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authorJeff Cody <jcody@redhat.com>2012-09-20 15:13:25 -0400
committerKevin Wolf <kwolf@redhat.com>2012-09-24 15:15:12 +0200
commiteeb6b45d48800e96f67ef2a5c80332557fd45ddb (patch)
tree6923fc62d70bd600c12d9b3dd564cabcb524f738
parent3d1807ac6707773526b193f296e72c6c86969bf7 (diff)
downloadqemu-arm-eeb6b45d48800e96f67ef2a5c80332557fd45ddb.tar.gz
block: raw-posix image file reopen
This is derived from the Supriya Kannery's reopen patches. This contains the raw-posix driver changes for the bdrv_reopen_* functions. All changes are staged into a temporary scratch buffer during the prepare() stage, and copied over to the live structure during commit(). Upon abort(), all changes are abandoned, and the live structures are unmodified. The _prepare() will create an extra fd - either by means of a dup, if possible, or opening a new fd if not (for instance, access control changes). Upon _commit(), the original fd is closed and the new fd is used. Upon _abort(), the duplicate/new fd is closed. Signed-off-by: Jeff Cody <jcody@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r--block/raw-posix.c114
1 files changed, 114 insertions, 0 deletions
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 0ffb3d0e92..28d439fa81 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -138,6 +138,14 @@ typedef struct BDRVRawState {
#endif
} BDRVRawState;
+typedef struct BDRVRawReopenState {
+ int fd;
+ int open_flags;
+#ifdef CONFIG_LINUX_AIO
+ int use_aio;
+#endif
+} BDRVRawReopenState;
+
static int fd_open(BlockDriverState *bs);
static int64_t raw_getlength(BlockDriverState *bs);
@@ -290,6 +298,109 @@ static int raw_open(BlockDriverState *bs, const char *filename, int flags)
return raw_open_common(bs, filename, flags, 0);
}
+static int raw_reopen_prepare(BDRVReopenState *state,
+ BlockReopenQueue *queue, Error **errp)
+{
+ BDRVRawState *s;
+ BDRVRawReopenState *raw_s;
+ int ret = 0;
+
+ assert(state != NULL);
+ assert(state->bs != NULL);
+
+ s = state->bs->opaque;
+
+ state->opaque = g_malloc0(sizeof(BDRVRawReopenState));
+ raw_s = state->opaque;
+
+#ifdef CONFIG_LINUX_AIO
+ raw_s->use_aio = s->use_aio;
+
+ /* we can use s->aio_ctx instead of a copy, because the use_aio flag is
+ * valid in the 'false' condition even if aio_ctx is set, and raw_set_aio()
+ * won't override aio_ctx if aio_ctx is non-NULL */
+ if (raw_set_aio(&s->aio_ctx, &raw_s->use_aio, state->flags)) {
+ return -1;
+ }
+#endif
+
+ raw_parse_flags(state->flags, &raw_s->open_flags);
+
+ raw_s->fd = -1;
+
+ int fcntl_flags = O_APPEND | O_ASYNC | O_NONBLOCK;
+#ifdef O_NOATIME
+ fcntl_flags |= O_NOATIME;
+#endif
+
+ if ((raw_s->open_flags & ~fcntl_flags) == (s->open_flags & ~fcntl_flags)) {
+ /* dup the original fd */
+ /* TODO: use qemu fcntl wrapper */
+#ifdef F_DUPFD_CLOEXEC
+ raw_s->fd = fcntl(s->fd, F_DUPFD_CLOEXEC, 0);
+#else
+ raw_s->fd = dup(s->fd);
+ if (raw_s->fd != -1) {
+ qemu_set_cloexec(raw_s->fd);
+ }
+#endif
+ if (raw_s->fd >= 0) {
+ ret = fcntl_setfl(raw_s->fd, raw_s->open_flags);
+ if (ret) {
+ qemu_close(raw_s->fd);
+ raw_s->fd = -1;
+ }
+ }
+ }
+
+ /* If we cannot use fcntl, or fcntl failed, fall back to qemu_open() */
+ if (raw_s->fd == -1) {
+ assert(!(raw_s->open_flags & O_CREAT));
+ raw_s->fd = qemu_open(state->bs->filename, raw_s->open_flags);
+ if (raw_s->fd == -1) {
+ ret = -1;
+ }
+ }
+ return ret;
+}
+
+
+static void raw_reopen_commit(BDRVReopenState *state)
+{
+ BDRVRawReopenState *raw_s = state->opaque;
+ BDRVRawState *s = state->bs->opaque;
+
+ s->open_flags = raw_s->open_flags;
+
+ qemu_close(s->fd);
+ s->fd = raw_s->fd;
+#ifdef CONFIG_LINUX_AIO
+ s->use_aio = raw_s->use_aio;
+#endif
+
+ g_free(state->opaque);
+ state->opaque = NULL;
+}
+
+
+static void raw_reopen_abort(BDRVReopenState *state)
+{
+ BDRVRawReopenState *raw_s = state->opaque;
+
+ /* nothing to do if NULL, we didn't get far enough */
+ if (raw_s == NULL) {
+ return;
+ }
+
+ if (raw_s->fd >= 0) {
+ qemu_close(raw_s->fd);
+ raw_s->fd = -1;
+ }
+ g_free(state->opaque);
+ state->opaque = NULL;
+}
+
+
/* XXX: use host sector size if necessary with:
#ifdef DIOCGSECTORSIZE
{
@@ -740,6 +851,9 @@ 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,