On 20.12.19 11:08, Stefan Hajnoczi wrote: > 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!
Good that you like it! :-) > Please send a follow-up patch that adds a qemu(1) -blockdev > 'Driver-specific options for "fuse"' documentation section. What exactly do you mean? This is not a block driver, so it doesn’t work as part of -blockdev. Currently, it can only be used through QMP (fuse-export-add/fuse-export-remove). I placed it into block/ because that just seemed like the least bad place to me (apart from creating a new top-level directory like nbd has) – and also because we already have quite some few non-driver files in block/ (io.c, the jobs (where some got drivers only rather recently), accounting.c, ...). Max
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