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| author | David Howells <dhowells@redhat.com> | 2009-11-19 13:11:32 -0500 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2009-11-19 13:11:32 -0500 |
| commit | e3d4d28b1c8cc7c26536a50b43d86ccd39878550 (patch) | |
| tree | 23f6dacd5ffdf6c6d01c411517855a41405381b9 /Documentation/filesystems/caching/fscache.txt | |
| parent | 285e728b0ac55b53a673114096168d6f74930167 (diff) | |
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on an object that failed or was withdrawn by the cache.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>
Diffstat (limited to 'Documentation/filesystems/caching/fscache.txt')
| -rw-r--r-- | Documentation/filesystems/caching/fscache.txt | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/Documentation/filesystems/caching/fscache.txt b/Documentation/filesystems/caching/fscache.txt index 9cf2cfbc81c9..057a3c71d524 100644 --- a/Documentation/filesystems/caching/fscache.txt +++ b/Documentation/filesystems/caching/fscache.txt | |||
| @@ -276,6 +276,7 @@ proc files. | |||
| 276 | run=N Number of times async ops given CPU time | 276 | run=N Number of times async ops given CPU time |
| 277 | enq=N Number of times async ops queued for processing | 277 | enq=N Number of times async ops queued for processing |
| 278 | can=N Number of async ops cancelled | 278 | can=N Number of async ops cancelled |
| 279 | rej=N Number of async ops rejected due to object lookup/create failure | ||
| 279 | dfr=N Number of async ops queued for deferred release | 280 | dfr=N Number of async ops queued for deferred release |
| 280 | rel=N Number of async ops released | 281 | rel=N Number of async ops released |
| 281 | gc=N Number of deferred-release async ops garbage collected | 282 | gc=N Number of deferred-release async ops garbage collected |