From d94af6dea9cd680fb795dbc409a7360f1c63dc34 Mon Sep 17 00:00:00 2001 From: Stanislav Kinsbursky Date: Mon, 4 Feb 2013 14:03:03 +0300 Subject: [PATCH] SUNRPC: move cache_detail->cache_request callback call to cache_read() The reason to move cache_request() callback call from sunrpc_cache_pipe_upcall() to cache_read() is that this garantees, that cache access will be done userspace process context (only userspace process have proper root context). This is required for NFSd support in container: svc_export_request() (which is cache_request callback) calls d_path(), which, in turn, traverse dentry up to current->fs->root. Kernel threads always have global root, while container have be in "root jail" - i.e. have it's own nested root. Signed-off-by: Stanislav Kinsbursky Signed-off-by: J. Bruce Fields --- net/sunrpc/cache.c | 32 ++++++++++++++++++++------------ 1 file changed, 20 insertions(+), 12 deletions(-) diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index 8ffec5aebeff..55024714f001 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -750,6 +750,18 @@ struct cache_reader { int offset; /* if non-0, we have a refcnt on next request */ }; +static int cache_request(struct cache_detail *detail, + struct cache_request *crq) +{ + char *bp = crq->buf; + int len = PAGE_SIZE; + + detail->cache_request(detail, crq->item, &bp, &len); + if (len < 0) + return -EAGAIN; + return PAGE_SIZE - len; +} + static ssize_t cache_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos, struct cache_detail *cd) { @@ -784,6 +796,13 @@ static ssize_t cache_read(struct file *filp, char __user *buf, size_t count, rq->readers++; spin_unlock(&queue_lock); + if (rq->len == 0) { + err = cache_request(cd, rq); + if (err < 0) + goto out; + rq->len = err; + } + if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) { err = -EAGAIN; spin_lock(&queue_lock); @@ -1145,8 +1164,6 @@ int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h) char *buf; struct cache_request *crq; - char *bp; - int len; if (!detail->cache_request) return -EINVAL; @@ -1166,19 +1183,10 @@ int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h) return -EAGAIN; } - bp = buf; len = PAGE_SIZE; - - detail->cache_request(detail, h, &bp, &len); - - if (len < 0) { - kfree(buf); - kfree(crq); - return -EAGAIN; - } crq->q.reader = 0; crq->item = cache_get(h); crq->buf = buf; - crq->len = PAGE_SIZE - len; + crq->len = 0; crq->readers = 0; spin_lock(&queue_lock); list_add_tail(&crq->q.list, &detail->queue);