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authorNick Piggin <npiggin@suse.de>2008-07-26 06:45:26 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-26 23:00:06 +0400
commitbc40d73c950146725e9e768e856a416ec8949065 (patch)
tree7d12351ddeb6a281ff7a9b5db543067c710d1859 /fs
parentf5dd33c494a427b1d1a3b574de5c9e511c888864 (diff)
downloadlinux-bc40d73c950146725e9e768e856a416ec8949065.tar.xz
splice: use get_user_pages_fast
Use get_user_pages_fast in splice. This reverts some mmap_sem batching there, however the biggest problem with mmap_sem tends to be hold times blocking out other threads rather than cacheline bouncing. Further: on architectures that implement get_user_pages_fast without locks, mmap_sem can be avoided completely anyway. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Andi Kleen <andi@firstfloor.org> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Zach Brown <zach.brown@oracle.com> Cc: Jens Axboe <jens.axboe@oracle.com> Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/splice.c41
1 files changed, 3 insertions, 38 deletions
diff --git a/fs/splice.c b/fs/splice.c
index 399442179d89..47dc1a445d1f 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1161,36 +1161,6 @@ static long do_splice(struct file *in, loff_t __user *off_in,
}
/*
- * Do a copy-from-user while holding the mmap_semaphore for reading, in a
- * manner safe from deadlocking with simultaneous mmap() (grabbing mmap_sem
- * for writing) and page faulting on the user memory pointed to by src.
- * This assumes that we will very rarely hit the partial != 0 path, or this
- * will not be a win.
- */
-static int copy_from_user_mmap_sem(void *dst, const void __user *src, size_t n)
-{
- int partial;
-
- if (!access_ok(VERIFY_READ, src, n))
- return -EFAULT;
-
- pagefault_disable();
- partial = __copy_from_user_inatomic(dst, src, n);
- pagefault_enable();
-
- /*
- * Didn't copy everything, drop the mmap_sem and do a faulting copy
- */
- if (unlikely(partial)) {
- up_read(&current->mm->mmap_sem);
- partial = copy_from_user(dst, src, n);
- down_read(&current->mm->mmap_sem);
- }
-
- return partial;
-}
-
-/*
* Map an iov into an array of pages and offset/length tupples. With the
* partial_page structure, we can map several non-contiguous ranges into
* our ones pages[] map instead of splitting that operation into pieces.
@@ -1203,8 +1173,6 @@ static int get_iovec_page_array(const struct iovec __user *iov,
{
int buffers = 0, error = 0;
- down_read(&current->mm->mmap_sem);
-
while (nr_vecs) {
unsigned long off, npages;
struct iovec entry;
@@ -1213,7 +1181,7 @@ static int get_iovec_page_array(const struct iovec __user *iov,
int i;
error = -EFAULT;
- if (copy_from_user_mmap_sem(&entry, iov, sizeof(entry)))
+ if (copy_from_user(&entry, iov, sizeof(entry)))
break;
base = entry.iov_base;
@@ -1247,9 +1215,8 @@ static int get_iovec_page_array(const struct iovec __user *iov,
if (npages > PIPE_BUFFERS - buffers)
npages = PIPE_BUFFERS - buffers;
- error = get_user_pages(current, current->mm,
- (unsigned long) base, npages, 0, 0,
- &pages[buffers], NULL);
+ error = get_user_pages_fast((unsigned long)base, npages,
+ 0, &pages[buffers]);
if (unlikely(error <= 0))
break;
@@ -1288,8 +1255,6 @@ static int get_iovec_page_array(const struct iovec __user *iov,
iov++;
}
- up_read(&current->mm->mmap_sem);
-
if (buffers)
return buffers;