Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=674b892ede247ef4fb8d00918f02e29c32b9bbaf
Commit: 674b892ede247ef4fb8d00918f02e29c32b9bbaf
Parent: 8268f5a7415d914fc855a86aa2284ac819dc6b2e
Author: Nick Piggin <[EMAIL PROTECTED]>
AuthorDate: Tue Oct 16 01:25:03 2007 -0700
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue Oct 16 09:42:55 2007 -0700
mm: restore KERNEL_DS optimisations
Restore the KERNEL_DS optimisation, especially helpful to the 2copy write
path.
This may be a pretty questionable gain in most cases, especially after the
legacy 2copy write path is removed, but it doesn't cost much.
Signed-off-by: Nick Piggin <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
mm/filemap.c | 11 +++++++++--
1 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index ec25ba1..ca04226 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2061,7 +2061,7 @@ static ssize_t generic_perform_write_2copy(struct file
*file,
* cannot take a pagefault with the destination page locked.
* So pin the source page to copy it.
*/
- if (!PageUptodate(page)) {
+ if (!PageUptodate(page) && !segment_eq(get_fs(), KERNEL_DS)) {
unlock_page(page);
src_page = alloc_page(GFP_KERNEL);
@@ -2186,6 +2186,13 @@ static ssize_t generic_perform_write(struct file *file,
const struct address_space_operations *a_ops = mapping->a_ops;
long status = 0;
ssize_t written = 0;
+ unsigned int flags = 0;
+
+ /*
+ * Copies from kernel address space cannot fail (NFSD is a big user).
+ */
+ if (segment_eq(get_fs(), KERNEL_DS))
+ flags |= AOP_FLAG_UNINTERRUPTIBLE;
do {
struct page *page;
@@ -2217,7 +2224,7 @@ again:
break;
}
- status = a_ops->write_begin(file, mapping, pos, bytes, 0,
+ status = a_ops->write_begin(file, mapping, pos, bytes, flags,
&page, &fsdata);
if (unlikely(status))
break;
-
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