@@ -376,13 +376,21 @@ static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp)
}
}
-static void raw_parse_flags(int bdrv_flags, int *open_flags)
+static void raw_parse_flags(int bdrv_flags, int *open_flags, bool has_writers)
{
+ bool read_write = false;
assert(open_flags != NULL);
*open_flags |= O_BINARY;
*open_flags &= ~O_ACCMODE;
- if (bdrv_flags & BDRV_O_RDWR) {
+
+ if (bdrv_flags & BDRV_O_AUTO_RDONLY) {
+ read_write = has_writers;
+ } else if (bdrv_flags & BDRV_O_RDWR) {
+ read_write = true;
+ }
+
+ if (read_write) {
*open_flags |= O_RDWR;
} else {
*open_flags |= O_RDONLY;
@@ -518,24 +526,12 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
false);
s->open_flags = open_flags;
- raw_parse_flags(bdrv_flags, &s->open_flags);
+ raw_parse_flags(bdrv_flags, &s->open_flags, false);
s->fd = -1;
fd = qemu_open(filename, s->open_flags, 0644);
ret = fd < 0 ? -errno : 0;
- if (ret == -EACCES || ret == -EROFS) {
- /* Try to degrade to read-only, but if it doesn't work, still use the
- * normal error message. */
- if (bdrv_apply_auto_read_only(bs, NULL, NULL) == 0) {
- bdrv_flags &= ~BDRV_O_RDWR;
- raw_parse_flags(bdrv_flags, &s->open_flags);
- assert(!(s->open_flags & O_CREAT));
- fd = qemu_open(filename, s->open_flags);
- ret = fd < 0 ? -errno : 0;
- }
- }
-
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not open '%s'", filename);
if (ret == -EROFS) {
@@ -846,12 +842,14 @@ static int raw_handle_perm_lock(BlockDriverState *bs,
}
static int raw_reconfigure_getfd(BlockDriverState *bs, int flags,
- int *open_flags, bool force_dup,
+ int *open_flags, uint64_t perm, bool force_dup,
Error **errp)
{
BDRVRawState *s = bs->opaque;
int fd = -1;
int ret;
+ bool has_writers = perm &
+ (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED | BLK_PERM_RESIZE);
int fcntl_flags = O_APPEND | O_NONBLOCK;
#ifdef O_NOATIME
fcntl_flags |= O_NOATIME;
@@ -862,7 +860,7 @@ static int raw_reconfigure_getfd(BlockDriverState *bs, int flags,
*open_flags |= O_NONBLOCK;
}
- raw_parse_flags(flags, open_flags);
+ raw_parse_flags(flags, open_flags, has_writers);
#ifdef O_ASYNC
/* Not all operating systems have O_ASYNC, and those that don't
@@ -942,7 +940,7 @@ static int raw_reopen_prepare(BDRVReopenState *state,
qemu_opts_to_qdict(opts, state->options);
rs->fd = raw_reconfigure_getfd(state->bs, state->flags, &rs->open_flags,
- true, &local_err);
+ state->perm, true, &local_err);
if (local_err) {
error_propagate(errp, local_err);
ret = -1;
@@ -2715,7 +2713,7 @@ static int raw_check_perm(BlockDriverState *bs, uint64_t perm, uint64_t shared,
} else {
/* We may need a new fd if auto-read-only switches the mode */
assert(!s->perm_change_fd);
- ret = raw_reconfigure_getfd(bs, bs->open_flags, &open_flags,
+ ret = raw_reconfigure_getfd(bs, bs->open_flags, &open_flags, perm,
false, errp);
if (ret < 0) {
return ret;
@@ -22,12 +22,12 @@ NODE_NAME: TEST_DIR/t.IMGFMT (file, read-only)
NODE_NAME: TEST_DIR/t.IMGFMT (file, read-only)
QEMU_PROG: -drive driver=file,file=TEST_DIR/t.IMGFMT,if=none,read-only=off,auto-read-only=off: Could not open 'TEST_DIR/t.IMGFMT': Permission denied
-NODE_NAME: TEST_DIR/t.IMGFMT (file, read-only)
-NODE_NAME: TEST_DIR/t.IMGFMT (file, read-only)
+NODE_NAME: TEST_DIR/t.IMGFMT (file)
+NODE_NAME: TEST_DIR/t.IMGFMT (file)
QEMU_PROG: -drive driver=file,file=TEST_DIR/t.IMGFMT,if=none,auto-read-only=off: Could not open 'TEST_DIR/t.IMGFMT': Permission denied
-NODE_NAME: TEST_DIR/t.IMGFMT (file, read-only)
-NODE_NAME: TEST_DIR/t.IMGFMT (file, read-only)
+NODE_NAME: TEST_DIR/t.IMGFMT (file)
+NODE_NAME: TEST_DIR/t.IMGFMT (file)
=== -blockdev with read-write image: read-only/auto-read-only combinations ===
@@ -50,10 +50,10 @@ node0: TEST_DIR/t.IMGFMT (file, read-only)
node0: TEST_DIR/t.IMGFMT (file, read-only)
QEMU_PROG: -blockdev driver=file,filename=TEST_DIR/t.IMGFMT,node-name=node0,read-only=off,auto-read-only=off: Could not open 'TEST_DIR/t.IMGFMT': Permission denied
-node0: TEST_DIR/t.IMGFMT (file, read-only)
+node0: TEST_DIR/t.IMGFMT (file)
QEMU_PROG: -blockdev driver=file,filename=TEST_DIR/t.IMGFMT,node-name=node0,read-only=off: Could not open 'TEST_DIR/t.IMGFMT': Permission denied
QEMU_PROG: -blockdev driver=file,filename=TEST_DIR/t.IMGFMT,node-name=node0,auto-read-only=off: Could not open 'TEST_DIR/t.IMGFMT': Permission denied
-node0: TEST_DIR/t.IMGFMT (file, read-only)
+node0: TEST_DIR/t.IMGFMT (file)
QEMU_PROG: -blockdev driver=file,filename=TEST_DIR/t.IMGFMT,node-name=node0: Could not open 'TEST_DIR/t.IMGFMT': Permission denied
*** done
Until now, with auto-read-only=on we tried to open the file read-write first and if that failed, read-only was tried. This is actually not good enough for libvirt, which gives QEMU SELinux permissions for read-write only as soon as it actually intends to write to the image. So we need to be able to switch between read-only and read-write at runtime. This patch makes auto-read-only dynamic, i.e. the file is opened read-only as long as no user of the node has requested write permissions, but it is automatically reopened read-write as soon as the first writer is attached. Conversely, if the last writer goes away, the file is reopened read-only again. bs->read_only is no longer set for auto-read-only=on files even if the file descriptor is opened read-only because it will be transparently upgraded as soon as a writer is attached. This changes the output of qemu-iotests 232. Signed-off-by: Kevin Wolf <kwolf@redhat.com> --- block/file-posix.c | 36 +++++++++++++++++------------------- tests/qemu-iotests/232.out | 12 ++++++------ 2 files changed, 23 insertions(+), 25 deletions(-)