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[PULL 66/69] block: Let format drivers pass @exact
From: |
Max Reitz |
Subject: |
[PULL 66/69] block: Let format drivers pass @exact |
Date: |
Mon, 28 Oct 2019 13:14:58 +0100 |
When truncating a format node, the @exact parameter is generally handled
simply by virtue of the format storing the new size in the image
metadata. Such formats do not need to pass on the parameter to their
file nodes.
There are exceptions, though:
- raw and crypto cannot store the image size, and thus must pass on
@exact.
- When using qcow2 with an external data file, it just makes sense to
keep its size in sync with the qcow2 virtual disk (because the
external data file is the virtual disk). Therefore, we should pass
@exact when truncating it.
Signed-off-by: Max Reitz <address@hidden>
Message-id: address@hidden
Reviewed-by: Maxim Levitsky <address@hidden>
Signed-off-by: Max Reitz <address@hidden>
---
block/crypto.c | 2 +-
block/qcow2.c | 15 ++++++++++++++-
block/raw-format.c | 2 +-
3 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/block/crypto.c b/block/crypto.c
index e5a1a2cdf3..24823835c1 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -311,7 +311,7 @@ block_crypto_co_truncate(BlockDriverState *bs, int64_t
offset, bool exact,
offset += payload_offset;
- return bdrv_co_truncate(bs->file, offset, false, prealloc, errp);
+ return bdrv_co_truncate(bs->file, offset, exact, prealloc, errp);
}
static void block_crypto_close(BlockDriverState *bs)
diff --git a/block/qcow2.c b/block/qcow2.c
index de284ad803..9f32dae41f 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -4027,6 +4027,13 @@ static int coroutine_fn
qcow2_co_truncate(BlockDriverState *bs, int64_t offset,
if ((last_cluster + 1) * s->cluster_size < old_file_size) {
Error *local_err = NULL;
+ /*
+ * Do not pass @exact here: It will not help the user if
+ * we get an error here just because they wanted to shrink
+ * their qcow2 image (on a block device) with qemu-img.
+ * (And on the qcow2 layer, the @exact requirement is
+ * always fulfilled, so there is no need to pass it on.)
+ */
bdrv_co_truncate(bs->file, (last_cluster + 1) * s->cluster_size,
false, PREALLOC_MODE_OFF, &local_err);
if (local_err) {
@@ -4045,7 +4052,12 @@ static int coroutine_fn
qcow2_co_truncate(BlockDriverState *bs, int64_t offset,
switch (prealloc) {
case PREALLOC_MODE_OFF:
if (has_data_file(bs)) {
- ret = bdrv_co_truncate(s->data_file, offset, false, prealloc,
errp);
+ /*
+ * If the caller wants an exact resize, the external data
+ * file should be resized to the exact target size, too,
+ * so we pass @exact here.
+ */
+ ret = bdrv_co_truncate(s->data_file, offset, exact, prealloc,
errp);
if (ret < 0) {
goto fail;
}
@@ -4130,6 +4142,7 @@ static int coroutine_fn
qcow2_co_truncate(BlockDriverState *bs, int64_t offset,
/* Allocate the data area */
new_file_size = allocation_start +
nb_new_data_clusters * s->cluster_size;
+ /* Image file grows, so @exact does not matter */
ret = bdrv_co_truncate(bs->file, new_file_size, false, prealloc, errp);
if (ret < 0) {
error_prepend(errp, "Failed to resize underlying file: ");
diff --git a/block/raw-format.c b/block/raw-format.c
index 57d84d0bae..3a76ec7dd2 100644
--- a/block/raw-format.c
+++ b/block/raw-format.c
@@ -387,7 +387,7 @@ static int coroutine_fn raw_co_truncate(BlockDriverState
*bs, int64_t offset,
s->size = offset;
offset += s->offset;
- return bdrv_co_truncate(bs->file, offset, false, prealloc, errp);
+ return bdrv_co_truncate(bs->file, offset, exact, prealloc, errp);
}
static void raw_eject(BlockDriverState *bs, bool eject_flag)
--
2.21.0
- [PULL 54/69] qcow2: Fix broken snapshot table entries, (continued)
- [PULL 54/69] qcow2: Fix broken snapshot table entries, Max Reitz, 2019/10/28
- [PULL 49/69] qcow2: Make qcow2_write_snapshots() public, Max Reitz, 2019/10/28
- [PULL 52/69] qcow2: Separate qcow2_check_read_snapshot_table(), Max Reitz, 2019/10/28
- [PULL 57/69] qcow2: Repair snapshot table with too many entries, Max Reitz, 2019/10/28
- [PULL 58/69] qcow2: Fix v3 snapshot table entry compliancy, Max Reitz, 2019/10/28
- [PULL 61/69] block: Handle filter truncation like native impl., Max Reitz, 2019/10/28
- [PULL 55/69] qcow2: Keep track of the snapshot table length, Max Reitz, 2019/10/28
- [PULL 62/69] block/cor: Drop cor_co_truncate(), Max Reitz, 2019/10/28
- [PULL 60/69] iotests: Test qcow2's snapshot table handling, Max Reitz, 2019/10/28
- [PULL 63/69] block: Do not truncate file node when formatting, Max Reitz, 2019/10/28
- [PULL 66/69] block: Let format drivers pass @exact,
Max Reitz <=
- [PULL 67/69] block: Pass truncate exact=true where reasonable, Max Reitz, 2019/10/28
- [PULL 65/69] block: Evaluate @exact in protocol drivers, Max Reitz, 2019/10/28
- [PULL 64/69] block: Add @exact parameter to bdrv_co_truncate(), Max Reitz, 2019/10/28
- [PULL 68/69] Revert "qemu-img: Check post-truncation size", Max Reitz, 2019/10/28
- [PULL 69/69] qemu-iotests: restrict 264 to qcow2 only, Max Reitz, 2019/10/28
- Re: [PULL 00/69] Block patches for softfreeze, Peter Maydell, 2019/10/28