[If you have read the cover letter in x \in [v2, v5], there is nothing new here; feel free to skip to the bottom to read the changes from v4.]
There are some issues regarding filename generation right now: - You always get a JSON filename if you set even a single qcow2-specific runtime options (as long as it does not have a dot in it, which is a bug, too, but here it is working in our favor...). That is not nice and actually breaks the usage of backing files with relative filenames with such qcow2 BDS. - As hinted above, you cannot use relative backing filenames with BDS that have a JSON filename only, even though qemu might be able to obtain the directory name by walking through the BDS graph to the protocol level. - Overriding the backing file at runtime should invalidate the filename because it actually changes the BDS's data. Therefore, we need to force a JSON filename in that case, containing the backing file override. - Much of our code assumes paths never to exceed PATH_MAX in length. This is wrong, at least because of JSON filenames. This should be fixed wherever the opportunity arises. - If a driver decides to implement bdrv_refresh_filename(), that implementation has to not only refresh the filename (as one would think) but it must also refresh the runtime options (bs->full_open_options). That is stupid. (I'm allowed to say that because I'm to blame for it.) This series is enclosed by four patches (two at the front, two at the back) that fix more or less general issues. They are included because: - Patch 1 is required so that in patch 3 it's obvious why we don't need to set backing_overriden there or call bdrv_refresh_filename() - Patch 2 is already reviewed, so I might just as well keep it. - Patches 24 and 25 are basically general bug fixes. Their connection to this series is obvious, however, I think, and they depend on the rest of the series, so I decided to just put them in. Patches 3 and 4 address the third issue above, and patch 23 adds something that's missing from patch 3. It cannot be squashed into patch 3, however, because it depends on functionality introduced by patches 18 to 22. Consequently, patch 3 introduces a FIXME that is resolved by patch 23. Patches 5 to 9 address the fourth issue above, and are also necessary preparation for the following patches. Patches 10 to 16 address the second issue above, patch 17 adds a test case. They implement a bdrv_dirname() function that returns the base directory of a BDS by walking through the BDS graph to the protocol layer and then trying to obtain a path based on that BDS's exact_filename. This obviously fails if exact_filename on the protocol layer is not set. This behavior can be overriden either by any block driver along the way implementing bdrv_dirname() itself or by the user through the new 'base-directory' node option. This may allow us to resolve relative filenames even if the reference BDS only has a JSON filename. Patches 18 to 22 address both the first and last issues above. They add a field called "sgfnt_runtime_opts" to the BlockDriver structure. Block drivers may point this to an array containing all of the runtime options they accept that may change their BDS's data (i.e. that are "significant"). bdrv_refresh_filename() will use this list to generate bs->full_open_options itself (with only a little help by the block driver, if necessary, through the .bdrv_gather_child_options() function). This not only simplifies the process significantly, but also results in the default implementation generating JSON filenames only when really necessary. v6: Rebased on my block branch, and: - Patches 6, 7, 8, 15: Generally treat a NULL filename as no filename -- that means, we should usually accept NULL filenames in these filename-handling functions and not return empty filenames but NULL instead - Patch 18: Added significant options for the throttle driver git-backport-diff against v5: Key: [----] : patches are identical [####] : number of functional differences between upstream/downstream patch [down] : patch is downstream-only The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively 001/25:[----] [--] 'block/mirror: Small absolute-paths simplification' 002/25:[----] [-C] 'block: Use children list in bdrv_refresh_filename' 003/25:[----] [--] 'block: Add BDS.backing_overridden' 004/25:[----] [--] 'block: Respect backing bs in bdrv_refresh_filename' 005/25:[----] [--] 'block: Make path_combine() return the path' 006/25:[0042] [FC] 'block: bdrv_get_full_backing_filename_from_...'s ret. val.' 007/25:[0007] [FC] 'block: bdrv_get_full_backing_filename's ret. val.' 008/25:[0012] [FC] 'block: Add bdrv_make_absolute_filename()' 009/25:[----] [--] 'block: Fix bdrv_find_backing_image()' 010/25:[----] [--] 'block: Add bdrv_dirname()' 011/25:[----] [--] 'blkverify: Make bdrv_dirname() return NULL' 012/25:[----] [--] 'quorum: Make bdrv_dirname() return NULL' 013/25:[----] [--] 'block/nbd: Make bdrv_dirname() return NULL' 014/25:[----] [--] 'block/nfs: Implement bdrv_dirname()' 015/25:[0010] [FC] 'block: Use bdrv_dirname() for relative filenames' 016/25:[----] [--] 'block: Add 'base-directory' BDS option' 017/25:[----] [--] 'iotests: Add quorum case to test 110' 018/25:[0004] [FC] 'block: Add sgfnt_runtime_opts to BlockDriver' 019/25:[----] [--] 'block: Add BlockDriver.bdrv_gather_child_options' 020/25:[----] [--] 'block: Generically refresh runtime options' 021/25:[----] [-C] 'block: Purify .bdrv_refresh_filename()' 022/25:[----] [--] 'block: Do not copy exact_filename from format file' 023/25:[----] [-C] 'block: Fix FIXME from "Add BDS.backing_overridden"' 024/25:[----] [--] 'block/curl: Implement bdrv_refresh_filename()' 025/25:[----] [--] 'block/null: Generate filename even with latency-ns' Max Reitz (25): block/mirror: Small absolute-paths simplification block: Use children list in bdrv_refresh_filename block: Add BDS.backing_overridden block: Respect backing bs in bdrv_refresh_filename block: Make path_combine() return the path block: bdrv_get_full_backing_filename_from_...'s ret. val. block: bdrv_get_full_backing_filename's ret. val. block: Add bdrv_make_absolute_filename() block: Fix bdrv_find_backing_image() block: Add bdrv_dirname() blkverify: Make bdrv_dirname() return NULL quorum: Make bdrv_dirname() return NULL block/nbd: Make bdrv_dirname() return NULL block/nfs: Implement bdrv_dirname() block: Use bdrv_dirname() for relative filenames block: Add 'base-directory' BDS option iotests: Add quorum case to test 110 block: Add sgfnt_runtime_opts to BlockDriver block: Add BlockDriver.bdrv_gather_child_options block: Generically refresh runtime options block: Purify .bdrv_refresh_filename() block: Do not copy exact_filename from format file block: Fix FIXME from "Add BDS.backing_overridden" block/curl: Implement bdrv_refresh_filename() block/null: Generate filename even with latency-ns qapi/block-core.json | 9 + include/block/block.h | 15 +- include/block/block_int.h | 36 ++- block.c | 519 +++++++++++++++++++++++++++++------------- block/blkdebug.c | 58 ++--- block/blkverify.c | 29 +-- block/commit.c | 3 +- block/crypto.c | 5 + block/curl.c | 39 ++++ block/gluster.c | 19 ++ block/iscsi.c | 18 ++ block/mirror.c | 19 +- block/nbd.c | 46 ++-- block/nfs.c | 46 ++-- block/null.c | 33 ++- block/qapi.c | 12 +- block/quorum.c | 58 +++-- block/rbd.c | 5 + block/replication.c | 5 + block/sheepdog.c | 12 + block/ssh.c | 5 + block/throttle.c | 4 + block/vmdk.c | 25 +- block/vpc.c | 4 + block/vvfat.c | 4 + block/vxhs.c | 8 + blockdev.c | 16 ++ tests/qemu-iotests/051.out | 8 +- tests/qemu-iotests/051.pc.out | 8 +- tests/qemu-iotests/110 | 51 ++++- tests/qemu-iotests/110.out | 14 +- 31 files changed, 789 insertions(+), 344 deletions(-) -- 2.13.6