[Qemu-devel] [v9 Patch 6/6]Qemu: raw posix implementation of reopen functions

[Supriya Kannery]

raw-posix driver changes for bdrv_reopen_xx functions to
safely reopen image files. Reopening of image files while 
changing hostcache dynamically is handled here.

Signed-off-by: Supriya Kannery <address@hidden>

Index: qemu/block/raw.c
===================================================================
--- qemu.orig/block/raw.c
+++ qemu/block/raw.c
@@ -9,6 +9,23 @@ static int raw_open(BlockDriverState *bs
     return 0;
 }
 
+static int raw_reopen_prepare(BlockDriverState *bs, BDRVReopenState **prs,
+                              int flags)
+{
+    return bdrv_reopen_prepare(bs->file, prs, flags);
+}
+
+static void raw_reopen_commit(BlockDriverState *bs, BDRVReopenState *rs,
+                              int flags)
+{
+    bdrv_reopen_commit(bs->file, rs, flags);
+}
+
+static void raw_reopen_abort(BlockDriverState *bs, BDRVReopenState *rs)
+{
+    bdrv_reopen_abort(bs->file, rs);
+}
+
 static int coroutine_fn raw_co_readv(BlockDriverState *bs, int64_t sector_num,
                                      int nb_sectors, QEMUIOVector *qiov)
 {
@@ -107,10 +124,12 @@ static BlockDriver bdrv_raw = {
 
     /* It's really 0, but we need to make g_malloc() happy */
     .instance_size      = 1,
-
     .bdrv_open          = raw_open,
+    .bdrv_reopen_prepare
+                        = raw_reopen_prepare,
+    .bdrv_reopen_commit = raw_reopen_commit,
+    .bdrv_reopen_abort  = raw_reopen_abort,
     .bdrv_close         = raw_close,
-
     .bdrv_co_readv      = raw_co_readv,
     .bdrv_co_writev     = raw_co_writev,
     .bdrv_co_flush      = raw_co_flush,
Index: qemu/block/raw-posix.c
===================================================================
--- qemu.orig/block/raw-posix.c
+++ qemu/block/raw-posix.c
@@ -136,6 +136,11 @@ typedef struct BDRVRawState {
 #endif
 } BDRVRawState;
 
+typedef struct BDRVRawReopenState {
+    int reopen_fd;
+    BDRVReopenState reopen_state;
+} BDRVRawReopenState;
+
 static int fd_open(BlockDriverState *bs);
 static int64_t raw_getlength(BlockDriverState *bs);
 
@@ -279,6 +284,70 @@ static int raw_open(BlockDriverState *bs
     return raw_open_common(bs, filename, flags, 0);
 }
 
+static int raw_reopen_prepare(BlockDriverState *bs, BDRVReopenState **prs,
+                              int flags)
+{
+    BDRVRawReopenState *raw_rs = g_malloc0(sizeof(BDRVRawReopenState));
+    BDRVRawState *s = bs->opaque;
+    int ret = 0;
+
+    raw_rs->reopen_state.reopen_flags = s->open_flags;
+    raw_rs->reopen_state.bs = bs;
+    raw_rs->reopen_fd = -1;
+    *prs = &(raw_rs->reopen_state);
+
+    /* Flags that can be set using fcntl */
+    int fcntl_flags = BDRV_O_NOCACHE;
+
+    if ((bs->open_flags & ~fcntl_flags) == (flags & ~fcntl_flags)) {
+        raw_rs->reopen_fd = dup(s->fd);
+        if (raw_rs->reopen_fd <= 0) {
+            return -1;
+        }
+        if ((flags & BDRV_O_NOCACHE)) {
+            raw_rs->reopen_state.reopen_flags |= O_DIRECT;
+        } else {
+            raw_rs->reopen_state.reopen_flags &= ~O_DIRECT;
+        }
+        ret = fcntl_setfl(raw_rs->reopen_fd, 
raw_rs->reopen_state.reopen_flags);
+    } else {
+
+        /* TBD: Handle O_DSYNC and other flags. For now return error */
+        ret = -1;
+    }
+    return ret;
+}
+
+static void raw_reopen_commit(BlockDriverState *bs, BDRVReopenState *rs,
+                              int flags)
+{
+    BDRVRawReopenState *raw_rs;
+    BDRVRawState *s = bs->opaque;
+
+    raw_rs = container_of(rs, BDRVRawReopenState, reopen_state);
+
+    /* Set new flags, so replace old fd with new one */
+    close(s->fd);
+    s->fd = raw_rs->reopen_fd;
+    s->open_flags = rs->reopen_flags;
+    bs->open_flags = flags;
+
+    g_free(raw_rs);
+
+}
+
+static void raw_reopen_abort(BlockDriverState *bs, BDRVReopenState *rs)
+{
+    BDRVRawReopenState *raw_rs;
+
+    raw_rs = container_of(rs, BDRVRawReopenState, reopen_state);
+
+    if (raw_rs->reopen_fd != -1) {
+        close(raw_rs->reopen_fd);
+    }
+    g_free(raw_rs);
+}
+
 /* XXX: use host sector size if necessary with:
 #ifdef DIOCGSECTORSIZE
         {
@@ -631,6 +700,9 @@ static BlockDriver bdrv_file = {
     .instance_size = sizeof(BDRVRawState),
     .bdrv_probe = NULL, /* no probe for protocols */
     .bdrv_file_open = raw_open,
+    .bdrv_reopen_prepare = raw_reopen_prepare,
+    .bdrv_reopen_commit = raw_reopen_commit,
+    .bdrv_reopen_abort = raw_reopen_abort,
     .bdrv_close = raw_close,
     .bdrv_create = raw_create,
     .bdrv_co_discard = raw_co_discard,