forked from Imagelibrary/littlefs
94d9e097a6
The underlying issue is that lfs_fs_deorphan did not updating gstate correctly. The way it determined if there are any orphans remaining in the filesystem was by subtracting the number of found orphans from an internal counter. This internal counter is a leftover from a previous implementation that allowed leaving the lfs_fs_deorphan loop early if we know the number of expected orphans. This can happen during recursive mdir relocations, but with only a single bit in the gstate, can't happen during mount. If we detect orphans during mount, we set this internal counter to 1, assuming we will find at least one orphan. But this presents a problem, what if we find _no_ orphans? If this happens we never decrement the internal counter of orphans, so we would never clear the bit in the gstate. This leads to a running lfs_fs_deorphan on more-or-less every mutable operation in the filesystem, resulting in an extreme performance hit. The solution here is to not subtract the number of found orphans, but assume that when our lfs_fs_deorphan loop finishes, we will have no orphans, because that's the whole point of lfs_fs_deorphan. Note that the early termination of lfs_fs_deorphan was dropped because it would not actually change the runtime complexity of lfs_fs_deorphan, adds code cost, and risks fragile corner cases such as this one. --- Also added tests to assert we run lfs_fs_deorphan at most once. Found by kasper0 and Ldd309
197 lines
6.2 KiB
TOML
197 lines
6.2 KiB
TOML
[cases.test_orphans_normal]
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in = "lfs.c"
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if = 'PROG_SIZE <= 0x3fe' # only works with one crc per commit
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code = '''
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lfs_t lfs;
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lfs_format(&lfs, cfg) => 0;
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lfs_mount(&lfs, cfg) => 0;
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lfs_mkdir(&lfs, "parent") => 0;
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lfs_mkdir(&lfs, "parent/orphan") => 0;
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lfs_mkdir(&lfs, "parent/child") => 0;
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lfs_remove(&lfs, "parent/orphan") => 0;
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lfs_unmount(&lfs) => 0;
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// corrupt the child's most recent commit, this should be the update
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// to the linked-list entry, which should orphan the orphan. Note this
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// makes a lot of assumptions about the remove operation.
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lfs_mount(&lfs, cfg) => 0;
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lfs_dir_t dir;
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lfs_dir_open(&lfs, &dir, "parent/child") => 0;
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lfs_block_t block = dir.m.pair[0];
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lfs_dir_close(&lfs, &dir) => 0;
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lfs_unmount(&lfs) => 0;
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uint8_t buffer[BLOCK_SIZE];
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cfg->read(cfg, block, 0, buffer, BLOCK_SIZE) => 0;
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int off = BLOCK_SIZE-1;
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while (off >= 0 && buffer[off] == ERASE_VALUE) {
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off -= 1;
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}
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memset(&buffer[off-3], BLOCK_SIZE, 3);
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cfg->erase(cfg, block) => 0;
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cfg->prog(cfg, block, 0, buffer, BLOCK_SIZE) => 0;
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cfg->sync(cfg) => 0;
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lfs_mount(&lfs, cfg) => 0;
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struct lfs_info info;
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lfs_stat(&lfs, "parent/orphan", &info) => LFS_ERR_NOENT;
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lfs_stat(&lfs, "parent/child", &info) => 0;
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lfs_fs_size(&lfs) => 8;
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lfs_unmount(&lfs) => 0;
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lfs_mount(&lfs, cfg) => 0;
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lfs_stat(&lfs, "parent/orphan", &info) => LFS_ERR_NOENT;
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lfs_stat(&lfs, "parent/child", &info) => 0;
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lfs_fs_size(&lfs) => 8;
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// this mkdir should both create a dir and deorphan, so size
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// should be unchanged
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lfs_mkdir(&lfs, "parent/otherchild") => 0;
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lfs_stat(&lfs, "parent/orphan", &info) => LFS_ERR_NOENT;
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lfs_stat(&lfs, "parent/child", &info) => 0;
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lfs_stat(&lfs, "parent/otherchild", &info) => 0;
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lfs_fs_size(&lfs) => 8;
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lfs_unmount(&lfs) => 0;
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lfs_mount(&lfs, cfg) => 0;
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lfs_stat(&lfs, "parent/orphan", &info) => LFS_ERR_NOENT;
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lfs_stat(&lfs, "parent/child", &info) => 0;
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lfs_stat(&lfs, "parent/otherchild", &info) => 0;
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lfs_fs_size(&lfs) => 8;
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lfs_unmount(&lfs) => 0;
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'''
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# test that we only run deorphan once per power-cycle
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[cases.test_orphans_no_orphans]
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in = 'lfs.c'
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code = '''
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lfs_t lfs;
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lfs_format(&lfs, cfg) => 0;
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lfs_mount(&lfs, cfg) => 0;
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// mark the filesystem as having orphans
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lfs_fs_preporphans(&lfs, +1) => 0;
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lfs_mdir_t mdir;
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lfs_dir_fetch(&lfs, &mdir, (lfs_block_t[2]){0, 1}) => 0;
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lfs_dir_commit(&lfs, &mdir, NULL, 0) => 0;
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// we should have orphans at this state
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assert(lfs_gstate_hasorphans(&lfs.gstate));
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lfs_unmount(&lfs) => 0;
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// mount
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lfs_mount(&lfs, cfg) => 0;
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// we should detect orphans
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assert(lfs_gstate_hasorphans(&lfs.gstate));
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// force consistency
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lfs_fs_forceconsistency(&lfs) => 0;
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// we should no longer have orphans
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assert(!lfs_gstate_hasorphans(&lfs.gstate));
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lfs_unmount(&lfs) => 0;
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'''
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[cases.test_orphans_one_orphan]
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in = 'lfs.c'
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code = '''
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lfs_t lfs;
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lfs_format(&lfs, cfg) => 0;
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lfs_mount(&lfs, cfg) => 0;
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// create an orphan
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lfs_mdir_t orphan;
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lfs_alloc_ack(&lfs);
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lfs_dir_alloc(&lfs, &orphan) => 0;
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lfs_dir_commit(&lfs, &orphan, NULL, 0) => 0;
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// append our orphan and mark the filesystem as having orphans
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lfs_fs_preporphans(&lfs, +1) => 0;
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lfs_mdir_t mdir;
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lfs_dir_fetch(&lfs, &mdir, (lfs_block_t[2]){0, 1}) => 0;
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lfs_pair_tole32(orphan.pair);
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lfs_dir_commit(&lfs, &mdir, LFS_MKATTRS(
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{LFS_MKTAG(LFS_TYPE_SOFTTAIL, 0x3ff, 8), orphan.pair})) => 0;
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// we should have orphans at this state
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assert(lfs_gstate_hasorphans(&lfs.gstate));
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lfs_unmount(&lfs) => 0;
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// mount
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lfs_mount(&lfs, cfg) => 0;
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// we should detect orphans
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assert(lfs_gstate_hasorphans(&lfs.gstate));
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// force consistency
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lfs_fs_forceconsistency(&lfs) => 0;
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// we should no longer have orphans
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assert(!lfs_gstate_hasorphans(&lfs.gstate));
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lfs_unmount(&lfs) => 0;
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'''
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# reentrant testing for orphans, basically just spam mkdir/remove
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[cases.test_orphans_reentrant]
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reentrant = true
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# TODO fix this case, caused by non-DAG trees
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if = '!(DEPTH == 3 && CACHE_SIZE != 64)'
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defines = [
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{FILES=6, DEPTH=1, CYCLES=20},
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{FILES=26, DEPTH=1, CYCLES=20},
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{FILES=3, DEPTH=3, CYCLES=20},
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]
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code = '''
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lfs_t lfs;
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int err = lfs_mount(&lfs, cfg);
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if (err) {
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lfs_format(&lfs, cfg) => 0;
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lfs_mount(&lfs, cfg) => 0;
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}
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uint32_t prng = 1;
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const char alpha[] = "abcdefghijklmnopqrstuvwxyz";
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for (unsigned i = 0; i < CYCLES; i++) {
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// create random path
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char full_path[256];
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for (unsigned d = 0; d < DEPTH; d++) {
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sprintf(&full_path[2*d], "/%c", alpha[TEST_PRNG(&prng) % FILES]);
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}
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// if it does not exist, we create it, else we destroy
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struct lfs_info info;
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int res = lfs_stat(&lfs, full_path, &info);
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if (res == LFS_ERR_NOENT) {
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// create each directory in turn, ignore if dir already exists
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for (unsigned d = 0; d < DEPTH; d++) {
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char path[1024];
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strcpy(path, full_path);
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path[2*d+2] = '\0';
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err = lfs_mkdir(&lfs, path);
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assert(!err || err == LFS_ERR_EXIST);
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}
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for (unsigned d = 0; d < DEPTH; d++) {
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char path[1024];
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strcpy(path, full_path);
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path[2*d+2] = '\0';
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lfs_stat(&lfs, path, &info) => 0;
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assert(strcmp(info.name, &path[2*d+1]) == 0);
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assert(info.type == LFS_TYPE_DIR);
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}
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} else {
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// is valid dir?
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assert(strcmp(info.name, &full_path[2*(DEPTH-1)+1]) == 0);
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assert(info.type == LFS_TYPE_DIR);
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// try to delete path in reverse order, ignore if dir is not empty
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for (int d = DEPTH-1; d >= 0; d--) {
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char path[1024];
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strcpy(path, full_path);
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path[2*d+2] = '\0';
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err = lfs_remove(&lfs, path);
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assert(!err || err == LFS_ERR_NOTEMPTY);
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}
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lfs_stat(&lfs, full_path, &info) => LFS_ERR_NOENT;
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}
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}
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lfs_unmount(&lfs) => 0;
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'''
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