ext4: Handle nested ext4_journal_start/stop calls without a journal
This patch fixes a problem with handling nested calls to
ext4_journal_start/ext4_journal_stop, when there is no journal present.
Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index 139fb8c..a286598 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -161,11 +161,13 @@
handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks);
int __ext4_journal_stop(const char *where, handle_t *handle);
-#define EXT4_NOJOURNAL_HANDLE ((handle_t *) 0x1)
+#define EXT4_NOJOURNAL_MAX_REF_COUNT ((unsigned long) 4096)
+/* Note: Do not use this for NULL handles. This is only to determine if
+ * a properly allocated handle is using a journal or not. */
static inline int ext4_handle_valid(handle_t *handle)
{
- if (handle == EXT4_NOJOURNAL_HANDLE)
+ if ((unsigned long)handle < EXT4_NOJOURNAL_MAX_REF_COUNT)
return 0;
return 1;
}
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 42f81d2..7c8fe80 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2076,7 +2076,8 @@
struct ext4_iloc iloc;
int err = 0;
- if (!ext4_handle_valid(handle))
+ /* ext4_handle_valid() assumes a valid handle_t pointer */
+ if (handle && !ext4_handle_valid(handle))
return 0;
mutex_lock(&EXT4_SB(inode->i_sb)->s_orphan_lock);
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index f095c60..3f7e701 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -189,6 +189,36 @@
bg->bg_itable_unused_hi = cpu_to_le16(count >> 16);
}
+
+/* Just increment the non-pointer handle value */
+static handle_t *ext4_get_nojournal(void)
+{
+ handle_t *handle = current->journal_info;
+ unsigned long ref_cnt = (unsigned long)handle;
+
+ BUG_ON(ref_cnt >= EXT4_NOJOURNAL_MAX_REF_COUNT);
+
+ ref_cnt++;
+ handle = (handle_t *)ref_cnt;
+
+ current->journal_info = handle;
+ return handle;
+}
+
+
+/* Decrement the non-pointer handle value */
+static void ext4_put_nojournal(handle_t *handle)
+{
+ unsigned long ref_cnt = (unsigned long)handle;
+
+ BUG_ON(ref_cnt == 0);
+
+ ref_cnt--;
+ handle = (handle_t *)ref_cnt;
+
+ current->journal_info = handle;
+}
+
/*
* Wrappers for jbd2_journal_start/end.
*
@@ -215,11 +245,7 @@
}
return jbd2_journal_start(journal, nblocks);
}
- /*
- * We're not journaling, return the appropriate indication.
- */
- current->journal_info = EXT4_NOJOURNAL_HANDLE;
- return current->journal_info;
+ return ext4_get_nojournal();
}
/*
@@ -235,11 +261,7 @@
int rc;
if (!ext4_handle_valid(handle)) {
- /*
- * Do this here since we don't call jbd2_journal_stop() in
- * no-journal mode.
- */
- current->journal_info = NULL;
+ ext4_put_nojournal(handle);
return 0;
}
sb = handle->h_transaction->t_journal->j_private;