In order to fix bug 1781116, we want to override xFullPathname implementation on Unix. However, it's not currently possible to do that only for quota clients. We need to create a new VFS just for quota clients to minimize impact on other mozStorage consumers.

does it help that we don't care anymore about the telemetry part of telemetryVFS? See Bug 1065923
In practice I wonder if you want to rename it to QuotaVFS and enable it only for the connections that need it.

Bug 1447931 added some I/O activity stuff to TelemetryVFS.cpp

I see, didn't remember about that. So we could have a base VFS with that i/O activity code, and you could write your quota vfs as a wrapper around the base one, I guess. Otherwise future changes like Bug 1447931 will have to touch all the forks.

Hm, you mean that we should get rid of the telemetry stuff first ?
That sounds reasonable.

Actually, exact order probably doesn't matter. I already have a patch which removes quota stuff from TelemetryVFS. I can create a new patch which renames TelemetryVFS to IOActivityVFS and removes the telemetry stuff.

Yes, sorry. I didn't mean to tell that you should remove telemetry (unless you wish and have time of course), I was just saying how great it would be to end up with a basic vfs only having the IO metric, and the quota vfs wrapping it and only used by connections who care about it.
And that's where your patch is going towards, so I like that.

https://treeherder.mozilla.org/jobs?repo=try&revision=0bd70cb0152e40968145b44393538a17ad8dabc0

Backed out for causing build bustages on mozStorageService.cpp.

• Push with failures

• Failure log

• Backout link

[task 2023-03-07T11:58:35.050Z] 11:58:35     INFO -  gmake[4]: Entering directory '/builds/worker/workspace/obj-build/storage'
[task 2023-03-07T11:58:35.052Z] 11:58:35     INFO -  /builds/worker/fetches/sccache/sccache /builds/worker/fetches/gcc/bin/g++ --sysroot /builds/worker/fetches/sysroot-x86_64-linux-gnu -std=gnu++17 -isystem /builds/worker/fetches/sysroot-x86_64-linux-gnu/usr/include/c++/7.5.0 -isystem /builds/worker/fetches/sysroot-x86_64-linux-gnu/usr/include/x86_64-linux-gnu/c++/7.5.0 -isystem /builds/worker/fetches/sysroot-x86_64-linux-gnu/usr/include/x86_64-linux-gnu -isystem /builds/worker/fetches/sysroot-x86_64-linux-gnu/usr/include -o Unified_cpp_storage1.o -c  -I/builds/worker/workspace/obj-build/dist/stl_wrappers -I/builds/worker/workspace/obj-build/dist/system_wrappers -include /builds/worker/checkouts/gecko/config/gcc_hidden.h -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fstack-protector-strong -DDEBUG=1 -DOS_POSIX=1 -DOS_LINUX=1 -DSQLITE_MAX_LIKE_PATTERN_LENGTH=50000 -DMOZ_HAS_MOZGLUE -DMOZILLA_INTERNAL_API -DIMPL_LIBXUL -DSTATIC_EXPORTABLE_JS_API -I/builds/worker/checkouts/gecko/storage -I/builds/worker/workspace/obj-build/storage -I/builds/worker/workspace/obj-build/ipc/ipdl/_ipdlheaders -I/builds/worker/checkouts/gecko/ipc/chromium/src -I/builds/worker/checkouts/gecko/dom/base -I/builds/worker/checkouts/gecko/third_party/sqlite3/src -I/builds/worker/workspace/obj-build/dist/include -I/builds/worker/workspace/obj-build/dist/include/nspr -I/builds/worker/workspace/obj-build/dist/include/nss -DMOZILLA_CLIENT -include /builds/worker/workspace/obj-build/mozilla-config.h -D_GLIBCXX_USE_CXX11_ABI=0 -fno-sized-deallocation -fno-aligned-new -fno-exceptions -fPIC -fno-rtti -ffunction-sections -fdata-sections -fno-exceptions -fno-math-errno -pthread -pipe -gdwarf-4 -freorder-blocks -Os -fno-omit-frame-pointer -funwind-tables -Werror -Wall -Wempty-body -Wignored-qualifiers -Wpointer-arith -Wsign-compare -Wtype-limits -Wunreachable-code -Wno-invalid-offsetof -Wno-error=deprecated -Wduplicated-cond -Wimplicit-fallthrough -Wlogical-op -Wno-error=maybe-uninitialized -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wno-error=free-nonheap-object -Wformat -Wformat-overflow=2 -Wno-psabi -fno-strict-aliasing -ffp-contract=off  -MD -MP -MF .deps/Unified_cpp_storage1.o.pp   Unified_cpp_storage1.cpp
[task 2023-03-07T11:58:35.052Z] 11:58:35     INFO -  In file included from Unified_cpp_storage1.cpp:38:0:
[task 2023-03-07T11:58:35.052Z] 11:58:35    ERROR -  /builds/worker/checkouts/gecko/storage/mozStorageService.cpp:336:3: error: multi-line comment [-Werror=comment]
[task 2023-03-07T11:58:35.052Z] 11:58:35     INFO -     //                                   / \
[task 2023-03-07T11:58:35.053Z] 11:58:35     INFO -     ^
[task 2023-03-07T11:58:35.053Z] 11:58:35    ERROR -  /builds/worker/checkouts/gecko/storage/mozStorageService.cpp:342:3: error: multi-line comment [-Werror=comment]
[task 2023-03-07T11:58:35.053Z] 11:58:35     INFO -     //                          / \               / \
[task 2023-03-07T11:58:35.053Z] 11:58:35     INFO -     ^
[task 2023-03-07T11:58:35.053Z] 11:58:35     INFO -  cc1plus: all warnings being treated as errors
[task 2023-03-07T11:58:35.053Z] 11:58:35    ERROR -  gmake[4]: *** [/builds/worker/checkouts/gecko/config/rules.mk:668: Unified_cpp_storage1.o] Error 1
[task 2023-03-07T11:58:35.053Z] 11:58:35     INFO -  gmake[4]: Leaving directory '/builds/worker/workspace/obj-build/storage'

https://hg.mozilla.org/mozilla-central/rev/d166b7337e41

Landed again after fixing the multi line comment.