From 91c7fbbf63f33c77d8d28de624834a21888842bb Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 14 Dec 2012 11:02:22 +0000 Subject: [PATCH] FS-Cache: Clear remaining page count on retrieval cancellation Provide fscache_cancel_op() with a pointer to a function it should invoke under lock if it cancels an operation. Use this to clear the remaining page count upon cancellation of a pending retrieval operation so that fscache_release_retrieval_op() doesn't get an assertion failure (see below). This can happen when a signal occurs, say from CTRL-C being pressed during data retrieval. FS-Cache: Assertion failed 3 == 0 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/page.c:237! invalid opcode: 0000 [#641] 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: 6075, comm: slurp-q Tainted: GF D 3.7.0-rc8-fsdevel+ #411 /DG965RY RIP: 0010:[] [] fscache_release_retrieval_op+0x75/0xff [fscache] RSP: 0000:ffff88001c6d7988 EFLAGS: 00010296 RAX: 000000000000000f RBX: ffff880014cdfe00 RCX: ffffffff6c102000 RDX: ffffffff8102d1ad RSI: ffffffff6c102000 RDI: ffffffff8102d1d6 RBP: ffff88001c6d7998 R08: 0000000000000002 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 00000000fffffe00 R13: ffff88001c6d7ab4 R14: ffff88001a8638a0 R15: ffff88001552b190 FS: 00007f877aaf0700(0000) GS:ffff88003bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007fff11378fd2 CR3: 000000001c6c6000 CR4: 00000000000007f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process slurp-q (pid: 6075, threadinfo ffff88001c6d6000, task ffff88001c6c4080) Stack: ffffffffa007ec07 ffff880014cdfe00 ffff88001c6d79c8 ffffffffa007db4d ffffffffa007ec07 ffff880014cdfe00 00000000fffffe00 ffff88001c6d7ab4 ffff88001c6d7a38 ffffffffa008116d 0000000000000000 ffff88001c6c4080 Call Trace: [] ? fscache_cancel_op+0x194/0x1cf [fscache] [] fscache_put_operation+0x135/0x2ed [fscache] [] ? fscache_cancel_op+0x194/0x1cf [fscache] [] __fscache_read_or_alloc_pages+0x413/0x4bc [fscache] [] ? __alloc_pages_nodemask+0x195/0x75c [] __nfs_readpages_from_fscache+0x86/0x13d [nfs] [] nfs_readpages+0x186/0x1bd [nfs] [] ? alloc_pages_current+0xc7/0xe4 [] ? __page_cache_alloc+0x84/0x91 [] ? __do_page_cache_readahead+0xa6/0x2e0 [] __do_page_cache_readahead+0x237/0x2e0 [] ? __do_page_cache_readahead+0xa6/0x2e0 [] ra_submit+0x1c/0x20 [] ondemand_readahead+0x359/0x382 [] page_cache_sync_readahead+0x38/0x3a [] generic_file_aio_read+0x26b/0x637 [] ? nfs_mark_delegation_referenced+0xb/0xb [nfsv4] [] nfs_file_read+0xaa/0xcf [nfs] [] do_sync_read+0x91/0xd1 [] vfs_read+0x9b/0x144 [] sys_read+0x44/0x75 [] system_call_fastpath+0x16/0x1b Signed-off-by: David Howells --- fs/fscache/internal.h | 3 ++- fs/fscache/operation.c | 5 ++++- fs/fscache/page.c | 17 ++++++++++++++--- 3 files changed, 20 insertions(+), 5 deletions(-) diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h index 88a48ccb7d9..ee38fef4be5 100644 --- a/fs/fscache/internal.h +++ b/fs/fscache/internal.h @@ -121,7 +121,8 @@ extern int fscache_submit_exclusive_op(struct fscache_object *, struct fscache_operation *); extern int fscache_submit_op(struct fscache_object *, struct fscache_operation *); -extern int fscache_cancel_op(struct fscache_operation *); +extern int fscache_cancel_op(struct fscache_operation *, + void (*)(struct fscache_operation *)); extern void fscache_cancel_all_ops(struct fscache_object *); extern void fscache_abort_object(struct fscache_object *); extern void fscache_start_operations(struct fscache_object *); diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c index 36c59604130..762a9ec4ffa 100644 --- a/fs/fscache/operation.c +++ b/fs/fscache/operation.c @@ -298,7 +298,8 @@ void fscache_start_operations(struct fscache_object *object) /* * cancel an operation that's pending on an object */ -int fscache_cancel_op(struct fscache_operation *op) +int fscache_cancel_op(struct fscache_operation *op, + void (*do_cancel)(struct fscache_operation *)) { struct fscache_object *object = op->object; int ret; @@ -316,6 +317,8 @@ int fscache_cancel_op(struct fscache_operation *op) ASSERT(!list_empty(&op->pend_link)); fscache_stat(&fscache_n_op_cancelled); list_del_init(&op->pend_link); + if (do_cancel) + do_cancel(op); op->state = FSCACHE_OP_ST_CANCELLED; if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) object->n_exclusive--; diff --git a/fs/fscache/page.c b/fs/fscache/page.c index 8a92b9fabe8..ff000e52072 100644 --- a/fs/fscache/page.c +++ b/fs/fscache/page.c @@ -302,6 +302,17 @@ static int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie) return 0; } +/* + * Handle cancellation of a pending retrieval op + */ +static void fscache_do_cancel_retrieval(struct fscache_operation *_op) +{ + struct fscache_retrieval *op = + container_of(_op, struct fscache_retrieval, op); + + op->n_pages = 0; +} + /* * wait for an object to become active (or dead) */ @@ -320,7 +331,7 @@ static int fscache_wait_for_retrieval_activation(struct fscache_object *object, if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, fscache_wait_bit_interruptible, TASK_INTERRUPTIBLE) != 0) { - ret = fscache_cancel_op(&op->op); + ret = fscache_cancel_op(&op->op, fscache_do_cancel_retrieval); if (ret == 0) return -ERESTARTSYS; @@ -338,8 +349,8 @@ check_if_dead: return -ENOBUFS; } if (unlikely(fscache_object_is_dead(object))) { - pr_err("%s() = -ENOBUFS [obj dead %d]", __func__, op->op.state); - fscache_cancel_op(&op->op); + pr_err("%s() = -ENOBUFS [obj dead %d]\n", __func__, op->op.state); + fscache_cancel_op(&op->op, fscache_do_cancel_retrieval); fscache_stat(stat_object_dead); return -ENOBUFS; }