On 2024-02-01 10:44, Mathieu Desnoyers wrote:
On 2024-01-31 17:18, Dan Williams wrote:
[...]
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 5f1be1da92ce..11053a70f5ab 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -16,6 +16,7 @@
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include <linux/highmem.h>
+#include <linux/cleanup.h>
#include <linux/uio.h>
#include "fuse_i.h"
@@ -795,8 +796,11 @@ static void virtio_fs_cleanup_dax(void *data)
put_dax(dax_dev);
}
+DEFINE_FREE(cleanup_dax, struct dax_dev *, if (!IS_ERR_OR_NULL(_T))
virtio_fs_cleanup_dax(_T))
+
static int virtio_fs_setup_dax(struct virtio_device *vdev, struct
virtio_fs *fs)
So either I'm completely missing how ownership works in this function, or
we should be really concerned about the fact that it does no actual
cleanup of anything on any error.
[...]
Here what I'm seeing so far:
- devm_release_mem_region() is never called after
devm_request_mem_region(). Not
on error, neither on teardown,
- pgmap is never freed on error after devm_kzalloc.
I was indeed missing something: the devm_ family of functions
keeps ownership at the device level, so we would not need explicit
teardown.
{
+ struct dax_device *dax_dev __free(cleanup_dax) = NULL;
struct virtio_shm_region cache_reg;
struct dev_pagemap *pgmap;
bool have_cache;
@@ -804,6 +808,15 @@ static int virtio_fs_setup_dax(struct
virtio_device *vdev, struct virtio_fs *fs)
if (!IS_ENABLED(CONFIG_FUSE_DAX))
return 0;
+ dax_dev = alloc_dax(fs, &virtio_fs_dax_ops);
+ if (IS_ERR(dax_dev)) {
+ int rc = PTR_ERR(dax_dev);
+
+ if (rc == -EOPNOTSUPP)
+ return 0;
+ return rc;
+ }
What is gained by moving this allocation here ?
I'm still concerned about moving the call to alloc_dax() before
the setup of the memory region it will use. Are those completely
independent ?
+
/* Get cache region */
have_cache = virtio_get_shm_region(vdev, &cache_reg,
(u8)VIRTIO_FS_SHMCAP_ID_CACHE);
@@ -849,10 +862,7 @@ static int virtio_fs_setup_dax(struct
virtio_device *vdev, struct virtio_fs *fs)
dev_dbg(&vdev->dev, "%s: window kaddr 0x%px phys_addr 0x%llx len
0x%llx\n",
__func__, fs->window_kaddr, cache_reg.addr, cache_reg.len);
- fs->dax_dev = alloc_dax(fs, &virtio_fs_dax_ops);
- if (IS_ERR(fs->dax_dev))
- return PTR_ERR(fs->dax_dev);
-
+ fs->dax_dev = no_free_ptr(dax_dev);
return devm_add_action_or_reset(&vdev->dev, virtio_fs_cleanup_dax,
fs->dax_dev);
}
[...]
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
