On 2020-05-22 20:59, John Hubbard wrote:
This code was using get_user_pages*(), in a "Case 1" scenario
(Direct IO), using the categorization from [1]. That means that it's
time to convert the get_user_pages*() + put_page() calls to
pin_user_pages*() + unpin_user_pages() calls.
There is some helpful background in [2]: basically, this is a small
part of fixing a long-standing disconnect between pinning pages, and
file systems' use of those pages.
[1] Documentation/core-api/pin_user_pages.rst
[2] "Explicit pinning of user-space pages":
https://lwn.net/Articles/807108/
Cc: Mike Marshall <hubcap@xxxxxxxxxxxx>
Cc: Martin Brandenburg <martin@xxxxxxxxxxxx>
Cc: devel@xxxxxxxxxxxxxxxxxx
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
---
Hi,
Note that I have only compile-tested this patch, although that does
also include cross-compiling for a few other arches.
An update on the run-time testing: Just now, I got basic orangefs tests
running in xfstests, with this patch applied, and it all looks normal.
thanks,
--
John Hubbard
NVIDIA
Changes since v1 [3]: correct the commit description, so that
it refers to "Case 1" instead of "Case 2".
[3] https://lore.kernel.org/r/20200518060139.2828423-1-jhubbard@xxxxxxxxxx
thanks,
John Hubbard
NVIDIA
fs/orangefs/orangefs-bufmap.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/fs/orangefs/orangefs-bufmap.c b/fs/orangefs/orangefs-bufmap.c
index 2bb916d68576..538e839590ef 100644
--- a/fs/orangefs/orangefs-bufmap.c
+++ b/fs/orangefs/orangefs-bufmap.c
@@ -168,10 +168,7 @@ static DEFINE_SPINLOCK(orangefs_bufmap_lock);
static void
orangefs_bufmap_unmap(struct orangefs_bufmap *bufmap)
{
- int i;
-
- for (i = 0; i < bufmap->page_count; i++)
- put_page(bufmap->page_array[i]);
+ unpin_user_pages(bufmap->page_array, bufmap->page_count);
}
static void
@@ -268,7 +265,7 @@ orangefs_bufmap_map(struct orangefs_bufmap *bufmap,
int offset = 0, ret, i;
/* map the pages */
- ret = get_user_pages_fast((unsigned long)user_desc->ptr,
+ ret = pin_user_pages_fast((unsigned long)user_desc->ptr,
bufmap->page_count, FOLL_WRITE, bufmap->page_array);
if (ret < 0)
@@ -280,7 +277,7 @@ orangefs_bufmap_map(struct orangefs_bufmap *bufmap,
for (i = 0; i < ret; i++) {
SetPageError(bufmap->page_array[i]);
- put_page(bufmap->page_array[i]);
+ unpin_user_page(bufmap->page_array[i]);
}
return -ENOMEM;
}
