/O when reading and writing devices.\n")

+

 cfg(global_use_lvmetad_CFG, "use_lvmetad", global_CFG_SECTION, 0, CFG_TYPE_BOOL, DEFAULT_USE_LVMETAD, vsn(2, 2, 93), "@DEFAULT_USE_LVMETAD@", 0, NULL,

 	"Use lvmetad to cache metadata and reduce disk scanning.\n"

 	"When enabled (and running), lvmetad provides LVM commands with VG\n"

diff --git a/lib/config/defaults.h b/lib/config/defaults.h

index 1a11009..b3e6c34 100644

--- a/lib/config/defaults.h

+++ b/lib/config/defaults.h

@@ -59,6 +59,7 @@

 #define DEFAULT_METADATA_READ_ONLY 0

 #define DEFAULT_LVDISPLAY_SHOWS_FULL_DEVICE_PATH 0

 #define DEFAULT_UNKNOWN_DEVICE_NAME "[unknown]"

+#define DEFAULT_USE_AIO 1

 #define DEFAULT_SANLOCK_LV_EXTEND_MB 256

diff --git a/lib/device/bcache.c b/lib/device/bcache.c

index 5ac2558..1cb1b2f 100644

--- a/lib/device/bcache.c

+++ b/lib/device/bcache.c

@@ -380,6 +380,48 @@ static bool _sync_issue(struct io_engine *ioe, enum dir d, int fd,

         	return false;

 	}

+	/*

+	 * If bcache block goes past where lvm wants to write, then clamp it.

+	 */

+	if ((d == DIR_WRITE) && _last_byte_offset && (fd == _last_byte_fd)) {

+		uint64_t offset = where;

+		uint64_t nbytes = len;

+		sector_t limit_nbytes = 0;

+		sector_t extra_nbytes = 0;

+

+		if (offset > _last_byte_offset) {

+			log_error("Limit write at %llu len %llu beyond last byte %llu",

+				  (unsigned long long)offset,

+				  (unsigned long long)nbytes,

+				  (unsigned long long)_last_byte_offset);

+			return false;

+		}

+

+		if (offset + nbytes > _last_byte_offset) {

+			limit_nbytes = _last_byte_offset - offset;

+			if (limit_nbytes % _last_byte_sector_size)

+				extra_nbytes = _last_byte_sector_size - (limit_nbytes % _last_byte_sector_size);

+

+			if (extra_nbytes) {

+				log_debug("Limit write at %llu len %llu to len %llu rounded to %llu",

+					  (unsigned long long)offset,

+					  (unsigned long long)nbytes,

+					  (unsigned long long)limit_nbytes,

+					  (unsigned long long)(limit_nbytes + extra_nbytes));

+				nbytes = limit_nbytes + extra_nbytes;

+			} else {

+				log_debug("Limit write at %llu len %llu to len %llu",

+					  (unsigned long long)offset,

+					  (unsigned long long)nbytes,

+					  (unsigned long long)limit_nbytes);

+				nbytes = limit_nbytes;

+			}

+		}

+

+		where = offset;

+		len = nbytes;

+	}

+

 	while (len) {

         	do {

                 	if (d == DIR_READ)

diff --git a/lib/label/label.c b/lib/label/label.c

index d2cfe62..e7e3997 100644

--- a/lib/label/label.c

+++ b/lib/label/label.c

@@ -797,7 +797,7 @@ out:

 static int _setup_bcache(int cache_blocks)

 {

-	struct io_engine *ioe;

+	struct io_engine *ioe = NULL;

 	if (cache_blocks < MIN_BCACHE_BLOCKS)

 		cache_blocks = MIN_BCACHE_BLOCKS;

@@ -805,9 +805,18 @@ static int _setup_bcache(int cache_blocks)

 	if (cache_blocks > MAX_BCACHE_BLOCKS)

 		cache_blocks = MAX_BCACHE_BLOCKS;

-	if (!(ioe = create_async_io_engine())) {

-		log_error("Failed to create bcache io engine.");

-		return 0;

+	if (use_aio()) {

+		if (!(ioe = create_async_io_engine())) {

+			log_warn("Failed to set up async io, using sync io.");

+			init_use_aio(0);

+		}

+	}

+

+	if (!ioe) {

+		if (!(ioe = create_sync_io_engine())) {

+			log_error("Failed to set up sync io.");

+			return 0;

+		}

 	}

 	if (!(scan_bcache = bcache_create(BCACHE_BLOCK_SIZE_IN_SECTORS, cache_blocks, ioe))) {

diff --git a/lib/misc/lvm-globals.c b/lib/misc/lvm-globals.c

index 9941489..82c5706 100644

--- a/lib/misc/lvm-globals.c

+++ b/lib/misc/lvm-globals.c

@@ -24,6 +24,7 @@

 static int _verbose_level = VERBOSE_BASE_LEVEL;

 static int _silent = 0;

 static int _test = 0;

+static int _use_aio = 0;

 static int _md_filtering = 0;

 static int _internal_filtering = 0;

 static int _fwraid_filtering = 0;

@@ -71,6 +72,11 @@ void init_test(int level)

 	_test = level;

 }

+void init_use_aio(int use_aio)

+{

+	_use_aio = use_aio;

+}

+

 void init_md_filtering(int level)

 {

 	_md_filtering = level;

@@ -227,6 +233,11 @@ int test_mode(void)

 	return _test;

 }

+int use_aio(void)

+{

+	return _use_aio;

+}

+

 int md_filtering(void)

 {

 	return _md_filtering;

diff --git a/lib/misc/lvm-globals.h b/lib/misc/lvm-globals.h

index b383891..f985cfa 100644

--- a/lib/misc/lvm-globals.h

+++ b/lib/misc/lvm-globals.h

@@ -25,6 +25,7 @@ enum dev_ext_e;

 void init_verbose(int level);

 void init_silent(int silent);

 void init_test(int level);

+void init_use_aio(int use_aio);

 void init_md_filtering(int level);

 void init_internal_filtering(int level);

 void init_fwraid_filtering(int level);

@@ -58,6 +59,7 @@ const char *get_cmd_name(void);

 void set_sysfs_dir_path(const char *path);

 int test_mode(void);

+int use_aio(void);

 int md_filtering(void);

 int internal_filtering(void);

 int fwraid_filtering(void);