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authorDavid Howells <dhowells@redhat.com>2012-12-07 10:41:26 +0000
committerDavid Howells <dhowells@redhat.com>2012-12-20 22:20:40 +0000
commit7ef001e937e8b9cbedb2fc1c31dd681ac3b31927 (patch)
tree50382e120103b9038b8fb66c474949f134109267 /fs/fscache
parent9c04caa81b876faee5f1cc6eaad76dd7021ab8ff (diff)
FS-Cache: One of the write operation paths doesn't set the object state
In fscache_write_op(), if the object is determined to have become inactive or to have lost its cookie, we don't move the operation state from in-progress, and so an assertion in fscache_put_operation() fails with an assertion (see below). Instrumenting fscache_op_work_func() indicates that it called fscache_write_op() before calling fscache_put_operation() - where the assertion failed. The assertion at line 433 indicates that the operation state is IN_PROGRESS rather than being COMPLETE or CANCELLED. Instrumenting fscache_write_op() showed that it was being called on an object that had had its cookie removed and that this was due to relinquishment of the cookie by the netfs. At this point fscache no longer has access to the pages of netfs data that were requested to be written, and so simply cancelling the operation is the thing to do. FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:433! invalid opcode: 0000 [#1] SMP Modules linked in: cachefiles(F) nfsv4(F) nfsv3(F) nfsv2(F) nfs(F) fscache(F) auth_rpcgss(F) nfs_acl(F) lockd(F) sunrpc(F) CPU 0 Pid: 1035, comm: kworker/u:3 Tainted: GF 3.7.0-rc8-fsdevel+ #411 /DG965RY RIP: 0010:[<ffffffffa007db22>] [<ffffffffa007db22>] fscache_put_operation+0x11a/0x2ed [fscache] RSP: 0018:ffff88003e32bcf8 EFLAGS: 00010296 RAX: 000000000000000f RBX: ffff88001818eb78 RCX: ffffffff6c102000 RDX: ffffffff8102d1ad RSI: ffffffff6c102000 RDI: ffffffff8102d1d6 RBP: ffff88003e32bd18 R08: 0000000000000002 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffa00811da R13: 0000000000000001 R14: 0000000100625d26 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88003bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007fff7dd31c68 CR3: 000000003d730000 CR4: 00000000000007f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kworker/u:3 (pid: 1035, threadinfo ffff88003e32a000, task ffff88003bb38080) Stack: ffffffff8102d1ad ffff88001818eb78 ffffffffa00811da 0000000000000001 ffff88003e32bd48 ffffffffa007f0ad ffff88001818eb78 ffffffff819583c0 ffff88003df24e00 ffff88003882c3e0 ffff88003e32bde8 ffffffff81042de0 Call Trace: [<ffffffff8102d1ad>] ? vprintk_emit+0x3c6/0x41a [<ffffffffa00811da>] ? __fscache_read_or_alloc_pages+0x4bc/0x4bc [fscache] [<ffffffffa007f0ad>] fscache_op_work_func+0xec/0x123 [fscache] [<ffffffff81042de0>] process_one_work+0x21c/0x3b0 [<ffffffff81042d82>] ? process_one_work+0x1be/0x3b0 [<ffffffffa007efc1>] ? fscache_operation_gc+0x23e/0x23e [fscache] [<ffffffff8104332e>] worker_thread+0x202/0x2df [<ffffffff8104312c>] ? rescuer_thread+0x18e/0x18e [<ffffffff81047c1c>] kthread+0xd0/0xd8 [<ffffffff81421bfa>] ? _raw_spin_unlock_irq+0x29/0x3e [<ffffffff81047b4c>] ? __init_kthread_worker+0x55/0x55 [<ffffffff814227ec>] ret_from_fork+0x7c/0xb0 [<ffffffff81047b4c>] ? __init_kthread_worker+0x55/0x55 Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs/fscache')
-rw-r--r--fs/fscache/page.c22
1 files changed, 20 insertions, 2 deletions
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index 5b5d9081c8b..ef0218f5080 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -699,9 +699,27 @@ static void fscache_write_op(struct fscache_operation *_op)
spin_lock(&object->lock);
cookie = object->cookie;
- if (!fscache_object_is_active(object) || !cookie) {
+ if (!fscache_object_is_active(object)) {
+ /* If we get here, then the on-disk cache object likely longer
+ * exists, so we should just cancel this write operation.
+ */
spin_unlock(&object->lock);
- _leave("");
+ op->op.state = FSCACHE_OP_ST_CANCELLED;
+ _leave(" [inactive]");
+ return;
+ }
+
+ if (!cookie) {
+ /* If we get here, then the cookie belonging to the object was
+ * detached, probably by the cookie being withdrawn due to
+ * memory pressure, which means that the pages we might write
+ * to the cache from no longer exist - therefore, we can just
+ * cancel this write operation.
+ */
+ spin_unlock(&object->lock);
+ op->op.state = FSCACHE_OP_ST_CANCELLED;
+ _leave(" [cancel] op{f=%lx s=%u} obj{s=%u f=%lx}",
+ _op->flags, _op->state, object->state, object->flags);
return;
}