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/page.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 48 insertions(+), 7 deletions(-) (limited to 'fs/fscache/page.c') diff --git a/fs/fscache/page.c b/fs/fscache/page.c index 250dfd34c07b..e6f2e61133a1 100644 --- a/fs/fscache/page.c +++ b/fs/fscache/page.c @@ -295,8 +295,20 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie, if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) { _debug(">>> WT"); fscache_stat(&fscache_n_retrieval_op_waits); - wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, - fscache_wait_bit, TASK_UNINTERRUPTIBLE); + if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, + fscache_wait_bit_interruptible, + TASK_INTERRUPTIBLE) < 0) { + ret = fscache_cancel_op(&op->op); + if (ret == 0) { + ret = -ERESTARTSYS; + goto error; + } + + /* it's been removed from the pending queue by another + * party, so we should get to run shortly */ + wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, + fscache_wait_bit, TASK_UNINTERRUPTIBLE); + } _debug("<<< GO"); } @@ -313,6 +325,7 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie, fscache_stat_d(&fscache_n_cop_read_or_alloc_page); } +error: if (ret == -ENOMEM) fscache_stat(&fscache_n_retrievals_nomem); else if (ret == -ERESTARTSYS) @@ -412,8 +425,20 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) { _debug(">>> WT"); fscache_stat(&fscache_n_retrieval_op_waits); - wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, - fscache_wait_bit, TASK_UNINTERRUPTIBLE); + if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, + fscache_wait_bit_interruptible, + TASK_INTERRUPTIBLE) < 0) { + ret = fscache_cancel_op(&op->op); + if (ret == 0) { + ret = -ERESTARTSYS; + goto error; + } + + /* it's been removed from the pending queue by another + * party, so we should get to run shortly */ + wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, + fscache_wait_bit, TASK_UNINTERRUPTIBLE); + } _debug("<<< GO"); } @@ -430,6 +455,7 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, fscache_stat_d(&fscache_n_cop_read_or_alloc_pages); } +error: if (ret == -ENOMEM) fscache_stat(&fscache_n_retrievals_nomem); else if (ret == -ERESTARTSYS) @@ -505,8 +531,20 @@ int __fscache_alloc_page(struct fscache_cookie *cookie, if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) { _debug(">>> WT"); fscache_stat(&fscache_n_alloc_op_waits); - wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, - fscache_wait_bit, TASK_UNINTERRUPTIBLE); + if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, + fscache_wait_bit_interruptible, + TASK_INTERRUPTIBLE) < 0) { + ret = fscache_cancel_op(&op->op); + if (ret == 0) { + ret = -ERESTARTSYS; + goto error; + } + + /* it's been removed from the pending queue by another + * party, so we should get to run shortly */ + wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, + fscache_wait_bit, TASK_UNINTERRUPTIBLE); + } _debug("<<< GO"); } @@ -515,7 +553,10 @@ int __fscache_alloc_page(struct fscache_cookie *cookie, ret = object->cache->ops->allocate_page(op, page, gfp); fscache_stat_d(&fscache_n_cop_allocate_page); - if (ret < 0) +error: + if (ret == -ERESTARTSYS) + fscache_stat(&fscache_n_allocs_intr); + else if (ret < 0) fscache_stat(&fscache_n_allocs_nobufs); else fscache_stat(&fscache_n_allocs_ok); -- cgit v1.2.3