On 07/30/2012 05:34 PM, Supriya Kannery wrote:
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 <supri...@linux.vnet.ibm.com>
---
Index: qemu/block/raw.c
===================================================================
--- qemu.orig/block/raw.c
+++ qemu/block/raw.c
@@ -9,6 +9,22 @@ 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)
+{
+ bdrv_reopen_commit(bs->file, rs);
+}
+
+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)
{
@@ -113,6 +129,10 @@ static BlockDriver bdrv_raw = {
.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,
Index: qemu/block/raw-posix.c
===================================================================
--- qemu.orig/block/raw-posix.c
+++ qemu/block/raw-posix.c
@@ -140,8 +140,15 @@ typedef struct BDRVRawState {
#endif
} BDRVRawState;
+typedef struct BDRVRawReopenState {
+ BDRVReopenState reopen_state;
+ BDRVRawState *stash_s;
+} BDRVRawReopenState;
+
static int fd_open(BlockDriverState *bs);
static int64_t raw_getlength(BlockDriverState *bs);
+static void raw_stash_state(BDRVRawState *stashed_state, BDRVRawState *s);
+static void raw_revert_state(BDRVRawState *s, BDRVRawState *stashed_state);
#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
static int cdrom_reopen(BlockDriverState *bs);
@@ -283,6 +290,117 @@ 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.bs = bs;
+
+ /* stash state before reopen */
+ raw_rs->stash_s = g_malloc0(sizeof(BDRVRawState));
+ raw_stash_state(raw_rs->stash_s, s);
+ s->fd = dup3(raw_rs->stash_s->fd, s->fd, O_CLOEXEC);
+
+ *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)) {
+ if ((flags & BDRV_O_NOCACHE)) {
+ s->open_flags |= O_DIRECT;
+ } else {
+ s->open_flags &= ~O_DIRECT;
+ }
+ ret = fcntl_setfl(s->fd, s->open_flags);
+ } else {
+
+ /* close and reopen using new flags */
+ bs->drv->bdrv_close(bs);
+ ret = bs->drv->bdrv_file_open(bs, bs->filename, flags);
Will this allow the fdset refcount to get to zero? I was hoping your
patches would prevent that from happening. Perhaps Kevin or Eric can
weigh in. qemu_open() increments the refcount for an fdset when an fd
from it is used, and qemu_close() decrements it. I think if you were
able to perform the open before the close here that refcount wouldn't
get to zero.
--
Regards,
Corey
