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The current code assumes that volumes and servers are per-cell and are
never shared, but this is not enforced, and, indeed, public cells do exist
that are aliases of each other. Further, an organisation can, say, set up
a public cell and a private cell with overlapping, but not identical, sets
of servers. The difference is purely in the database attached to the VL
servers.
The current code will malfunction if it sees a server in two cells as it
assumes global address -> server record mappings and that each server is in
just one cell.
Further, each server may have multiple addresses - and may have addresses
of different families (IPv4 and IPv6, say).
To this end, the following structural changes are made:
(1) Server record management is overhauled:
(a) Server records are made independent of cell. The namespace keeps
track of them, volume records have lists of them and each vnode
has a server on which its callback interest currently resides.
(b) The cell record no longer keeps a list of servers known to be in
that cell.
(c) The server records are now kept in a flat list because there's no
single address to sort on.
(d) Server records are now keyed by their UUID within the namespace.
(e) The addresses for a server are obtained with the VL.GetAddrsU
rather than with VL.GetEntryByName, using the server's UUID as a
parameter.
(f) Cached server records are garbage collected after a period of
non-use and are counted out of existence before purging is allowed
to complete. This protects the work functions against rmmod.
(g) The servers list is now in /proc/fs/afs/servers.
(2) Volume record management is overhauled:
(a) An RCU-replaceable server list is introduced. This tracks both
servers and their coresponding callback interests.
(b) The superblock is now keyed on cell record and numeric volume ID.
(c) The volume record is now tied to the superblock which mounts it,
and is activated when mounted and deactivated when unmounted.
This makes it easier to handle the cache cookie without causing a
double-use in fscache.
(d) The volume record is loaded from the VLDB using VL.GetEntryByNameU
to get the server UUID list.
(e) The volume name is updated if it is seen to have changed when the
volume is updated (the update is keyed on the volume ID).
(3) The vlocation record is got rid of and VLDB records are no longer
cached. Sufficient information is stored in the volume record, though
an update to a volume record is now no longer shared between related
volumes (volumes come in bundles of three: R/W, R/O and backup).
and the following procedural changes are made:
(1) The fileserver cursor introduced previously is now fleshed out and
used to iterate over fileservers and their addresses.
(2) Volume status is checked during iteration, and the server list is
replaced if a change is detected.
(3) Server status is checked during iteration, and the address list is
replaced if a change is detected.
(4) The abort code is saved into the address list cursor and -ECONNABORTED
returned in afs_make_call() if a remote abort happened rather than
translating the abort into an error message. This allows actions to
be taken depending on the abort code more easily.
(a) If a VMOVED abort is seen then this is handled by rechecking the
volume and restarting the iteration.
(b) If a VBUSY, VRESTARTING or VSALVAGING abort is seen then this is
handled by sleeping for a short period and retrying and/or trying
other servers that might serve that volume. A message is also
displayed once until the condition has cleared.
(c) If a VOFFLINE abort is seen, then this is handled as VBUSY for the
moment.
(d) If a VNOVOL abort is seen, the volume is rechecked in the VLDB to
see if it has been deleted; if not, the fileserver is probably
indicating that the volume couldn't be attached and needs
salvaging.
(e) If statfs() sees one of these aborts, it does not sleep, but
rather returns an error, so as not to block the umount program.
(5) The fileserver iteration functions in vnode.c are now merged into
their callers and more heavily macroised around the cursor. vnode.c
is removed.
(6) Operations on a particular vnode are serialised on that vnode because
the server will lock that vnode whilst it operates on it, so a second
op sent will just have to wait.
(7) Fileservers are probed with FS.GetCapabilities before being used.
This is where service upgrade will be done.
(8) A callback interest on a fileserver is set up before an FS operation
is performed and passed through to afs_make_call() so that it can be
set on the vnode if the operation returns a callback. The callback
interest is passed through to afs_iget() also so that it can be set
there too.
In general, record updating is done on an as-needed basis when we try to
access servers, volumes or vnodes rather than offloading it to work items
and special threads.
Notes:
(1) Pre AFS-3.4 servers are no longer supported, though this can be added
back if necessary (AFS-3.4 was released in 1998).
(2) VBUSY is retried forever for the moment at intervals of 1s.
(3) /proc/fs/afs/<cell>/servers no longer exists.
Signed-off-by: David Howells <dhowells@redhat.com>
63 lines
2.6 KiB
C
63 lines
2.6 KiB
C
/* AFS File Service definitions
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*
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* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef AFS_FS_H
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#define AFS_FS_H
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#define AFS_FS_PORT 7000 /* AFS file server port */
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#define FS_SERVICE 1 /* AFS File Service ID */
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enum AFS_FS_Operations {
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FSFETCHDATA = 130, /* AFS Fetch file data */
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FSFETCHSTATUS = 132, /* AFS Fetch file status */
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FSSTOREDATA = 133, /* AFS Store file data */
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FSSTORESTATUS = 135, /* AFS Store file status */
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FSREMOVEFILE = 136, /* AFS Remove a file */
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FSCREATEFILE = 137, /* AFS Create a file */
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FSRENAME = 138, /* AFS Rename or move a file or directory */
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FSSYMLINK = 139, /* AFS Create a symbolic link */
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FSLINK = 140, /* AFS Create a hard link */
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FSMAKEDIR = 141, /* AFS Create a directory */
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FSREMOVEDIR = 142, /* AFS Remove a directory */
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FSGIVEUPCALLBACKS = 147, /* AFS Discard callback promises */
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FSGETVOLUMEINFO = 148, /* AFS Get information about a volume */
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FSGETVOLUMESTATUS = 149, /* AFS Get volume status information */
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FSGETROOTVOLUME = 151, /* AFS Get root volume name */
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FSSETLOCK = 156, /* AFS Request a file lock */
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FSEXTENDLOCK = 157, /* AFS Extend a file lock */
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FSRELEASELOCK = 158, /* AFS Release a file lock */
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FSLOOKUP = 161, /* AFS lookup file in directory */
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FSFETCHDATA64 = 65537, /* AFS Fetch file data */
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FSSTOREDATA64 = 65538, /* AFS Store file data */
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FSGIVEUPALLCALLBACKS = 65539, /* AFS Give up all outstanding callbacks on a server */
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FSGETCAPABILITIES = 65540, /* Probe and get the capabilities of a fileserver */
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};
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enum AFS_FS_Errors {
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VRESTARTING = -100, /* Server is restarting */
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VSALVAGE = 101, /* volume needs salvaging */
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VNOVNODE = 102, /* no such file/dir (vnode) */
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VNOVOL = 103, /* no such volume or volume unavailable */
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VVOLEXISTS = 104, /* volume name already exists */
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VNOSERVICE = 105, /* volume not currently in service */
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VOFFLINE = 106, /* volume is currently offline (more info available [VVL-spec]) */
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VONLINE = 107, /* volume is already online */
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VDISKFULL = 108, /* disk partition is full */
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VOVERQUOTA = 109, /* volume's maximum quota exceeded */
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VBUSY = 110, /* volume is temporarily unavailable */
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VMOVED = 111, /* volume moved to new server - ask this FS where */
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VIO = 112, /* I/O error in volume */
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VSALVAGING = 113, /* Volume is being salvaged */
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VRESTRICTED = 120, /* Volume is restricted from using */
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};
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#endif /* AFS_FS_H */
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