[Qemu-devel] IDE driver error handling

[andrzej zaborowski]

Hi there,
Today when I was running qemu with -snapshot and I noticed strange
things happening in the guest system after some amount of disk IO.
After some time of figuring out I found that the reason was my /tmp
partition (on the host, it is 400 MB big) being full. The guest didn't
receive any error or warning when the temporary QCOW image in /tmp
grew to 400 MB. After some investigation, it turned out that write
errors are generally ignored by the QEMU IDE driver. I came up with
the following changes to make the guest receive an IO error when that
happens. Please note that this works for me but I have little idea
about how IDE works. So I am posting this as a pointer to where the
errors really get ignored for someone who feels like fixing this in
QEMU.
Regards,
wish you a Merry Christmas
Andrew

--- qemu/hw/ide.c       2005-08-06 09:14:32.000000000 +0000
+++ qemu-warnings/hw/ide.c      2005-12-23 12:34:24.000000000 +0000
@@ -676,7 +676,9 @@
         n = s->req_nb_sectors;
     ret = bdrv_write(s->bs, sector_num, s->io_buffer, n);
     s->nsector -= n;
-    if (s->nsector == 0) {
+    if (ret) {
+        ide_abort_command(s);
+    } else if (s->nsector == 0) {
         /* no more sector to write */
         ide_transfer_stop(s);
     } else {
@@ -708,7 +710,7 @@
                             target_phys_addr_t phys_addr,
                             int transfer_size1)
 {
-    int len, transfer_size, n;
+    int len, transfer_size, n, ret;
     int64_t sector_num;

     transfer_size = transfer_size1;
@@ -717,8 +719,8 @@
         if (len == 0) {
             n = s->io_buffer_size >> 9;
             sector_num = ide_get_sector(s);
-            bdrv_write(s->bs, sector_num, s->io_buffer,
-                       s->io_buffer_size >> 9);
+            ret = bdrv_write(s->bs, sector_num, s->io_buffer,
+                             s->io_buffer_size >> 9);
             sector_num += n;
             ide_set_sector(s, sector_num);
             s->nsector -= n;
@@ -729,6 +731,11 @@
                 ide_set_irq(s);
                 return 0;
             }
+            if (ret) {
+                ide_abort_command(s);
+                ide_set_irq(s);
+                return 0;
+            }
             if (n > MAX_MULT_SECTORS)
                 n = MAX_MULT_SECTORS;
             s->io_buffer_index = 0;

--
balrog 2oo5

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