From 3d7a641e544e428191667e8b1f83f96fa46dbd65 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 19 Nov 2009 18:10:23 +0000 Subject: SLOW_WORK: Wait for outstanding work items belonging to a module to clear Wait for outstanding slow work items belonging to a module to clear when unregistering that module as a user of the facility. This prevents the put_ref code of a work item from being taken away before it returns. Signed-off-by: David Howells --- fs/fscache/operation.c | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/fscache/operation.c') diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c index e7f8d53b8b6b..f1a2857b2ff5 100644 --- a/fs/fscache/operation.c +++ b/fs/fscache/operation.c @@ -453,6 +453,7 @@ static void fscache_op_execute(struct slow_work *work) } const struct slow_work_ops fscache_op_slow_work_ops = { + .owner = THIS_MODULE, .get_ref = fscache_op_get_ref, .put_ref = fscache_op_put_ref, .execute = fscache_op_execute, -- cgit v1.2.2 From 440f0affe247e9990c8f8778f1861da4fd7d5e50 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 19 Nov 2009 18:11:01 +0000 Subject: FS-Cache: Annotate slow-work runqueue proc lines for FS-Cache work items Annotate slow-work runqueue proc lines for FS-Cache work items. Objects include the object ID and the state. Operations include the object ID, the operation ID and the operation type and state. Signed-off-by: David Howells --- fs/fscache/operation.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'fs/fscache/operation.c') diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c index f1a2857b2ff5..91bbe6f0377c 100644 --- a/fs/fscache/operation.c +++ b/fs/fscache/operation.c @@ -13,6 +13,7 @@ #define FSCACHE_DEBUG_LEVEL OPERATION #include +#include #include "internal.h" atomic_t fscache_op_debug_id; @@ -31,6 +32,8 @@ void fscache_enqueue_operation(struct fscache_operation *op) _enter("{OBJ%x OP%x,%u}", op->object->debug_id, op->debug_id, atomic_read(&op->usage)); + fscache_set_op_state(op, "EnQ"); + ASSERT(op->processor != NULL); ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE); ASSERTCMP(atomic_read(&op->usage), >, 0); @@ -67,6 +70,8 @@ EXPORT_SYMBOL(fscache_enqueue_operation); static void fscache_run_op(struct fscache_object *object, struct fscache_operation *op) { + fscache_set_op_state(op, "Run"); + object->n_in_progress++; if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) wake_up_bit(&op->flags, FSCACHE_OP_WAITING); @@ -87,6 +92,8 @@ int fscache_submit_exclusive_op(struct fscache_object *object, _enter("{OBJ%x OP%x},", object->debug_id, op->debug_id); + fscache_set_op_state(op, "SubmitX"); + spin_lock(&object->lock); ASSERTCMP(object->n_ops, >=, object->n_in_progress); ASSERTCMP(object->n_ops, >=, object->n_exclusive); @@ -190,6 +197,8 @@ int fscache_submit_op(struct fscache_object *object, ASSERTCMP(atomic_read(&op->usage), >, 0); + fscache_set_op_state(op, "Submit"); + spin_lock(&object->lock); ASSERTCMP(object->n_ops, >=, object->n_in_progress); ASSERTCMP(object->n_ops, >=, object->n_exclusive); @@ -298,6 +307,8 @@ void fscache_put_operation(struct fscache_operation *op) if (!atomic_dec_and_test(&op->usage)) return; + fscache_set_op_state(op, "Put"); + _debug("PUT OP"); if (test_and_set_bit(FSCACHE_OP_DEAD, &op->flags)) BUG(); @@ -452,9 +463,27 @@ static void fscache_op_execute(struct slow_work *work) _leave(""); } +/* + * describe an operation for slow-work debugging + */ +#ifdef CONFIG_SLOW_WORK_PROC +static void fscache_op_desc(struct slow_work *work, struct seq_file *m) +{ + struct fscache_operation *op = + container_of(work, struct fscache_operation, slow_work); + + seq_printf(m, "FSC: OBJ%x OP%x: %s/%s fl=%lx", + op->object->debug_id, op->debug_id, + op->name, op->state, op->flags); +} +#endif + const struct slow_work_ops fscache_op_slow_work_ops = { .owner = THIS_MODULE, .get_ref = fscache_op_get_ref, .put_ref = fscache_op_put_ref, .execute = fscache_op_execute, +#ifdef CONFIG_SLOW_WORK_PROC + .desc = fscache_op_desc, +#endif }; -- cgit v1.2.2 From 4fbf4291aa15926cd4fdca0ffe9122e89d0459db Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 19 Nov 2009 18:11:04 +0000 Subject: FS-Cache: Allow the current state of all objects to be dumped Allow the current state of all fscache objects to be dumped by doing: cat /proc/fs/fscache/objects By default, all objects and all fields will be shown. This can be restricted by adding a suitable key to one of the caller's keyrings (such as the session keyring): keyctl add user fscache:objlist "" @s The are: K Show hexdump of object key (don't show if not given) A Show hexdump of object aux data (don't show if not given) And paired restrictions: C Show objects that have a cookie c Show objects that don't have a cookie B Show objects that are busy b Show objects that aren't busy W Show objects that have pending writes w Show objects that don't have pending writes R Show objects that have outstanding reads r Show objects that don't have outstanding reads S Show objects that have slow work queued s Show objects that don't have slow work queued If neither side of a restriction pair is given, then both are implied. For example: keyctl add user fscache:objlist KB @s shows objects that are busy, and lists their object keys, but does not dump their auxiliary data. It also implies "CcWwRrSs", but as 'B' is given, 'b' is not implied. Signed-off-by: David Howells --- fs/fscache/operation.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'fs/fscache/operation.c') diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c index 91bbe6f0377c..09e43b6e822f 100644 --- a/fs/fscache/operation.c +++ b/fs/fscache/operation.c @@ -322,6 +322,9 @@ void fscache_put_operation(struct fscache_operation *op) object = op->object; + if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags)) + atomic_dec(&object->n_reads); + /* now... we may get called with the object spinlock held, so we * complete the cleanup here only if we can immediately acquire the * lock, and defer it otherwise */ -- cgit v1.2.2 From 5753c441889253e4323eee85f791a1d64cf08196 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 19 Nov 2009 18:11:19 +0000 Subject: FS-Cache: Permit cache retrieval ops to be interrupted in the initial wait phase Permit the operations to retrieve data from the cache or to allocate space in the cache for future writes to be interrupted whilst they're waiting for permission for the operation to proceed. Typically this wait occurs whilst the cache object is being looked up on disk in the background. If an interruption occurs, and the operation has not yet been given the go-ahead to run, the operation is dequeued and cancelled, and control returns to the read operation of the netfs routine with none of the requested pages having been read or in any way marked as known by the cache. This means that the initial wait is done interruptibly rather than uninterruptibly. In addition, extra stats values are made available to show the number of ops cancelled and the number of cache space allocations interrupted. Signed-off-by: David Howells --- fs/fscache/operation.c | 82 +++++++++++++++++++++++++++++++++----------------- 1 file changed, 54 insertions(+), 28 deletions(-) (limited to 'fs/fscache/operation.c') diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c index 09e43b6e822f..296492efb81b 100644 --- a/fs/fscache/operation.c +++ b/fs/fscache/operation.c @@ -34,32 +34,31 @@ void fscache_enqueue_operation(struct fscache_operation *op) fscache_set_op_state(op, "EnQ"); + ASSERT(list_empty(&op->pend_link)); ASSERT(op->processor != NULL); ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE); ASSERTCMP(atomic_read(&op->usage), >, 0); - if (list_empty(&op->pend_link)) { - switch (op->flags & FSCACHE_OP_TYPE) { - case FSCACHE_OP_FAST: - _debug("queue fast"); - atomic_inc(&op->usage); - if (!schedule_work(&op->fast_work)) - fscache_put_operation(op); - break; - case FSCACHE_OP_SLOW: - _debug("queue slow"); - slow_work_enqueue(&op->slow_work); - break; - case FSCACHE_OP_MYTHREAD: - _debug("queue for caller's attention"); - break; - default: - printk(KERN_ERR "FS-Cache: Unexpected op type %lx", - op->flags); - BUG(); - break; - } - fscache_stat(&fscache_n_op_enqueue); + fscache_stat(&fscache_n_op_enqueue); + switch (op->flags & FSCACHE_OP_TYPE) { + case FSCACHE_OP_FAST: + _debug("queue fast"); + atomic_inc(&op->usage); + if (!schedule_work(&op->fast_work)) + fscache_put_operation(op); + break; + case FSCACHE_OP_SLOW: + _debug("queue slow"); + slow_work_enqueue(&op->slow_work); + break; + case FSCACHE_OP_MYTHREAD: + _debug("queue for caller's attention"); + break; + default: + printk(KERN_ERR "FS-Cache: Unexpected op type %lx", + op->flags); + BUG(); + break; } } EXPORT_SYMBOL(fscache_enqueue_operation); @@ -97,6 +96,7 @@ int fscache_submit_exclusive_op(struct fscache_object *object, spin_lock(&object->lock); ASSERTCMP(object->n_ops, >=, object->n_in_progress); ASSERTCMP(object->n_ops, >=, object->n_exclusive); + ASSERT(list_empty(&op->pend_link)); ret = -ENOBUFS; if (fscache_object_is_active(object)) { @@ -202,6 +202,7 @@ int fscache_submit_op(struct fscache_object *object, spin_lock(&object->lock); ASSERTCMP(object->n_ops, >=, object->n_in_progress); ASSERTCMP(object->n_ops, >=, object->n_exclusive); + ASSERT(list_empty(&op->pend_link)); ostate = object->state; smp_rmb(); @@ -273,12 +274,7 @@ void fscache_start_operations(struct fscache_object *object) stop = true; } list_del_init(&op->pend_link); - object->n_in_progress++; - - if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) - wake_up_bit(&op->flags, FSCACHE_OP_WAITING); - if (op->processor) - fscache_enqueue_operation(op); + fscache_run_op(object, op); /* the pending queue was holding a ref on the object */ fscache_put_operation(op); @@ -290,6 +286,36 @@ void fscache_start_operations(struct fscache_object *object) object->n_in_progress, object->debug_id); } +/* + * cancel an operation that's pending on an object + */ +int fscache_cancel_op(struct fscache_operation *op) +{ + struct fscache_object *object = op->object; + int ret; + + _enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id); + + spin_lock(&object->lock); + + ret = -EBUSY; + if (!list_empty(&op->pend_link)) { + fscache_stat(&fscache_n_op_cancelled); + list_del_init(&op->pend_link); + object->n_ops--; + if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) + object->n_exclusive--; + if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) + wake_up_bit(&op->flags, FSCACHE_OP_WAITING); + fscache_put_operation(op); + ret = 0; + } + + spin_unlock(&object->lock); + _leave(" = %d", ret); + return ret; +} + /* * release an operation * - queues pending ops if this is the last in-progress op -- cgit v1.2.2 From e3d4d28b1c8cc7c26536a50b43d86ccd39878550 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 19 Nov 2009 18:11:32 +0000 Subject: 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: [] fscache_submit_op+0x3ff/0x45a [fscache] [] __fscache_read_or_alloc_pages+0x187/0x3c4 [fscache] [] ? nfs_readpage_from_fscache_complete+0x0/0x66 [nfs] [] __nfs_readpages_from_fscache+0x7e/0x176 [nfs] [] ? __alloc_pages_nodemask+0x11c/0x5cf [] nfs_readpages+0x114/0x1d7 [nfs] [] __do_page_cache_readahead+0x15f/0x1ec [] ? __do_page_cache_readahead+0x73/0x1ec [] ra_submit+0x1c/0x20 [] ondemand_readahead+0x227/0x23a [] page_cache_sync_readahead+0x17/0x19 [] generic_file_aio_read+0x236/0x5a0 [] nfs_file_read+0xe4/0xf3 [nfs] [] do_sync_read+0xe3/0x120 [] ? _spin_unlock_irq+0x2b/0x31 [] ? autoremove_wake_function+0x0/0x34 [] ? selinux_file_permission+0x5d/0x10f [] ? thread_return+0x3e/0x101 [] ? security_file_permission+0x11/0x13 [] vfs_read+0xaa/0x16f [] ? trace_hardirqs_on_caller+0x10c/0x130 [] sys_read+0x45/0x6c [] 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 --- fs/fscache/operation.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'fs/fscache/operation.c') diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c index 296492efb81b..313e79a14266 100644 --- a/fs/fscache/operation.c +++ b/fs/fscache/operation.c @@ -232,6 +232,11 @@ int fscache_submit_op(struct fscache_object *object, list_add_tail(&op->pend_link, &object->pending_ops); fscache_stat(&fscache_n_op_pend); ret = 0; + } else if (object->state == FSCACHE_OBJECT_DYING || + object->state == FSCACHE_OBJECT_LC_DYING || + object->state == FSCACHE_OBJECT_WITHDRAWING) { + fscache_stat(&fscache_n_op_rejected); + ret = -ENOBUFS; } else if (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) { fscache_report_unexpected_submission(object, op, ostate); ASSERT(!fscache_object_is_active(object)); -- cgit v1.2.2