George Melikov e24548975c OpenZFS 7745 - print error if lzc_* is called before libzfs_core_init ... The problem is that consumers of `libZFS_Core` that forget to call `libzfs_core_init()` before calling any other function of the library are having a hard time realizing their mistake. The library's internal file descriptor is declared as global static, which is ok, but it is not initialized explicitly; therefore, it defaults to 0, which is a valid file descriptor. If `libzfs_core_init()`, which explicitly initializes the correct fd, is skipped, the ioctl functions return errors that do not have anything to do with `libZFS_Core`, where the problem is actually located. Even though assertions for that existed within `libZFS_Core` for debug builds, they were never enabled because the `-DDEBUG` flag was missing from the compiler flags. This patch applies the following changes: 1. It adds `-DDEBUG` for debug builds of `libZFS_Core` and `libzfs`, to enable their assertions on debug builds. 2. It corrects an assertion within `libzfs`, where a function had been spelled incorrectly (`zpool_prop_unsupported()`) and nobody knew because the `-DDEBUG` flag was missing, and the preprocessor was taking that part of the code away. 3. The library's internal fd is initialized to `-1` and `VERIFY` assertions have been placed to check that the fd is not equal to `-1` before issuing any ioctl. It is important here to note, that the `VERIFY` assertions exist in both debug and non-debug builds. 4. In `libzfs_core_fini` we make sure to never increment the refcount of our fd below 0, and also reset the fd to `-1` when no one refers to it. The reason for this, is for the rare case that the consumer closes all references but then calls one of the library's functions without using `libzfs_core_init()` first, and in the mean time, a previous call to `open()` decided to reuse our previous fd. This scenario would have passed our assertion in non-debug builds. 5. Once the `ASSERTION` macros were enabled again, two tests from the test suite were failing in `libzfs_sendrecv.c` at a `ZIO_CHECKSUM_IS_ZERO` check within `dump_record()`. We now zero the kernel filled checksums in all `dmu_replay_record`s that we read in `cksummer()`, except the ones that are of type `DRR_BEGIN`. I considered making all assertions available for both debug and non-debug builds, but I figured that it would not be appropriate if, for example, an outside consumer of `libZFS_Core` suddenly triggers an assertion failure because they happened to call `libzfs_core_fini()`, even if previously the reference counter was `0`. Therefore, all the reference counter related assertions are only enabled for debug builds, and fd related assertions are enabled for debug and non-debug builds. Porting notes: - `ASSERT3S(g_refcount, >, 0);` added to `recv_impl` in lib/libzfs_core/libzfs_core.c . Authored by: Serapheim Dimitropoulos <serapheim@delphix.com> Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com> Reviewed by: Matthew Ahrens <mahrens@delphix.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Ported-by: George Melikov <mail@gmelikov.ru> OpenZFS-issue: https://www.illumos.org/issues/7745 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/7e3139a Closes #5698		2017-01-31 10:48:45 -08:00
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libzfs_core.c	OpenZFS 7745 - print error if lzc_* is called before libzfs_core_init	2017-01-31 10:48:45 -08:00
Makefile.am	Support parallel build trees (VPATH builds)	2015-07-17 13:42:51 -07:00