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Switched back to simple deorphan-step on directory remove

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Originally I tried to reuse the indirect delete to accomplish truely
atomic directory removes, however this fell apart when it came to
implementing directory removes as a side-effect of renames.

A single indirect-delete simply can't handle renames with removes as
a side effects. When copying an entry to its destination, we need to
atomically delete both the old entry, and the source of our copy. We
can't delete both with only a single indirect-delete. It is possible to
accomplish this with two indirect-deletes, but this is such an uncommon
case that it's really not worth supporting efficiently due to how
expensive globals are.

I also dropped indirect-deletes for normal directory removes. I may add
it back later, but at the moment it's extra code cost for that's not
traveled very often.

As a result, restructured the indirect delete handling to be a bit more
generic, now with a multipurpose lfs_globals_t struct instead of the
delete specific lfs_entry_t struct.

Also worked on integrating xored-globals, now with several primitive
global operations to manage fetching/updating globals on disk.
This commit is contained in:
Christopher Haster
2018-07-01 22:29:42 -05:00
parent 3ffcedb95b
commit cebf7aa0fe
3 changed files with 323 additions and 96 deletions
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tests/test_move.sh
+29 -3
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@@ -59,7 +59,7 @@ tests/test.py << TEST
lfs_rename(&lfs, "b/hello", "c/hello") => 0;
lfs_unmount(&lfs) => 0;
TEST
truncate -s-7 blocks/6
truncate -s-11 blocks/6
tests/test.py << TEST
lfs_mount(&lfs, &cfg) => 0;
lfs_dir_open(&lfs, &dir[0], "b") => 0;
@@ -86,8 +86,8 @@ tests/test.py << TEST
lfs_rename(&lfs, "c/hello", "d/hello") => 0;
lfs_unmount(&lfs) => 0;
TEST
truncate -s-7 blocks/8
truncate -s-7 blocks/a
truncate -s-11 blocks/8
truncate -s-11 blocks/a
tests/test.py << TEST
lfs_mount(&lfs, &cfg) => 0;
lfs_dir_open(&lfs, &dir[0], "c") => 0;
@@ -108,6 +108,32 @@ tests/test.py << TEST
lfs_unmount(&lfs) => 0;
TEST
echo "--- Move file after corrupt ---"
tests/test.py -s << TEST
lfs_mount(&lfs, &cfg) => 0;
lfs_rename(&lfs, "c/hello", "d/hello") => 0;
lfs_unmount(&lfs) => 0;
TEST
tests/test.py << TEST
lfs_mount(&lfs, &cfg) => 0;
lfs_dir_open(&lfs, &dir[0], "c") => 0;
lfs_dir_read(&lfs, &dir[0], &info) => 1;
strcmp(info.name, ".") => 0;
lfs_dir_read(&lfs, &dir[0], &info) => 1;
strcmp(info.name, "..") => 0;
lfs_dir_read(&lfs, &dir[0], &info) => 0;
lfs_dir_close(&lfs, &dir[0]) => 0;
lfs_dir_open(&lfs, &dir[0], "d") => 0;
lfs_dir_read(&lfs, &dir[0], &info) => 1;
strcmp(info.name, ".") => 0;
lfs_dir_read(&lfs, &dir[0], &info) => 1;
strcmp(info.name, "..") => 0;
lfs_dir_read(&lfs, &dir[0], &info) => 1;
strcmp(info.name, "hello") => 0;
lfs_dir_read(&lfs, &dir[0], &info) => 0;
lfs_unmount(&lfs) => 0;
TEST
echo "--- Move dir ---"
tests/test.py << TEST
lfs_mount(&lfs, &cfg) => 0;