[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 3/4] virtiofsd: fix lo_destroy() resource leaks
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH 3/4] virtiofsd: fix lo_destroy() resource leaks |
Date: |
Mon, 5 Aug 2019 16:17:08 +0100 |
User-agent: |
Mutt/1.12.1 (2019-06-15) |
* Stefan Hajnoczi (address@hidden) wrote:
> 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>
Reviewed-by: Dr. David Alan Gilbert <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
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK