On Thu, Dec 19, 2019 at 03:38:00PM +0100, Max Reitz wrote: > Preamble: This series is based on a combination of my (current) block > branch and “iotests: Minor fixes”. I’ve pushed it here: > > https://git.xanclic.moe/XanClic/qemu fuse-exports-v1 > > (The base is on fuse-exports-v1-base.) > > > Hi, > > Ever since I found out that you can mount FUSE filesystems on regular > files (not just directories), I had the idea of adding FUSE block > exports to qemu where you can export block nodes as raw images. The > best thing is that you’d be able to mount an image on itself, so > whatever format it may be in, qemu lets it appear as a raw image (and > you can then use regular tools like dd on it). > > I started with some concept of a qemu-blkfuse daemon (similar to > qemu-nbd), but never sent patches, for two reasons: (1) Performance was > not good, (2) it didn’t seem right, for some reason. > > Now Kevin is proposing a storage daemon for multiple export types like > NBD, and he also mentioned FUSE (while knowing of my previous attempts). > Now it does seem right to add FUSE exports to qemu, but only in the form > of some module with a proper QAPI/QMP binding. > > Performance is still quite bad, but who cares. We can always improve > it, if the need arises. > > > This series does the following: > > First, add the FUSE export module (block/fuse.c) that implements the > basic file access functions. (Note that you need libfuse 3.8.0 or later > for SEEK_HOLE/SEEK_DATA.) > > Second, it allows using FUSE exports as a protocol in the iotests and > makes many iotests work with it. (The file node is exported by a > background qemu instance to $SOCK_DIR.) > Note that I only ran raw and qcow2 on it; I’m sure other formats > currently have some failing tests. > > This gives us a lot of coverage for, well, not free (it does take ten > patches), but for cheap; but there are still some more specialized > things we want to test, so third and last, this series adds an iotest > dedicated to FUSE exports. > > > Final rather important notice: I didn’t really run the iotests with this > yet. I wanted to, but they appear rather broken on current master, > actually. I’m not yet sure whether that’s because something in my setup > broke in the last two weeks, or because there’s quite something broken > in master (it does look like there are a couple things broken in master > currently). > > > Max Reitz (18): > configure: Detect libfuse > fuse: Allow exporting BDSs via FUSE > fuse: Implement standard FUSE operations > fuse: Add fuse-export-remove > fuse: Allow growable exports > fuse: (Partially) implement fallocate() > fuse: Implement hole detection through lseek > iotests: Do not needlessly filter _make_test_img > iotests: Do not pipe _make_test_img > iotests: Use convert -n in some cases > iotests: Avoid renaming images > iotests: Derive image names from $TEST_IMG > iotests/091: Use _cleanup_qemu instad of "wait" > iotests: Restrict some Python tests to file > iotests: Let _make_test_img guess $TEST_IMG_FILE > iotests: Allow testing FUSE exports > iotests: Enable fuse for many tests > iotests/281: Add test for FUSE exports > > block.c | 4 + > block/Makefile.objs | 3 + > block/fuse.c | 668 +++++++++++++++++++++++++++++++ > configure | 68 ++++ > include/block/fuse.h | 24 ++ > qapi/block.json | 42 ++ > tests/qemu-iotests/013 | 9 +- > tests/qemu-iotests/013.out | 3 +- > tests/qemu-iotests/018 | 5 +- > tests/qemu-iotests/018.out | 1 + > tests/qemu-iotests/020 | 2 +- > tests/qemu-iotests/025 | 2 +- > tests/qemu-iotests/026 | 2 +- > tests/qemu-iotests/028 | 16 +- > tests/qemu-iotests/028.out | 3 + > tests/qemu-iotests/031 | 2 +- > tests/qemu-iotests/034 | 2 +- > tests/qemu-iotests/036 | 2 +- > tests/qemu-iotests/037 | 2 +- > tests/qemu-iotests/038 | 2 +- > tests/qemu-iotests/039 | 2 +- > tests/qemu-iotests/046 | 7 +- > tests/qemu-iotests/046.out | 2 +- > tests/qemu-iotests/050 | 2 +- > tests/qemu-iotests/054 | 2 +- > tests/qemu-iotests/060 | 2 +- > tests/qemu-iotests/071 | 21 +- > tests/qemu-iotests/072 | 5 +- > tests/qemu-iotests/072.out | 1 + > tests/qemu-iotests/079 | 2 +- > tests/qemu-iotests/080 | 2 +- > tests/qemu-iotests/089 | 5 +- > tests/qemu-iotests/089.out | 1 + > tests/qemu-iotests/090 | 2 +- > tests/qemu-iotests/091 | 5 +- > tests/qemu-iotests/095 | 2 +- > tests/qemu-iotests/097 | 2 +- > tests/qemu-iotests/098 | 2 +- > tests/qemu-iotests/102 | 2 +- > tests/qemu-iotests/103 | 2 +- > tests/qemu-iotests/106 | 2 +- > tests/qemu-iotests/107 | 2 +- > tests/qemu-iotests/108 | 2 +- > tests/qemu-iotests/111 | 2 +- > tests/qemu-iotests/112 | 2 +- > tests/qemu-iotests/115 | 2 +- > tests/qemu-iotests/117 | 2 +- > tests/qemu-iotests/120 | 2 +- > tests/qemu-iotests/121 | 2 +- > tests/qemu-iotests/127 | 2 +- > tests/qemu-iotests/133 | 2 +- > tests/qemu-iotests/137 | 2 +- > tests/qemu-iotests/138 | 2 +- > tests/qemu-iotests/140 | 2 +- > tests/qemu-iotests/154 | 2 +- > tests/qemu-iotests/161 | 14 +- > tests/qemu-iotests/171 | 2 +- > tests/qemu-iotests/174 | 10 +- > tests/qemu-iotests/175 | 8 +- > tests/qemu-iotests/176 | 2 +- > tests/qemu-iotests/177 | 2 +- > tests/qemu-iotests/179 | 2 +- > tests/qemu-iotests/183 | 2 +- > tests/qemu-iotests/186 | 2 +- > tests/qemu-iotests/187 | 2 +- > tests/qemu-iotests/191 | 2 +- > tests/qemu-iotests/195 | 2 +- > tests/qemu-iotests/200 | 5 +- > tests/qemu-iotests/200.out | 4 +- > tests/qemu-iotests/204 | 2 +- > tests/qemu-iotests/206 | 1 + > tests/qemu-iotests/214 | 2 +- > tests/qemu-iotests/217 | 2 +- > tests/qemu-iotests/220 | 2 +- > tests/qemu-iotests/221 | 2 +- > tests/qemu-iotests/229 | 5 +- > tests/qemu-iotests/229.out | 6 +- > tests/qemu-iotests/242 | 1 + > tests/qemu-iotests/247 | 2 +- > tests/qemu-iotests/249 | 8 +- > tests/qemu-iotests/250 | 2 +- > tests/qemu-iotests/252 | 2 +- > tests/qemu-iotests/265 | 2 +- > tests/qemu-iotests/268 | 2 +- > tests/qemu-iotests/272 | 2 +- > tests/qemu-iotests/273 | 2 +- > tests/qemu-iotests/279 | 2 +- > tests/qemu-iotests/281 | 328 +++++++++++++++ > tests/qemu-iotests/281.out | 92 +++++ > tests/qemu-iotests/check | 6 + > tests/qemu-iotests/common.filter | 5 +- > tests/qemu-iotests/common.rc | 190 ++++++++- > tests/qemu-iotests/group | 1 + > 93 files changed, 1571 insertions(+), 120 deletions(-) > create mode 100644 block/fuse.c > create mode 100644 include/block/fuse.h > create mode 100755 tests/qemu-iotests/281 > create mode 100644 tests/qemu-iotests/281.out
A lot of qemu-iotests changes but the actual FUSE code is small and well worth it for the flexibility and convenience that this feature brings. Nice! Please send a follow-up patch that adds a qemu(1) -blockdev 'Driver-specific options for "fuse"' documentation section. Acked-by: Stefan Hajnoczi <stefa...@redhat.com>
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