linux/fs/fscache
David Howells e3d4d28b1c FS-Cache: Handle read request vs lookup, creation or other cache failure
FS-Cache doesn't correctly handle the netfs requesting a read from the cache
on an object that failed or was withdrawn by the cache.  A trace similar to
the following might be seen:

	CacheFiles: Lookup failed error -105
	[exe   ] unexpected submission OP165afe [OBJ6cac OBJECT_LC_DYING]
	[exe   ] objstate=OBJECT_LC_DYING [OBJECT_LC_DYING]
	[exe   ] objflags=0
	[exe   ] objevent=9 [fffffffffffffffb]
	[exe   ] ops=0 inp=0 exc=0
	Pid: 6970, comm: exe Not tainted 2.6.32-rc6-cachefs #50
	Call Trace:
	 [<ffffffffa0076477>] fscache_submit_op+0x3ff/0x45a [fscache]
	 [<ffffffffa0077997>] __fscache_read_or_alloc_pages+0x187/0x3c4 [fscache]
	 [<ffffffffa00b6480>] ? nfs_readpage_from_fscache_complete+0x0/0x66 [nfs]
	 [<ffffffffa00b6388>] __nfs_readpages_from_fscache+0x7e/0x176 [nfs]
	 [<ffffffff8108e483>] ? __alloc_pages_nodemask+0x11c/0x5cf
	 [<ffffffffa009d796>] nfs_readpages+0x114/0x1d7 [nfs]
	 [<ffffffff81090314>] __do_page_cache_readahead+0x15f/0x1ec
	 [<ffffffff81090228>] ? __do_page_cache_readahead+0x73/0x1ec
	 [<ffffffff810903bd>] ra_submit+0x1c/0x20
	 [<ffffffff810906bb>] ondemand_readahead+0x227/0x23a
	 [<ffffffff81090762>] page_cache_sync_readahead+0x17/0x19
	 [<ffffffff8108a99e>] generic_file_aio_read+0x236/0x5a0
	 [<ffffffffa00937bd>] nfs_file_read+0xe4/0xf3 [nfs]
	 [<ffffffff810b2fa2>] do_sync_read+0xe3/0x120
	 [<ffffffff81354cc3>] ? _spin_unlock_irq+0x2b/0x31
	 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34
	 [<ffffffff811848e5>] ? selinux_file_permission+0x5d/0x10f
	 [<ffffffff81352bdb>] ? thread_return+0x3e/0x101
	 [<ffffffff8117d7b0>] ? security_file_permission+0x11/0x13
	 [<ffffffff810b3b06>] vfs_read+0xaa/0x16f
	 [<ffffffff81058df0>] ? trace_hardirqs_on_caller+0x10c/0x130
	 [<ffffffff810b3c84>] sys_read+0x45/0x6c
	 [<ffffffff8100ae2b>] system_call_fastpath+0x16/0x1b

The object state might also be OBJECT_DYING or OBJECT_WITHDRAWING.

This should be handled by simply rejecting the new operation with ENOBUFS.
There's no need to log an error for it.  Events of this type now appear in the
stats file under Ops:rej.

Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 18:11:32 +00:00
..
cache.c FS-Cache: Add counters for entry/exit to/from cache operation functions 2009-11-19 18:11:08 +00:00
cookie.c FS-Cache: Fix lock misorder in fscache_write_op() 2009-11-19 18:11:25 +00:00
fsdef.c FS-Cache: Root index definition 2009-04-03 16:42:37 +01:00
histogram.c FS-Cache: Add use of /proc and presentation of statistics 2009-04-03 16:42:37 +01:00
internal.h FS-Cache: Handle read request vs lookup, creation or other cache failure 2009-11-19 18:11:32 +00:00
Kconfig FS-Cache: Allow the current state of all objects to be dumped 2009-11-19 18:11:04 +00:00
main.c SLOW_WORK: Wait for outstanding work items belonging to a module to clear 2009-11-19 18:10:23 +00:00
Makefile FS-Cache: Allow the current state of all objects to be dumped 2009-11-19 18:11:04 +00:00
netfs.c FS-Cache: Add netfs registration 2009-04-03 16:42:38 +01:00
object-list.c FS-Cache: Allow the current state of all objects to be dumped 2009-11-19 18:11:04 +00:00
object.c FS-Cache: The object-available state can't rely on the cookie to be available 2009-11-19 18:11:22 +00:00
operation.c FS-Cache: Handle read request vs lookup, creation or other cache failure 2009-11-19 18:11:32 +00:00
page.c FS-Cache: Don't delete pending pages from the page-store tracking tree 2009-11-19 18:11:29 +00:00
proc.c FS-Cache: Allow the current state of all objects to be dumped 2009-11-19 18:11:04 +00:00
stats.c FS-Cache: Handle read request vs lookup, creation or other cache failure 2009-11-19 18:11:32 +00:00