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Revision c79ce737

IDc79ce737478bbc419bd107c0bb369c473effef1e

Added by Sripathi Kodi about 11 years ago

virtio-9p: Implement server side of setattr for 9P2000.L protocol.

SYNOPSIS

size[4] Tsetattr tag[2] attr[n]
size[4] Rsetattr tag[2]
DESCRIPTION
The setattr command changes some of the file status information.
attr resembles the iattr structure used in Linux kernel. It
specifies which status parameter is to be changed and to what
value. It is laid out as follows:
valid[4]
specifies which status information is to be changed. Possible
values are:
ATTR_MODE (1 << 0)
ATTR_UID (1 << 1)
ATTR_GID (1 << 2)
ATTR_SIZE (1 << 3)
ATTR_ATIME (1 << 4)
ATTR_MTIME (1 << 5)
ATTR_CTIME (1 << 5)
ATTR_ATIME_SET (1 << 7)
ATTR_MTIME_SET (1 << 8)
The last two bits represent whether the time information
is being sent by the client's user space. In the absense
of these bits the server always uses server's time.
mode[4]
File permission bits
uid[4]
Owner id of file
gid[4]
Group id of the file
size[8]
File size
atime_sec[8]
Time of last file access, seconds
atime_nsec[8]
Time of last file access, nanoseconds
mtime_sec[8]
Time of last file modification, seconds
mtime_nsec[8]
Time of last file modification, nanoseconds

Explanation of the patches:
--------------------------

) The kernel just copies relevent contents of iattr structure to p9_iattr_dotl
structure and passes it down to the client. The only check it has is calling
inode_change_ok()
) The p9_iattr_dotl structure does not have ctime and ia_file parameters because
I don't think these are needed in our case. The client user space can request
updating just ctime by calling chown(fd, -1, -1). This is handled on server
side without a need for putting ctime on the wire.
) The server currently supports changing mode, time, ownership and size of the
file.
) 9P RFC says "Either all the changes in wstat request happen, or none of them
does: if the request succeeds, all changes were made; if it fails, none were."
I have not done anything to implement this specifically because I don't see
a reason.

[: Parts of code for handling chown(-1,-1)

Signed-off-by: Sripathi Kodi <>
Signed-off-by: Venkateswararao Jujjuri <>

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