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Support removal of entire directories that contain only files

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Removing directories containing other directories is problematic from
an orphan perspective, but removing a directory only containing files
is fairly easy to do.  Add logic that checks if a directory only
contains files, and if it does, permit removal of this directory.
This commit is contained in:
Tim Nordell
2021-05-12 17:13:53 -05:00
parent 8c1931ac55
commit 5c87b6864f
1 changed files with 59 additions and 7 deletions
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66
lfs.c
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@@ -3190,9 +3190,10 @@ static int lfs_rawstat(lfs_t *lfs, const char *path, struct lfs_info *info) {
}
#ifndef LFS_READONLY
static int lfs_dir_prep_dirremoval(lfs_t *lfs, struct lfs_mlist *dir, lfs_mdir_t *newcwd, uint16_t newid)
static int lfs_dir_prep_removal(lfs_t *lfs, struct lfs_mlist *dir,
lfs_mdir_t *newcwd, uint16_t newid, lfs_block_t *pair,
lfs_gstate_t *tmp_gstate)
{
lfs_block_t pair[2];
lfs_stag_t res = lfs_dir_get(lfs, newcwd, LFS_MKTAG(0x700, 0x3ff, 0),
LFS_MKTAG(LFS_TYPE_STRUCT, newid, 8), pair);
if (res < 0) {
@@ -3206,7 +3207,46 @@ static int lfs_dir_prep_dirremoval(lfs_t *lfs, struct lfs_mlist *dir, lfs_mdir_t
}
if (dir->m.count > 0 || dir->m.split) {
return LFS_ERR_NOTEMPTY;
uint16_t id = 0;
// Walk tags stored in this directory and check for any directory
// tags. Removal of directories with a directory in them can lead
// to additional orphans in the filesystem, so we return
// LFS_ERR_NOTEMPTY in this case. Otherwise, leave the loaded
// directory for the tail end of the directory split to leave a proper
// view of the filesystem after removal.
while (true) {
if (dir->m.count == id) {
if (!dir->m.split) {
// We have iterated through the folder to the last
// tag.
break;
}
// Before we fetch the next block, update our fetched gstate xor
lfs_dir_getgstate(lfs, &dir->m, tmp_gstate);
err = lfs_dir_fetch(lfs, &dir->m, dir->m.tail);
if (err) {
return err;
}
id = 0;
}
lfs_stag_t tag = lfs_dir_get(lfs, &dir->m, LFS_MKTAG(0x780, 0x3ff, 0),
LFS_MKTAG(LFS_TYPE_NAME, id, 0), NULL);
if (tag < 0) {
return tag;
}
if (lfs_tag_type3(tag) == LFS_TYPE_DIR) {
return LFS_ERR_NOTEMPTY;
}
id += 1;
}
}
// mark fs as orphaned
@@ -3240,10 +3280,12 @@ static int lfs_rawremove(lfs_t *lfs, const char *path) {
}
struct lfs_mlist dir;
lfs_block_t pair[2];
lfs_gstate_t tmp_gstate;
dir.next = lfs->mlist;
if (lfs_tag_type3(tag) == LFS_TYPE_DIR) {
// must be empty before removal to prevent orphans
err = lfs_dir_prep_dirremoval(lfs, &dir, &cwd, lfs_tag_id(tag));
err = lfs_dir_prep_removal(lfs, &dir, &cwd, lfs_tag_id(tag), pair, &tmp_gstate);
if (err < 0) {
return err;
}
@@ -3265,11 +3307,15 @@ static int lfs_rawremove(lfs_t *lfs, const char *path) {
return err;
}
err = lfs_fs_pred(lfs, dir.m.pair, &cwd);
err = lfs_fs_pred(lfs, pair, &cwd);
if (err) {
return err;
}
// Merge in gstate from first block splits within the directory;
// lfs_dir_drop will pick up the last gstate entry.
lfs_gstate_xor(&lfs->gdelta, &tmp_gstate);
err = lfs_dir_drop(lfs, &cwd, &dir.m);
if (err) {
return err;
@@ -3309,6 +3355,8 @@ static int lfs_rawrename(lfs_t *lfs, const char *oldpath, const char *newpath) {
uint16_t newoldid = lfs_tag_id(oldtag);
struct lfs_mlist prevdir;
lfs_block_t dir_pair[2];
lfs_gstate_t tmp_gstate;
prevdir.next = lfs->mlist;
if (prevtag == LFS_ERR_NOENT) {
// check that name fits
@@ -3330,7 +3378,7 @@ static int lfs_rawrename(lfs_t *lfs, const char *oldpath, const char *newpath) {
return 0;
} else if (lfs_tag_type3(prevtag) == LFS_TYPE_DIR) {
// must be empty before removal to prevent orphans
err = lfs_dir_prep_dirremoval(lfs, &prevdir, &newcwd, newid);
err = lfs_dir_prep_removal(lfs, &prevdir, &newcwd, newid, dir_pair, &tmp_gstate);
if (err) {
return err;
}
@@ -3375,11 +3423,15 @@ static int lfs_rawrename(lfs_t *lfs, const char *oldpath, const char *newpath) {
return err;
}
err = lfs_fs_pred(lfs, prevdir.m.pair, &newcwd);
err = lfs_fs_pred(lfs, dir_pair, &newcwd);
if (err) {
return err;
}
// Merge in gstate from first split blocks in the directory;
// lfs_dir_drop will pick up the other gstate entries.
lfs_gstate_xor(&lfs->gdelta, &tmp_gstate);
err = lfs_dir_drop(lfs, &newcwd, &prevdir.m);
if (err) {
return err;