Index: block-raw-posix.c
===================================================================
--- block-raw-posix.c	(revision 5304)
+++ block-raw-posix.c	(working copy)
@@ -84,10 +84,20 @@
    reopen it to see if the disk has been changed */
 #define FD_OPEN_TIMEOUT 1000
 
+#define RAW_FD_POOL_SIZE	4
+
+typedef struct RawFdPoolEntry
+{
+    int fd;
+    int inuse;
+} RawFdPoolEntry;
+
 typedef struct BDRVRawState {
     int fd;
     int type;
     unsigned int lseek_err_cnt;
+    int fd0_inuse;
+    RawFdPoolEntry fd_pool[RAW_FD_POOL_SIZE];
 #if defined(__linux__)
     /* linux floppy specific */
     int fd_open_flags;
@@ -109,6 +119,7 @@
 {
     BDRVRawState *s = bs->opaque;
     int fd, open_flags, ret;
+    int i;
 
     posix_aio_init();
 
@@ -138,6 +149,11 @@
         return ret;
     }
     s->fd = fd;
+    for (i = 0; i < RAW_FD_POOL_SIZE; i++) {
+        s->fd_pool[i].fd = -1;
+        s->fd_pool[i].inuse = 0;
+    }
+    s->fd0_inuse = 0;
 #if defined(O_DIRECT)
     s->aligned_buf = NULL;
     if (flags & BDRV_O_DIRECT) {
@@ -436,6 +452,7 @@
 
 typedef struct RawAIOCB {
     BlockDriverAIOCB common;
+    int fd;
     struct aiocb aiocb;
     struct RawAIOCB *next;
     int ret;
@@ -447,6 +464,52 @@
     RawAIOCB *first_aio;
 } PosixAioState;
 
+static int raw_fd_pool_get(BDRVRawState *s)
+{
+    if (s->fd0_inuse) {
+        int i;
+
+        for (i = 0; i < RAW_FD_POOL_SIZE; i++) {
+            if (s->fd_pool[i].fd == -1) {
+                s->fd_pool[i].fd = dup(s->fd);
+                if (s->fd_pool[i].fd == -1)
+                    continue;
+                s->fd_pool[i].inuse = 0;
+            }
+
+            if (!s->fd_pool[i].inuse) {
+                s->fd_pool[i].inuse++;
+                return s->fd_pool[i].fd;
+            }
+        }
+    }
+    s->fd0_inuse++;
+
+    return s->fd;
+}
+
+static void raw_fd_pool_put(RawAIOCB *acb)
+{
+    BDRVRawState *s = acb->common.bs->opaque;
+    int fd = acb->fd;
+    int i;
+
+    if (s->fd == fd) {
+        s->fd0_inuse--;
+        return;
+    }
+
+    for (i = 0; i < RAW_FD_POOL_SIZE; i++) {
+        if (s->fd_pool[i].fd == fd) {
+            s->fd_pool[i].inuse--;
+            if (s->fd_pool[i].inuse == 0) {
+                close(s->fd_pool[i].fd);
+                s->fd_pool[i].fd = -1;
+            }
+        }
+    }
+}
+
 static void posix_aio_read(void *opaque)
 {
     PosixAioState *s = opaque;
@@ -487,6 +550,7 @@
             if (ret == ECANCELED) {
                 /* remove the request */
                 *pacb = acb->next;
+                raw_fd_pool_put(acb);
                 qemu_aio_release(acb);
             } else if (ret != EINPROGRESS) {
                 /* end of aio */
@@ -503,6 +567,7 @@
                 *pacb = acb->next;
                 /* call the callback */
                 acb->common.cb(acb->common.opaque, ret);
+                raw_fd_pool_put(acb);
                 qemu_aio_release(acb);
                 break;
             } else {
@@ -575,7 +640,8 @@
     acb = qemu_aio_get(bs, cb, opaque);
     if (!acb)
         return NULL;
-    acb->aiocb.aio_fildes = s->fd;
+    acb->fd = raw_fd_pool_get(s);
+    acb->aiocb.aio_fildes = acb->fd;
     acb->aiocb.aio_sigevent.sigev_signo = SIGUSR2;
     acb->aiocb.aio_sigevent.sigev_notify = SIGEV_SIGNAL;
     acb->aiocb.aio_buf = buf;
@@ -682,6 +748,7 @@
             break;
         } else if (*pacb == acb) {
             *pacb = acb->next;
+            raw_fd_pool_put(acb);
             qemu_aio_release(acb);
             break;
         }
@@ -698,6 +765,7 @@
 static void raw_close(BlockDriverState *bs)
 {
     BDRVRawState *s = bs->opaque;
+    int i;
     if (s->fd >= 0) {
         close(s->fd);
         s->fd = -1;
@@ -706,6 +774,10 @@
             qemu_free(s->aligned_buf);
 #endif
     }
+    for (i = 0; i < RAW_FD_POOL_SIZE; i++) {
+        if (s->fd_pool[i].fd != -1)
+            close(s->fd_pool[i].fd);
+    } 
 }
 
 static int raw_truncate(BlockDriverState *bs, int64_t offset)
@@ -973,6 +1045,18 @@
 }
 
 #if defined(__linux__)
+static void raw_invalidate_fd_pool(BDRVRawState *s)
+{
+    int i;
+    for (i = 0; i < RAW_FD_POOL_SIZE; i++) {
+        if (s->fd_pool[i].fd != -1) {
+            close(s->fd_pool[i].fd);
+            s->fd_pool[i].fd = -1;
+            s->fd_pool[i].inuse = 0;
+        }
+    }
+    s->fd0_inuse = 0;
+}
 
 /* Note: we do not have a reliable method to detect if the floppy is
    present. The current method is to try to open the floppy at every
@@ -989,6 +1073,7 @@
         (qemu_get_clock(rt_clock) - s->fd_open_time) >= FD_OPEN_TIMEOUT) {
         close(s->fd);
         s->fd = -1;
+        raw_invalidate_fd_pool(s);
 #ifdef DEBUG_FLOPPY
         printf("Floppy closed\n");
 #endif
@@ -1089,6 +1174,7 @@
             if (s->fd >= 0) {
                 close(s->fd);
                 s->fd = -1;
+                raw_invalidate_fd_pool(s);
             }
             fd = open(bs->filename, s->fd_open_flags | O_NONBLOCK);
             if (fd >= 0) {