On 6/25/22 00:49, Stefan Hajnoczi wrote: > On Fri, Jun 24, 2022 at 11:14:32AM +0800, Sam Li wrote: >> Hi Stefan, >> >> Stefan Hajnoczi <stefa...@redhat.com> 于2022年6月20日周一 15:55写道: >>> >>> On Mon, Jun 20, 2022 at 11:36:11AM +0800, Sam Li wrote: >>> >>> Hi Sam, >>> Is this version 2 of "[RFC v1] Add support for zoned device"? Please >>> keep the email subject line the same (except for "v2", "v3", etc) so >>> that it's clear which patch series this new version replaces. >>> >>>> Fix some mistakes before. It can report a range of zones now. >>> >>> This looks like the description of what changed compared to v1. Please >>> put the changelog below "---" in the future. When patch emails are >>> merged by git-am(1) it keeps the text above "---" and discards the text >>> below "---". The changelog is usually no longer useful once the patches >>> are merged, so it should be located below the "---" line. >>> >>> The text above the "---" is the commit description (an explanation of >>> why this commit is necessary). In this case the commit description >>> should explain that this patch adds .bdrv_co_zone_report() and >>> .bdrv_co_zone_mgmt() to BlockDriver so that zoned block devices can be >>> supported. >>> >>>> >>>> Signed-off-by: Sam Li <faithilike...@gmail.com> >>>> --- >>>> block/block-backend.c | 22 ++++ >>>> block/coroutines.h | 5 + >>>> block/file-posix.c | 182 ++++++++++++++++++++++++++++++ >>>> block/io.c | 23 ++++ >>>> include/block/block-common.h | 43 ++++++- >>>> include/block/block-io.h | 13 +++ >>>> include/block/block_int-common.h | 20 ++++ >>>> qemu-io-cmds.c | 118 +++++++++++++++++++ >>>> tests/qemu-iotests/tests/zoned.sh | 52 +++++++++ >>>> 9 files changed, 477 insertions(+), 1 deletion(-) >>>> create mode 100644 tests/qemu-iotests/tests/zoned.sh >>>> >>>> diff --git a/block/block-backend.c b/block/block-backend.c >>>> index e0e1aff4b1..20248e4a35 100644 >>>> --- a/block/block-backend.c >>>> +++ b/block/block-backend.c >>>> @@ -104,6 +104,8 @@ typedef struct BlockBackendAIOCB { >>>> int ret; >>>> } BlockBackendAIOCB; >>>> >>>> + >>>> + >>> >>> Please avoid whitespace changes in code that is otherwise untouched by >>> your patch. Code changes can cause merge conflicts and they make it >>> harder to use git-annotate(1), so only changes that are necessary should >>> be included in a patch. >>> >>>> static const AIOCBInfo block_backend_aiocb_info = { >>>> .get_aio_context = blk_aiocb_get_aio_context, >>>> .aiocb_size = sizeof(BlockBackendAIOCB), >>>> @@ -1810,6 +1812,25 @@ int blk_flush(BlockBackend *blk) >>>> return ret; >>>> } >>>> >>> >>> Please add a documentation comment for blk_co_zone_report() that >>> explains how to use the functions and the purpose of the arguments. For >>> example, does offset have to be the first byte in a zone or can it be >>> any byte offset? What are the alignment requirements of offset and len? >>> Why is nr_zones a pointer? >>> >>>> +int blk_co_zone_report(BlockBackend *blk, int64_t offset, int64_t len, >>> >>> Functions that run in coroutine context must be labeled with >>> coroutine_fn: >>> >>> int coroutine_fn blk_co_zone_report(...) >>> >>> This tells humans and tools that the function can only be called from a >>> coroutine. There is a blog post about coroutines in QEMU here: >>> https://blog.vmsplice.net/2014/01/coroutines-in-qemu-basics.html >>> >>>> + int64_t *nr_zones, >>>> + struct BlockZoneDescriptor *zones) >>> >>> QEMU coding style uses typedefs when defining structs, so "struct >>> BlockZoneDescriptor *zones" should be written as "BlockZoneDescriptor >>> *zones". >>> >>>> +{ >>>> + int ret; >>> >>> This function is called from the I/O code path, please mark it with: >>> >>> IO_CODE(); >>> >>> From include/block/block-io.h: >>> >>> * I/O API functions. These functions are thread-safe, and therefore >>> * can run in any thread as long as the thread has called >>> * aio_context_acquire/release(). >>> * >>> * These functions can only call functions from I/O and Common categories, >>> * but can be invoked by GS, "I/O or GS" and I/O APIs. >>> * >>> * All functions in this category must use the macro >>> * IO_CODE(); >>> * to catch when they are accidentally called by the wrong API. >>> >>>> + ret = bdrv_co_zone_report(blk->root->bs, offset, len, nr_zones, >>>> zones); >>> >>> Please add blk_inc_in_flight(blk) and blk_dec_in_flight(blk) around this >>> function call to ensure that zone report requests finish before I/O is >>> drained (see bdrv_drained_begin()). This is necessary so that it's >>> possible to wait for I/O requests, including zone report, to complete. >>> >>> Similar to blk_co_do_preadv() we need blk_wait_while_drained(blk), >>> blk_check_byte_request(), and bdrv_inc_in_flight(bs) before calling >>> bdrv_co_zone_report(). bdrv_dec_in_flight(bs) needs to be called after >>> bdrv_co_zone_report() returns. >>> >> After adding similar structure to blk_co_do_preadv(), zone operation >> command will always fail at blk_wait_while_drained(blk) because >> blk->inflight <= 0. Would it be ok to just remove >> blk_wait_while_drained? > > Are you hitting the assertion in > block/block-backend.c:blk_wait_while_drained()? > > assert(blk->in_flight > 0); > > If yes, then there is a bug in the code. You need to make sure that > blk_inc_in_flight() is called before blk_wait_while_drained(). > >>>> + BLK_ZT_CONV = BLK_ZONE_TYPE_CONVENTIONAL, >>>> + BLK_ZT_SWR = BLK_ZONE_TYPE_SEQWRITE_REQ, >>>> + BLK_ZT_SWP = BLK_ZONE_TYPE_SEQWRITE_PREF, >>>> +}; >>>> + >>>> +enum zone_cond { >>>> + BLK_ZS_NOT_WP = BLK_ZONE_COND_NOT_WP, >>>> + BLK_ZS_EMPTY = BLK_ZONE_COND_EMPTY, >>>> + BLK_ZS_IOPEN = BLK_ZONE_COND_IMP_OPEN, >>>> + BLK_ZS_EOPEN = BLK_ZONE_COND_EXP_OPEN, >>>> + BLK_ZS_CLOSED = BLK_ZONE_COND_CLOSED, >>>> + BLK_ZS_RDONLY = BLK_ZONE_COND_READONLY, >>>> + BLK_ZS_FULL = BLK_ZONE_COND_FULL, >>>> + BLK_ZS_OFFLINE = BLK_ZONE_COND_OFFLINE, >>>> +}; >>> >>> This 1:1 correspondence with Linux constants could make the code a >>> little harder to port. >>> >>> Maybe QEMU's block layer should define its own numeric constants so the >>> code doesn't rely on operating system-specific headers. >>> block/file-posix.c #ifdef __linux__ code can be responsible for >>> converting Linux-specific constants to QEMU constants (and the 1:1 >>> mapping can be used there). >>> >> Can we define those constants in block-common.h? Because >> BlockZoneDescriptor requires zone_condition, zone_type defined and >> BlockZoneDesicriptor are used in header files and qemu-io >> sub-commands. If we use #ifdef __linux__ in block-common.h, it can be >> responsible for converting Linux constants instead. >> >> Thanks for reviewing! If there is any problem, please let me know. > > I suggest defining the constants in block-common.h. #ifdef __linux__ is > not necessary in block-common.h because the constants should just be an > enum with BLK_ZS_NOT_WP = 0 and so on (no need for Linux headers). > > In block/file-posix.c you can define a helper function inside #ifdef > __linux__ that does something like: > > BlkZoneCond zone_cond_from_linux(enum blk_zone_cond val) > { > switch (val) { > case BLK_ZONE_COND_NOT_WP: > return BLK_ZS_NOT_WP; > ... > } > > The code in block/file-posix.c should call this helper to convert from > Linux values to QEMU values.
Given that the entire zone API is Linux specific (as far as I know), we do not need to have these helpers: the entire code for zones needs to be under a #ifdef __linux__. But the conversion from Linux struct blk_zone to qemu zone descriptor still needs to be done. And the perfect place to do this is the parse_zone() function. There, we can add: switch (blkz->cond) { case BLK_ZONE_COND_NOT_WP: zone->cond = BLK_ZS_NOT_WP; break; ... } And same for zone type. That will also allow checking the values returned by Linux. ZBC-2 defines more zone types and zone conditions than currently defined in /usr/include/linux/blkzoned.h. If these new zone types/conditions ever get supported by Linux, qemu can catch the values it does not support and reject the drive. > > This way the QEMU block layer does not use Linux constants and compiles > on non-Linux machines. > > Stefan -- Damien Le Moal Western Digital Research