This lock was used for two different purposes in two places. The use
in cache_read() is redundant because cd->queue_lock is also taken
and can be removed without harm. The use in cache_write() protects a
global buffer which can be eliminated and replaced with a temporarily
allocated page; this also removes an unnecessary global bottleneck
when multiple rpc.mountd threads are writing down into the kernel.
Signed-off-by: Greg Banks <gnb@xxxxxxx>
---
net/sunrpc/cache.c | 34 +++++++++++++++-------------------
1 file changed, 15 insertions(+), 19 deletions(-)
Index: bfields/net/sunrpc/cache.c
===================================================================
--- bfields.orig/net/sunrpc/cache.c
+++ bfields/net/sunrpc/cache.c
@@ -674,8 +674,6 @@ void cache_clean_deferred(void *owner)
*
*/
-static DEFINE_MUTEX(queue_io_mutex);
-
struct cache_queue {
struct list_head list;
int reader; /* if 0, then request */
@@ -703,8 +701,6 @@ cache_read(struct file *filp, char __use
if (count == 0)
return 0;
- mutex_lock(&queue_io_mutex); /* protect against multiple concurrent
- * readers on this file */
again:
spin_lock(&cd->queue_lock);
/* need to find next request */
@@ -716,7 +712,6 @@ cache_read(struct file *filp, char __use
}
if (rp->q.list.next == &cd->queue) {
spin_unlock(&cd->queue_lock);
- mutex_unlock(&queue_io_mutex);
BUG_ON(rp->offset);
return 0;
}
@@ -763,37 +758,38 @@ cache_read(struct file *filp, char __use
}
if (err == -EAGAIN)
goto again;
- mutex_unlock(&queue_io_mutex);
return err ? err : count;
}
-static char write_buf[8192]; /* protected by queue_io_mutex */
-
static ssize_t
cache_write(struct file *filp, const char __user *buf, size_t count,
loff_t *ppos)
{
int err;
struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;
+ char *tmp;
+ int tmp_size = PAGE_SIZE;
if (count == 0)
return 0;
- if (count >= sizeof(write_buf))
+ if (count >= tmp_size)
return -EINVAL;
- mutex_lock(&queue_io_mutex);
+ tmp = kmalloc(tmp_size, GFP_KERNEL);
+ if (!tmp)
+ return -ENOMEM;
- if (copy_from_user(write_buf, buf, count)) {
- mutex_unlock(&queue_io_mutex);
- return -EFAULT;
- }
- write_buf[count] = '\0';
+ err = -EFAULT;
+ if (copy_from_user(tmp, buf, count))
+ goto out;
+
+ tmp[count] = '\0';
+ err = -EINVAL;
if (cd->cache_parse)
- err = cd->cache_parse(cd, write_buf, count);
- else
- err = -EINVAL;
+ err = cd->cache_parse(cd, tmp, count);
- mutex_unlock(&queue_io_mutex);
+out:
+ kfree(tmp);
return err ? err : count;
}
--
--
Greg Banks, P.Engineer, SGI Australian Software Group.
the brightly coloured sporks of revolution.
I don't speak for SGI.
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