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Message-Id: <bcf5bf66a41e73c0e8608b9cd386d8152ee2a15e.1532043059.git.theuns.verwoerd@alliedtelesis.co.nz>
Date: Fri, 20 Jul 2018 11:50:11 +1200
From: Theuns Verwoerd <theuns.verwoerd@...iedtelesis.co.nz>
To: dwmw2@...radead.org, linux-mtd@...ts.infradead.org,
linux-kernel@...r.kernel.org
Cc: Theuns Verwoerd <theuns.verwoerd@...iedtelesis.co.nz>
Subject: [PATCH 1/2] jffs2: Provide forced dirty node cleanup via POLL signal
Secure deletion under JFFS2 is complicated by the log of dirty nodes
that may contain obsoleted versions of sensitive data. There is an
existing mechanism to trigger a single gc step via -HUP signal;
extend this to trigger gc collection of all currently-dirty data via
a -POLL signal.
On receipt of -POLL, the gc will retire the current nextblock, store
the last dirty list entry, and keep continuously cycling collection
until that entry has been cleaned.
Signed-off-by: Theuns Verwoerd <theuns.verwoerd@...iedtelesis.co.nz>
---
fs/jffs2/background.c | 31 ++++++++++++++++++++++++++++++-
fs/jffs2/build.c | 1 +
fs/jffs2/jffs2_fs_sb.h | 2 ++
fs/jffs2/nodelist.h | 1 +
fs/jffs2/nodemgmt.c | 6 +++++-
5 files changed, 39 insertions(+), 2 deletions(-)
diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c
index 453a6a1fff34..4c29e2d323c4 100644
--- a/fs/jffs2/background.c
+++ b/fs/jffs2/background.c
@@ -72,15 +72,27 @@ void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
wait_for_completion(&c->gc_thread_exit);
}
+static int list_contains(struct list_head *list, struct list_head *entry)
+{
+ struct list_head *ptr;
+
+ list_for_each(ptr, list) {
+ if (ptr == entry)
+ return 1;
+ }
+ return 0;
+}
+
static int jffs2_garbage_collect_thread(void *_c)
{
struct jffs2_sb_info *c = _c;
sigset_t hupmask;
- siginitset(&hupmask, sigmask(SIGHUP));
+ siginitset(&hupmask, sigmask(SIGHUP) | sigmask(SIGPOLL));
allow_signal(SIGKILL);
allow_signal(SIGSTOP);
allow_signal(SIGHUP);
+ allow_signal(SIGPOLL);
c->gc_task = current;
complete(&c->gc_thread_start);
@@ -143,6 +155,15 @@ static int jffs2_garbage_collect_thread(void *_c)
jffs2_dbg(1, "%s(): SIGHUP received\n",
__func__);
break;
+ case SIGPOLL:
+ if (!c->tidemark) {
+ /* Force retire current half-used block */
+ if (c->nextblock)
+ jffs2_close_nextblock(c, c->nextblock);
+ /* Keep going until we hit the last element in the (now) current dirty list */
+ c->tidemark = c->dirty_list.prev;
+ }
+ break;
default:
jffs2_dbg(1, "%s(): signal %ld received\n",
__func__, signr);
@@ -156,6 +177,14 @@ static int jffs2_garbage_collect_thread(void *_c)
pr_notice("No space for garbage collection. Aborting GC thread\n");
goto die;
}
+ /* If we're working towards a tidemark, keep going until it's clean */
+ if (c->tidemark && (
+ !list_empty(&c->very_dirty_list) ||
+ list_contains(&c->dirty_list, c->tidemark) ||
+ (&c->gcblock->list) == c->tidemark))
+ goto again;
+ else if (c->tidemark)
+ c->tidemark = NULL;
}
die:
spin_lock(&c->erase_completion_lock);
diff --git a/fs/jffs2/build.c b/fs/jffs2/build.c
index b288c8ae1236..7d128705648f 100644
--- a/fs/jffs2/build.c
+++ b/fs/jffs2/build.c
@@ -405,6 +405,7 @@ int jffs2_do_mount_fs(struct jffs2_sb_info *c)
INIT_LIST_HEAD(&c->bad_used_list);
c->highest_ino = 1;
c->summary = NULL;
+ c->tidemark = NULL;
ret = jffs2_sum_init(c);
if (ret)
diff --git a/fs/jffs2/jffs2_fs_sb.h b/fs/jffs2/jffs2_fs_sb.h
index 778275f48a87..25960589e3c0 100644
--- a/fs/jffs2/jffs2_fs_sb.h
+++ b/fs/jffs2/jffs2_fs_sb.h
@@ -87,6 +87,8 @@ struct jffs2_sb_info {
uint32_t nospc_dirty_size;
+ struct list_head *tidemark; /* Last dirty block at the time a full sync started */
+
uint32_t nr_blocks;
struct jffs2_eraseblock *blocks; /* The whole array of blocks. Used for getting blocks
* from the offset (blocks[ofs / sector_size]) */
diff --git a/fs/jffs2/nodelist.h b/fs/jffs2/nodelist.h
index 0637271f3770..73348bc7f545 100644
--- a/fs/jffs2/nodelist.h
+++ b/fs/jffs2/nodelist.h
@@ -386,6 +386,7 @@ int jffs2_reserve_space(struct jffs2_sb_info *c, uint32_t minsize,
uint32_t *len, int prio, uint32_t sumsize);
int jffs2_reserve_space_gc(struct jffs2_sb_info *c, uint32_t minsize,
uint32_t *len, uint32_t sumsize);
+void jffs2_close_nextblock(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb);
struct jffs2_raw_node_ref *jffs2_add_physical_node_ref(struct jffs2_sb_info *c,
uint32_t ofs, uint32_t len,
struct jffs2_inode_cache *ic);
diff --git a/fs/jffs2/nodemgmt.c b/fs/jffs2/nodemgmt.c
index a7bbe879cfc3..c07c53f69516 100644
--- a/fs/jffs2/nodemgmt.c
+++ b/fs/jffs2/nodemgmt.c
@@ -240,7 +240,7 @@ int jffs2_reserve_space_gc(struct jffs2_sb_info *c, uint32_t minsize,
/* Classify nextblock (clean, dirty of verydirty) and force to select an other one */
-static void jffs2_close_nextblock(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb)
+void jffs2_close_nextblock(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb)
{
if (c->nextblock == NULL) {
@@ -875,6 +875,10 @@ int jffs2_thread_should_wake(struct jffs2_sb_info *c)
}
}
+ /* Pending cleanup, always wake */
+ if (c->tidemark)
+ ret = 1;
+
jffs2_dbg(1, "%s(): nr_free_blocks %d, nr_erasing_blocks %d, dirty_size 0x%x, vdirty_blocks %d: %s\n",
__func__, c->nr_free_blocks, c->nr_erasing_blocks,
c->dirty_size, nr_very_dirty, ret ? "yes" : "no");
--
2.18.0
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