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[Qemu-devel] [PATCH 16/41] qcow2: Return real error in qcow2_snapshot_go
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH 16/41] qcow2: Return real error in qcow2_snapshot_goto |
Date: |
Mon, 5 Dec 2011 15:20:53 +0100 |
Besides fixing the return code, this adds some comments that make clear
how the code works and that it potentially breaks images if we fail in
the wrong place. Actually fixing this is left for the next patch.
Signed-off-by: Kevin Wolf <address@hidden>
Reviewed-by: Stefan Hajnoczi <address@hidden>
---
block/qcow2-snapshot.c | 51 +++++++++++++++++++++++++++++++++++++----------
1 files changed, 40 insertions(+), 11 deletions(-)
diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index a8add9c..1ee22eb 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -386,17 +386,32 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char
*snapshot_id)
QCowSnapshot *sn;
int i, snapshot_index;
int cur_l1_bytes, sn_l1_bytes;
+ int ret;
+ /* Search the snapshot */
snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
- if (snapshot_index < 0)
+ if (snapshot_index < 0) {
return -ENOENT;
+ }
sn = &s->snapshots[snapshot_index];
- if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1)
< 0)
+ /* Decrease refcount of clusters of current L1 table.
+ * FIXME This is too early! */
+ ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
+ s->l1_size, -1);
+ if (ret < 0) {
goto fail;
+ }
- if (qcow2_grow_l1_table(bs, sn->l1_size, true) < 0)
+ /*
+ * Make sure that the current L1 table is big enough to contain the whole
+ * L1 table of the snapshot. If the snapshot L1 table is smaller, the
+ * current one must be padded with zeros.
+ */
+ ret = qcow2_grow_l1_table(bs, sn->l1_size, true);
+ if (ret < 0) {
goto fail;
+ }
cur_l1_bytes = s->l1_size * sizeof(uint64_t);
sn_l1_bytes = sn->l1_size * sizeof(uint64_t);
@@ -405,19 +420,32 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char
*snapshot_id)
memset(s->l1_table + sn->l1_size, 0, cur_l1_bytes - sn_l1_bytes);
}
- /* copy the snapshot l1 table to the current l1 table */
- if (bdrv_pread(bs->file, sn->l1_table_offset,
- s->l1_table, sn_l1_bytes) < 0)
+ /*
+ * Copy the snapshot L1 table to the current L1 table.
+ *
+ * Before overwriting the old current L1 table on disk, make sure to
+ * increase all refcounts for the clusters referenced by the new one.
+ */
+ ret = bdrv_pread(bs->file, sn->l1_table_offset, s->l1_table, sn_l1_bytes);
+ if (ret < 0) {
goto fail;
- if (bdrv_pwrite_sync(bs->file, s->l1_table_offset,
- s->l1_table, cur_l1_bytes) < 0)
+ }
+
+ ret = bdrv_pwrite_sync(bs->file, s->l1_table_offset, s->l1_table,
+ cur_l1_bytes);
+ if (ret < 0) {
goto fail;
+ }
+
for(i = 0;i < s->l1_size; i++) {
be64_to_cpus(&s->l1_table[i]);
}
- if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1)
< 0)
+ /* FIXME This is too late! */
+ ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size,
1);
+ if (ret < 0) {
goto fail;
+ }
#ifdef DEBUG_ALLOC
{
@@ -426,8 +454,9 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char
*snapshot_id)
}
#endif
return 0;
- fail:
- return -EIO;
+
+fail:
+ return ret;
}
int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
--
1.7.6.4
- [Qemu-devel] [PATCH 06/41] block: add the blockio limits command line support, (continued)
- [Qemu-devel] [PATCH 06/41] block: add the blockio limits command line support, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 02/41] qcow2: avoid reentrant bdrv_read() in copy_sectors(), Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 03/41] qed: adjust the way to get nb_sectors, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 13/41] qcow2: Update snapshot table information at once, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 15/41] qcow2: Rework qcow2_snapshot_create error handling, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 10/41] block: Add coroutine_fn marker to coroutine functions, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 09/41] hmp/qmp: add block_set_io_throttle, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 12/41] qcow2: Return real error code in qcow2_write_snapshots, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 11/41] qcow2: Return real error code in qcow2_read_snapshots, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 14/41] qcow2: Cleanups and memleak fix in qcow2_snapshot_create, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 16/41] qcow2: Return real error in qcow2_snapshot_goto,
Kevin Wolf <=
- [Qemu-devel] [PATCH 19/41] qcow2: Fix error path in qcow2_snapshot_load_tmp, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 18/41] qcow2: Fix order in qcow2_snapshot_delete, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 17/41] qcow2: Fix order of refcount updates in qcow2_snapshot_goto, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 22/41] qed: convert to .bdrv_co_is_allocated(), Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 26/41] cow: convert to .bdrv_co_is_allocated(), Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 27/41] block: drop .bdrv_is_allocated() interface, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 24/41] vvfat: convert to .bdrv_co_is_allocated(), Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 20/41] block: use public bdrv_is_allocated() interface, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 23/41] block: convert qcow2, qcow2, and vmdk to .bdrv_co_is_allocated(), Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 21/41] block: add .bdrv_co_is_allocated(), Kevin Wolf, 2011/12/05