From 8d76349d359064859217dc292dc8733e209705af Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 5 Dec 2012 13:34:48 +0000 Subject: FS-Cache: Exclusive op submission can BUG if there's been an I/O error The function to submit an exclusive op (fscache_submit_exclusive_op()) can BUG if there's been an I/O error because it may see the parent cache object in an unexpected state. It should only BUG if there hasn't been an I/O error. In this case the problem was produced by remounting the cache partition to be R/O. The EROFS state was detected and the cache was aborted, but not everything handled the aborting correctly. SysRq : Emergency Remount R/O EXT4-fs (sda6): re-mounted. Opts: (null) Emergency Remount complete CacheFiles: I/O Error: Failed to update xattr with error -30 FS-Cache: Cache cachefiles stopped due to I/O error ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:128! invalid opcode: 0000 [#1] SMP CPU 0 Modules linked in: cachefiles nfs fscache auth_rpcgss nfs_acl lockd sunrpc Pid: 6612, comm: kworker/u:2 Not tainted 3.1.0-rc8-fsdevel+ #1093 /DG965RY RIP: 0010:[] [] fscache_submit_exclusive_op+0x2ad/0x2c2 [fscache] RSP: 0018:ffff880000853d40 EFLAGS: 00010206 RAX: ffff880038ac72a8 RBX: ffff8800181f2260 RCX: ffffffff81f2b2b0 RDX: 0000000000000001 RSI: ffffffff8179a478 RDI: ffff8800181f2280 RBP: ffff880000853d60 R08: 0000000000000002 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: ffff880038ac7268 R13: ffff8800181f2280 R14: ffff88003a359190 R15: 000000010122b162 FS: 0000000000000000(0000) GS:ffff88003bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000034cc4a77f0 CR3: 0000000010e96000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kworker/u:2 (pid: 6612, threadinfo ffff880000852000, task ffff880014c3c040) Stack: ffff8800181f2260 ffff8800181f2310 ffff880038ac7268 ffff8800181f2260 ffff880000853dc0 ffffffffa0072375 ffff880037ecfe00 ffff88003a359198 ffff880000853dc0 0000000000000246 0000000000000000 ffff88000a91d308 Call Trace: [] fscache_object_work_func+0x792/0xe65 [fscache] [] process_one_work+0x1eb/0x37f [] ? process_one_work+0x18d/0x37f [] ? fscache_enqueue_dependents+0xd8/0xd8 [fscache] [] worker_thread+0x15a/0x21a [] ? rescuer_thread+0x188/0x188 [] kthread+0x7f/0x87 [] kernel_thread_helper+0x4/0x10 [] ? finish_task_switch+0x45/0xc0 [] ? retint_restore_args+0xe/0xe [] ? __init_kthread_worker+0x53/0x53 [] ? gs_change+0xb/0xb Signed-off-by: David Howells --- fs/fscache/internal.h | 1 + fs/fscache/object.c | 23 +++++++++++++++++------ fs/fscache/operation.c | 13 ++++++++++--- 3 files changed, 28 insertions(+), 9 deletions(-) (limited to 'fs/fscache') diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h index c81179303930..dcb3e1d5dbf6 100644 --- a/fs/fscache/internal.h +++ b/fs/fscache/internal.h @@ -288,6 +288,7 @@ extern const struct file_operations fscache_stats_fops; static inline void fscache_raise_event(struct fscache_object *object, unsigned event) { + BUG_ON(event >= NR_FSCACHE_OBJECT_EVENTS); if (!test_and_set_bit(event, &object->events) && test_bit(event, &object->event_mask)) fscache_enqueue_object(object); diff --git a/fs/fscache/object.c b/fs/fscache/object.c index 2ef8a082a272..2c512cbac380 100644 --- a/fs/fscache/object.c +++ b/fs/fscache/object.c @@ -103,6 +103,7 @@ static void fscache_object_state_machine(struct fscache_object *object) { enum fscache_object_state new_state; struct fscache_cookie *cookie; + int event; ASSERT(object != NULL); @@ -275,7 +276,8 @@ static void fscache_object_state_machine(struct fscache_object *object) /* determine the transition from a lookup state */ lookup_transit: - switch (fls(object->events & object->event_mask) - 1) { + event = fls(object->events & object->event_mask) - 1; + switch (event) { case FSCACHE_OBJECT_EV_WITHDRAW: case FSCACHE_OBJECT_EV_RETIRE: case FSCACHE_OBJECT_EV_RELEASE: @@ -292,7 +294,8 @@ lookup_transit: /* determine the transition from an active state */ active_transit: - switch (fls(object->events & object->event_mask) - 1) { + event = fls(object->events & object->event_mask) - 1; + switch (event) { case FSCACHE_OBJECT_EV_WITHDRAW: case FSCACHE_OBJECT_EV_RETIRE: case FSCACHE_OBJECT_EV_RELEASE: @@ -314,7 +317,8 @@ active_transit: /* determine the transition from a terminal state */ terminal_transit: - switch (fls(object->events & object->event_mask) - 1) { + event = fls(object->events & object->event_mask) - 1; + switch (event) { case FSCACHE_OBJECT_EV_WITHDRAW: new_state = FSCACHE_OBJECT_WITHDRAWING; goto change_state; @@ -347,8 +351,8 @@ done: unsupported_event: printk(KERN_ERR "FS-Cache:" - " Unsupported event %lx [mask %lx] in state %s\n", - object->events, object->event_mask, + " Unsupported event %d [%lx/%lx] in state %s\n", + event, object->events, object->event_mask, fscache_object_states[object->state]); BUG(); } @@ -945,7 +949,7 @@ static void fscache_invalidate_object(struct fscache_object *object) spin_lock(&cookie->lock); if (fscache_submit_exclusive_op(object, op) < 0) - BUG(); + goto submit_op_failed; spin_unlock(&cookie->lock); fscache_put_operation(op); @@ -960,4 +964,11 @@ static void fscache_invalidate_object(struct fscache_object *object) */ fscache_invalidation_complete(cookie); _leave(""); + return; + +submit_op_failed: + spin_unlock(&cookie->lock); + kfree(op); + fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR); + _leave(" [EIO]"); } diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c index c58dbe613266..9e6b7d232bb1 100644 --- a/fs/fscache/operation.c +++ b/fs/fscache/operation.c @@ -84,6 +84,8 @@ static void fscache_run_op(struct fscache_object *object, int fscache_submit_exclusive_op(struct fscache_object *object, struct fscache_operation *op) { + int ret; + _enter("{OBJ%x OP%x},", object->debug_id, op->debug_id); ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED); @@ -116,6 +118,7 @@ int fscache_submit_exclusive_op(struct fscache_object *object, /* need to issue a new write op after this */ clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); + ret = 0; } else if (object->state == FSCACHE_OBJECT_CREATING) { op->object = object; object->n_ops++; @@ -123,13 +126,17 @@ int fscache_submit_exclusive_op(struct fscache_object *object, atomic_inc(&op->usage); list_add_tail(&op->pend_link, &object->pending_ops); fscache_stat(&fscache_n_op_pend); + ret = 0; } else { - /* not allowed to submit ops in any other state */ - BUG(); + /* If we're in any other state, there must have been an I/O + * error of some nature. + */ + ASSERT(test_bit(FSCACHE_IOERROR, &object->cache->flags)); + ret = -EIO; } spin_unlock(&object->lock); - return 0; + return ret; } /* -- cgit v1.2.3-59-g8ed1b