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Refactored deduplicate/deorphan step to single deorphan step

Browse Source 
Deduplication and deorphan steps aren't required under indentical
conditions, but they can be processed in the same iteration of the
filesystem. Since lfs_alloc (requires deorphan) occurs on most write
calls to the filesystem (requires deduplication), it was simpler to
just compine the steps into a single lfs_deorphan step.

Also traded out the places where lfs_rename/lfs_remove just defer
operations to the deorphan step. This adds a bit of code, but also
significantly speeds up directory operations.
This commit is contained in:
Christopher Haster
2017-10-07 16:56:00 -05:00
parent 2936514b5e
commit 539409e2fb
2 changed files with 113 additions and 121 deletions
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233
lfs.c
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@@ -257,7 +257,6 @@ static int lfs_moved(lfs_t *lfs, const void *e);
static int lfs_relocate(lfs_t *lfs,
const lfs_block_t oldpair[2], const lfs_block_t newpair[2]);
int lfs_deorphan(lfs_t *lfs);
int lfs_deduplicate(lfs_t *lfs);
/// Block allocator ///
@@ -276,14 +275,6 @@ static int lfs_alloc_lookahead(void *p, lfs_block_t block) {
}
static int lfs_alloc(lfs_t *lfs, lfs_block_t *block) {
// deorphan if we haven't yet, only needed once after poweron
if (!lfs->deorphaned) {
int err = lfs_deorphan(lfs);
if (err) {
return err;
}
}
while (true) {
while (true) {
// check if we have looked at all blocks since last ack
@@ -440,7 +431,10 @@ struct lfs_region {
static int lfs_dir_commit(lfs_t *lfs, lfs_dir_t *dir,
const struct lfs_region *regions, int count) {
// increment revision count
dir->d.rev += 1;
// keep pairs in order such that pair[0] is most recent
lfs_pairswap(dir->pair);
for (int i = 0; i < count; i++) {
dir->d.size += regions[i].newlen - regions[i].oldlen;
@@ -629,8 +623,8 @@ static int lfs_dir_remove(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry) {
if (!(pdir.d.size & 0x80000000)) {
return lfs_dir_commit(lfs, dir, (struct lfs_region[]){
{entry->off, lfs_entry_size(entry), NULL, 0},
}, 1);
{entry->off, lfs_entry_size(entry), NULL, 0},
}, 1);
} else {
pdir.d.size &= dir->d.size | 0x7fffffff;
pdir.d.tail[0] = dir->d.tail[0];
@@ -638,9 +632,26 @@ static int lfs_dir_remove(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry) {
return lfs_dir_commit(lfs, &pdir, NULL, 0);
}
} else {
return lfs_dir_commit(lfs, dir, (struct lfs_region[]){
{entry->off, lfs_entry_size(entry), NULL, 0},
}, 1);
int err = lfs_dir_commit(lfs, dir, (struct lfs_region[]){
{entry->off, lfs_entry_size(entry), NULL, 0},
}, 1);
if (err) {
return err;
}
// shift over any files that are affected
for (lfs_file_t *f = lfs->files; f; f = f->next) {
if (lfs_paircmp(f->pair, dir->pair) == 0) {
if (f->poff == entry->off) {
f->pair[0] = 0xffffffff;
f->pair[1] = 0xffffffff;
} else if (f->poff > entry->off) {
f->poff -= lfs_entry_size(entry);
}
}
}
return 0;
}
}
@@ -776,9 +787,9 @@ static int lfs_dir_find(lfs_t *lfs, lfs_dir_t *dir,
/// Top level directory operations ///
int lfs_mkdir(lfs_t *lfs, const char *path) {
// make sure directories are clean
if (!lfs->deduplicated) {
int err = lfs_deduplicate(lfs);
// deorphan if we haven't yet, needed at most once after poweron
if (!lfs->deorphaned) {
int err = lfs_deorphan(lfs);
if (err) {
return err;
}
@@ -1149,9 +1160,9 @@ static int lfs_index_traverse(lfs_t *lfs,
/// Top level file operations ///
int lfs_file_open(lfs_t *lfs, lfs_file_t *file,
const char *path, int flags) {
// make sure directories are clean
if ((flags & 3) != LFS_O_RDONLY && !lfs->deduplicated) {
int err = lfs_deduplicate(lfs);
// deorphan if we haven't yet, needed at most once after poweron
if ((flags & 3) != LFS_O_RDONLY && !lfs->deorphaned) {
int err = lfs_deorphan(lfs);
if (err) {
return err;
}
@@ -1642,9 +1653,9 @@ int lfs_stat(lfs_t *lfs, const char *path, struct lfs_info *info) {
}
int lfs_remove(lfs_t *lfs, const char *path) {
// make sure directories are clean
if (!lfs->deduplicated) {
int err = lfs_deduplicate(lfs);
// deorphan if we haven't yet, needed at most once after poweron
if (!lfs->deorphaned) {
int err = lfs_deorphan(lfs);
if (err) {
return err;
}
@@ -1681,22 +1692,18 @@ int lfs_remove(lfs_t *lfs, const char *path) {
return err;
}
// shift over any files that are affected
for (lfs_file_t *f = lfs->files; f; f = f->next) {
if (lfs_paircmp(f->pair, cwd.pair) == 0) {
if (f->poff == entry.off) {
f->pair[0] = 0xffffffff;
f->pair[1] = 0xffffffff;
} else if (f->poff > entry.off) {
f->poff -= lfs_entry_size(&entry);
}
}
}
// if we were a directory, just run a deorphan step, this should
// collect us, although is expensive
// if we were a directory, find pred, replace tail
if (entry.d.type == LFS_TYPE_DIR) {
int err = lfs_deorphan(lfs);
int res = lfs_pred(lfs, dir.pair, &cwd);
if (res < 0) {
return res;
}
assert(res); // must have pred
cwd.d.tail[0] = dir.d.tail[0];
cwd.d.tail[1] = dir.d.tail[1];
int err = lfs_dir_commit(lfs, &cwd, NULL, 0);
if (err) {
return err;
}
@@ -1706,9 +1713,9 @@ int lfs_remove(lfs_t *lfs, const char *path) {
}
int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
// make sure directories are clean
if (!lfs->deduplicated) {
int err = lfs_deduplicate(lfs);
// deorphan if we haven't yet, needed at most once after poweron
if (!lfs->deorphaned) {
int err = lfs_deorphan(lfs);
if (err) {
return err;
}
@@ -1727,14 +1734,6 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
return err;
}
// mark as moving
oldentry.d.type |= 0x80;
err = lfs_dir_update(lfs, &oldcwd, &oldentry, NULL);
if (err) {
return err;
}
oldentry.d.type &= ~0x80;
// allocate new entry
lfs_dir_t newcwd;
err = lfs_dir_fetch(lfs, &newcwd, lfs->root);
@@ -1747,7 +1746,9 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
if (err && (err != LFS_ERR_NOENT || strchr(newpath, '/') != NULL)) {
return err;
}
bool prevexists = (err != LFS_ERR_NOENT);
bool samepair = (lfs_paircmp(oldcwd.pair, newcwd.pair) == 0);
// must have same type
if (prevexists && preventry.d.type != oldentry.d.type) {
@@ -1767,9 +1768,22 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
}
}
// mark as moving
oldentry.d.type |= 0x80;
err = lfs_dir_update(lfs, &oldcwd, &oldentry, NULL);
if (err) {
return err;
}
// update pair if newcwd == oldcwd
if (samepair) {
newcwd = oldcwd;
}
// move to new location
lfs_entry_t newentry = preventry;
newentry.d = oldentry.d;
newentry.d.type &= ~0x80;
newentry.d.nlen = strlen(newpath);
if (prevexists) {
@@ -1784,21 +1798,34 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
}
}
// if we were a directory, just run a deorphan step, this should
// collect us, although is expensive
// update pair if newcwd == oldcwd
if (samepair) {
oldcwd = newcwd;
}
// remove old entry
err = lfs_dir_remove(lfs, &oldcwd, &oldentry);
if (err) {
return err;
}
// if we were a directory, find pred, replace tail
if (prevexists && preventry.d.type == LFS_TYPE_DIR) {
int err = lfs_deorphan(lfs);
int res = lfs_pred(lfs, dir.pair, &newcwd);
if (res < 0) {
return res;
}
assert(res); // must have pred
newcwd.d.tail[0] = dir.d.tail[0];
newcwd.d.tail[1] = dir.d.tail[1];
int err = lfs_dir_commit(lfs, &newcwd, NULL, 0);
if (err) {
return err;
}
}
// just deduplicate
err = lfs_deduplicate(lfs);
if (err) {
return err;
}
return 0;
}
@@ -1847,7 +1874,6 @@ static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) {
lfs->root[1] = 0xffffffff;
lfs->files = NULL;
lfs->deorphaned = false;
lfs->deduplicated = false;
return 0;
}
@@ -1963,16 +1989,22 @@ int lfs_mount(lfs_t *lfs, const struct lfs_config *cfg) {
lfs_dir_t dir;
lfs_superblock_t superblock;
err = lfs_dir_fetch(lfs, &dir, (const lfs_block_t[2]){0, 1});
if (err && err != LFS_ERR_CORRUPT) {
return err;
}
if (!err) {
err = lfs_bd_read(lfs, dir.pair[0], sizeof(dir.d),
int err = lfs_bd_read(lfs, dir.pair[0], sizeof(dir.d),
&superblock.d, sizeof(superblock.d));
if (err) {
return err;
}
lfs->root[0] = superblock.d.root[0];
lfs->root[1] = superblock.d.root[1];
}
if (err == LFS_ERR_CORRUPT ||
memcmp(superblock.d.magic, "littlefs", 8) != 0) {
if (err || memcmp(superblock.d.magic, "littlefs", 8) != 0) {
LFS_ERROR("Invalid superblock at %d %d", dir.pair[0], dir.pair[1]);
return LFS_ERR_CORRUPT;
}
@@ -1984,7 +2016,7 @@ int lfs_mount(lfs_t *lfs, const struct lfs_config *cfg) {
return LFS_ERR_INVAL;
}
return err;
return 0;
}
int lfs_unmount(lfs_t *lfs) {
@@ -2205,7 +2237,7 @@ static int lfs_relocate(lfs_t *lfs,
if (res) {
// just replace bad pair, no desync can occur
parent.d.tail[0] = newpair[0];
parent.d.tail[0] = newpair[0];
parent.d.tail[1] = newpair[1];
return lfs_dir_commit(lfs, &parent, NULL, 0);
}
@@ -2216,27 +2248,22 @@ static int lfs_relocate(lfs_t *lfs,
int lfs_deorphan(lfs_t *lfs) {
lfs->deorphaned = true;
if (lfs_pairisnull(lfs->root)) {
return 0;
}
lfs_dir_t pdir;
lfs_dir_t cdir;
lfs_dir_t pdir = {.d.size = 0x80000000};
lfs_dir_t cwd = {.d.tail[0] = 0, .d.tail[1] = 1};
// skip superblock
int err = lfs_dir_fetch(lfs, &pdir, (const lfs_block_t[2]){0, 1});
if (err) {
return err;
}
// iterate over all directories
while (!lfs_pairisnull(pdir.d.tail)) {
int err = lfs_dir_fetch(lfs, &cdir, pdir.d.tail);
// iterate over all directory directory entries
while (!lfs_pairisnull(cwd.d.tail)) {
int err = lfs_dir_fetch(lfs, &cwd, cwd.d.tail);
if (err) {
return err;
}
// only check head blocks
// check head blocks for orphans
if (!(0x80000000 & pdir.d.size)) {
// check if we have a parent
lfs_dir_t parent;
@@ -2248,10 +2275,11 @@ int lfs_deorphan(lfs_t *lfs) {
if (!res) {
// we are an orphan
LFS_DEBUG("Orphan %d %d", pdir.d.tail[0], pdir.d.tail[1]);
LFS_DEBUG("Found orphan %d %d",
pdir.d.tail[0], pdir.d.tail[1]);
pdir.d.tail[0] = cdir.d.tail[0];
pdir.d.tail[1] = cdir.d.tail[1];
pdir.d.tail[0] = cwd.d.tail[0];
pdir.d.tail[1] = cwd.d.tail[1];
err = lfs_dir_commit(lfs, &pdir, NULL, 0);
if (err) {
@@ -2263,7 +2291,8 @@ int lfs_deorphan(lfs_t *lfs) {
if (!lfs_pairsync(entry.d.u.dir, pdir.d.tail)) {
// we have desynced
LFS_DEBUG("Desync %d %d", entry.d.u.dir[0], entry.d.u.dir[1]);
LFS_DEBUG("Found desync %d %d",
entry.d.u.dir[0], entry.d.u.dir[1]);
pdir.d.tail[0] = entry.d.u.dir[0];
pdir.d.tail[1] = entry.d.u.dir[1];
@@ -2277,34 +2306,8 @@ int lfs_deorphan(lfs_t *lfs) {
}
}
memcpy(&pdir, &cdir, sizeof(pdir));
}
return 0;
}
int lfs_deduplicate(lfs_t *lfs) {
lfs->deduplicated = true;
if (lfs_pairisnull(lfs->root)) {
return 0;
}
// skip superblock
lfs_dir_t cwd;
int err = lfs_dir_fetch(lfs, &cwd, (const lfs_block_t[2]){0, 1});
if (err) {
return err;
}
// iterate over all directory directory entries
lfs_entry_t entry;
while (!lfs_pairisnull(cwd.d.tail)) {
int err = lfs_dir_fetch(lfs, &cwd, cwd.d.tail);
if (err) {
return err;
}
// check entries for moves
lfs_entry_t entry;
while (true) {
int err = lfs_dir_next(lfs, &cwd, &entry);
if (err && err != LFS_ERR_NOENT) {
@@ -2329,18 +2332,6 @@ int lfs_deduplicate(lfs_t *lfs) {
if (err) {
return err;
}
// shift over any files that are affected
for (lfs_file_t *f = lfs->files; f; f = f->next) {
if (lfs_paircmp(f->pair, cwd.pair) == 0) {
if (f->poff == entry.off) {
f->pair[0] = 0xffffffff;
f->pair[1] = 0xffffffff;
} else if (f->poff > entry.off) {
f->poff -= lfs_entry_size(&entry);
}
}
}
} else {
LFS_DEBUG("Found partial move %d %d",
entry.d.u.dir[0], entry.d.u.dir[1]);
@@ -2352,6 +2343,8 @@ int lfs_deduplicate(lfs_t *lfs) {
}
}
}
memcpy(&pdir, &cwd, sizeof(pdir));
}
return 0;

1
lfs.h
View File

@@ -244,7 +244,6 @@ typedef struct lfs {
lfs_free_t free;
bool deorphaned;
bool deduplicated;
} lfs_t;