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[Qemu-devel] [PATCH V4 6/7] block: Create authorizations mechanism for e
From: |
Benoît Canet |
Subject: |
[Qemu-devel] [PATCH V4 6/7] block: Create authorizations mechanism for external snapshots. |
Date: |
Thu, 5 Dec 2013 18:15:02 +0100 |
Signed-off-by: Benoit Canet <address@hidden>
---
block.c | 68 +++++++++++++++++++++++++++++++++++++++++------
block/blkverify.c | 2 +-
include/block/block.h | 18 ++++++++++---
include/block/block_int.h | 12 ++++++---
4 files changed, 84 insertions(+), 16 deletions(-)
diff --git a/block.c b/block.c
index e53f24f..cb7ac88 100644
--- a/block.c
+++ b/block.c
@@ -4962,21 +4962,73 @@ int bdrv_amend_options(BlockDriverState *bs,
QEMUOptionParameter *options)
return bs->drv->bdrv_amend_options(bs, options);
}
-ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *bs)
+/* will be used to recurse on single child block filter until first format
+ * (single child block filter will store their child in bs->file)
+ */
+ExtSnapshotPerm bdrv_generic_check_ext_snapshot(BlockDriverState *bs,
+ BlockDriverState *candidate)
{
- if (bs->drv->bdrv_check_ext_snapshot) {
- return bs->drv->bdrv_check_ext_snapshot(bs);
+ if (!bs->drv) {
+ return EXT_SNAPSHOT_DO_NOT_CARE;
+ }
+
+ /* This double negation allow to implement the behavior without modifying
+ * all the BlockDrivers.
+ */
+ if (!bs->drv->authorizations[BS_CANT_SNAPSHOT]) {
+ if (bs == candidate) {
+ return EXT_SNAPSHOT_ALLOWED;
+ } else {
+ return EXT_SNAPSHOT_FORBIDDEN;
+ }
}
- if (bs->file && bs->file->drv && bs->file->drv->bdrv_check_ext_snapshot) {
- return bs->file->drv->bdrv_check_ext_snapshot(bs);
+ if (!bs->drv->authorizations[BS_FILTER_PASS_DOWN]) {
+ return EXT_SNAPSHOT_DO_NOT_CARE;
+ }
+
+ if (!bs->file) {
+ return EXT_SNAPSHOT_DO_NOT_CARE;
+ }
+
+ return bdrv_recurse_check_ext_snapshot(bs->file, candidate);
+}
+
+ExtSnapshotPerm bdrv_recurse_check_ext_snapshot(BlockDriverState *bs,
+ BlockDriverState *candidate)
+{
+ if (bs->drv && bs->drv->bdrv_recurse_check_ext_snapshot) {
+ return bs->drv->bdrv_recurse_check_ext_snapshot(bs, candidate);
}
- /* external snapshots are allowed by default */
- return EXT_SNAPSHOT_ALLOWED;
+ return bdrv_generic_check_ext_snapshot(bs, candidate);
}
-ExtSnapshotPerm bdrv_check_ext_snapshot_forbidden(BlockDriverState *bs)
+/* This function check if the candidate bs has snapshots authorized by going
+ * down the forest of bs, skipping filters and stopping on the the first bses
+ * authorizing snapshots. If one of these bses is the the candidate and has
+ * !authorizations[BS_CANT_SNAPSHOT] the snapshot is authorized.
+ */
+ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *candidate)
{
+ BlockDriverState *bs;
+
+ /* walk down the bs forest recursively */
+ QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
+ ExtSnapshotPerm perm;
+
+ if (!bs->file) {
+ continue;
+ }
+
+ perm = bdrv_recurse_check_ext_snapshot(bs->file, candidate);
+
+ /* allowed in the right subtree -> stop here */
+ if (perm == EXT_SNAPSHOT_ALLOWED) {
+ return EXT_SNAPSHOT_ALLOWED;
+ }
+ }
+
+ /* external snapshots are forbidden by default */
return EXT_SNAPSHOT_FORBIDDEN;
}
diff --git a/block/blkverify.c b/block/blkverify.c
index a7c9da2..105d4ac 100644
--- a/block/blkverify.c
+++ b/block/blkverify.c
@@ -417,7 +417,7 @@ static BlockDriver bdrv_blkverify = {
.bdrv_aio_writev = blkverify_aio_writev,
.bdrv_aio_flush = blkverify_aio_flush,
- .bdrv_check_ext_snapshot = bdrv_check_ext_snapshot_forbidden,
+ .authorizations = { true, false },
};
static void bdrv_blkverify_init(void)
diff --git a/include/block/block.h b/include/block/block.h
index 49dab83..f98f902 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -280,16 +280,26 @@ int bdrv_amend_options(BlockDriverState *bs_new,
QEMUOptionParameter *options);
/* external snapshots */
typedef enum {
- EXT_SNAPSHOT_ALLOWED,
EXT_SNAPSHOT_FORBIDDEN,
+ EXT_SNAPSHOT_DO_NOT_CARE,
+ EXT_SNAPSHOT_ALLOWED,
} ExtSnapshotPerm;
+typedef enum {
+ BS_CANT_SNAPSHOT,
+ BS_FILTER_PASS_DOWN,
+ BS_AUTHORIZATION_COUNT,
+} BsAuthorization;
+
/* return EXT_SNAPSHOT_ALLOWED if external snapshot is allowed
* return EXT_SNAPSHOT_FORBIDDEN if external snapshot is forbidden
+ * return EXT_SNAPSHOT_FORBIDDEN if the candidate bs is not in this bs tree
*/
-ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *bs);
-/* helper used to forbid external snapshots like in blkverify */
-ExtSnapshotPerm bdrv_check_ext_snapshot_forbidden(BlockDriverState *bs);
+ExtSnapshotPerm bdrv_generic_check_ext_snapshot(BlockDriverState *bs,
+ BlockDriverState *candidate);
+ExtSnapshotPerm bdrv_recurse_check_ext_snapshot(BlockDriverState *bs,
+ BlockDriverState *candidate);
+ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *candidate);
/* async block I/O */
typedef void BlockDriverDirtyHandler(BlockDriverState *bs, int64_t sector,
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 9e789d2..edd85a9 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -69,10 +69,16 @@ struct BlockDriver {
const char *format_name;
int instance_size;
- /* if not defined external snapshots are allowed
- * future block filters will query their children to build the response
+ /* this table of boolean contains authorizations for the block operations
*/
+ bool authorizations[BS_AUTHORIZATION_COUNT];
+ /* for snapshots complex block filter like Quorum can implement the
+ * following recursive callback instead of BS_CANT_SNAPSHOT.
+ * It's purpose is to recurse on the filter children while calling
+ * bdrv_recurse_check_ext_snapshot on them.
+ * For a sample implentation look in the future Quorum block filter.
*/
- ExtSnapshotPerm (*bdrv_check_ext_snapshot)(BlockDriverState *bs);
+ ExtSnapshotPerm (*bdrv_recurse_check_ext_snapshot)(BlockDriverState *bs,
+ BlockDriverState
*candidate);
int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename);
int (*bdrv_probe_device)(const char *filename);
--
1.8.3.2
- Re: [Qemu-devel] [PATCH V4 4/7] qmp: Allow to change password on names block driver states., (continued)
- Re: [Qemu-devel] [PATCH V4 4/7] qmp: Allow to change password on names block driver states., Kevin Wolf, 2013/12/10
- Re: [Qemu-devel] [PATCH V4 4/7] qmp: Allow to change password on names block driver states., Luiz Capitulino, 2013/12/10
- Re: [Qemu-devel] [PATCH V4 4/7] qmp: Allow to change password on names block driver states., Kevin Wolf, 2013/12/10
- Re: [Qemu-devel] [PATCH V4 4/7] qmp: Allow to change password on names block driver states., Luiz Capitulino, 2013/12/10
- Re: [Qemu-devel] [PATCH V4 4/7] qmp: Allow to change password on names block driver states., Kevin Wolf, 2013/12/10
- Re: [Qemu-devel] [PATCH V4 4/7] qmp: Allow to change password on names block driver states., Eric Blake, 2013/12/10
- Re: [Qemu-devel] [PATCH V4 4/7] qmp: Allow to change password on names block driver states., Fam Zheng, 2013/12/10
- Re: [Qemu-devel] [PATCH V4 4/7] qmp: Allow to change password on names block driver states., Luiz Capitulino, 2013/12/11
[Qemu-devel] [PATCH V4 6/7] block: Create authorizations mechanism for external snapshots.,
Benoît Canet <=
[Qemu-devel] [PATCH V4 7/7] qmp: Allow to take external snapshots on bs graphs node., Benoît Canet, 2013/12/05
Re: [Qemu-devel] [PATCH V4 0/7] Giving names to BlockDriverState graph nodes, Kevin Wolf, 2013/12/09