[PATCH 1/1] fsmonitor: skip sanity check if the index is split
- From
Utsav Shah via GitGitGadget <gitgitgadget@gmail.com>
- Date
- Nov 8, 2019, 07:09 UTC
- Message-ID
- <8d69ba362261690e58b3879c33ac01c8888dc473.1573196960.git.gitgitgadget@gmail.com>
- In-Reply-To
- <pull.458.git.1573196960.gitgitgadget@gmail.com>
From: Utsav Shah <utsav@dropbox.com>
The checks added in 3444ec2eb2 ("fsmonitor: don't fill bitmap with entries to be removed", 2019-10-11), to ensure that the fsmonitor_dirty bitmap does not have more bits than the index do not play well with the split index.
git update-index --fsmonitor --split-index calls write_locked_index which calls write_shared_index as well as write_split_index. The first call fills up the fsmonitor_dirty bitmap, and the second modifies the index such that istate->cache_nr is zero and this assert is hit.
The test written does reproduce the error, but only flakily. There is limited difference with GIT_TEST_FSMONITOR=fsmonitor-all or GIT_TEST_FSMONITOR=fsmonitor-watchman, so the flakiness might come from somewhere else, which I haven't tracked down.
The test also requires checkout of a new branch, and checking out back to master. It's clear that the index gets into some poor state through these operations, and there is a deeper bug somewhere.
At the very least, this patch mitigates an over-eager check for split index users while maintaining good invariants for the standard case. Also, I haven't been able to reproduce this with "standard" user commands, like status/checkout/stash, so the blast radius seems limited.
Helped-by: Kevin Willford <kewillf@microsoft.com> Helped-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Utsav Shah <utsav@dropbox.com> --- fsmonitor.c | 8 ++++---- t/t7519-status-fsmonitor.sh | 23 +++++++++++++++++++++++ 2 files changed, 27 insertions(+), 4 deletions(-)
diff --git a/fsmonitor.c b/fsmonitor.c index 1f4aa1b150..01cba22b38 100644 --- a/fsmonitor.c +++ b/fsmonitor.c @@ -16,7 +16,7 @@ static void fsmonitor_ewah_callback(size_t pos, void *is) struct index_state *istate = (struct index_state *)is; struct cache_entry *ce; - if (pos >= istate->cache_nr) + if (!istate->split_index && pos >= istate->cache_nr) BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" >= %u)", (uintmax_t)pos, istate->cache_nr); @@ -55,7 +55,7 @@ int read_fsmonitor_extension(struct index_state *istate, const void *data, } istate->fsmonitor_dirty = fsmonitor_dirty; - if (istate->fsmonitor_dirty->bit_size > istate->cache_nr) + if (!istate->split_index && istate->fsmonitor_dirty->bit_size > istate->cache_nr) BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)", (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr); @@ -83,7 +83,7 @@ void write_fsmonitor_extension(struct strbuf *sb, struct index_state *istate) uint32_t ewah_size = 0; int fixup = 0; - if (istate->fsmonitor_dirty->bit_size > istate->cache_nr) + if (!istate->split_index && istate->fsmonitor_dirty->bit_size > istate->cache_nr) BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)", (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr); @@ -252,7 +252,7 @@ void tweak_fsmonitor(struct index_state *istate) } /* Mark all previously saved entries as dirty */ - if (istate->fsmonitor_dirty->bit_size > istate->cache_nr) + if (!istate->split_index && istate->fsmonitor_dirty->bit_size > istate->cache_nr) BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)", (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr); ewah_each_bit(istate->fsmonitor_dirty, fsmonitor_ewah_callback, istate); diff --git a/t/t7519-status-fsmonitor.sh b/t/t7519-status-fsmonitor.sh index d8df990972..b5029eff3e 100755 --- a/t/t7519-status-fsmonitor.sh +++ b/t/t7519-status-fsmonitor.sh @@ -371,4 +371,27 @@ test_expect_success 'status succeeds after staging/unstaging ' ' ) ' +# Git will only split indices if we have a bunch of files created, +# so that prep work of creating a few hundred files is required. +# Note that this test doesn't fail determinstically without +# its corresponding bugfix. +test_expect_success 'update-index succeeds after staging with split index' ' + test_create_repo fsmonitor-stage-split && + ( + cd fsmonitor-stage-split && + test_commit initial && + files=$(test_seq 1 100) && + echo "hello world" > file && + touch $files && + git add -A && + git commit -m "next" && + git config core.fsmonitor "$TEST_DIRECTORY/t7519/fsmonitor-watchman" && + echo "hello world" > file && + git checkout -b new-branch && + git checkout master && + echo hello >> file && + git update-index --split-index --untracked-cache --fsmonitor + ) +' + test_done
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