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Added support for recursive removes in directories

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"Recursion" here just refers to the ability to remove entries in a
directory while iterating over it. This is very useful when you just
want a directory gone, and can be extended to a "true" recursive remove
straightforwardly. This mainly tests that mid/rid updates in opened
mdirs are correct.

To make this work, we need to update opened dirs differently than files,
since opened dirs do not get marked as removed when its rid is removed
and contain an additional position in the dir that needs to be updated.

To keep track of the different types, littlefs now contains 2
linked-lists for opened mdirs. Maybe these should be correctly typed,
but by hiding the specific types behind an array of mdir linked-lists,
we can more efficiently iterate over both lists when necessary.

We should probably compare this approach to the type-tagged approach in
the previous littlefs implementation, but I think the idea of an array
of type-hidden linked-lists just didn't come to me then. There was also
a bit more room in the mdir structs to hide a 1-bit type field. The mdir
structs here are getting pretty squeezed since they are used everywhere.
This commit is contained in:
Christopher Haster
2023-07-20 15:22:43 -05:00
parent 0ddd851f6f
commit b1187595d6
4 changed files with 221 additions and 204 deletions
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lfs.c
+69 -49
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@@ -5079,13 +5079,15 @@ static inline lfs_size_t lfsr_mdir_weight(const lfsr_mdir_t *mdir) {
}
// track "opened" mdirs that may need to by updated
static void lfsr_mdir_addopened(lfs_t *lfs, lfsr_openedmdir_t *opened) {
opened->next = lfs->opened;
lfs->opened = opened;
static void lfsr_mdir_addopened(lfs_t *lfs,
uint8_t type, lfsr_openedmdir_t *opened) {
opened->next = lfs->opened[type];
lfs->opened[type] = opened;
}
static void lfsr_mdir_removeopened(lfs_t *lfs, lfsr_openedmdir_t *opened) {
for (lfsr_openedmdir_t **p = &lfs->opened; *p; p = &(*p)->next) {
static void lfsr_mdir_removeopened(lfs_t *lfs,
uint8_t type, lfsr_openedmdir_t *opened) {
for (lfsr_openedmdir_t **p = &lfs->opened[type]; *p; p = &(*p)->next) {
if (*p == opened) {
*p = (*p)->next;
break;
@@ -5093,8 +5095,9 @@ static void lfsr_mdir_removeopened(lfs_t *lfs, lfsr_openedmdir_t *opened) {
}
}
static bool lfsr_mdir_isopened(lfs_t *lfs, const lfsr_openedmdir_t *opened) {
for (lfsr_openedmdir_t *p = lfs->opened; p; p = p->next) {
static bool lfsr_mdir_isopened(lfs_t *lfs,
uint8_t type, const lfsr_openedmdir_t *opened) {
for (lfsr_openedmdir_t *p = lfs->opened[type]; p; p = p->next) {
if (p == opened) {
return true;
}
@@ -5669,6 +5672,7 @@ static int lfsr_mtree_split_(lfs_t *lfs, lfsr_btree_t *mtree_,
} else if (mdir_->rbyd.weight > 0) {
LFS_DEBUG("Dropping mdir 0x{%"PRIx32",%"PRIx32"}",
mdir_->rbyd.block, mdir_->redund_block);
mdir_->mid = LFSR_MID_RM;
// update our mtree
uint8_t buf[LFSR_MPTR_DSIZE];
@@ -5687,6 +5691,7 @@ static int lfsr_mtree_split_(lfs_t *lfs, lfsr_btree_t *mtree_,
} else if (msibling_->rbyd.weight > 0) {
LFS_DEBUG("Dropping mdir 0x{%"PRIx32",%"PRIx32"}",
msibling_->rbyd.block, msibling_->redund_block);
msibling_->mid = LFSR_MID_RM;
// update our mtree
uint8_t buf[LFSR_MPTR_DSIZE];
@@ -5707,6 +5712,8 @@ static int lfsr_mtree_split_(lfs_t *lfs, lfsr_btree_t *mtree_,
mdir_->rbyd.block, mdir_->redund_block);
LFS_DEBUG("Dropping mdir 0x{%"PRIx32",%"PRIx32"}",
msibling_->rbyd.block, msibling_->redund_block);
mdir_->mid = LFSR_MID_RM;
msibling_->mid = LFSR_MID_RM;
// update our mtree
err = lfsr_btree_pop(lfs, mtree_, mid);
@@ -5817,6 +5824,7 @@ static int lfsr_mdir_commit(lfs_t *lfs, lfsr_mdir_t *mdir, lfs_ssize_t *rid,
} else {
LFS_DEBUG("Dropping mdir 0x{%"PRIx32",%"PRIx32"}",
mdir_.rbyd.block, mdir_.redund_block);
mdir_.mid = LFSR_MID_RM;
// don't really need to update our mtree here
}
@@ -5856,6 +5864,7 @@ static int lfsr_mdir_commit(lfs_t *lfs, lfsr_mdir_t *mdir, lfs_ssize_t *rid,
} else if (mdir->mid != LFSR_MID_MROOT && mdir_.rbyd.weight == 0) {
LFS_DEBUG("Dropping mdir 0x{%"PRIx32",%"PRIx32"}",
mdir->rbyd.block, mdir->redund_block);
mdir_.mid = LFSR_MID_RM;
// update our mtree
err = lfsr_btree_pop(lfs, &mtree_, mdir->mid);
@@ -6116,48 +6125,58 @@ static int lfsr_mdir_commit(lfs_t *lfs, lfsr_mdir_t *mdir, lfs_ssize_t *rid,
}
// update any opened mdirs
for (lfsr_openedmdir_t *opened = lfs->opened;
opened;
opened = opened->next) {
// avoid double-updating our current mdir
if (&opened->mdir == mdir) {
continue;
}
if (opened->mdir.mid == mdir->mid) {
LFS_ASSERT(opened->rid < (lfs_ssize_t)mdir->rbyd.weight);
for (uint8_t type = 0; type < 2; type++) {
for (lfsr_openedmdir_t *opened = lfs->opened[type];
opened;
opened = opened->next) {
// avoid double-updating our current mdir
if (&opened->mdir == mdir) {
continue;
}
// first play out any attrs that change our rid
for (lfs_size_t i = 0; i < attr_count; i++) {
if (opened->rid >= attrs[i].id) {
if (opened->mdir.mid == mdir->mid
&& opened->rid >= attrs[i].id) {
LFS_ASSERT(opened->rid <= (lfs_ssize_t)mdir->rbyd.weight);
// removed?
if (opened->rid + attrs[i].delta < attrs[i].id) {
opened->rid = -2;
if (type == LFS_TYPE_REG
&& opened->rid + attrs[i].delta < attrs[i].id) {
opened->mdir.mid = LFSR_MID_RM;
} else {
opened->rid += attrs[i].delta;
}
}
// adjust dir positions if any delta changes
if (type == LFS_TYPE_DIR
&& (opened->mdir.mid > mdir->mid
|| (opened->mdir.mid == mdir->mid
&& opened->rid >= attrs[i].id))) {
((lfsr_dir_t*)opened)->pos += attrs[i].delta;
}
}
// TODO wait shouldn't this be mid?
// update mdir to follow rid
if (opened->rid == -2) {
// skip removed mdirs
} else if (opened->rid >= (lfs_ssize_t)mdir_.rbyd.weight) {
LFS_ASSERT(lfsr_btree_weight(&mtree_)
!= lfsr_mtree_weight(lfs));
opened->rid = opened->rid - mdir_.rbyd.weight;
opened->mdir = msibling_;
} else {
opened->mdir = mdir_;
// update mid if we had a split or drop
if (opened->mdir.mid == mdir->mid) {
if (opened->rid >= (lfs_ssize_t)mdir_.rbyd.weight) {
LFS_ASSERT(lfsr_btree_weight(&mtree_)
!= lfsr_mtree_weight(lfs));
opened->rid = opened->rid - mdir_.rbyd.weight;
opened->mdir = msibling_;
} else {
opened->mdir = mdir_;
// if dropped, rewind to previous mid, this is needed for
// dir read to find the next mdir correctly
if (type == LFS_TYPE_DIR && mdir_.mid == LFSR_MID_RM) {
opened->mdir.mid = mdir->mid - 1;
}
}
} else if (opened->mdir.mid > mdir->mid
&& lfsr_btree_weight(&mtree_) != lfsr_mtree_weight(lfs)) {
opened->mdir.mid += lfsr_btree_weight(&mtree_)
- lfsr_mtree_weight(lfs);
}
// update mid if we had a split or drop
} else if (opened->mdir.mid > mdir->mid
&& lfsr_btree_weight(&mtree_) != lfsr_mtree_weight(lfs)) {
opened->mdir.mid += lfsr_btree_weight(&mtree_)
- lfsr_mtree_weight(lfs);
}
}
@@ -7300,7 +7319,7 @@ int lfsr_mkdir(lfs_t *lfs, const char *path) {
// as "opened" temporarily
// TODO is this the best workaround for rid update issues?
parent.rid -= 1;
lfsr_mdir_addopened(lfs, &parent);
lfsr_mdir_addopened(lfs, LFS_TYPE_REG, &parent);
// Conveniently, we just found where our dstart should go. The dstart
// tag is an empty entry that marks our directory as being allocated.
@@ -7323,7 +7342,7 @@ int lfsr_mkdir(lfs_t *lfs, const char *path) {
goto failed_with_parent;
}
lfsr_mdir_removeopened(lfs, &parent);
lfsr_mdir_removeopened(lfs, LFS_TYPE_REG, &parent);
parent.rid += 1;
// commit our new directory into our parent, zeroing out our grm
@@ -7339,7 +7358,7 @@ int lfsr_mkdir(lfs_t *lfs, const char *path) {
return 0;
failed_with_parent:
lfsr_mdir_removeopened(lfs, &parent);
lfsr_mdir_removeopened(lfs, LFS_TYPE_REG, &parent);
return err;
}
@@ -7496,14 +7515,14 @@ int lfsr_dir_open(lfs_t *lfs, lfsr_dir_t *dir, const char *path) {
}
// add to tracked mdirs
lfsr_mdir_addopened(lfs, &dir->mdir);
dir->off = 0;
lfsr_mdir_addopened(lfs, LFS_TYPE_DIR, &dir->mdir);
dir->pos = 0;
return 0;
}
int lfsr_dir_close(lfs_t *lfs, lfsr_dir_t *dir) {
// remove from tracked mdirs
lfsr_mdir_removeopened(lfs, &dir->mdir);
lfsr_mdir_removeopened(lfs, LFS_TYPE_DIR, &dir->mdir);
return 0;
}
@@ -7539,15 +7558,15 @@ int lfsr_dir_read(lfs_t *lfs, lfsr_dir_t *dir, struct lfs_info *info) {
memset(info, 0, sizeof(struct lfs_info));
// handle "." and ".." specially
if (dir->off == 0) {
if (dir->pos == 0) {
info->type = LFS_TYPE_DIR;
strcpy(info->name, ".");
dir->off += 1;
dir->pos += 1;
return 0;
} else if (dir->off == 1) {
} else if (dir->pos == 1) {
info->type = LFS_TYPE_DIR;
strcpy(info->name, "..");
dir->off += 1;
dir->pos += 1;
return 0;
}
@@ -11131,8 +11150,9 @@ static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) {
// TODO maybe reorganize this function?
// zero opened mdir list
lfs->opened = NULL;
// zero linked-lists of opened mdirs
lfs->opened[LFS_TYPE_REG] = NULL;
lfs->opened[LFS_TYPE_DIR] = NULL;
// zero gstate
memset(lfs->grm, 0, LFSR_GRM_DSIZE);