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  1. Apr 09, 2018
    • David Howells's avatar
      afs: Prospectively look up extra files when doing a single lookup · 5cf9dd55
      David Howells authored 
      

When afs_lookup() is called, prospectively look up the next 50 uncached
fids also from that same directory and cache the results, rather than just
looking up the one file requested.

This allows us to use the FS.InlineBulkStatus RPC op to increase efficiency
by fetching up to 50 file statuses at a time.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      5cf9dd55
    • David Howells's avatar
      afs: Don't over-increment the cell usage count when pinning it · 17814aef
      David Howells authored 
      

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: default avatarDavid Howells <dhowells@redhat.com>
      17814aef
    • David Howells's avatar
      afs: Fix checker warnings · fe342cf7
      David Howells authored 
      

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: default avatarDavid Howells <dhowells@redhat.com>
      fe342cf7
  3. Apr 08, 2018
  5. Apr 06, 2018
  7. Apr 04, 2018
    • David Howells's avatar
      fscache: Attach the index key and aux data to the cookie · 402cb8dd
      David Howells authored 
      

Attach copies of the index key and auxiliary data to the fscache cookie so
that:

 (1) The callbacks to the netfs for this stuff can be eliminated.  This
     can simplify things in the cache as the information is still
     available, even after the cache has relinquished the cookie.

 (2) Simplifies the locking requirements of accessing the information as we
     don't have to worry about the netfs object going away on us.

 (3) The cache can do lazy updating of the coherency information on disk.
     As long as the cache is flushed before reboot/poweroff, there's no
     need to update the coherency info on disk every time it changes.

 (4) Cookies can be hashed or put in a tree as the index key is easily
     available.  This allows:

     (a) Checks for duplicate cookies can be made at the top fscache layer
     	 rather than down in the bowels of the cache backend.

     (b) Caching can be added to a netfs object that has a cookie if the
     	 cache is brought online after the netfs object is allocated.

A certain amount of space is made in the cookie for inline copies of the
data, but if it won't fit there, extra memory will be allocated for it.

The downside of this is that live cache operation requires more memory.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Acked-by: default avatarAnna Schumaker <anna.schumaker@netapp.com>
Tested-by: default avatarSteve Dickson <steved@redhat.com>
      402cb8dd
    • David Howells's avatar
      fscache: Add more tracepoints · 08c2e3d0
      David Howells authored 
      

Add more tracepoints to fscache, including:

 (*) fscache_page - Tracks netfs pages known to fscache.

 (*) fscache_check_page - Tracks the netfs querying whether a page is
     pending storage.

 (*) fscache_wake_cookie - Tracks cookies being woken up after a page
     completes/aborts storage in the cache.

 (*) fscache_op - Tracks operations being initialised.

 (*) fscache_wrote_page - Tracks return of the backend write_page op.

 (*) fscache_gang_lookup - Tracks lookup of pages to be stored in the write
     operation.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      08c2e3d0
    • David Howells's avatar
      fscache: Add tracepoints · a18feb55
      David Howells authored 
      

Add some tracepoints to fscache:

 (*) fscache_cookie - Tracks a cookie's usage count.

 (*) fscache_netfs - Logs registration of a network filesystem, including
     the pointer to the cookie allocated.

 (*) fscache_acquire - Logs cookie acquisition.

 (*) fscache_relinquish - Logs cookie relinquishment.

 (*) fscache_enable - Logs enablement of a cookie.

 (*) fscache_disable - Logs disablement of a cookie.

 (*) fscache_osm - Tracks execution of states in the object state machine.

and cachefiles:

 (*) cachefiles_ref - Tracks a cachefiles object's usage count.

 (*) cachefiles_lookup - Logs result of lookup_one_len().

 (*) cachefiles_mkdir - Logs result of vfs_mkdir().

 (*) cachefiles_create - Logs result of vfs_create().

 (*) cachefiles_unlink - Logs calls to vfs_unlink().

 (*) cachefiles_rename - Logs calls to vfs_rename().

 (*) cachefiles_mark_active - Logs an object becoming active.

 (*) cachefiles_wait_active - Logs a wait for an old object to be
     destroyed.

 (*) cachefiles_mark_inactive - Logs an object becoming inactive.

 (*) cachefiles_mark_buried - Logs the burial of an object.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      a18feb55
    • David Howells's avatar
      fscache: Fix hanging wait on page discarded by writeback · 2c984257
      David Howells authored 
      

If the fscache asynchronous write operation elects to discard a page that's
pending storage to the cache because the page would be over the store limit
then it needs to wake the page as someone may be waiting on completion of
the write.

The problem is that the store limit may be updated by a different
asynchronous operation - and so may miss the write - and that the store
limit may not even get updated until later by the netfs.

Fix the kernel hang by making fscache_write_op() mark as written any pages
that are over the limit.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      2c984257