From: Kris Davis <Kris.Davis@hgst.com>
Date: Wed, 30 Sep 2015 15:57:16 +0000 (+0200)
Subject: sg: 16-byte cdb support and lots of fixes
X-Git-Tag: fio-2.2.11~29
X-Git-Url: https://git.kernel.dk/?p=fio.git;a=commitdiff_plain;h=5ad7be56;hp=194fffd042d374d5e13af61a14fe16734c396d8c

sg: 16-byte cdb support and lots of fixes

-- Fixed prob with queue depths > 1 (usually would work at qd = 2,
   but had fundimental prob with retrieving multiple events)
   Only works up to QD 16 due to kernel limitation.

-- Fix problem with check and report scsi operation errors.
   There was no check, so op errors were being ignored.
   Added support to retrieve and print sense data to output.

-- Fix problem with op timeouts. No timeouts op time out was being set.
   Hardcoded to 30 seconds.

-- Support switch to 16 Byte operations when LBA range needed.

-- Set default size based on maxlba of device retrieved
   from ReadCapacity command.

Updated by Jens to:

- ->errdetails() must be reentrant. Return an allocated buffer, have
  the caller free it when done.

- Bump io engine version number, the ops have changed.

- Add strlcat() as a real helper, don't stuff it in sg.c

- Lots of style cleanups

Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/Makefile b/Makefile
index 296655bc..d287126e 100644
--- a/Makefile
+++ b/Makefile
@@ -104,6 +104,9 @@ endif
 ifndef CONFIG_STRCASESTR
   SOURCE += lib/strcasestr.c
 endif
+ifndef CONFIG_STRLCAT
+  SOURCE += lib/strlcat.c
+endif
 ifndef CONFIG_GETOPT_LONG_ONLY
   SOURCE += lib/getopt_long.c
 endif
diff --git a/configure b/configure
index ee096b3a..74897752 100755
--- a/configure
+++ b/configure
@@ -964,6 +964,25 @@ if compile_prog "" "" "strcasestr"; then
 fi
 echo "strcasestr                    $strcasestr"
 
+##########################################
+# strlcat() probe
+strlcat="no"
+cat > $TMPC << EOF
+#include <string.h>
+int main(int argc, char **argv)
+{
+  static char dst[64];
+  static char *string = "This is a string";
+  memset(dst, 0, sizeof(dst));
+  strlcat(dst, string, sizeof(dst));
+  return 0;
+}
+EOF
+if compile_prog "" "" "strlcat"; then
+  strlcat="yes"
+fi
+echo "strlcat                       $strlcat"
+
 ##########################################
 # getopt_long_only() probe
 getopt_long_only="no"
@@ -1612,6 +1631,9 @@ fi
 if test "$strcasestr" = "yes" ; then
   output_sym "CONFIG_STRCASESTR"
 fi
+if test "$strlcat" = "yes" ; then
+  output_sym "CONFIG_STRLCAT"
+fi
 if test "$getopt_long_only" = "yes" ; then
   output_sym "CONFIG_GETOPT_LONG_ONLY"
 fi
diff --git a/engines/sg.c b/engines/sg.c
index 8acbd50a..c24b323f 100644
--- a/engines/sg.c
+++ b/engines/sg.c
@@ -15,8 +15,13 @@
 
 #ifdef FIO_HAVE_SGIO
 
+#define MAX_10B_LBA  0xFFFFFFFFULL
+#define SCSI_TIMEOUT_MS 30000   // 30 second timeout; currently no method to override
+#define MAX_SB 64               // sense block maximum return size
+
 struct sgio_cmd {
-	unsigned char cdb[10];
+	unsigned char cdb[16];  	// increase to support 16 byte commands
+	unsigned char sb[MAX_SB];   // add sense block to commands
 	int nr;
 };
 
@@ -27,6 +32,7 @@ struct sgio_data {
 	int *fd_flags;
 	void *sgbuf;
 	unsigned int bs;
+	long long max_lba;
 	int type_checked;
 };
 
@@ -41,6 +47,8 @@ static void sgio_hdr_init(struct sgio_data *sd, struct sg_io_hdr *hdr,
 	hdr->interface_id = 'S';
 	hdr->cmdp = sc->cdb;
 	hdr->cmd_len = sizeof(sc->cdb);
+	hdr->sbp = sc->sb;
+	hdr->mx_sb_len = sizeof(sc->sb);
 	hdr->pack_id = io_u->index;
 	hdr->usr_ptr = io_u;
 
@@ -66,7 +74,7 @@ static int fio_sgio_getevents(struct thread_data *td, unsigned int min,
 			      const struct timespec fio_unused *t)
 {
 	struct sgio_data *sd = td->io_ops->data;
-	int left = max, ret, r = 0;
+	int left = max, eventNum, ret, r = 0;
 	void *buf = sd->sgbuf;
 	unsigned int i, events;
 	struct fio_file *f;
@@ -90,6 +98,8 @@ static int fio_sgio_getevents(struct thread_data *td, unsigned int min,
 	while (left) {
 		void *p;
 
+		dprint(FD_IO, "sgio_getevents: sd %p: left=%d\n", sd, left);
+
 		do {
 			if (!min)
 				break;
@@ -114,16 +124,24 @@ re_read:
 		p = buf;
 		events = 0;
 		for_each_file(td, f, i) {
-			ret = read(f->fd, p, left * sizeof(struct sg_io_hdr));
-			if (ret < 0) {
-				if (errno == EAGAIN)
-					continue;
-				r = -errno;
-				td_verror(td, errno, "read");
-				break;
-			} else if (ret) {
-				p += ret;
-				events += ret / sizeof(struct sg_io_hdr);
+			for (eventNum = 0; eventNum < left; eventNum++) {
+				ret = read(f->fd, p, sizeof(struct sg_io_hdr));
+				dprint(FD_IO, "sgio_getevents: ret: %d\n", ret);
+				if (ret < 0) {
+					/*
+					 *  not sure if EINTR is needed,
+					 *  but seems like it should be.
+					 */
+					if (errno == EAGAIN || errno == EINTR)
+						continue;
+					r = -errno;
+					td_verror(td, errno, "read");
+					break;
+				} else if (ret) {
+					p += ret;
+					events += 1;  /* ret / sizeof(struct sg_io_hdr); */
+					dprint(FD_IO, "sgio_getevents: events: %d\n", events);
+				}
 			}
 		}
 
@@ -139,8 +157,15 @@ re_read:
 
 		for (i = 0; i < events; i++) {
 			struct sg_io_hdr *hdr = (struct sg_io_hdr *) buf + i;
-
 			sd->events[i] = hdr->usr_ptr;
+
+			/* record if an io error occurred, ignore resid */
+			if (hdr->info & SG_INFO_CHECK) {
+				struct io_u *io_u;
+				io_u = (struct io_u *)(hdr->usr_ptr);
+				memcpy((void*)&(io_u->hdr), (void*)hdr, sizeof(struct sg_io_hdr));
+				sd->events[i]->error = EIO;
+			}
 		}
 	}
 
@@ -170,6 +195,10 @@ static int fio_sgio_ioctl_doio(struct thread_data *td,
 	if (ret < 0)
 		return ret;
 
+	/* record if an io error occurred */
+	if (hdr->info & SG_INFO_CHECK)
+		io_u->error = EIO;
+
 	return FIO_Q_COMPLETED;
 }
 
@@ -186,6 +215,11 @@ static int fio_sgio_rw_doio(struct fio_file *f, struct io_u *io_u, int do_sync)
 		ret = read(f->fd, hdr, sizeof(*hdr));
 		if (ret < 0)
 			return ret;
+
+		/* record if an io error occurred */
+		if (hdr->info & SG_INFO_CHECK)
+			io_u->error = EIO;
+
 		return FIO_Q_COMPLETED;
 	}
 
@@ -195,52 +229,89 @@ static int fio_sgio_rw_doio(struct fio_file *f, struct io_u *io_u, int do_sync)
 static int fio_sgio_doio(struct thread_data *td, struct io_u *io_u, int do_sync)
 {
 	struct fio_file *f = io_u->file;
+	int ret;
 
-	if (f->filetype == FIO_TYPE_BD)
-		return fio_sgio_ioctl_doio(td, f, io_u);
+	if (f->filetype == FIO_TYPE_BD) {
+		ret = fio_sgio_ioctl_doio(td, f, io_u);
+		td->error = io_u->error;
+	} else {
+		ret = fio_sgio_rw_doio(f, io_u, do_sync);
+		if (do_sync)
+			td->error = io_u->error;
+	}
 
-	return fio_sgio_rw_doio(f, io_u, do_sync);
+	return ret;
 }
 
 static int fio_sgio_prep(struct thread_data *td, struct io_u *io_u)
 {
 	struct sg_io_hdr *hdr = &io_u->hdr;
 	struct sgio_data *sd = td->io_ops->data;
-	int nr_blocks, lba;
+	long long nr_blocks, lba;
 
 	if (io_u->xfer_buflen & (sd->bs - 1)) {
 		log_err("read/write not sector aligned\n");
 		return EINVAL;
 	}
 
+	nr_blocks = io_u->xfer_buflen / sd->bs;
+	lba = io_u->offset / sd->bs;
+
 	if (io_u->ddir == DDIR_READ) {
 		sgio_hdr_init(sd, hdr, io_u, 1);
 
 		hdr->dxfer_direction = SG_DXFER_FROM_DEV;
-		hdr->cmdp[0] = 0x28;
+		if (lba < MAX_10B_LBA)
+			hdr->cmdp[0] = 0x28; // read(10)
+		else
+			hdr->cmdp[0] = 0x88; // read(16)
 	} else if (io_u->ddir == DDIR_WRITE) {
 		sgio_hdr_init(sd, hdr, io_u, 1);
 
 		hdr->dxfer_direction = SG_DXFER_TO_DEV;
-		hdr->cmdp[0] = 0x2a;
+		if (lba < MAX_10B_LBA)
+			hdr->cmdp[0] = 0x2a; // write(10)
+		else
+			hdr->cmdp[0] = 0x8a; // write(16)
 	} else {
 		sgio_hdr_init(sd, hdr, io_u, 0);
-
 		hdr->dxfer_direction = SG_DXFER_NONE;
-		hdr->cmdp[0] = 0x35;
+		if (lba < MAX_10B_LBA)
+			hdr->cmdp[0] = 0x35; // synccache(10)
+		else
+			hdr->cmdp[0] = 0x91; // synccache(16)
 	}
 
+	/*
+	 * for synccache, we leave lba and length to 0 to sync all
+	 * blocks on medium.
+	 */
 	if (hdr->dxfer_direction != SG_DXFER_NONE) {
-		nr_blocks = io_u->xfer_buflen / sd->bs;
-		lba = io_u->offset / sd->bs;
-		hdr->cmdp[2] = (unsigned char) ((lba >> 24) & 0xff);
-		hdr->cmdp[3] = (unsigned char) ((lba >> 16) & 0xff);
-		hdr->cmdp[4] = (unsigned char) ((lba >>  8) & 0xff);
-		hdr->cmdp[5] = (unsigned char) (lba & 0xff);
-		hdr->cmdp[7] = (unsigned char) ((nr_blocks >> 8) & 0xff);
-		hdr->cmdp[8] = (unsigned char) (nr_blocks & 0xff);
+
+		if (lba < MAX_10B_LBA) {
+			hdr->cmdp[2] = (unsigned char) ((lba >> 24) & 0xff);
+			hdr->cmdp[3] = (unsigned char) ((lba >> 16) & 0xff);
+			hdr->cmdp[4] = (unsigned char) ((lba >>  8) & 0xff);
+			hdr->cmdp[5] = (unsigned char) (lba & 0xff);
+			hdr->cmdp[7] = (unsigned char) ((nr_blocks >> 8) & 0xff);
+			hdr->cmdp[8] = (unsigned char) (nr_blocks & 0xff);
+		} else {
+			hdr->cmdp[2] = (unsigned char) ((lba >> 56) & 0xff);
+			hdr->cmdp[3] = (unsigned char) ((lba >> 48) & 0xff);
+			hdr->cmdp[4] = (unsigned char) ((lba >> 40) & 0xff);
+			hdr->cmdp[5] = (unsigned char) ((lba >> 32) & 0xff);
+			hdr->cmdp[6] = (unsigned char) ((lba >> 24) & 0xff);
+			hdr->cmdp[7] = (unsigned char) ((lba >> 16) & 0xff);
+			hdr->cmdp[8] = (unsigned char) ((lba >>  8) & 0xff);
+			hdr->cmdp[9] = (unsigned char) (lba & 0xff);
+			hdr->cmdp[10] = (unsigned char) ((nr_blocks >> 32) & 0xff);
+			hdr->cmdp[11] = (unsigned char) ((nr_blocks >> 16) & 0xff);
+			hdr->cmdp[12] = (unsigned char) ((nr_blocks >> 8) & 0xff);
+			hdr->cmdp[13] = (unsigned char) (nr_blocks & 0xff);
+		}
 	}
 
+	hdr->timeout = SCSI_TIMEOUT_MS;
 	return 0;
 }
 
@@ -278,31 +349,93 @@ static struct io_u *fio_sgio_event(struct thread_data *td, int event)
 	return sd->events[event];
 }
 
-static int fio_sgio_get_bs(struct thread_data *td, unsigned int *bs)
+static int fio_sgio_read_capacity(struct thread_data *td, unsigned int *bs,
+				  unsigned long long *max_lba)
 {
-	struct sgio_data *sd = td->io_ops->data;
-	struct io_u io_u;
-	struct sg_io_hdr *hdr;
-	unsigned char buf[8];
+	/*
+	 * need to do read capacity operation w/o benefit of sd or
+	 * io_u structures, which are not initialized until later.
+	 */
+	struct sg_io_hdr hdr;
+	unsigned char cmd[16];
+	unsigned char sb[64];
+	unsigned char buf[32];  // read capacity return
 	int ret;
+	int fd = -1;
 
-	memset(&io_u, 0, sizeof(io_u));
-	io_u.file = td->files[0];
+	struct fio_file *f = td->files[0];
 
-	hdr = &io_u.hdr;
-	sgio_hdr_init(sd, hdr, &io_u, 0);
-	memset(buf, 0, sizeof(buf));
+	/* open file independent of rest of application */
+	fd = open(f->file_name, O_RDONLY);
+	if (fd < 0)
+		return -errno;
 
-	hdr->cmdp[0] = 0x25;
-	hdr->dxfer_direction = SG_DXFER_FROM_DEV;
-	hdr->dxferp = buf;
-	hdr->dxfer_len = sizeof(buf);
+	memset(&hdr, 0, sizeof(hdr));
+	memset(cmd, 0, sizeof(cmd));
+	memset(sb, 0, sizeof(sb));
+	memset(buf, 0, sizeof(buf));
 
-	ret = fio_sgio_doio(td, &io_u, 1);
-	if (ret)
+	/* First let's try a 10 byte read capacity. */
+	hdr.interface_id = 'S';
+	hdr.cmdp = cmd;
+	hdr.cmd_len = 10;
+	hdr.sbp = sb;
+	hdr.mx_sb_len = sizeof(sb);
+	hdr.timeout = SCSI_TIMEOUT_MS;
+	hdr.cmdp[0] = 0x25;  // Read Capacity(10)
+	hdr.dxfer_direction = SG_DXFER_FROM_DEV;
+	hdr.dxferp = buf;
+	hdr.dxfer_len = sizeof(buf);
+
+	ret = ioctl(fd, SG_IO, &hdr);
+	if (ret < 0) {
+		close(fd);
 		return ret;
+	}
 
-	*bs = (buf[4] << 24) | (buf[5] << 16) | (buf[6] << 8) | buf[7];
+	*bs	 = (buf[4] << 24) | (buf[5] << 16) | (buf[6] << 8) | buf[7];
+	*max_lba = ((buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3]) & 0x00000000FFFFFFFFULL;  // for some reason max_lba is being sign extended even though unsigned.
+
+
+	/*
+	 * If max lba is 0xFFFFFFFF, then need to retry with
+	 * 16 byteread capacity
+	 */
+	if (*max_lba == MAX_10B_LBA) {
+		hdr.cmd_len = 16;
+		hdr.cmdp[0] = 0x9e; // Read Capacity(16)
+		hdr.cmdp[1] = 0x10; // service action
+		hdr.cmdp[10] = (unsigned char) ((sizeof(buf) >> 24) & 0xff);
+		hdr.cmdp[11] = (unsigned char) ((sizeof(buf) >> 16) & 0xff);
+		hdr.cmdp[12] = (unsigned char) ((sizeof(buf) >> 8) & 0xff);
+		hdr.cmdp[13] = (unsigned char) (sizeof(buf) & 0xff);
+
+		hdr.dxfer_direction = SG_DXFER_FROM_DEV;
+		hdr.dxferp = buf;
+		hdr.dxfer_len = sizeof(buf);
+
+		ret = ioctl(fd, SG_IO, &hdr);
+		if (ret < 0) {
+			close(fd);
+			return ret;
+		}
+
+		/* record if an io error occurred */
+		if (hdr.info & SG_INFO_CHECK)
+			td_verror(td, EIO, "fio_sgio_read_capacity");
+
+		*bs = (buf[8] << 24) | (buf[9] << 16) | (buf[10] << 8) | buf[11];
+		*max_lba = ((unsigned long long)buf[0] << 56) |
+				((unsigned long long)buf[1] << 48) |
+				((unsigned long long)buf[2] << 40) |
+				((unsigned long long)buf[3] << 32) |
+				((unsigned long long)buf[4] << 24) |
+				((unsigned long long)buf[5] << 16) |
+				((unsigned long long)buf[6] << 8) |
+				(unsigned long long)buf[7];
+	}
+
+	close(fd);
 	return 0;
 }
 
@@ -336,7 +469,7 @@ static int fio_sgio_init(struct thread_data *td)
 	memset(sd->fd_flags, 0, sizeof(int) * td->o.nr_files);
 	sd->sgbuf = malloc(sizeof(struct sg_io_hdr) * td->o.iodepth);
 	memset(sd->sgbuf, 0, sizeof(struct sg_io_hdr) * td->o.iodepth);
-
+	sd->type_checked = 0;
 	td->io_ops->data = sd;
 
 	/*
@@ -349,7 +482,9 @@ static int fio_sgio_init(struct thread_data *td)
 static int fio_sgio_type_check(struct thread_data *td, struct fio_file *f)
 {
 	struct sgio_data *sd = td->io_ops->data;
-	unsigned int bs;
+	unsigned int bs = 0;
+	unsigned long long max_lba = 0;
+
 
 	if (f->filetype == FIO_TYPE_BD) {
 		if (ioctl(f->fd, BLKSSZGET, &bs) < 0) {
@@ -364,9 +499,12 @@ static int fio_sgio_type_check(struct thread_data *td, struct fio_file *f)
 			return 1;
 		}
 
-		ret = fio_sgio_get_bs(td, &bs);
-		if (ret)
+		ret = fio_sgio_read_capacity(td, &bs, &max_lba);
+		if (ret) {
+			td_verror(td, td->error, "fio_sgio_read_capacity");
+			log_err("ioengine sg unable to read capacity successfully\n");
 			return 1;
+		}
 	} else {
 		td_verror(td, EINVAL, "wrong file type");
 		log_err("ioengine sg only works on block devices\n");
@@ -374,11 +512,18 @@ static int fio_sgio_type_check(struct thread_data *td, struct fio_file *f)
 	}
 
 	sd->bs = bs;
+	// Determine size of commands needed based on max_lba
+	sd->max_lba = max_lba;
+	if (max_lba > MAX_10B_LBA) {
+		dprint(FD_IO, "sgio_type_check: using 16 byte operations: max_lba = 0x%016llx\n", max_lba);
+	}
+
 
 	if (f->filetype == FIO_TYPE_BD) {
 		td->io_ops->getevents = NULL;
 		td->io_ops->event = NULL;
 	}
+	sd->type_checked = 1;
 
 	return 0;
 }
@@ -400,6 +545,227 @@ static int fio_sgio_open(struct thread_data *td, struct fio_file *f)
 	return 0;
 }
 
+/*
+ * Build an error string with details about the driver, host or scsi
+ * error contained in the sg header Caller will use as necessary.
+ */
+static char *fio_sgio_errdetails(struct io_u *io_u)
+{
+	struct sg_io_hdr *hdr = &io_u->hdr;
+#define MAXERRDETAIL 1024
+#define MAXMSGCHUNK  128
+	char *msg, msgchunk[MAXMSGCHUNK], *ret = NULL;
+	int i;
+
+	msg = calloc(MAXERRDETAIL, 1);
+
+	/*
+	 * can't seem to find sg_err.h, so I'll just echo the define values
+	 * so others can search on internet to find clearer clues of meaning.
+	 */
+	if (hdr->info & SG_INFO_CHECK) {
+		ret = msg;
+		if (hdr->host_status) {
+			snprintf(msgchunk, MAXMSGCHUNK, "SG Host Status: 0x%02x; ", hdr->host_status);
+			strlcat(msg, msgchunk, MAXERRDETAIL);
+			switch (hdr->host_status) {
+			case 0x01:
+				strlcat(msg, "SG_ERR_DID_NO_CONNECT", MAXERRDETAIL);
+				break;
+			case 0x02:
+				strlcat(msg, "SG_ERR_DID_BUS_BUSY", MAXERRDETAIL);
+				break;
+			case 0x03:
+				strlcat(msg, "SG_ERR_DID_TIME_OUT", MAXERRDETAIL);
+				break;
+			case 0x04:
+				strlcat(msg, "SG_ERR_DID_BAD_TARGET", MAXERRDETAIL);
+				break;
+			case 0x05:
+				strlcat(msg, "SG_ERR_DID_ABORT", MAXERRDETAIL);
+				break;
+			case 0x06:
+				strlcat(msg, "SG_ERR_DID_PARITY", MAXERRDETAIL);
+				break;
+			case 0x07:
+				strlcat(msg, "SG_ERR_DID_ERROR (internal error)", MAXERRDETAIL);
+				break;
+			case 0x08:
+				strlcat(msg, "SG_ERR_DID_RESET", MAXERRDETAIL);
+				break;
+			case 0x09:
+				strlcat(msg, "SG_ERR_DID_BAD_INTR (unexpected)", MAXERRDETAIL);
+				break;
+			case 0x0a:
+				strlcat(msg, "SG_ERR_DID_PASSTHROUGH", MAXERRDETAIL);
+				break;
+			case 0x0b:
+				strlcat(msg, "SG_ERR_DID_SOFT_ERROR (driver retry?)", MAXERRDETAIL);
+				break;
+			case 0x0c:
+				strlcat(msg, "SG_ERR_DID_IMM_RETRY", MAXERRDETAIL);
+				break;
+			case 0x0d:
+				strlcat(msg, "SG_ERR_DID_REQUEUE", MAXERRDETAIL);
+				break;
+			default:
+				strlcat(msg, "Unknown", MAXERRDETAIL);
+				break;
+			}
+			strlcat(msg, ". ", MAXERRDETAIL);
+		}
+		if (hdr->driver_status) {
+			snprintf(msgchunk, MAXMSGCHUNK, "SG Driver Status: 0x%02x; ", hdr->driver_status);
+			strlcat(msg, msgchunk, MAXERRDETAIL);
+			switch (hdr->driver_status & 0x0F) {
+			case 0x01:
+				strlcat(msg, "SG_ERR_DRIVER_BUSY", MAXERRDETAIL);
+				break;
+			case 0x02:
+				strlcat(msg, "SG_ERR_DRIVER_SOFT", MAXERRDETAIL);
+				break;
+			case 0x03:
+				strlcat(msg, "SG_ERR_DRIVER_MEDIA", MAXERRDETAIL);
+				break;
+			case 0x04:
+				strlcat(msg, "SG_ERR_DRIVER_ERROR", MAXERRDETAIL);
+				break;
+			case 0x05:
+				strlcat(msg, "SG_ERR_DRIVER_INVALID", MAXERRDETAIL);
+				break;
+			case 0x06:
+				strlcat(msg, "SG_ERR_DRIVER_TIMEOUT", MAXERRDETAIL);
+				break;
+			case 0x07:
+				strlcat(msg, "SG_ERR_DRIVER_HARD", MAXERRDETAIL);
+				break;
+			case 0x08:
+				strlcat(msg, "SG_ERR_DRIVER_SENSE", MAXERRDETAIL);
+				break;
+			default:
+				strlcat(msg, "Unknown", MAXERRDETAIL);
+				break;
+			}
+			strlcat(msg, "; ", MAXERRDETAIL);
+			switch (hdr->driver_status & 0xF0) {
+			case 0x10:
+				strlcat(msg, "SG_ERR_SUGGEST_RETRY", MAXERRDETAIL);
+				break;
+			case 0x20:
+				strlcat(msg, "SG_ERR_SUGGEST_ABORT", MAXERRDETAIL);
+				break;
+			case 0x30:
+				strlcat(msg, "SG_ERR_SUGGEST_REMAP", MAXERRDETAIL);
+				break;
+			case 0x40:
+				strlcat(msg, "SG_ERR_SUGGEST_DIE", MAXERRDETAIL);
+				break;
+			case 0x80:
+				strlcat(msg, "SG_ERR_SUGGEST_SENSE", MAXERRDETAIL);
+				break;
+			}
+			strlcat(msg, ". ", MAXERRDETAIL);
+		}
+		if (hdr->status) {
+			snprintf(msgchunk, MAXMSGCHUNK, "SG SCSI Status: 0x%02x; ", hdr->status);
+			strlcat(msg, msgchunk, MAXERRDETAIL);
+			// SCSI 3 status codes
+			switch (hdr->status) {
+			case 0x02:
+				strlcat(msg, "CHECK_CONDITION", MAXERRDETAIL);
+				break;
+			case 0x04:
+				strlcat(msg, "CONDITION_MET", MAXERRDETAIL);
+				break;
+			case 0x08:
+				strlcat(msg, "BUSY", MAXERRDETAIL);
+				break;
+			case 0x10:
+				strlcat(msg, "INTERMEDIATE", MAXERRDETAIL);
+				break;
+			case 0x14:
+				strlcat(msg, "INTERMEDIATE_CONDITION_MET", MAXERRDETAIL);
+				break;
+			case 0x18:
+				strlcat(msg, "RESERVATION_CONFLICT", MAXERRDETAIL);
+				break;
+			case 0x22:
+				strlcat(msg, "COMMAND_TERMINATED", MAXERRDETAIL);
+				break;
+			case 0x28:
+				strlcat(msg, "TASK_SET_FULL", MAXERRDETAIL);
+				break;
+			case 0x30:
+				strlcat(msg, "ACA_ACTIVE", MAXERRDETAIL);
+				break;
+			case 0x40:
+				strlcat(msg, "TASK_ABORTED", MAXERRDETAIL);
+				break;
+			default:
+				strlcat(msg, "Unknown", MAXERRDETAIL);
+				break;
+			}
+			strlcat(msg, ". ", MAXERRDETAIL);
+		}
+		if (hdr->sb_len_wr) {
+			snprintf(msgchunk, MAXMSGCHUNK, "Sense Data (%d bytes):", hdr->sb_len_wr);
+			strlcat(msg, msgchunk, MAXERRDETAIL);
+			for (i = 0; i < hdr->sb_len_wr; i++) {
+				snprintf(msgchunk, MAXMSGCHUNK, " %02x", hdr->sbp[i]);
+				strlcat(msg, msgchunk, MAXERRDETAIL);
+			}
+			strlcat(msg, ". ", MAXERRDETAIL);
+		}
+		if (hdr->resid != 0) {
+			snprintf(msgchunk, MAXMSGCHUNK, "SG Driver: %d bytes out of %d not transferred. ", hdr->resid, hdr->dxfer_len);
+			strlcat(msg, msgchunk, MAXERRDETAIL);
+			ret = msg;
+		}
+	}
+
+	if (!ret)
+		ret = strdup("SG Driver did not report a Host, Driver or Device check");
+
+	return ret;
+}
+
+/*
+ * get max file size from read capacity.
+ */
+static int fio_sgio_get_file_size(struct thread_data *td, struct fio_file *f)
+{
+	/*
+	 * get_file_size is being called even before sgio_init is
+	 * called, so none of the sg_io structures are
+	 * initialized in the thread_data yet.  So we need to do the
+	 * ReadCapacity without any of those helpers.  One of the effects
+	 * is that ReadCapacity may get called 4 times on each open:
+	 * readcap(10) followed by readcap(16) if needed - just to get
+	 * the file size after the init occurs - it will be called
+	 * again when "type_check" is called during structure
+	 * initialization I'm not sure how to prevent this little
+	 * inefficiency.
+	 */
+	unsigned int bs = 0;
+	unsigned long long max_lba = 0;
+	int ret;
+
+	if (fio_file_size_known(f))
+		return 0;
+
+	ret = fio_sgio_read_capacity(td, &bs, &max_lba);
+	if (ret ) {
+		td_verror(td, td->error, "fio_sgio_read_capacity");
+		log_err("ioengine sg unable to successfully execute read capacity to get block size and maximum lba\n");
+		return 1;
+	}
+
+	f->real_file_size = (max_lba + 1) * bs;
+	fio_file_set_size_known(f);
+	return 0;
+}
+
+
 static struct ioengine_ops ioengine = {
 	.name		= "sg",
 	.version	= FIO_IOOPS_VERSION,
@@ -407,11 +773,12 @@ static struct ioengine_ops ioengine = {
 	.prep		= fio_sgio_prep,
 	.queue		= fio_sgio_queue,
 	.getevents	= fio_sgio_getevents,
+	.errdetails	= fio_sgio_errdetails,
 	.event		= fio_sgio_event,
 	.cleanup	= fio_sgio_cleanup,
 	.open_file	= fio_sgio_open,
 	.close_file	= generic_close_file,
-	.get_file_size	= generic_get_file_size,
+	.get_file_size	= fio_sgio_get_file_size, // generic_get_file_size
 	.flags		= FIO_SYNCIO | FIO_RAWIO,
 };
 
diff --git a/io_u.c b/io_u.c
index 9f10206b..ac55b2fd 100644
--- a/io_u.c
+++ b/io_u.c
@@ -1578,6 +1578,13 @@ static void __io_u_log_error(struct thread_data *td, struct io_u *io_u)
 		io_ddir_name(io_u->ddir),
 		io_u->offset, io_u->xfer_buflen);
 
+	if (td->io_ops->errdetails) {
+		char *err = td->io_ops->errdetails(io_u);
+
+		log_err("fio: %s\n", err);
+		free(err);
+	}
+
 	if (!td->error)
 		td_verror(td, io_u->error, "io_u error");
 }
diff --git a/ioengine.h b/ioengine.h
index 3d499936..f7f3ec32 100644
--- a/ioengine.h
+++ b/ioengine.h
@@ -15,7 +15,7 @@
 #include <guasi.h>
 #endif
 
-#define FIO_IOOPS_VERSION	21
+#define FIO_IOOPS_VERSION	22
 
 enum {
 	IO_U_F_FREE		= 1 << 0,
@@ -144,6 +144,7 @@ struct ioengine_ops {
 	int (*commit)(struct thread_data *);
 	int (*getevents)(struct thread_data *, unsigned int, unsigned int, const struct timespec *);
 	struct io_u *(*event)(struct thread_data *, int);
+	char *(*errdetails)(struct io_u *);
 	int (*cancel)(struct thread_data *, struct io_u *);
 	void (*cleanup)(struct thread_data *);
 	int (*open_file)(struct thread_data *, struct fio_file *);
diff --git a/lib/strlcat.c b/lib/strlcat.c
new file mode 100644
index 00000000..643d4966
--- /dev/null
+++ b/lib/strlcat.c
@@ -0,0 +1,23 @@
+#include <string.h>
+
+size_t strlcat(char *dst, const char *src, size_t size)
+{
+	size_t dstlen;
+	size_t srclen;
+
+	dstlen = strlen(dst);
+	size -= dstlen + 1;
+
+	/* return if no room */
+	if (!size)
+		return dstlen;
+
+	srclen = strlen(src);
+	if (srclen > size)
+		srclen = size;
+
+	memcpy(dst + dstlen, src, srclen);
+	dst[dstlen + srclen] = '\0';
+
+	return dstlen + srclen;
+}
diff --git a/lib/strlcat.h b/lib/strlcat.h
new file mode 100644
index 00000000..34b668e3
--- /dev/null
+++ b/lib/strlcat.h
@@ -0,0 +1,6 @@
+#ifndef FIO_STRLCAT_H
+#define FIO_STRLCAT_h
+
+size_t strlcat(char *dst, const char *src, size_t size);
+
+#endif
diff --git a/os/os.h b/os/os.h
index f809a366..8e0b8e8f 100644
--- a/os/os.h
+++ b/os/os.h
@@ -68,6 +68,10 @@ typedef struct aiocb os_aiocb_t;
 #include "../lib/strsep.h"
 #endif
 
+#ifndef CONFIG_STRLCAT
+#include "../lib/strlcat.h"
+#endif
+
 #ifdef MSG_DONTWAIT
 #define OS_MSG_DONTWAIT	MSG_DONTWAIT
 #endif