#include <trace/events/erofs.h>
-struct erofs_qstr {
- const unsigned char *name;
- const unsigned char *end;
-};
-
-/* based on the end of qn is accurate and it must have the trailing '\0' */
-static inline int dirnamecmp(const struct erofs_qstr *qn,
- const struct erofs_qstr *qd,
- unsigned int *matched)
+/* based on the value of qn->len is accurate */
+static inline int dirnamecmp(struct qstr *qn,
+ struct qstr *qd, unsigned int *matched)
{
- unsigned int i = *matched;
-
- /*
- * on-disk error, let's only BUG_ON in the debugging mode.
- * otherwise, it will return 1 to just skip the invalid name
- * and go on (in consideration of the lookup performance).
- */
- DBG_BUGON(qd->name > qd->end);
-
- /* qd could not have trailing '\0' */
- /* However it is absolutely safe if < qd->end */
- while (qd->name + i < qd->end && qd->name[i] != '\0') {
- if (qn->name[i] != qd->name[i]) {
- *matched = i;
- return qn->name[i] > qd->name[i] ? 1 : -1;
+ unsigned int i = *matched, len = min(qn->len, qd->len);
+loop:
+ if (unlikely(i >= len)) {
+ *matched = i;
+ if (qn->len < qd->len) {
+ /*
+ * actually (qn->len == qd->len)
+ * when qd->name[i] == '\0'
+ */
+ return qd->name[i] == '\0' ? 0 : -1;
}
- ++i;
+ return (qn->len > qd->len);
+ }
+
+ if (qn->name[i] != qd->name[i]) {
+ *matched = i;
+ return qn->name[i] > qd->name[i] ? 1 : -1;
}
- *matched = i;
- /* See comments in __d_alloc on the terminating NUL character */
- return qn->name[i] == '\0' ? 0 : 1;
-}
-#define nameoff_from_disk(off, sz) (le16_to_cpu(off) & ((sz) - 1))
+ ++i;
+ goto loop;
+}
-static struct erofs_dirent *find_target_dirent(struct erofs_qstr *name,
- u8 *data,
- unsigned int dirblksize,
- const int ndirents)
+static struct erofs_dirent *find_target_dirent(
+ struct qstr *name,
+ u8 *data, int maxsize)
{
- int head, back;
+ unsigned int ndirents, head, back;
unsigned int startprfx, endprfx;
struct erofs_dirent *const de = (struct erofs_dirent *)data;
+ /* make sure that maxsize is valid */
+ BUG_ON(maxsize < sizeof(struct erofs_dirent));
+
+ ndirents = le16_to_cpu(de->nameoff) / sizeof(*de);
+
+ /* corrupted dir (may be unnecessary...) */
+ BUG_ON(!ndirents);
+
head = 0;
back = ndirents - 1;
startprfx = endprfx = 0;
while (head <= back) {
- const int mid = head + (back - head) / 2;
- const int nameoff = nameoff_from_disk(de[mid].nameoff,
- dirblksize);
+ unsigned int mid = head + (back - head) / 2;
+ unsigned int nameoff = le16_to_cpu(de[mid].nameoff);
unsigned int matched = min(startprfx, endprfx);
- struct erofs_qstr dname = {
- .name = data + nameoff,
- .end = unlikely(mid >= ndirents - 1) ?
- data + dirblksize :
- data + nameoff_from_disk(de[mid + 1].nameoff,
- dirblksize)
- };
+
+ struct qstr dname = QSTR_INIT(data + nameoff,
+ unlikely(mid >= ndirents - 1) ?
+ maxsize - nameoff :
+ le16_to_cpu(de[mid + 1].nameoff) - nameoff);
/* string comparison without already matched prefix */
int ret = dirnamecmp(name, &dname, &matched);
- if (unlikely(!ret)) {
+ if (unlikely(!ret))
return de + mid;
- } else if (ret > 0) {
+ else if (ret > 0) {
head = mid + 1;
startprfx = matched;
- } else {
+ } else if (unlikely(mid < 1)) /* fix "mid" overflow */
+ break;
+ else {
back = mid - 1;
endprfx = matched;
}
return ERR_PTR(-ENOENT);
}
-static struct page *find_target_block_classic(struct inode *dir,
- struct erofs_qstr *name,
- int *_diff,
- int *_ndirents)
+static struct page *find_target_block_classic(
+ struct inode *dir,
+ struct qstr *name, int *_diff)
{
unsigned int startprfx, endprfx;
- int head, back;
+ unsigned int head, back;
struct address_space *const mapping = dir->i_mapping;
struct page *candidate = ERR_PTR(-ENOENT);
back = inode_datablocks(dir) - 1;
while (head <= back) {
- const int mid = head + (back - head) / 2;
+ unsigned int mid = head + (back - head) / 2;
struct page *page = read_mapping_page(mapping, mid, NULL);
- if (!IS_ERR(page)) {
- struct erofs_dirent *de = kmap_atomic(page);
- const int nameoff = nameoff_from_disk(de->nameoff,
- EROFS_BLKSIZ);
- const int ndirents = nameoff / sizeof(*de);
+ if (IS_ERR(page)) {
+exact_out:
+ if (!IS_ERR(candidate)) /* valid candidate */
+ put_page(candidate);
+ return page;
+ } else {
int diff;
- unsigned int matched;
- struct erofs_qstr dname;
+ unsigned int ndirents, matched;
+ struct qstr dname;
+ struct erofs_dirent *de = kmap_atomic(page);
+ unsigned int nameoff = le16_to_cpu(de->nameoff);
- if (unlikely(!ndirents)) {
- DBG_BUGON(1);
- put_page(page);
- page = ERR_PTR(-EIO);
- goto out;
- }
+ ndirents = nameoff / sizeof(*de);
+
+ /* corrupted dir (should have one entry at least) */
+ BUG_ON(!ndirents || nameoff > PAGE_SIZE);
matched = min(startprfx, endprfx);
dname.name = (u8 *)de + nameoff;
- if (ndirents == 1)
- dname.end = (u8 *)de + EROFS_BLKSIZ;
- else
- dname.end = (u8 *)de +
- nameoff_from_disk(de[1].nameoff,
- EROFS_BLKSIZ);
+ dname.len = ndirents == 1 ?
+ /* since the rest of the last page is 0 */
+ EROFS_BLKSIZ - nameoff
+ : le16_to_cpu(de[1].nameoff) - nameoff;
/* string comparison without already matched prefix */
diff = dirnamecmp(name, &dname, &matched);
if (unlikely(!diff)) {
*_diff = 0;
- goto out;
+ goto exact_out;
} else if (diff > 0) {
head = mid + 1;
startprfx = matched;
if (likely(!IS_ERR(candidate)))
put_page(candidate);
candidate = page;
- *_ndirents = ndirents;
} else {
put_page(page);
+ if (unlikely(mid < 1)) /* fix "mid" overflow */
+ break;
+
back = mid - 1;
endprfx = matched;
}
- continue;
}
-out: /* free if the candidate is valid */
- if (!IS_ERR(candidate))
- put_page(candidate);
- return page;
}
*_diff = 1;
return candidate;
}
int erofs_namei(struct inode *dir,
- struct qstr *name,
- erofs_nid_t *nid, unsigned int *d_type)
+ struct qstr *name,
+ erofs_nid_t *nid, unsigned int *d_type)
{
- int diff, ndirents;
+ int diff;
struct page *page;
u8 *data;
struct erofs_dirent *de;
- struct erofs_qstr qn;
if (unlikely(!dir->i_size))
return -ENOENT;
- qn.name = name->name;
- qn.end = name->name + name->len;
-
diff = 1;
- page = find_target_block_classic(dir, &qn, &diff, &ndirents);
+ page = find_target_block_classic(dir, name, &diff);
if (unlikely(IS_ERR(page)))
return PTR_ERR(page);
/* the target page has been mapped */
de = likely(diff) ?
/* since the rest of the last page is 0 */
- find_target_dirent(&qn, data, EROFS_BLKSIZ, ndirents) :
+ find_target_dirent(name, data, EROFS_BLKSIZ) :
(struct erofs_dirent *)data;
if (likely(!IS_ERR(de))) {
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