kernel/git/stable/linux.git/fs/afs/cell.c, branch linux-5.1.y

afs: Fix manually set volume location server list

2019-02-25T19:59:07+00:00

When a cell with a volume location server list is added manually by echoing the details into /proc/net/afs/cells, a record is added but the flag saying it has been looked up isn't set. This causes the VL server rotation code to wait forever, with the top of /proc/pid/stack looking like: afs_select_vlserver+0x3a6/0x6f3 afs_vl_lookup_vldb+0x4b/0x92 afs_create_volume+0x25/0x1b9 ... with the thread stuck in afs_start_vl_iteration() waiting for AFS_CELL_FL_NO_LOOKUP_YET to be cleared. Fix this by clearing AFS_CELL_FL_NO_LOOKUP_YET when setting up a record if that record's details were supplied manually. Fixes: 0a5143f2f89c ("afs: Implement VL server rotation") Reported-by: Dave Botsch Signed-off-by: David Howells Signed-off-by: Linus Torvalds

afs: Fix TTL on VL server and address lists

2018-10-23T23:41:07+00:00

Currently the TTL on VL server and address lists isn't set in all circumstances and may be set to poor choices in others, since the TTL is derived from the SRV/AFSDB DNS record if and when available. Fix the TTL by limiting the range to a minimum and maximum from the current time. At some point these can be made into sysctl knobs. Further, use the TTL we obtained from the upcall to set the expiry on negative results too; in future a mechanism can be added to force reloading of such data. Signed-off-by: David Howells

afs: Implement VL server rotation

2018-10-23T23:41:07+00:00

Track VL servers as independent entities rather than lumping all their addresses together into one set and implement server-level rotation by: (1) Add the concept of a VL server list, where each server has its own separate address list. This code is similar to the FS server list. (2) Use the DNS resolver to retrieve a set of servers and their associated addresses, ports, preference and weight ratings. (3) In the case of a legacy DNS resolver or an address list given directly through /proc/net/afs/cells, create a list containing just a dummy server record and attach all the addresses to that. (4) Implement a simple rotation policy, for the moment ignoring the priorities and weights assigned to the servers. (5) Show the address list through /proc/net/afs//vlservers. This also displays the source and status of the data as indicated by the upcall. Signed-off-by: David Howells

afs: Fix cell proc list

2018-10-12T11:18:57+00:00

Access to the list of cells by /proc/net/afs/cells has a couple of problems: (1) It should be checking against SEQ_START_TOKEN for the keying the header line. (2) It's only holding the RCU read lock, so it can't just walk over the list without following the proper RCU methods. Fix these by using an hlist instead of an ordinary list and using the appropriate accessor functions to follow it with RCU. Since the code that adds a cell to the list must also necessarily change, sort the list on insertion whilst we're at it. Fixes: 989782dcdc91 ("afs: Overhaul cell database management") Signed-off-by: David Howells Signed-off-by: Greg Kroah-Hartman

afs: Display manually added cells in dynamic root mount

2018-06-15T14:27:09+00:00

Alter the dynroot mount so that cells created by manipulation of /proc/fs/afs/cells and /proc/fs/afs/rootcell and by specification of a root cell as a module parameter will cause directories for those cells to be created in the dynamic root superblock for the network namespace[*]. To this end: (1) Only one dynamic root superblock is now created per network namespace and this is shared between all attempts to mount it. This makes it easier to find the superblock to modify. (2) When a dynamic root superblock is created, the list of cells is walked and directories created for each cell already defined. (3) When a new cell is added, if a dynamic root superblock exists, a directory is created for it. (4) When a cell is destroyed, the directory is removed. (5) These directories are created by calling lookup_one_len() on the root dir which automatically creates them if they don't exist. [*] Inasmuch as network namespaces are currently supported here. Signed-off-by: David Howells

afs: Implement network namespacing

2018-05-23T11:01:15+00:00

Implement network namespacing within AFS, but don't yet let mounts occur outside the init namespace. An additional patch will be required propagate the network namespace across automounts. Signed-off-by: David Howells

afs: Mark afs_net::ws_cell as __rcu and set using rcu functions

2018-05-23T10:51:29+00:00

The afs_net::ws_cell member is sometimes used under RCU conditions from within an seq-readlock. It isn't, however, marked __rcu and it isn't set using the proper RCU barrier-imposing functions. Fix this by annotating it with __rcu and using appropriate barriers to make sure accesses are correctly ordered. Without this, the code can produce the following warning: >> fs/afs/proc.c:151:24: sparse: incompatible types in comparison expression (different address spaces) Fixes: f044c8847bb6 ("afs: Lay the groundwork for supporting network namespaces") Reported-by: kbuild test robot Signed-off-by: David Howells

afs: Implement @cell substitution handling

2018-04-09T20:18:58+00:00

Implement @cell substitution handling such that if @cell is seen as a name in a dynamic root mount, then the name of the root cell for that network namespace will be substituted for @cell during lookup. The substitution of @cell for the current net namespace is set by writing the cell name to /proc/fs/afs/rootcell. The value can be obtained by reading the file. For example: # mount -t afs none /kafs -o dyn # echo grand.central.org >/proc/fs/afs/rootcell # ls /kafs/@cell archive/ cvs/ doc/ local/ project/ service/ software/ user/ www/ # cat /proc/fs/afs/rootcell grand.central.org Signed-off-by: David Howells

afs: Don't over-increment the cell usage count when pinning it

2018-04-09T20:12:31+00:00

AFS cells that are added or set as the workstation cell through /proc are pinned against removal by setting the AFS_CELL_FL_NO_GC flag on them and taking a ref. The ref should be only taken if the flag wasn't already set. Fix this by making it conditional. Without this an assertion failure will occur during module removal indicating that the refcount is too elevated. Signed-off-by: David Howells

afs: Fix checker warnings

2018-04-09T20:12:31+00:00

Fix warnings raised by checker, including: (*) Warnings raised by unequal comparison for the purposes of sorting, where the endianness doesn't matter: fs/afs/addr_list.c:246:21: warning: restricted __be16 degrades to integer fs/afs/addr_list.c:246:30: warning: restricted __be16 degrades to integer fs/afs/addr_list.c:248:21: warning: restricted __be32 degrades to integer fs/afs/addr_list.c:248:49: warning: restricted __be32 degrades to integer fs/afs/addr_list.c:283:21: warning: restricted __be16 degrades to integer fs/afs/addr_list.c:283:30: warning: restricted __be16 degrades to integer (*) afs_set_cb_interest() is not actually used and can be removed. (*) afs_cell_gc_delay() should be provided with a sysctl. (*) afs_cell_destroy() needs to use rcu_access_pointer() to read cell->vl_addrs. (*) afs_init_fs_cursor() should be static. (*) struct afs_vnode::permit_cache needs to be marked __rcu. (*) afs_server_rcu() needs to use rcu_access_pointer(). (*) afs_destroy_server() should use rcu_access_pointer() on server->addresses as the server object is no longer accessible. (*) afs_find_server() casts __be16/__be32 values to int in order to directly compare them for the purpose of finding a match in a list, but is should also annotate the cast with __force to avoid checker warnings. (*) afs_check_permit() accesses vnode->permit_cache outside of the RCU readlock, though it doesn't then access the value; the extraneous access is deleted. False positives: (*) Conditional locking around the code in xdr_decode_AFSFetchStatus. This can be dealt with in a separate patch. fs/afs/fsclient.c:148:9: warning: context imbalance in 'xdr_decode_AFSFetchStatus' - different lock contexts for basic block (*) Incorrect handling of seq-retry lock context balance: fs/afs/inode.c:455:38: warning: context imbalance in 'afs_getattr' - different lock contexts for basic block fs/afs/server.c:52:17: warning: context imbalance in 'afs_find_server' - different lock contexts for basic block fs/afs/server.c:128:17: warning: context imbalance in 'afs_find_server_by_uuid' - different lock contexts for basic block Errors: (*) afs_lookup_cell_rcu() needs to break out of the seq-retry loop, not go round again if it successfully found the workstation cell. (*) Fix UUID decode in afs_deliver_cb_probe_uuid(). (*) afs_cache_permit() has a missing rcu_read_unlock() before one of the jumps to the someone_else_changed_it label. Move the unlock to after the label. (*) afs_vl_get_addrs_u() is using ntohl() rather than htonl() when encoding to XDR. (*) afs_deliver_yfsvl_get_endpoints() is using htonl() rather than ntohl() when decoding from XDR. Signed-off-by: David Howells