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Re: [Qemu-devel] Re: [V9fs-developer] [PATCH] virtio-9p: getattr server
From: |
Sripathi Kodi |
Subject: |
Re: [Qemu-devel] Re: [V9fs-developer] [PATCH] virtio-9p: getattr server implementation for 9P2000.L protocol. |
Date: |
Thu, 1 Jul 2010 14:26:13 +0530 |
On Thu, 01 Jul 2010 11:01:15 +0530
"Aneesh Kumar K. V" <address@hidden> wrote:
> On Fri, 28 May 2010 16:08:43 +0530, Sripathi Kodi <address@hidden> wrote:
> > From: M. Mohan Kumar <address@hidden>
> >
> > SYNOPSIS
> >
> > size[4] Tgetattr tag[2] fid[4]
> >
> > size[4] Rgetattr tag[2] lstat[n]
> >
> > DESCRIPTION
> >
> > The getattr transaction inquires about the file identified by fid.
> > The reply will contain a machine-independent directory entry,
> > laid out as follows:
> >
> > qid.type[1]
> > the type of the file (directory, etc.), represented as a bit
> > vector corresponding to the high 8 bits of the file's mode
> > word.
> >
> > qid.vers[4]
> > version number for given path
> >
> > qid.path[8]
> > the file server's unique identification for the file
> >
> > st_mode[4]
> > Permission and flags
> >
> > st_nlink[8]
> > Number of hard links
> >
> > st_uid[4]
> > User id of owner
> >
> > st_gid[4]
> > Group ID of owner
> >
> > st_rdev[8]
> > Device ID (if special file)
> >
> > st_size[8]
> > Size, in bytes
> >
> > st_blksize[8]
> > Block size for file system IO
> >
> > st_blocks[8]
> > Number of file system blocks allocated
> >
> > st_atime_sec[8]
> > Time of last access, seconds
> >
> > st_atime_nsec[8]
> > Time of last access, nanoseconds
> >
> > st_mtime_sec[8]
> > Time of last modification, seconds
> >
> > st_mtime_nsec[8]
> > Time of last modification, nanoseconds
> >
> > st_ctime_sec[8]
> > Time of last status change, seconds
> >
> > st_ctime_nsec[8]
> > Time of last status change, nanoseconds
> >
> >
> > This patch implements the client side of getattr implementation for
> > 9P2000.L.
> > It introduces a new structure p9_stat_dotl for getting Linux stat
> > information
> > along with QID. The data layout is similar to stat structure in Linux user
> > space with the following major differences:
> >
> > inode (st_ino) is not part of data. Instead qid is.
> >
> > device (st_dev) is not part of data because this doesn't make sense on the
> > client.
> >
> > All time variables are 64 bit wide on the wire. The kernel seems to use
> > 32 bit variables for these variables. However, some of the architectures
> > have used 64 bit variables and glibc exposes 64 bit variables to user
> > space on some architectures. Hence to be on the safer side we have made
> > these 64 bit in the protocol. Refer to the comments in
> > include/asm-generic/stat.h
> >
> >
>
> Can we just hold on this patch. There is a discussion to add
> i_generation and inode create time to a variant of stat. So may be the
> protocol bits need those
>
IMHO, we can put this in now and change it later if needed based on how
the discussion about VFS changes go because:
a) 9P2000.L is still at experimental stage, so it allows us to change
the protocol later.
b) The kernel patch for this is already in linux-next. Without these
patches in QEMU it won't be possible to use 9P2000.L.
Thanks,
Sripathi.
> -aneesh
>