mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-25 02:09:42 +00:00
![Masanari Iida](/assets/img/avatar_default.png)
Signed-off-by: Masanari Iida <standby24x7@gmail.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
227 lines
6.9 KiB
Text
227 lines
6.9 KiB
Text
POHMELFS network protocol.
|
|
|
|
Basic structure used in network communication is following command:
|
|
|
|
struct netfs_cmd
|
|
{
|
|
__u16 cmd; /* Command number */
|
|
__u16 csize; /* Attached crypto information size */
|
|
__u16 cpad; /* Attached padding size */
|
|
__u16 ext; /* External flags */
|
|
__u32 size; /* Size of the attached data */
|
|
__u32 trans; /* Transaction id */
|
|
__u64 id; /* Object ID to operate on. Used for feedback.*/
|
|
__u64 start; /* Start of the object. */
|
|
__u64 iv; /* IV sequence */
|
|
__u8 data[0];
|
|
};
|
|
|
|
Commands can be embedded into transaction command (which in turn has own command),
|
|
so one can extend protocol as needed without breaking backward compatibility as long
|
|
as old commands are supported. All string lengths include tail 0 byte.
|
|
|
|
All commands are transferred over the network in big-endian. CPU endianness is used at the end peers.
|
|
|
|
@cmd - command number, which specifies command to be processed. Following
|
|
commands are used currently:
|
|
|
|
NETFS_READDIR = 1, /* Read directory for given inode number */
|
|
NETFS_READ_PAGE, /* Read data page from the server */
|
|
NETFS_WRITE_PAGE, /* Write data page to the server */
|
|
NETFS_CREATE, /* Create directory entry */
|
|
NETFS_REMOVE, /* Remove directory entry */
|
|
NETFS_LOOKUP, /* Lookup single object */
|
|
NETFS_LINK, /* Create a link */
|
|
NETFS_TRANS, /* Transaction */
|
|
NETFS_OPEN, /* Open intent */
|
|
NETFS_INODE_INFO, /* Metadata cache coherency synchronization message */
|
|
NETFS_PAGE_CACHE, /* Page cache invalidation message */
|
|
NETFS_READ_PAGES, /* Read multiple contiguous pages in one go */
|
|
NETFS_RENAME, /* Rename object */
|
|
NETFS_CAPABILITIES, /* Capabilities of the client, for example supported crypto */
|
|
NETFS_LOCK, /* Distributed lock message */
|
|
NETFS_XATTR_SET, /* Set extended attribute */
|
|
NETFS_XATTR_GET, /* Get extended attribute */
|
|
|
|
@ext - external flags. Used by different commands to specify some extra arguments
|
|
like partial size of the embedded objects or creation flags.
|
|
|
|
@size - size of the attached data. For NETFS_READ_PAGE and NETFS_READ_PAGES no data is attached,
|
|
but size of the requested data is incorporated here. It does not include size of the command
|
|
header (struct netfs_cmd) itself.
|
|
|
|
@id - id of the object this command operates on. Each command can use it for own purpose.
|
|
|
|
@start - start of the object this command operates on. Each command can use it for own purpose.
|
|
|
|
@csize, @cpad - size and padding size of the (attached if needed) crypto information.
|
|
|
|
Command specifications.
|
|
|
|
@NETFS_READDIR
|
|
This command is used to sync content of the remote dir to the client.
|
|
|
|
@ext - length of the path to object.
|
|
@size - the same.
|
|
@id - local inode number of the directory to read.
|
|
@start - zero.
|
|
|
|
|
|
@NETFS_READ_PAGE
|
|
This command is used to read data from remote server.
|
|
Data size does not exceed local page cache size.
|
|
|
|
@id - inode number.
|
|
@start - first byte offset.
|
|
@size - number of bytes to read plus length of the path to object.
|
|
@ext - object path length.
|
|
|
|
|
|
@NETFS_CREATE
|
|
Used to create object.
|
|
It does not require that all directories on top of the object were
|
|
already created, it will create them automatically. Each object has
|
|
associated @netfs_path_entry data structure, which contains creation
|
|
mode (permissions and type) and length of the name as long as name itself.
|
|
|
|
@start - 0
|
|
@size - size of the all data structures needed to create a path
|
|
@id - local inode number
|
|
@ext - 0
|
|
|
|
|
|
@NETFS_REMOVE
|
|
Used to remove object.
|
|
|
|
@ext - length of the path to object.
|
|
@size - the same.
|
|
@id - local inode number.
|
|
@start - zero.
|
|
|
|
|
|
@NETFS_LOOKUP
|
|
Lookup information about object on server.
|
|
|
|
@ext - length of the path to object.
|
|
@size - the same.
|
|
@id - local inode number of the directory to look object in.
|
|
@start - local inode number of the object to look at.
|
|
|
|
|
|
@NETFS_LINK
|
|
Create hard of symlink.
|
|
Command is sent as "object_path|target_path".
|
|
|
|
@size - size of the above string.
|
|
@id - parent local inode number.
|
|
@start - 1 for symlink, 0 for hardlink.
|
|
@ext - size of the "object_path" above.
|
|
|
|
|
|
@NETFS_TRANS
|
|
Transaction header.
|
|
|
|
@size - incorporates all embedded command sizes including theirs header sizes.
|
|
@start - transaction generation number - unique id used to find transaction.
|
|
@ext - transaction flags. Unused at the moment.
|
|
@id - 0.
|
|
|
|
|
|
@NETFS_OPEN
|
|
Open intent for given transaction.
|
|
|
|
@id - local inode number.
|
|
@start - 0.
|
|
@size - path length to the object.
|
|
@ext - open flags (O_RDWR and so on).
|
|
|
|
|
|
@NETFS_INODE_INFO
|
|
Metadata update command.
|
|
It is sent to servers when attributes of the object are changed and received
|
|
when data or metadata were updated. It operates with the following structure:
|
|
|
|
struct netfs_inode_info
|
|
{
|
|
unsigned int mode;
|
|
unsigned int nlink;
|
|
unsigned int uid;
|
|
unsigned int gid;
|
|
unsigned int blocksize;
|
|
unsigned int padding;
|
|
__u64 ino;
|
|
__u64 blocks;
|
|
__u64 rdev;
|
|
__u64 size;
|
|
__u64 version;
|
|
};
|
|
|
|
It effectively mirrors stat(2) returned data.
|
|
|
|
|
|
@ext - path length to the object.
|
|
@size - the same plus size of the netfs_inode_info structure.
|
|
@id - local inode number.
|
|
@start - 0.
|
|
|
|
|
|
@NETFS_PAGE_CACHE
|
|
Command is only received by clients. It contains information about
|
|
page to be marked as not up-to-date.
|
|
|
|
@id - client's inode number.
|
|
@start - last byte of the page to be invalidated. If it is not equal to
|
|
current inode size, it will be vmtruncated().
|
|
@size - 0
|
|
@ext - 0
|
|
|
|
|
|
@NETFS_READ_PAGES
|
|
Used to read multiple contiguous pages in one go.
|
|
|
|
@start - first byte of the contiguous region to read.
|
|
@size - contains of two fields: lower 8 bits are used to represent page cache shift
|
|
used by client, another 3 bytes are used to get number of pages.
|
|
@id - local inode number.
|
|
@ext - path length to the object.
|
|
|
|
|
|
@NETFS_RENAME
|
|
Used to rename object.
|
|
Attached data is formed into following string: "old_path|new_path".
|
|
|
|
@id - local inode number.
|
|
@start - parent inode number.
|
|
@size - length of the above string.
|
|
@ext - length of the old path part.
|
|
|
|
|
|
@NETFS_CAPABILITIES
|
|
Used to exchange crypto capabilities with server.
|
|
If crypto capabilities are not supported by server, then client will disable it
|
|
or fail (if 'crypto_fail_unsupported' mount options was specified).
|
|
|
|
@id - superblock index. Used to specify crypto information for group of servers.
|
|
@size - size of the attached capabilities structure.
|
|
@start - 0.
|
|
@size - 0.
|
|
@scsize - 0.
|
|
|
|
@NETFS_LOCK
|
|
Used to send lock request/release messages. Although it sends byte range request
|
|
and is capable of flushing pages based on that, it is not used, since all Linux
|
|
filesystems lock the whole inode.
|
|
|
|
@id - lock generation number.
|
|
@start - start of the locked range.
|
|
@size - size of the locked range.
|
|
@ext - lock type: read/write. Not used actually. 15'th bit is used to determine,
|
|
if it is lock request (1) or release (0).
|
|
|
|
@NETFS_XATTR_SET
|
|
@NETFS_XATTR_GET
|
|
Used to set/get extended attributes for given inode.
|
|
@id - attribute generation number or xattr setting type
|
|
@start - size of the attribute (request or attached)
|
|
@size - name length, path len and data size for given attribute
|
|
@ext - path length for given object
|