This patch cleans up quite a few code paths by optimizing for the
scatter-gather case.  Experiments reveal that a mount/read/write/umount
cycle will use thousands of s-g requests and less than 10 non-sg requests,
so this is a legitimate trade off for performance.

Greg, please apply.

As noted, this patch also exposes some places that need fixes.  Patches to
follow.

Matt

----- Forwarded message from Alan Stern <[EMAIL PROTECTED]> -----

Date: Fri, 5 Dec 2003 12:10:33 -0500 (EST)
From: Alan Stern <[EMAIL PROTECTED]>
Subject: PATCH: (as152)  Remove non s-g pathway from subdriver READ/WRITE
To: Matthew Dharm <[EMAIL PROTECTED]>
cc: USB Storage List <[EMAIL PROTECTED]>
X-Spam-Status: No, hits=-1.6 required=5.0
        tests=AWL,BALANCE_FOR_LONG_20K,PATCH_UNIFIED_DIFF,
              SPAM_PHRASE_00_01,USER_AGENT_PINE
        version=2.44

Matt:

This patch does what you suggested.  The read/write routines from the
updated subdrivers are changed so they don't bother to differentiate
between transfers that do or do not use scatter-gather.  The low-level
usb_stor_access_xfer_buf routine will Do The Right Thing regardless, and
there probably won't ever be more than a few non s-g calls.  (What about
filesystem I/O requests to access metadata?)

It turns out that in addition to removing some comments and a few tests, 
this change allowed me to remove the buffer and use_sg arguments passed to 
the read/write routines as well.  So the simplification ended up being a 
bit bigger than I expected.

While writing this patch, I noticed spots in several drivers that still
need to be changed -- they slipped past me before.  These drivers handle
things like READ-CAPACITY or REQUEST-SENSE by copying the data directly to 
srb->request_buffer, which is obviously wrong if s-g is being used.  I'll 
send in changes next week that convert them to use the 
usb_stor_set_xfer_buf function.  Like you said, it's going to be handy in 
more places than originally intended!

Alan Stern


--- a/drivers/usb/storage2/datafab.c    Fri Dec  5 11:07:49 2003
+++ a/drivers/usb/storage/datafab.c     Fri Dec  5 11:42:27 2003
@@ -89,11 +89,10 @@
 static int datafab_read_data(struct us_data *us,
                             struct datafab_info *info,
                             u32 sector,
-                            u32 sectors, 
-                            unsigned char *buffer, 
-                            int use_sg)
+                            u32 sectors)
 {
        unsigned char *command = us->iobuf;
+       unsigned char *buffer;
        unsigned char  thistime;
        unsigned int totallen, alloclen;
        int len, result;
@@ -116,18 +115,13 @@
        totallen = sectors * info->ssize;
 
        // Since we don't read more than 64 KB at a time, we have to create
-       // a bounce buffer if the transfer uses scatter-gather.  We will
-       // move the data a piece at a time between the bounce buffer and
-       // the actual transfer buffer.  If we're not using scatter-gather,
-       // we can simply update the transfer buffer pointer to get the
-       // same effect.
+       // a bounce buffer and move the data a piece at a time between the
+       // bounce buffer and the actual transfer buffer.
 
        alloclen = min(totallen, 65536u);
-       if (use_sg) {
-               buffer = kmalloc(alloclen, GFP_NOIO);
-               if (buffer == NULL)
-                       return USB_STOR_TRANSPORT_ERROR;
-       }
+       buffer = kmalloc(alloclen, GFP_NOIO);
+       if (buffer == NULL)
+               return USB_STOR_TRANSPORT_ERROR;
 
        do {
                // loop, never allocate or transfer more than 64k at once
@@ -157,24 +151,19 @@
                if (result != USB_STOR_XFER_GOOD)
                        goto leave;
 
-               // Store the data (s-g) or update the pointer (!s-g)
-               if (use_sg)
-                       usb_stor_access_xfer_buf(buffer, len, us->srb,
-                                        &sg_idx, &sg_offset, TO_XFER_BUF);
-               else
-                       buffer += len;
+               // Store the data in the transfer buffer
+               usb_stor_access_xfer_buf(buffer, len, us->srb,
+                                &sg_idx, &sg_offset, TO_XFER_BUF);
 
                sector += thistime;
                totallen -= len;
        } while (totallen > 0);
 
-       if (use_sg)
-               kfree(buffer);
+       kfree(buffer);
        return USB_STOR_TRANSPORT_GOOD;
 
  leave:
-       if (use_sg)
-               kfree(buffer);
+       kfree(buffer);
        return USB_STOR_TRANSPORT_ERROR;
 }
 
@@ -182,12 +171,11 @@
 static int datafab_write_data(struct us_data *us,
                              struct datafab_info *info,
                              u32 sector,
-                             u32 sectors, 
-                             unsigned char *buffer, 
-                             int use_sg)
+                             u32 sectors)
 {
        unsigned char *command = us->iobuf;
        unsigned char *reply = us->iobuf;
+       unsigned char *buffer;
        unsigned char thistime;
        unsigned int totallen, alloclen;
        int len, result;
@@ -210,18 +198,13 @@
        totallen = sectors * info->ssize;
 
        // Since we don't write more than 64 KB at a time, we have to create
-       // a bounce buffer if the transfer uses scatter-gather.  We will
-       // move the data a piece at a time between the bounce buffer and
-       // the actual transfer buffer.  If we're not using scatter-gather,
-       // we can simply update the transfer buffer pointer to get the
-       // same effect.
+       // a bounce buffer and move the data a piece at a time between the
+       // bounce buffer and the actual transfer buffer.
 
        alloclen = min(totallen, 65536u);
-       if (use_sg) {
-               buffer = kmalloc(alloclen, GFP_NOIO);
-               if (buffer == NULL)
-                       return USB_STOR_TRANSPORT_ERROR;
-       }
+       buffer = kmalloc(alloclen, GFP_NOIO);
+       if (buffer == NULL)
+               return USB_STOR_TRANSPORT_ERROR;
 
        do {
                // loop, never allocate or transfer more than 64k at once
@@ -230,10 +213,9 @@
                len = min(totallen, alloclen);
                thistime = (len / info->ssize) & 0xff;
 
-               // Get the data from the transfer buffer (s-g)
-               if (use_sg)
-                       usb_stor_access_xfer_buf(buffer, len, us->srb,
-                                       &sg_idx, &sg_offset, FROM_XFER_BUF);
+               // Get the data from the transfer buffer
+               usb_stor_access_xfer_buf(buffer, len, us->srb,
+                               &sg_idx, &sg_offset, FROM_XFER_BUF);
 
                command[0] = 0;
                command[1] = thistime;
@@ -269,21 +251,15 @@
                        goto leave;
                }
 
-               // Update the transfer buffer pointer (!s-g)
-               if (!use_sg)
-                       buffer += len;
-
                sector += thistime;
                totallen -= len;
        } while (totallen > 0);
 
-       if (use_sg)
-               kfree(buffer);
+       kfree(buffer);
        return USB_STOR_TRANSPORT_GOOD;
 
  leave:
-       if (use_sg)
-               kfree(buffer);
+       kfree(buffer);
        return USB_STOR_TRANSPORT_ERROR;
 }
 
@@ -615,7 +591,7 @@
                blocks = ((u32)(srb->cmnd[7]) << 8) | ((u32)(srb->cmnd[8]));
 
                US_DEBUGP("datafab_transport:  READ_10: read block 0x%04lx  count 
%ld\n", block, blocks);
-               return datafab_read_data(us, info, block, blocks, ptr, srb->use_sg);
+               return datafab_read_data(us, info, block, blocks);
        }
 
        if (srb->cmnd[0] == READ_12) {
@@ -628,7 +604,7 @@
                         ((u32)(srb->cmnd[8]) <<  8) | ((u32)(srb->cmnd[9]));
 
                US_DEBUGP("datafab_transport:  READ_12: read block 0x%04lx  count 
%ld\n", block, blocks);
-               return datafab_read_data(us, info, block, blocks, ptr, srb->use_sg);
+               return datafab_read_data(us, info, block, blocks);
        }
 
        if (srb->cmnd[0] == WRITE_10) {
@@ -638,7 +614,7 @@
                blocks = ((u32)(srb->cmnd[7]) << 8) | ((u32)(srb->cmnd[8]));
 
                US_DEBUGP("datafab_transport:  WRITE_10: write block 0x%04lx  count 
%ld\n", block, blocks);
-               return datafab_write_data(us, info, block, blocks, ptr, srb->use_sg);
+               return datafab_write_data(us, info, block, blocks);
        }
 
        if (srb->cmnd[0] == WRITE_12) {
@@ -651,7 +627,7 @@
                         ((u32)(srb->cmnd[8]) <<  8) | ((u32)(srb->cmnd[9]));
 
                US_DEBUGP("datafab_transport:  WRITE_12: write block 0x%04lx  count 
%ld\n", block, blocks);
-               return datafab_write_data(us, info, block, blocks, ptr, srb->use_sg);
+               return datafab_write_data(us, info, block, blocks);
        }
 
        if (srb->cmnd[0] == TEST_UNIT_READY) {
--- a/drivers/usb/storage2/jumpshot.c   Fri Dec  5 11:07:49 2003
+++ a/drivers/usb/storage/jumpshot.c    Fri Dec  5 11:42:57 2003
@@ -109,11 +109,10 @@
 static int jumpshot_read_data(struct us_data *us,
                              struct jumpshot_info *info,
                              u32 sector,
-                             u32 sectors, 
-                             unsigned char *buffer, 
-                             int use_sg)
+                             u32 sectors)
 {
        unsigned char *command = us->iobuf;
+       unsigned char *buffer;
        unsigned char  thistime;
        unsigned int totallen, alloclen;
        int len, result;
@@ -130,18 +129,13 @@
        totallen = sectors * info->ssize;
 
        // Since we don't read more than 64 KB at a time, we have to create
-       // a bounce buffer if the transfer uses scatter-gather.  We will
-       // move the data a piece at a time between the bounce buffer and
-       // the actual transfer buffer.  If we're not using scatter-gather,
-       // we can simply update the transfer buffer pointer to get the
-       // same effect.
+       // a bounce buffer and move the data a piece at a time between the
+       // bounce buffer and the actual transfer buffer.
 
        alloclen = min(totallen, 65536u);
-       if (use_sg) {
-               buffer = kmalloc(alloclen, GFP_NOIO);
-               if (buffer == NULL)
-                       return USB_STOR_TRANSPORT_ERROR;
-       }
+       buffer = kmalloc(alloclen, GFP_NOIO);
+       if (buffer == NULL)
+               return USB_STOR_TRANSPORT_ERROR;
 
        do {
                // loop, never allocate or transfer more than 64k at once
@@ -171,24 +165,19 @@
 
                US_DEBUGP("jumpshot_read_data:  %d bytes\n", len);
 
-               // Store the data (s-g) or update the pointer (!s-g)
-               if (use_sg)
-                       usb_stor_access_xfer_buf(buffer, len, us->srb,
-                                        &sg_idx, &sg_offset, TO_XFER_BUF);
-               else
-                       buffer += len;
+               // Store the data in the transfer buffer
+               usb_stor_access_xfer_buf(buffer, len, us->srb,
+                                &sg_idx, &sg_offset, TO_XFER_BUF);
 
                sector += thistime;
                totallen -= len;
        } while (totallen > 0);
 
-       if (use_sg)
-               kfree(buffer);
+       kfree(buffer);
        return USB_STOR_TRANSPORT_GOOD;
 
  leave:
-       if (use_sg)
-               kfree(buffer);
+       kfree(buffer);
        return USB_STOR_TRANSPORT_ERROR;
 }
 
@@ -196,11 +185,10 @@
 static int jumpshot_write_data(struct us_data *us,
                               struct jumpshot_info *info,
                               u32 sector,
-                              u32 sectors, 
-                              unsigned char *buffer, 
-                              int use_sg)
+                              u32 sectors)
 {
        unsigned char *command = us->iobuf;
+       unsigned char *buffer;
        unsigned char  thistime;
        unsigned int totallen, alloclen;
        int len, result, waitcount;
@@ -217,18 +205,13 @@
        totallen = sectors * info->ssize;
 
        // Since we don't write more than 64 KB at a time, we have to create
-       // a bounce buffer if the transfer uses scatter-gather.  We will
-       // move the data a piece at a time between the bounce buffer and
-       // the actual transfer buffer.  If we're not using scatter-gather,
-       // we can simply update the transfer buffer pointer to get the
-       // same effect.
+       // a bounce buffer and move the data a piece at a time between the
+       // bounce buffer and the actual transfer buffer.
 
        alloclen = min(totallen, 65536u);
-       if (use_sg) {
-               buffer = kmalloc(alloclen, GFP_NOIO);
-               if (buffer == NULL)
-                       return USB_STOR_TRANSPORT_ERROR;
-       }
+       buffer = kmalloc(alloclen, GFP_NOIO);
+       if (buffer == NULL)
+               return USB_STOR_TRANSPORT_ERROR;
 
        do {
                // loop, never allocate or transfer more than 64k at once
@@ -237,10 +220,9 @@
                len = min(totallen, alloclen);
                thistime = (len / info->ssize) & 0xff;
 
-               // Get the data from the transfer buffer (s-g)
-               if (use_sg)
-                       usb_stor_access_xfer_buf(buffer, len, us->srb,
-                                       &sg_idx, &sg_offset, FROM_XFER_BUF);
+               // Get the data from the transfer buffer
+               usb_stor_access_xfer_buf(buffer, len, us->srb,
+                               &sg_idx, &sg_offset, FROM_XFER_BUF);
 
                command[0] = 0;
                command[1] = thistime;
@@ -278,21 +260,15 @@
                if (result != USB_STOR_TRANSPORT_GOOD)
                        US_DEBUGP("jumpshot_write_data:  Gah!  Waitcount = 10.  Bad 
write!?\n");
 
-               // Update the transfer buffer pointer (!s-g)
-               if (!use_sg)
-                       buffer += len;
-
                sector += thistime;
                totallen -= len;
        } while (totallen > 0);
 
-       if (use_sg)
-               kfree(buffer);
+       kfree(buffer);
        return result;
 
  leave:
-       if (use_sg)
-               kfree(buffer);
+       kfree(buffer);
        return USB_STOR_TRANSPORT_ERROR;
 }
 
@@ -546,7 +522,7 @@
                blocks = ((u32)(srb->cmnd[7]) << 8) | ((u32)(srb->cmnd[8]));
 
                US_DEBUGP("jumpshot_transport:  READ_10: read block 0x%04lx  count 
%ld\n", block, blocks);
-               return jumpshot_read_data(us, info, block, blocks, ptr, srb->use_sg);
+               return jumpshot_read_data(us, info, block, blocks);
        }
 
        if (srb->cmnd[0] == READ_12) {
@@ -559,7 +535,7 @@
                         ((u32)(srb->cmnd[8]) <<  8) | ((u32)(srb->cmnd[9]));
 
                US_DEBUGP("jumpshot_transport:  READ_12: read block 0x%04lx  count 
%ld\n", block, blocks);
-               return jumpshot_read_data(us, info, block, blocks, ptr, srb->use_sg);
+               return jumpshot_read_data(us, info, block, blocks);
        }
 
        if (srb->cmnd[0] == WRITE_10) {
@@ -569,7 +545,7 @@
                blocks = ((u32)(srb->cmnd[7]) << 8) | ((u32)(srb->cmnd[8]));
 
                US_DEBUGP("jumpshot_transport:  WRITE_10: write block 0x%04lx  count 
%ld\n", block, blocks);
-               return jumpshot_write_data(us, info, block, blocks, ptr, srb->use_sg);
+               return jumpshot_write_data(us, info, block, blocks);
        }
 
        if (srb->cmnd[0] == WRITE_12) {
@@ -582,7 +558,7 @@
                         ((u32)(srb->cmnd[8]) <<  8) | ((u32)(srb->cmnd[9]));
 
                US_DEBUGP("jumpshot_transport:  WRITE_12: write block 0x%04lx  count 
%ld\n", block, blocks);
-               return jumpshot_write_data(us, info, block, blocks, ptr, srb->use_sg);
+               return jumpshot_write_data(us, info, block, blocks);
        }
 
 
--- a/drivers/usb/storage2/sddr09.c     Fri Dec  5 11:07:49 2003
+++ a/drivers/usb/storage/sddr09.c      Fri Dec  5 11:44:48 2003
@@ -662,31 +662,24 @@
 static int
 sddr09_read_data(struct us_data *us,
                 unsigned long address,
-                unsigned int sectors,
-                unsigned char *buffer,
-                int use_sg) {
+                unsigned int sectors) {
 
        struct sddr09_card_info *info = (struct sddr09_card_info *) us->extra;
+       unsigned char *buffer;
        unsigned int lba, maxlba, pba;
        unsigned int page, pages;
        unsigned int len, index, offset;
        int result;
 
        // Since we only read in one block at a time, we have to create
-       // a bounce buffer if the transfer uses scatter-gather.  We will
-       // move the data a piece at a time between the bounce buffer and
-       // the actual transfer buffer.  If we're not using scatter-gather,
-       // we can simply update the transfer buffer pointer to get the
-       // same effect.
-
-       if (use_sg) {
-               len = min(sectors, (unsigned int) info->blocksize) *
-                               info->pagesize;
-               buffer = kmalloc(len, GFP_NOIO);
-               if (buffer == NULL) {
-                       printk("sddr09_read_data: Out of memory\n");
-                       return USB_STOR_TRANSPORT_ERROR;
-               }
+       // a bounce buffer and move the data a piece at a time between the
+       // bounce buffer and the actual transfer buffer.
+
+       len = min(sectors, (unsigned int) info->blocksize) * info->pagesize;
+       buffer = kmalloc(len, GFP_NOIO);
+       if (buffer == NULL) {
+               printk("sddr09_read_data: Out of memory\n");
+               return USB_STOR_TRANSPORT_ERROR;
        }
 
        // Figure out the initial LBA and page
@@ -743,21 +736,16 @@
                                break;
                }
 
-               // Store the data (s-g) or update the pointer (!s-g)
-               if (use_sg)
-                       usb_stor_access_xfer_buf(buffer, len, us->srb,
-                                       &index, &offset, TO_XFER_BUF);
-               else
-                       buffer += len;
+               // Store the data in the transfer buffer
+               usb_stor_access_xfer_buf(buffer, len, us->srb,
+                               &index, &offset, TO_XFER_BUF);
 
                page = 0;
                lba++;
                sectors -= pages;
        }
 
-       if (use_sg)
-               kfree(buffer);
-
+       kfree(buffer);
        return result;
 }
 
@@ -897,14 +885,13 @@
 static int
 sddr09_write_data(struct us_data *us,
                  unsigned long address,
-                 unsigned int sectors,
-                 unsigned char *buffer,
-                 int use_sg) {
+                 unsigned int sectors) {
 
        struct sddr09_card_info *info = (struct sddr09_card_info *) us->extra;
        unsigned int lba, page, pages;
        unsigned int pagelen, blocklen;
        unsigned char *blockbuffer;
+       unsigned char *buffer;
        unsigned int len, index, offset;
        int result;
 
@@ -923,21 +910,15 @@
        }
 
        // Since we don't write the user data directly to the device,
-       // we have to create a bounce buffer if the transfer uses
-       // scatter-gather.  We will move the data a piece at a time
-       // between the bounce buffer and the actual transfer buffer.
-       // If we're not using scatter-gather, we can simply update
-       // the transfer buffer pointer to get the same effect.
-
-       if (use_sg) {
-               len = min(sectors, (unsigned int) info->blocksize) *
-                               info->pagesize;
-               buffer = kmalloc(len, GFP_NOIO);
-               if (buffer == NULL) {
-                       printk("sddr09_write_data: Out of memory\n");
-                       kfree(blockbuffer);
-                       return USB_STOR_TRANSPORT_ERROR;
-               }
+       // we have to create a bounce buffer and move the data a piece
+       // at a time between the bounce buffer and the actual transfer buffer.
+
+       len = min(sectors, (unsigned int) info->blocksize) * info->pagesize;
+       buffer = kmalloc(len, GFP_NOIO);
+       if (buffer == NULL) {
+               printk("sddr09_write_data: Out of memory\n");
+               kfree(blockbuffer);
+               return USB_STOR_TRANSPORT_ERROR;
        }
 
        // Figure out the initial LBA and page
@@ -954,27 +935,21 @@
                pages = min(sectors, info->blocksize - page);
                len = (pages << info->pageshift);
 
-               // Get the data from the transfer buffer (s-g)
-               if (use_sg)
-                       usb_stor_access_xfer_buf(buffer, len, us->srb,
-                                       &index, &offset, FROM_XFER_BUF);
+               // Get the data from the transfer buffer
+               usb_stor_access_xfer_buf(buffer, len, us->srb,
+                               &index, &offset, FROM_XFER_BUF);
 
                result = sddr09_write_lba(us, lba, page, pages,
                                buffer, blockbuffer);
                if (result != USB_STOR_TRANSPORT_GOOD)
                        break;
 
-               // Update the transfer buffer pointer (!s-g)
-               if (!use_sg)
-                       buffer += len;
-
                page = 0;
                lba++;
                sectors -= pages;
        }
 
-       if (use_sg)
-               kfree(buffer);
+       kfree(buffer);
        kfree(blockbuffer);
 
        return result;
@@ -1544,7 +1519,7 @@
                US_DEBUGP("READ_10: read page %d pagect %d\n",
                          page, pages);
 
-               return sddr09_read_data(us, page, pages, ptr, srb->use_sg);
+               return sddr09_read_data(us, page, pages);
        }
 
        if (srb->cmnd[0] == WRITE_10) {
@@ -1557,7 +1532,7 @@
                US_DEBUGP("WRITE_10: write page %d pagect %d\n",
                          page, pages);
 
-               return sddr09_write_data(us, page, pages, ptr, srb->use_sg);
+               return sddr09_write_data(us, page, pages);
        }
 
        // Pass TEST_UNIT_READY and REQUEST_SENSE through
--- a/drivers/usb/storage2/sddr55.c     Fri Dec  5 11:07:49 2003
+++ a/drivers/usb/storage/sddr55.c      Fri Dec  5 11:45:23 2003
@@ -153,14 +153,13 @@
 static int sddr55_read_data(struct us_data *us,
                unsigned int lba,
                unsigned int page,
-               unsigned short sectors,
-               unsigned char *buffer,
-               int use_sg) {
+               unsigned short sectors) {
 
        int result = USB_STOR_TRANSPORT_GOOD;
        unsigned char *command = us->iobuf;
        unsigned char *status = us->iobuf;
        struct sddr55_card_info *info = (struct sddr55_card_info *)us->extra;
+       unsigned char *buffer;
 
        unsigned int pba;
        unsigned long address;
@@ -169,20 +168,14 @@
        unsigned int len, index, offset;
 
        // Since we only read in one block at a time, we have to create
-       // a bounce buffer if the transfer uses scatter-gather.  We will
-       // move the data a piece at a time between the bounce buffer and
-       // the actual transfer buffer.  If we're not using scatter-gather,
-       // we can simply update the transfer buffer pointer to get the
-       // same effect.
-
-       if (use_sg) {
-               len = min((unsigned int) sectors,
-                               (unsigned int) info->blocksize >>
-                                       info->smallpageshift) * PAGESIZE;
-               buffer = kmalloc(len, GFP_NOIO);
-               if (buffer == NULL)
-                       return USB_STOR_TRANSPORT_ERROR; /* out of memory */
-       }
+       // a bounce buffer and move the data a piece at a time between the
+       // bounce buffer and the actual transfer buffer.
+
+       len = min((unsigned int) sectors, (unsigned int) info->blocksize >>
+                       info->smallpageshift) * PAGESIZE;
+       buffer = kmalloc(len, GFP_NOIO);
+       if (buffer == NULL)
+               return USB_STOR_TRANSPORT_ERROR; /* out of memory */
        index = offset = 0;
 
        while (sectors>0) {
@@ -258,12 +251,9 @@
                        }
                }
 
-               // Store the data (s-g) or update the pointer (!s-g)
-               if (use_sg)
-                       usb_stor_access_xfer_buf(buffer, len, us->srb,
-                                       &index, &offset, TO_XFER_BUF);
-               else
-                       buffer += len;
+               // Store the data in the transfer buffer
+               usb_stor_access_xfer_buf(buffer, len, us->srb,
+                               &index, &offset, TO_XFER_BUF);
 
                page = 0;
                lba++;
@@ -273,8 +263,7 @@
        result = USB_STOR_TRANSPORT_GOOD;
 
 leave:
-       if (use_sg)
-               kfree(buffer);
+       kfree(buffer);
 
        return result;
 }
@@ -282,14 +271,13 @@
 static int sddr55_write_data(struct us_data *us,
                unsigned int lba,
                unsigned int page,
-               unsigned short sectors,
-               unsigned char *buffer,
-               int use_sg) {
+               unsigned short sectors) {
 
        int result = USB_STOR_TRANSPORT_GOOD;
        unsigned char *command = us->iobuf;
        unsigned char *status = us->iobuf;
        struct sddr55_card_info *info = (struct sddr55_card_info *)us->extra;
+       unsigned char *buffer;
 
        unsigned int pba;
        unsigned int new_pba;
@@ -306,20 +294,14 @@
        }
 
        // Since we only write one block at a time, we have to create
-       // a bounce buffer if the transfer uses scatter-gather.  We will
-       // move the data a piece at a time between the bounce buffer and
-       // the actual transfer buffer.  If we're not using scatter-gather,
-       // we can simply update the transfer buffer pointer to get the
-       // same effect.
-
-       if (use_sg) {
-               len = min((unsigned int) sectors,
-                               (unsigned int) info->blocksize >>
-                                       info->smallpageshift) * PAGESIZE;
-               buffer = kmalloc(len, GFP_NOIO);
-               if (buffer == NULL)
-                       return USB_STOR_TRANSPORT_ERROR;
-       }
+       // a bounce buffer and move the data a piece at a time between the
+       // bounce buffer and the actual transfer buffer.
+
+       len = min((unsigned int) sectors, (unsigned int) info->blocksize >>
+                       info->smallpageshift) * PAGESIZE;
+       buffer = kmalloc(len, GFP_NOIO);
+       if (buffer == NULL)
+               return USB_STOR_TRANSPORT_ERROR;
        index = offset = 0;
 
        while (sectors > 0) {
@@ -336,10 +318,9 @@
                                info->blocksize - page);
                len = pages << info->pageshift;
 
-               // Get the data from the transfer buffer (s-g)
-               if (use_sg)
-                       usb_stor_access_xfer_buf(buffer, len, us->srb,
-                                       &index, &offset, FROM_XFER_BUF);
+               // Get the data from the transfer buffer
+               usb_stor_access_xfer_buf(buffer, len, us->srb,
+                               &index, &offset, FROM_XFER_BUF);
 
                US_DEBUGP("Write %02X pages, to PBA %04X"
                        " (LBA %04X) page %02X\n",
@@ -480,9 +461,6 @@
                /* update the pba<->lba maps for new_pba */
                info->pba_to_lba[new_pba] = lba % 1000;
 
-               // Update the transfer buffer pointer (!s-g)
-               if (!use_sg)
-                       buffer += len;
                page = 0;
                lba++;
                sectors -= pages >> info->smallpageshift;
@@ -490,8 +468,7 @@
        result = USB_STOR_TRANSPORT_GOOD;
 
  leave:
-       if (use_sg)
-               kfree(buffer);
+       kfree(buffer);
        return result;
 }
 
@@ -963,13 +940,13 @@
                                " pages %d\n",
                                pba, lba, page, pages);
 
-                       return sddr55_write_data(us, lba, page, pages, ptr, 
srb->use_sg);
+                       return sddr55_write_data(us, lba, page, pages);
                } else {
                        US_DEBUGP("READ_10: read block %04X (LBA %04X) page %01X"
                                " pages %d\n",
                                pba, lba, page, pages);
 
-                       return sddr55_read_data(us, lba, page, pages, ptr, 
srb->use_sg);
+                       return sddr55_read_data(us, lba, page, pages);
                }
        }
 
--- a/drivers/usb/storage2/shuttle_usbat.c      Fri Dec  5 11:07:49 2003
+++ a/drivers/usb/storage/shuttle_usbat.c       Fri Dec  5 11:26:34 2003
@@ -569,21 +569,15 @@
        }
 
        // Since we only read in one block at a time, we have to create
-       // a bounce buffer if the transfer uses scatter-gather.  We will
-       // move the data a piece at a time between the bounce buffer and
-       // the actual transfer buffer.  If we're not using scatter-gather,
-       // we can simply update the transfer buffer pointer to get the
-       // same effect.
+       // a bounce buffer and move the data a piece at a time between the
+       // bounce buffer and the actual transfer buffer.
 
        len = (65535/srb->transfersize) * srb->transfersize;
        US_DEBUGP("Max read is %d bytes\n", len);
        len = min(len, srb->request_bufflen);
-       if (srb->use_sg) {
-               buffer = kmalloc(len, GFP_NOIO);
-               if (buffer == NULL) // bloody hell!
-                       return USB_STOR_TRANSPORT_FAILED;
-       } else
-               buffer = srb->request_buffer;
+       buffer = kmalloc(len, GFP_NOIO);
+       if (buffer == NULL) // bloody hell!
+               return USB_STOR_TRANSPORT_FAILED;
        sector = short_pack(data[7+3], data[7+2]);
        sector <<= 16;
        sector |= short_pack(data[7+5], data[7+4]);
@@ -621,12 +615,9 @@
                if (result != USB_STOR_TRANSPORT_GOOD)
                        break;
 
-               // Store the data (s-g) or update the pointer (!s-g)
-               if (srb->use_sg)
-                       usb_stor_access_xfer_buf(buffer, len, srb,
-                                        &sg_segment, &sg_offset, TO_XFER_BUF);
-               else
-                       buffer += len;
+               // Store the data in the transfer buffer
+               usb_stor_access_xfer_buf(buffer, len, srb,
+                                &sg_segment, &sg_offset, TO_XFER_BUF);
 
                // Update the amount transferred and the sector number
 
@@ -635,8 +626,7 @@
 
        } // while transferred != srb->request_bufflen
 
-       if (srb->use_sg)
-               kfree(buffer);
+       kfree(buffer);
        return result;
 }
 

----- End forwarded message -----

-- 
Matthew Dharm                              Home: [EMAIL PROTECTED] 
Maintainer, Linux USB Mass Storage Driver

C:  Like the Furby?
DP: He gives me the creeps.  Think the SPCA will take him?
                                        -- Cobb and Dust Puppy
User Friendly, 1/2/1999

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