[PATCH 3/3] st.ko: change enlarge_buffer result

[Bodo Stroesser]

From: Bodo Stroesser <bstroes...@ts.fujitsu.com>
Date: Mon, 2 Dec 2013 18:52:10 +0100
Subject: [PATCH 3/3] st.ko: change enlarge_buffer result

enlarge_buffer() just returns 1 or 0 if it could or could
not allocate the requested buffer.

In case of result 0, the callers always set the error to
EOVERFLOW. I think, this is not a good errno for those
cases, where enlarge_buffer() could not allocate the pages
it needed.

So I changed enlarge_buffer() to return a meaningful
result (-ENOMEM or -EOVERFLOW in case of error, 0 in case of
success) and the callers to use this result.

I also removed a check in setup_buffering() that is done
in enlarge_buffer() anyway.

Cc: Kai Makisara <kai.makis...@kolumbus.fi>
Signed-off-by: Bodo Stroesser <bstroes...@ts.fujitsu.com>

---

--- a/drivers/scsi/st.c 2013-12-02 18:52:10.000000000 +0100
+++ b/drivers/scsi/st.c 2013-12-02 18:52:10.000000000 +0100
@@ -1221,10 +1221,9 @@ static int st_open(struct inode *inode,
        }
 
        /* See that we have at least a one page buffer available */
-       if (!enlarge_buffer(STp->buffer, PAGE_SIZE, STp->restr_dma)) {
+       if ((retval = enlarge_buffer(STp->buffer, PAGE_SIZE, STp->restr_dma)) 
!= 0) {
                printk(KERN_WARNING "%s: Can't allocate one page tape 
buffer.\n",
                       name);
-               retval = (-EOVERFLOW);
                goto err_out;
        }
 
@@ -1517,11 +1516,9 @@ static int setup_buffering(struct scsi_t
                                clear_buffer(STbp);
                }
 
-               if (bufsize > STbp->buffer_size &&
-                   !enlarge_buffer(STbp, bufsize, STp->restr_dma)) {
+               if ((retval = enlarge_buffer(STbp, bufsize, STp->restr_dma)) != 
0) {
                        printk(KERN_WARNING "%s: Can't allocate %d byte tape 
buffer.\n",
                               tape_name(STp), bufsize);
-                       retval = (-EOVERFLOW);
                        goto out;
                }
                if (STp->block_size)
@@ -3723,7 +3720,7 @@ static int enlarge_buffer(struct st_buff
        gfp_t priority;
 
        if (new_size <= STbuffer->buffer_size)
-               return 1;
+               return 0;
 
        max_segs = STbuffer->use_sg;
 
@@ -3747,7 +3744,7 @@ static int enlarge_buffer(struct st_buff
        }
        if (max_segs * (PAGE_SIZE << order) < new_size) {
                if (order == ST_MAX_ORDER)
-                       return 0;
+                       return -EOVERFLOW;
                normalize_buffer(STbuffer);
                return enlarge_buffer(STbuffer, new_size, need_dma);
        }
@@ -3760,7 +3757,7 @@ static int enlarge_buffer(struct st_buff
                if (!page) {
                        DEB(STbuffer->buffer_size = got);
                        normalize_buffer(STbuffer);
-                       return 0;
+                       return -ENOMEM;
                }
 
                STbuffer->frp_segs += 1;
@@ -3771,7 +3768,7 @@ static int enlarge_buffer(struct st_buff
        }
        STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);
 
-       return 1;
+       return 0;
 }
 
 
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