From: Hanna Reitz <hreitz@redhat.com>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: virtio-fs@redhat.com, qemu-devel@nongnu.org,
Stefan Hajnoczi <stefanha@redhat.com>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [PATCH v3 07/10] virtiofsd: Add lo_inode.fhandle
Date: Mon, 9 Aug 2021 18:41:59 +0200 [thread overview]
Message-ID: <cbf910d8-47cd-f9b1-c9ac-6e0e2036c04a@redhat.com> (raw)
In-Reply-To: <YRFH+vE30fwgGmu8@redhat.com>
On 09.08.21 17:21, Vivek Goyal wrote:
> On Fri, Jul 30, 2021 at 05:01:31PM +0200, Max Reitz wrote:
>> This new field is an alternative to lo_inode.fd: Either of the two must
>> be set. In case an O_PATH FD is needed for some lo_inode, it is either
>> taken from lo_inode.fd, if valid, or a temporary FD is opened with
>> open_by_handle_at().
>>
>> Using a file handle instead of an FD has the advantage of keeping the
>> number of open file descriptors low.
>>
>> Because open_by_handle_at() requires a mount FD (i.e. a non-O_PATH FD
>> opened on the filesystem to which the file handle refers), but every
>> lo_fhandle only has a mount ID (as returned by name_to_handle_at()), we
>> keep a hash map of such FDs in mount_fds (mapping ID to FD).
>> get_file_handle(), which is added by a later patch, will ensure that
>> every mount ID for which we have generated a handle has a corresponding
>> entry in mount_fds.
>>
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>> Reviewed-by: Connor Kuehl <ckuehl@redhat.com>
>> ---
>> tools/virtiofsd/passthrough_ll.c | 116 ++++++++++++++++++++++----
>> tools/virtiofsd/passthrough_seccomp.c | 1 +
>> 2 files changed, 102 insertions(+), 15 deletions(-)
>>
>> diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
>> index 292b7f7e27..487448d666 100644
>> --- a/tools/virtiofsd/passthrough_ll.c
>> +++ b/tools/virtiofsd/passthrough_ll.c
>> @@ -88,8 +88,25 @@ struct lo_key {
>> uint64_t mnt_id;
>> };
>>
>> +struct lo_fhandle {
>> + union {
>> + struct file_handle handle;
>> + char padding[sizeof(struct file_handle) + MAX_HANDLE_SZ];
>> + };
>> + int mount_id;
>> +};
>> +
>> +/* Maps mount IDs to an FD that we can pass to open_by_handle_at() */
>> +static GHashTable *mount_fds;
>> +pthread_rwlock_t mount_fds_lock = PTHREAD_RWLOCK_INITIALIZER;
>> +
> How about if we move this hash table inside "struct lo_data". That seems to
> be one global data structure keeping all the info. Also it can be
> cleaned up during lo_destroy().
Yes, sounds good and right, will do.
Hanna
next prev parent reply other threads:[~2021-08-09 16:42 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-30 15:01 [PATCH v3 00/10] virtiofsd: Allow using file handles instead of O_PATH FDs Max Reitz
2021-07-30 15:01 ` [PATCH v3 01/10] virtiofsd: Limit setxattr()'s creds-dropped region Max Reitz
2021-08-06 14:16 ` Vivek Goyal
2021-08-09 10:30 ` Max Reitz
2021-07-30 15:01 ` [PATCH v3 02/10] virtiofsd: Add TempFd structure Max Reitz
2021-08-06 14:41 ` Vivek Goyal
2021-08-09 10:44 ` Max Reitz
2021-07-30 15:01 ` [PATCH v3 03/10] virtiofsd: Use lo_inode_open() instead of openat() Max Reitz
2021-08-06 15:42 ` Vivek Goyal
2021-07-30 15:01 ` [PATCH v3 04/10] virtiofsd: Add lo_inode_fd() helper Max Reitz
2021-08-06 18:25 ` Vivek Goyal
2021-08-09 10:48 ` Max Reitz
2021-07-30 15:01 ` [PATCH v3 05/10] virtiofsd: Let lo_fd() return a TempFd Max Reitz
2021-07-30 15:01 ` [PATCH v3 06/10] virtiofsd: Let lo_inode_open() " Max Reitz
2021-08-06 19:55 ` Vivek Goyal
2021-08-09 13:40 ` Max Reitz
2021-07-30 15:01 ` [PATCH v3 07/10] virtiofsd: Add lo_inode.fhandle Max Reitz
2021-08-09 15:21 ` Vivek Goyal
2021-08-09 16:41 ` Hanna Reitz [this message]
2021-07-30 15:01 ` [PATCH v3 08/10] virtiofsd: Add inodes_by_handle hash table Max Reitz
2021-08-09 16:10 ` Vivek Goyal
2021-08-09 16:47 ` Hanna Reitz
2021-08-10 14:07 ` Vivek Goyal
2021-08-10 14:13 ` Hanna Reitz
2021-08-10 17:51 ` Vivek Goyal
2021-07-30 15:01 ` [PATCH v3 09/10] virtiofsd: Optionally fill lo_inode.fhandle Max Reitz
2021-08-09 18:41 ` Vivek Goyal
2021-08-10 8:32 ` Hanna Reitz
2021-08-10 15:23 ` Vivek Goyal
2021-08-10 15:26 ` Hanna Reitz
2021-08-10 15:57 ` Vivek Goyal
2021-08-11 6:41 ` Hanna Reitz
2021-08-16 19:44 ` Vivek Goyal
2021-08-17 8:27 ` Hanna Reitz
2021-08-17 19:45 ` Vivek Goyal
2021-08-18 0:14 ` Vivek Goyal
2021-08-18 13:32 ` Vivek Goyal
2021-08-18 13:48 ` Hanna Reitz
2021-08-19 16:38 ` Dr. David Alan Gilbert
2021-07-30 15:01 ` [PATCH v3 10/10] virtiofsd: Add lazy lo_do_find() Max Reitz
2021-08-09 19:08 ` Vivek Goyal
2021-08-10 8:38 ` Hanna Reitz
2021-08-10 14:12 ` Vivek Goyal
2021-08-10 14:17 ` Hanna Reitz
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