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block: Use common write req handling in truncate

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Truncation is the last to convert from open coded req handling to
reusing helpers. This time the permission check in prepare has to adapt
to the new caller: it checks a different permission bit, and doesn't
trigger the before write notifier.

Also, truncation should always trigger a bs->total_sectors update and in
turn call parent resize_cb. Update the condition in finish helper, too.

It's intended to do a duplicated bs->read_only check before calling
bdrv_co_write_req_prepare() so that we can be more informative with the
error message, as bdrv_co_write_req_prepare() doesn't have Error
parameter.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Fam Zheng 2018-07-10 14:31:24 +08:00 committed by Kevin Wolf
parent 5416a11eb5
commit cd47d792d7
1 changed files with 36 additions and 21 deletions
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57
block/io.c
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@ -1604,14 +1604,24 @@ bdrv_co_write_req_prepare(BdrvChild *child, int64_t offset, uint64_t bytes,
is_request_serialising_and_aligned(req));
assert(req->overlap_offset <= offset);
assert(offset + bytes <= req->overlap_offset + req->overlap_bytes);
if (flags & BDRV_REQ_WRITE_UNCHANGED) {
assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE));
} else {
assert(child->perm & BLK_PERM_WRITE);
}
assert(end_sector <= bs->total_sectors || child->perm & BLK_PERM_RESIZE);
return notifier_with_return_list_notify(&bs->before_write_notifiers, req);
switch (req->type) {
case BDRV_TRACKED_WRITE:
case BDRV_TRACKED_DISCARD:
if (flags & BDRV_REQ_WRITE_UNCHANGED) {
assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE));
} else {
assert(child->perm & BLK_PERM_WRITE);
}
return notifier_with_return_list_notify(&bs->before_write_notifiers,
req);
case BDRV_TRACKED_TRUNCATE:
assert(child->perm & BLK_PERM_RESIZE);
return 0;
default:
abort();
}
}
static inline void coroutine_fn
@ -1631,8 +1641,9 @@ bdrv_co_write_req_finish(BdrvChild *child, int64_t offset, uint64_t bytes,
* beyond EOF cannot expand the image anyway.
*/
if (ret == 0 &&
end_sector > bs->total_sectors &&
req->type != BDRV_TRACKED_DISCARD) {
(req->type == BDRV_TRACKED_TRUNCATE ||
end_sector > bs->total_sectors) &&
req->type != BDRV_TRACKED_DISCARD) {
bs->total_sectors = end_sector;
bdrv_parent_cb_resize(bs);
bdrv_dirty_bitmap_truncate(bs, end_sector << BDRV_SECTOR_BITS);
@ -3111,7 +3122,6 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset,
int64_t old_size, new_bytes;
int ret;
assert(child->perm & BLK_PERM_RESIZE);
/* if bs->drv == NULL, bs is closed, so there's nothing to do here */
if (!drv) {
@ -3144,7 +3154,18 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset,
* concurrently or they might be overwritten by preallocation. */
if (new_bytes) {
mark_request_serialising(&req, 1);
wait_serialising_requests(&req);
}
if (bs->read_only) {
error_setg(errp, "Image is read-only");
ret = -EACCES;
goto out;
}
ret = bdrv_co_write_req_prepare(child, offset - new_bytes, new_bytes, &req,
0);
if (ret < 0) {
error_setg_errno(errp, -ret,
"Failed to prepare request for truncation");
goto out;
}
if (!drv->bdrv_co_truncate) {
@ -3156,13 +3177,6 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset,
ret = -ENOTSUP;
goto out;
}
if (bs->read_only) {
error_setg(errp, "Image is read-only");
ret = -EACCES;
goto out;
}
assert(!(bs->open_flags & BDRV_O_INACTIVE));
ret = drv->bdrv_co_truncate(bs, offset, prealloc, errp);
if (ret < 0) {
@ -3174,9 +3188,10 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset,
} else {
offset = bs->total_sectors * BDRV_SECTOR_SIZE;
}
bdrv_dirty_bitmap_truncate(bs, offset);
bdrv_parent_cb_resize(bs);
atomic_inc(&bs->write_gen);
/* It's possible that truncation succeeded but refresh_total_sectors
* failed, but the latter doesn't affect how we should finish the request.
* Pass 0 as the last parameter so that dirty bitmaps etc. are handled. */
bdrv_co_write_req_finish(child, offset - new_bytes, new_bytes, &req, 0);
out:
tracked_request_end(&req);