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[Qemu-devel] [PATCH 3/4] virtiofsd: fix lo_destroy() resource leaks
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH 3/4] virtiofsd: fix lo_destroy() resource leaks |
Date: |
Thu, 1 Aug 2019 17:54:08 +0100 |
Now that lo_destroy() is serialized we can call unref_inode() so that
all inode resources are freed.
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
contrib/virtiofsd/passthrough_ll.c | 43 ++++++++++++++----------------
1 file changed, 20 insertions(+), 23 deletions(-)
diff --git a/contrib/virtiofsd/passthrough_ll.c
b/contrib/virtiofsd/passthrough_ll.c
index a81c01d0d1..02a5e97326 100644
--- a/contrib/virtiofsd/passthrough_ll.c
+++ b/contrib/virtiofsd/passthrough_ll.c
@@ -1340,28 +1340,6 @@ static void unref_inode(struct lo_data *lo, struct
lo_inode *inode, uint64_t n)
}
}
-static int unref_all_inodes_cb(gpointer key, gpointer value,
- gpointer user_data)
-{
- struct lo_inode *inode = value;
- struct lo_data *lo = user_data;
-
- inode->nlookup = 0;
- lo_map_remove(&lo->ino_map, inode->fuse_ino);
- close(inode->fd);
- lo_inode_put(lo, &inode); /* Drop our refcount from lo_do_lookup() */
-
- return TRUE;
-}
-
-static void unref_all_inodes(struct lo_data *lo)
-{
- pthread_mutex_lock(&lo->mutex);
- g_hash_table_foreach_remove(lo->inodes, unref_all_inodes_cb, lo);
- pthread_mutex_unlock(&lo->mutex);
-
-}
-
static void lo_forget_one(fuse_req_t req, fuse_ino_t ino, uint64_t nlookup)
{
struct lo_data *lo = lo_data(req);
@@ -2462,6 +2440,18 @@ static void lo_removemapping(fuse_req_t req, struct
fuse_session *se,
fuse_reply_err(req, ret);
}
+static int destroy_inode_cb(gpointer key, gpointer value, gpointer user_data)
+{
+ struct lo_inode *inode = value;
+ struct lo_data *lo = user_data;
+
+ /* inode->nlookup is normally protected by lo->mutex but see the
+ * comment in lo_destroy().
+ */
+ unref_inode(lo, inode, inode->nlookup);
+ return TRUE;
+}
+
static void lo_destroy(void *userdata, struct fuse_session *se)
{
struct lo_data *lo = (struct lo_data*) userdata;
@@ -2475,7 +2465,14 @@ static void lo_destroy(void *userdata, struct
fuse_session *se)
fuse_err("%s: unmap during destroy failed\n",
__func__);
}
}
- unref_all_inodes(lo);
+
+ /* Normally lo->mutex must be taken when traversing lo->inodes but
+ * lo_destroy() is a serialized request so no races are possible here.
+ *
+ * In addition, we cannot acquire lo->mutex since destroy_inode_cb()
takes it
+ * too and this would result in a recursive lock.
+ */
+ g_hash_table_foreach_remove(lo->inodes, destroy_inode_cb, lo);
}
static struct fuse_lowlevel_ops lo_oper = {
--
2.21.0