The patch titled
splice: use get_user_pages_fast
has been removed from the -mm tree. Its filename was
splice-use-get_user_pages_fast.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: splice: use get_user_pages_fast
From: Nick Piggin <npiggin@xxxxxxx>
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@xxxxxxx>
Cc: Dave Kleikamp <shaggy@xxxxxxxxxxxxxx>
Cc: Andy Whitcroft <apw@xxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Dave Kleikamp <shaggy@xxxxxxxxxxxxxx>
Cc: Badari Pulavarty <pbadari@xxxxxxxxxx>
Cc: Zach Brown <zach.brown@xxxxxxxxxx>
Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
Reviewed-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/splice.c | 41 +++--------------------------------------
1 file changed, 3 insertions(+), 38 deletions(-)
diff -puN fs/splice.c~splice-use-get_user_pages_fast fs/splice.c
--- a/fs/splice.c~splice-use-get_user_pages_fast
+++ a/fs/splice.c
@@ -1161,36 +1161,6 @@ static long do_splice(struct file *in, l
}
/*
- * 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(¤t->mm->mmap_sem);
- partial = copy_from_user(dst, src, n);
- down_read(¤t->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 st
{
int buffers = 0, error = 0;
- down_read(¤t->mm->mmap_sem);
-
while (nr_vecs) {
unsigned long off, npages;
struct iovec entry;
@@ -1213,7 +1181,7 @@ static int get_iovec_page_array(const st
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 st
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 st
iov++;
}
- up_read(¤t->mm->mmap_sem);
-
if (buffers)
return buffers;
_
Patches currently in -mm which might be from npiggin@xxxxxxx are
origin.patch
linux-next.patch
mmu-notifiers-add-list_del_init_rcu.patch
mmu-notifiers-add-mm_take_all_locks-operation.patch
mmu-notifier-core.patch
powerpc-implement-pte_special.patch
powerpc-implement-pte_special-update.patch
powerpc-lockless-get_user_pages.patch
vmscan-move-isolate_lru_page-to-vmscanc.patch
vmscan-move-isolate_lru_page-to-vmscanc-fix.patch
vmscan-split-lru-lists-into-anon-file-sets-splitlru-bdi_cap_swap_backed.patch
mlock-mlocked-pages-are-unevictable.patch
mlock-mlocked-pages-are-unevictable-fix.patch
mlock-mlocked-pages-are-unevictable-fix-fix.patch
mlock-mlocked-pages-are-unevictable-fix-3.patch
mlock-mlocked-pages-are-unevictable-fix-fix-munlock-page-table-walk-now-requires-mm.patch
mmap-handle-mlocked-pages-during-map-remap-unmap.patch
mmap-handle-mlocked-pages-during-map-remap-unmap-cleanup.patch
fix-double-unlock_page-in-2626-rc5-mm3-kernel-bug-at-mm-filemapc-575.patch
vmstat-mlocked-pages-statistics.patch
vmstat-mlocked-pages-statistics-fix-incorrect-mlocked-field-of-proc-meminfo.patch
reiser4.patch
likeliness-accounting-change-and-cleanup.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
