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Message-ID: <20231228014112.2836317-7-chengzhihao1@huawei.com>
Date: Thu, 28 Dec 2023 09:41:01 +0800
From: Zhihao Cheng <chengzhihao1@...wei.com>
To: <david.oberhollenzer@...ma-star.at>, <richard@....at>,
<miquel.raynal@...tlin.com>, <s.hauer@...gutronix.de>,
<Tudor.Ambarus@...aro.org>
CC: <linux-kernel@...r.kernel.org>, <linux-mtd@...ts.infradead.org>
Subject: [PATCH RFC 06/17] ubifs: repair: Extract reachable directory entries tree
This is the 6/13 step of repairing. Extract reachable directory entries
tree. Make sure that all files can be searched from '/', unreachable
file is deleted. So, all files can be accessible in userspace after
reparing.
Signed-off-by: Zhihao Cheng <chengzhihao1@...wei.com>
---
fs/ubifs/repair.c | 143 ++++++++++++++++++++++++++++++++++++++++++++++
fs/ubifs/repair.h | 4 ++
2 files changed, 147 insertions(+)
diff --git a/fs/ubifs/repair.c b/fs/ubifs/repair.c
index 5875268135ff..c9435c9aa148 100644
--- a/fs/ubifs/repair.c
+++ b/fs/ubifs/repair.c
@@ -628,6 +628,7 @@ static int update_file(struct ubifs_info *c, struct scanned_file *file,
{
struct scanned_dent_node *dent = (struct scanned_dent_node *)sn;
+ dent->file = file;
err = insert_file_dentry(file, dent);
break;
}
@@ -1315,6 +1316,144 @@ static void filter_invalid_files(struct ubifs_info *c)
}
}
+static bool dentry_is_reachable(struct ubifs_info *c,
+ struct scanned_dent_node *dent_node,
+ struct list_head *path_list)
+{
+ struct scanned_file *parent_file = NULL;
+ struct scanned_dent_node *dn, *parent_dent;
+ struct rb_node *p;
+
+ /* Dentry has already been checked as reachable. */
+ if (dent_node->can_be_found)
+ return true;
+
+ /* Check whether the path is cyclical. */
+ list_for_each_entry(dn, path_list, list) {
+ if (dn == dent_node)
+ return false;
+ }
+ dent_node->can_be_found = true;
+ list_add(&dent_node->list, path_list);
+
+ parent_file = lookup_file(c, key_inum(c, &dent_node->key));
+ /* Parent dentry is not found, unreachable. */
+ if (!parent_file)
+ return false;
+
+ /* Parent dentry is '/', reachable. */
+ if (parent_file->inum == UBIFS_ROOT_INO)
+ return true;
+
+ /*
+ * There are two situations here:
+ * 1. @file is non-xattr type. Since directory type file has only
+ * one dentry, pick first dentry from @parent_file is okay.
+ * 2. @file is xattr type. Since non-xattr files are checked in
+ * first round, so any directory entries from @parent_file must
+ * be reachable.
+ */
+ p = rb_first(&parent_file->dent_nodes);
+ if (!p)
+ return false;
+ parent_dent = rb_entry(p, struct scanned_dent_node, rb);
+
+ return dentry_is_reachable(c, parent_dent, path_list);
+}
+
+/**
+ * file_is_reachable - whether the file can be found from '/'.
+ * @c: UBIFS file-system description object
+ * @file: file object
+ *
+ * This function iterates all directory entries in given @file and checks
+ * whether each dentry is reachable. All unreachable directory entries will
+ * be removed.
+ */
+static bool file_is_reachable(struct ubifs_info *c, struct scanned_file *file)
+{
+ struct rb_node *node;
+ struct scanned_dent_node *dent_node;
+
+ if (file->inum == UBIFS_ROOT_INO)
+ return true;
+
+retry:
+ for (node = rb_first(&file->dent_nodes); node; node = rb_next(node)) {
+ LIST_HEAD(path_list);
+
+ cond_resched();
+ dent_node = rb_entry(node, struct scanned_dent_node, rb);
+
+ if (dentry_is_reachable(c, dent_node, &path_list))
+ continue;
+
+ while (!list_empty(&path_list)) {
+ cond_resched();
+ dent_node = list_entry(path_list.next,
+ struct scanned_dent_node, list);
+
+ list_del(&dent_node->list);
+ rb_erase(&dent_node->rb, &dent_node->file->dent_nodes);
+ kfree(dent_node);
+ }
+
+ /* Since dentry node is removed from rb-tree, rescan rb-tree. */
+ goto retry;
+ }
+
+ if (!rb_first(&file->dent_nodes))
+ return false;
+
+ return true;
+}
+
+/**
+ * check_dentry_tree - extract reachable directory entries.
+ * @c: UBIFS file-system description object
+ *
+ * This function iterates all directory entries and remove those
+ * unreachable ones. 'Unreachable' means that a directory entry can
+ * not be found from '/'.
+ */
+static void extract_dentry_tree(struct ubifs_info *c)
+{
+ struct rb_node *node;
+ struct scanned_file *file;
+ LIST_HEAD(unreachable);
+
+ /* Round 1: Iterate non-xattr files. */
+ for (node = rb_first(&c->repair->scanned_files); node;
+ node = rb_next(node)) {
+ cond_resched();
+ file = rb_entry(node, struct scanned_file, rb);
+
+ if (!file->ino.is_xattr && !file_is_reachable(c, file))
+ list_add(&file->list, &unreachable);
+ }
+
+ /* Round 2: Iterate xattr files. */
+ for (node = rb_first(&c->repair->scanned_files); node;
+ node = rb_next(node)) {
+ cond_resched();
+ file = rb_entry(node, struct scanned_file, rb);
+
+ if (file->ino.is_xattr && !file_is_reachable(c, file))
+ list_add(&file->list, &unreachable);
+ }
+
+ /* Remove unreachable files. */
+ while (!list_empty(&unreachable)) {
+ cond_resched();
+ file = list_entry(unreachable.next, struct scanned_file, list);
+
+ list_del(&file->list);
+ destroy_file_content(file);
+ rb_erase(&file->rb, &c->repair->scanned_files);
+ kfree(file);
+ }
+}
+
static int do_repair(struct ubifs_info *c)
{
int err = 0;
@@ -1342,6 +1481,10 @@ static int do_repair(struct ubifs_info *c)
ubifs_msg(c, "Step 5: Filter invalid files");
filter_invalid_files(c);
+ /* Step 6: Extract reachable directory entries. */
+ ubifs_msg(c, "Step 5: Extract reachable files");
+ extract_dentry_tree(c);
+
out:
destroy_scanned_info(c, &si);
return err;
diff --git a/fs/ubifs/repair.h b/fs/ubifs/repair.h
index 242bff2833bd..05bfe9a2189e 100644
--- a/fs/ubifs/repair.h
+++ b/fs/ubifs/repair.h
@@ -14,6 +14,8 @@
#ifndef __UBIFS_REPAIR_H__
#define __UBIFS_REPAIR_H__
+struct scanned_file;
+
/**
* scanned_node - common header node.
* @exist: whether the node is found by scanning
@@ -67,6 +69,7 @@ struct scanned_ino_node {
* @nlen: name length
* @name: dentry name
* @inum: target inode number
+ * @file: corresponding file
* @rb: link in the trees of:
* 1) valid dentry nodes or deleted dentry node
* 2) all scanned dentry nodes from same file
@@ -80,6 +83,7 @@ struct scanned_dent_node {
unsigned int nlen;
char name[UBIFS_MAX_NLEN];
ino_t inum;
+ struct scanned_file *file;
struct rb_node rb;
struct list_head list;
};
--
2.31.1
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