kernel.git/fs/afs/volume.c, branch linux-4.16.y

afs: Fix server list handling

2018-02-06T14:36:54Z

Fix server list handling in the following ways: (1) In afs_alloc_volume(), remove duplicate server list build code. This was already done by afs_alloc_server_list() which afs_alloc_volume() previously called. This just results in twice as many VL RPCs. (2) In afs_deliver_vl_get_entry_by_name_u(), use the number of server records indicated by ->nServers in the UVLDB record returned by the VL.GetEntryByNameU RPC call rather than scanning all NMAXNSERVERS slots. Unused slots may contain garbage. (3) In afs_alloc_server_list(), don't stop converting a UVLDB record into a server list just because we can't look up one of the servers. Just skip that server and go on to the next. If we can't look up any of the servers then we'll fail at the end. Without this patch, an attempt to view the umich.edu root cell using something like "ls /afs/umich.edu" on a dynamic root (future patch) mount or an autocell mount will result in ENOMEDIUM. The failure is due to kafs not stopping after nServers'worth of records have been read, but then trying to access a server with a garbage UUID and getting an error, which aborts the server list build. Fixes: d2ddc776a458 ("afs: Overhaul volume and server record caching and fileserver rotation") Reported-by: Jonathan Billings Signed-off-by: David Howells cc: stable@vger.kernel.org

afs: Add missing afs_put_cell()

2018-02-06T14:22:03Z

afs_alloc_volume() needs to release the cell ref it obtained in the case of an error. Fix this by adding an afs_put_cell() call into the error path. This can triggered when a lookup for a cell in a dynamic root or an autocell mount returns an error whilst trying to look up the server (such as ENOMEDIUM). This results in an assertion failure oops when the module is unloaded due to outstanding refs on a cell record. Fixes: d2ddc776a458 ("afs: Overhaul volume and server record caching and fileserver rotation") Signed-off-by: David Howells cc: stable@vger.kernel.org

afs: Make use of the YFS service upgrade to fully support IPv6

2017-11-13T15:38:19Z

YFS VL servers offer an upgraded Volume Location service that can return IPv6 addresses to fileservers and volume servers in addition to IPv4 addresses using the YFSVL.GetEndpoints operation which we should use if it's available. To this end: (1) Make rxrpc_kernel_recv_data() return the call's current service ID so that the caller can detect service upgrade and see what the service was upgraded to. (2) When we see a VL server address we haven't seen before, send a VL.GetCapabilities operation to it with the service upgrade bit set. If we get an upgrade to the YFS VL service, change the service ID in the address list for that address to use the upgraded service and set a flag to note that this appears to be a YFS-compatible server. (3) If, when a server's addresses are being looked up, we note that we previously detected a YFS-compatible server, then send the YFSVL.GetEndpoints operation rather than VL.GetAddrsU. (4) Build a fileserver address list from the reply of YFSVL.GetEndpoints, including both IPv4 and IPv6 addresses. Volume server addresses are discarded. (5) The address list is sorted by address and port now, instead of just address. This allows multiple servers on the same host sitting on different ports. Signed-off-by: David Howells

afs: Overhaul volume and server record caching and fileserver rotation

2017-11-13T15:38:19Z

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//servers no longer exists. Signed-off-by: David Howells

afs: Move server rotation code into its own file

2017-11-13T15:38:19Z

Move server rotation code into its own file. Signed-off-by: David Howells

afs: Add an address list concept

2017-11-13T15:38:18Z

Add an RCU replaceable address list structure to hold a list of server addresses. The list also holds the To this end: (1) A cell's VL server address list can be loaded directly via insmod or echo to /proc/fs/afs/cells or dynamically from a DNS query for AFSDB or SRV records. (2) Anyone wanting to use a cell's VL server address must wait until the cell record comes online and has tried to obtain some addresses. (3) An FS server's address list, for the moment, has a single entry that is the key to the server list. This will change in the future when a server is instead keyed on its UUID and the VL.GetAddrsU operation is used. (4) An 'address cursor' concept is introduced to handle iteration through the address list. This is passed to the afs_make_call() as, in the future, stuff (such as abort code) that doesn't outlast the call will be returned in it. In the future, we might want to annotate the list with information about how each address fares. We might then want to propagate such annotations over address list replacement. Whilst we're at it, we allow IPv6 addresses to be specified in colon-delimited lists by enclosing them in square brackets. Signed-off-by: David Howells

afs: Overhaul the callback handling

2017-11-13T15:38:18Z

Overhaul the AFS callback handling by the following means: (1) Don't give up callback promises on vnodes that we are no longer using, rather let them just expire on the server or let the server break them. This is actually more efficient for the server as the callback lookup is expensive if there are lots of extant callbacks. (2) Only give up the callback promises we have from a server when the server record is destroyed. Then we can just give up *all* the callback promises on it in one go. (3) Servers can end up being shared between cells if cells are aliased, so don't add all the vnodes being backed by a particular server into a big FID-indexed tree on that server as there may be duplicates. Instead have each volume instance (~= superblock) register an interest in a server as it starts to make use of it and use this to allow the processor for callbacks from the server to find the superblock and thence the inode corresponding to the FID being broken by means of ilookup_nowait(). (4) Rather than iterating over the entire callback list when a mass-break comes in from the server, maintain a counter of mass-breaks in afs_server (cb_seq) and make afs_validate() check it against the copy in afs_vnode. It would be nice not to have to take a read_lock whilst doing this, but that's tricky without using RCU. (5) Save a ref on the fileserver we're using for a call in the afs_call struct so that we can access its cb_s_break during call decoding. (6) Write-lock around callback and status storage in a vnode and read-lock around getattr so that we don't see the status mid-update. This has the following consequences: (1) Data invalidation isn't seen until someone calls afs_validate() on a vnode. Unfortunately, we need to use a key to query the server, but getting one from a background thread is tricky without caching loads of keys all over the place. (2) Mass invalidation isn't seen until someone calls afs_validate(). (3) Callback breaking is going to hit the inode_hash_lock quite a bit. Could this be replaced with rcu_read_lock() since inodes are destroyed under RCU conditions. Signed-off-by: David Howells

afs: Keep and pass sockaddr_rxrpc addresses rather than in_addr

2017-11-13T15:38:17Z

Keep and pass sockaddr_rxrpc addresses around rather than keeping and passing in_addr addresses to allow for the use of IPv6 and non-standard port numbers in future. This also allows the port and service_id fields to be removed from the afs_call struct. Signed-off-by: David Howells

afs: Update the cache index structure

2017-11-13T15:38:17Z

Update the cache index structure in the following ways: (1) Don't use the volume name followed by the volume type as levels in the cache index. Volumes can be renamed. Use the volume ID instead. (2) Don't store the VLDB data for a volume in the tree. If the volume database should be cached locally, then it should be done in a separate tree. (3) Expand the volume ID stored in the cache to 64 bits. (4) Expand the file/vnode ID stored in the cache to 96 bits. (5) Increment the cache structure version number to 1. Signed-off-by: David Howells

afs: Push the net ns pointer to more places

2017-11-13T15:38:17Z

Push the network namespace pointer to more places in AFS, including the afs_server structure (which doesn't hold a ref on the netns). In particular, afs_put_cell() now takes requires a net ns parameter so that it can safely alter the netns after decrementing the cell usage count - the cell will be deallocated by a background thread after being cached for a period, which means that it's not safe to access it after reducing its usage count. Signed-off-by: David Howells